Pulseless electrical activity with witnessed arrest as a predictor of sudden death from massive pulmonary embolism in outpatients

Analysis of factors associated with favorable neurological outcomes in patients with initial PEA who underwent ECPR - A secondary analysis of the SAVE-J II study

PURPOSE

This study aimed to investigate the factors of favorable neurological outcomes in patients with initial pulseless electrical activity (PEA) who underwent extracorporeal cardiopulmonary resuscitation (ECPR).

METHODS

The study analyzed data from the SAVE-J II registry, a retrospective multicenter registry involving 36 participating institutions in Japan. Patients with initial PEA were included.

RESULTS

Overall proportion of patients with favorable neurological outcomes and survival rate at hospital discharge were 8.2 % and 16.9 %, respectively. Multivariate analysis revealed that no cardiac rhythm conversion to asystole, signs of life or pupil diameter, and transient return of spontaneous circulation were significantly associated with favorable neurological outcomes. Among the cause of cardiac arrest, patients with acute coronary syndrome and pulmonary embolism had higher proportions of favorable neurological outcomes (9.7 % and 19.3 %), whereas no patients with acute aortic disease or primary cerebral disease survived. The application of strict criteria for PEA using classification and regression tree analysis resulted in favorable neurological outcomes in 32.7 % of the patients.

CONCLUSIONS

This study provides an overview of patients with PEA who underwent ECPR. Since several factors are associated with favorable neurological outcomes, patients with PEA may be candidates for ECPR if these factors are met.

Clinical Presentation and Risk Stratification of Pulmonary Embolism

Pulmonary embolism (PE) presents with a spectrum of symptoms, ranging from asymptomatic cases to life-threatening events. Common symptoms include sudden dyspnea, chest pain, limb swelling, syncope, and hemoptysis. Clinical presentation varies based on thrombus burden, demographics, and time to presentation. Diagnostic evaluation involves assessing symptoms, physical examination findings, and utilizing laboratory tests, including D-dimer. Risk stratification using tools like Wells score, Pulmonary Embolism Severity Index, and Hestia criteria aids in determining the severity of PE. PE is categorized based on hemodynamic status, temporal patterns, and anatomic locations of emboli to guide in making treatment decisions. Risk stratification plays a crucial role in directing management strategies, with elderly and comorbid individuals at higher risk. Early identification and appropriate risk stratification are essential for effective management of PE. As we delve into this review article, we aim to enhance the knowledge base surrounding PE, contributing to improved patient outcomes through informed decision-making in clinical practice.

Pulmonary Embolism in Women: A Systematic Review of the Current Literature

Cardiovascular disease is the leading cause of death in women. Pulmonary embolism (PE) is the third most-common cause of cardiovascular death, after myocardial infarction (MI) and stroke. We aimed to evaluate the attributes and outcomes of PE specifically in women and explore sex-based differences. We conducted a systematic review of the literature using electronic databases PubMed and Embase up to 1 April 2022 to identify studies investigating PE in women. Of the studies found, 93 studies met the eligibility criteria and were included. The risk of PE in older women (especially >40 years of age) superseded that of age-matched men, although the overall age- and sex-adjusted incidence of PE was found to be lower in women. Risk factors for PE in women included age, rheumatologic disorders, hormone replacement therapy or oral contraceptive pills, pregnancy and postpartum period, recent surgery, immobilization, trauma, increased body mass index, obesity, and heart failure. Regarding pregnancy, a relatively higher incidence of PE has been observed in the immediate postpartum period compared to the antenatal period. Women with PE tended to be older, presented more often with dyspnea, and were found to have higher NT-proBNP levels compared to men. No sex-based differences in in-hospital mortality and 30-day all-cause mortality were found. However, PE-related mortality was higher in women, particularly in hemodynamically stable patients. These differences form the basis of future research and outlets for reducing the incidence, morbidity, and mortality of PE in women.

A novel extracorporeal cardiopulmonary resuscitation strategy using a hybrid emergency room for patients with pulseless electrical activity

BACKGROUND

Whether extracorporeal cardiopulmonary resuscitation (ECPR) is indicated for patients with pulseless electrical activity (PEA) remains unclear. Pulmonary embolism with PEA is a good candidate for ECPR; however, PEA can sometimes include an aortic disease and intracranial haemorrhage, with extremely poor neurological outcomes, and can thus not be used as a suitable candidate. We began employing an ECPR strategy that utilised a hybrid emergency room (ER) to perform computed tomography (CT) before extracorporeal membrane oxygenation (ECMO) induction from January 2020. Therefore, the present study aimed to evaluate the effectiveness of this ECPR strategy.

METHODS

Medical records of patients who transferred to our hybrid ER and required ECPR for PEA between January 2020 and November 2021 were reviewed.

RESULTS

Twelve consecutive patients (median age, 67 [range, 57-73] years) with PEA requiring ECPR were identified in our hybrid ER. Among these patients, nine were diagnosed using an initial CT scan (intracranial haemorrhage (3); cardiac tamponade due to aortic dissection (3); aortic rupture (2); and cardiac rupture (1)), and unnecessary ECMO was avoided. The remaining three patients underwent ECPR, and two of them survived with favourable neurological outcomes. Patients not indicated for ECPR were excluded before ECMO induction.

CONCLUSION

Our ECPR strategy that involved the utilisation of a hybrid ER may be useful for the exclusion of patients with PEA not indicated for ECPR and decision making.

Inokuchi S, Masui Y, Miura K, Tsutsumi H, Takuma K, Atsushi I, Nakano M, Tanaka H, Ikegami K, Arai T, Yaguchi A, Kitamura N, Oda S, Kobayashi K, Suda T, Ono K, Morimura N, Furuya R, Koido Y, Iwase F, Nagao K, Kanesaka S, Okada Y, Unemoto K, Sadahiro T, Iyanaga M, Muraoka A, Hayashi M, Ishimatsu S, Miyake Y, Yokokawa H, Koyama Y, Tsuchiya A, Kashiyama T, Hayashi M, Oshima K, Kiyota K, Hamabe Y, Yokota H, Hori S, Inaba S, Sakamoto T, Harada N, Kimura A, Kanai M, Otomo Y, Sugita M, Kinoshita K, Sakurai T, Kitano M, Matsuda K, Tanaka K, Yoshihara K, Yoh K, Suzuki J, Toyoda H, Mashiko K, Shimizu N, Muguruma T, Shimada T, Kobe Y, Shoko T, Nakanishi K, Shiga T, Yamamoto T, Sekine K, Izuka S. Investigation and treatment of pulmonary embolism as a potential etiology may be important to improve post-resuscitation prognosis in non-shockable out-of-hospital cardiopulmonary arrest: report on an analysis of the SOS-KANTO 2012 study

Background

The prognosis of non-shockable out-of-hospital cardiac arrest is worse than that of shockable out-of-hospital cardiac arrest. We investigated the associations between the etiology and prognosis of non-shockable out-of-hospital cardiac arrest patients who experienced the return of spontaneous circulation after arriving at hospital.

Methods and Results

All subjects were extracted from the SOS-KANTO 2012 study population. The subjects were 3,031 adults: (i) who had suffered out-of-hospital cardiac arrest, (ii) for whom there were no pre-hospital data on ventricular fibrillation/pulseless ventricular tachycardia until arrival at hospital, (iii) who experienced the return of spontaneous circulation after arriving at hospital. We compared the patients' prognosis after 1 and 3 months between various etiological and presumed cardiac factors. The proportion of the favorable brain function patients that developed pulmonary embolism or incidental hypothermia was significantly higher than that of the patients with presumed cardiac factors (1 month, P < 0.0001 and P < 0.0001, respectively; 3 months, P = 0.0018 and P < 0.0001, respectively). In multiple logistic regression analysis, pulmonary embolism and incidental hypothermia were found to be significant independent prognostic factors for 1- and 3-month survival and the favorable brain function rate.

Conclusions

In patients who suffer non-shockable out-of-hospital cardiac arrest, but who experience the return of spontaneous circulation after arriving at hospital, the investigation and treatment of pulmonary embolism as a potential etiology may be important for improving post-resuscitation prognosis.

Neurologically normal survival after fibrinolysis during prolonged cardiac arrest: case report and discussion

Cardiac arrest secondary to pulmonary embolism is a devastating condition with a high mortality rate. It is currently unclear whether fibrinolysis (thrombolysis) is beneficial in this setting. We report the case of a 28-year-old woman with a pulmonary embolism who developed return of pulses following the administration of tissue plasminogen activator after 38 minutes of pulseless electrical activity cardiac arrest. She went on to make a full neurologic and cardiopulmonary recovery. This case is discussed with reference to the current literature on the subject.

Good neurological recovery after rescue thrombolysis of presumed pulmonary embolism despite prior 100 minutes CPR

We reported the case of a 70-year-old man who was admitted to neurologic wards for recurrent syncope for 3 years. Unfortunately, just 2 hours after his admission, he suddenly collapsed and failed to return of spontaneous circulation (ROSC) after a 100-minute standard cardiopulmonary resuscitation (CPR). Fortunately, he was timely suspected to have pulmonary embolism (PE) based on his sedentary lifestyle, elevated D-dimer and markedly enlarged right ventricle chamber on bedside echocardiography. After a rescue thrombolytic alteplase therapy, he was successfully resuscitated and good neurological recovery was achieved.

Evidence-based diagnosis and thrombolytic treatment of cardiac arrest or periarrest due to suspected pulmonary embolism

When a previously healthy adult experiences atraumatic cardiac arrest, providers must quickly identify the etiology and implement potentially lifesaving interventions such as advanced cardiac life support. A subset of these patients develop cardiac arrest or periarrest due to pulmonary embolism (PE). For these patients, an early, presumptive diagnosis of PE is critical in this patient population because administration of thrombolytic therapy may significantly improve outcomes. This article reviews thrombolysis as a potential treatment option for patients in cardiac arrest or periarrest due to presumed PE, identifies features associated with a high incidence of PE, evaluates thrombolytic agents, and systemically reviews trials evaluating thrombolytics in cardiac arrest or periarrest. Despite potentially improved outcomes with thrombolytic therapy, this intervention is not without risks. Patients exposed to thrombolytics may experience major bleeding events, with the most devastating complication usually being intracranial hemorrhage. To optimize the risk-benefit ratio of thrombolytics for treatment of cardiac arrest due to PE, the clinician must correctly identify patients with a high likelihood of PE and must also select an appropriate thrombolytic agent and dosing protocol.

The influence of education on appropriateness rates for CT pulmonary angiography in emergency department patients

RATIONALE AND OBJECTIVES

To evaluate appropriate utilization rates for computed tomography (CT) pulmonary angiography (CTPA) in a tertiary center emergency department (ED), before and after a health care provider educational intervention.

MATERIALS AND METHODS

Institutional Review Board-approved retrospective study. Records for 100 consecutive CTPA studies ordered by the ED were retrieved from a radiology database. Appropriateness rates for the studies were determined using information from existing literature (clinical decision rules and society guidelines). Where pretest probability was not performed, it was calculated by the authors. After ED health care provider education regarding appropriateness guidelines through a dedicated lecture and question-and-answer session, appropriateness rates for another 100 consecutive CTPA ordered by the ED were calculated.

RESULTS

In the preeducational intervention, 1% of patients had Wells scores performed, 65% were women, and 29% were age <40 years. Before CTPA, 40% patients had d-dimer testing, 15% of patients had a "negative" d-dimer, 17% had alternative explanations for chest pain, and 76% had low or intermediate pretest probability. Appropriateness rates for CTPA was 7%, and 8% of studies were positive. Postintervention, no Wells scores were performed, 59% were women, and 34% <40 years. Before CTPA, 32% of patients had d-dimer, 16% had a "negative" d-dimer, 22% had alternative explanations for chest pain, and 84% had low or intermediate pretest probability. The appropriateness rate for CTPA was 6% and 10% of studies were positive.

CONCLUSION

A single educational intervention had no effect on appropriate utilization rates for CTPA. Repeated and sustained educational interventions may help improve imaging ordering pathways through the ED and other departments.

Prospective study of the incidence of contrast-induced nephropathy among patients evaluated for pulmonary embolism by contrast-enhanced computed tomography

OBJECTIVES

Contrast-enhanced computed tomography (CECT) of the pulmonary arteries (CTPA) has become the mainstay to evaluate patients with suspected pulmonary embolism (PE) and is one of the most common CECT imaging studies performed in the emergency department (ED). While contrast-induced nephropathy (CIN) is a known complication, this risk is not well defined in the ED or other ambulatory setting. The aim of this study was to define the risk of CIN following CTPA.

METHODS

The authors enrolled and followed a prospective, consecutive cohort (June 2007 through January 2009) of patients who received intravenous (IV) contrast for CTPA in the ED of a large, academic tertiary care center. Study outcomes included 1) CIN defined as an increase in serum creatinine (sCr) of ≥ 0.5 mg/dL or ≥ 25%, 2 to 7 days following contrast administration; and 2) severe renal failure defined as an increase in sCr to ≥ 3.0 mg/dL or the need for dialysis within 45 days and/or renal failure as a contributing cause of death at 45 days, determined by the consensus of three independent physicians.

RESULTS

A total of 174 patients underwent CTPA, which demonstrated acute PE in 12 (7%, 95% confidence interval [CI] = 3% to 12%). Twenty-five patients developed CIN (14%, 95% CI = 10% to 20%) including one with acute PE. The development of CIN after CTPA significantly increased the risk of the composite outcome of severe renal failure or death from renal failure within 45 days (relative risk = 36, 95% CI = 3 to 384). No severe adverse outcomes were directly attributable to complications of venous thromboembolism (VTE) or its treatment.

CONCLUSIONS

  In this population, CIN was at least as common as the diagnosis of PE after CTPA; the development of CIN was associated with an increased risk of severe renal failure and death within the subsequent 45 days. Clinicians should consider the risk of CIN associated with CTPA and discuss this risk with patients.

Critical pathways for post-emergency outpatient diagnosis and treatment: tools to improve the value of emergency care

The decision to admit a patient to the hospital after an emergency department (ED) visit is expensive, frequently not evidence-based, and variable. Outpatient critical pathways are a promising approach to reduce hospital admission after emergency care. Critical pathways exist to risk stratify patients for potentially serious diagnoses (e.g., acute myocardial infarction [AMI]) or evaluate response to therapy (e.g., community-acquired pneumonia) within a short time period (i.e., less than 36 hours), to determine if further hospital-based acute care is needed. Yet, such pathways are variably used while many patients are admitted for conditions for which they could be treated as outpatients. In this article, the authors propose a model of post-ED critical pathways, describe their role in emergency care, list common diagnoses that are amenable to critical pathways in the outpatient setting, and propose a research agenda to address barriers and solutions to increase the use of outpatient critical pathways. If emergency providers are to routinely conduct rapid evaluations in outpatient or observation settings, they must have several conditions at their disposal: 1) evidence-based tools to accurately risk stratify patients for protocolized care, 2) systems of care that reliably facilitate workup in the outpatient setting, and 3) a medical environment conducive to noninpatient pathways, with aligned risks and incentives among patients, providers, and payers. Increased use of critical pathways after emergency care is a potential way to improve the value of emergency care.

Underlying cause discovered for a prior idiopathic AMI

The authors previously reported on an active, young male with normal coronaries who sustained an acute myocardial infarction (AMI). The acute cause was a coronary thrombus; however, the cause of this thrombus and a definitive diagnosis remained elusive for 18 months until a new series of events, including symptoms of breathlessness, dizziness and collapse led to acute hospital admission. CT scan revealed numerous deep venous thromboses in the right leg and bilateral pulmonary emboli (PE). Acute pharmacological thrombolysis eliminated breathlessness and significantly reduced the risk of mortality. Clinical consensus suggests a coagulopathy, requiring indefinite treatment with Warfarin. In young individuals presenting with AMI, lifestyle, personal, family and clinical history should be considered and coronary artery disease should not be assumed until further tests have eliminated coagulopathy. In those presenting with breathlessness and a history which includes AMI, a CT scan is indicated to eliminate concerns of venous thromboembolism generally and PE specifically where untreated survival times are short.

Fibrinolysis and thrombectomy for massive pulmonary embolus

Treatment options for massive and submassive pulmonary embolus may include hemodynamic support, fibrinolysis, anticoagulation, and thrombectomy. Selection of the appropriate therapy requires scrutiny of the patient's hemodynamic status, preexisting conditions, risk of complications, and availability of services at the treatment center. This article illustrates a case of successful fibrinolysis and thrombectomy in a woman with massive pulmonary embolus. A discussion of the indications, benefits, and disadvantages of several pharmacologic, radiologic, and surgical interventions considered in pulmonary embolus will follow.

Thrombolytics for Cardiac Arrest: Case Report and Systematic Review of Controlled Trials

Objective:

To describe a successful case involving the use of tenecteplase during cardiac arrest for presumed pulmonary embolism (PE) and to systematically review the evidence from controlled trials supporting the efficacy and safety of thrombolysis during cardiac arrest.

Case Summary:

A 48-year-old male presented to the emergency department with an acute onset of shortness of breath that began approximately 2 hours prior to presentation. Prior to undergoing a computed tomography (CT) scan to rule out PE, the patient went into cardiac arrest, with an initial rhythm of pulseless electrical activity at a rate of 140 beats/min. Cardiopulmonary resuscitation (CPR) was initiated and, due to suspected PE, a bolus dose of tenecteplase 50 mg was administered immediately following a single 1-mg dose of epinephrine. CPR was continued and 4 additional 1-mg doses of epinephrine and three 1-mg doses of atropine were given. After 13 minutes of CPR, return of spontaneous circulation (ROSC) was achieved, with a blood pressure of 144/50 mm Hg. After the patient was stabilized, a CT scan demonstrated extensive bilateral pulmonary emboli in most segmental arteries. He was admitted to the intensive care unit where he was sedated, paralyzed, and treated with induced hypothermia for 24 hours. He was discharged from the hospital 2 weeks later on warfarin, with no noted neurologic deficits.

Discussion:

A systematic search of MEDLINE (1950-August 2010), Embase (1980-August 2010), and Google Scholar (to August 2010) was conducted to identify prospective controlled trials that investigated the use of thrombolytic medications to treat cardiac arrest. Five trials involving 1544 undifferentiated cases of cardiac arrest were found. Overall, some trials reported an improved rate of ROSC following administration of thrombolytics, but there was no overall mortality reduction in any trial. There was, however, an increased risk of bleeding events following administration of a thrombolytic drug.

Conclusions:

Controlled trials demonstrate that there is a lack of benefit and potential harm in administering thrombolysis in an undifferentiated patient with cardiac arrest. However, the case we present provides evidence that fibrinolysis may benefit selected patients with cardiac arrest in whom PE is confirmed or in whom there is high index of suspicion of PE.

Good neurological recovery after cardiopulmonary resuscitation and thrombolysis in two old patients with pulmonary embolism

The use of thrombolysis as an emergency treatment for cardiac arrest (CA) due to massive pulmonary embolism (MPE) has been described. However, there are no reports of successful treatment of MPE-associated CA in patients over 77 years of age. We report two cases of successful cardiopulmonary resuscitation for an MPE-associated CA in two very old women (87 and 86 years of age). In both cases, typical signs of MPE were documented using emergency echocardiography, which showed an acute right ventricle enlargement and a paradoxical movement of the interventricular septum. Emergency thrombolysis was administered during resuscitation, which lasted 45 and 21 min, respectively. Despite old age and prolonged resuscitation efforts, both patients had good neurological recovery and one of them was alive and neurologically intact 1 year later. Thrombolysis is a potentially useful therapy in MPE-associated CA. A good neurological outcome can be obtained even in very old patients and after prolonged resuscitation.

Prospective multicenter evaluation of the pulmonary embolism rule-out criteria

BACKGROUND

Over-investigation of low-risk patients with suspected pulmonary embolism (PE) represents a growing problem. The combination of gestalt estimate of low suspicion for PE, together with the PE rule-out criteria [PERC(-): age < 50 years, pulse < 100 beats min(-1), SaO(2) >or= 95%, no hemoptysis, no estrogen use, no surgery/trauma requiring hospitalization within 4 weeks, no prior venous thromboembolism (VTE), and no unilateral leg swelling], may reduce speculative testing for PE. We hypothesized that low suspicion and PERC(-) would predict a post-test probability of VTE(+) or death below 2.0%.

METHODS

We enrolled outpatients with suspected PE in 13 emergency departments. Clinicians completed a 72-field, web-based data form at the time of test order. Low suspicion required a gestalt pretest probability estimate of <15%. The main outcome was the composite of image-proven VTE(+) or death from any cause within 45 days.

RESULTS

We enrolled 8138 patients, 85% of whom had a chief complaint of either dyspnea or chest pain. Clinicians reported a low suspicion for PE, together with PERC(-), in 1666 patients (20%). At initial testing and within 45 days, 561 patients (6.9%, 95% confidence interval 6.5-7.6) were VTE(+), and 56 others died. Among the low suspicion and PERC(-) patients, 15 were VTE(+) and one other patient died, yielding a false-negative rate of 16/1666 (1.0%, 0.6-1.6%). As a diagnostic test, low suspicion and PERC(-) had a sensitivity of 97.4% (95.8-98.5%) and a specificity of 21.9% (21.0-22.9%).

CONCLUSIONS

The combination of gestalt estimate of low suspicion for PE and PERC(-) reduces the probability of VTE to below 2% in about 20% of outpatients with suspected PE.

Empiric tenecteplase is associated with increased return of spontaneous circulation and short term survival in cardiac arrest patients unresponsive to standard interventions

BACKGROUND

Prospective and retrospective studies have shown that empiric use of fibrinolytic agents in sudden cardiac arrest is safe and may improve outcomes in sudden cardiac arrest. Use of fibrinolytic agents for this indication is increasing in response to these data.

METHODS

A prospective multicenter observational trial was performed in three emergency departments (EDs) to determine the proportion of patients that respond to empiric fibrinolysis with tenecteplase (TNK) after failing to respond to Advanced Cardiac Life Support (ACLS) measures. Cardiac arrest patients unresponsive to ACLS, who were given TNK by their treating physician, were enrolled in an outcome registry. Return of spontaneous circulation (ROSC), survival, complications, and neurological outcomes were recorded.

RESULTS

Fifty patients received TNK after a mean of 30min of cardiac arrest and eight doses of ACLS medications. One hundred and thirteen concurrent control patients received standard ACLS measures. ROSC occurred in 26% of TNK patients (95% confidence interval (CI) 16-40%) compared to 12.4% (95% CI 6.9-20%) among ACLS controls (p=.04); 12% (4.5-24%) of TNK patients survived to admission compared to none in the control group (p=.0007); 4% (0.5-14%) survived to 24h (p=NS); and 4% (0.5-14%) survived to hospital discharge (p=NS). All survivors had a good neurological outcome (Cerebral Performance Category (CPC) 1-2). One intracranial hemorrhage (ICH) occurred. No other significant bleeding complications were observed.

CONCLUSIONS

Empiric fibrinolysis with TNK in cardiac arrest is associated with increased ROSC and short term survival, and with survival to hospital discharge with good neurological function in patients who fail to respond to ACLS. Results may improve with earlier administration. Prospective controlled interventional trials are indicated to evaluate this promising new therapy.

Comparison of the unstructured clinician estimate of pretest probability for pulmonary embolism to the Canadian score and the Charlotte rule: a prospective observational study

OBJECTIVES

Clinical decision rules have been validated for estimation of pretest probability in patients with suspected pulmonary embolism (PE). However, many clinicians prefer to use clinical gestalt for this purpose. The authors compared the unstructured clinical estimate of pretest probability for PE with two clinical decision rules.

METHODS

This prospective, observational study was conducted from October 2001 to July 2004 at an urban academic emergency department with an annual census of 105,000. A total of 2,603 patients were enrolled; mean age (+/- SD) was 45 (+/- 16) years, and 70% were female. All patients were evaluated for PE using a previously published protocol, including D-dimer and alveolar dead space measurements, and selected use of pulmonary vascular imaging. All had 45-day follow-up. Interobserver agreement for each pretest probability estimation method was measured in a separate group of 154 patients.

RESULTS

The overall prevalence of PE was 5.8% (95% confidence interval [CI] = 4.9% to 6.8%). Most were deemed low risk for PE, including 69% by the unstructured estimate < 15%, 73% by the Canadian score < 2, and 88% by the Charlotte rule "safe." The corresponding prevalence of disease in each of these low-risk groups was 2.6%, 3.0%, and 4.2%. Weighted Cohen's kappa values were 0.60 (95% CI = 0.46 to 0.74) for the unstructured clinical estimate < 15%, 0.47 (95% CI = 0.33 to 0.61) for the Canadian score < 2, and 0.85 (95% CI = 0.69 to 1.0) for the Charlotte rule "safe."

CONCLUSIONS

The unstructured clinical estimate of low pretest probability for PE compares favorably with the Canadian score and the Charlotte rule. Interobserver agreement for the unstructured estimate is moderate.

Prospective use of a clinical decision rule to identify pulmonary embolism as likely cause of outpatient cardiac arrest

A clinical decision rule (CDR) derived retrospectively found that 57% of outpatients aged 65 years or less, with witnessed arrest+PEA had pulmonary embolism (PE) as cause of cardiac arrest. These retrospectively studied patients also had significant frequency of pre-arrest respiratory distress, altered mental status, and shock.

OBJECTIVES

(1) To test prospectively the feasibility and diagnostic accuracy of this CDR. (2) To test if the pre-arrest clinical triad of respiratory distress, altered mental status and shock predicts the presence of PE. All EMS personnel (N=204) in an urban EMS system and Emergency Department physicians (N=143) at 7 hospitals were included in the CDR and data collection.

INCLUSION CRITERIA

age 18-70, non-trauma, witnessed arrest, PEA as the first and primary rhythm. Exclusion: defibrillation before or more often than once after PEA. Criterion standards: autopsy or predefined cardiopulmonary imaging for PE. Over 21 months, 44 subjects were enrolled. Thirty-three subjects had a criterion standard (N=20 autopsy, 13-other criteria). 18/33 (54%; 95% CI 36-72%) had PE. Of the PE arrests, 88% were witnessed by EMS (N=8) or ED physicians (N=8), compared with 47% in the non-PE group (N=3 EMS and N=4 ED). Of the PE arrests, 83% had at least two of the three components of the triad versus 33% of the non-PE group (95% CI for difference 20-79). Mortality was 100% in the PE group. Analysis of the EMS cardiac arrest registry indicated that 65% of all patients served by the EMS system, age<or=70 recorded as having pre-hospital PEA arrest were enrolled during the study period.

CONCLUSIONS

We implemented successfully a CDR in a large, urban prehospital system to detect PE rapidly as most likely cause of cardiac arrest.

Impact of a rapid rule-out protocol for pulmonary embolism on the rate of screening, missed cases, and pulmonary vascular imaging in an urban US emergency department

STUDY OBJECTIVE

This study tests the hypothesis that implementation of a point-of-care emergency department (ED) protocol to rule out pulmonary embolism would increase the rate of evaluation without increasing the rate of pulmonary vascular imaging or ED length of stay and that less than 1.0% of patients with a negative protocol would have an adverse outcome.

METHODS

A baseline study was conducted on patients with suspected pulmonary embolism at an urban ED to establish baseline measurements performed when only pulmonary vascular imaging was available to rule out pulmonary embolism. The intervention protocol used pretest probability assessment, a whole-blood d -dimer assay, and an alveolar dead-space measurement to rule out pulmonary embolism. The main outcomes were diagnosis of venous thromboembolism or sudden unexpected death within 90 days.

RESULTS

During baseline, 453 of 61,322 patients (0.74%; 95% confidence interval [CI] 0.67% to 0.81%) underwent pulmonary vascular imaging, and 8% (95% CI 6% to 11%) of scan results were positive; 1.20% (95% CI 0.39% to 2.78%) of untreated discharged patients were anticoagulated for venous thromboembolism or died unexpectedly within 90 days. The median length of stay was 385 minutes. After intervention, 1,460 of 102,848 patients (1.42%; 95% CI 1.35% to 1.49%) were evaluated for pulmonary embolism. Seven hundred fifty-two patients had a negative protocol and 5 of 752 (0.66%; 95% CI 0.20% to 1.54%) had venous thromboembolism within 90 days, none with unexpected death. After intervention, the rate of pulmonary vascular imaging tended to decrease (0.64%; 95% CI 0.59% to 0.69%), and more scans (11%; 95% CI 9% to 14%) were read as positive; the length of stay decreased to 297 minutes.

CONCLUSION

A point-of-care pulmonary embolism rule-out protocol doubled the rate of screening for pulmonary embolism in the ED, had a false negative rate of less than 1.0%, did not increase the pulmonary vascular imaging rate, and decreased length of stay.

Pulmonary embolism: an unsuspected killer

The presentation of PE is often subtle and may mimic other diseases. Many pulmonary emboli invariably preclude diagnosis by their occult nature or by leading to rapid death from cardiopulmonary arrest. In patients who do manifest symptoms from PE, accurate diagnosis is essential. Often it is difficult to distinguish the vague symptoms of PE from other diagnoses, such as acute coronary syndrome, pneumonia, COPD, CHF,aortic dissection, myocarditis or pericarditis, pneumothorax, and musculo-skeletal or gastrointestinal causes. Regardless of the presentation, the most fundamental step in making the diagnosis of PE is first to consider it. Historical clues and risk factors should raise the clinician's suspicion.PE is an unsuspected killer with a nebulous presentation and high mortality. In all likelihood, PE will remain an elusive diagnosis despite advances in technology and a wealth of research. A high index of suspicion is required, but no amount of suspicion would eliminate all missed cases. Patients with significant underlying cardiopulmonary disease seem to be the most challenging. Patients with significant comorbidity have poor reserve and are likely to have poor outcomes, especially if the diagnosis is not made and anticoagulation is not initiated early. Controversy exists over the best diagnostic approach to PE. A battery of diagnostic studies is available, with few providing definitive answers. Studies such as CT may be helpful at some institutions but offer poor predictive value at others. Other diagnostic tests are not universally available. It is hoped that further research and improvements in current diagnostic modalities will clear some of the current confusion and controversy of this ubiquitous and deadly disease.

Prehospital cardiac arrest and the adverse effect of male gender, but not age, on outcome

OBJECTIVE

To analyze the incidence and outcome of prehospital cardiac arrest as it correlated to gender and age as a secondary end point in an interventional clinical trial.

METHODS

This prospective, randomized, double-blinded clinical intervention trial enrolled 874 prehospital cardiopulmonary arrest patients encountered by prehospital urban, suburban, and rural regional emergency medical service (EMS) areas. This trial evaluated outcome and profiled demographic predictors of cardiac arrest patients refractory to defibrillation with intravenous access who underwent standard advanced cardiac life support (ACLS) intervention and empiric early administration of bicarbonate. Survival was measured to the emergency department (ED), and data analysis used chi-square with Pearson correlation.

RESULTS

The overall survival rate was 14.2%. There was no age correlate to survival, with an average age of 67.4 for both groups. Male patients had a 2.4-fold increased incidence (70.7 vs. 29.3%, p = 0.001) of arrest, which was associated with a 60% increase in mortality (19.6% vs. 11.8, p = 0.004) compared with women. The risk of unfavorable outcome was increased for men (OR 1.826, 95% CI 1.182-2.821; RR 1.097, 95% CI 1.025-1.180) on univariate analysis. There appeared to be no intergroup differences found with other historical variables, such as the presence of myocardial infarction (MI), hypertension (HTN), diabetes mellitus (DM), congestive heart failure (CHF), and chronic obstructive pulmonary disease (COPD), which were analyzed. However, HTN was found more commonly (2.2 times) in men (69.1 vs. 30.9%) than in women but did not correlate with survival.

CONCLUSIONS

Male gender, but not age, is associated with both an increased incidence and a worsened outcome in prehospital cardiac arrest.

End tidal CO(2) is reduced during hypotension and cardiac arrest in a rat model of massive pulmonary embolism

BACKGROUND

We investigated the effect of massive pulmonary embolism (MPE) on end tidal CO(2) (etCO(2)) and tested two hypotheses: (1) that etCO(2) can distinguish massive PE from hemorrhagic shock and (2) that PE with cardiac arrest reduces etCO(2) during resuscitation to a greater extent than arrhythmic cardiac arrest.

METHODS

Anesthetized, mechanically ventilated rats (N=10 per group), were subjected to either graded PE (latex microspheres), or graded hemorrhagic shock to produce a final mean arterial blood pressure, (MAP) of 40 mmHg; a third group was subjected to surgical/anesthetic control conditions. Cardiac arrest was induced by the following methods: intravenous injection of a large bolus of microspheres in the PE group, aortic puncture in the hemorrhage group, and intravenous tetrodotoxin (TTX) to produce arrhythmic cardiac arrest in the control group.

RESULTS

At a MAP of 40 mmHg, etCO(2) was significantly decreased in the PE group (18.3+/-1.9 torr) compared with both the hemorrhage (24.3+/-1.3) and the control group (35.0+/-1.3 torr; ANOVA P<0.001). The decreased etCO(2) occurred coincident with an increase in alveolar dead space fraction in the PE group. In the first minute of ventilation after cardiac arrest, the etCO(2) was significantly decreased in the PE group (6.5+/-0.9) versus both hemorrhage (16.5+/-1.1) and TTX (34.2+/-2.4 torr).

CONCLUSIONS

Massive PE with shock decreases the etCO(2) and increases the dead space fraction to a greater extent than hemorrhagic shock at the same MAP. Cardiac arrest from PE is associated with extremely low etCO(2) readings during CPR.

Identification of prearrest clinical factors associated with outpatient fatal pulmonary embolism

Massive pulmonary embolism (MPE) is an important cause of outpatient sudden death, and description of these patients is critical for identification and treatment.

OBJECTIVE

To test whether MPE patients can be distinguished from patients suffering sudden death from other causes based on clinical, demographic, and historical data. The hypothesis was that MPE cases would be more likely to manifest components of a clinical triad of 1) overt dyspnea, 2) alteration of mental status or syncope, and 3) shock index (pulse divided by systolic blood pressure) >0.8.

METHODS

Retrospective case-control study of medical examiner data from 1992 to 1999 including all patients with nontraumatic death, aged 18-65 years, transported to an emergency department, with autopsy-determined cause of death. Analysis was done by 95% confidence interval (95% CI) for difference in proportions and multivariate logistic regression for odds ratios.

RESULTS

The MPE patients (n = 37) were younger than the control subjects (n = 347) (40.2 vs 46.5 years, unpaired t-test p < 0.001). At least two of the three components of the triad were present in 56.8% of MPE cases vs 3.5% of controls (95% CI for difference in proportions = 37.3% to 68.0%). Significant variables (and odds ratios) for MPE after multivariate analysis included: dyspnea (13.8), shock index >0.8 (23.6), immobilization or fracture (14.6), seen by a physician within two weeks (5.1), and African American female status (6.4).

CONCLUSIONS

Patients in this community with fatal MPE were young with risk factors for pulmonary embolism, and commonly manifested components of a triad including: dyspnea, alteration of mental status/syncope, and shock prior to death.