Cardiovascular autonomic function in patients with hemodynamic instability at induction of capnoperitoneum: a case-control study

Background: This study hypothesized that patients in
whom bradycardia and hypotension develop with induction
of positive-pressure capnoperitoneum have an
underlying autonomic cardiovascular dysfunction.
Methods: A case–control study was conducted to examine
the baseline autonomic function of patients in
whom bradycardia and hypotension develop with induction
of positive-pressure capnoperitoneum. The
control group consisted of patients who maintained
normal cardiac rhythm and blood pressure during the
same procedure. Two groups of tests were performed:
bedside stress tests of cardiovascular autonomic function
(response graded 1 (normal) to 4 (severely abnormal)
and heart rate variability analysis (spectral and
time domain components).
Results: The study evaluated 6 patients in the bradycardia
group and 10 in the control group. The group in
whom bradycardia had developed scored significantly
worse on the bedside stress tests than the control group
(for grades I to IV: v2 = 6.5, p = 0.022; for trend:
v2 = 5.6, p = 0.018). In contrast, both groups had
similar baseline autonomic tone, as measured by heart
rate variability.
Conclusions: Patients in whom bradycardia and hypotension
develop with induction of positive-pressure
capnoperitoneum have cardiovascular autonomic dysfunction,
which is identifiable by bedside stress tests of
autonomic function.