Diagnosis and management of hypertensive emergencies

Management of hypertension in patients during percutaneous dialysis access interventions

Not infrequently, interventionalists are faced with a patient with increased blood pressure who is about to undergo a dialysis access intervention such as tunneled hemodialysis catheter, percutaneous balloon angioplasty, or declotting procedure for a clotted arteriovenous access. This can frequently create a dilemma as functional dialysis access is needed to provide dialysis therapy and delaying treatment could result in a life-threatening situation, particularly in the presence of hyperkalemia. This article investigates hypertension in patients undergoing percutaneous dialysis access interventions and provides guidance to their management.

Hypertensive Urgencies and Emergencies in the Hospital Setting

The prevalence of hypertension in the general population has steadily climbed over the past several decades and hypertension is a primary or secondary diagnosis in nearly a fourth of hospitalized adults. Hospitalization is often a time of pertubation in a patient's usual blood pressure control, with pain, anxiety and missed medications all risk factors for severe hypertension. Hospitalists are often faced with severe hypertension in a patient not previously known to them and this presents a challenge of how best to assess the clinical importance of blood pressure elevation. An additional challenge is the lack of literature to guide the optimal management of hypertension in inpatients. This review aims to describe the scope of the problem, to describe the near and long-term risks of overzealous blood pressure management, and to identify areas for future study.

Blood pressure recordings during hemodialysis access interventions: implications for acute management

A retrospective study evaluating the pattern of blood pressure and its related complications before, during, and after percutaneous hemodialysis interventions was performed in patients presenting with asymptomatic hypertension. Hemodialysis patients undergoing percutaneous interventions including tunneled hemodialysis catheter insertion, percutaneous balloon angioplasty and thrombectomy procedure, and stage II hypertension (systolic blood pressure ≥160 mmHg) were included in this analysis. Blood pressure medications were not used while midazolam and fentanyl were routinely administered. Patients were followed for up to 4 weeks to monitor any complications. The mean blood pressure before, during, and after the procedures were 185 ± 18/96 ± 14, 172 ± 22/92 ± 15, and 153 ± 25/87 ± 14, respectively. There was a statistically significant difference between the blood pressure readings before and after the procedure (before = 185 ± 18/96 ± 14, after = 153 ± 25/87 ± 14; p = 0.001). None of the patients had a stroke, myocardial infarction, or acute pulmonary edema before, during, or after the procedure or during the 4-week follow-up period. A significant reduction in blood pressure was observed after the procedure without the administration of any antihypertensive medication. These results suggest that the reduction in blood pressure observed after percutaneous dialysis access interventions (particularly in the presence of midazolam and fentanyl) may make it unnecessary to treat asymptomatic hypertension prior to these procedures.

Clonidine Lowers Blood Pressure by Reducing Vascular Resistance and Cardiac Output in Young, Healthy Males

PURPOSE

Clonidine is a classical sympatholytic drug that is widely used for the treatment of hypertension. Experimental and clinical studies suggest that Clonidine may activate baroreflex. The aim of this study was to determine the hemodynamic response to Clonidine under physiological conditions and to test the hypothesis that Clonidine would reduce cardiac output and blood pressure resulting in an increase in total peripheral resistance.

METHODS

Clonidine's hemodynamic effect was evaluated in 28 young, healthy subjects after a single i.v. dose of 1 microg x kg(- 1). Impedance cardiography, systolic time intervals and pulse wave analysis were used to characterize myocardial and vascular function.

RESULTS

Clonidine lowered blood pressure, heart rate, left ventricular ejection time, and pulse wave velocity and increased pre-ejection period. Stroke volume and cardiac output decreased gradually over the investigation time of 240 min. Central systolic blood pressure (SBP) was lowered to a larger extent than peripheral SBP. Total peripheral resistance was characterized by an immediate fall of short duration followed by a continuous rise above baseline after 120 min. Placebo did not have any significant effect on hemodynamic parameters.

CONCLUSIONS

Clonidine's blood pressure lowering effect is mediated by both an immediate decrease in vascular resistance and a prolonged decrease in cardiac output, and Clonidine lowers central SBP more than peripheral SBP.