Time to Renitrogenation After Maximal Denitrogenation in Healthy Volunteers in the Supine and Sitting Positions.

INTRODUCTION: Prior to intubation, preoxygenation is performed to denitrogenate the lungs and create an oxygen reservoir. After oxygen is removed, it is unclear whether renitrogenation after preoxygenation occurs faster in the supine vs the sitting position. METHODS: We enrolled 80 healthy volunteers who underwent two preoxygenation and loss of preoxygenation procedures (one while supine and one while sitting) via bag-valve-mask ventilation with spontaneous breathing. End-tidal oxygen (ETO2) measurements were recorded as fraction of expired oxygen prior to preoxygenation, at the time of adequate preoxygenation (ETO2 >85%), and then every five seconds after the oxygen was removed until the ETO2 values reached their recorded baseline. RESULTS: The mean ETO2 at completion of preoxygenation was 86% (95% confidence interval 85-88%). Volunteers in both the supine and upright position lost >50% of their denitrogenation in less than 60 seconds. Within 25 seconds, all subjects had an ETO2 of <70%. Complete renitrogenation, defined as return to baseline ETO2, occurred in less than 160 seconds for all volunteers. CONCLUSION: Preoxygenation loss, or renitrogenation, occurred rapidly after oxygen removal and was not different in the supine and sitting positions. After maximal denitrogenation in healthy volunteers, renitrogenation occurred rapidly after oxygen removal and was not different in the supine and sitting positions.

Wooden chest syndrome: Beware of opioid antagonists, not just agonists.

BACKGROUND: In a constantly increasing world of opioid addiction, naloxone has become a topic of great discussion and use. With seemingly minimal side effects, naloxone has become one of the most wellknown and widely used reversal agents for opioid intoxication. While more common effects of using naloxone include agitation, abdominal cramps, piloerection, diarrhea, nausea, and yawning, lesser known side effects involve muscle spasms, flushing, hyperreflexia in neonates, and seizures. This case study demonstrates a side effect of rigidity secondary to IV naloxone that has not previously been documented. CASE: A 56 year old man was brought in by EMS after being found unresponsive in a car with a bag of drugs beside him. He was given 0.5 mg naloxone IV by EMS and immediately brought to the hospital. On arrival, the pt was noted to have tight rigidity of his upper extremities, with severe flexion. This presentation was not noted before the delivery of naloxone by EMS. CONCLUSIONS: While this case highlights a patient with a rare side effect of naloxone, it reminds physicians that all medications come with a cost. Of course, ABCs remain the highest priority of resuscitation, however when administering a medication to reverse a drug overdose, it is important to keep in mind all possible consequences of said agent. Recognizing that complete muscle rigidity may remain a result of naloxone administration allows physicians to perhaps save patients from further medical workup.