The goal of moderate sedation is to minimize the patient’s discomfort and anxiety experienced while undergoing invasive procedures. The specific objectives of sedation are mood alteration, maintenance of consciousness and cooperation, management of patient’s pain with minimal changes in vital signs, partial amnesia and a prompt, safe return to activities of daily living (Somerson, Husted, and Sicilia, 1995).
Moderate sedation is a drug-induced depression of consciousness during which patients respond appropriately to verbal commands, either alone or accompanied by light tactile stimulation. The ability to independently maintain ventilatory and cardiovascular function is retained. No interventions are required to maintain an adequate airway or pulmonary ventilation. Patients may require supplemental oxygen to maximize oxygenation but are able to maintain their airway and handle secretions independently. Correlates with a score of 4 on adult sedation scale.
The patient should retain the ability to independently and continuously maintain a patent airway and handle secretions without aspiration.
The transition from moderate sedation to deep sedation and from deep sedation to general anesthesia is a continuum. It can be difficult to predict and must be anticipated whenever sedation is administered. If this transition is not appreciated and appropriate interventions taken immediately, the patient’s condition can rapidly deteriorate resulting in hypoxia, respiratory arrest, cardiogenic shock, anoxic brain injury and even death. Close monitoring and frequent reassessment of the patient facilitates prompt determination of when the desired level of sedation is achieved and early recognition of adverse events.
Deep sedation is a drug-induced depression of consciousness during which patients cannot be easily aroused but respond appropriately to painful stimulation. The ability to independently maintain ventilatory function may be impaired. Patients may require assistance in maintaining an adequate airway, but ventilatory drive is usually sufficient to avoid the need for positive pressure ventilation.
Sedative drugs used in a manner, or in a dose that is intended to or may reasonably be expected to result in the loss of protective reflexes, may result in deep sedation. Use of such drugs in this manner shall require additional assessments, equipment, monitoring, documentation, outcomes evaluation and staff competencies beyond those required for moderate sedation. Correlates with a level of 5 on adult sedation scale.
General anesthesia is a drug-induced depressed level of consciousness during which patients are not arousable, even by painful stimulation. The ability to independently maintain ventilatory and cardiovascular function is often impaired. Patients often require assistance in maintaining an adequate airway, and positive pressure ventilation may be required because of depressed ventilatory drive or drug-induced depression of neuromuscular function. Only anesthesiologists are credentialed to provide general anesthesia. Correlates with a level of 6 on adult sedation scale.
Monitored Anesthesia Care (MAC) describes a specific anesthesia service in which an anesthesiologist has been requested to participate in the care of a patient undergoing a diagnostic or therapeutic procedure. It does not necessarily correlate with a specific depth of sedation. Monitored anesthesia care often includes the administration of doses of medications for which the loss of normal protective reflexes or loss of consciousness is likely. By definition, only clinical members of the Department of Anesthesiology provide monitored anesthesia care.