Do induced hypertension and hypotension affect stroke volume variation in man?

STUDY OBJECTIVE

To investigate changes in stroke volume variation (SVV) by both induced hypertension (pressor test) and hypotension (depressor test), and also by induced hypotensive anesthesia in patients with good cardiac function.

DESIGN

Prospective, controlled clinical study.

SETTING

University hospital.

PATIENTS

31 ASA physical status 1 and 2 patients, aged 39-62 years, who were scheduled for elective surgery.

INTERVENTIONS

We conducted three studies: a pressor test study, a depressor test study, and an induced hypotensive anesthesia study. In the pressor test, patients received a bolus of phenylephrine 0.001 mg/kg to increase systolic arterial pressure (SAP) by 30% to 40% compared with baseline. In the depressor test, patients received a bolus of nitroglycerine 0.005 mg/kg to decrease SAP by 30% to 40% compared with baseline. In the induced hypotensive anesthesia test, patients received intravenous (IV) nitroglycerine continuously until mean arterial pressure (MAP) was reduced to 60-70 mmHg.

MEASUREMENTS

When arterial pressure reached the target pressure for each study type, SVV and other parameters were recorded.

MAIN RESULTS

Induced hypertension (pressor test) decreased SVV, while induced hypotension (depressor test) and induced hypotensive anesthesia increased SVV.

CONCLUSIONS

SVV does not misinterpret preload dependency assessment of patients receiving medications to increase or to lower blood pressure.