Anesthesia in Laparoscopic Surgery - Dr. R.K. Mishra

Anesthesia in Laparoscopic Surgery

The anesthetic problems during minimal access surgery are related to the cardiopulmonary effects of pneumoperitoneum, carbon dioxide absorption, extraperitoneal gas insufflation, venous embolism, and inadvertent injuries to intraabdominal organs. Optimal anesthetic care of patients undergoing laparoscopic surgery is very much important. Good anesthetic techniques facilitate risk-free surgery and allow early detection and reduction of complications.

In young patients, fit for diagnostic laparoscopy, general anesthesia is the preferred method and does not impose any increased risk. Adequate anesthesia and analgesia are essential and endotracheal intubation and controlled ventilation should be considered. The pneumoperitoneum can be created safely under local anesthesia provided that the patient is adequately sedated throughout the procedure. For successful laparoscopy, under local anesthesia, intravenous medication for sedation should be given.

Regional Anesthesia

Spinal anesthesia is reported enthusiastically for diagnostic laparoscopy without significant complications. Regional anesthesia may be useful for pelvic procedures but if high block is used it interferes with the respiratory status of the patient. Bilateral lower intercostal nerve block has also been used, but it is time-consuming and it can cause pneumothorax.

General Anesthesia

Many centers use general anesthesia as a routine in all laparoscopic cases. General anesthesia is advisable in pediatric patients also. Endotracheal anesthesia with muscle relaxants and controlled ventilation is generally preferred especially in elderly or high-risk cases.

Anesthesia for laparoscopy can be achieved with a variety of agents and techniques. General anesthesia using a balanced anesthesia technique including intravenous induction agents like Thiopentone, propofol, etomidate, and inhalational agents like nitrous oxide, isoflurane can be used. An ideal general anesthesia machine should have:

•    Spontaneous Breathing with Computerized Ventilation
•    Manual Ventilation
•    Volume Controlled Ventilation
•    Pressure Controlled Ventilation
•    Computerized Pressure Support

 Ideal Anaesthesia Machine
  Ideal Anesthesia Machine

A variety of muscle relaxants including succinylcholine, mivacurium, atracurium, vecuronium is available for rapid recovery and cardiovascular stability. Total intravenous anesthesia using agents like propofol, midazolam, and ketamine, alfentanil, and vecuronium has been reported for outpatient laparoscopy.

Few anesthetist advocates open anesthesia, which avoids the post-intubation sore throat and laryngeal sequelae, but this is associated with a risk of inhalation of gastric content and gastric distension. The chances of the latter are not by the passage of a nasogastric tube. Halothane should be avoided or used sparingly in patients with several previous operations and in the presence of liver disease.

Local Anesthesia

Many surgeons have done a sufficient number of laparoscopic procedures under local anesthesia with intravenous sedation and results are encouraging with minimal morbidity and negligible mortality. Laparoscopy under local anesthesia should be performed with an anesthetist being present to monitor the patient’s cardiac and respiratory functions. Intravenous sedation should be administered with IV. diazepam and pethidine. A preferred local anesthetic agent is 1 percent lignocaine without adrenaline or lidocaine without epinephrine. The anesthetic agent should be administered at the sites of insertion of the needle, and all trocars. If local anesthesia is used, the anesthetist should perform valuable service by providing “vocal local technique”.

The anesthetist should talk constantly to the patient that everything is going well. One of the most difficult situations of local anesthesia is that the patient, rather than the surgeon, becomes the center of attraction for all noises and comments made in the room during surgery. It is important to understand that under local anesthesia adequate sedation and analgesia are administered to keep the patient somnolent but responsive. Continuous monitoring of all the vitals is essential throughout the procedure. Secondly, it is essential that a pneumoperitoneum of approximately 1.5 to 3 liters be present under pressure.

Anesthetist’s Role in Laparoscopy

The role of the anesthetist in laparoscopic surgery is vital. The laparoscopic surgery should never be performed if anesthetist has no experience in minimal access surgical anesthesia. It is up to the anesthetist to identify whether he is capable of performing realistically without compromising the safety of the patients. It is only on these clearly established bases that safe laparoscopy can be contemplated.

The following monitoring device should routinely use at the time of minimal access surgical general anesthesia:

•    Electrocardiogram
•    Sphygmomanometer
•    Airway pressure monitor
•    Pulse oximeter
•    End-tidal CO2 concentration (PETCO2) monitor
•    Peripheral nerve stimulator
•    Body temperature probe.

Balanced anesthesia using an appropriate amount of muscle relaxant, intravenous and epidural narcotics, and artificial ventilation is essential to combat the insult and the effects of pneumoperitoneum, namely the resorption of carbon dioxide, diaphragmatic movement impairment and the reduction in lung volumes. Direct arterial pressure monitoring and records of blood pressure and blood gas estimation are needed. The CVP monitoring helps in assessing the preload status. ECG monitoring demonstrates rhythm status continuously.

Prophylactic heparin should be used in accordance with the prevention of deep venous thrombosis and subsequent pulmonary embolism. The use of intermittent inflated pneumatic cast compression helps in maintaining circulation in the legs during the operation. Now, epidural anesthesia is also considered as a safe alternative to general anesthesia for outpatient laparoscopy without associated respiratory depression.

Inoperative Complications

If anesthetic consideration is not taken properly arrhythmias have been associated with laparoscopy. The most common are junctional rhythms, bigeminy, and asystole. Bradycardia has been reported due to rapid insufflation especially in older patients. The increasing pressure on the peritoneum increases vagal tone and bradycardia may develop. This bradycardia may be increased secondary to the absorption of CO2. Atropine has proven effective in restoring the vagal tone. 

The development of a CO2 gas embolus is a rarely encountered emergency. It develops due to intravasations of CO2 used in laparoscopic surgery. Some apparent sign of air embolism includes a sudden drop in end-tidal CO2, a drop in blood pressure and development of an arrhythmia. A classic “water wheel” or “mill wheel” murmur will be heard in the cardiac auscultatory area. Should such an event be suspected further insufflation should be immediately stopped and abdomen should be deflated. The patient should be turned towards left and head down to deviate the bubbles of CO2 away from the heart. The patient should be hyperventilated with 100 percent O2. If a central line is present, aspiration of the embolus should be attempted.

Pulmonary edema can result from aggressive fluid replacement or irrigating fluid absorption. Fluid management is even more difficult in a gynecological procedure where hysteroscopy is combined. Pulmonary edema is prevented by monitoring fluid input and output. Intraoperative diuretics should be administered if a large discrepancy between fluid input and output is found. If a patient develops respiratory distress, pulmonary edema should always be considered. Rales couples with classic chest radiographic findings will confirm the diagnosis.

Patient Selection

•    Patients with cardiac pathology must be subjected to a thorough preoperative assessment taking the particular hemodynamic conditions imposed by laparoscopic surgery into account.

•    Patients presenting with decompensated congestive cardiopathy are at the highest risk of laparoscopic surgery because the hemodynamic repercussions would be too difficult to manage, even with the help of invasive monitoring techniques.

•    The increase in systemic vascular resistance and the oxygen requirements of the myocardium could be the risk factor in cardiac patients. For these patients, the postoperative benefits of laparoscopic surgery must be weighed against the intraoperative risks. Preoperative investigation in these patients enables this risk to be evaluated more closely. The cardiac reserve must be assessed carefully; in particular myocardial contractility and the ejection fraction should be estimated.

•    The drop in venous return during peritoneal insufflation is one of the important factors which are responsible for drop-in cardiac output during laparoscopic surgery. This drop-in venous return is more important when the hypovolemia develops due to excessive bleeding, indicating that hypovolemia is a contraindication, at least for as long as their circulating volume has not been restored to normal. This point is particularly important for ruptured ectopic pregnancy or during laparoscopic surgical exploration of abdominal injuries.

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