Successful resuscitation and neurologic recovery from refractory ventricular fibrillation after magnesium sulfate administration

Drugs in Out-of-Hospital Cardiac Arrest

Managing out-of-hospital cardiac arrest involves unique challenges, including delays in the initiation of advanced interventions and a limited number of trained personnel on scene. Recent out-of-hospital randomized controlled trials, systematic reviews, and metaanalyses provide key insights into what interventions are best proven to positively impact patient outcomes from out-of-hospital cardiac arrest. We review the literature on medications used in out-of-hospital cardiac arrest and summarize evidence-based guidelines from the American Heart Association that form the basis for most emergency medical services cardiac arrest protocols across the United States.

Does Intravenous Magnesium Benefit Patients of Cardiac Arrest? a Meta-Analysis

Objective

Evidence shows that magnesium has anti-arrhythmic roles. However, clinical trials suggest that there are conflicting outcomes of cardiac arrest patients given magnesium. The study aimed to examine the effects of magnesium sulfate therapy on cardiac arrest patients using a meta-analysis.

Methods

We searched the MEDLINE (1966-July 2011), OVID (1980-July 2011), EMBASE (1980-July 2011), Chinese bio-medical literature & retrieval system (1978-July 2011), Chinese medical current contents (1995-July 2011), and Chinese medical academic conference (1994-July 2011). Studies were included if (1) the study design was a randomised controlled trial (RCT); (2) the study population included cardiac arrest patients who received cardiopulmonary resuscitation and either intravenous magnesium or placebo (0.9% normal saline); (3) the study provided data on return of spontaneous circulation (ROSC) and survival to hospital discharge. Relative risk (RR) and 95% confidence interval (CI) were used to pool the effect.

Results

The study included six RCTs with a total of 531 participants from cardiac arrest. The pooled data demonstrated that ROSC and hospital discharge rates in patients treated with magnesium were 35.5% (95% CI=29.7%-41.3%) and 10.4% (95% CI=6.7%-14.1%) compared with placebo (ROSC rate: 31.3%, 95% CI=25.8%-36.8%; hospital discharge rate: 8.5%, 95% CI=5.2%-11.8%). Administration of intravenous magnesium sulfate could not significantly increase ROSC (RR=1.14, 95% CI=0.91-1.43, P=0.26) and survival to hospital discharge (RR=1.22, 95% CI=0.74-2.02, P=0.43) compared with placebo.

Conclusions

Administration of magnesium sulfate does not improve ROSC and survival to hospital discharge in patients of cardiac arrest.

The impact of the code drugs: cardioactive medications in cardiac arrest resuscitation

The goal of treating patients who present with cardiac arrest is to intervene as quickly as possible to affect the best possible outcome. The mainstays of these interventions, including early activation of the emergency response team, early initiation of cardiopulmonary resuscitation, and early defibrillation, are essential components with demonstrated positive impact on resuscitation outcomes. Conversely, the use of the code drugs as a component of advanced life support has not benefited these patients to the same extent as the basic interventions in a general. Although short-term outcomes are improved as a function of these medications, the final outcome has not been altered significantly in most instances.

Magnesium disorders in horses

Magnesium (Mg) is an essential macroelement that is required for cellular energy-dependent reactions involving adenosine triphosphate and for the regulation of calcium channel function. Subclinical hypomagnesemia is common in critically ill humans and animals and increases the severity of the systemic inflammatory response syndrome; worsens the systemic response to endotoxins; and can lead to ileus, cardiac arrhythmias, refractory hypokalemia, and hypocalcemia. This article discusses the clinical signs, consequences, and treatment of hypomagnesemia in horses and describes the association of Mg and endotoxemia, insulin resistance, and brain injury.

A randomised trial to investigate the efficacy of magnesium sulphate for refractory ventricular fibrillation

BACKGROUND

Ventricular fibrillation (VF) remains the most salvageable rhythm in patients suffering a cardiopulmonary arrest (CA). However, outcome remains poor if there is no response to initial defibrillation. Some evidence suggests that intravenous magnesium may prove to be an effective antiarrhythmic agent in such circumstances.

STUDY HYPOTHESIS

Intravenous magnesium sulphate given early in the resuscitation phase for patients in refractory VF (VF after 3 DC shocks) or recurring VF will significantly improve their outcome, defined as a return of spontaneous circulation (ROSC) and discharge from hospital alive.

DESIGN

A randomised, double blind, placebo controlled trial. Pre-defined primary and secondary endpoints were ROSC at the scene or in accident and emergency (A&E) and discharge from hospital alive respectively. SETTING, PARTICIPANTS, AND INTERVENTION: Patients in CA with refractory or recurrent VF treated in the prehospital phase by the county emergency medical services and/or in the A&E department. One hundred and five patients with refractory VF were recruited over a 15 month period and randomised to receive either 2-4 g of magnesium sulphate or placebo intravenously.

RESULTS

Fifty two patients received magnesium treatment and 53 received placebo. The two groups were matched for most parameters including sex, response time for arrival at scene and airway interventions. There were no significant differences between magnesium and placebo for ROSC at the scene or A&E (17% v 13%). The 4% difference had 95% confidence intervals (CI) ranging from -10% to +18%. For patients being alive to discharge from hospital (4% v 2%) the difference was 2% (95% CI -7% to +11%). After adjustment for potential confounding variables (age, witnessed arrest, bystander cardiopulmonary resuscitation and system response time), the odds ratio (95% CI) for ROSC in patients treated with magnesium as compared with placebo was 1.69 (0.54 to 5.30).

CONCLUSION

Intravenous magnesium given early in patients suffering CA with refractory or recurrent VF did not significantly improve the proportion with a ROSC or who were discharged from hospital alive.

Electrolyte disorders

Abnormal electrolyte concentrations occur commonly in hospitalized patients and may produce a variety of clinical symptoms, cause lack of response to therapeutics for primary clinical conditions, and affect clinical outcome. Recognition of electrolyte disturbances requires a high index of suspicion by the clinician for such a disturbance and prompt therapy to ensure a positive and timely outcome for the patient. This article discusses electrolyte abnormalities that occur in critically ill patients, with a review of diseases commonly associated with each electrolyte disturbance, and their recommended management.

Magnesium sulfate in the treatment of refractory ventricular fibrillation in the prehospital setting

OBJECTIVE

To determine if magnesium sulfate (MgSO(4)) improves outcome in cardiac arrest patients initially in ventricular fibrillation (VF).

METHODS

Randomized, prospective, double blind, placebo-controlled, multicenter prehospital trial using 2 g of MgSO(4). Eligible patients were non-traumatic cardiac arrest patients (> or =18 years of age) presenting in VF. The protocol included those patients refractory to three electroshocks. Epinephrine and either 2 g of MgSO(4) or placebo (normal saline) were then administered. The primary outcome variable was return of spontaneous circulation (ROSC) in the field and a perfusing pulse on arrival at the ED. Secondary endpoints included admission to the hospital (ADMT) and hospital discharge (DISC). IRB approval was obtained at all participating centers.

RESULTS

Total 116 patients (58 MgSO(4), 58 placebo) were enrolled during the period from 4/1992 to 10/96 with 109 available. There were no significant differences between the groups in baseline characteristics and times to cardio pulmonary resuscitation (CPR), advanced life support (ALS), and first defibrillation, except for time to study drug administration. There was no significant differences in ROSC (placebo, 18.5%, and MgSO(4), 25.5%, P=0.38), ADMT (placebo rate=16.7%, MgSO(4)=16.4%, P=1.0) or DISC (placebo rate=3.7%, MgSO(4)=3.6%, P=1.0).

CONCLUSIONS

We failed to demonstrate that the administration of 2 g of MgSO(4) to prehospital cardiac arrest patients presenting in VF improves short or long term survival.

Comparison of infrared thermometer with thermocouple for monitoring skin temperature

OBJECTIVE

To test the hypothesis that the infrared thermometer (Genius) is comparably useful with thermocouples that are routinely used for skin temperature monitoring.

DESIGN

Prospective, controlled, not blinded study.

SETTING

Operating room of a university hospital.

SUBJECTS

Ten healthy male volunteers.

INTERVENTIONS

Volunteers were minimally clothed and were initially warmed by a forced air warmer until they became vasodilated at the finger and the foot for approximately 30 mins. Subsequently, they were kept in the room with no blanket.

MEASUREMENTS AND MAIN RESULTS

Skin temperatures were measured continuously with the Mon-a-Therm thermocouple and were also measured with the Genius thermometer just before and after the warming and subsequently every 10 mins for 70 mins. Forearm and finger-tip skin temperatures and skin-surface temperature gradients (from arm to finger and from calf to toe) measured by the Genius thermometer were compared with those measured by the Mon-a-Therm thermocouple using linear regression and Bland and Altman statistics. Forearm temperature and finger-tip temperature ranged from approximately 31 degrees to approximately 36.5 degrees C (87.8-97.7 degrees F) and approximately 22.5 degrees to approximately 36 degrees C (72.5-96.8 degrees F), respectively. Gradients (from arm to finger and from calf to toe) ranged from approximately -3 degrees to approximately 10 degrees C (26.6-50.0 degrees F) and approximately -3 degrees to approximately 11 degrees C (26.6-51.8 degrees F), respectively. Correlations between the temperatures measured by the Genius thermometer and those by the Mon-a-Therm thermocouple were similar and reliable. The correlation coefficients were as follows: 0.78 at forearm, 0.97 at finger-tip, and 0.97 at skin-surface temperature gradients.

CONCLUSIONS

The infrared thermometer with a special probe is useful to measure the change of skin-surface temperatures and to evaluate the severity of shock in patients.

Effects of magnesium sulfate on electrical ventricular defibrillation of dogs

Magnesium ion infusion has been reported for treatment of hypomagnesemia often associated with myocardial infarction and with surgeries involving cardiopulmonary bypass (CPB). Magnesium infusion before CPB has been reported to adversely affect the ability to defibrillate after CPB. However, there are also reports of magnesium ion infusion facilitating defibrillation of refractory ventricular fibrillation. This study evaluated the isolated effect of magnesium ion infusion on the shock intensity requirements for electrical defibrillation. The electric current required to defibrillate with 50% success (the ED50) was estimated in five mongrel dogs at baseline and again after each of four magnesium sulfate (80 mg/kg) infusions. The total serum magnesium level increased from 2.32 +/- 0.08 mg/dL (mean +/- SD) to 7.92 +/- 0.80 mg/dL. The mean estimated ED50 decreased from 12.8 +/- 2.9 A at baseline, to 11.1 +/- 0.8 A after the fourth infusion (P < .05), decreasing the delivered energy by 25%. Magnesium sulfate infusion was associated with a significant decrease in the electrical requirements for defibrillation. Key words: magnesium, electrical ventricular defibrillation.

Cardiopulmonary resuscitation: a review for clinicians

Attempts at cardiopulmonary resuscitation (CPR) date from antiquity, but it is only in the last 50 years that a scientifically-based methodology has been developed. External chest compressions is the standard method for managing circulatory arrest, however, numerous alterations of this technique have been proposed in attempts to improve outcome from CPR. Defibrillation is the single most important therapy for the management of ventricular fibrillation or pulseless ventricular tachycardia. Adrenergic agents used to improve myocardial and cerebral perfusion are also the subject of considerable investigation with new agents entering clinical study. This paper reviews the history, current techniques and pharmacotherapy as well as controversial issues in the management of patients with cardiac arrest.

Magnesium in cardiac arrest (the magic trial)

The prognosis of out of hospital cardiac arrest (OHCA) is dismal. Recent reports indicate that high dose magnesium may improve survival. A prospective randomized double blind placebo controlled trial was conducted at the emergency department (ED) of Royal Perth Hospital, a University teaching hospital. Patients with OHCA of cardiac origin received either 5 g MgSO4 or placebo as first line drug therapy. The remainder of their management was standard advanced cardiac life support (ACLS). Study endpoints were: (1) ECG rhythm 2 min after the trial drug; (2) return of spontaneous circulation; (3) survival to leave the ED; (4) survival to leave intensive care; and (5) survival to hospital discharge. Of 67 patients enrolled, 31 received magnesium and 36 placebo. There were no significant differences between groups for all criteria, except that there were significantly more arrests witnessed after arrival of EMS personnel in the magnesium group (11 or 35% vs 4 or 11%). Return of spontaneous circulation occurred in seven (23%) patients receiving magnesium and eight (22%) placebo. Four patients in each group survived to leave the ED and one from the magnesium group survived to hospital discharge. There were no survivors in the placebo group. In this study, the use of high dose magnesium as first line drug therapy for OHCA was not associated with a significantly improved survival. Early defibrillation remains the single most important treatment for ventricular fibrillation (VF). Further studies are required to evaluate the role of magnesium in cardiac and cerebral resuscitation.

Magnesium sulfate solution dramatically improves immediate recovery of rats from hypoxia

This study in rats investigated the effects of 0.5 mEq/1 kg body weight of magnesium sulfate solution upon hypoxic left cardiac ventricular pressure (Part 1), optimal timing for injection of magnesium sulfate solution for successful resuscitation (Part 2) and survival benefits of magnesium sulfate after 8 or 12 min of hypoxia (Part 3) in rats resuscitated by single bolus arterial reperfusion using 2 ml of arterial blood and 6-9 micrograms epinephrine. A total of 153 pentobarbital anesthetized rats were subjected to 8 or 12 min 0.75% O2:99.25% N2 hypoxia in order to induce cardiac arrest. In Part 1, 13 rats (six control and seven injected with magnesium sulfate solution) were subjected to 12 min hypoxia and cardiac left ventricular pressure (LVP) was measured. In Part 2, 47 rats were exposed to 12 min of hypoxia. Normal saline or magnesium sulfate solution was injected prior to hypoxia, at 2 or 4 min of hypoxia, to find the optimal timing of magnesium sulfate injection for successful resuscitation by arterial reperfusion. In Part 3, 90 rats were studied to determine 7-day survival. Two control groups were injected with saline during 8 min (29 rats) or 12 min (18 rats) of hypoxia and two groups received magnesium sulfate solution during 8 min (14 rats) and 12 min (29 rats) of hypoxia. Magnesium sulfate fully reversed the hypoxic increase of LVP and improved survival after 12 min of hypoxia from approximately 15 (control) to 100% if given during the first 2.5 min of hypoxia. The main cause of the progressive resuscitation failure after 8 or 12 min control hypoxia was a progressive increase in acute cardiac failure. Although magnesium sulfate solution significantly improved immediate recovery after hypoxia (8 and 12 min), mortality due to reperfusion injury (para or tetraplegia) was observed in 62% of rats surviving longer than 1 day after 8 min and 100% after 12 min hypoxia (in control rats-50 and 100%, respectively). The overall survival after hypoxia, with or without reperfusion injury, was relatively low: 28% in control groups after 8 min and 17% after 12 min. In the magnesium sulfate groups these numbers were only slightly higher, 36 and 21%, respectively. It is concluded that in conjunction with arterial reperfusion magnesium sulfate infusion is very effective in improving acute cardiac recovery after 8-12 min of hypoxia. The likely mechanism of magnesium sulfate action is decreased incidence of ventricular fibrillation (VF) and asystole, and possibly myocardial relaxation during and after hypoxia, a property which may qualify MgSO4 as an ischemic preconditioning agent. Poor long-term survival rates of rats exposed to hypoxia and resuscitated by intraarterial reperfusion do not support its use in resuscitation.

Current concepts in cardiopulmonary resuscitation

The "chain of survival" is important in the resuscitation of a patient who has had a cardiac arrest. The provision of Basic Life Support (BLS) and Advanced Cardiac Life Support (ACLS) is essential in this "chain of survival." Both BLS and ACLS have undergone several revisions since their initial inception. This article reviews (1) the current established and investigational issues of cardiopulmonary resuscitation, (2) the incidence and outcomes of anesthesia-related cardiac arrest, (3) the use of cardiopulmonary bypass in resuscitation, and (4) cerebral protection during and after resuscitation.

Comparison of infrared ear thermometer derived and equilibrated rectal temperatures in estimating pulmonary artery temperatures

OBJECTIVES

To investigate the clinical accuracy of infrared ear thermometer derived and equilibrated rectal temperatures in estimating core body temperature. The clinical bias (i.e., mean difference between body sites), and variability (SD of the differences) of simultaneous temperatures were compared with pulmonary artery temperatures. Clinical repeatability (pooled SD of triplicate reading differences) was also examined for three ear infrared thermometers.

DESIGN

Prospective clinical study.

SETTING

A multidisciplinary, adult intensive care unit.

PATIENTS

Twenty patients with an existing pulmonary artery catheter were studied in a multidisciplinary, adult intensive care unit.

INTERVENTIONS

A single operator using optimum ear infrared technique and masked to ear and rectal temperatures recorded triplicate measurements with each of three infrared ear thermometers, each over a 4-min period with each infrared thermometer, while an assistant recorded temperatures. Infrared and rectal temperatures were compared with a simultaneous pulmonary artery temperature.

MEASUREMENTS AND MAIN RESULTS

Infrared ear thermometers and rectal thermometers were calibrated daily, and pulmonary artery catheters were calibrated on removal from the patient. Patients were grouped into afebrile and febrile groups, based on initial pulmonary artery temperature. Bias and variability were compared between thermometers using analysis of variance. Clinical bias, but not variability, was significantly different between three ear infrared thermometers (0.16 +/- 0.46 degrees C, 0.07 +/- 0.38 degrees C, and -0.22 +/- 0.47 degrees C). The repeatability was not different between ear infrared thermometers (range 0.13 degrees C to 0.14 degrees C). Rectal temperature had a significantly greater bias (average 0.3 degrees C), but less variability (average 0.2 degrees C). Bias was increased, and variability decreased for both rectal and infrared ear temperatures when pulmonary artery temperature was increased.

CONCLUSIONS

The three infrared ear thermometers studied provided a closer estimate of core body temperature than equilibrated rectal temperature. Clinical bias was greatest in febrile vs. afebrile intensive care unit patients.

Pilot study of intravenous magnesium sulfate in refractory cardiac arrest: safety data and recommendations for future studies

Recent case reports have evidenced a temporal association between administration of i.v. magnesium sulfate (M) and resuscitation from prolonged cardiac arrest refractory to standard (S) ACLS attempts. However, speculation has arisen that M as a vasodilator, may decrease aortic diastolic and coronary perfusion pressure (CPP), aortic systolic and cerebral perfusion pressures (CePP), which may decrease resuscitation rates and neurologic recovery, as compared to standard ACLS alone (SA).

OBJECTIVE

To resolve positive beginning evidence vs. negative theory, we conducted a pilot study of M+S vs. SA in refractory cardiac arrest on resuscitation rates (% R, return of stable pulses > 30 min without CPR, first in-hospital cardiac arrest > 5-min duration) and neurologic recovery/survival to hospital discharge (SHD).

METHODS

All patients from 1 January 1990-31 December 1991 at Rose Hospital, in cardiac arrest refractory to S through the first epinephrine dose (including 3 defibrillation attempts with pulseless VT/VF) were included in the data analysis, except: (1) patients with trauma, known poisoning, < 18 years, pregnancy excluded; (2) Standard ACLS alone patients with cardiac arrest < 5-min duration were not included in the SA comparison group, because the shortest cardiac arrest time before i.v. MgSO4 administration in the M+S group was 5 min. M+S (N = 29) and SA (N = 33) groups were also comparable on mean age (72-73 years) in this open-label prospective case-matched control group study.

RESULTS

SHD rates were nearly equivalent between M+S (5.2%) and SA (4.5%). Complete or partial neurologic recovery, as best neurologic status post-R, occurred in 21% (6/29) M+S patients vs. 9% (3/33) SA (P = 0.17), even though cardiac arrest time on the study code call for resuscitated patients averaged shorter with SA (14.2 min) than M+S (19.8 min). M was frequently administered late in the resuscitation attempt--code call to M administration averaged 16.5 min (< 10 min in only 4/28 patients). A trend toward increased % R with M was evidenced: 21% (7/33) SA vs. 35% (10/29) M+S (P = 0.21). A temporal association between M administration and first return of spontaneous circulation (ROSC) was also documented in 4 of 10 M+S patients (pulseless electrical activity (3)/pulseless VT (1)), who had first ROSC/R occur within 0.5-2.25 min following first i.v. M bolus delivery, after 11-30 min (mean = 20 min) of continuous pulseless rhythm refractory to standard ACLS. All M+S resuscitations occurred within the dose range 2.5-5 g (i.v. push): 3/6 (50%) and 7/13 (54%) R occurred with 1-3 g and 4-5 g MgSO4, respectively (at least 11/13 patients had peripheral i.v. delivery with 4-5 g M). Analyzing post-ROSC hypotension proved important, as 50% of pts with first recorded systolic BP post-ROSC < 90 mmHg were resuscitated vs. 83% with > 90 mmHg (P = 0.10). A trend toward increased post-ROSC hypotension was evidenced with i.v. MgSO4: Recorded first or second systolic BP < 90 mmHg post-ROSC occurred in 66% of M+S vs. 42% of SA patients. All 3 M+S patients having a wide open i.v. levophed infusion as vasopressor support, started immediately post-ROSC/i.v. MgSO4 with systolic BP < 90 mmHg and continued at least 15 min (titrating to a systolic BP approximately 110 mmHg), had a temporal association between M delivery and R after 14-30 min of continuous pulselessness refractory to S.

CONCLUSION

Human research determining whether i.v. MgSO4 increases long-term survival from refractory cardiac arrest should be vigorously pursued, as it is safe to proceed given the above described considerations.

The use of antiarrhythmics in advanced cardiac life support

Antiarrhythmic agents have been used to treat malignant ventricular arrhythmias in the setting of acute myocardial ischemia with proven efficacy for many years. Thus, it has been presumed that these agents would be efficacious for the treatment of cardiac arrest. Unfortunately, hard data supporting this contention are unavailable to date. Furthermore, some of the experimental data in this area are conflicting, especially regarding the relative effects of lidocaine and bretylium. Thus, little definitive can be said based on experimental information. In two randomized patient studies, lidocaine and bretylium performed comparably. Because of the frequent use of lidocaine and thus the familiarity of most health care professionals with its use, it makes educational sense to utilize lidocaine as the antiarrhythmic drug of first choice during the cardiac arrest sequence. Recent data suggesting that amiodarone may be efficacious in patients with recurrent arrhythmias require additional confirmation. Although antiarrhythmic agents have been shown to be effective in the treatment of malignant arrhythmias in patients with acute myocardial infarction, their use prophylactically for patients with suspected infarction (advocated in the past) has recently undergone reevaluation. It is now clear that despite a reduction in ventricular fibrillation, overall mortality may be increased. This may be because the prophylactic treatment of patients with suspected infarction includes a large number of patients not at risk for ventricular fibrillation who still may be at risk for drug toxicity. Thus, prophylactic administration of lidocaine to all patients with suspected acute myocardial infarction can no longer be recommended. There are inadequate data upon which to base a recommendation concerning the use of lidocaine in patients receiving thrombolytic therapy. The group most likely to benefit from lidocaine are patients with ST segment elevation who present early after the onset of acute myocardial infarction. The use of lidocaine in this group requires additional study. At present, despite enthusiasm for the prophylactic use of magnesium for the treatment of arrhythmias, data are inadequate to support its routine administration. However, given the importance of magnesium and potassium levels in the genesis of malignant arrhythmias, their levels in plasma should be assessed, and abnormalities should be promptly corrected. The potential uses of antiarrhythmic agents during advanced cardiac life support span a remarkably diverse number of applications. For the purpose of this review, only the use of these agents during CPR and during the early hours of acute or suspected acute myocardial infarction will be considered.

New whole blood analyzers and their impact on cardiac and critical care

Miniaturized whole blood biosensors, patient-focused hospitals, and rising expectations of patients and physicians are shifting laboratory diagnostics to the point of care. Expanding transplantation and intensive care are increasing the need for rapid test results. Whole blood analysis improves accuracy, eliminates centrifugation, reduces response time, and conserves blood volume. Several hand-held, and over 20 portable or transportable whole blood instruments are now available. Criteria for instrument evaluation include test menus, point-of-care features, analysis time, on-site performance, and information integration. Whole blood analyzers measure several vital indicators (pO2, pCO2, pH, hematocrit, K+, Ca2+, Na+, Cl-, glucose, and lactate) simultaneously in less than 2 min with less than 200 microliters of whole blood. Other in vitro tests are available (Mg2+, osmolality, CO2 content, urea nitrogen, beta-hydroxybutyrate, hemoglobin, coagulation) or under development (HCO3- phosphorus). Some can be monitored in vivo (O2 saturation, pO2, pCO2, pH, glucose) or ex vivo. The clinical impact is demonstrated by ionized calcium, now established in importance for cardiac and neurologic problems, and ionized magnesium, a promising new measurement. The hybrid laboratory (a composite of conventional clinical laboratory and patient-focused testing), performance maps, and quality paths facilitate implementation of new whole blood analyzers for optimal support of cardiac and critical care, and improved patient outcomes (prospects).