Suxamethonium Dose in Morbid Obesity
Date First Published:
October 23, 2006
Last Updated:
April 11, 2007
Report by:
Stephen Fordham, ST3 Emergency Medicine (Torbay Hospital, Devon.)
Search checked by:
Chris Manlow, Torbay Hospital, Devon.
Three-Part Question:
In [obese adults] what [dose of suxamethonium] gives optimal [intubating conditions]?
Clinical Scenario:
An obese forty year old woman is brought in to the resuscitation room following a closed head injury, Her GCS is 6/15 and you need to urgently secure a definitive airway. The anaesthetist is busy so you have to proceed with the RSI alone and while drawing up the drugs the Nurse asks you what dose of Suxamethonium you would like. Her husband says she weighs 140kg. You wonder how best to calculate the dose of Suxamethonium to give optimal intubation conditions with shortest time to return of breathing should a failed intubation and ventilation scenario develop.
Search Strategy:
Medline 1966 to November week 1 2007 using Dialog Datastar Interface.
Search Details:
[ exp obesity-morbid OR exp obesity OR obese.mp OR obesity.mp ] AND [ exp succinylcholine OR exp neuromuscular depolarising agents OR succinylcholine.mp OR suxamethonium.mp ] AND [ exp intubation.intratracheal OR RSI.mp OR rapid sequence induction.mp OR rapid sequence intubation.mp OR intubation.mp ] Limit to Human and English Language.
Outcome:
Altogether 13 papers were found of which 1 presented the best evidence.
Relevant Paper(s):
| Study Title | Patient Group | Study type (level of evidence) | Outcomes | Key results | Study Weaknesses |
|---|---|---|---|---|---|
| The Dose of Succinylcholine in Morbid Obesity Lemmens HJ, Brodsky JB. 2006, USA | 45 morbidly obese adults scheduled for gastric bypass surgery | Randomised Double Blind Comparing Succinylcholine 1mg/kg ideal body weight, 1mg/kg lean body weight, 1 mg/kg total body weight |
Endotracheal Intubating Conditions | Significant improvement with 1mg/kg actual body weight p < 0.05. | Small number of patients Elective Surgery rather than Emergency Department patients |
Author Commentary:
After complete denitrogenation, the haemoglobin of an apnoeic morbidly obese adult will desaturate to hypoxaemic levels in <3-4 min. The recovery to 50% twitch height is thought to be time to functional recovery with regard to haemoglobin desaturation risk. In the smallest dose Suxamethonium group, 1mg/kg Ideal Body Weight, this did not occur for 5min, therefore this dose will provide less than ideal intubation conditions without protecting the morbidly obese patient from hypoxia if difficulty is experienced with intubation and ventilation.
Bottom Line:
In obese adult patients a Suxamthonium dose of 1mg/kg Total Body Weight gives optimal intubating conditions.
References:
- Lemmens HJ, Brodsky JB.. The Dose of Succinylcholine in Morbid Obesity