An observational study of the influence of "white-coat hypertension" on day-of-surgery blood pressure determinations.

BACKGROUND

Because decisions as to what range of intraoperative blood pressure (BP) is consistent with cerebral well-being are often made in reference to "baseline BP," we sought to determine whether day-of-surgery BPs accurately reflect baseline BP, as defined by ambulatory clinic BPs over the preceding 7 months.

METHODS

Consecutive patients (n=101) who were severely hypertensive (Severe-HTN), systolic (S)>160 mm Hg, or diastolic (D)>100 at first operating room BP (1st OR-BP) were identified retrospectively. Two additional groups were formed from patients whose 1st OR-BP was moderately hypertensive (Mod-HTN, systolic BP=140 to 159 and/or diastolic BP=90 to 99; and normotensive, SBP=110 to 139 and DBP<89). 1st OR-BP was compared with: (1) BP before transfer to the OR (Pre-OR-BP); (2) BP during ambulatory evaluation 1 to 30 days preoperatively (Preop-Eval-BP); and (3) Baseline-BP (average of at least 3 ambulatory clinic BPs during the preceding 7 months). Comorbidity data were collected.

RESULTS

For Severe-HTNs, 1st OR-BP, and Pre-OR-BP (expressed as mean arterial pressure) exceeded Baseline-BP by 16.4±11.6 (SD) and 5.2±11.6 (SD), respectively (P<0.05). Preop-Eval-BP was not different from Baseline-BP. For Mod-HTNs, 1st OR-BP exceeded Baseline-BP by 7.4±8.1 (SD) (P<0.05). But, Pre-OR-BP and Preop-Eval-BP did not differ from Baseline-BP. Among normotensives, 1st OR-BP was not different from Preop-Eval-BP or Baseline-BP. Hypertension, number of antihypertensive medications, vascular diagnoses (peripheral, coronary, cerebral), diabetes, and renal disease were more common in the hypertensive groups. The number of antihypertensive medications, a history of coronary disease, and insulin administration were predictors of an increase in 1st OR-BP over Baseline-BP.

CONCLUSIONS

For most patients whose 1st OR-BP is hypertensive, that BP is greater than ambulatory clinic BPs recorded during the preceding 7 months. For most patients with Severe-HTN at 1st OR-BP, day-of-surgery BPs overestimate Baseline-BP and reference to prehospitalization BPs is advisable. When 1st OR-BP is normotensive, that BP usually reflects Baseline-BP.