In this episode, I’ll discuss fentanyl-induced chest wall rigidity.
Fentanyl is an ideal opioid to use in critically ill patients due to its relatively quick onset and offset. Fentanyl also has minimal histamine release and resulting effects on hemodynamics when compared with other opioids.
A known but rare complication of IV push fentanyl is chest wall rigidity. This is often thought to result from overly rapid administration of high doses of fentanyl, but a few cases have been reported with lower doses given slowly.
Chest wall rigidity can be recognized by the sudden cessation of movement of a patient’s chest wall, even during bag valve mask ventilation.
The chest wall rigidity can result in low chest wall compliance and make ventilating a patient with a bag-valve mask impossible.
The mechanism that causes chest wall rigidity from fentanyl is not known.
As discussed in episode 354, we know from a study of healthy male volunteers that when rigidity occurs, it starts 3 +/- 0.9 (range 1-4) minutes after the peak plasma fentanyl concentration and lasts for 11.5 +/- 5.8 (range 7-23) minutes.
Of 12 healthy adult males who were given IV fentanyl at a rate of 150 micrograms/minute until a total of 15 micrograms/kg had been administered, half developed chest wall rigidity.
This duration of 11.5 minutes is far longer than the safe apnea time for even a healthy patient. Therefore chest wall rigidity that doesn’t respond to rescue ventilation can require immediate intubation and mechanical ventilation to avoid anoxic brain injury or death.
Whether or not midazolam given with fentanyl attenuates or potentiates chest wall rigidity is controversial, with case reports suggesting either scenario could be true.
Many case reports describe that naloxone, even in doses as low as 0.2 mg, reverses the effects of fentanyl on the chest wall.
Neuromuscular blockade, with subsequent endotracheal intubation and mechanical ventilation is also a treatment commonly employed to treat chest wall rigidity from fentanyl.
Most authors recommend that if a patient with chest wall rigidity from fentanyl is treated successfully with naloxone, they should be observed closely for several hours as the naloxone would be expected to wear off faster than the fentanyl and it is unknown if rigidity could recur.
Some authors have also recently suggested that chest wall rigidity from illicit fentanyl may be a contributing factor in the cause of many opioid related deaths. In 48 fentanyl related deaths investigated, half did not have detectable levels of the metabolite norfentanyl. This suggests a very rapid death, which would be consistent with the hypothesis of acute chest rigidity.
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