Definition

Although a laparoscopic technique is minimally invasive with regard to wound healing time, postoperative pain, length of hospital stay, and patient satisfaction with cosmetic effects, it significantly interferes with normal physiology. Physiologic changes during laparoscopy result from the combined effects of abdominal insufflation, Trendelenburg (head-down) or reverse Trendelenburg (head-up) position, systemic absorption of carbon dioxide (CO ₂ ) used to produce pneumoperitoneum, and the cardiovascular effects of general anesthesia. Administering safe anesthesia for laparoscopic surgery requires the anesthesiologist’s awareness of side effects and complications inherent in the laparoscopic technique.

Increased intraabdominal pressure caused by insufflation results in caval compression, reduced venous return, increased systemic and pulmonary vascular resistance, and an increase in left ventricular wall tension. Cardiac output decreases, mainly at the beginning of peritoneal insufflation. A decrease in left ventricular end-diastolic volume has been demonstrated by transesophageal echocardiography (TEE). However, cardiac filling pressures rise due to an increase in intrathoracic pressure during abdominal insufflation. The effects of abdominal insufflation on venous return and cardiac output are somewhat mitigated by the Trendelenburg position, but may be greatly exacerbated by the reverse Trendelenburg position, especially when combined with hypovolemia and vasodilation.

Pneumoperitoneum is accompanied by an acute neurohormonal response. Catecholamine and vasopressin release and the renin-angiotensin-aldosterone axis are activated and contribute to an increase in systemic vascular resistance. Renal blood flow, glomerular filtration rate, and urine output decrease during abdominal insufflation.

Ventilatory effects of pneumoperitoneum include reduced lung compliance, decreased functional residual capacity, and increased ventilation-perfusion mismatch. The Trendelenburg position favors the development of atelectasis. Reduced alveolar ventilation and CO ₂ absorption from the peritoneal cavity result in respiratory acidosis. Increased Pa co ₂ and the Trendelenburg position increase cerebral blood flow and intracranial pressure, as well as intraocular pressure, but the extent and clinical significance of these effects are currently unknown.

Arrhythmias occurring during laparoscopy have multiple causes. Tachyarrhythmias (sinus arrhythmias, atrial and supraventricular ectopic beats and tachycardias, ventricular ectopic beats, ventricular tachycardia or fibrillation) most frequently occur early during insufflation when hemodynamic disturbances are most intense. They also may be an early sign of venous gas embolism. Tachyarrhythmias occurring during established pneumoperitoneum may be due to hypercarbia and related catecholamine surge. Bradyarrhythmias (sinus bradycardia, wandering atrial pacemaker, junctional rhythm, atrioventricular heart block, asystole) are likely vagally mediated and secondary to a rapid increase in intraabdominal pressure, or due to severe respiratory acidosis. Pulseless electrical activity may develop in a setting of extreme hypotension, for example, when a combination of increased intraabdominal pressure and reverse Trendelenburg position critically interfere with venous return.

Incorrect placement of the insufflating needle (Veress needle) may result in extraperitoneal insufflation of CO ₂ . The incidence of subcutaneous emphysema in laparoscopic procedures is between 0.4% and 2%. Insufflation of CO ₂ may extend into the mediastinum and pericardium. Pneumopericardium may produce a clinical picture of pericardial tamponade. Pressurized gas also may dissect into the pleural space, either via natural peritoneal-pleural communications or after an accidental injury of the diaphragm, resulting in pneumothorax. Finally, inadvertent intravascular placement of the Veress needle during insufflation results in intravascular gas embolism. Minor vascular gas embolism can be detected by TEE in up to two-thirds of all patients undergoing laparoscopic cholecystectomy. CO ₂ is quickly absorbed and readily expired by the lungs, so the consequences of gas embolism with CO ₂ may be less severe. The lethal embolic dose of CO ₂ is five times greater than that estimated for air. However, an unrealized intravascular insufflation will result in a massive gas embolism that is usually lethal.

Placement of an abdominal trocar may result in an accidental bowel perforation or a solid organ or vascular injury, resulting in a severe hemorrhage that may initially go unnoticed. Control of hemorrhage during laparoscopy is difficult and usually requires emergency conversion to an open procedure. Decompression of the stomach with a gastric tube placed before abdominal insufflation is believed to decrease the risk of gastric perforation by the Veress needle or a trocar.

Rhabdomyolysis is a rare complication of prolonged surgery in the extreme Trendelenburg position. This complication probably results from a combination of decreased arterial perfusion of the elevated lower limbs, venous compression by leg supports, and impairment of femoral venous drainage by increased intraabdominal pressure.

The introduction of robotic surgery in 1999 has added another layer of complexity to the anesthetic management of laparoscopic procedures. The robot is bulky and it commands most of the operating room space. Its arms are rigid, so any patient movement during the procedure may result in a serious injury. Once the robot is docked in place, access to the patient in general, and to the airway in particular, is severely restricted, and adjusting the patient’s position on the operating table is no longer possible; therefore risk of position-related injuries and accidental loss of airway is increased. Robotic gynecologic and urologic procedures require an extreme Trendelenburg position and very high insufflation pressures, so hemodynamic and respiratory challenges of anesthetic management are exacerbated. Prolonged extreme Trendelenburg position may result in significant facial and upper airway edema. The incidence of corneal abrasion in robotic surgery appears to be higher.

Postoperative nausea and vomiting occur in 40% to 70% of patients after laparoscopy. Postoperative pain due to diaphragmatic irritation is usually localized to shoulder, neck, or upper abdomen.

Recognition

Vigilance and awareness of the potential complications of laparoscopic surgery and of their temporal relation to surgical maneuvers may help the anesthesiologist promptly recognize and manage those often serious and occasionally life-threatening events.

An acute decrease in chest compliance and hemodynamic instability may accompany abdominal insufflation and placing the patient in the Trendelenburg position at the beginning of the procedure. Reverse Trendelenburg positioning and an increase in abdominal insufflation pressure may cause additional hemodynamic instability at any time during laparoscopy. Close monitoring of hemodynamic parameters and ventilatory mechanics, with rapid response to any dynamic changes, is the essence of anesthetic management during these maneuvers.

Sudden hypotension may result from a combination of hypovolemia and high-pressure abdominal insufflation, especially in the reverse Trendelenburg position. Other possible causes, such as hemorrhage, bradycardia, and tension pneumothorax, just to mention a few, must be taken into consideration.

Peak inspiratory pressure (PIP) typically increases during and after abdominal insufflation. A gradual increase during insufflation is expected because of limited diaphragmatic excursion and reduced lung compliance. A sudden increase, however, should raise the suspicion for pneumothorax, which may be caused by diaphragmatic injury and communication between the pleural cavity and the insufflated peritoneal cavity, or by barotrauma of the lung. Differential diagnosis should include endotracheal tube (ETT) obstruction or main-stem migration. Lung auscultation, attempt at manual ventilation, passing a suction catheter down the ETT, fiberoptic tracheobronchoscopy, and analysis of the ETCO ₂ waveform are all useful in rapidly establishing the cause of acutely increased PIP.

Capnography is one of the most useful monitors during laparoscopy. It may provide early warning signs of impending catastrophic events. A sudden partial decrease in ETCO ₂ may be seen in low cardiac output or main-stem migration of the ETT, but also may mean venous air embolism, pulmonary embolism, or cardiac arrest. Complete sudden disappearance of the capnography waveform usually indicates circuit disconnection, obstruction of sampling tubing, obstruction of the airway, or extubation.

Invasive blood pressure monitoring is rarely necessary during laparoscopic procedures. It is, however, very helpful in patients with preexisting severe myocardial or valvular dysfunction or respiratory pathology. It helps with diagnosis and management of significant physiologic disturbances. It also is indicated in extremely obese patients in whom noninvasive monitoring of blood pressure may not be possible after positioning for laparoscopy, for example, with both arms tucked in. Transesophageal echocardiography is valuable for emergency diagnosis of different causes of severe hemodynamic instability, such as hypovolemia, myocardial ischemia, ventricular dysfunction, venous gas embolism, or pulmonary embolism.

Risk Assessment

There are few conditions that may be considered an absolute contraindication to laparoscopy because the risk to the patient is prohibitive or because laparoscopy is technically not feasible. Relative contraindications are more common, including conditions in which laparoscopy may be technically challenging and risky, or undesirable because of physiologic limitations posed by the patient’s comorbidities.

Pneumoperitoneum may lead to cardiac arrest in a patient with preexisting severe hemodynamic compromise, for example, shock, severe aortic stenosis, advanced heart failure, or pericardial effusion. Severe restrictive pulmonary disease, such as extreme scoliosis or previous pneumonectomy, or severe interstitial lung disease with diffusion defects, should also preclude consideration of the laparoscopic technique. In those patients, atelectasis and increased intrapulmonary shunting with pneumoperitoneum may lead to life-threatening hypoxemia. In addition, restricted lung volume does not allow hyperventilation to compensate for CO ₂ absorption during pneumoperitoneum. Extreme hypercapnia may result, leading to postoperative ventilatory failure and the inability to extubate the patient. Forced expiratory volume less than 70% and diffusion capacity less than 80% are predictive of more severe hypercapnia during laparoscopy. Moreover, hypoxia and hypercapnia will exacerbate pulmonary hypertension and right ventricular dysfunction, present in many patients with chronic restrictive or interstitial pulmonary disease. Patients with bullous emphysema or severe obstructive pulmonary disease are at increased risk of barotrauma and pneumothorax during laparoscopy.

Laparoscopy may not be feasible in patients with severely increased intraabdominal pressure—caused, for example, by an extensive, space-occupying tumor, abdominal compartment syndrome, or massive ascites. Other technical challenges to laparoscopy include pregnancy, bowel distention, coagulopathy, abdominal wall infection, and previous extensive abdominal surgery.

Pneumoperitoneum and Trendelenburg positioning are relatively contraindicated in conditions with increased intracranial pressure (brain tumor, hydrocephalus, ventriculoperitoneal shunt) and extreme obesity. Abdominal insufflation, especially in conjunction with the reverse Trendelenburg position, will be poorly tolerated by patients with uncorrected hypovolemia, congestive heart failure, or aortic stenosis. Coexisting coronary artery disease places those patients at an increased risk for intraoperative coronary events. Patients with cerebrovascular disease including carotid or vertebral artery stenosis are at risk for perioperative ischemic stroke during protracted hypotensive episodes.

Major complications of laparoscopic surgery are predominantly due to cardiac events and vascular injury. Mortality rate with laparoscopy is estimated at 0.13%. Cardiac complications account for 25% of laparoscopy-related deaths.

Implications

Laparoscopy has become the gold standard for several surgical procedures (e.g., cholecystectomy or gastric bypass). Laparoscopic surgery is commonly performed in outpatient surgical facilities. Robotically assisted laparoscopic surgical technique, since its introduction in 1999, has gained popularity as a method of choice for several urologic and gynecologic procedures. Owing to the popularity and convenience of laparoscopic approach and a growing collective surgical experience with the technique, some formerly “absolute” contraindications to laparoscopy are no longer considered an obstacle to its use. Consequently, patients at an increased risk for complications inherent in laparoscopic surgery have become a common challenge in contemporary anesthesia practice. The anesthesiologist therefore must be prepared to properly select, screen, and counsel patients considering a laparoscopic procedure. The anesthesiologist and surgeon must be thoroughly familiar with the profound perturbations of normal physiology that take place during laparoscopy and be able to diagnose and manage any complications resulting from these changes.