Definitions/spectrum of sedation to general anesthesia

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.

Assessing risk in the pediatric patient

The Pediatric Sedation Research Consortium (PSRC) is a collaborative of 40 hospitals and universities in the United States and Canada with a mission dedicated to understanding and improving the process of pediatric sedation and sedation outcomes. Member institutions prospectively enroll pediatric patients receiving sedation for all procedures outside the operating room, and the data are entered into a central database. This rich database has contributed a great deal to pediatric procedural sedation literature over the last 10 years.

Preparation

A thorough presedation assessment is crucial in order to identify patients at risk for adverse events. Sedation for endoscopy must be tailored for each individual, yet preparations should be approached in the same stepwise fashion for every patient. The components of a presedation evaluation should include (i) informed consent, (ii) verbal and written instructions for postprocedure issues, (iii) the child’s medical history, (iv) physical exam, and (v) a risk assessment.

Informed consent specific to the procedural sedation must be obtained and documented in accordance with institutional guidelines. Verbal and written instructions to the parent or guardian should include the objectives of the sedation as well as anticipated effects during and after the procedure. Patients must know whom to contact after the procedure if any medical issue arises after being discharged from the hospital

The medical history should focus on any current or past medical illnesses affecting the cardiovascular, respiratory, hepatic or renal systems, which may affect the child’s response to the medications chosen. Consultation with a pharmacist may be necessary when there is a concern for drug interaction. Previous experiences with procedures should be elicited in order to uncover events that the child may be predisposed to, and a family history regarding anesthesia should be obtained. A thorough history of allergies to any medications or foods is important. As an example, propofol is manufactured in an oil‐in‐water base with egg and soybean oil, and therefore is contraindicated for use in a patient with egg or soybean allergy.

The physical exam must include a complete set of vital signs, which includes temperature, heart and respiratory rate, blood pressure, and pulse oximetry. A current weight is needed for appropriate medication dosing. Particular attention must be paid to the oropharynx for findings such as micrognathia, facial dysmorphism, loose teeth, tonsillar hypertrophy, or any other condition which could affect the airway. Heart exam should focus on the presence of murmurs or gallops which could indicate anatomical or functional issues. The airway exam should focus on the presence of stridor or wheezing.

Risk assessment includes assigning an ASA physical status classification level (Appendix I). Children who are Class I and II are considered appropriate candidates for minimal, moderate, and deep sedation. Situations which would indicate consultation with an anesthesiologist would be ASA class III or IV, children with congenital heart or pulmonary disease, significant upper or lower airway obstruction (such as tonsillar hypertrophy or poorly controlled asthma), or morbid obesity. Neurologic conditions such as poorly controlled seizures, central apnea, or severe developmental delay are also considered high risk, and warrant consultation with appropriate specialty services.

Staffing and environment preparation

At a minimum, the staff required for pediatric endoscopy with procedural sedation consists of four individuals. In addition to the gastroenterologist and endoscopy nurse, there must be an anesthesiologist (in case of general anesthesia or sedation provided by anesthesiologist) or another practitioner dedicated to monitoring the patient, whose sole responsibility is to continually observe and respond to the patient’s vital signs, physiologic status, and level of sedation. The practitioner should be skilled in assessment of cardiopulmonary function: respiratory rate and depth, early recognition of cyanosis, perfusion, and pulse assessment. Optimally, this individual would have a dedicated sedation nurse but this may not be possible at some institutions. Whether the sedation practitioner is a physician, physician assistant or nurse practitioner, they should be PALS certified and have adequate specialized training in pediatric procedural sedation and rescue techniques. Regular maintenance of these skills is recommended.

The majority of procedures are performed in endoscopy suites, which must be appropriately equipped to perform sedations safely. A crash cart or kit should include age‐ and size‐appropriate equipment and medications necessary to resuscitate a child. Airway equipment must include size‐appropriate BVM, airway delivery devices, and intubating equipment with age‐appropriate endotracheal tube sizes and laryngoscope blades. Cardiorespiratory monitoring should include electrocardiography, respiratory tracing, pulse oximetry, capnography, and noninvasive blood pressure monitoring with size‐appropriate cuffs. An oxygen source and suction with catheters must be available. A defibrillator, with pediatric paddles and adhesive pads, should be accessible. There should be a protocol for accessing a higher level of care such as a pediatric intensive care or step‐down unit, and in nonhospital environments, a system for accessing ambulance services.

Anesthesia apparatus is essential for procedures in general anesthesia. It may be situated in the endoscopy suite or the endoscopy team may perform procedures in the operating theatre with a mobile endoscopic device.

During sedation and monitoring

Before the administration of medications, a baseline set of vital signs should be documented. The name, route, site, time, and dosage of all drugs administered should be recorded. Once medication administration has begun, level of consciousness and vital signs should be documented on a time‐based flow sheet every five minutes. The vital signs documented should include heart and respiratory rate, oxygen saturation, and blood pressure. Once the procedure is complete and no more medications are to be administered, vital signs should be documented every 15 minutes until the child awakens.

Whether administration of medications is performed by the gastroenterologist or the sedation practitioner, good communication is crucial in order to provide optimal procedural sedation. It is important in order to anticipate physiologic changes or the conclusion of the procedure, which could affect a decision to administer a dose of medication or not. Timing of medication administration should be predicated on anticipating patient responses, which is best performed by maintaining an awareness of the procedure through observation and communication. It is the responsibility of the individual monitoring the patient to alert the gastroenterologist to physiologic deterioration, and to temporarily stop the procedure if rescue measures are required.

The nature of gastrointestinal endoscopy mandates a discussion of the specific physiological considerations inherent to the procedure. For example, esophageal intubation can induce apnea and bradycardia due to stimulation of the laryngeal branch of the vagus nerve. Infants or children with spastic neuromuscular disorders are especially prone to this, due to their small size and high cricopharyngeal tone, respectively. When air is insufflated into the gastrointestinal tract, it has the potential to cause respiratory insufficiency. Excess air in the stomach can elevate the left hemidiaphragm, impeding respiratory excursion and subsequently tidal volumes, which can be deleterious for ventilation and oxygenation. The loss of functional residual capacity can subsequently cause hypoxemia from loss of alveolar recruitment, and positive pressure ventilation, along with gastric decompression, may be necessary to recover adequate oxygen saturation.

Mesenteric stretch can cause various degrees of abdominal discomfort in some individuals, and adequate analgesia is needed to blunt this response. Intense pain during a colonoscopy, for example, is a sign of excessive mesenteric stretching and requires not only adequate analgesia but immediate adjustment of endoscopic technique. This situation highlights the need for constant communication between the gastroenterologist and monitor, as adjustments must be made by both individuals for the best procedural conditions.

The issue of standard supplemental oxygen use is controversial. Due to the nature of the procedure, supplemental oxygen is often needed to maintain adequate oxygen saturations. It must be kept in mind that failure in ventilation may be masked by supplemental oxygen, due to the law of partial pressures in the alveoli.