Читать книгу Practical Pediatric Gastrointestinal Endoscopy - Группа авторов - Страница 33

There are four levels of sedation defined by the American Society of Anesthesiologists (ASA), and these may be thought of as a continuum: minimal sedation (anxiolysis), moderate sedation and analgesia (conscious sedation), deep sedation (unconscious), and general anesthesia.

Anxiolysis is a drug‐induced state where motor and cognitive functions may be impaired, but the patient responds to verbal commands. Ventilatory and cardiovascular functions are largely unaffected with anxiolysis.

During moderate sedation, also known as conscious sedation, the child may respond purposefully to verbal commands (e.g., “open your eyes”) with or without light tactile stimulation. Airway and cardiovascular function are unaffected; however, endoscopy presents a unique challenge as the tools employed for the procedure can predispose some patients to airway obstruction. This is especially relevant in smaller children, where the trachea is smaller and with soft cartilaginous rings, and more prone to obstruction than that of an older child with a larger, more rigid airway. In some cases where there is considerable risk of airway obstruction with endoscopy, intubation may be indicated. Due to the relative size of the endoscope and discomfort involved in its placement, moderate sedation is rarely successful in children when performing this procedure, unless the patient is old enough to cooperate.

Deep sedation refers to a state in which the child responds only to deep or repeated stimulation, and ventilation may be impaired. Patients may require assistance with ventilation or maintaining an airway, but cardiovascular function is usually maintained. One can anticipate a partial or complete loss of airway protective reflexes in this state, and preparations must be in place to accommodate for this.

General anesthesia describes a state in which there is no response to painful stimuli, and ventilation assistance is usually required due to depressed consciousness and neuromuscular function. Hemodynamic function may be compromised as well.

General anesthesia with endotracheal intubation is mandatory in patients graded III or higher according to the ASA physical status classification III (Box 4.1), in emergent procedures such as gastrointestinal bleeding or foreign body removal or more complex procedures such as endoscopic gastrostomy insertions or stenosis dilations. In interventional endoscopic procedures, a tracheal tube provides some airway protection against aspiration.

Sedation and analgesia for diagnostic and therapeutic endoscopy in children carries a number of considerations dependent on differences in age, developmental status, and presence of co‐morbidities. One of the goals in sedating children is to control behavior, which is entirely dependent on their chronological and developmental age. Children younger than 6 or 7 years often require a deep level of sedation in order to safely complete an uncomfortable procedure, where respiratory drive, airway patency and protective reflexes may be compromised. Studies have shown that it is common for children to pass from the intended level of sedation into a deeper state in an effort to control their behavior, where physiologic compromise may occur. In order to provide the safest conditions for a child undergoing sedation, it is important to understand the definitions pertaining to level of consciousness, as well as having the ability to rescue a child from a deeper level of sedation than was intended.