Background:
@EN This study was to evaluate the relationship of preoperative autonomic tests to the labetalol effect on cardiovascular responses to intubation of geriatrics(65 years of age or older, n=23). The autonomic tests consisted of heart rate response
to
deep
breathing(HRDB), Valsalva ratio(VR), 30/15 ratio(30/15) to assess parasympathetic function. The systolic blood pressure change response to standing(△ SBP) and mean arterial pressure change response to standing(△MAP) were to assess sympathetic
function.
@ES Methods:
@EN These autonomic tests were taken preoperatively. At a separate time, labetalol 1.0mg/kg was injected as a bolus 3 minutes before induction with thiopental sodium (4mg/kg), succinylcholine (1mg/kg). The anesthesia was maintained with
enflurane,
oxygen, nitrous oxide and vecuronium (0.08 mg/kg). The blood pressure and heart rate(HR) were recorded at one minute intervals for 5 minutes after intubation. The hypotension(SBP<90mmHg) or bradycardia (HR<60 beats/minute) were recorded for 10
minutes
after intubation. After anesthesia, they were divided two groups according to presence(old abnormal group, n=10, who required intraoperative vasopressors) or absence(old normal group, n=13, who did not require intraoperative vasopressors) of
hypotension
or bradycardia.
@ES Results:
@EN The VR and △MAP revealed significant correlation with SBP and HR after intubation and 5 minutes later(p<0.05). The autonomic test results revealed significant autonomic dysfunction(p<0.05) among old abnormal group compared with old normal
group. HR
and SBP declined to a greater degree(p<0.05) during induction of anesthesia in old abnormal group compared with old normal group. There was less(p<0.05) increase in the same parameters following intubation in old abnormal group. The highest
sensitive
autonomic test was VR and the highest specific autonomic test was △MAP.
@ES Conclusion:
@EN Geriatric patients are at increased risk for cardiovascular instability during intubation.
The preoperative evaluation with autonomic tests may be useful in identifying those at high risk for perioperative hypotension or bradycardia when pre-induction intravenous labetalol 1.0mg/kg is indicated
|