Research and Comparison on Modification of Medical Polylactic Acid

Short Communication

PLA which is widely used in orthopedic implants, drug carriers, and medical films, can be degraded into harmless lactic acid. There are two main methods for the synthesis of PLA: direct polycondensation of lactic acid and ring-opening polymerization of lactide [1]. When lactic acid is directly polycondensed, high molecular weight PLA cannot be obtained due to the production of water. High molecular weight PLA is usually prepared by the ringopening polymerization process of lactide. There are two main ways of PLA in vivo: hydrolysis and enzymatic degradation [2]. In the actual process, the two degradation modes work together, and which mode is dominant is closely related to the internal structure of the material, hydrophilicity, and molecular weight.

PLA Synthesis Method

There are three ways to synthesize PLA, direct polycondensation of lactic acid monomer, ring-opening polymerization of propylene glycol ester and further polymerization of lactic acid prepolymer. The first method is to directly obtain the polymer by the bulk condensation polymerization of lactic acid monomer. This method is simple to operate, low in cost and high in purity, but it is not easy to obtain high molecular weight PLA. The second method which most literatures use to prepare PLA [3], can obtain high molecular weight PLA. Depending on the catalyst, it can usually be divided into anionic ring-opening polymerization, cationic ring-opening polymerization and coordination. Ring-opening polymerization. The third method is to first heat the lactic acid monomer to prepare a prepolymer, then add a catalyst to the system and remove the water generated by the reaction.

Toughening and Modification of PLA

Block Toughening

Block copolymers are generally soft and hard segments connected polymers with good toughness and elasticity. The introduction of polymer segments with low glass transition temperature into the main chain of PLA has obvious toughening effect. Polytrimethylene carbonate and polycaprolactone have good biological activity, can be degraded non-toxic in vivo. At the same time, the monomer can be directly ring-opening polymerization with lactide, which is a biodegradable product. Excellent choice for polymer materials.

Graft Toughening

Graft toughening is generally based on rubber as the main chain, PLA segment as the side chain or direct synthesis of branched PLA. Inside the polymer, the PLA side chains are entangled with each other, which increases the stress transfer and realizes the toughening of the material. The PLA grafting reaction can initiate the polymerization of lactide through macroinitiators to form dendritic polymers to increase the toughness of PLA [4], such as polyisoprene.

Co-Blended Toughening

Co-blended is a method in which two or more polymers are uniformly mixed in a certain way (solution, melt or mixing) to improve material properties. Compared with the copolymerization method, the Co-blended method is simple, low in cost and widely used in industry. Polycaprolactone degradation products are nontoxic, have good biocompatibility, and have high elongation at break, making it the best choice for the toughening phase of biomedical PLA [5].

Plasticizing and Toughening

Plasticizers have good compatibility and can reduce the glass transition temperature of materials, improve the flexibility of glassy polymers, and play a role in toughening and plasticizing [6]. Polyethylene glycol has good biocompatibility, is degradable in vivo and the degradation products are non-toxic. Adding it to PLA can improve the crystallization speed of PLA.

Composite Toughening

In order to improve the mechanical properties of PLA and obtain strong PLA, inorganic nanoparticles can be introduced into the system to form a ternary composite toughened system. Montmorillonite, tricalcium phosphate and hydroxyapatite have been used [7]. It is proved that it can promote the mechanical properties of the material.

Comparison of Different Toughening Methods

The Co-blended toughening is simpler than block toughening and graft toughening, and is easier to use in industry, but it does not significantly improve the thermomechanical properties of PLA. The block toughening has obvious toughening effect on the material, and due to the chemical bonding between the molecular chains, the thermomechanical properties of the polymer change significantly. The above toughening methods are often accompanied by a decrease in mechanical strength. The introduction of nanoparticles can alleviate this situation, but some nanoparticles have poor dispersion, which has a negative impact on the mechanical properties of the material. The above-mentioned toughening methods have advantages and disadvantages and can be selected according to the application requirements. Biomedical materials have high requirements on the controllability of their components, structures, and properties. To achieve the controllable construction of biomedical PLA systems, it is necessary to select appropriate methods for different application scenarios.

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Qubits- Towards a Better Understanding of the Microzymas

Short Communication

Large molecules are far too complex for modern computers to calculate what happens to them during a reaction, but the power of quantum computers could open the doors to further understanding these molecules” [1]. Computing and the computer was hardly in existence or at best in in its infancy (if not in an embryonic stage) when Professor Pierre Antoine Bechamp (died 1908) discovered the microzymas in the 1850s. Whoever will make the next breakthrough in our understanding of the microzymas/cellular dust will have to do a lot of work with computers. Quantum computers to be precise [2-3]. What we have to understand is how and why microzymas coordinate, decoordinate and morph. The similarities between qubits and cellular dust is uncanny as a model thereby [4-5].

Consider the following for this model

1. Let a cell represent a bit and a microzyme a qubit.

2. Microzymas morph into germs.

3. Let zero [0] represent the microzymas and the numeral one [1] represent a germ.

4. Qubit behavior of superposition vis a vis the conventional binary mode of bits mirrors the morphing/pleomorphism of cellular dust to germs and vice versa.

5. Understanding the transitory “flux” state of fluctuation and flexibility during morphing could be realized via quantum computing modelling. In short what microzymas do is a sort of biological quantum entanglement.

6. Also to be utilized are Ramanujan’s summation and string theory.

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The Role of Bentonite Clays in Aflatoxin- Decontamination, Assimilation and Metabolism in Commercial Poultry

Introduction

Defined as secondary toxic fungal metabolites, mycotoxins are the greatest feed safety concerns in tropical regions [1]. They are also the most potent natural carcinogens linked to severe illnesses and an increase in the risk of liver cancer in humans as well as performance decline in commercial poultry [2]. Nonetheless, several agricultural products used for poultry feed formulation are highly susceptible to mycotoxin contamination under humid conditions. As a result, these toxins are more prevalent in tropical areas where humid environmental conditions favor fungal growth and mycotoxin production [2]. For that reason, many countries and multilateral agencies have established regulations to protect humans and poultry from consuming such contaminated products [3]. On the contrary, many underdeveloped countries like Uganda have no regulations on poultry feed safety, leaving farmers with the burden of battling the mycotoxin-associated production constraints.

Among the numerous mycotoxins, aflatoxins (AF) are the most predominant toxins hence largely contributing to the pool of toxins in the poultry feeds [4,5]. These toxins are produced by Aspergillus flavus and Aspergillus parasiticus which are common contaminants in cereal grains, oilseeds, nuts, and animal-based feed formulation ingredients [6,5]. Since these are the key feed formulation ingredients, the risks of aflatoxin toxicity are high in intensive poultry production systems. However, defined as clinical defects associated with aflatoxin ingestion, aflatoxicosis is associated with increased susceptibility to microbial stress, reduction in immune function, feed utilization, egg-laying percentage, and organ health in poultry [6,7]. Since most of the poultry feeds in Uganda are heavily contaminated with aflatoxins [8], a grave threat to commercial poultry production resulting from reduced vaccine efficacy, organ health, and feed conversion efficiency is inevitable [6,9].

On the other hand, there is no practically effective means of decontaminating feeds by destroying aflatoxins without compromising their nutritional quality [9]. This implies that the utilization of chemically inert aflatoxin sequestering agents like bentonite clays and activated carbon needs to be prioritized. However, the choice of any binder is greatly dependent on its availability and the economic feasibility of its utilization. Among the substances investigated as potential aflatoxin-binding agents, bentonites clays and activated charcoal have proved to be the most promising [10]. However, the cost-effectiveness of activated charcoal has been so variable [11], while different bentonite clays have yielded consistently promising results [6]. Recognized for forming stable complexes with aflatoxins, bentonites clays have strong affinities for aflatoxin sequestration in the gastrointestinal tract (GIT) [12]. Such sequestration is achieved through bentonite clay hydration in which the polar water molecules weaken the interaction between the closely packed bentonite layers for aflatoxin molecule intercalation [13,14]. Consequently, the resultant complex can be eliminated in the fecal materials hence preventing aflatoxin absorption into the bloodstream [15-17]. Therefore, among the several aflatoxin decontaminations approaches, bentonite clay utilization is envisaged to offer the most reliable responses.

Discussion

The Aflatoxicosis Feed Problem

Most of the poultry feeds in Uganda are highly contaminated with aflatoxins (65-1000 ppb) far beyond the acceptable limits of 20 ppb [18]. Due to the dependence on such feeds, commercial poultry in Uganda is highly susceptible to aflatoxicosis, which is reflected in the reduced growth and health performance [9,19]. As a result, severe losses due to poor poultry productive performance and health defects are common due to the consumption of aflatoxin-contaminated feeds [20,21]. On the other hand, commercial aflatoxin decontaminants are not readily accessible which culminates in both technological and logistical challenges. Nonetheless, Phillips et al. and Hesham et al. studied the utilization of dissimilar bentonites in broilers and recommended contradictory inclusion levels of 0.5% and 1.0%, respectively [22,23]. In addition, bentonites are very specific in toxin adsorption, yet they also exhibit great diversities in nature [24,25]. This implies that, any attempts to improve poultry performance through bentonite clay-based aflatoxin-decontamination yield inconsistent results for different bentonite clay deposits. Such inconsistencies are attributed to the highly variable location-specific physiochemical properties among the bentonite’s clays hence the need for location-specific optimum inclusion level determination [25].

Furthermore, comparable studies on other bentonites clays have been conducted, while none has been done particularly on the Albertine bentonite clays. Besides, these studies also do not highlight responses of broiler and layer chickens with respect to aflatoxin carry-over, relative organ health, blood antibody titers alongside egg production indices. In addition, no studies have compared the performance of commercially available aflatoxin binders with the Albertine bentonite clays. Therefore, due to the inconsistent and insufficient information regarding the optimum bentonite clay inclusion levels in poultry feeds coupled with a dearth of information on the Albertine bentonites clays as aflatoxin binders [9], a study to assess the effect of adding these clays and commercial binders as aflatoxin decontaminants was necessary.

The Decontamination Potential of Bentonite Clays

The consumption of aflatoxin-contaminated feeds poses vast aflatoxicosis-related production deficits as well as contamination of poultry products [26]. The resultant aflatoxicosis, which is associated with compromised feed conversion efficiency, reduced vaccine efficacy, and histological organ deterioration, becomes a key production challenge [7,6]. Such challenges not only increase the cost of production but also the risk of losing birds due to highly infectious diseases like Newcastle and infectious bursal disease, which are known to cause up to 100% chicken mortality [26,27]. For that reason, poultry productivity cannot be improved without embracing aflatoxin-decontamination technologies from the feeds. Whereas research has shown that aflatoxin decontamination improves commercial poultry performance [26] the spectrum of decontamination techniques is limited to chemically inert bentonite clay binders and activated carbon. However, the costs involved in the production of activated carbon are prohibitive which results in its scarcity while bentonite clays are readily available as waste in oil extraction [9]. Fortunately, Uganda is endowed with huge deposits of bentonite clays in the Albertine graben region. Elsewhere, these bentonite clays have been reported to have aflatoxin sequestration abilities but with noticeable variations due to physiochemical diversity [28,22,25]. In addition, there is also a scarcity of literature regarding the optimum inclusion levels of the different Albertine bentonite clays as well as their comparative performance with respect to the commercial binders in poultry feeds. Consequently, despite the availability of such bentonite clays, farmers still make huge aflatoxicosis-induced losses due to poor feed utilization, reduced vaccine potency, and hence high mortalities. Therefore, the use of the Albertine bentonite clays as aflatoxin- binders would be a more sustainable decontamination method of averting aflatoxicosis to offset the heavy poultry production losses and the carcinogenic consequences of consuming contaminated poultry products.

Occurrence of Mycotoxins in Foods

Defined as secondary toxic metabolites of Aspergillus species, mycotoxins can be produced on a variety of products from plant and animal origins containing more than 95% water activity [29,30]. The term mycotoxin comes from the Greek word ‘mykes’ meaning mold, and ‘toxicum’ meaning poison that causes a clinical condition referred to as mycotoxicosis [30,31]. Besides, mycotoxins are also reported to be harmful to both humans and animals when absorbed either through ingestion, inhalation, or dermal absorption [4]. However, it was later discovered that ingestion through contaminated foods is the main source of exposure to both humans and livestock [29]. This implies that; besides the direct consumption of contaminated products, humans can also get intoxicated during livestock feed preparation [4]. Recognized for their toxicity, mycotoxins have been reported to be more serious in tropical humid regions where climatic conditions favor the growth of Aspergillus species [32,18]. Such humid conditions, poor postharvest handling, and poor storage facilities make poultry feeds highly susceptible to fungal contamination [32]. Consequently, most poultry feeds in Uganda are found to be highly contaminated with aflatoxins ranging between 65 and 1000 ppb [18]. However, such contamination levels are far beyond the limit of 20 ppb beyond which feeds become unsafe for consumption [33]. Among the many mycotoxins discovered, aflatoxins are the most toxic and highly carcinogenic metabolites of Aspergillus species [4]. Moreover, these toxins which also naturally occur in combination are identified as class one human hepatocellular carcinogens [34]. In addition, aflatoxins B1 can also be metabolized in animal tissues to aflatoxin M1 from bio-activation pathways and excreted in milk [35] hence propagating the effects to infants and higher in the food chain.

Occurrence of Aflatoxins in Livestock Feeds

Aflatoxins were first isolated and characterized from Aspergillus species in poorly stored grains [36]. They were later identified to be associated with the killing of young turkeys in England and ducklings in Kenya as well as Uganda [36,29]. Therefore, these outbreaks gave way to a multitude of discoveries in determining the different types of aflatoxins alongside the associated clinical signs [37]. In addition, these toxins were discovered to be hepatotoxic with their susceptibility being dependent on species, age, nutritional status, and duration of exposure [38]. Currently, aflatoxins are known to be mainly produced by Aspergillus flavus, Aspergillus parasiticus, Aspergillus nomius which use livestock feeds as substrates [39]. Whereas 20 aflatoxins have been identified, only four (B1, B2, G1, and G2) have been widely studied due to their magnitudes of toxicity [40]. Among the four, aflatoxin B1 is the most common and dangerous to both humans and livestock [3]. However, aflatoxins naturally exist in combinations implying that focus has to be put on their synergistic effects rather than the individual effects [41]. Aflatoxins B1, B2, G1, and G2 are widely studied due to their high prevalence in food products and toxic effects [42,30]. Identified to be metabolites of aflatoxin B1 and B2, respectively, aflatoxins M1 and M2 occur in both milk and eggs of species fed aflatoxincontaminated diets [41] Besides the active aflatoxins, significant quantities of conjugated aflatoxins have also been reported to exist in feeds as well [43]. Such conjugated aflatoxins can cause unexpected toxicity when they are hydrolyzed to the precursor toxins in the gastrointestinal tract (GIT) [43]. Furthermore, as part of plant metabolism, some aflatoxins can be transformed into conjugated forms presenting additional forms of toxicity [44]. For instance, zearalenone-4-beta-d- glucopyranoside, zearalenone and deoxynivalenol glucosides which are precursors can be metabolized to the respective active toxins in the GIT [45,46]. Unfortunately, these precursors cannot be detected during routine analysis, yet they can hydrolyze during digestion contributing to the toxin pool in the GIT [45].

Perseverance of Aflatoxicosis

More than ten thousand million metric tons of grains are lost annually due to aflatoxin contamination [47]. In addition, more than four billion individuals in developing countries get chronically exposed to aflatoxicosis every year due to contaminated food consumption [48]. Such chronic exposure is largely attributed to heavy dependence on subsistence farming, unregulated local markets, and the lack of policy regulations on food and feed safety [49]. Consequently, the large aflatoxicosis outbreaks like those in Kenya and Togo claimed many lives [41] while survivors suffered from jaundice, leg edema, and hepatomegaly as well as malnutrition- related symptoms [50,51]. In fact, these outbreaks are traced to be originating from homegrown maize by subsistence farmers who have poor storage facilities [41] Typically, in this crisis 55% of maize products had contamination levels greater than 20 ppb, 35% had levels exceeding 100 ppb, and 7% beyond 1000 ppb [41]. Similarly, related cases were reported in India and China [52] which cases were all established after detecting the clinical signs of acute aflatoxicosis [48].

Effects of Aflatoxins on Human Health

Recognized as a risk factor for cancer [4], aflatoxicosis is characterized by adverse immunological and nutritional effects [48]. Among the aflatoxins, AFB1 and mixtures of AFG1, and AFM1 have been reported to be the major causes of chronic aflatoxicosis and human carcinogens [34]. Besides the carcinogenic effects, ingestion of foods contaminated with relatively lower aflatoxin levels over a long period has been reported to cause jaundice, liver cancer, chronic hepatitis [53], infertility, and impaired nutrient utilization in infants [54]. On the other hand, the ingestion of highly contaminated feeds results in acute hepatic failure, hemorrhages, digestion alterations, mental changes, and coma [48]. Besides direct chronic aflatoxicosis, aflatoxins have also been reported to complement hepatitis B in the causation of liver cancer [55]. Ultimately, the lack of policy regulations in developing countries of Southeast Asia and sub-Saharan Africa accounts for the high incidences of aflatoxicosis [41]. Such incidences, therefore, account for the fact that hepatocellular carcinoma is the fifth leading cause of cancer mortality in the world [56]. Therefore, this fact justifies the correlation between the high levels of aflatoxins contamination in maize with a high incidence of human hepatocellular carcinomas.

Biochemical Properties and Aflatoxin Metabolism

Given suitable conditions of 80-85% relative humidity and temperature of 28-35˚C up to 20 types of aflatoxins can be produced on a variety of feed substrates. However, among these naturally occurring toxins, aflatoxin B1, B2, G1, and G2 have been reported to be the most potent with aflatoxin B1 (AFB1) posing the highest degree of carcinogenicity [57]. Aflatoxins are characterized by high melting points of 260˚C and a thermal degradation temperature of 269˚C [58]. This implies that aflatoxins exhibit high thermostability although they can be decomposed by strong oxidizing agents. Aflatoxin metabolism plays the biggest role in determining the degree of toxicity in animal cells, especially in the liver [57]. The liver is considered the principal target organ for aflatoxins based on the first pass effect [59]. Since AFB1 is the most biochemically reactive, most research is focused on its metabolic pathways which justify its carcinogenic properties [57]. When aflatoxins are absorbed by the liver, they undergo biotransformation where AFB1 is metabolized through activation by cytochrome P450 enzymes to form the intermediate adduct AFB1-8, 9-epoxide. Characterized by its low stability, this adduct is responsible for the covalent modification of DNA, preferentially at the N7 position of guanine bases thereby affecting the complementary base pairing mechanisms [30]. Besides DNA modification, AFB1-8, 9-epoxide undergoes base-catalyzed reactions to form a more stable AFB1- 8, 9-dihydrodiol which is reported to be the most mutagenic metabolite [35]. In addition, Kellerman et al. reported that AFB1 can also be bio-activated to a highly active and labile intermediate AFB1 2, 3-epoxide, which reacts with various nucleophiles in the cell besides binding with DNA, RNA, and proteins [60]. Furthermore, according to [30]. Yunus et al. AFB1 can also be converted to hydroxylated metabolites (via monooxygenase’s) which are then metabolized to glucuronide and sulfate conjugate in the endoplasmic reticulum. Consequently, aflatoxicosis results in mutagenesis, carcinogenesis, and teratogenesis due to the alkylation of nuclear DNA by highly electrophilic adducts. In addition, chronic aflatoxicosis culminates into reduced protein synthesis, production of essential metabolic enzymes and structural proteins for growth [30] and immunosuppression hence poor poultry performance [61].

Aflatoxin Prevalence in Poultry Feeds

Aflatoxins are produced on a wide range of food commodities especially cereals and oilseeds which are the key ingredients in livestock feed formulation [62]. Identified as the third most consumed cereal worldwide [63], maize is most likely to be contaminated with aflatoxins at higher levels than any other feed ingredients [64]. Consequently, most of the maize-based poultry feeds in Uganda are highly contaminated with aflatoxins beyond recommended levels of 20 ppb [18]. The key predisposing factor to poultry feed contamination is poor post-harvest handling of maize which leads to high contamination levels by Aspergillus Flavus [65]. Such practices lead to high levels and prevalence of aflatoxin contamination in maize [66]. In addition, poultry feeds are stored at a relative humidity between 80% - 90% which is within the optimum range for fungal development [66]. Such conditions render the stored feeds more susceptible to fungal attacks within the normal feed storage time [32]. Whereas fungal contamination depends on postharvest handling, fungal development and aflatoxin production are dependent on storage time [66]. This implies that, as traders tend to hold maize back waiting for better market prices after harvest, high aflatoxin contamination is inevitable. Consequently, in an attempt to mitigate the aflatoxicosis-induced production declines, the Food and Drug Administration legislations set up an action level of 20 ppb as the maximum residue limit allowed in poultry feeds [67].

Effects of Aflatoxicosis on Poultry Performance

Effects of Aflatoxins on Chicken Physiology: Due to the heavy aflatoxin contamination of feed ingredients, commercial poultry is highly susceptible to chronic and acute aflatoxicosis [5,68,38]. Whereas acute is associated with the consumption of highly contaminated feeds [51], prolonged consumption of feeds with relatively low aflatoxin contamination levels is associated with chronic aflatoxicosis [69]. As a consequence, chronic aflatoxicosis is associated with poor feed utilization and increased susceptibility to microbial stress which is reflected in performance declines [70,47]. Furthermore, chronic aflatoxicosis has been reported to be the primary cause of teratogenicity, carcinogenicity, and mutagenicity as well as growth inhibitory effects in poultry [71]. These defects, therefore, result in biochemical, hemato [72] logical, and immunological alterations in the chronically affected poultry [73,74].

Effects of Aflatoxicosis on Feed Intake, Energy and Amino Acid Utilization: While feed intake and utilization are key determinants of poultry performance, aflatoxicosis has been reported to reduce feed acceptability, utilization, and enzyme efficiency [26,75]. In addition, aflatoxins interfere with calcium uptake and organic nutrient utilization in poultry while excess calcium impedes phytase enzyme activity due to insoluble complex formation with phytate phosphorous [76,77]. Furthermore, chronic aflatoxicosis decreases amino acid and energy utilization due to declines in cell metabolic efficiency [78]. Since the interaction between sulfur-containing amino acids and synthesis of aflatoxin B1-epoxide deter protein utilization and hence weight gain, it’s worth investing in available local options for sustainable aflatoxin decontamination for improved feed utilization [79].

Effects of Aflatoxicosis on Humoral Immunity and Organ Health: Besides hindering nutrient utilization, aflatoxicosis results in a reduction in antibody titers of Newcastle and Infectious Bursal disease as well as regression of the bursa of Fabricius [71]. This implies that, through regression of the bursa of Fabricius, aflatoxins interact with the T-cells to affect cell-mediated immunity in poultry to suppress vaccine efficacy [71]. In addition, a reversal in chemostatic inhibition of phagocytic abilities of leucocytes as well as heterophils has been reported to be associated with aflatoxicosis. Therefore, the synergistic effect of both antibody synthesis and phagocytotic suppression contributes to the increased response to environmental stress in poultry. Relative organ weight is a key indicator of organ health, whereas chronic aflatoxicosis has been reported to increase relative liver and kidney weights it results in the regression of the Bursa of Fabricius [80] In fact, the liver and kidney are considered to be the target organs for aflatoxicosis in all the affected species. As a consequence, the accumulation of nitrogenous wastes and aflatoxin metabolites results in histopathological changes as well as inflammatory thickening of the uterine mucosa in the tissues [80]. This implies that the reduced efficiency in nitrogenous waster excretion which results from liver and kidney damage greatly accounts for aflatoxicosis-related stress in poultry.

Effect of Aflatoxicosis on Layer Production and Eggshell Characteristics: Poultry layers are bred to convert feed nutrients into egg production rather than body muscles. Aflatoxicosis has been reported to reduce egg production without noticeable variations in layer weight gains [81,82]. Aflatoxicosis in layers has been reported to cause cytoplasmic vacuolation of the hepatocytes through impaired lipid transport and synthesis [83,84]. Such impairment is accompanied by lipid deposition in the liver, and suppressed lipid levels in the blood circulation [60]. This implies that aflatoxicosis induces phospholipid and cholesterol inhibition in the liver which results in far-reaching effects on layer performance [84]. Defined as the fastest bio-ceramic calcifying process among biological systems [85], eggshell strength is a key aspect in egg storage and transportation. However, aflatoxicosis has been reported to affect eggshell characteristics by interfering with the absorption and transportation of calcium and phosphorous [86]. In addition, aflatoxins have been reported to interfere with vitamin D3 metabolism [2,87] hence affecting calcium immobilization for eggshell development. Furthermore, chronic aflatoxicosis results in hepatic damage and a reduction in hepatic zinc levels in poultry [88]. Yet, the enzyme-dependent conversion of bone calcium into egg calcium is grossly affected by the generation and composition of zinc bicarbonate in blood circulation [89]. Therefore, in addition to aflatoxin decontamination, calcium supplementation through calcium bentonite clay inclusion may not only sequester aflatoxins but also possibly improve dietary calcium availability in layers.

Aflatoxin Decontamination Approaches: Whereas preventing feed contamination offers the best option it is practically impossible to get reasonable quantities of aflatoxin-free feeds. This implies that prevention of fungal contamination during harvesting and storage [11,90], as well as fungal growth inhibition, offer more practical solutions [11]. On the contrary, most of the poultry farmers in Uganda don’t produce their feed ingredients hence the lack of such phytosanitary adherence. This, therefore, leaves feed fortification and decontamination as the most practically viable option to control aflatoxicosis. Fortification of poultry rations with synthetic methionine alleviates aflatoxicosis-induced growth depression [91]. This is attributed to the ability of sulfur-containing amino acids to inhibit AFB1 mutagenicity and AFB1- epoxide synthesis during biotransformation [79]. Nevertheless, sulfur amino acids are some of the essential and limiting amino acids in poultry diets rendering this approach less cost-effective. Therefore, aflatoxin adsorption renders one of the most effective approaches since it reduces their bioavailability in the liver [11,22].

Consequently, since there is a relatively broader spectrum of nonnutritive aflatoxin sequestering feed additives decontamination remains an economically viable option. Besides amino acid fortification, biological approaches on the other hand can be used to absorb mycotoxins through enzymatic degradation and modification [92]. As a result, these characteristics led to the creation of biofilters for fluid decontamination and probiotics which also bind and remove aflatoxins [92]. However, such biological decontamination works mainly through sorption and enzymatic degradation making it a limited approach for biological systems [93]. Besides, biological control approaches developed for decontamination of aflatoxins in feeds have equally had limited attention and a multitude of criticisms as well [94]. Similarly, chemical decontamination using acids, salts, oxidizing, and reducing agents which require drying, and cleaning have equally had setbacks [11]. These setbacks are associated with the health decline of the animals and many chemical residues in animal systems [95]. However, Huwing et al. suggested that chemicals like calcium propionate successfully inhibited mold proliferation without affecting livestock health but with significant cost implications. For that reason, toxin decontamination using inorganic and chemically inert binders like some bentonites renders the most practical and economic approach.

Aflatoxin Decontamination Using Binders: The most cost-effective approach to aflatoxin decontamination known is deactivation using aflatoxin binders like activated carbon and bentonite clays [95,96]. However, the chemical structure of both the aflatoxin and the binder determines the effectiveness of adsorption and binder-aflatoxin compatibility [97]. The important characteristics of the adsorbent to be taken into consideration, therefore, include its physical structure, charge, pore size, and surface area [95] in addition to the inert effect on other livestock physiological processes. Consequently, given such requirements activated carbon and hydrated sodium calcium aluminosilicates (bentonites) stand out to be the most suitable candidates for aflatoxin decontamination. Identified as a general toxin adsorptive material with a high surface to mass ratio, activated charcoal has been reported to show great potential for aflatoxin decontamination in biological systems [98]. However, the effects of activated charcoal on livestock performance have been variable [11] while responses in poultry resulted in lower economic viability than clay-based binders [1]. Such challenges consequently rule out the possibility of using activated carbon as long as bentonite clays can technically substitute them. Aflatoxin decontamination by clay binders like bentonites on the other hand is associated with hygroscopicity, polarity, and solubility which favor aflatoxin intercalation with the bentonites in water [13]. This implies that, as the bentonite clay gets hydrated in the gastrointestinal tract, the polar water molecules weaken the interaction between the closely packed bentonite layers by lowering the charge density of the sequestered exchangeable cations such as Ca2+, Mg2+, Na+ and K+ [14]. Therefore, the mechanism of aflatoxin absorption is primarily through the exchangeable cations which neutralize the interlayer charges in aluminosilicates and are involved in the binding mechanism of aflatoxin B1 [21,13] and Hydrogen bonding [99,100]. Since hydrated sodium calcium aluminosilicates have a high affinity for aflatoxin specifically, this character results in the formation of strong aflatoxin-clay complexes hence adsorption [101]. However, the properties of bentonites vary from one geological deposit to another hence the need to test the efficiency of each batch of bentonites clays as aflatoxin detoxifiers [101].

Practical Methods of Aflatoxin Decontamination: The practicability of any aflatoxin decontamination approach depends on its effectiveness and the costs associated with its application. However, the application of physical, biological, and chemical methods of decontamination separately or in combination provides varying degrees of effectiveness [102]. While physical means are less practical, with biological methods the degrading microorganisms have limited degradation mechanisms and stability in the GIT at different pH levels [103]. This consequently leaves chemically inert bentonite clays as the most suitable adsorbents for aflatoxin sequestration. Defined as a smectite clay mineral generated from the crystallization of volcanic ash, bentonite clays adopt a sheetlike structure where double layers of tetrahedral sandwich an octahedral layer to make up individual sheets. They adopt negative charges which are derived from the replacement of Al3+ with divalent Ca2+ or Mg2+ ions. Then the sheets are interconnected by the exchangeable Na+ and Ca2+ whose predominance differentiates calcium bentonite from sodium bentonite [25]. Due to its absorptive and colloidal effects, bentonite is used as a filler in pharmaceuticals and oil purification as well as additives in livestock feeds. However, their utilization in livestock feeds is limited by the fact that their physiochemical properties which are its aflatoxin sequestration signature are highly variable hence the need for localized performance evaluations.

Characterized as hydrated sodium calcium aluminosilicates, bentonites effectively bind aflatoxins in the GIT hence preventing their absorption into the bloodstream [16]. Moreover, Hesham, et al. [ 23] and Shi, et al. [33] reported an improvement in body weight gain and feed conversion ratio of broilers fed on diets fortified with bentonites. Consequently, this effectiveness of bentonites is attributed to the expanding clay lattice, interstitial water, exchangeable cations hence the aflatoxin binding ability [14]. In addition, bentonites have been also reported to be efficient against a broad spectrum of mycotoxins making them more suitable for the most frequent cases of multi-contaminated feeds [104]. Using bentonite clays hence targets binding the aflatoxins and prevents them from being absorbed from the animal’s digestive tract, and then excreting them through the fecal matter [90,13]. Characterized by the ability to form stable complexes with aflatoxins at temperatures between 25 ºC and 37 ºC, bentonites clays are capable of adsorbing aflatoxins under the condition in the GIT [105] (Magnoli et al., ). As a result, certain bentonite at 0.5% inclusion levels was able to reduce aflatoxin bioavailability in broilers [21,23]. However, bentonite clays from several sources have been reported to improve pellet stability [11] and poultry performance through aflatoxin decontamination but with varying degrees of effectiveness [105]. This implies that the different bentonite deposits in the Albertine Graben region of Uganda can provide a potential solution to feed AF decontamination [105]. However, the variation in properties among bentonites warrants assessing the performance.

The Existing Knowledge Gap: The high affinity for aflatoxins by the bentonites justifies their utilization given the high levels of aflatoxin contamination in the poultry feeds [8]. However, the aflatoxin decontamination potential among bentonite clays is highly dependent on the geographical location and nature of the bentonite clay parent materials [105]. Consequently, there is inconsistent and insufficient information about the inclusion levels of the different bentonite clay in poultry diets [9]. In addition, none of the previous studies has compared commercial aflatoxin binders with other bentonite clays as well as establishing the optimum inclusion levels of Albertine bentonite clays. Yet, beyond certain optima, bentonite clays are hypothesized to hinder nutrient utilization alongside the negative effects of excess calcium for the case of calcium bentonite. Furthermore, due to the transfer of aflatoxins and their metabolites to poultry edible products and their effect on human health, efforts have been made to set contamination limits of 20 ppb. Therefore, studies towards the exploitation of this resource are necessary since Uganda is endowed with huge bentonite deposits in the Albertine region [9].

Conclusion

The authors systematic review of the available aflatoxicological studies in poultry whose products are the most widely consumed among livestock products demonstrates that the majority of the studies proved a significant effect of aflatoxicosis on commercial poultry performance, carryover in products, and hence human health. The relationship between egg production and aflatoxin decontamination indicates a great reduction in the laying performance of poultry layers due to chronic aflatoxicosis. The most effective approach to combating the effects of aflatoxicosis is the use of readily available innert adsorbents like bentonites. However, it may suggest that the inclusion of such adsorbents be informed by localized feeding trials.

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Drainage in Abdominal Surgery

Introduction

Since ancient times, surgical procedures have been associated with conditions, that have either the cause, or effect of evacuating liquid media, that are detrimental to the body. To achieve this effect, various devices, which fall under the collective name “drains”, have been gradually designed, described, and used. We call the drain a simple or more com-plicated aid or a whole system used to evacuate unwanted fluids from the body [1]. The application of various drains has been a part of the surgical activity since the days of Hippocrates, when various metal, bone, gauze or wick preparations and gauze combinations were used as means of passive drainage. The oldest record of the usage of drainage comes from Hippocrates himself (480-377 BC). He used a wooden tube to drain the empyema [2]. Today’s modern surgery is more advanced and precise - it chooses drainage itself and drainage systems according to clear criteria and purpose:

• They remove pathological liquid products (purulent fluids, intestinal contents, effusion, etc.)

• They remove loose intra-abdominal fluids (bile, pancreatic juices, lavage fluids) before they can cause complications.

• They have a restituting effect [1].

Characteristics of Drainage Systems and their Effectiveness

The shape of the drains can be straight or shaped. Curved drains are used in thoracic surgery, where they are applied after surgery on the diaphragm. The end of the drain that remains outside the body can be either funnel-shaped to connect to the connector (inserted from the outside) or beveled for easier passage through the chest wall (inserted during internal surgery) [3]. Drains are manufactured in various lengths and widths. The width of the drain can be marked either by a number according to the Charrier scale, or the so-called French units. On the Charrier scale, the number 1 is equal to 0.3 mm and each subsequent number is 0.3 mm larger (Figure 1) [2]. The most used sizes were found to be 28F, 32F and 36F in adults and 16F, 20F and 24F in children. Polyethylene catheters (Intracarth), “J” -shaped catheters are intended for neonatal age [4]. When choosing the size of the lumen of the drain and the various couplings, it is necessary to proceed from the laws applicable to the dynamics of gases and fluids. Poiseuille’s equation is assumed for the gas flow under the assumption of laminar flow. The air flow is directly proportional to the square of the drain radius. For humid air, which has a turbulent flow, the Fanning equation applies, and so the flow rate depends on the radius of the drain up to the fifth power of the radius [5].

Figure 1: Drain types –

a) Robinson drain,

b) Jackson-Pratt drain,

c) Silicone drain.

The Most Important Criteria for Drain Selection

Drainage efficiency (performance), biostability and biocompatibility are the most important criteria. Rubber hoses are nowadays rejected due to poor biostability and surface structure deficit. The only exception is their use in T-drainage. As a result of secondary structural changes in the drainage material, which are caused enzymatically, there is a progressive rigidity of the material with increasing storage time in the body. Prolonged intra-abdominal drainage with rubber drains can lead to intestinal erosions. PVC materials should be excluded due to insufficient biocompatibility [6].

Drainage Efficiency

The total flow of the drainage system is the sum of all the individual streams that flow through the openings in the wall of the collecting channel. The flow in the collecting channel is turbulent, and beliefs are formed. An important parameter is the relationship of the sum of the areas of all side holes of the drain (f) to the crosssectional area of the collecting channel (b). Mainly drainage with a large f:b ratio did not initially show any pressure drop. The side openings in the rear part of the collecting channel suck the most, proportionally more than the openings in the front part. In the experiment, the authors tested and evaluated 14 different drainage systems and the following conclusions were drawn:

1. The larger the diameter of the drain, the larger the volume flow. The volume flow is the same in each cross section of the tube.

2. Drainages with a square cross-section at the beginning of the stream show approximately the same volume flow when compared to drains of circular cross-section with the same cross-sectional area size.

3. For suction drainage, a certain wall resistance against collapse must be ensured.

4. With the same geometry, the larger the volume flow, the more side holes of the same size are located on the drain.

5. As the ratio of the sum of the areas of the side openings to the cross-section of the collecting channel increases, the drainage capacity increases [7].

Principles for Abdominal Drainage

Figure 2: Premises in which fluid accumulates in a lying patient –

a) Subphrenic space on the left,

b) Paracolic space on the left,

c) Douglas space.

The issue of abdominal drainage has undergone great development. The advantages and disadvantages of drainage, questions of when, how, and what to drain during operations are considered. However, there is some consensus. In elective or minor uncomplicated abdominal surgeries (appendectomy, cholecystectomy), most authors are inclined to recommend not draining the abdominal cavity. Drainage is always recommended for potentially complicated surgical procedures where complications may be expected. Drainage should never be conducted by the surgical wound - due to the weakening of the wound and the possibility of postoperative herniation at the site of the drain and the risk of possible infection of the surgical wound. In places where we do not see, the drain is placed by hand. Direct drainage of the drain with the anastomosis should be avoided [8]. The abdominal cavity is an enclosed space (abdominal compartment) bounded by a rigid posterior wall and anterior-moving muscular wall. Muscles form the abdominal cavity with their tension and with their activity participate in locomotion, participate in ventilation, etc. When draining the peritoneal cavity, it is necessary to be aware of the most common places of fluid accumulation (Figure 2). In the vertical position, the lowest stored area of the abdominal cavity is the Douglas space, in the horizontal position the subphrenic space on both sides and also the Douglas space [9].

In the vertical position, the lowest stored area of the abdominal cavity is the Douglas space, and in the horizontal position the subphrenic space on both sides and also the Douglas space. The circulation of fluid between these three spaces is given by the intraabdominal pressure and the gravity of the fluid (Figure 3). The activity of the abdominal muscles is reflected in the change in intraabdominal pressure. In addition to muscle contraction, the increase in intra-abdominal pressure may be caused by acute visceral distension [9,10]. The resting intra-abdominal pressure in the horizontal position reaches values in the range of 0.78-1.5 kPa (8- 15.3 cm H2O). At the stand, the pressure increases due to gravity up to 2.94 kPa at the bottom of the Douglas space. During respiration, the intra-abdominal pressure changes by about 0.4 kPa, but with a severe cough, it can reach values of up to 14.7 kPa (150 cm H2O) [10]. The pressure changes resulting from respiratory movements are greater in the right hypochondria due to the position of the liver than in the left. Data on intra-abdominal pressure in the early postoperative period after laparotomy are interesting. While the intra-abdominal pressure is around 2 kPa on the first postoperative day, the fourth postoperative day can reach up to 6 kPa (61.2 cm H2O). Changes in intra-abdominal pressure also occur during artificial lung ventilation and are reflected in a higher incidence of laparoscopic wound dehiscence. Based on a number of experimental and clinical studies in the 1990s, intra-abdominal hypertension has been shown to cause abdominal compartment syndrome, which is often observed in clinical patients and in patients after severe abdominal trauma [11,12]. An increase in the content of the abdominal cavity as well as the retroperitoneum contributes to the increase of intra-abdominal pressure. Intra-abdominal pressure is transmitted to adjacent areas and has adverse effects on cardiac output, pulmonary ventilation, renal function, and cerebrospinal pressure. Increasing intra-abdominal pressure has an adverse effect on visceral perfusion. The more the intra-abdominal pressure increases and the longer this increase lasts, the more the blood flow through the splanchnic area decreases, which is reflected in the lowering of the pH of the intestinal mucosa [13].

Figure 3: Directions of possible fluid propagation in the abdominal cavity (left) Areas where fluid usually accumulates (right) a) a - Subhepatic space,

b) b - Subphrenic space on the right,

c) c1, c2 - Subphrenic space on the left,

d) d - Paracolic space on the left,

e) e - Douglas space.

Consequences of increasing intra-abdominal pressure:

1. At values <1.33 kPa (100 mm Hg = 13.6 cm H2O), blood pressure and cardiac output are within normal limits, but visceral blood flow is significantly reduced.

2. At 1.99 kPa (15 mm Hg = 20.4 cm H2O) cardiovascular changes already occur.

3. Renal dysfunction and oliguria may occur at values> 2.66 kPa (20 mm Hg = 27.2 cm H2O).

4. Anuria occurs at values> 5.32 kPa (40 mm Hg = 54.4 cm H2O). Abdominal compartment syndrome is characterized by increased inspiratory pressures, decreased cardiac output, oliguria, despite normal or increased cardiac pulmonary pressure. Clinically significant intra-abdominal hypertension is observed in many conditions such as e.g., in postoperative intra-abdominal bleeding, in complicated intra-abdominal vascular surgery, in liver transplantation operations, in advanced diffuse peritonitis, in severe acute pancreatitis, in severe abdominal trauma, but also in peritoneal insufflation during laparoscopic patients and in laparoscopic patients. with liver cirrhosis [14]. Properly placed drain drains fluid from the abdominal cavity either passively (after a slope, with the participation of intra-abdominal pressure) or active. In any case, it is necessary to guide the drain as short as possible from the drained bearing to the body surface. Therefore, some authors recommend first placing the drain in the drained area (cavities, bearings) and only then take the drain out of the surgical wound, in the place where the drain itself is placed on the abdominal wall [15]. Targeted is the drainage of a certain demarcated area, where any fluid (bile, blood, pancreatic juice, etc.) is drained.

Drains established near anastomoses can be the first to inform us about possible suture insufficiency - signal drains. Active drainage is usually not recommended near anastomoses. The most commonly used closed drainage system in visceral surgery is Robinson drainage (Figure 4), which consists of a 20F silicone hose with a length of one meter. The end, which is placed in the abdominal cavity, has several holes on the sides and the opposite end is connected to a plastic calibrated bag with a volume of 350 ml. This system is modern and highly hygienic, it also contains a shut-off valve that does not allow ascending infection [16]. Infectious complications associated with bacterial contamination of the drain are one of the most important risk factors for intraabdominal drainage. Gastric surgery, such as early suture and ulcer sealing, gastric resection BI or BII, vagotomy, require drainage of the operating room. If a drain is laid, then it usually slopes into the subhepatic space or Redon’s drain (Figure 5).

Figure 4: Robbinson’s drain.

Figure 5: Robbinson’s drain.

Based on a German questionnaire survey, Böhm found out that 90% of them would introduce drainage after gastrectomy. Drains are most often established in the area of anastomoses, subhepatic space or in the area of the duodenal stump. The average length of drainage was 5.5 days. The suture of the ulcer was always sealed with a suture [17]. Drainage of the duodenal stump area depends on the anatomical conditions, the type of disease, the complexity of the resection and the type of duodenal stump closure. If the operating surgeon is in doubt, then he drains the duodenal stump area always sufficiently and effectively. The prognosis of early dehiscence of the duodenal stump is a very serious complication with high lethality - up to 50% [18]. After the patient’s condition improves, the fistula usually heals spontaneously. The abdominal cavity is still secured by laying a slope drain under the liver.

Use of Drainage in Small and Colon Surgery

In simple resections of the small intestine (Meckel’s divertuculus), drains are usually not established. In the case of acute small bowel surgery, e.g., due to Crohn’s disease, then it always drains. The most common indications for surgical treatment in Crohn’s disease are complications in terms of fistulations, especially in the ileocecal region [19]. Abdominal drainage after colorectal operations depends on the type of operation (acute, elective) and the scope of the operation. It is not recommended that the drain lean against the intestinal wall (Figure 6). The abdominal cavity drains only in cases of major damage to the serous surface of the intestinal wall or exposure of the lymphatic system in the retroperitoneum. In these cases, drainage is established in the area after the resected colon ascendens and/or in the Douglas space, usually for 48-72 hours. Drainage is always recommended for operations on the left half of the colon and rectum, even if no positive effects of prophylactic drainage after colonic elective procedures have been found in control studies [20]. In the case of rectal amputations, it is advantageous to introduce Redon drainage into the resulting cavity through the perineum. Usually, two drains are introduced. Böhm and co-workers report that 90% of surgeries in Germany drain the abdominal cavity after resections of the esophageal loop. They usually drain the Douglas area (54%) or the anastomosis area (31%). The average length of drainage was 5.6 days [17].

Figure 6: Drain position to intestinal suture –

a) Incorrect,

b) Correct (drain should not insist on anastomosis).

After rectal resection, it is recommended to drain the anastomosis area. This is possible either by the retroperitoneal or peritoneal route (Figure 7). In this case, the drains perform a signal function. Some literature data emphasize the importance of purging the presacral space after rectal surgery. After rectal extirpation, the perineum is actively drained using Redon’s drains. Larger calibers are chosen - usually No. 12. It is led out of the perineum forward so that the patient does not lie on them. Miles initially closed the perineal wound primarily. Active drainage was not yet known, and ascending infections arose from the catchment drainage. Miles solved this by introducing open aftercare in the form of so-called “packing” - longs placed in a thin foil. The healing process was very lengthy. Secondary healing is always very unpleasant for the patient. Today, this method is no longer used, and after rectal extirpation, primary closure of the perineal wound is always indicated. Active drainage is started at the end of the operation.

Figure 7: Drainage after low rectal reaction. Drain taken retroperitoneally.

Drainage in the Pancreas

After resection operations on the pancreas, gravity drains stored in the environment are used. Surgery is most often indicated in acute pancreatitis due to signs of peritoneal irritation or septic condition. If the patient is operated on due to the edematous form of pancreatitis, bile duct remediation with possible decompression and drainage of the omental bursa is usually sufficient. In the necrotic form of acute pancreatitis, we perform neurectomy and thoroughly drain the area after the slope [21]. In these cases, drains with a wider diameter are used to prevent their early clogging by necrotic masses. It is also possible to establish a flush lavage exchange.

Individual Types of Drainages Used in the Intra- Abdominal Inflammatory Process

Percutaneous Drainage

Percutaneous drainage is inserted under CT control or ultrasound [22]. The most common drained deposits are abscesses in the area of peritoneal cavities, intra-parenchymal deposits (liver and pancreas abscess), or retroperitoneal abscesses. Other puncture lesions are most often cysts or pseudocysts of the pancreas. The best results can be achieved by evacuating well-defined small deposits with a low viscosity content. Contraindications to percutaneous drainage include cystic or necrotic tumors, abscesses around foreign bodies, abscesses associated with intestinal fistulation. The trocar technique means direct puncture with a drainage set after the previous targeting. It is always necessary to send a sample for bacteriological and cytological examination. For secretions of lower content, drainage with a lumen of 8-10 F is sufficient, for denser secretions of 10-14 F, exceptionally, a lumen of 16-18 F is used. it is necessary to monitor the amount of secretion, check the correct introduction of the drain into the drained deposit, or the amount of residual secretion in it (CT, ultrasound, sciascopy). With the correct technique of percutaneous drainage, the efficiency is in the range of 80-90%, lethality up to 1%.

Laparoscopic Remediation of An Inflammatory Deposit with Standard Drainage of the Abdominal Cavity

In some workplaces, for example, gastroduodenal ulceration with peritonitis, small pelvic abscess, tutorial abscess, resp. pelviperitonitis. We can also treat perforating appendicitis in this way. Proponents of laparoscopy say that perioperative lavage is more effective in laparoscopy than in laparotomy surgery if the abdominal fold is better defined. The main advantage of this method is the minimal trauma of the abdominal wall, there are no possible complications of a severe infection, organ emergencies, etc. [23].

Closed Continuous Peritoneal Lavage

The authors of this method (Beger, McKenna) are based on the concept of peritoneal dialysis [24]. Enclosed continuous peritoneal drainage is shown in (Figure 8). They involve continuous cleansing of the cavity of toxins, blood residues, bile, or other secretions, including active enzymes. Repeated laparotomy is usually not necessary. The disadvantages are mainly the loss of proteins (especially albumin - about 1 g / l solution) and electrolytes, we cannot prevent drainage and obliteration of the drainage spaces with the risk of the formation of limited deposits of residual infection. Indications for this type of drainage include diffuse peritonitis, locally large abscesses (over 0.5l) and non-controlling pancreatitis. Standard laparotomy, removal of necrosis, evacuation of purulent deposits, and lavage of the area are followed by insertion of two to four thin catheters into the inflammatory area or fluid collection. From this area, the fluid is then drained through four to six (according to some authors up to 11) thick drains placed on the base of the abdominal cavities or directly into the area of inflammation (e.g., peripancreatically). It is advantageous to use two-way drains (Tenckhoff), due to the current lavage and drainage. Continuous lavage in the abraded cavity with a volume of about 1 liter per hour is performed with a solution intended for peritoneal dialysis.

Figure 8: Closed continuous peritoneal lavage - drainage areas in both directions

a. Subhepatic space,

b. Subphrenic space on the right,

c. Subphrenic space on the left,

d. Pericolic space on the left.

e. Douglas space,

f. Drain to the gastric major of the stomach,

g. Drain to the radix of the mesentery.

Conclusion

Drainage systems are a common part of postoperative surgical management and are used to remove fluid collection from the abdominal cavity. The drain may be superficial in the subcutaneous tissue, or deep in the organ or cavity. The number of drains depends on the scope and type of operations. Intraabdominal drainage improves early detection of complications (gastrointestinal leakage, bleeding, bile leakage), prevents fluid or pus accumulation, reduces morbidity and mortality, and shortens hospital stay. The aim of this review was to evaluate the evidence supporting the systematic use of abdominal drainage. Abdominal drainage is not easy, especially due to more complicated anatomical conditions and the presence of consciousness and intestinal loops. Very quickly after the insertion of the drain, they envelop the drain and sometimes make it functional. This is even more true for abdominal vacuum drainage. Fluid (this also applies to the abscess) tends to accumulate in the abdominal cavity at certain predilection sites (Douglas space, retroperitoneal space, subphrenic spaces, subhepatic space, paracolic spaces - depending on the patient’s position), so the surgeon’s decision to drain is in place and most often applies to these areas. Tubular drains made of biocompatible inert material are most suitable for abdominal drainage. Their location has drainage success, especially when stored in preformed areas or near parenchymal organs, to minimize the possibility of clogging with momentum or intestinal loops. Due to the nature of the effusion that is resolved by abdominal drainage, the expected drainage fluid content, and other factors, in addition to the simple tubular drain after abdominal surgery, other drainage systems are used, as mentioned above.

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