QUESTIONS

1. Describe the natural drainage of the peritoneal cavity (don't forget the lacunae of the diaphragm).
    
2. What natural defense mechanisms does the peritoneum have?  How is each helpful?
    
3. For each potential defense mechanism listed below, explain how it can work against the body instead of for it.
   
   a) lymphatic drainage system
   
   b) fluid efflux
   
   c) adhesion formation
   
   d) ileus
    
4. Is chyle particularly irritating to the peritoneum?  How about bile?
    
5. When doing a diagnostic lavage of the peritoneum, how much saline should you infuse into the abdomen? What do you look for in the fluid that you get back out that would indicate surgery?
    
6. Banamine is advocated for endotoxic shock by many. What does it do and how should you use it?
    
7. Naloxone is also advocated.  Why and how is it used?
   
   
   
   
    

ANSWERS

1. On the visceral surface of the diagphragm there are special lymphatic collecting vessels called "lacunae". There are also small stomata in the diaphragm between mesothelial cells which direct fluid to the lacunae. This drainage goes from the peritoneum to the retrosternal & anterior mediastinal lymph nodes. Fluid in the peritoneum is moved towards these pores by the diaphragms movements, muscle tone etc. Circulation sweeps cranially.
   
   
   
   
    
2. Peritoneal fluid is not very bacteriostatic but it does have fibronectin in it which non-specifically opsonizes bacteria. The mesothelium of the peritoneum is easily damaged & forms adhesions rapidly in an effort to localize infection.  The omentum also helps localize inflammation.  There is an efflux of fluid into the peritoneum to dilute any inflammation and any antigenic material is rapidly swept up in the lymphatic system described above & presented to the immune system.    There are reflexes to initiate muscle rigidity in the diaphragm, however, which tend to reduce lymph drainage the idea being to confine an infection to the peritoneum where it can be localized by adhesions. Ileus similarly occurs mediated by the sympathetic nervous system in an effort to further reduce the circulation of the peritoneal fluid.
   
   
   
   
    
3. a) bacteria may be swept up in the lymphatic drainage system & gain access to other areas of the body thus promoting septicemia.
   
   b) Efflux of fluid at first dilutes toxins but the patient can lose a great deal of fluid into the peritoneum (not to mention serum protein).
   
   c) Adhesions can block lymphatic drainage, strangulate organs and allow sequestration of infection.
   
   d) Ileus allows pooling of fluid inside the gi tract and promotes bacterial leakage out of the bowel.
   
   
   
   
    
4. Both bile & chyle are very irritating to the peritoneum. Other irritants include gastric secretions/acid, pancreatic juice, urine, and barium.
   
   
   
   
    
5. 20 ml/kg saline is a good amount to add. Surgery is indicated if you see WBC > 300/cubic mm, bacteria esp if intracellular, food particles, or if the fluid has elevated creatinine or bilirubin. (but control endotoxic shock first, of course.)
   
   
   
   
    
6. Banamine (flunixine meglumine) reduces thromboxane A2 & PGI2 - inflammatory mediators of toxic shock. In the article I read they recommended an IV bolus of 1.1 mg/kg q 3-4 hours.
   
   
   
   
    
7. Same as in pancreatitis. Beta endorphin is produced by the pituitary in stress. It causes cardiovascular depression, hypotension, resp depression - all of which contribute to shock. Naloxone antagonizes these effects & synergizes with endogenous steroids. The dose I have is 1-2 mg/kg bolus IV followed by a drip of 1-2 micrograms/kg per hour.