![]() ![]() ![]() I then calculated the sedation lag time and anesthetic awareness time for each simulated patient receiving rocuronium first and again receiving ketamine first. I assumed that each medication would be given sequentially and that administration would take 20 seconds for each medication. To assess the risk of anesthetic awareness, I simulated the onset times for ketamine and rocuronium 5000 times using Microsoft Excel to create random values with a normal distribution around each mean onset time. In a separate study, the onset of ketamine 2mg/kg IV was 46.05 seconds with a standard deviation of 1.93 seconds. In one of the most commonly cited papers comparing the onset of rocuronium to succinylcholine, the average onset of paralysis from rocuronium 1.2 mg/kg IV was 55 seconds with a standard deviation of 14 seconds. To determine the risk of anesthetic awareness from pushing rocuronium before ketamine, I performed a Monte Carlo analysis using 5000 simulated patients. The major risk that comes from giving rocuronium before ketamine is the risk of “anesthetic awareness.” That is, the risk the rocuronium kicks in before the ketamine does and the patient is paralyzed but not yet sedated. In this scenario, 50% of the safe apnea time is used up waiting for the rocuronium to work, leaving the physician with a very narrow window of time to place the airway without a risk of anoxic injury.īy reversing the usual order and giving rocuronium first, Josh points out that this sedation lag time should be minimized, assuming an onset of 50-60 seconds for rocuronium, an onset of 30-40 seconds for ketamine, and a few seconds to complete the administration of each drug.Īs some comments in Josh’s post point out, these onset times for rocuronium and ketamine are only averages – there are standard deviations that may make a difference in the calculation of the sedation lag time. This is problematic because the patient may become apneic from a fast ketamine push 1 minute before the intubating conditions are rendered ideal by rocuronium. With the traditional approach of giving ketamine before rocuronium, Josh estimates a 1 minute “sedation lag time” where the ketamine will kick in before the rocuronium. Such a patient has a very short “safe apnea time” of perhaps 2 minutes, beyond which if their airway is not secure they will likely suffer anoxic injury. In his post, Josh uses the example of a morbidly obese patient with hypoxic respiratory failure and an oxygen saturation of 96% despite maximal preoxygenation efforts. This is the reverse of the more common RSI practice of giving the sedative followed by the paralytic. Josh Farkas at wrote an excellent post discussing whether in certain scenarios rocuronium should be administered before ketamine in rapid sequence intubation. Subscribe on iTunes, Android, or Stitcher ![]()
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