Transesophageal echocardiographic assessment of left ventricular function in response to labetalol for control of postoperative hypertension

Cerebral Blood Flow Assessed with Phase-contrast Magnetic Resonance Imaging during Blood Pressure Changes with Noradrenaline and Labetalol: A Trial in Healthy Volunteers

BACKGROUND

Adequate cerebral perfusion is central during general anesthesia. However, perfusion is not readily measured bedside. Clinicians currently rely mainly on mean arterial pressure (MAP) as a surrogate, even though the relationship between blood pressure and cerebral blood flow is not well understood. The aim of this study was to apply phase-contrast magnetic resonance imaging to characterize blood flow responses in healthy volunteers to commonly used pharmacologic agents that increase or decrease arterial blood pressure.

METHODS

Eighteen healthy volunteers aged 30 to 50 yr were investigated with phase-contrast magnetic resonance imaging. Intra-arterial blood pressure monitoring was used. First, intravenous noradrenaline was administered to a target MAP of 20% above baseline. After a wash-out period, intravenous labetalol was given to a target MAP of 15% below baseline. Cerebral blood flow was measured using phase-contrast magnetic resonance imaging and defined as the sum of flow in the internal carotid arteries and vertebral arteries. Cardiac output (CO) was defined as the flow in the ascending aorta.

RESULTS

Baseline median cerebral blood flow was 772 ml/min (interquartile range, 674 to 871), and CO was 5,874 ml/min (5,199 to 6,355). The median dose of noradrenaline was 0.17 µg · kg-1 · h-1 (0.14 to 0.22). During noradrenaline infusion, cerebral blood flow decreased to 705 ml/min (606 to 748; P = 0.001), and CO decreased to 4,995 ml/min (4,705 to 5,635; P = 0.01). A median dose of labetalol was 120 mg (118 to 150). After labetalol boluses, cerebral blood flow was unchanged at 769 ml/min (734 to 900; P = 0.68). CO increased to 6,413 ml/min (6,056 to 7,464; P = 0.03).

CONCLUSIONS

In healthy, awake subjects, increasing MAP using intravenous noradrenaline decreased cerebral blood flow and CO. These data do not support inducing hypertension with noradrenaline to increase cerebral blood flow. Cerebral blood flow was unchanged when decreasing MAP using labetalol.

EDITOR’S PERSPECTIVE

Acute pulmonary edema due to severe preeclampsia in advanced maternal age women

OBJECTIVE

Acute pulmonary edema is a rare complication in women with preeclampsia especially at advanced maternal age. We aimed to determine the cardiovascular hemodynamics in advanced maternal age women who developed acute pulmonary edema and preeclampsia.

STUDY DESIGN

Retrospective cohort study of women aged over 45 years giving birth at single university affiliated tertiary medical center which developed acute pulmonary edema due to severe preeclampsia. Clinical features were identified in order to predict and potentially prevent this severe complication of pregnancy.

MAIN OUTCOME MEASURES

Advanced maternal age women who developed acute pulmonary edema due to preeclampsia.

RESULTS

Overall, during the study period 90,540 women delivered in our hospital, of them, 540 women (0.6%) above the age of 45 years gave birth. Of those, 67 women (12.4%) had preeclampsia in which 4 women (6%) were complicated with acute pulmonary edema. The common clinical relevant characteristics for all four women were: preterm delivery by cesarean section for preeclampsia with severe features, non-restrictive fluid management around the time of delivery, post-partum pain control medication with non-steroidal anti-inflammatory drug, blood pressure stabilization with oral labetalol and a sudden hemodynamic deterioration to hypertensive crisis and pulmonary edema between post-operative days 4-9.

CONCLUSION

Although the precise trigger for the sudden presentation of acute pulmonary edema remains unknown, we suggest that there is a multi-factorial combination of etiologies that are common to women of advanced maternal age and women with preeclampsia that could have contributed to the development of pulmonary edema.

Cardiopulmonary compromise after use of topical and submucosal α-agonists: Possible added complication by the use of β-blocker therapy

We report the specifics of 12 cases of severe hypertension after the intraoperative use of topical phenylephrine, submucosal epinephrine, or both. Ten of these 12 patients also developed severe pulmonary edema. Seven of the twelve were treated with β blockers; 3 of whom suffered cardiac arrest. We propose a common mechanism: the vasoconstrictors caused systemic hypertension, increased left ventricular afterload, decreased left ventricular compliance, and decreased cardiac output. In those patients treated with β blockers, decreased contractility and inability to increase heart rate further compromised cardiopulmonary function. (Otolaryngol Head Neck Surg 1997;117:56–61.)

Assessment of left ventricular function and hemodynamics with transesophageal echocardiography

Transesophageal echocardiography (TEE) plays an important role in the evaluation of left ventricular function and hemodynamics in the critical care setting. The technique provides immediate data regarding regional myocardial ischemia, global ventricular function, volume, and the presence of cardiac tamponade. This article outlines the role of TEE in the evaluation of left ventricular function in the intensive care unit and presents practical information for the use of TEE in evaluating systolic function, diastolic function, and cardiac tamponade.

Labetalol overdose successfully treated with amrinone and alpha-adrenergic receptor agonists

Circulatory collapse and obtundation occurred in a 37-year-old woman following an iatrogenic overdose of labetalol. Conventional therapy with glucagon and alpha-adrenergic receptor-stimulating agents was ineffective in raising the patient's cardiac output or improving her mental status despite increasing the arterial pressure. The administration of amrinone was temporally associated with significant increases in the cardiac output accompanied by improved mental status. This case suggests that amrinone may be effective adjunctive therapy for beta-adrenergic receptor blocker overdoses by reversing their negative inotropic effects.