1 What are the origins of modern laparoscopic surgery?

P. Bozzini developed the first self-contained endoscope in 1805, using candlelight for illumination. The first clinical laparoscopic examination in humans was performed by H. Jacobaeus in 1910. By the 1970s gynecologic laparoscopic surgery was being performed routinely. The first laparoscopic appendectomy was performed by Semm in 1983, and the first laparoscopic cholecystectomy was performed by Muhe in 1985. Since then the concept and techniques have rapidly expanded to include multiple surgical disciplines. Laparoscopic surgery has become the standard of care for some procedures.

2 What are some currently practiced laparoscopic, thoracoscopic, or endoscopic procedures?

General surgery: Multiple procedures involving the appendix, colon, small bowel, gallbladder, bile ducts, stomach, esophagus, liver, spleen, pancreas, and adrenals. In addition, hernia repairs, diagnostic laparoscopy, adhesiolysis, gastric bypass, gastric banding, Nissen fundoplication, and feeding-tube placement can be performed laparoscopically

Gynecologic procedures: Diagnostic procedures for chronic pelvic pain, hysterectomy, tubal ligation, pelvic lymph node dissection, hysteroscopy, myomectomy, oophorectomy, and laser ablation of endometriosis

Thoracoscopic procedure/video-assisted thoracic surgery: Lobectomy, pneumonectomy, wedge resection, drainage of pleural effusions and pleurodesis, evaluation of blunt or pulmonary trauma, resection of solitary pulmonary nodules, tumor staging, repair of esophageal perforations, pleural biopsy, excision of mediastinal masses, transthoracic sympathectomy, splanchnicectomy, pericardiocentesis, pericardiectomy, and esophagectomy

Cardiac surgery: Coronary artery bypass, valve repair

Orthopedics: Joint arthroscopy, including knee, hip, shoulder, wrist, and elbow

Urologic procedures: Laparoscopic nephrectomy/nephroureterectomy, pyeloplasty, orchiopexy, cystoscopy/ureteroscopy, and prostatectomy

Neurosurgery: Ventriculoscopy, microendoscopic diskectomy, interbody fusion, anterior spinal surgery and scoliosis/kyphosis correction, and image-guided techniques to approach masses/tumors easily

Plastic/reconstructive surgery: Breast augmentation, brow lift, face lift, and liposuction techniques

Transplant surgery: Donor nephrectomy

Improvements in scope technology have allowed many procedures to be performed without large surgical incisions, affording the patient rapid recovery of function. However, the focus of this discussion will be the physiologic concerns associated with abdominal laparoscopy since they are of utmost importance to the anesthesiologist.

3 Are there any contraindications for laparoscopic procedures?

Relative contraindications for laparoscopy include increased intracranial pressure, patients with ventriculoperitoneal or peritoneojugular shunts, hypovolemia, congestive heart failure, or severe cardiopulmonary disease and coagulopathy. Morbid obesity, pregnancy, and prior abdominal surgery were previously considered contraindications to laparoscopic surgery; however, with improved surgical techniques, technology, and experience, most patients with these conditions can safely undergo laparoscopic surgery.

4 What are the benefits of laparoscopy when compared with open procedures?

Intraoperative benefits: Decreased stress response with a reduction of acute phase reactants (C-reactive protein and interleukin-6), decreased metabolic response with reduced hyperglycemia and leukocytosis, decreased fluid shifts, better preserved systemic immune function, and avoidance of prolonged exposure and manipulation of abdominal contents.

Postoperative benefits: Less postoperative pain and fewer analgesic requirements, improved pulmonary function (secondary to decreased pain, decreased atelectasis, and earlier ambulation), improved cosmesis because of smaller incisions, fewer wound infections, decreased postoperative ileus, decreased length of hospitalization, and a quicker resumption of normal daily activities.

5 Why has carbon dioxide become the insufflation gas of choice during laparoscopy?

The choice of an insufflating gas for the creation of pneumoperitoneum is influenced by the blood solubility of the gas and its tissue permeability, combustibility, expense, and potential to cause side effects. The ideal gas would be physiologically inert, colorless, and capable of undergoing pulmonary excretion. Although a number of gases have been used (Table 74-1), carbon dioxide (CO₂) has become the gas of choice since it offers the best compromise between potential advantages and disadvantages.

TABLE 74-1 Comparison of Gases for Insufflation

6 How does carbon dioxide insufflation affect PaCO₂?

CO₂ insufflation increases the partial pressure of carbon dioxide (PaCO₂). The degree of increase in PaCO₂ depends on the intra-abdominal pressure, the patient’s age, underlying medical conditions, patient positioning, and the mode of ventilation. In healthy patients the primary mechanism of increased PaCO₂ is absorption via the peritoneum. Increases in intra-abdominal pressure also result in diaphragmatic dysfunction and increased alveolar dead space, leading to ventilatory impairment and subsequent increases in PaCO₂. Spontaneous ventilation under local anesthesia does not result in a rise in PaCO₂; however, other anesthetic techniques and ventilatory modes will result in hypercapnia unless ventilation is adjusted. PaCO₂ rises approximately 5 to 10 minutes after CO₂ insufflation and usually reaches a plateau after 20 to 25 minutes. The gradient between PaCO₂ and end-tidal pressure of CO₂ does not change significantly during insufflation, but it does increase during maintenance of pneumoperitoneum, especially in more compromised patients. The final PaCO₂ levels tend to be significantly higher in patients with cardiopulmonary disease than in healthy patients undergoing similar procedures.

7 How does patient positioning affect hemodynamics and pulmonary function during laparoscopy?

During laparoscopic surgery the patient is positioned to use gravitational displacement of the abdominal contents away from the surgical site to facilitate optimal surgical exposure.

Trendelenburg position: Cardiac output (CO) and central venous pressure (CVP) increase, and patients with intact baroreceptor reflexes typically experience vasodilation and bradycardia. The Trendelenburg position decreases the transmural pressure in the pelvic organs, possibly decreasing blood loss but increasing the risk of gas emboli. Pulmonary effects include impaired diaphragmatic function secondary to the cephalad displacement of abdominal viscera, resulting in decreased functional residual capacity (FRC), total lung capacity, and pulmonary compliance, predisposing the patient to developing atelectasis. Cephalad migration of lungs and carina may result in main stem intubation.

Reverse Trendelenburg position: Preload is decreased, resulting in decreased CO and mean arterial pressure (MAP). Blood pooling in the lower extremities may increase the risk of venous thrombosis and pulmonary emboli. Intraoperative sequential intermittent pneumatic compression of the lower extremities is recommended. Pulmonary function is improved compared to supine or Trendelenburg position secondary to downward positioning of the diaphragm.

8 What is considered a safe increase in intra-abdominal pressure?

The current recommendation for intra-abdominal pressure (IAP) during laparoscopy is less than 15 mm Hg, and most laparoscopic procedures are performed with IAPs in the 12- to 15-mm Hg range. In general IAPs less than 10 mm Hg have minimal physiologic effects. Insufflation pressures above 16 mm Hg result in undesirable physiologic changes (i.e., decreased CO, increased systemic vascular resistance [SVR] and decreased compliance of the lung and chest wall). At pressures greater than 20 mm Hg, renal blood flow (RBF), glomerular filtration rate, and urine output also decline. Insufflation pressures of 30 to 40 mm Hg have significant adverse hemodynamic effects and should be avoided. Many insufflation machines are set to alarm at 15 mm Hg. If the machine alarms when the surgeon is not insufflating with high pressure, the anesthesiologist should consider insufficient abdominal wall relaxation as one possible cause of the high-pressure alarm. Low-pressure pneumoperitoneum (7 mm Hg) and gasless laparoscopy have been advocated as means of decreasing the magnitude of hemodynamic derangement associated with higher IAP.

The observed changes in CO are biphasic: CO initially decreases with onset of CO₂ insufflation; within 5 to 10 minutes CO begins to increase, approaching preinsufflation values. At IAPs greater than 10 mm Hg, venous return decreases, but cardiac filling pressures increase most likely because of increased intrathoracic pressure; therefore with abdominal insufflation the usual methods of measuring CVP or left ventricular end-diastolic pressure are inaccurate and overestimate true filling conditions. Adequate intravascular volume loading will help maintain CO. SVR and MAP also significantly increase during the initial stages of insufflation. Although these changes partially resolve approximately 10 to 15 minutes after insufflation, the changes in cardiac filling pressures and SVR increase left ventricular wall stress. Pulmonary vascular resistance is also increased. In healthy patients left ventricular function appears to be preserved; however, in patients with underlying cardiovascular disease, the changes could be deleterious (Table 74-2).

TABLE 74-2 Hemodynamic Changes During Laparoscopy

CVP, Central venous pressure; IAP, intra-abdominal pressure; MAP, mean arterial pressure; PAOP, pulmonary artery occlusion pressure; SVR, systemic vascular resistance.

9 Describe pulmonary changes associated with pneumoperitoneum

CO₂ insufflation and the resultant increase in intra-abdominal pressure result in cephalad displacement of the diaphragm, reducing FRC and compliance. Trendelenburg position further aggravates these changes. When the FRC is reduced relative to the patient’s closing capacity, hypoxemia may result from atelectasis and intrapulmonary shunting. Positive end-expiratory pressure of 10 during pneumoperitoneum decreases CO and preload. Hypoxemia is uncommon in healthy patients but becomes a concern in obese patients or those with underlying cardiopulmonary disease since it can be difficult to ventilate against the pressure of the pneumoperitoneum adequately in compromised patients (Table 74-3).

TABLE 74-3 Pulmonary Changes Associated with Laparoscopy

10 What effect does the intra-abdominal pressure increase have on perfusion of intra-abdominal organs?

An IAP of 12 to 14 mm Hg decreases RBF, glomerular filtration rate, and urine output. The reduction in RBF is related to the decreased CO and/or compression of the renal vein. Hepatoportal arterial and venous blood flow is gradually decreased with increasing IAP, and elevated liver enzymes have been noted after prolonged laparoscopic cases. Splanchnic microcirculation is decreased.

11 What are the neurohumoral responses associated with laparoscopy?

Plasma concentrations of dopamine, vasopressin, epinephrine, norepinephrine, renin, angiotensin, and cortisol all significantly increase. The increases correspond to the onset of abdominal insufflation. Serum levels of vasopressin and norepinephrine most closely parallel the changes noted in CO, MAP, and SVR. Hypercarbia, the mechanical effects of the pneumoperitoneum, and stimulation of the autonomic nervous system have all been implicated as possible causes of these observed changes. Preoperative α₂-adrenergic agonists (clonidine/dexmedetomidine) have been shown to decrease the stress response.

12 Should nitrous oxide be used as an anesthetic adjuvant during laparoscopy?

There are no clinically significant differences in bowel distention and postoperative nausea and vomiting when nitrous oxide (N₂O)–oxygen was compared to air-oxygen, and no conclusive evidence suggests that N₂O cannot be used during laparoscopy.

13 What anesthetic techniques can be used for minimally invasive surgery?

Local anesthesia with intravenous (IV) sedation, regional techniques, and general anesthesia have all been used with favorable results. The unexpected conversion from a laparoscopic to an open procedure must be considered when choosing an anesthetic technique.

Local anesthetic with IV sedation: Advantages include reduced anesthetic time, quicker recovery time, decreased postoperative nausea and vomiting, earlier recognition of complications, and fewer hemodynamic changes. Success depends on patient motivation, precise surgical technique, and short procedure time. This technique should be avoided in any procedure of long duration that requires multiple trocar sites, steep positioning, and large increases in IAP.

Regional anesthesia: Advantages and disadvantages are similar to those of local anesthesia. However, the high level of sympathetic denervation in concert with abdominal insufflation and positioning extremes could be associated with adverse ventilatory and circulatory changes.

General anesthesia: General anesthesia is the most frequently used technique. Advantages include optimal muscle relaxation, amnesia, ability to position the patient as needed, ability to control ventilation, protection from gastric aspiration, and a quiet surgical field. The laryngeal mask airway (LMA) has been substituted for endotracheal intubation but does not protect against pulmonary aspiration of gastric contents. Controlled ventilation is also difficult with an LMA since peak inspiratory pressures increase with pneumoperitoneum. Urinary bladder and gastric decompression should be performed to decrease the risk of visceral puncture and improve the surgical field.

14 Can laparoscopy be performed on children or pregnant women?

Laparoscopic surgery is now commonly performed in pediatric populations. Children undergo similar physiologic changes and experience similar benefits of laparoscopic procedures as adults. CO₂ absorption in infants may be faster and more profound than in adults because of a greater peritoneal surface area–to–body weight ratio.

Pregnancy was initially considered to be a contraindication to laparoscopic surgery because of concerns regarding decreased uterine blood flow, increased intrauterine pressure, and resultant fetal hypoxia and acidosis. Multiple reports have since determined that laparoscopic surgery is safe in pregnancy and does not result in increased rates of fetal morbidity or mortality. Since fetal acidosis is typically more severe than maternal acidosis, the end-tidal CO₂ concentration should be maintained between 25 and 33 mm Hg. Procedures should be performed in the second trimester if possible. Body positioning should avoid inferior vena cava compression. Abdominal insufflation pressure should be kept as low as possible in pregnant patients.

15 What complications are associated with laparoscopic surgery and carbon dioxide pneumoperitoneum?

Complications are most likely to occur during placement of the trocar through the abdominal wall and CO₂ insufflation.

Intraoperative complications: Major vessel injury, hemorrhage, organ perforation, bladder and ureter injury, burns, cardiac arrhythmias (atrioventricular dissociation, nodal rhythms, bradycardia, and asystole), hypercapnia, hypoxemia, CO₂ subcutaneous emphysema, pneumothorax, gas embolism, endobronchial intubation, increased intracranial pressure, and aspiration are all risks. Other complications are possible, depending on the specific procedure performed.

Postoperative complications: Postoperative nausea and vomiting, pain, shoulder and neck pain secondary to diaphragmatic irritation, deep venous thrombosis, delayed hemorrhage, peritonitis, wound infection, pulmonary dysfunction, and incisional hernia have all been noted.

As laparoscopy has matured as a technique, procedures have become more complex, and patients are more likely to be older and more debilitated than in the past. Despite the increasing complexity of patients and procedures, complications and mortality have decreased for most procedures.