Wednesday, June 30, 2010

Use of Anesthesia Services for Routine Gastrointestinal Endoscopy

Use of Anesthesia Services for Routine Gastrointestinal Endoscopy

Key Points:

Sedation-related risk factors, the depth of sedation, and the urgency of the endoscopic procedure
all play important roles in determining whether the assistance of anesthesia personnel is needed.
Sedation related risk factors include significant medical conditions such as extremes of age,
severe pulmonary, neurological, cardiac, renal, or hepatic disease, abuse of drugs or alcohol,
high tolerance to drugs due to chronic pain syndrome, uncooperative patients, or a potentially
difficult airway for intubation or ventilation.

Sedation and analgesia comprise a continuum of states ranging from minimal sedation
(anxiolysis) through general anesthesia. Definitions of levels of sedation–analgesia, as developed
by the American Society of Anesthesiologists (ASA); approved by the ASA House of Delegates
October 13, 1999 (11) and adopted by the ASA, are:

• Minimal Sedation (Anxiolysis) = a drug-induced state during which patients respond
normally to verbal commands. Although cognitive function and coordination may be
impaired, ventilatory and cardiovascular functions are unaffected.

• Moderate Sedation/Analgesia (Conscious Sedation) = a drug-induced depression of
consciousness during which patients respond purposefully to verbal commands, either
alone or accompanied by light tactile stimulation. No interventions are required to
maintain a patent airway, and spontaneous ventilation is adequate. Cardiovascular
function is usually maintained.
• Deep Sedation/Analgesia = a drug-induced depression of consciousness during which
patients cannot be easily aroused but respond purposefully following repeated or painful
stimulation. The ability to independently maintain ventilatory function may be impaired.Patients may require assistance in maintaining a patent airway, and spontaneous  ventilation may be inadequate. Cardiovascular function is usually maintained.

• General Anesthesia = a drug-induced loss of consciousness during which patients are not
arousable, even by painful stimulation. The ability to independently maintain ventilatory
function is often impaired. Patients often require assistance in maintaining a patent
airway, and positive pressure ventilation may be required because of depressed
spontaneous ventilation or drug-induced depression of neuromuscular function.
Cardiovascular function may be impaired.

Because sedation is a continuum, it is not always possible to predict how an individual patient
will respond. Hence, practitioners intending to produce a given level of sedation should be able
to rescue patients whose level of sedation becomes deeper than initially intended. Individuals
administering Moderate Sedation/Analgesia (Conscious Sedation) should be able to rescue
patients who enter a state of Deep Sedation/Analgesia, while those administering Deep
Sedation/Analgesia should be able to rescue patients who enter a state of general anesthesia.
Monitoring of patient response to verbal commands should be routine during moderate sedation,
except in patients who are unable to respond appropriately (e.g., young children, mentally
impaired or uncooperative patients), or during procedures where movement could be detrimental.
During deep sedation, patient responsiveness to a more profound stimulus should be sought,
unless contraindicated, to ensure that the patient has not drifted into a state of general anesthesia.
Note that a response limited to reflex withdrawal from a painful stimulus is not considered a
purposeful response and thus represents a state of general anesthesia.

An anesthetic agent such as propofol can be useful in certain patients undergoing endoscopic
procedures. However, clinically important benefits have not been consistently demonstrated in
average risk patients undergoing standard upper and lower endoscopy. In a randomized study
(5), 90 patients received a bolus administration of propofol or midazolam both before and during
upper endoscopy. The propofol treatment arm was superior in terms of patient tolerance,
maximum level of sedation achieved, and shorter recovery room times, although amnesia for the
procedure and perceived patient discomfort were not different. The ability of the endoscopist or
the facility to speed the recovery time so that more procedures can be accomplished in a given
time is an economic issue. It does not bear on the medical necessity of deep sedation/analgesia
for routine, low-to-average risk endoscopy procedures.

In a comparison of the combination of propofol and fentanyl with midazolam and meperidine in
a nonrandomized group of 274 patient undergoing upper endoscopy and colonoscopy, the group
receiving propofol and fentanyl had better patient comfort and deeper sedation without an
increase in untoward side effets. There was not, however, a significant difference in the recovery
times between the two groups (2). Sipe, et al. (18) randomized 80 patients undergoing
colonoscopy to combination midazolam/meperidine versus propofol. The propofol group had a
greater depth of sedation, modest improvement in satisfaction scores, and faster post procedure
recovery times. However, a prior randomized study of sedation for colonoscopy in 57 patients
did not find a benefit for propofol/fentanyl over diazepam/meperidine or midazolam/fentanyl in
terms of sedation, analgesia, recovery rate, or incidence of side effects. (7) Taken together, these
studies have not shown a convincing benefit for propofol when used for standard upper and lower endoscopy. Further randomized controlled trials are needed. Therefore, the routine
assistance of anesthesia personnel for average risk patients undergoing standard upper and lower
endoscopic procedures in not warranted and is not considered medically necessary.

Two randomized controlled trials in 80 and 196 patients respectively, have shown that propofol
has more clinically significant advantages when used for prolonged and therapeutic procedures
such as ERCP. (10)

Various individual factors such as age, developmental level, and previous experience determine
how a child responds to painful procedures. Some children may require deeper sedation for
procedures.

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