Conscious Sedation for Intraoperative Neurosurgical Procedures

Abstract: Conscious sedation can be defined as adequate sedation while maintaining verbal rapport, amnesia with the relief of anxiety, and analgesic supplementation with local or regional blocks. Verbal communication with the patient is particularly important. One criterion affecting the use of conscious sedation is the surgeon's familiarity with the technique. The anesthesiologist should have a thorough knowledge of the sedatives and analgesics administered. The ability to establish a patent airway and maintain oxygenation and ventilation as needed is essential. Conscious sedation is not suitable for every patient. It is most appropriate for the cooperative patient who has a thorough understanding of the planned anesthetic and surgery. With this knowledge, the patient then accepts it willingly. Intraoperative monitoring should include noninvasive oxygen monitoring with a pulse oximeter, blood pressure, end-tidal carbon dioxide, temperature, electrocardiogram, and the use of a precordial stethoscope. Resuscitation equipment should be immediately available. An appropriate level of consciousness implies that patients will be able to control their own airway and take deep breaths, as necessary. Level of consciousness should be assessed every minute whenever medications are being titrated. With the administration of medication, the patient's responses to verbal commands are delayed and responses are frequently slowed or slurred. Light tactile stimulation may be required to get the patient's attention. Sedative medications depress both hypoxic and hypercapnic ventilatory drives. Monitoring of ventilation provides the earliest indication of adequate gas exchange. This may subsequently lead to alveolar hypoventilation, apnea, airway obstruction, and hypoxemia. With appropriate intervention when these signs are first observed, the risk of adverse outcomes may be significantly reduced. Medications administered may directly depress cardiac function, so patients may be at increased risk for developing cardiac dysrhythmias during conscious sedation. Supplemental oxygen should be continued into the postanesthetic care unit. Patients must be monitored during the recovery period to ensure that any adverse events are rapidly recognized and appropriately treated. It is important to establish appropriate guidelines for discharge from the recovery area or the intensive care unit. The underlying condition, the type of sedation administered, and the nature of the procedure must be considered. Patients who have received respiratory antagonists must be observed for an appropriate period of time to ensure that respiratory depression does not recur.

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