Complications of Minimal Access Surgery
Introduction
Initial development of “Minimal Access Surgery” began in the animal lab and was later studied in select academic centers. It was imported to the community hospitals only when its benefits and safety were established. The development of laparoscopic cholecystectomy was not designed to enhance the safety of the procedure, but rather to reduce the discomfort associated with the surgical incision. The fierce economical competition in medicine fueled by the managed care movement, led to the rapid adoption of laparoscopic surgery among surgeons and gynecologist in community hospitals who were not formally trained in this technique and acquired their knowledge by subscribing to short courses.
Low complication rates were reported by centers specializing in laparoscopic surgery, mostly in academic centers. These centers were able to reduce the complication rate to minimum by developing proficiency in this surgery. Regrettably many inexperienced surgeons perform this technique with insufficient training and are responsible for the majority of complications seen during the performance of laparoscopic surgery.
Physicians who performed less than 100 such procedures reported 14.7 complications per 1000 patients. In contrast, experienced surgeon reported a complication rate of only 3.8 complications per 1000 procedures. The Southern Surgeons Club Survey reported that the incidence of bile duct injury was 2.2 percent when the surgeon had previously performed less than 13 procedures. As surgeons gained experience the incidence of bile duct injury dropped to 0.1 percent afterward.
Anesthetic and Medical Complications in Laparoscopy
Although all types of anesthesia involve some risk, major side effects and complications from anesthesia in laparoscopy are uncommon. Anesthetic complications include those that are more common in association with laparoscopic surgery as well as those that can occur in any procedure requiring general anesthetics. One-third of the deaths associated, with minor laparoscopic procedures such as sterilization or diagnostic laparoscopy are secondary to complication of anesthesia.
Among the potential complications of all general anesthetics are:
• Hypoventilation
• Esophageal intubation
• Gastroesophageal reflux
• Bronchospasm
• Hypotension
• Narcotic overdose
• Cardiac arrhythmias
• Cardiac arrest.
Laparoscopy results in multiple postoperative benefits including fewer traumas, less pain, less pulmonary dysfunction quicker recovery and shorter hospital stay. These advantages are regularly emphasized and explained. With increasing success of laparoscopy, it is now proposed for many surgical procedures. Intraoperative cardiorespiratory changes occur during pneumoperitoneum PaCO2 increases due to CO2 absorption form peritoneal cavity. Laparoscopy poses a number of inherent features that can enhance some of these risks. For example, the Trendelenburg’s position, in combination with the increased intraperitoneal pressure provided by pneumoperitoneum by CO2, exerts greater pressure on the diaphragm, potentiating hypoventilation, resulting hypercarbia, and metabolic acidosis. This position, combined with anesthetic agents that act as muscle relaxant opens the esophageal sphincter, facilitates regurgitation of gastric content, which, in turn, often leads to aspiration and its attendant complications of bronchospasm, pneumonitis, and pneumonia. Intraoperative aspiration pneumonia is very common in laparoscopy but postoperative pneumonia is common after open surgery.
Various parameters of cardiopulmonary function associated with CO2 insufflation include reduced PaO2, O2 saturation, tidal volume and minute ventilation, as well as an increased respiratory rate. The use of intraperitoneal CO2 as a distention medium is associated with an increase in PaCO2 and a decrease in pH. Increased abdominal pressure and elevation of the diaphragm may be associated with basilar atelectasis, which can result into right-to-left shunt and a ventilation-perfusion mismatch.
Although during laparoscopy the patient’s anesthetic care is in the hands of the anesthesiologist, it is important for the laparoscopic surgeon to understand the prevention and management of anesthetic complications by proper knowledge of risk involved with pneumoperitoneum.
Carbon Dioxide Embolism
Several case reports and experimental data suggest that the first finding during a carbon dioxide embolism may be a rapid increase in end-tidal carbon dioxide tension as some of the carbon dioxide injected into the vascular system is excreted into the lungs. As more gas is injected a vapor lock is formed in portions of the lungs. Areas of the lung are ventilated but not perfused (i.e. become dead space), and the end-tidal carbon dioxide rapidly falls. In contrast, during an air embolism the end-tidal carbon dioxide tension falls immediately. Other findings of a massive carbon dioxide embolism include a harsh, mill wheel murmur, a marked decrease in blood pressure and a decrease in hemoglobin- oxygen saturation. In minimal access surgery the use of CO2 was started just to minimize the risk of CO2 embolism. Carbon dioxide is the most widely used peritoneal distension medium. Part of the reason for this selection is the ready absorption of CO2 in blood. It is 20 times more absorbable than room air; consequently, the vast majority of frequent microemboli that do occur are absorbed, usually by the splanchnic vascular system, quickly and without any incident. However, if large amounts of CO2 gain access to the central venous circulation, if there is peripheral vasoconstriction, or if the splanchnic blood flow is decreased by excessively high intraperitoneal pressure, severe cardiorespiratory compromise may result. The reported incidence of death due to CO2 embolism is not clearly and authentically mentioned in any of the published article but it is assumed to be 1:10,000.
Diagnosis of CO2 Embolism
Carbon dioxide embolism is difficult to diagnose clinically. Among the presenting signs of CO2 embolus are sudden, otherwise unexplained hypotension, cardiac arrhythmia, cyanosis and the development of the classical “mill-wheel” or “water-wheel” heart murmur. The end tidal CO 2 may increase and findings consistent with pulmonary edema may manifest. Accelerating pulmonary hypertension may also occur, resulting in right- sided heart failure.
Prevention of CO2 Embolism
Because gas embolism may occur as a result of direct intravascular injection via an insufflation needle, the surgeon should ensure that blood is not emanating from the needle prior to the initiation of insufflation. Gynecologic surgeons can uniformly reduce the risk of CO2 embolus by operating in an environment where the intraperitoneal pressure is maintained at less than 20 mm Hg. In most instances, excepting the initial placement of trocar in an insufflated peritoneum, the surgeon should be able to function comfortably with the intraperitoneal pressure between 8 and 12 mm Hg, maximum 15 mm Hg. Such pressures may also provide protection from many of the other adverse cardiopulmonary events. The risk of CO2 embolus is also reduced by the meticulous maintenance of hemostasis, and avoiding open venous channels which is the portal of entry for gas into the systemic circulation. Another option in high- risk patient is the use of “ gasless” or “ apneumic” laparoscopy, where extra or intraperitoneal abdominal lifting mechanisms are used to create a working space for the laparoscopic surgeon. However, limitations of these devices have, to date, precluded their wide acceptance by most of the surgeons.
The anesthesiologist should continuously monitor the patient’s skin colors, blood pressure, heart sounds, electrocardiogram, and end-tidal CO2 so that the signs of CO2 embolus are recognized early and can be managed.
Management of CO2 Embolism
If a carbon dioxide embolism should occur:
• The patient should receive on 100 percent oxygen.
• Insufflation should be stopped and the abdomen decompressed.
• The patient should be placed with the right side elevated in the Trendelenburg’s position to avoid further entrapment of carbon dioxide in the pulmonary vasculature.
• A central venous catheter, if placed rapidly, may allow aspiration of carbon dioxide.
• Full inotropic support should be instituted.
Cardiopulmonary bypass may be required to evacuate the gas lock and help remove the carbon dioxide.
If CO2 embolus is suspected or diagnosed, the operating room team must act quickly. The surgeon must evacuate CO2 from the peritoneal cavity and should place the patient in the Durant, or left lateral decubitus position, with the head below the level of the right atrium. A large bore central venous line should be immediately established to allow aspiration of gas from the heart. Because the findings are nonspecific, other causes of cardiovascular collapse should be considered.
Periodically gases other than carbon dioxide are investigated for use for laparoscopy. Argon, air, helium and nitrous oxide have all been used in an attempt to eliminate the problems associated with hypercarbia and peritoneal irritation seen with carbon dioxide. The lack of solubility of air, helium, and argon effectively prevents hypercarbia that occurs with insufflation with carbon dioxide, but increases the lethality many fold if gas embolism occurs. Deaths from argon gas embolism, when the argon beam coagulator has been used during laparoscopy, suggests that this concern is real. Nitrous oxide has solubility similar to that of carbon dioxide, but unfortunately it can support combustion. Explosions when electrocautery was used following insufflation with nitrous oxide have occurred. An intra- abdominal fire when nitrous oxide was intended to be used for insufflation has also been reported.
Cardiovascular Complications
Laparoscopic surgery requires the insufflation of CO2 into the abdominal cavity. Complications associated with CO2 insufflation include:
• Escape of CO2 into the heart or pleural cavity.
• Effects of the resultant increased intra-abdominal pressure on cardiac, renal and liver physiology.
• Effects of the absorbed CO2 on cardiorespiratory function.
The fatal complication of CO2 embolization to the heart and lung were discussed earlier. CO2 is insufflated under 12-15 mm Hg pressure to elevate the abdominal wall and allow the camera the necessary distance to the organ operated on. Depending on the intra-abdominal pressure used and the position the patient is placed—head up or head down—several potential harmful physiologic derangements may occur.
Cardiac arrhythmias occur relatively frequently during the performance of laparoscopic surgery and are related to a number of factors, the most significant of which is hypercarbia and the resulting acidemia. Early reports of laparoscopy associated arrhythmia were in association with spontaneous respiration. Consequently, most anesthesiologists have adopted the universal practice of mechanical ventilation during laparoscopic surgery. There are also a number of pharmacological considerations that lead the anesthesiologist to select agents that limit the risk of cardiac arrhythmia. The surgeon may aid in reducing the incidence of hypercarbia by operating with intraperitoneal pressures that are less than 15 mm Hg.
The use of an alternate intraperitoneal gas is another method by which the risk of cardiac arrhythmia may be reduced. However, while nitrous oxide is associated with a decreased incidence of arrhythmia, it increases the severity of shoulder tip pain, and, more importantly, is insoluble in blood. External lifting systems (apneumic laparoscopy) are another option that can provide protection against cardiac arrhythmia.
Hypotension can also occur secondary to excessively increased intraperitoneal pressure resulting in decreased venous return, and resulting decreased cardiac output. This undesirable result may be potentiated if the patient is volume depleted. Hypotension secondary to cardiac arrhythmias may also be a consequence of vagal discharge in response to increased intraperitoneal pressure. All of these side effects will be more dangerous for the patient with pre-existing cardiovascular compromise.
Gastric Reflux During Laparoscopy
Patients undergoing laparoscopy are usually considered at high risk of acid aspiration syndrome due to gastric regurgitation which might occur due to the rise in intragastric pressure consequent to the increased IAP. However, during pneumoperitoneum, the lower esophageal sphincter tone far exceeds the intragastric pressure and the raised barrier pressure limits the incidence of regurgitation.
Many study aimed to evaluate whether or not the use of intermittent positive pressure ventilation via the laryngeal mask airway is associated with a higher risk of gastroesophageal reflux when compared with intermittent positive pressure ventilation via a tracheal tube in patients undergoing day case gynecological laparoscopy in the head- down position.
Generally gastric regurgitation and aspiration are complications potentiated by laparoscopic surgery. Some patients are at increased risk, including those with obesity, gastroparesis, hiatal hernia or any type of gastric outlet obstruction. In such patients, it is important to quickly secure the airway with a cuffed endotracheal tube and to routinely decompress the stomach with a nasogastric or orogastric tube. The surgeon can contribute to aspiration prophylaxis by operating at the lowest necessary intraperitoneal pressure. Patients should be taken out of the Trendelenburg’s position prior to being extubated. The adverse effects of aspiration may be minimized with the routine preoperative administration of metoclopramide, H 2 blockers, and nonparticulate antacids.
Extraperitoneal Gas
During laparoscopic surgery a number of the complications associated with pneumoperitoneum or its achievement are described in the vascular, gastroenterologic, urologic, and anesthetic sections. However, the problem of extraperitoneal placement or extravasation of gas has not been considered. In some instances, this complication occurs as a result of deficient technique (incorrect placement of insufflation needles; excessive intraperitoneal pressure); while in others the extravasation is related to gas tracking around the ports or along the dissection planes themselves.
Subcutaneous emphysema may occur if the tip of the Veress needle does not penetrate the peritoneal cavity prior to insufflation of gas. The gas may accumulate in the subcutaneous tissue or between the fascia and the peritoneum. Extraperitoneal insufflation, which is associated with higher levels of CO2 absorption than intraperitoneal insufflation, is reflected by a sudden rise in the EtCO2, excessive changes in airway pressure and respiratory acidosis.
Subcutaneous emphysema most commonly results from preperitoneal placement of an insufflation needle or leakage of CO2 around the cannula sites, the latter frequently because of excessive intraperitoneal pressure. The condition is usually mild and limited to the abdominal wall. However, subcutaneous emphysema can become extensive, involving the extremities, the neck, and the mediastinum. Another relatively common location for emphysema is the omentum or mesentery, a circumstance that the surgeon may mistake for preperitoneal insufflation.
Diagnosis
Usually the diagnosis will not be a surprise, for the surgeon will have had difficulty in positioning the primary cannula within the peritoneal cavity. Subcutaneous emphysema may be readily identified by the palpation of crepitus, usually in the abdominal wall. In some instances, it can extend along contiguous fascial planes to the neck, where it can be visualized directly. Such a finding may reflect the development of mediastinal emphysema. If mediastinal emphysema is severe, or if pneumothorax is developing, the anesthesiologist may report difficulty in maintaining a normal pCO2, a feature that may indicate impending cardiovascular collapse.
Prevention
The risk of subcutaneous emphysema during laparoscopic surgery is reduced by proper positioning of an insufflation needle. Prior to insertion, it is important to check the insufflation needle for proper function and patency and to establish the baseline flow pressure by attaching it to the insufflation apparatus. The best position for insertion is at the base of the umbilicus, where the abdominal wall is the thinnest. The angle of insertion varies from 45° to near 90°, depending upon the patient’s weight, the previous abdominal surgery and type of anesthesia as described in the section on prevention of vascular injuries. The insertion action should be smooth and firm until the surgeon, observing and listening to the device passing through the layers-two (fascia and peritoneum) in the umbilicus and three (two layers of fascia; one peritoneum) in the left upper quadrant feels that placement is intraperitoneal.
No one test is absolutely reliable at predicting intraperitoneal placement. Instead, a number of tests should be used. Of course, aspiration of the insufflation needle should precede all other evaluations. Two tests depend upon the preinflation intraperitoneal pressure. If a drop of water is placed on the open end of the insufflation needle, it should be drawn into the low-pressure intraperitoneal environment of the peritoneal cavity. Although some disagree, the elevation of the anterior abdominal wall is a reasonable way of creating a negative intraperitoneal pressure. Perhaps a more quantitative way of demonstrating the same principle is to attach the tubing to the needle after insertion but prior to initiating the flow of gas. Elevation of the abdominal wall should result in creation of a low or negative intraperitoneal pressure (1 to 4 mm Hg). Insufflation should be initiated at a low flow rate of about 1 liter per minute until the surgeon has confidence that proper placement has been achieved. Loss of liver dullness should occur when about 500 ml of gas has entered the peritoneal cavity. The measured intraperitoneal pressure should be below 10 mm Hg but up to14 mm Hg if the patient is obese. Abdominal distension should be symmetrical. If, at any time, the surgeon feels that, the needle is not located intraperitoneally, it should be withdrawn and reinserted. Once the peritoneal cavity has been insufflated with an adequate volume of gas, the primary trocar is introduced. The laparoscope is introduced, and, if the cannula is satisfactorily located the tubing is attached to the appropriate port.
The risk of subcutaneous emphysema may be reduced by maintaining a low intraperitoneal pressure following the placement of the desired cannulas Operate below 15 mm Hg and usually work at about 10 mm Hg. Although primary blind insertion of sharp trocar has been demonstrated to be as safe as secondary insertion following pneumoinsufflation, the relative incidence of subcutaneous emphysema is unknown.
Management
Subcutaneous emphysema often presents a management dilemma. Rarely, subcutaneous emphysema has pathophysiologic consequences. More often, it is extremely uncomfortable for the patient, and is often disfiguring and alarming for patients and family. When subcutaneous emphysema is severe, physicians may feel compelled to treat it, but the currently described techniques are often invasive or ineffective.
If the surgeon finds that the insufflation has occurred extraperitoneally, there exist a number of management options. While removing the laparoscope and repeating the insufflation is possible, it may be made more difficult because of the new configuration of the anterior peritoneum. Open laparoscopy or the use of an alternate sites such as the left upper quadrant should be considered. One attractive approach is to leave the laparoscope in the expanded preperitoneal space while the insufflation needle is reinserted through the peritoneal membrane, caudal to the tip of the laparoscope under direct vision.
For mild cases of subcutaneous emphysema, no specific intra-or postoperative therapy is required, as the findings, in at least mild cases, quickly resolves following evacuation of the pneumoperitoneum. When the extravasation extends to involve the neck, it is usually preferable to terminate the procedure, as pneumomediastinum, pneumothorax, hypercarbia and cardiovascular collapse may result. Following the end of the procedure it is prudent to obtain a chest X-ray. The patient should be managed expectantly unless a tension pneumothorax results, when immediate evacuation must be performed, using a chest tube or a wide bore needle (14-16 gauge) inserted in the second intercostal space in midclavicular line.
Introduction
Initial development of “Minimal Access Surgery” began in the animal lab and was later studied in select academic centers. It was imported to the community hospitals only when its benefits and safety were established. The development of laparoscopic cholecystectomy was not designed to enhance the safety of the procedure, but rather to reduce the discomfort associated with the surgical incision. The fierce economical competition in medicine fueled by the managed care movement, led to the rapid adoption of laparoscopic surgery among surgeons and gynecologist in community hospitals who were not formally trained in this technique and acquired their knowledge by subscribing to short courses.
Low complication rates were reported by centers specializing in laparoscopic surgery, mostly in academic centers. These centers were able to reduce the complication rate to minimum by developing proficiency in this surgery. Regrettably many inexperienced surgeons perform this technique with insufficient training and are responsible for the majority of complications seen during the performance of laparoscopic surgery.
Physicians who performed less than 100 such procedures reported 14.7 complications per 1000 patients. In contrast, experienced surgeon reported a complication rate of only 3.8 complications per 1000 procedures. The Southern Surgeons Club Survey reported that the incidence of bile duct injury was 2.2 percent when the surgeon had previously performed less than 13 procedures. As surgeons gained experience the incidence of bile duct injury dropped to 0.1 percent afterward.
Anesthetic and Medical Complications in Laparoscopy
Although all types of anesthesia involve some risk, major side effects and complications from anesthesia in laparoscopy are uncommon. Anesthetic complications include those that are more common in association with laparoscopic surgery as well as those that can occur in any procedure requiring general anesthetics. One-third of the deaths associated, with minor laparoscopic procedures such as sterilization or diagnostic laparoscopy are secondary to complication of anesthesia.
Among the potential complications of all general anesthetics are:
• Hypoventilation
• Esophageal intubation
• Gastroesophageal reflux
• Bronchospasm
• Hypotension
• Narcotic overdose
• Cardiac arrhythmias
• Cardiac arrest.
Laparoscopy results in multiple postoperative benefits including fewer traumas, less pain, less pulmonary dysfunction quicker recovery and shorter hospital stay. These advantages are regularly emphasized and explained. With increasing success of laparoscopy, it is now proposed for many surgical procedures. Intraoperative cardiorespiratory changes occur during pneumoperitoneum PaCO2 increases due to CO2 absorption form peritoneal cavity. Laparoscopy poses a number of inherent features that can enhance some of these risks. For example, the Trendelenburg’s position, in combination with the increased intraperitoneal pressure provided by pneumoperitoneum by CO2, exerts greater pressure on the diaphragm, potentiating hypoventilation, resulting hypercarbia, and metabolic acidosis. This position, combined with anesthetic agents that act as muscle relaxant opens the esophageal sphincter, facilitates regurgitation of gastric content, which, in turn, often leads to aspiration and its attendant complications of bronchospasm, pneumonitis, and pneumonia. Intraoperative aspiration pneumonia is very common in laparoscopy but postoperative pneumonia is common after open surgery.
Various parameters of cardiopulmonary function associated with CO2 insufflation include reduced PaO2, O2 saturation, tidal volume and minute ventilation, as well as an increased respiratory rate. The use of intraperitoneal CO2 as a distention medium is associated with an increase in PaCO2 and a decrease in pH. Increased abdominal pressure and elevation of the diaphragm may be associated with basilar atelectasis, which can result into right-to-left shunt and a ventilation-perfusion mismatch.
Although during laparoscopy the patient’s anesthetic care is in the hands of the anesthesiologist, it is important for the laparoscopic surgeon to understand the prevention and management of anesthetic complications by proper knowledge of risk involved with pneumoperitoneum.
Carbon Dioxide Embolism
Several case reports and experimental data suggest that the first finding during a carbon dioxide embolism may be a rapid increase in end-tidal carbon dioxide tension as some of the carbon dioxide injected into the vascular system is excreted into the lungs. As more gas is injected a vapor lock is formed in portions of the lungs. Areas of the lung are ventilated but not perfused (i.e. become dead space), and the end-tidal carbon dioxide rapidly falls. In contrast, during an air embolism the end-tidal carbon dioxide tension falls immediately. Other findings of a massive carbon dioxide embolism include a harsh, mill wheel murmur, a marked decrease in blood pressure and a decrease in hemoglobin- oxygen saturation. In minimal access surgery the use of CO2 was started just to minimize the risk of CO2 embolism. Carbon dioxide is the most widely used peritoneal distension medium. Part of the reason for this selection is the ready absorption of CO2 in blood. It is 20 times more absorbable than room air; consequently, the vast majority of frequent microemboli that do occur are absorbed, usually by the splanchnic vascular system, quickly and without any incident. However, if large amounts of CO2 gain access to the central venous circulation, if there is peripheral vasoconstriction, or if the splanchnic blood flow is decreased by excessively high intraperitoneal pressure, severe cardiorespiratory compromise may result. The reported incidence of death due to CO2 embolism is not clearly and authentically mentioned in any of the published article but it is assumed to be 1:10,000.
Diagnosis of CO2 Embolism
Carbon dioxide embolism is difficult to diagnose clinically. Among the presenting signs of CO2 embolus are sudden, otherwise unexplained hypotension, cardiac arrhythmia, cyanosis and the development of the classical “mill-wheel” or “water-wheel” heart murmur. The end tidal CO 2 may increase and findings consistent with pulmonary edema may manifest. Accelerating pulmonary hypertension may also occur, resulting in right- sided heart failure.
Prevention of CO2 Embolism
Because gas embolism may occur as a result of direct intravascular injection via an insufflation needle, the surgeon should ensure that blood is not emanating from the needle prior to the initiation of insufflation. Gynecologic surgeons can uniformly reduce the risk of CO2 embolus by operating in an environment where the intraperitoneal pressure is maintained at less than 20 mm Hg. In most instances, excepting the initial placement of trocar in an insufflated peritoneum, the surgeon should be able to function comfortably with the intraperitoneal pressure between 8 and 12 mm Hg, maximum 15 mm Hg. Such pressures may also provide protection from many of the other adverse cardiopulmonary events. The risk of CO2 embolus is also reduced by the meticulous maintenance of hemostasis, and avoiding open venous channels which is the portal of entry for gas into the systemic circulation. Another option in high- risk patient is the use of “ gasless” or “ apneumic” laparoscopy, where extra or intraperitoneal abdominal lifting mechanisms are used to create a working space for the laparoscopic surgeon. However, limitations of these devices have, to date, precluded their wide acceptance by most of the surgeons.
The anesthesiologist should continuously monitor the patient’s skin colors, blood pressure, heart sounds, electrocardiogram, and end-tidal CO2 so that the signs of CO2 embolus are recognized early and can be managed.
Management of CO2 Embolism
If a carbon dioxide embolism should occur:
• The patient should receive on 100 percent oxygen.
• Insufflation should be stopped and the abdomen decompressed.
• The patient should be placed with the right side elevated in the Trendelenburg’s position to avoid further entrapment of carbon dioxide in the pulmonary vasculature.
• A central venous catheter, if placed rapidly, may allow aspiration of carbon dioxide.
• Full inotropic support should be instituted.
Cardiopulmonary bypass may be required to evacuate the gas lock and help remove the carbon dioxide.
If CO2 embolus is suspected or diagnosed, the operating room team must act quickly. The surgeon must evacuate CO2 from the peritoneal cavity and should place the patient in the Durant, or left lateral decubitus position, with the head below the level of the right atrium. A large bore central venous line should be immediately established to allow aspiration of gas from the heart. Because the findings are nonspecific, other causes of cardiovascular collapse should be considered.
Periodically gases other than carbon dioxide are investigated for use for laparoscopy. Argon, air, helium and nitrous oxide have all been used in an attempt to eliminate the problems associated with hypercarbia and peritoneal irritation seen with carbon dioxide. The lack of solubility of air, helium, and argon effectively prevents hypercarbia that occurs with insufflation with carbon dioxide, but increases the lethality many fold if gas embolism occurs. Deaths from argon gas embolism, when the argon beam coagulator has been used during laparoscopy, suggests that this concern is real. Nitrous oxide has solubility similar to that of carbon dioxide, but unfortunately it can support combustion. Explosions when electrocautery was used following insufflation with nitrous oxide have occurred. An intra- abdominal fire when nitrous oxide was intended to be used for insufflation has also been reported.
Cardiovascular Complications
Laparoscopic surgery requires the insufflation of CO2 into the abdominal cavity. Complications associated with CO2 insufflation include:
• Escape of CO2 into the heart or pleural cavity.
• Effects of the resultant increased intra-abdominal pressure on cardiac, renal and liver physiology.
• Effects of the absorbed CO2 on cardiorespiratory function.
The fatal complication of CO2 embolization to the heart and lung were discussed earlier. CO2 is insufflated under 12-15 mm Hg pressure to elevate the abdominal wall and allow the camera the necessary distance to the organ operated on. Depending on the intra-abdominal pressure used and the position the patient is placed—head up or head down—several potential harmful physiologic derangements may occur.
Cardiac arrhythmias occur relatively frequently during the performance of laparoscopic surgery and are related to a number of factors, the most significant of which is hypercarbia and the resulting acidemia. Early reports of laparoscopy associated arrhythmia were in association with spontaneous respiration. Consequently, most anesthesiologists have adopted the universal practice of mechanical ventilation during laparoscopic surgery. There are also a number of pharmacological considerations that lead the anesthesiologist to select agents that limit the risk of cardiac arrhythmia. The surgeon may aid in reducing the incidence of hypercarbia by operating with intraperitoneal pressures that are less than 15 mm Hg.
The use of an alternate intraperitoneal gas is another method by which the risk of cardiac arrhythmia may be reduced. However, while nitrous oxide is associated with a decreased incidence of arrhythmia, it increases the severity of shoulder tip pain, and, more importantly, is insoluble in blood. External lifting systems (apneumic laparoscopy) are another option that can provide protection against cardiac arrhythmia.
Hypotension can also occur secondary to excessively increased intraperitoneal pressure resulting in decreased venous return, and resulting decreased cardiac output. This undesirable result may be potentiated if the patient is volume depleted. Hypotension secondary to cardiac arrhythmias may also be a consequence of vagal discharge in response to increased intraperitoneal pressure. All of these side effects will be more dangerous for the patient with pre-existing cardiovascular compromise.
Gastric Reflux During Laparoscopy
Patients undergoing laparoscopy are usually considered at high risk of acid aspiration syndrome due to gastric regurgitation which might occur due to the rise in intragastric pressure consequent to the increased IAP. However, during pneumoperitoneum, the lower esophageal sphincter tone far exceeds the intragastric pressure and the raised barrier pressure limits the incidence of regurgitation.
Many study aimed to evaluate whether or not the use of intermittent positive pressure ventilation via the laryngeal mask airway is associated with a higher risk of gastroesophageal reflux when compared with intermittent positive pressure ventilation via a tracheal tube in patients undergoing day case gynecological laparoscopy in the head- down position.
Generally gastric regurgitation and aspiration are complications potentiated by laparoscopic surgery. Some patients are at increased risk, including those with obesity, gastroparesis, hiatal hernia or any type of gastric outlet obstruction. In such patients, it is important to quickly secure the airway with a cuffed endotracheal tube and to routinely decompress the stomach with a nasogastric or orogastric tube. The surgeon can contribute to aspiration prophylaxis by operating at the lowest necessary intraperitoneal pressure. Patients should be taken out of the Trendelenburg’s position prior to being extubated. The adverse effects of aspiration may be minimized with the routine preoperative administration of metoclopramide, H 2 blockers, and nonparticulate antacids.
Extraperitoneal Gas
During laparoscopic surgery a number of the complications associated with pneumoperitoneum or its achievement are described in the vascular, gastroenterologic, urologic, and anesthetic sections. However, the problem of extraperitoneal placement or extravasation of gas has not been considered. In some instances, this complication occurs as a result of deficient technique (incorrect placement of insufflation needles; excessive intraperitoneal pressure); while in others the extravasation is related to gas tracking around the ports or along the dissection planes themselves.
Subcutaneous emphysema may occur if the tip of the Veress needle does not penetrate the peritoneal cavity prior to insufflation of gas. The gas may accumulate in the subcutaneous tissue or between the fascia and the peritoneum. Extraperitoneal insufflation, which is associated with higher levels of CO2 absorption than intraperitoneal insufflation, is reflected by a sudden rise in the EtCO2, excessive changes in airway pressure and respiratory acidosis.
Subcutaneous emphysema most commonly results from preperitoneal placement of an insufflation needle or leakage of CO2 around the cannula sites, the latter frequently because of excessive intraperitoneal pressure. The condition is usually mild and limited to the abdominal wall. However, subcutaneous emphysema can become extensive, involving the extremities, the neck, and the mediastinum. Another relatively common location for emphysema is the omentum or mesentery, a circumstance that the surgeon may mistake for preperitoneal insufflation.
Diagnosis
Usually the diagnosis will not be a surprise, for the surgeon will have had difficulty in positioning the primary cannula within the peritoneal cavity. Subcutaneous emphysema may be readily identified by the palpation of crepitus, usually in the abdominal wall. In some instances, it can extend along contiguous fascial planes to the neck, where it can be visualized directly. Such a finding may reflect the development of mediastinal emphysema. If mediastinal emphysema is severe, or if pneumothorax is developing, the anesthesiologist may report difficulty in maintaining a normal pCO2, a feature that may indicate impending cardiovascular collapse.
Prevention
The risk of subcutaneous emphysema during laparoscopic surgery is reduced by proper positioning of an insufflation needle. Prior to insertion, it is important to check the insufflation needle for proper function and patency and to establish the baseline flow pressure by attaching it to the insufflation apparatus. The best position for insertion is at the base of the umbilicus, where the abdominal wall is the thinnest. The angle of insertion varies from 45° to near 90°, depending upon the patient’s weight, the previous abdominal surgery and type of anesthesia as described in the section on prevention of vascular injuries. The insertion action should be smooth and firm until the surgeon, observing and listening to the device passing through the layers-two (fascia and peritoneum) in the umbilicus and three (two layers of fascia; one peritoneum) in the left upper quadrant feels that placement is intraperitoneal.
No one test is absolutely reliable at predicting intraperitoneal placement. Instead, a number of tests should be used. Of course, aspiration of the insufflation needle should precede all other evaluations. Two tests depend upon the preinflation intraperitoneal pressure. If a drop of water is placed on the open end of the insufflation needle, it should be drawn into the low-pressure intraperitoneal environment of the peritoneal cavity. Although some disagree, the elevation of the anterior abdominal wall is a reasonable way of creating a negative intraperitoneal pressure. Perhaps a more quantitative way of demonstrating the same principle is to attach the tubing to the needle after insertion but prior to initiating the flow of gas. Elevation of the abdominal wall should result in creation of a low or negative intraperitoneal pressure (1 to 4 mm Hg). Insufflation should be initiated at a low flow rate of about 1 liter per minute until the surgeon has confidence that proper placement has been achieved. Loss of liver dullness should occur when about 500 ml of gas has entered the peritoneal cavity. The measured intraperitoneal pressure should be below 10 mm Hg but up to14 mm Hg if the patient is obese. Abdominal distension should be symmetrical. If, at any time, the surgeon feels that, the needle is not located intraperitoneally, it should be withdrawn and reinserted. Once the peritoneal cavity has been insufflated with an adequate volume of gas, the primary trocar is introduced. The laparoscope is introduced, and, if the cannula is satisfactorily located the tubing is attached to the appropriate port.
The risk of subcutaneous emphysema may be reduced by maintaining a low intraperitoneal pressure following the placement of the desired cannulas Operate below 15 mm Hg and usually work at about 10 mm Hg. Although primary blind insertion of sharp trocar has been demonstrated to be as safe as secondary insertion following pneumoinsufflation, the relative incidence of subcutaneous emphysema is unknown.
Management
Subcutaneous emphysema often presents a management dilemma. Rarely, subcutaneous emphysema has pathophysiologic consequences. More often, it is extremely uncomfortable for the patient, and is often disfiguring and alarming for patients and family. When subcutaneous emphysema is severe, physicians may feel compelled to treat it, but the currently described techniques are often invasive or ineffective.
If the surgeon finds that the insufflation has occurred extraperitoneally, there exist a number of management options. While removing the laparoscope and repeating the insufflation is possible, it may be made more difficult because of the new configuration of the anterior peritoneum. Open laparoscopy or the use of an alternate sites such as the left upper quadrant should be considered. One attractive approach is to leave the laparoscope in the expanded preperitoneal space while the insufflation needle is reinserted through the peritoneal membrane, caudal to the tip of the laparoscope under direct vision.
For mild cases of subcutaneous emphysema, no specific intra-or postoperative therapy is required, as the findings, in at least mild cases, quickly resolves following evacuation of the pneumoperitoneum. When the extravasation extends to involve the neck, it is usually preferable to terminate the procedure, as pneumomediastinum, pneumothorax, hypercarbia and cardiovascular collapse may result. Following the end of the procedure it is prudent to obtain a chest X-ray. The patient should be managed expectantly unless a tension pneumothorax results, when immediate evacuation must be performed, using a chest tube or a wide bore needle (14-16 gauge) inserted in the second intercostal space in midclavicular line.
