First, the abolition of sweating from the upper body as well
as the axillae and both upper limbs may have significantly reduced
the capacity of the patient to lose heat through sweating during
exercise. Anhidrosis in the head and neck after sympathectomy affects a proprotion of patients, but is often neglected in
most reports of post-sympathectomy complications [
3]. The loss
of head and neck sweating in this patient may have further impaired
overall heat loss. However we would also note that the degree
of heat loss impairment after sympathectomy has never been quantified,
and its effect on body temperature during exercise remains to
be established.
Second, thoracic sympathectomy has been demonstrated to abolish
or alter sympathetic vasoconstrictive responses in the skin,
and this may contribute to
abnormal peripheral vascular responses to temperature [
4]
Paradoxically it has been suggested that in some cases there may be abnormal vasoconstriction rather than the expected vasodilation after sympathectomy. It is not impossible that such atypical peripheral vascular responses to rising body temperature may have contributed to impaired heat loss during exercise or to an inappropriate response to shock on the development of the heat stroke.
In the post-sympathectomy patient, the abnormal sympathetic skin response may lead to peripheral vascular failure or the reduced cardiac chronotropic response may impair the body’s capacity to compensate for shock. These may have contributed to the rapid development of shock and severe multiple organ dysfunction syndrome in this patient.
Third, it has been shown that thoracic
sympathectomy can impair the autonomic nervous system’s increase of the heart rate in response to exercise [
6]. Although absolute tachycardia is
not eliminated, given the endocrine and paracrine stimuli during
exercise, the maximum heart rate reached during exercise has
been shown to be
significantly reduced after sympathectomy. Thus for a given workload during exercise, there will be a relative
bradycardia. This may possibly affect the circulatory system’s
ability to convey heat from the body core to the extremities
for heat loss.
Is Previous Thoracic Sympathectomy a Risk Factor for Exertional Heat Stroke?
Alan D.L. Sihoe, FRCSEd(CTh)a,*, Raymond W.T. Liu, MRCPb, Alex K.L. Lee, MRCPb, Chak-Wah Lam, FHKAMb, Lik-Cheung Cheng, FRCSa
http://ats.ctsnetjournals.org/cgi/content/full/84/3/1025
