High IAP permits insufflated gas to gain access to tissue spaces, which explains occasional reports of pneumothorax and pneumomediastinum. A postoperative chest X-ray should be obtained.
Neurologic Effects Hypercapnia leads to increase in the systemic venous return, which combined with head down positioning lead to elevation in the ICP.
Endocrinologic Effects: Increase in the blood levels of ‘stress hormones’ i.e. insulin, cortisol, prolactin, epinephrine, blood levels of lactate, glucose and interleukin-6.
Perioperative Management: The child presenting for laproscopic surgery should be managed in exactly the same way as any child presenting for surgery.
Premedication: Oralmidazolam 0.5- 0.75mg/kg 15-30mins preoperatively. The use of atropine is associated with lower incidence of cardiovascular and airway complications. One advantage of anticholinergic premedication is to prevent vasovagal reflexes that are occasionally seen when the peritoneum is penetrated.
Anesthesia Techniques:
- Intravenous (Preferred if venous access has been secured à can be performed with minimal discomfort using EMLA, prilocaine gel)
- Inhalational – using sevoflurane or halothane in nitrous oxide and oxygen.
Emergency exploration: Rapid sequence intubation with cricoid pressure until a tracheal tube is securely in place to reduce the risk of pulmonary aspiration of gastric contents. Peripheral intravenous access should be obtained in all patients to allow continued hydration and drug administration.
Monitoring:
- Continuous E.C.G
- Automated N.I.B.P
- Pulse Oximetry
- Temperature
- Capnography
- Peripheral Nerve Stimulator
- Spirometry if available.
Small children have a high body surface area to mass ratio and little subcutaneous fat or body hair to retain heat. Continuous insufflation of large volumes of cold, non-humidified CO2 directly in to the abdominal cavity also contributes to a major risk of hypothermia. A warming mattress, heated humidifier or a convective forced air warmer might be used if available. An oro-nasogastric tube should be inserted after induction to permit deflation of the stomach, thus minimizing the chances of Verres needle accidentally perforating the inflated viscus.
Perioperative Care: A balanced technique with controlled ventilation using inhalational agents, intravenous opioids, non-depolarizing neuromuscular blocking agents is preferred. The chief difference in anesthetic management between Laproscopy and other abdominal procedures in children relates to the cardiorespiratory resulting from pneumoperitoneum and positioning. Ventilation should be controlled because this facilitates removal of exogenous CO2 and minimizes the reduction in FRC caused by a combination of increased IAP, Trendelenburg position and the use of volatile anesthetic agents. Minute ventilation needs to be increased by 20% or more to maintain normocapnia.
Pain Management: Pain following Laproscopy results from a variety of maneuvers
- Rapid distension of the peritoneum.
- Excitation of phrenic nerve with CO2.
- Unusual positions can stretch nerves.
Pain is best controlled by multimodal approach of local anesthetics, NSAIDs and opioids. Local anesthetics can be injected intraperitoneally as well as infiltrated on the puncture sites. NSAID can be given oral, rectal, intramuscular and intravenous routes.
Postoperative Nausea And Vomiting (PONV): PONV is a common complication following Laproscopy, delaying discharge from the hospital. A combination of drugs including 5-HT3 antagonist – ondansetron, dexamethasone and droperidol can be used.
Use Of LMA: The use of LMA is a remarkably useful adjunct to anesthesia for patients undergoing Laproscopy. Although aspiration with LMA is low there has been no report with Laproscopy and positive pressure ventilation.
High Risk Patients With Severe Myocardial Disease:
- Avoid anesthetics, which directly depress the myocardium, or release histamine. Sevoflurane may be the agent of choice.
- Preoperative atropine prevents bradycardia especially with noncompliant ventricles having a fixed stroke volume to maintain cardiac output.
- Avoid caudal/epidural as reduction in preload can lead to decrease in cardiac output.
- TEE is preferred over CVP due to its accuracy in preload and myocardial contractility.
- Pulmonary artery catheters for children weighing more than 15 kgs.
- Arterial catheter for blood gas monitoring may be considered.
Summary: Knowledge of pathophysiological changes, adequate monitoring and good planning makes anesthesia for Laproscopy safe in pediatrics.
