Complications of Anaesthesia MCQs

PONV is the second most common complaint from patients after surgery (postoperative pain is the number one complaint). Of the many independent predictors of PONV in adult prospective studies, female gender is the strongest predictor for PONV and the need for postoperative antiemetic rescue treatments. It is interesting to note that although patients often experience nausea when smoking their first cigarettes, smokers have a lower incidence of PONV compared to nonsmokers. Other predictors of PONV include nonsmokers, previous history of PONV, history of migraine headaches, use of post[1]operative narcotics, lengthy surgical procedures, use of nitrous oxide, and the use of volatile anesthetics Reference: Miller: Miller's Anesthesia, ed 8, pp 2947-2954.

This patient is demonstrating clinical features of a tension pneumothorax with hypoxia, elevated airway pressures and hypotension. This is a recognized risk of laparoscopic surgery and requires immediate recognition and treatment with insertion of a cannula in the second intercostal space, midclavicular line on the affected side. An intercostal chest drain should then be inserted for this life-threatening emergency. Optimizing ventilator parameters would not treat the cause and may worsen any tension by increasing the size of the pneumothorax. Administration of intravenous fluid boluses would be of benefit but would not be addressing the underlying cause. Reference: Hayden P, Cowman S. Anaesthesia for laparoscopic surgery. Contin Educ Anaesth Crit Care Pain 2011; 11:177–180.

Hyperventilation to Paco2 of 20 mm Hg or higher for more than 2 hours will result in active transport of HCO3 - out of the CNS. This results in spontaneous breathing at a lower (not higher) Paco2. The other choices should be included in the differential diagnosis of apnea. Reference: Hines: Stoelting's Anesthesia and Co-Existing Disease, ed 5, pp 359-361; Miller: Basics of Anesthesia, ed 6, pp 62-64, 340; Barash: Clinical Anesthesia, ed 7, pp 271-273.

Cerebral oxygen consumption decreases by approximately 7% per degree Celsius decrease in temperature. Hypothermia is associated with delayed drug metabolism, increased blood glucose, Vasoconstriction Impaired coagulation postoperative shivering accompanied by tachycardia and hypertension, and Increased risk of surgical site infections. Reference: Morgan and Mikhail’s clinical anesthesiology 6th edition pg 132.

Anesthetic agents that release histamine directly include Atracurium, Mivacurium, Morphine and meperidine. They cause histamine release, mainly cutaneous when used in patients. Betablockers can increase airway reactivity and may interfere with the activity of beta agonists. Hence, they are avoided in asthmatic patients. Reference: FRCA A TO Z , page no 277

Malignant hyperthermia (MH) is a life-threatening hyper metabolic state of skeletal muscle that is triggered by the volatile inhaled anesthetics isoflurane, desflurane, and sevoflurane and by the depolarizing muscle relaxant succinylcholine. Malignant hyperthermia presents as an increase in carbon dioxide production, acidosis, cardiac arrhythmias, muscle rigidity, and hyperthermia. Death can occur if the MH crisis is not managed appropriately and early in the course of the episode. The mainstay of treatment is I.V. dantrolene. Reference: stoelting’s anaesthesia and coexisting diseases sixth edition pg 635

Malignant hyperthermia (MH) is a life-threatening hypermetabolic state of skeletal muscle that is triggered by the volatile inhaled anesthetics- Isoflurane Desflurane Sevoflurane Depolarizing muscle relaxant succinylcholine Malignant hyperthermia presents as an increase in Carbon dioxide production Acidosis Cardiac arrhythmias Muscle rigidity Hyperthermia Death can occur if the MH crisis is not managed appropriately and early during the episode The mainstay of treatment is i.v . Dantrolene Of the inhaled anesthetics, only nitrous oxide is not contraindicated in malignant hyperthermia Reference: stoelting's anaesthesia and coexisting diseases sixth edition pg 635; Drugs in Anesthesia and Intensive Care, Edward Scarth, Susan Smith 5th edition pg 278.

Pneumocephalus is a recognized complication of surgery in the sitting position. During surgery, various techniques may be used to reduce the volume of the brain which encourages air to enter the intracranial space and, when the cranial cavity is closed and the brain expands, the air is compressed causing a mass effect with elevated ICP. The condition is worsened with the use of nitrous oxide since it has increased solubility in blood, leading to expansion of air bubbles. Reference: Morgan and Mikhail's clinical anesthesiology 6th edition pg 606.