PRINCIPLES OF EMERGENCY ANESTHESIADr Masood Entezari

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

Further problems : - dehydration

- electrolyte abnormalities - hemorrhage

- pain The components of general anesthesia are the

same in elective and emergency surgery

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)

CLASSIFICATION OF OPERATIONS

Emergency

immediate operation within one hour of surgical consultation and considered life – saving , for example, ruptured aortic aneurysm repair

Urgent Operation as soon as possible after resuscitation , usually within 24 hour of

surgical consultation , for example , intestinal obstruction

Scheduled Early operation between 1 and 3 weeks , which is not immediately life – saving , for example, cancer surgery, cardiac surgery

Elective Operation at the time to suit both the patient and surgeon

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

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

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

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

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

Some basic requirements for endoteracheal intubation:

- skilled assistance must be present - the trolley must tip

- the suction apparatus must work correctly and be left 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

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

using the correct anesthetic technique (rapid sequence induction)

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

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

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

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

Suxamethonium has many side effects but remain the best drug available

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

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

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

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)

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

CONCLUSION

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

surgery