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Biomedical subjects

Roger D White

Publications and source records attributed to Roger D White.

At least 19 recordsLinked to original sources

Epidemiology, trends, and outcome of out-of-hospital cardiac arrest of non-cardiac origin.

INTRODUCTION: The majority of victims who experience out-of-hospital cardiac arrest (OHCA) have ventricular fibrillation (VF) as the presenting rhythm and are thought to have a cardiac etiology for their arrest. Over the past decade, the incidence of VF OHCA has declined. The aims of this study were to describe the epidemiology of OHCA of non-cardiac origin in Olmsted County MN and to determine the trends that have occurred over time. METHODS: All residents with a traumatic OHCA from 1995 to 2005 were included for analysis. OHCA data were collected prospectively according to the Utstein method. Cardiac arrests were classified as cardiac or non-cardiac in origin and the etiology determined based on autopsy reports, electronic medical records, and/or emergency medical services reports. RESULTS: During the study period, 414 OHCAs were identified, 90 (21.7%) of which were classified as non-cardiac. Mean age was 61.5+/-19.7 years. Response time was 7.73+/-2.9 min, and 40 (44.4%) were bystander-witnessed. Sixty-eight (75.6%) arrests occurred at home, 13 (14.4%) in a public place, and 9 (10%) in other locations. Bystander CPR was performed in 17 (18.9%) cases. The presenting rhythm was VF in 2 (2.2%) cases, PEA in 54 (60%), and asystole in 34 (37.8%). Eight (8.9%) patients survived to hospital discharge. Respiratory failure (35.6%), unknown (15.6%), and pulmonary embolism (13.3%) were the most common etiologies. The mean percentage of arrests due to a non-cardiac cause in three sequential time-periods (1995-1999, 2000-2002, 2003-2005) was 9.4%, 20.1% and 37.7%, respectively. CONCLUSIONS: Over the study period, 21.7% of OHCAs were non-cardiac in origin. PEA was the most common presenting rhythm and respiratory failure the most common etiology. 8.9% of patients survived. The decreasing number of VF arrests may be a contributing factor to the increasing proportion of OHCAs of non-cardiac etiology observed in the out-of-hospital setting.

Algorithms↗

Outcome prediction for guidance of initial resuscitation protocol: Shock first or CPR first.

BACKGROUND: Ventricular fibrillation (VF) is treated optimally with a defibrillation shock shortly after patient collapse, but may benefit from initial cardiopulmonary resuscitation (CPR) if the shock is delayed. An objective measure of potential responsiveness to defibrillation could help decide optimal initial therapy. METHODS AND RESULTS: a new electrocardiogram (ECG) analysis algorithm was compared with response interval (call-to-shock) for prediction of patient outcome in a population of 87 VF patients in the Rochester, Minnesota area. In a retrospective analysis, both call-to-shock interval (p = 0.009) and ECG analysis (p < 0.001) predicted neurologically intact survival, with ECG analysis the stronger predictor (p = 0.034). When applied to advising initial patient treatment, ECG analysis compared favorably with the call-to-shock interval. Using a 7 min call-to-shock time criterion, 69% of patients would receive shocks first treatment using ECG analysis versus 67% using the call-to-shock interval (p = NS), 94% of survivors would retain successful shocks first treatment versus 85% (p = NS), and 48% of non-survivors receive alternate CPR-first treatment versus 45% (p = NS). Similarly, no significant differences were observed between ECG analysis and call-to-shock interval using an 8 min criterion. CONCLUSIONS: Both call-to-shock interval and a real-time ECG analysis are predictive of patient outcome. The ECG analysis is more predictive of neurologically intact survival. Moreover, the ECG analysis is dependent only upon the patient's condition at the time of treatment, with no need for knowledge of the response interval, which may be difficult to estimate at the time of treatment.

Cardiopulmonary Resuscitation↗

A comparative analysis of short- and long-term outcomes after ventricular fibrillation out-of-hospital cardiac arrest in patients with ischemic and nonischemic heart disease.

Although ventricular fibrillation (VF) out-of-hospital cardiac arrest (OHCA) occurs primarily in the setting of severe ischemic heart disease (IHD), a significant proportion of events occurs in patients who do not have severe IHD. The relative effect of IHD on survival after VF OHCA is unknown. All residents of Rochester, Minnesota, who presented with a VF OHCA from November 1990 to December 2004, treated by emergency medical services, were included in the study. During the study, emergency medical services treated 208 patients (64.1 +/- 13.6 years of age) for VF OHCA, with an average call-to-shock time of 6.3 +/- 1.8 minutes. Of these patients, 156 had IHD and 39 had non-IHD. In 13, the underlying heart disease was unknown. Eighty-seven patients (41.8%) survived to hospital discharge with neurologic recovery (66 with IDH [42%] vs 21 with non-IHD [54%], p = 0.211)]. Five-year survival was 79 +/- 6% for patients with IHD versus 100% for those with non-IHD (p = 0.047). After adjustment for other patient characteristics, IHD was not predictive of 5-year survival (hazard ratio [HR] 2.2, 95% confidence interval [CI] 0.7 to 9.8, p = 0.177). Variables associated with poor outcomes included age >65 years (HR 4.9, 95% CI 2.0 to 13.4, p = 0.0003), ejection fraction <0.35% (HR 3.0, 95% CI 1.3 to 7.3, p = 0.012), and hypertension (HR 4.9, 95% CI 1.4 to 16.3, p = 0.001). In patients with IHD, use of an implantable cardioverter-defibrillator (HR 0.32, 95% CI 0.16 to 0.88, p = 0.024) and statin therapy (HR 0.68, 95% CI 0.17 to 0.73, p = 0.001) were associated with decreased mortality. In conclusion, compared with patients with non-IHD, those with IHD had similar short- and long-term survival rates. Long-term survival in patients with IHD was primarily influenced by other co-morbid conditions. Nonetheless, in patients with IHD, use of an implantable cardioverter-defibrillator and statin therapy were associated with higher long-term survival rates.

Age Factors↗

Preventing sudden death with n-3 (omega-3) fatty acids and defibrillators.

BACKGROUND: Because interventions that prevent and treat events due to cardiovascular disease are applied to different, but overlapping, segments of the population, it can be difficult to estimate their effectiveness if formal calculations are not available. METHODS: Markov chain analysis, including sensitivity analysis, was used with a hypothetical population resembling that of Olmsted County, MN, aged 30 to 84 in the year 2000 to compare the estimated impact of three interventions to prevent sudden death: (1) raising blood levels of n-3 (omega-3) fatty acids, (2) distributing automated external defibrillators (AEDs), and (3) implanting cardioverter defibrillators (ICDs) in appropriate candidates. The analysis was performed in 2004, 2005, and 2006. RESULTS: Raising median n-3 fatty acid levels would be expected to lower total mortality by 6.4% (range from sensitivity analysis = 1.6% to 10.3%). Distributing AEDs would be expected to lower total mortality by 0.8% (0.2% to 1.3%), and implanting ICDs would be expected to lower total mortality by 3.3% (0.6% to 8.7%). Three fourths of the reduction in total mortality due to n-3 fatty acid augmentation would accrue from raising n-3 fatty acid levels in the healthy population. CONCLUSIONS: Based on central values of candidacy and efficacy, raising n-3 fatty acid levels would have about eight times the impact of distributing AEDs and two times the impact of implanting ICDs. Raising n-3 fatty acid levels would also reduce rates of sudden death among the subpopulation that does not qualify for ICDs.

Adult↗

Analysis of the ventricular fibrillation waveform in refibrillation.

OBJECTIVES: Frustrating outcomes are driving investigation of alternative resuscitation protocols. Previous analysis of the ventricular fibrillation (VF) waveform has focused on guiding whether to shock immediately or to delay for delivery of cardiopulmonary resuscitation in the case of presenting VF. The same issues emerge in the case of refibrillation. MEASUREMENTS AND MAIN RESULTS: All cases of witnessed VF cardiac arrest in the Rochester, MN, area in a 9-yr period were analyzed. Rochester rescuers employed an early defibrillation protocol during the study period. A summary measure of the VF waveform before the shock delivered in 35 incidents of refibrillation was compared with the time elapsed from the initial shock, the intervening electrocardiographic rhythm, ambulance response time, and call-to-shock time for prediction of early return of spontaneous circulation and of neurologically intact survival. VF waveform analysis separated patients with good outcomes when treated with early defibrillation of refibrillation from those without good outcomes more clearly than other predictors. CONCLUSIONS: Analysis of VF waveform offers promise for real-time guidance of resuscitation efforts on the basis of individual patient characteristics, in refibrillation and in the initial shock. It has advantages over guidance based on individual or aggregate system response times.

Cardiopulmonary Resuscitation↗

Acquired long QT syndrome and elective anesthesia in children.

We present the case of a child who had had a previous episode of torsades de pointes (TdP) and who was scheduled for elective surgery under general anesthesia. The pathophysiology of this condition and the anesthesia concerns are discussed. An 8-year-old male with a history of osteogenic sarcoma had undergone an uneventful limb salvage procedure 2 years earlier. During a subsequent admission to the hospital, he had had a cardiopulmonary arrest with complete recovery. Telemetry electrocardiogram (ECG) rhythm recordings obtained during the event showed TdP that degenerated into ventricular fibrillation, which then terminated spontaneously. On a subsequent ECG, the QTc interval was 694 ms. The prolonged QT interval was attributed to homeopathic use of cesium chloride supplements and the QT interval normalized after cesium was stopped. He presented for an elective procedure and, with an anesthetic plan that emphasized medications without known effect on the QT interval, had an uneventful perioperative course. The optimal anesthesia plan for patients with prolonged QT or those suspected to be at risk for prolongation of the QT interval has not been well described. Available evidence suggests that using total intravenous anesthesia with propofol may be the safest and was used uneventfully in this case. Additionally, this case emphasizes the need to inquire about the use of supplements and naturopathic medications, even in children, that may have life-threatening side effects or interactions with anesthetic agents.

Anesthesia, General↗

Comparative efficacy of monophasic and biphasic waveforms for transthoracic cardioversion of atrial fibrillation and atrial flutter.

BACKGROUND: Transthoracic cardioversion fails to restore sinus rhythm in 6% to 33% of patients with atrial fibrillation. This study sought to determine the relative efficacy of biphasic waveforms compared with monophasic waveforms in the treatment of atrial arrhythmias. METHODS: A total of 912 patients underwent 1022 transthoracic cardioversions between May 2000 and December 2001. A monophasic damped sine waveform was used in the first 304 cases, and a rectilinear biphasic defibrillator was used in the next 718 cases. RESULTS: Use of a biphasic waveform was associated with 94% success in conversion to sinus rhythm compared with 84% with a monophasic waveform (P < .001). The cumulative energy required to restore sinus rhythm was lower with biphasic shocks in both atrial fibrillation and atrial flutter groups (554 +/- 413 J for monophasic vs 199 +/- 216 J for biphasic shocks in the atrial fibrillation group, P < .001; 251 +/- 302 J vs 108 +/- 184 J, respectively, in the atrial flutter group, P < .001). In a multivariate analysis, use of a biphasic shock was associated with a 3.9-fold increase in success of cardioversion. CONCLUSION: When used to cardiovert atrial arrhythmias, the rectilinear biphasic waveform was associated with higher success rates and lower cumulative energies than the monophasic damped sine waveform.

Aged↗

Prospective, randomized comparison of two biphasic waveforms for the efficacy and safety of transthoracic biphasic cardioversion of atrial fibrillation.

OBJECTIVES: The purpose of this study was to determine if there is a difference in commercially available biphasic waveforms. BACKGROUND: Although the superiority of biphasic over monophasic waveforms for external cardioversion of atrial fibrillation (AF) is established, the relative efficacy of available biphasic waveforms is less clear. METHODS: We compared the effectiveness of a biphasic truncated exponential (BTE) waveform and a biphasic rectilinear (BR) waveform for external cardioversion of AF. Patients (N = 188) with AF were randomized to receive transthoracic BR shocks (50, 75, 100, 120, 150, 200 J) or BTE shocks (50, 70, 100, 125, 150, 200, 300, 360 J). Shock strength was escalated until success or maximum energy dose was achieved. If maximum shock strength failed, patients received the maximum shock of the opposite waveform. Analysis included 141 patients (71 BR, 70 BTE; mean age 66.5 +/- 13.7. Forty-seven randomized patients were excluded because of flutter on precardioversion ECG upon blinded review (n = 25), presence of intracardiac thrombus (n = 7), or protocol deviation (n = 15). Groups were similar with regard to clinical and echocardiographic characteristics. RESULTS: The success rate was similar for the two waveforms (93% BR vs 97 BTE, P = .44), although cumulative selected and delivered energy was less in the BTE group. Only AF duration was significantly different between successful and unsuccessful patients. No significant complications occurred. CONCLUSIONS: Biphasic waveforms were very effective in transthoracic cardioversion of AF, and complication rates were low. No significant difference in efficacy was observed between BR and BTE waveforms. Impedance was not an important determinant of success for either biphasic waveform.

Aged↗

Transthoracic impedance does not affect defibrillation, resuscitation or survival in patients with out-of-hospital cardiac arrest treated with a non-escalating biphasic waveform defibrillator.

OBJECTIVE: This is a study of the influence of transthoracic impedance (TTI) on defibrillation, resuscitation and survival in patients with out-of-hospital cardiac arrest (OHCA), treated with a non-escalating impedance-compensating 150 J biphasic waveform defibrillator. METHODS: Cardiac arrest data from two EMS systems were analyzed retrospectively. All witnessed arrests from patients who presented with a shockable rhythm and were treated initially by BLS personnel were included (n = 102). For each defibrillation and resuscitation outcome variable, we tested differences in mean TTI for successful versus unsuccessful outcome. The effect of call-to-shock time on overall outcome was also examined. RESULTS: Initial shocks defibrillated 90% [83-95%] (95% confidence interval) of patients. Cumulative success with two shocks was 98% [93-100%] and with three shocks was 99% [95-100%]. TTI averaged 90 +/- 23 Omega. First-shock success, cumulative success through two shocks and cumulative success through the first-shock series were unrelated to TTI, as were BLS ROSC, pre-hospital ROSC, hospital admission and discharge. In contrast and consistent with previous findings, call-to-shock time was highly predictive of survival. CONCLUSIONS: High impedance patients were defibrillated by the biphasic waveform used in this study at high rates with a fixed energy of 150 J and without energy escalation. Rapid defibrillation rather than differences in patient impedance accounts for resuscitation success.

Cardiography, Impedance↗

Sex differences in outcome after ventricular fibrillation in out-of-hospital cardiac arrest.

INTRODUCTION: Previous studies have shown that early defibrillation programs improve survival after an out-of-hospital cardiac arrest (OHCA). Reports also suggest that women fare worse than men do after cardiovascular events, but there is no population-based study of sex differences after an OHCA with early defibrillation. We, therefore, compared the short- and long-term survival and quality-of-life (QOL) in women and men after an OHCA. METHODS: All patients with a ventricular fibrillation (VF) OHCA who received early defibrillation in Olmstead County, Minnesota between November 1990 and December 2000 were included. Using medical records and the cardiac arrest database, the short- and long-term survival and QOL based on a SF-36 survey of each sex were compared. Adjusted QOL scores were obtained by using age- and sex-specific norms from a sample of the general U.S. population; an adjusted score of 50 (normalized mean) was considered normal. RESULTS: Thirty-seven female and 163 male patients presented with a VF OHCA and early defibrillation. Survival to hospital admission was significantly better for women than men [30 female survivors to admission (81%), 112 male (69%), p = 0.04]. Paradoxically, survival to discharge among those admitted was worse for women [13 female survivors to discharge (43%), 66 male (61%), p = 0.04]. The average length of follow-up was 4.8+/-3.0 years. The 5-year expected survival was 83% in women and 78% in men (p = 0.48). There was no difference in call-to-shock time (6+/-2, 6+/-2 min, p = 0.6) or whether the arrest was witnessed (86, 82%, p = 0.64). There was no statistical difference between women and men in age (64+/-17, 65+/-14 years), ejection fraction (40+/-17, 40+/-18%), diabetes (17, 29%, p = 0.16), hypertension (23, 28%, p = 0.58) or known CAD (27, 48%, p = 0.06). Adjusted QOL scores were similar between women and men in terms of pain (52+/-9, 52+/-10) vitality (47+/-11, 40+/-9), general health (49+/-9, 44+/-7), social function (51+/-10, 51+/-8), and mental health (50+/-10, 49+/-6). CONCLUSION: Women are more likely to survive to hospital admission following an OHCA. However, admitted women less likely to survive their hospital stay. Long-term survival and QOL are equally favorable in both sexes.

Aged↗

Evolution of a community-wide early defibrillation programme experience over 13 years using police/fire personnel and paramedics as responders.

BACKGROUND: In November 1990, a 2-year trial period was initiated in which police officers in the city of Rochester, Minnesota, were trained in the operation of automated external defibrillators (AEDs). Following the trial, the program was expanded as the city grew in population and area. In 1998 firefighters also were equipped with AEDs, bringing to a total 18 AEDs with police and fire personnel, in addition to paramedic capability. METHODS: From November 1990 to December 2003, all adult patients with atraumatic cardiac arrest with ventricular fibrillation (VF) as the presenting rhythm were included for analysis. Call-to-shock time intervals, restoration of spontaneous circulation after defibrillation shocks only (without need for vasoactive or inotropic drug administration), and neurologically intact survival (overall performance category (OPC) 1 or 2) were study end-points. RESULTS: One hundred and ninety-three patients presented in VF. Of these, 80 (41%) were discharged neurologically intact. Of the 159 VF patients whose arrest was bystander-witnessed 73 (46%) were discharged. Survival from non-VF arrest was very low (5%). Assessment of VF survivors demonstrated a quality of life, adjusted for age, gender, and disease, similar to that of the general population. CONCLUSIONS: These data demonstrate that a relatively high survival can be obtained in a city of this size and area employing a non-tiered community-wide approach within the emergency medical services (EMS) system.

Advanced Cardiac Life Support↗

Ventricular fibrillation is not provoked by chest compression during post-shock organized rhythms in out-of-hospital cardiac arrest.

INTRODUCTION: It has been proposed that chest compression (CC) can provoke recurrent ventricular fibrillation (VF) after defibrillation has restored an organized rhythm (OR). If so this would have major implications for proposed changes in resumption of CC after defibrillation, regardless of rhythm. The aim of this study was to examine our defibrillation data for evidence of post-shock CC-induced VF. METHODS: In a defibrillation program using police/fire personnel entire electrocardiograms (ECGs) from defibrillator data cards were examined for initial and post-shock rhythms and CC artifact. Successful shock rhythms were defined as either asystole or OR in the first five seconds post-shock, the latter as at least two QRS complexes during this time period. Artifact from CC was assessed for association with recurrent VF during either asystole or OR. RESULTS: Among 67 patients (pts) defibrillated by police/fire personnel VF recurred at least once in 35 (52%). Entire ECGs were available in 32 of these 35 pts. Chest compression-associated recurrent VF developed in 16 of 32 patients (50%). A total of 78 VF recurrences were observed during the period prior to administration of epinephrine (adrenaline) or other drugs. During post-shock asystole VF recurred 32 times (41% of all recurrent VF episodes); in 19 (59%) VF recurred during CC and in 13 (41%) it was spontaneous. During OR VF recurred 46 times (59% of all recurrent VF episodes); in 36 (78%) VF recurred spontaneously and in only 10 (22%) during CC. Heart rate preceding spontaneous recurrence of VF during OR was 84+/-35 beats/min, and heart rate preceding CC-associated VF recurrence during OR was 46+/-20 beats/min (p > 0.001). There was no statistically significant difference in the width of the QRS complex preceding VF recurrence in the CC-associated and spontaneous VF recurrence groups (p = 0.925). CONCLUSIONS: VF recurred following successful shocks in 52% of pts. With asystole VF recurred frequently during CC. However, during post-shock OR VF recurred unrelated to CC in most instances. Thus, resumption of CC immediately after shocks that restore an OR is unlikely to provoke recurrent VF, and resumption of CC need not be delayed.

Cardiopulmonary Resuscitation↗

Trends in treated ventricular fibrillation in out-of-hospital cardiac arrest: ischemic compared to non-ischemic heart disease.

BACKGROUND: The incidence of ventricular fibrillation (VF) out-of-hospital cardiac arrest (OHCA) treated by first responders has declined over the past decade. Since VF OHCA occurs primarily in the setting of severe coronary artery disease, primary and secondary prevention strategies may in part account for the decline. However, such strategies may not have a similar impact on non-ischemic arrest. METHODS: All Rochester Minnesota residents who presented with a VF OHCA from 1991 to 2004, treated by emergency medical services (EMS), were included in the study. Incidence rates were calculated based on the population for Rochester during the time period. Changes over time were tested using Poisson regression models. The significance of the trends was estimated according to the Mantel-Haenszel test for association, and two-tailed p-values reported. RESULTS: The overall incidence of EMS-treated VF OHCA in Rochester during the study period was 10.6 per 100,000 (95% CI 9.1-11.8). The incidence decreased significantly (p<0.001) over the study period [1991-1994: 18.2/100,000 (95% CI 13.4-21.9); 1995-1999: 11.8/100,000 (95% CI 10.4-17.9); 2000-2004: 8.7/100,000 (95% CI 6.0-13.0)]. The incidence of VF OHCA with ischemic heart disease also declined [1991-1994: 13.4/100,000 (95% CI 8.9-16.9); 1995-1999: 11.1/100,000 (95% CI 8.2-15.9); 2000-2004: 5.5/100,000 (95% CI 3.8-8.2), p<0.001]. In contrast, the incidence VF OHCA with non-ischemic heart disease increased [1991-1994: 2.1/100,000 (95% CI 1.13-3.1); 1995-1999: 2.3/100,000 (95% CI 1.9-3.7); 2000-2004: 2.9/100,000 (95% CI 2.0-3.4), p<0.001]. CONCLUSION: The incidence of VF OHCA is declining. The decline is attributable to the reduction of VF cardiac arrest with ischemic heart disease; suggesting an impact of treatment strategies targeted at coronary artery disease. The relative increasing incidence of non-ischemic VF OHCA suggests that more efforts are required to minimize mortality in this cohort population.

Adult↗

Outcomes after ventricular fibrillation out-of-hospital cardiac arrest: expanding the chain of survival.

Coronary heart disease is the most common cause of death in the United States, with ventricular fibrillation (VF) the most common initial rhythm when cardiac disease causes arrest. Survival after VF out-of-hospital cardiac arrest (OHCA) depends on a sequence of events called the chain of survival, which Includes rapid access to emergency medical services, cardiopulmonary resuscitation, defibrillation, and advanced care. Because of widespread implementation of defibrillation programs, more patients survive VF OHCAs, making subsequent care of these patients important. Early hospitalization must focus on potential neurologic injury and therapy targeted at the underlying cardiac disease and antiarrhythmic therapy for long-term secondary prevention of sudden death. Attention to certain cohorts who are at high risk despite their underlying disease, such as women and elderly patients, is necessary. These cohorts may have the greatest response to short-term and long-term therapies for cardiac rehabilitation. With these approaches, long-term survival and quality of life after VF OHCA are favorable. Broadening the focus of the chain of survival to include in-hospital and long-term care will further improve favorable outcomes achieved in an early defibrillation program.

Heart Arrest↗

Anesthesia for patients with congenital long QT syndrome.

Long QT syndrome is a malfunction of cardiac ion channels resulting in impaired ventricular repolarization that can lead to a characteristic polymorphic ventricular tachycardia known as torsades de pointes. Stressors, by increasing sympathetic tone, and drugs can provoke torsade de pointes, leading to syncope, seizures, or sudden cardiac death in these patients. Beta blockade, implantation of cardioverter defibrillators, and left cardiac sympathetic denervation are used in the treatment of these patients. However, these treatment modalities do not guarantee the prevention of sudden cardiac death. Certain drugs, including anesthetic agents, are known to contribute to QT prolongation. After reviewing the literature the authors give recommendations for the anesthetic management of these patients in the perioperative period.

Anesthesia↗

Survival of a neurologically intact patient with subarachnoid hemorrhage and cardiopulmonary arrest.

Subarachnold hemorrhage (SAH) is a relatively common cause of cardiopulmonary arrest (CPA). Long-term survival with SAH and CPA is rare, and the vast majority of those who survive have moderate to severe neurologic disability. To our knowledge, there are no prior reports of patients with SAH who experience CPA and survive without neurologic deficit. We describe a patient with SAH who experienced CPA shortly after hospital admission and survived without neurologic sequelae (Cerebral Performance Category 1). Prompt defibrillation of SAH-induced ventricular fibrillation and timely neurologic intervention are essential for good neurologic outcome.

Adult↗