To the Editor:
We thank Dr Reinertson for his kind words. Urban legend is an apt description of some of the repeated hyperbole surrounding suspension trauma and its treatment.
Dr Reinertson proposes a plausible alternative cause for rhabdomyolysis in the suspended person we describe. 1 Exertional rhabdomyolysis is associated with strenuous exercise, especially with eccentric (muscle lengthening) movements that could be part of a struggle to get up a rope. 2 Interestingly, it has not been associated with renal failure, possibly because the athletes and subjects described were in a better physiologic state when they exercised.3,4 Our patient's creatinine went from 0.9 mg/dL to 1.3 mg/dL, representing mild kidney injury. But while we don't believe that our patient was significantly hypothermic, he was most likely hypovolemic from cold diuresis and from suspension itself, which would put him at risk for acute kidney injury. In suspension trauma, hypovolemia or dehydration are relative terms. Lab studies do show shift of volume to the lower extremities, which would have “adequate” volume (albeit potentially deoxygenated) while upper extremities and internal organs might well have inadequate circulation.
Dr Reinertson also suggests that some cases of rhabdomyolysis after passive suspension are due to local trauma. This is supported by Flora and Holzl's series in which survivors with kidney injury had sufficient trauma to have brachial plexus injuries. 5 It is also supported by the short hang times for some of these individuals. However, although it is hard to determine too much from the collection of retrospective cases of survivors, it appears that rhabdomyolysis becomes more frequent with longer hang times, suggesting that prolonged suspension is still a causative factor.
The question of deoxygenated blood is interesting. With insignificant venous return—the proposed mechanism for suspension trauma—blood could indeed become deoxygenated. The question is how much this static blood would eventually impede arterial flow. Dr Reinertson feels that, in anyone not syncopal, there must be arterial flow adequate to prevent muscle damage. He may be right, but we have found no data to clarify this one way or the other. Fortunately, with Doppler technology, this is an answerable question. We hope that someone will study it in a lab setting.
We agree that rhabdomyolysis is not inevitable in cases of prolonged passive suspension. When it does happen, the pathophysiology is likely multifactorial. We do believe it is a common-enough occurrence, whatever the cause, that field management should include early fluid resuscitation to prevent renal failure and treat possible hyperkalemia.