Intravenous labetalol for the treatment of hypertension after carotid endarterectomy

Peri-Procedural Management of Hemodynamic Instability in Patients Undergoing Carotid Revascularization

Acute perioperative changes in arterial pressure occur frequently, particularly in patients with cardiovascular disease or those receiving vasoactive medications, or in relation to certain cardiovascular surgical procedures. Hemodynamic Instability (HI) are common in patients undergoing carotid revascularization because of unique patho-physiological and surgical factors. The operation, by necessity, disrupts the afferent pathway of the baroreflex, which can lead to postendarterectomy HI. Poor arterial pressure control is associated with increased morbidity and mortality after carotid revascularization, but good control of arterial pressure is often difficult to achieve in practice. The incidence, implications, and etiology of HI associated with carotid surgery are reviewed, and some recommendations made for its management. Close monitoring and titration of therapy are probably the most important considerations rather than specific choice of agents.

Labetalol Infusion Attenuates Paradoxical Hypertension and Decreases Plasma Renin Activity After Repair of Coarctation of the Aorta in Children

OBJECTIVE

Paradoxical hypertension after repair of coarctation of the aorta in children is associated with the release of catecholamines and activation of the renin-angiotensin system. The objective of the present study was to describe the effects of labetalol infusion on blood pressure, plasma catecholamine levels, and plasma renin activity in a series of children undergoing repair of coarctation of the aorta.

DESIGN

Prospective, observational cohort study.

SETTING

Tertiary children's hospital with university affiliation.

PARTICIPANTS

The study was comprised of 15 consecutive children older than 1 year undergoing repair of coarctation of the aorta.

INTERVENTIONS

Intravenous infusion of labetalol, up to 20 µg/kg/min, was administered when patients became hypertensive after release of the aortic cross-clamp. Supplementation with nitroprusside was allowed as needed.

MEASUREMENTS AND MAIN RESULTS

Blood pressure was maintained below baseline values throughout the labetalol infusion. Plasma norepinephrine increased from 160 ± 81 pg/mL (preoperative) to 657 ± 268 pg/mL (6 h after release of aortic cross-clamp). Plasma renin activity decreased from 16.6 ± 9.7 ng/kg/h (at cross-clamp release) to 2.2 ± 2.2 ng/kg/h (6 h after cross-clamp release). Nitroprusside was added for 12 patients, at a highest mean dose of 2.4 ± 2.5 μg/kg/min.

CONCLUSIONS

Labetalol inhibited activation of the renin-angiotensin system and helped control paradoxical hypertension after coarctation repair in children.

Treatment of toxicity from amphetamines, related derivatives, and analogues: a systematic clinical review

BACKGROUND

Overdose of amphetamine, related derivatives, and analogues (ARDA) continues to be a serious worldwide health problem. Patients frequently present to the hospital and require treatment for agitation, psychosis, and hyperadrenegic symptoms leading to pathologic sequelae and mortality.

OBJECTIVE

To review the pharmacologic treatment of agitation, psychosis, and the hyperadrenergic state resulting from ARDA toxicity.

METHODS

MEDLINE, PsycINFO, and the Cochrane Library were searched from inception to September 2014. Articles on pharmacologic treatment of ARDA-induced agitation, psychosis, and hyperadrenergic symptoms were selected. Evidence was graded using Oxford CEBM. Treatment recommendations were compared to current ACCF/AHA guidelines.

RESULTS

The search resulted in 6082 articles with 81 eligible treatment involving 835 human subjects. There were 6 high-quality studies supporting the use of antipsychotics and benzodiazepines for control of agitation and psychosis. There were several case reports detailing the successful use of dexmedetomidine for this indication. There were 9 high-quality studies reporting the overall safety and efficacy of β-blockers for control of hypertension and tachycardia associated with ARDA. There were 3 high-quality studies of calcium channel blockers. There were 2 level I studies of α-blockers and a small number of case reports for nitric oxide-mediated vasodilators.

CONCLUSIONS

High-quality evidence for pharmacologic treatment of overdose from ARDA is limited but can help guide management of acute agitation, psychosis, tachycardia, and hypertension. The use of butyrophenone and later-generation antipsychotics, benzodiazepines, and β-blockers is recommended based on existing evidence. Future randomized prospective trials are needed to evaluate new agents and further define treatment of these patients.

Comparison of Catecholamine Hormone Release in Patients Undergoing Carotid Artery Stenting or Carotid Endarterectomy

PURPOSE

To investigate the pattern of catecholamine response in patients undergoing carotid endarterectomy (CEA) or carotid artery stenting (CAS).

METHODS

Adrenaline, noradrenaline, and renin levels were measured at 5 time points in 12 patients undergoing 13 CEAs (1 bilateral) and 13 patients undergoing unilateral CAS. Arterial blood samples were taken at the following time points: (1) after induction in CEA patients or 5 minutes following first contrast injection in CAS patients, (2) 5 minutes following ICA clamp release in surgical patients or deflation of the balloon in the CAS cohort, (3) 60 minutes following ICA clamp release in surgical patients or deflation of the balloon in the CAS cohort, and (4) 24 hours following the procedure. Intraoperative blood pressure and heart rate were recorded using radial arterial monitoring. Changes in adrenaline, noradrenaline, and renin levels are expressed as ratios versus baseline.

RESULTS

Patterns of adrenaline and noradrenaline release were significantly different in patients undergoing CAS and CEA, with much higher and more variable surges of adrenaline and noradrenaline occurring in CEA patients. Adrenaline and noradrenaline levels increased significantly over baseline following carotid artery clamping in patients undergoing CEA (noradrenaline ratio before clamping: 1.54+/-1.25, 24 hours after unclamping: 8.38+/-16.35 [p<0.001]; adrenaline ratio before clamping: 1.12+/-0.49, 60 minutes after unclamping: 17.59+/-19.14 [p<0.001]). Conversely, in patients undergoing CAS, catecholamine levels remained unchanged (noradrenaline ratio before dilation: 0.96+/-0.23, 24 hours after the procedure: 0.92+/-0.32 [p=NS]; adrenaline ratio before dilation: 0.83+/-0.33, 60 minutes after balloon deflation: 0.56+/-0.32 [p=NS]).

CONCLUSIONS

CAS is associated with a significantly less marked catecholamine response than CEA, which may reflect down-regulation of the sympathetic nervous system in response to carotid sinus stimulation during carotid angioplasty.

Hypertensive encephalopathy after bilateral carotid endarterectomy

BACKGROUND

Hypertension occurs frequently after carotid endarterectomy and may lead to cerebral vascular complications and myocardial infarction. Its pathophysiology has recently been related to surgically induced damage of carotid baroreceptors.

CASE DESCRIPTION

A 45-year-old normotensive man with no history of epilepsy was admitted 3 weeks after bilateral carotid endarterectomy for severe repetitive paroxysmal headaches, vomiting, and agitation that were closely associated with attacks of marked hypertension. During one of these attacks, he had a grand mal seizure. Plasma catecholamine levels during hypertensive attacks were highly elevated despite the absence of pheochromocytoma, reflecting abnormalities in baroreceptor sensitivity that lead to unrestrained activation of the central sympathetic nervous system. Heart rate response to Valsalva maneuver showed suppression of the usual tachycardia, indicating baroreceptor reflex insensitivity.

CONCLUSIONS

We report the first case of hypertensive encephalopathy associated with baroreflex failure syndrome after bilateral carotid endarterectomy. The role of blood pressure monitoring may be critical in revealing carotid baroreceptor insensitivity in such clinical settings.

Fenoldopam infusion for the treatment of postoperative hypertension

STUDY OBJECTIVE

To examine the safety and efficacy of intravenous fenoldopam as compared to placebo for the treatment of postoperative hypertension.

DESIGN

Randomized, placebo-controlled, double-blind study.

SETTING

Community hospital.

PATIENTS

16 ASA I-III hypertensive patients scheduled for noncardiac surgical procedures.

INTERVENTIONS

Treatment with fenoldopam or placebo was initiated immediately after other causes of hypertension had been ruled out. Hypertension was defined as a supine systolic blood pressure (SBP) or diastolic blood pressure (DBP) greater than 20% over the patient's preoperative baseline, which was obtained 6 hours prior to the procedure with the patient lying quietly. The baseline consisted of 3 consecutive blood pressure (BP) measurements obtained at 5-minute intervals and not varying by more than 10%. Fenoldopam or placebo infusion was initiated at 0.1 microgram/kg/min and increased and decreased as necessary until the therapeutic goal BP was reached or treatment failure had occurred. The therapeutic goal BP was a decrease to at least 10% above the preoperative baseline, and failure of treatment was defined as inability to reach this BP level after 15 minutes at 1.5 micrograms/kg/min.

MEASUREMENTS AND MAIN RESULTS

BP and heart rate (HR) data were collected consistently throughout the study and 1 hour after termination of infusion. Laboratory studies and 12-lead electrocardiographic results were obtained at the start of the study and repeated 24 hours after termination of infusion. Blood samples were obtained for the measurement of epinephrine, norepinephrine, and dopamine levels and were analyzed using high-performance liquid chromatography with electrochemical detection. Pretreatment BP measurements were significantly elevated from baseline in both groups. Fenoldopam treatment significantly reduced BP to the therapeutic goal in 8 of 8 patients; placebo reduced BP to this goal in only 4 of 8 patients (p < 0.05). At the end of the titration period, the therapeutic goal BP was not significantly different from baseline in the fenoldopam group. HR was significantly elevated (p < 0.05) at goal in the fenoldopam group as compared with the placebo group. Fenoldopam administration lowered SBP and DBP to goal in a mean time of 28 minutes versus 42.5 minutes in the placebo group. There were no significant differences in catecholamine levels at any of the measurement periods.

CONCLUSION

Fenoldopam is an effective drug for reducing BP following hypertensive episodes in the postoperative setting. Fenoldopam use is associated with an increase in HR versus placebo.

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

Although labetalol (LAB), the combination of an alpha- and beta-adrenergic blocking agent, is thought to be effective and safe for the control of postoperative hypertension, no study has focused on changes in left ventricular (LV) function when this drug was used to control postoperative hypertension. Therefore, this study determined the effects of LAB on hemodynamics and LV function assessed by 2D transesophageal echocardiography (TEE) in 17 patients undergoing abdominal aortic surgery who experienced a postoperative hypertensive episode. Postoperatively, patients were transferred while still intubated and under fentanyl sedation to the postanesthesia care unit where a TEE probe was inserted to provide a short-axis view of the LV. When their systolic blood pressure increased above 165 mmHg for more than 4 minutes, LAB was given in a dose of 0.75 mg/kg IV, over 2 minutes. If the blood pressure was not lowered to within 10% of the preoperative values, additional doses of LAB were given. Control of hypertension was obtained in all patients and was associated with a significant decrease in heart rate (90 +/- 19 to 70 + 13 bpm), cardiac index (4.52 +/- 1.65 to 3.36 +/- 1.55 L/min/m2), and mixed venous oxygen saturation (73 +/- 10 to 63 +/- 10%). With the lower blood pressure, end-diastolic area increased, indicating myocardial depression. In conclusion, LAB can be used to effectively control hypertension during the early postoperative period after abdominal aortic surgery. However, the reduction of blood pressure is achieved principally by the negative inotropic effect of LAB, which predominates over its vasodilator action.