Principles of emergency anesthesia

2. Principles of emergency anesthesia Dr Masood Entezari

3. Introduction • In elective surgery: - madding correct diagnosis - identifying and treating medical disorders - occurring an appropriate period of starvation • One or more of these conditions are often not met in emergency work

4. Further problems : - dehydration - electrolyte abnormalities - hemorrhage - pain • The components of general anesthesia are the same in elective and emergency surgery

6. The key to success in emergency anesthesia is a thorough preoperative assessment • Particular attention must be given to: - the search for medical problem - the occurrence of hypovolemia - an evaluation of the airway • There are very few patients whose clinical state is so life – threatening that they need immediate surgery ( true emergency)

7. Classification of operations

8. The vast majority of patients benefit from : - the correction of hypovolemia - the correction of electrolyte abnormality - stabilization of medical problem - waiting for the stomach to empty • When to operate is the most important decision that has to be made in emergency work • Emergency anesthesia ≈ general anesthesia • But

10. Due to the increasing use of regional anesthesia , hypovolemia must be corrected pre- operatively • The sedated patient can talk to the anesthetist at all time • If not ,then airway control may be lost with the risk of aspiration of gastric contents

11. Full stomach • Starvation for at least 4-6 hours in emergency surgery • All emergency patients should be treated as having a full stomach and so at risk of vomiting , regurgitation and aspiration • Occurring the vomiting at the induction and emergence from anesthesia • Entering gastric acid to the lungs and creating a pneumonitis can be fetal

12. Silent regurgitation : passive regurgitation of gastric content up to esophagus • Regurgitation is particularly likely at induction of anesthesia when several drugs used • Regardless of the period of starvation ,in emergency anesthesia there is always a risk of aspiration

13. The trachea must be intubated as rapidly as possible after induction • Endoteracheal intubation is performed under general anesthesia when there is no problem in preoperative assessment of the airway

14. Some basic requirements for endoteracheal intubation: - skilled assistance must be present - the trolley must tip - the suction apparatus must work correctly and beleft on - a rang of sizes of endoteracheal tubes must be available - spare laryngoscopes must be available - ancillary intubation aids, gum elastic bougie and stillettes must be available

16. Neither physical nor pharmacological methods should be relied on to empty the stomach completely • In some specialties (obstetrics) an H₂ receptor blocking drug and 30 ml sodium citrate used orally 15 minutes before induction of anesthesia • Opiates delay gastric emptying and increase the likelihood of vomiting

17. using the correct anesthetic technique (rapid sequence induction)

19. preoxygenation • Breathing 100% oxygen for at least 3 minutes before induction • In breathing oxygen only, the lungs denitrogenate rapidly and after 3 minutes contains only oxygen and carbon dioxide • There is a greater reservoir of oxygen in the lunges to utilize before hypoxia occurs

20. Cricoid pressure • Identifying the cricoid cartilage on the patient before induction of anesthesia • Warning the patient that they might feel pressure on the neck as they go to sleep • Pressing down on the cartilage continuously until telling the anesthetist to the assistant for stopping

23. Object: compressing the esophagus between the cricoid cartilage and vertebral column • Pressure is usually undertaken by firm but gentle pressure on the cartilage by the thumb and forefinger of the assistant • The cricoid is easily identifiable , forms a complete tracheal ring , and the trachea is not distorted when it is compressed • Giving a neuromuscular blocking drug to facilitate intubation

24. Intubation • The neuromuscular drug must act rapidly and have a short duration of action • The lungs are not ventilated during a rapid sequence induction ; this will prevent accidental inflation of the stomach , which will further predispose the patient to regurgitation and vomiting • An agent with a short duration of action is valuable because in cases of failed intubation spontaneous respiration will return promptly

25. Suxamethonium has many side effects but remain the best drug available

26. Releasing the cricoid pressure only when : - the trachea is intonated - the cuff inflated - the correct position of the tube is confirmed • The anesthetic is maintained with : - a volatile agent - nitrous oxide - oxygen - competitive relaxant - suitable analgesia

27. The reversal of the relaxant at the end of the procedure is undertaken with the anticolinesteras (neostigmine) • Atropine or glycopyrrolat is given concomitantly to stop bradycardia occurring from the neostigmine • Major disadvantage of potential hemodynamic instability of rapid sequence induction: hypertension and tachycardia following laryngoscopy and intubation • This is more severe in urgent surgery than elective surgery because of using opiates at intubation of anesthesia

28. Other indications for rapid sequence induction • Every anesthetic ,not just emergency work , should be considered from the point of view of unexpected vomiting or regurgitation • Some cases are at high risk and rapid sequence intubation should be considered carefully as an option in this group

30. Pulmonary aspiration • Pulmonary aspiration may be obvious • Silent pulmonary aspiration is presenting as a postoperating pulmonary complication • Treatment : »suction of airway »oxygenation of the patient(priority) » broncoscopy (may be required)

32. If the patient is not paralyzed , surgery permitting, he or she should be allowed to wake up • If paralyzed , intubation and ventilation must occur and oxygenation maintained • Bronchospasm may be treated with aminophylline • Further treatment may include antibiotics , other bronchodilators and steroids • Aggressive early management is required

33. Conclusion Anesthesia for emergency surgery needs careful preoperative assessment and adequate resuscitation must be undertaken before surgery