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May
1998
Choral
Hydrate Sedation: The Additive Sedative and Respiratory Depressant Effects
of Nitrous Oxide
Litman
RS, Kottra JA, Verga KA, Berkowitz RJ, Ward DS; Anesth Analg 1998;86:724-8.
[ see
abstract below ]
One of the important issues faced by departments of anesthesiology is
to assist hospitals in developing institution guidelines for monitoring
pediatric and adult patients who undergo procedures which require sedation.
Dentists in particular, although active in developing monitoring guidelines
within their specialties, have been less than specific in defining levels
of sedation in practice when compared with the written description.
There are many papers describing "conscious sedation" with drug combinations
that most anesthesiologists would consider as more likely to produce "deep
sedation" or even "general anesthesia" (See Dr. Coté's previous reviews
of Guidelines for Monitoring and Management
of Pediatric Patients During and After Sedation for Diagnostic and Therapeutic
Procedures, Drugs for Pediatric Emergencies,
and ASA Update for Pediatrics). One favorite
sedation regimen for the pediatric dentist is the combination of a "light
sedative", often chloral hydrate, and the use of 30-50% nitrous oxide. It
is felt that the combination of light sedation and nitrous oxide does not
require monitoring to the levels described in the American Academy of Pediatric
Guidelines.
Litman et al have performed a wonderful service by providing us with the
ammunition to encourage dentists to appropriately monitor their patients.
Now there is science to confirm that a routine dose of chloral hydrate,
when combined with nitrous oxide 30% or 50%, will produce deep sedation
in many and even a state of general anesthesia in some children. This
work confirms a previous dental report (predating pulse oximetry) which
found that some children who had received the combination of chloral hydrate
and nitrous oxide were unable to spontaneously unobstruct their airway
(Moore PA et al: Sedation in pediatric dentistry: a practical assessment
procedure. J Am Dent Assoc. 1984:109;564-566). This current study
of chloral hydrate is consistent with Litman's previous study describing
a similar interaction between nitrous oxide and oral midazolam (Litman
RS et al: Levels of consciousness and ventilatory parameters in young
children during sedation with oral midazolam and nitrous oxide. Arch
Pediatr Adolesc Med 1996:150;671-675).
The bottom line is, regardless of the class of sedative, nitrous oxide
even in relatively low concentrations can produce both deep sedation and
in some a state of general anesthesia. It is time for everyone to admit
that the phrase "conscious sedation" for the pediatric patient is an oxymoron
and that children need to be monitored appropriately to their level of
sedation. Thank you Dr. Litman and colleagues for enlightening us and
our colleagues in dentistry.
Return to the Current
Literature Review Front Page , or read the abstract:
ABSTRACT
The combination of choral hydrate and nitrous oxide (N2O) is
often used for sedation in pediatric dentistry. The purpose of this study
was to determine the extent to which N2O increases the level of sedation
and respiratory depression in children sedated with choral hydrate.
Thirty-two children, 1-9 yr, received choral hydrate, 70 mg/kg (maximum
1.5 g), and then received N2O (30% and 50%). Hypoventilation
(maximal PETCO2 > 45mm Hg) occurred in 23 (77%) children during
administration of choral hydrate alone, in 29 (94%) breathing 30% N2O (P
= 0.08 versus control). Mean PETCO2 was increased during 30%
(P= 0.007) and 50% (P = 0.02) N2O administration.
Using choral hydrate alone, 8 (25%) children were not sedated, 10 (31%)
were consciously sedated, and 14 (44%) were deeply sedated. Using 30% N2O,
2 children (6%) were not sedated, 0 were consciously sedated, and 29 (94%)
were deeply sedated (P < 0.0001). Using 50% N2O, 1 child (3%)
was not sedated, 0 were consciously sedated, 27 (94%) were deeply sedated,
and 1 (3%) had no response to a painful stimulus (P < 0.0001).
We conclude that the addition of 30% or 50% N2O to choral hydrate
often causes decreases in ventilation and usually results in deep, not conscious,
sedation in children.
Implications: Pediatric sedation in the dental office often consists
of nitrous oxide (N2O) after choral hydrate premedication. We
found that the addition of 30% or 50% N2O to choral hydrate often
causes decreases in ventilation and usually results in deep, not conscious,
sedation in children.
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