Anesthesiology 2005; 102:35– 40 © 2004 American Society of Anesthesiologists, Inc. Lippincott Williams & Wilkins, Inc.
Succinylcholine Dosage and Apnea-induced Hemoglobin
Desaturation in Patients
Mohamed Naguib, M.B., B.Ch., M.Sc., F.F.A.R.C.S.I., M.D.,* Abdulhamid H. Samarkandi, M.B., B.S., F.F.A.R.C.S.I.,†
Khaled Abdullah, M.B., B.Ch., M.Sc., A.B., M.D.,‡ Waleed Riad, M.B., B.Ch., M.Sc., A.B., M.D.,‡
Saleh W. Alharby, M.B., B.S., F.R.C.S. (Glas.)§
Background: The authors examined the notion that a reduc-
tion in succinylcholine dose from 1 mg/kg to 0.6 mg/kg would
allow a faster recovery of spontaneous ventilation and reduc-
tion in the incidence of hemoglobin desaturation during the
period of apnea in simulated complete upper airway obstruc-
tion situations.
Methods: This prospective, randomized, double-blind study
involved 60 patients. After preoxygenation to an end-tidal
oxygen concentration >90%, patients were anesthetized with
2 g/kg fentanyl and 2 mg/kg propofol. After loss of con-
sciousness, patients were randomly allocated to receive 0.56 or
1.0 mg/kg succinylcholine or saline (control group). Oxygen
saturation was monitored continuously at the index finger.
When the patient became apneic, the face mask was removed
and the patient’s airway was left unsupported. If the oxygen
saturation decreased to 90%, the face mask was reapplied, and
ventilation was assisted until the patient was awake. Time from
injection of the study drug to the first visible spontaneous
diaphragmatic movements was noted.
Results: Oxygen saturation decreased <90% in 45%, 65%, and
85% of patients in the control, 0.56 mg/kg, and 1.0 mg/kg
succinylcholine groups, respectively (P 0.03). Corresponding
times (mean SD) to spontaneous of diaphragmatic move-
ments were 2.7 1.2, 4.8 2.5, and 4.7 1.3 min, respectively.
These times were longer (P < 0.001) after either dose of succi-
nylcholine compared with controls.
Conclusions: Reduction in succinylcholine dose from 1.0 mg/kg
to 0.56 mg/kg decreased the incidence of hemoglobin satura-
tion <90% from 85% to 65% but did not shorten the time to
spontaneous diaphragmatic movements. A significant fraction
of patients would be at risk if there were failure to intubate and
ventilate whether succinylcholine is administered or not and
regardless of the dose of succinylcholine administered.
BASED on a mathematical model of hemoglobin desatu-
ration during apnea, Benumof et al.
1
predicted that in
the large majority of patients with 1 mg/kg succinylcho-
line-induced apnea, significant to life-threatening hemo-
globin desaturation will occur when ventilation is not
assisted. This theoretical analysis prompted two studies.
Heier et al.
2
reported that significant hemoglobin desatu-
ration (SaO
2
80%) occurred in one third of volunteers
during the period of apnea induced by 1 mg/kg succi-
nylcholine. In another report, Hayes et al.
3
concluded
that the use of 1.0 mg/kg succinylcholine “. . .may not
always prevent desaturation if there is a failure to intu-
bate and ventilate during a rapid sequence induction of
anesthesia.”
Consequently, the use of the 1.0 mg/kg dose of succi-
nylcholine has been questioned, and it was proposed
that a lower dose (0.6 mg/kg) of succinylcholine might
be a preferable alternative.
4,5
The premises of this pro-
posal are that intubating conditions
4
are not much dif-
ferent among patients who receive either 0.6 or 1.0 mg/kg,
and decreasing the dose of succinylcholine to 0.6 mg/kg
would allow a more rapid recovery of spontaneous venti-
lation. This, in turn, would decrease the incidence of life-
threatening hypoxemia in patients with unanticipated dif-
ficult airways when ventilation cannot be assisted. In light
of the aforementioned reports, we thought to determine
the validity of the hypothesis that a lower dose of succinyl-
choline would allow for a greater margin of safety in airway
management.
The aim of this prospective, randomized, double-blind,
placebo-controlled study was to compare the duration of
apnea and the incidence of hemoglobin desaturation
after administration of 0.0, 0.56, and 1.0 mg/kg of suc-
cinylcholine in healthy patients. The 0.56 mg/kg succi-
nylcholine is the calculated dose of succinylcholine that
is required to achieve acceptable intubating conditions
in 95% of patients at 60 s.
4
Materials and Methods
After obtaining institutional approval (King Khalid Uni-
versity Hospital, Riyadh, Saudi Arabia) and informed con-
sent, we studied 60 nonsmoking patients of both sexes
with American Society of Anesthesiologists physical
status I, aged 31.2 5.6 yr (mean SD) and weighing
74.4 11.4 kg. All patients underwent elective proce-
dures, had a normal airway anatomy, no neuromuscular,
renal, or hepatic disease, and none were taking any drug
known to interfere with neuromuscular function. No
premedication was administered. An infusion of lactated
Ringer’s solution was started before induction of anes-
thesia. Standard monitoring was used. Hemoglobin satu-
This article is featured in “This Month in Anesthesiology.”
Please see this issue of ANESTHESIOLOGY, page 5A.
* Professor, Department of Anesthesia, University of Iowa College of Medicine;
† Associate Professor, ‡ Consultant, § Associate Professor of Surgery, Department
of Anesthesia, King Saud University, Riyadh, Saudi Arabia.
Received from the Department of Anesthesia, King Khalid University Hospital,
Riyadh, Saudi Arabia. Submitted for publication April 28, 2004. Accepted for
publication September 3, 2004. Support was provided solely from institutional
and/or departmental sources. Presented at the annual meeting of the American
Society of Anesthesiologists, Las Vegas, Nevada, October 23–27, 2004. Richard B.
Weiskopf, M.D., served as Handling Editor for this article.
Address correspondence and reprint requests to Dr. Naguib: Professor, De-
partment of Anesthesiology and Pain Medicine, The University of Texas MD
Anderson Cancer Center, 1515 Holcombe Boulevard, Unit 42, Houston, Texas
77030. Address electronic mail to: Naguib@mdanderson.org. Individual article
reprints may be purchased through the Journal Web site,
www.anesthesiology.org.
Anesthesiology, V 102, No 1, Jan 2005 35
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