Comparison of nicardipine and sodium nitroprusside in the treatment of paroxysmal hypertension following aortocoronary bypass surgery

A randomized controlled trial: Comparing blood pressure reduction in hyperacute phase of spontaneous intracerebral hemorrhage by continuous nicardipine infusion with or without a preceding nicardipine bolus dose

Objectives

To determine whether addition of an intravenous bolus dose before continuous nicardipine infusion would improve blood pressure reduction in the hyperacute phase in patients with spontaneous intracerebral hemorrhage (ICH).

Design

Double-blind randomized controlled trial.

Setting

One academic emergency department (ED) in Bangkok, Thailand.

Participants

Adult patients with spontaneous ICH presented to the ED between June 30, 2022, and July 15, 2023.

Interventions

The bolus group (n = 31) received an intravenous bolus dose of nicardipine before nicardipine continuous infusion, whereas the non-bolus group (n = 31) was given a placebo and nicardipine continuous infusion.

Main outcomes

Systolic blood pressure (SBP) within the first hour (being measured every 5 min), neurological deterioration, and infusion dosage at 60 min were assessed.

Results

Basic characteristic features including the mean baseline SBP were not significantly different between the two groups. At 10 min after treatment initiation, the bolus group had a significant decrease in SBP (32.1 ± 13.6 vs 22.3 ± 18.5 mmHg; p-value = 0.020). Moreover, the target SBP of 180 mmHg could be achieved within 10 min in the bolus group compared with 15 min in the non-bolus group. However, the overall mean SBPs were not significantly different, with 152 ± 12 mmHg in the bolus group compared with 150 ± 15 mmHg in the non-bolus group (p-value = 0.564). None of the patients in both groups had neurological deterioration over the first hour of the treatment. The infusion dosages of nicardipine at 1 h were 6.2 mg/h (5.9, 7.7 mg/h) and 6.8 mg/h (5.9, 8.4 mg/h) in the bolus and non-bolus groups, respectively (p-value = 0.618).

Conclusions

Administering a 1-mg bolus dose of nicardipine before continuous nicardipine infusion notably reduces SBP at 10 min. However, the overall SBP does not exhibit a significant decline during the hyperacute phase of spontaneous intracerebral hemorrhage.

Calcium Channel Blockers in Acute Care: The Links and Missing Links Between Hemodynamic Effects and Outcome Evidence

Calcium channel blockers (CCBs) exert profound hemodynamic effects via blockage of calcium flux through voltage-gated calcium channels. CCBs are widely used in acute care to treat concerning, debilitating, or life-threatening hemodynamic changes in many patients. The overall literature suggests that, for systemic hemodynamics, although CCBs decrease blood pressure, they normally increase cardiac output; for regional hemodynamics, although they impair pressure autoregulation, they normally increase organ blood flow and tissue oxygenation. In acute care, CCBs exert therapeutic efficacy or improve outcomes in patients with aneurysmal subarachnoid hemorrhage, acute myocardial infarction and unstable angina, hypertensive crisis, perioperative hypertension, and atrial tachyarrhythmia. However, despite the clear links, there are missing links between the known hemodynamic effects and the reported outcome evidence, suggesting that further studies are needed for clarification. In this narrative review, we aim to discuss the hemodynamic effects and outcome evidence for CCBs, the links and missing links between these two domains, and the directions that merit future investigations.

Sodium nitroprusside versus nicardipine for hypertension management after surgery: A systematic review and meta-analysis

BACKGROUND

Vasoactive medications are commonly administered for afterload reduction and arterial hypertension treatment in patients after cardiac surgery. A systematic review and meta-analysis were conducted to determine the effects of sodium nitroprusside and nicardipine on hemodynamics and cardiac performance in this population.

METHODS

A systematic review of published manuscripts was performed to identify studies of patients who received sodium nitroprusside and nicardipine as part of the treatment for arterial hypertension or afterload reduction after cardiac surgery. A meta-analysis was then conducted to determine the effects of sodium nitroprusside and nicardipine on hemodynamics and cardiac performance. The following parameters were captured: blood pressure, heart rate, right atrial pressure, systemic vascular resistance, and stroke volume.

RESULTS

In total, five studies with 571 patients were pooled for these analyses. Systolic blood pressure, diastolic blood pressure, and mean arterial blood pressure were similar in both groups. The cardiac index was greater with nicardipine while mean pulmonary artery pressure was lower with sodium nitroprusside.

CONCLUSION

Nicardipine and sodium nitroprusside have similar abilities in reducing afterload in the postoperative cardiac population. Statistically significant differences were found in pulmonary artery pressure and cardiac index. It may be beneficial to consider nicardipine for afterload reduction in patients with a low cardiac index.

Hyperinflation of Nitroprusside

Sodium nitroprusside (SNP) is a generically available and rapid-acting intravenous (IV) vasodilator that has been used clinically for decades. Prior to 2013, the cost of SNP was relatively low, and SNP was an affordable option for the treatment of acute hypertension. However, from 2013 to 2017, average wholesale prices for SNP rose to as high as $900 per vial, earning the drug its status as a "hyperinflation drug." Hyperinflation drugs such as SNP pose a significant challenge for pharmacy departments. A multidisciplinary effort involving stakeholders from many backgrounds, including pharmacists, physicians, and nurses, is key to developing an effective plan to address the problem. A therapeutic interchange, wherein a drug with similar efficacy is substituted for another, is often an appropriate strategy in this scenario. Fortunately, alternative drugs with a solid evidence base exist for the management of acute hypertension. The dihydropyridine calcium channel blockers, clevidipine and nicardipine, are IV titratable antihypertensive agents with favorable pharmacokinetic and safety profiles. Various studies indicate that clevidipine and nicardipine are effective alternatives to SNP for indications including hypertensive crisis and postoperative hypertension. Some hospitals have reported significant cost savings without adverse outcomes by substituting clevidipine or nicardipine for SNP. This article is intended to serve as a review of the evidence for clevidipine and nicardipine as potential substitutes for SNP and to provide strategies to successfully implement this therapeutic interchange.

Sodium Nitroprusside as a Hyperinflation Drug and Therapeutic Alternatives

Sodium nitroprusside (SNP) is a generically available and rapid-acting intravenous (IV) vasodilator that has been used clinically for decades. Prior to 2013, the cost of SNP was relatively low, and SNP was an affordable option for the treatment of acute hypertension. However, from 2013 to 2017, average wholesale prices for SNP rose to as high as US$900 per vial, earning the drug its status as a "hyperinflation drug." Hyperinflation drugs pose a significant challenge for pharmacy departments. A multidisciplinary effort involving stakeholders from many backgrounds, including pharmacists, physicians, and nurses, is key to developing an effective cost containment strategy. A therapeutic interchange, wherein a drug with similar efficacy is substituted for another, is often an appropriate strategy to address rising drug costs. Fortunately, alternative drugs with a solid evidence base exist for the management of acute hypertension. The dihydropyridine calcium channel blockers, clevidipine and nicardipine, are IV titratable antihypertensive agents with favorable pharmacokinetic and safety profiles. Various studies indicate that clevidipine and nicardipine are effective alternatives to SNP for indications including hypertensive crisis and postoperative hypertension. Some hospitals have reported significant cost savings without adverse outcomes by substituting clevidipine or nicardipine for SNP. This article is intended to serve as a review of the evidence for clevidipine and nicardipine as potential substitutes for SNP and to provide strategies to successfully implement this therapeutic interchange.

Postoperative Critical Care of the Adult Cardiac Surgical Patient. Part I: Routine Postoperative Care

OBJECTIVES

Cardiac surgery, including coronary artery bypass, cardiac valve, and aortic procedures, is among the most common surgical procedures performed in the United States. Successful outcomes after cardiac surgery depend on optimum postoperative critical care. The cardiac intensivist must have a comprehensive understanding of cardiopulmonary physiology and the sequelae of cardiopulmonary bypass. In this concise review, targeted at intensivists and surgeons, we discuss the routine management of the postoperative cardiac surgical patient.

DATA SOURCE AND SYNTHESIS

Narrative review of relevant English-language peer-reviewed medical literature.

CONCLUSIONS

Critical care of the cardiac surgical patient is a complex and dynamic endeavor. Adequate fluid resuscitation, appropriate inotropic support, attention to rewarming, and ventilator management are key components. Patient safety is enhanced by experienced personnel, a structured handover between the operating room and ICU teams, and appropriate transfusion strategies.

Nicardipine versus Sodium Nitroprusside for Postcardiac Surgery Hypertension: An Evaluation of Effectiveness and Postoperative Costs

Background

Postoperative hypertension after cardiac surgery is associated with substantial morbidity. Both sodium nitroprusside (SNP) and nicardipine (NIC) are effective in its management. Outcomes data for NIC and SNP in persons undergoing cardiac surgery are limited, and there are no data characterizing the influence of drug choice on postoperative costs.

Objective

Our aim was to compare the effectiveness of NIC versus SNP in the management of hypertension after cardiac surgery and evaluate the influence of drug choice on postoperative costs.

Methods

We conducted a retrospective, cohort study using our hospital's financial and electronic medical records. Adults admitted to a cardiothoracic surgical intensive care unit after coronary artery bypass grafting (CABG) and/or valve surgery who developed hypertension requiring ≥30 minutes of NIC or SNP were included. We evaluated drug effectiveness by assessing infusion rate stability, blood pressure and heart rate, and concomitant antihypertensive agent use. Activity-based postoperative costs were compared between study groups.

Results

One hundred twelve subjects were included (NIC = 72, SNP = 40). Hypertension-related demographics were balanced between the groups. NIC was associated with improved infusion rate stability that required fewer dose changes per hour (1.2 ± 1.6) versus SNP (1.7 ± 1.8) ( P = .004). Heart rates and blood pressures did not differ significantly. The number of antihypertensive medications used before and during the NIC or SNP infusions was the same. However, persons who were prescribed SNP required significantly more medications to manage blood pressure after infusions were discontinued ( P = .001). NIC use did not significantly increase postoperative cost. NIC use may be associated with cost increases in isolated CABG but with cost savings in isolated valve or combined CABG/valve surgeries; however, these differences were not statistically significant.

Conclusions

Blood pressure was equally controlled using NIC or SNP. NIC was associated with improved infusion rate stability. Despite a higher acquisition cost, NIC did not significantly influence postoperative costs. Larger, prospective cost-effective analyses in surgical subgroups are needed.

Acute kidney injury following cardiac surgery: role of perioperative blood pressure control

BACKGROUND/AIMS

Patients who develop acute kidney injury (AKI) after cardiac surgery continue to have a high mortality rate. Although factors that predispose to postoperative renal dysfunction have been identified, this knowledge has not been associated with a substantial reduction in the incidence of this serious adverse event.

METHODS

This review uses the existing literature to explore the relationship between AKI and perioperative blood pressure (BP) control in cardiac surgery patients. The results of recent novel analyses are introduced, and the implications of these studies for the management of cardiac surgery patients in the perioperative period are discussed.

RESULTS

Preexisting isolated systolic hypertension and wide pulse pressure increase the risk of postoperative renal dysfunction in the cardiac surgery population. New data suggest that BP lability (i.e., BP excursions outside an acceptable physiologic range) during cardiac surgery may also be an important predictor of subsequent renal dysfunction.

CONCLUSION

Recently published data suggest that perioperative BP lability influences both the risk of postoperative renal dysfunction and 30-day mortality. Future studies will determine whether the use of agents that allow improved BP control within a desirable range will reduce the incidence of postoperative AKI in cardiac surgery patients.

Perioperative hypertension: a review of current and emerging therapeutic agents

Perioperative hypertension is a common problem encountered by anesthesiologists, surgeons, internists, and intensivists. Surprisingly, no randomized, placebo-controlled studies exist that show that the treatment of perioperative hypertension reduces morbidity or mortality. Nevertheless, perioperative hypertension requires careful management. While sodium nitroprusside and nitroglycerin are commonly used to treat these conditions, these agents are less than ideal. Intravenous beta blockers and calcium channel blockers have particular appeal in this setting.

PROSPECTIVE RANDOMIZED COMPARISON OF SAFETY AND EFFICACY OF NICARDIPINE AND NITROPRUSSIDE DRIP FOR CONTROL OF HYPERTENSION IN THE NEUROSURGICAL INTENSIVE CARE UNIT

OBJECTIVE

The calcium channel blocker nicardipine (NC) is effective for acute control of hypertension. However, efficacy and safety in neurosurgical patients have not been evaluated. We sought to compare NC with the most commonly used agent, sodium nitroprusside (SNP), in patients with subarachnoid or intracerebral hemorrhage.

METHODS

We performed a prospective randomized comparison of the safety and efficacy of NC and SNP in patients with subarachnoid or intracerebral hemorrhage. We assessed the number of dose adjustments per patient day, proportion of time within set blood pressure parameters, use of additional medications for blood pressure control, clinical outcome, and drug-related complications.

RESULTS

Two hundred patients were screened and 163 patients were randomized, including 89 in the SNP group and 74 in the NC group. In 107 patients, intravenous blood pressure control was started; 60 of these patients received SNP and 47 received NC. When analyzed by intent to treat, patients randomized to NC had fewer dose adjustments per day: 5.7 versus 8.8 in the nitroprusside group (P = 0.0012, Wilcoxon rank-sum test). There were fewer additional medications per day to maintain blood pressure control in the NC group: 1.4 versus 1.9 for SNP (P = 0.043, Wilcoxon rank-sum test). Blood pressure control was similar (NC, 66% of the time within parameters; SNP, 69%). “As-treated” analysis maintained the apparent advantage of NC.

CONCLUSION

When used for control of hypertension in patients with subarachnoid or intracerebral hemorrhage, NC and SNP were both safe and effective, but patients on an NC drip required fewer dose adjustments and fewer additional medications.

Intravenous Nicardipine

Nicardipine is a water soluble calcium channel antagonist, with predominantly vasodilatory actions. Intravenous (IV) nicardipine (Cardene IV), which demonstrates a relatively rapid onset/offset of action, is used in situations requiring the rapid control of blood pressure (BP). IV nicardipine was as effective as IV nitroprusside in the short-term reduction of BP in patients with severe or postoperative hypertension. A potential role for IV nicardipine in the intraoperative acute control of BP in patients undergoing various surgical procedures (including cardiovascular, neurovascular and abdominal surgery), and in the deliberate induction of reduced BP in surgical procedures in which haemostasis may be difficult (e.g. surgery involving the hip or spine) was demonstrated in preliminary studies. Preliminary studies also indicated the ability of a bolus dose of IV nicardipine to attenuate the hypertensive response, but not the increase in tachycardia, after laryngoscopy and tracheal intubation in anaesthetised patients. In large, well designed studies, IV nicardipine prevented cerebral vasospasm in patients with recent aneurysmal subarachnoid haemorrhage; however, overall clinical outcomes at 3 months were similar to those in patients who received standard management. Small preliminary studies have investigated the use of IV nicardipine in a variety of other settings, including acute intracerebral haemorrhage, acute ischaemic stroke, pre-eclampsia, acute aortic dissection, premature labour and electroconvulsive therapy.In conclusion, the efficacy of IV nicardipine in the short-term treatment of hypertension in settings for which oral therapy is not feasible or not desirable is well established. The ability to titrate IV nicardipine to the tolerance levels of individual patients makes this agent an attractive option, especially in critically ill patients or those undergoing surgery. Potential exists for further investigation of the use of this agent in clinical settings where a vasodilatory agent with minimal inotropic effects is appropriate.

Comparison of the Effects of Nicardipine and Sodium Nitroprusside for Control of Increased Blood Pressure after Coronary Artery Bypass Graft Surgery

We compared the haemodynamic effects of nicardipine and sodium nitroprusside after coronary artery bypass graft surgery. When post-surgery systolic blood pressure reached > 150 mmHg, patients were randomly given nicardipine (N group, n = 26) or sodium nitroprusside (S group, n = 21). The drugs were infused at a rate of 2 μg/kg per min for 10 min. If the target blood pressure (120-140 mmHg) was not achieved, the infusion rate was increased by 1 üg/kg per min every 10 min. Cardiac and stroke volume indices had increased significantly in the N group after 10 min and in both groups after 60 min. The infusion duration and total dose of drug were significantly lower in the N group compared with the S group. Nicardipine infusion controlled post-operative hypertension more rapidly and was superior to sodium nitroprusside in maintaining left ventricular performance immediately after drug infusion.

Nicardipine versus Nitroprusside Infusion as Antihypertensive Therapy in Hypertensive Emergencies

This prospective study compared the efficacy of nicardipine and nitroprusside for treating hypertensive emergencies by measuring haemodynamic indices and serum catecholamine levels. Patients admitted to the emergency department with a hypertensive crisis and acute pulmonary oedema received intravenous infusions of nitroprusside (starting dose 1 μg/kg per min, n = 20) or nicardipine (starting dose 3 μg/kg per min, n = 20). Both groups experienced significant declines in systolic and diastolic blood pressure after treatment, but there were no significant time-dependent differences between the groups. Heart rate decreased in the nicardipine group and increased in the nitroprusside group, but neither change was significant. Respiration rate decreased and capillary oxygen saturation rate increased after treatment in both groups. Adrenaline and noradrenaline levels decreased significantly after treatment in both groups; noradrenaline levels were significantly decreased in the nicardipine-treated group compared with the nitroprusside-treated group. Injectable nicardipine is easy to use and as effective as nitroprusside for treating hypertensive crisis with acute pulmonary oedema.

Calcium antagonists reduce cardiovascular complications after cardiac surgery: a meta-analysis

OBJECTIVES

We sought to determine the efficacy of calcium antagonists (CAs) in reducing death, myocardial infarction (MI), ischemia, and supraventricular tachyarrhythmia (SVT) after cardiac surgery.

BACKGROUND

Calcium antagonists may reduce complications after cardiac surgery-namely, death, MI, and renal failure. However, they are underused, possibly due to the results from previous observational studies.

METHODS

Both MEDLINE (1966 to December 2001) and EMBASE (1980 to December 2001) were searched, with supplementation by reference list searches. No language restrictions were applied. Included studies were randomized, controlled trials (RCTs) evaluating preoperative, intraoperative, or postoperative (first 48 h) CA use (intravenous or oral) during aortocoronary bypass or valve surgery. Studies were excluded if they exclusively recruited transplant recipients, individuals <18 years old, or patients with pre-existing SVT. Two reviewers independently evaluated study quality by using the Jadad score; a minimal score of 1/5 was required. Forty-one studies, encompassing 3,327 patients, were included. No studies assessed treatment exclusively with short-acting oral nifedipine. Treatment effects were calculated using the random-effects model. Heterogeneity was assessed using the Q test.

RESULTS

Calcium antagonists significantly reduced MI (odds ratio [OR] 0.58, 95% confidence interval [CI] 0.37 to 0.91; p = 0.02) and ischemia (OR 0.53, 95% CI 0.39 to 0.72; p < 0.001). Non-dihydropyridines significantly reduced SVT (OR 0.62, 95% CI 0.41 to 0.93; p = 0.02). Calcium antagonists were associated with trends toward decreased mortality during aortocoronary bypass (OR 0.66, 95% CI 0.26 to 1.70, p = 0.4).

CONCLUSIONS

Use of CAs during cardiac surgery significantly reduced rates of MI, ischemia, and SVT. Further study using large RCTs is justified.

Comprehensive management of hypertensive emergencies and urgencies

Despite advances in chronic hypertension management, hypertensive emergencies and urgencies remain as serious complications. Much of this relates to poor compliance with effective antihypertensive management. Hypertensive emergencies and urgencies can also be seen as the initial manifestations of hypertension in pregnancy and in the perioperative period. Multiple classes of intravenous antihypertensive drugs are available to treat hypertensive emergencies, and specific agents may have an advantage in a given clinical situation. Orally active agents are used to treat hypertensive urgencies, and include clonidine, angiotensin-converting enzyme inhibitors, and labetalol. Most patients respond to drug therapy, but problems may arise related to a rapid normalization of blood pressure.

[Comparison of nicardipine and isradipine in hypertension following coronary artery bypass graft]

OBJECTIVE

Compare the efficacy of isradipine to that of nicardipine for the control of arterial hypertension following coronary artery bypass graft (CABG).

STUDY DESIGN

Clinical prospective, randomised study.

MATERIAL AND METHODS

40 patients ASA II or III, mean age 66 +/- 8 years, scheduled for elective CABG were included. If the mean arterial pressure (MAP) was > or = 100 mmHg within the first six post operative hours, the patients were included and randomly attributed to either one of the 2 groups: Gr I (n = 20) received nicardipine, Gr II (n = 20) received isradipine in bolus then in continuous perfusion. HR, MAP, MPAP, CVP, PCWP, CI, SVRI, PVRI and SVI were recorded at: T0 before administration of drugs, T1 = 2 min after the first bolus. T2 when MAP reached 85 +/- 5 mmHg. T3, T4, T5, T6, T7 and T8 at 5, 10, 30, 60, 90 and 120 min after the continuous perfusion. T9 before stopping the perfusion.

RESULTS

No significant changes in HR, CVP, PCWP, MPAP or PVRI at any time in both groups. Significant increase in CI at T2 in both groups. Reduction of MAP at T2 was more important (-27%) in Gr I compared to that in Gr II (-22%). This was mainly due to a significant decrease in SVRI.

CONCLUSION

Isradipine is effective in the treatment of arterial hypertension following CABG. However there is not any significant beneficial effect of isradipine over nicardipine.

Nicardipine to control mean arterial pressure after cardiothoracic surgery in infants and children

Nicardipine is the first intravenously administered dihydropyridine calcium channel blocker. Its primary physiologic action includes vasodilatation with limited effects on the inotropic and dromotropic function of the myocardium. Several previous reports document its use in adult patients for pharmacologic control of blood pressure. The current report describes the use of nicardipine to control mean arterial pressure (MAP) in nine infants and children after cardiothoracic surgical procedures. The patients ranged in age from 6 days to 9 years (mean, 3.3 +/- 4.1 years) and in weight from 4.1 to 49 kg (mean, 15.3 +/- 14.4). The surgical procedures included aortic coarctation repair (three), repair of tetralogy of Fallot (two), arterial switch for transposition of the great vessels (two), pulmonary valvotomy (one), and aortic valvotomy (one). The target systolic blood pressure was 90 mm Hg in patients younger than 4 years of age and < or = 110 mm Hg in patients 5 years of age or older. The nicardipine infusion was started at 5 microg/kg/min in all patients. The target blood pressure was achieved within 15 minutes in eight of nine patients. One patient required an initial infusion rate of 10 microg/kg/min to achieve the target blood pressure. The maintenance infusion rate varied from 2.5 to 5.5 mcg/k/min (mean 3.0 +/- 1.1). The duration of the infusion varied from 30 to 42 hours (mean, 37.4 +/- 4.2). In the nine patients, nicardipine was infused for a total of 337 hours. No adverse effects such as excessive hypotension were noted. Nicardipine is an effective agent for controlling MAP after cardiothoracic surgical procedures in infants and children.

Perioperative anesthetic management of the kidney-pancreas transplant recipient

Patients undergoing simultaneous pancreas-kidney transplantation are at risk for a variety of serious perioperative complications. These are related to the chronic and acute problems associated with end-stage renal disease and insulin-dependent diabetes mellitus and the prolonged, vascular and ductal surgery required to implant the two allografts. A number of strategies need to be integrated and diligently implemented to minimize the physiologic perturbations and complications related to the recipient's comorbid conditions and revascularization of the allografts. A major objective of the perioperative anesthetic management of simultaneous pancreas-kidney transplantation is to maximize cardiovascular performance in a way that provides optimum graft perfusion and recovery, while avoiding myocardial ischemia. Adherence to this objective, along with very effective immunosuppressants, surgical refinements, meticulous anesthetic preparation, extensive and frequent physiologic and metabolic monitoring, and quick response to abnormal findings has resulted in remarkably low recipient morbidity and mortality, and very high graft survival rates.

Coronary and systemic hemodynamic effects of clevidipine, an ultra-short-acting calcium antagonist, for treatment of hypertension after coronary artery surgery

BACKGROUND

The aim was to evaluate the use of clevidipine, a new vascular selective, ultra-short-acting calcium antagonist for blood pressure control after coronary artery bypass grafting (CABG).

METHODS

The effects of clevidipine on central hemodynamics, myocardial blood flow and metabolism were studied at two different phases after CABG. In phase 1 (n=13), the hypertensive phase, the effects of clevidipine were compared to those of sodium nitroprusside (SNP) when used to control postoperative hypertension. In phase 2 (n=9), the normotensive phase, a clevidipine dose-response relationship was established.

RESULTS

At a target mean arterial pressure (MAP) of 75 mmHg, systemic vascular resistance (SVR) and heart rate (HR) were lower, preload, stroke volume (SV) and pulmonary vascular resistance (PVR) were higher, while there were no differences in myocardial lactate metabolism or oxygen extraction with clevidipine compared to SNP. In the normotensive phase, clevidipine induced a dose-dependent decrease in MAP (-19%), SVR (-27%) and PVR (-15%), accompanied by an increase in SV (10%), but no reflex increase in HR or changes in cardiac preload. Clevidipine caused a direct coronary vasodilation, as indicated by a decrease in myocardial oxygen extraction from 54% to 45%. Myocardial lactate metabolism was unaffected by clevidipine. The blood clearance of clevidipine was 0.05 l x min(-1) x kg(-1), the volume of distribution at steady state was 0.08 l x kg(-1) and the initial and terminal half-lives were <1 min and 4 min, respectively.

CONCLUSIONS

Clevidipine rapidly reduced MAP and induced a systemic, pulmonary and coronary vasodilation with no effect on venous capacitance vessels or HR. Clevidipine caused no adverse effects on myocardial lactate metabolism. Clevidipine thus appears suitable to control blood pressure after CABG.

Treatment of hypertension in the perioperative patient

OBJECTIVE

To review studies and drug therapy relating to the treatment of hypertension in perioperative patients.

DATA SOURCES

Articles were selected from a MEDLINE search (1966-August 1998), and several textbooks on hypertension and surgery were reviewed. In addition, bibliographies of all articles and textbook chapters were studied for articles not found in the computerized searches.

STUDY SELECTION

Clinical studies involving hypertension in the perioperative setting were included. The initial search was limited to studies conducted in humans and published in English.

DATA EXTRACTION

Information regarding drug therapy was reviewed and guidelines were constructed for managing surgical patients with acute blood pressure elevations.

DATA SYNTHESIS

Although nitroprusside and nitroglycerin, with their short onset of action and duration of effect, are indicated for hypertensive emergencies, a variety of agents are available for hypertensive urgencies. An algorithm that can be used as a template for the development of intrainstitutional guidelines is provided.

CONCLUSIONS

Due to the scarcity of comparative trials, decisions involving agents for the treatment of perioperative hypertension must often be made based on combined efficacy, toxicity, cost, and convenience considerations.

Effects of nicardipine and nitroglycerin on perioperative myocardial ischemia in patients undergoing coronary artery bypass surgery

Perioperative myocardial ischemic episodes are predictive of adverse cardiac outcomes after coronary artery bypass surgery. We compared the efficacy of continuous infusions of nicardipine (group NIC) and nitroglycerin (group NTG) in reducing the frequency and severity of myocardial ischemic episodes. Patients received either a nicardipine infusion, 0.7 to 1.4 microg/kg/min (n = 30), nitroglycerin infusion, 0.5 to 1 microg/kg/min (n = 30), or neither medication (group C; n = 17) after aortic occlusion clamp release and for 24 hours postoperatively. Myocardial ischemic episodes were considered as ST segment depressions or elevations of 1 mm or greater from baseline, each at J + 60 milliseconds and lasting 1 minute or greater, using a two-channel Holter monitor. Only nicardipine significantly decreased the duration (3.2 +/- 1.2 min/h) and the area under the ST time curve (AUC; 5.7 +/- 15.7 AUC/h) of 1-mm or greater myocardial ischemic episodes compared with group C (17.2 +/- 5.6 min/h and 30.1 +/- 49 AUC/h, respectively) during the intraoperative postbypass period. A trend toward lower frequency, duration, and area under the ST time curve of myocardial ischemic episodes was observed in group NIC compared with group NTG. Cardiac indices and mixed venous oxygen saturations were significantly greater, whereas systemic pressures were less in group NIC compared with group NTG for the same period. These results suggest that nicardipine, but not nitroglycerin, decreased the duration and area under the ST time curve of myocardial ischemic episodes shortly after coronary revascularization. Larger studies are required to verify the efficacy of nicardipine in reducing the severity of myocardial ischemia during cardiac surgery.

A comparison of prostacyclin and sodium nitroprusside for the treatment of heart failure after cardiac surgery

OBJECTIVE

To study the effects of the two vasodilators, prostacyclin and sodium nitroprusside, on central hemodynamics in heart failure after cardiac surgery.

DESIGN

Randomized cross-over study.

SETTING

Multi-institutional university hospital.

PARTICIPANTS

Ten patients.

INCLUSION CRITERIA

cardiac index less than 2.5 L/min/m2; pulmonary capillary wedge pressure greater than 15 mmHg, systemic vascular resistance index greater than 2,500 dynes.s.cm-5/m2, and treatment with inotropic support. Five patients were treated with intra-aortic balloon counterpulsation.

INTERVENTIONS

After control measurements, mean arterial pressure was decreased by 10% to 20% with each vasodilator in each patient.

MEASUREMENTS AND RESULTS

Sodium nitroprusside induced decreases in mean pulmonary arterial pressure (-21%), pulmonary capillary wedge pressure (-29%), central venous pressure (-17%), and systemic vascular resistance (-25%), and increases in cardiac output (+7%) and stroke volume (+6%) compared with control. Prostacyclin decreased mean pulmonary arterial pressure (-14%), pulmonary capillary wedge pressure (-19%), central venous pressure (-7%), and systemic (-40%) and pulmonary (-25%) vascular resistances, whereas cardiac output (+25%) and stroke volume (+22%) increased compared with control. Prostacyclin, compared with sodium nitroprusside, induced a more pronounced increase in cardiac output and stroke volume, associated with less pronounced decreases in cardiac filling pressures and more profound decreases in systemic and pulmonary vascular resistances.

CONCLUSION

Prostacyclin appears to be a useful agent, superior to sodium nitroprusside, in the treatment of postoperative heart failure in patients with normal or mildly elevated cardiac filling pressures, where vasodilator treatment is indicated.

Management of hypertensive urgencies and emergencies

Hypertensive emergency is a condition in which there is elevation of both systolic and diastolic blood pressure with the presence of acute target organ disease. Hypertensive urgency is a condition where the blood pressure is elevated (diastolic > 120 mmHg) with the absence of acute target organ disease. Hypertensive emergencies are best managed with parenteral drugs and careful intraarterial blood pressure monitoring. Hydralazine has been widely used in treatment of hypertension in eclampsia and preeclampsia, and its safety has been demonstrated in these patients. Sodium nitroprusside (SNP) has the most reliable antihypertensive activity, which begins immediately after its administration and ends when the infusion is stopped. As with diazoxide, it should be used with caution in patients with impaired cerebral flow. SNP is the preferred drug in obtaining controlled hypotension in patients undergoing neurovascular surgery. Intravenous nitroglycerin is useful in patients prone to myocardial ischemia, but should be avoided in patients with increased intracranial pressure. Esmolol is effective in controlling both supraventricular tachyarrhythmias and severe hypertension. Its short onset of duration of action make it useful in the emergent setting, but because of its negative inotropic effect its use should be avoided in patients with low cardiac output. Verapamil should not be used in patients with preexisting conduction abnormalities. Nicardipine is a potent arteriolar vasodilator without a significant direct depressant effect on myocardium. As with other afterload reducing agents, it should not be used in patients with severe aortic stenosis. Because angiotensin-converting enzyme (ACE) inhibitors generally cause cerebral vasodilatation, enalaprilat may be particularly beneficial for patients who are at high risk of developing cerebral hypotensive episodes secondary to impaired cerebral circulation. Fenoldopam, a selective post-synaptic dopaminergic receptor (DA1) has been shown to be effective in treating severe hypertension with a lower incidence of side effects than SNP. Hypertensive urgencies can usually be managed with oral agents. Oral nifedipine, captopril, clonidine, labetalol, prazosin, and nimodipine have all been shown to be effective in these situations.

Sodium nitroprusside: twenty years and counting

SNP remains an effective, reliable, and commonly used drug for the rapid reduction of significant arterial hypertension regardless of the etiology, for afterload reduction in the face of low CO when blood volume is normal or increased, and for intraoperative induced hypotension. After establishing indwelling arterial monitoring, an initial infusion rate of 0.3-0.5 micrograms.kg-1.min-1 is begun with titration as needed up to 2.0 micrograms.kg-1.min-1. Higher rates for brief periods of time (10 min) are acceptable. The use of alternative drugs to reduce the dose or shorten the duration of infusion should be considered when the 2.0 micrograms.kg-1.min-1 range is exceeded (Table 1). SNP should not be used by individuals unfamiliar with its potency and metabolic pathways, as the many reports of adverse reactions testify. Careful attention to infusion rates, particularly in patients at risk for depleted thiosulfate stores, is mandatory, and the use of other drugs in conjunction with or instead of SNP should always be considered. As with many therapeutic interventions, SNP requires careful administration to appropriately selected patients by a clinician who knows its inherent hazards. Despite its toxicity, SNP is popular because it is often the most (in some cases, the only) effective drug in some difficult clinical circumstances.

Enoximone vs nicardipine during the early postoperative course of patients undergoing cardiac surgery. A prospective study of two therapeutic strategies

The hemodynamic effects of enoximone and nicardipine were compared during the early postcardiac surgery period in 40 patients with systemic hypertension and moderate cardiac dysfunction. Patients were prospectively randomized into two groups. Mean right atrial pressure was maintained above 7 mm Hg. The drug infusion rate was adjusted to maintain mean systemic artery pressure (SAP) within the 65 to 80 mm Hg range. Complete hemodynamic evaluations were performed before any drug infusion and during the following 24 h with special attention to O2-related variables. Oxygen consumption, cardiac index, and stroke index improved significantly and similarly in the two groups. The SAP and systemic vascular resistance decreased more rapidly in the enoximone group but whole body lactate level increased after the second hour of infusion. Furthermore, this was paralleled by an arteriovenous O2 contents difference deficit. In our study, nicardipine was found superior over enoximone in terms of recovery from intraoperative tissue hypoxia. Furthermore, enoximone's inotropic effects were not found to be clinically relevant.

The ideal agent for perioperative hypertension and potential cytoprotective effects

Perioperative hypertension is primarily due to increased systemic vascular resistance (SVR). Therefore, the major therapeutic approaches are directed at reducing vasoconstriction, using drugs that increase cyclic nucleotides or block calcium entry into vascular smooth muscle. Nitroprusside and other nitric oxide-derived vasodilators affect both the resistance vessels and the vascular capacitance bed. Antihypertensive drugs that affect venous return can have unpredictable effects on blood pressure and calculated SVR. The new intravenous dihydropyridine calcium antagonists have arterial vasodilating actions and are especially promising as new therapeutic approaches for perioperative hypertension. Following coronary bypass-grafting, patients have undergone direct mechanical manipulation of their native grafts, coronary arteries, and internal mammary artery, creating a potential risk for coronary or internal mammary spasm. Calcium antagonists may be an important therapy for perioperative hypertension in such patients. Experimental models have demonstrated that calcium antagonists can attenuate the production of inflammatory mediators and thereby reduce cellular damage following reperfusion. These potential anti-inflammatory drugs may prove to offer additional benefits in the therapy of perioperative hypertension. The potential anti-inflammatory and cytoprotective effects of calcium antagonists may make them the ideal agents for the treatment of acute perioperative hypertension.