A 48-year-old woman comes to the hospital for elective cholecystectomy. The patient has had postprandial upper abdominal pain and nausea for the past several months, and ultrasonography revealed gallstones. After discussion of risks and benefits, laparoscopic cholecystectomy was planned. Her other medical conditions include obesity and hypertension. In preparation for the surgery, general anesthesia with endotracheal intubation is administered. Immediately after a needle is placed into the intraperitoneal space and CO₂ gas insufflation is performed, severe sinus bradycardia and transient atrioventricular block is noted. Which of the following is the most likely cause of the observed intraoperative finding in this patient?

Question

Quizplus · Accepted Answer

Laparoscopic intervention is a minimally invasive option for a number of intraabdominal surgeries (eg, cholecystectomy, hysterectomy). Preparation for the surgery requires insufflation of CO₂ gas into the abdominal cavity to create space for surgical maneuvering and to facilitate adequate camera visibility during the procedure. CO₂ is introduced into the abdomen via a needle or port, with continuous monitoring of intraabdominal pressure. Peritoneal stretch receptors sense the increase in intraabdominal pressure and respond by triggering increased vagal tone. Close monitoring is required as patients may develop severe bradycardia, atrioventricular block, and sometimes asystole. The increased intraabdominal pressure can also cause a mechanical increase in systemic vascular resistance leading to elevations in blood pressure. (Choice A) CO₂ gas embolization is a rare complication of CO₂ insufflation, usually resulting from inadvertent insertion of the insufflation needle directly into an artery, vein, or organ (eg, liver). Affected patients typically develop end-organ infarction (arterial embolism) or hypotension and obstructive shock (venous embolism). Severe bradycardia and atrioventricular block are not expected. (Choice B) Agents used for general anesthesia (eg, propofol) commonly have a cardiac suppressive effect; therefore, inadequate anesthesia is expected to cause tachycardia rather than bradycardia. (Choice D) Systemic absorption of intraabdominal CO₂ can occur during laparoscopic procedures, leading to an increase in blood PaCO₂. This causes peripheral vasodilation with a reflexive increase in heart rate. (Choice E) Vena cava compression can result from high intraabdominal pressure; however, monitoring of intraabdominal pressure makes significant compression unlikely. In addition, caval compression would lead to decreased venous return with a reduction in cardiac output and a reflexive increase in heart rate. Educational objective: Laparoscopic intraabdominal surgery (eg, cholecystectomy) requires insufflation of CO₂ into the abdomen to create space for surgical maneuvering and visibility. The increased intraabdominal pressure stimulates stretch receptors on the peritoneum that respond by triggering an increase in vagal tone. Consequently, patients can develop severe bradycardia, atrioventricular block, and sometimes asystole. References: Bradycardia as an early warning sign for cardiac arrest during routine laparoscopic surgery. (http://www.ncbi.nlm.nih.gov/pubmed/26424701)

A 48-Year-Old Woman Comes to the Hospital for Elective Cholecystectomy