A simplified and structured teaching tool for the evaluation and management of pulseless electrical activity

Association between QRS characteristics in pulseless electrical activity and survival outcome in cardiac arrest patients: A systematic review and meta-analysis

Objective: Recent studies have shown inconsistent results regarding the association between QRS characteristics and survival outcomes in patients with cardiac arrest and pulseless electrical activity (PEA) rhythms. This meta-analysis aimed to identify the usefulness of QRS width and frequency as prognostic tools for outcomes in patients with cardiac arrest and PEA rhythm.Methods: Extensive searches were conducted using Medline, Embase, and the Cochrane Library to find articles published from database inception to 4 June 2023. Studies that assessed the association between the QRS characteristics of cardiac arrest patients with PEA rhythm and survival outcomes were included. The Newcastle-Ottawa Scale was used to assess the methodological quality of the included studies.Results: A total of 9,727 patients from seven observational studies were included in this systematic review and meta-analysis. The wide QRS group (QRS ≥ 120 ms) was associated with significantly higher odds of mortality than the narrow QRS group (QRS < 120 ms) (odds ratio (OR) = 1.86, 95% confidence interval (CI) = 1.11-3.11, I2 = 58%). The pooled OR for mortality was significantly higher in patients with a QRS frequency of < 60/min than in those with a QRS frequency of ≥ 60/min (OR = 1.90, 95% CI = 1.19-3.02, I2 = 65%).Conclusions: Wide QRS width or low QRS frequency is associated with increased odds of mortality in patients with PEA cardiac arrest. These findings may be beneficial to guide the disposition of cardiac arrest patients with PEA during resuscitation.

Common ECG interpretation software mistakes Part II: Computer errors that hide diagnostic clues

Electrocardiogram (ECG) interpretation software mistakes can lead to incorrect diagnoses and inappropriate treatments. Occasionally, however, repetitive and consistent computer errors may hide important clues for correct diagnoses that otherwise could have been missed. We present a collection of a few common and clinically important such peculiarities, and provide tools on how to prove or disprove the suspected diagnosis. In addition to the illustrations in print, an online supplement (OS) shows more examples of the discussed phenomena. In each ECG, the original computer interpretations were enlarged for legibility.

High accuracy distinction of shockable and non-shockable arrhythmias in abnormal classes through wavelet transform with pseudo differential like operators

Arrhythmia is an abnormal rhythm of the heart which leads to sudden death. Among these arrhythmias, some are shockable, and some are non-shockable arrhythmias with external defibrillation. The automated external defibrillator (AED) is used as the automated arrhythmia diagnosis system and requires an accurate and rapid decision to increase the survival rate. Therefore, a precise and quick decision by the AED has become essential in improving the survival rate. This paper presents an arrhythmia diagnosis system for the AED by engineering methods and generalized function theories. In the arrhythmia diagnosis system, the proposed wavelet transform with pseudo-differential like operators-based method effectively generates a distinguishable scalogram for the shockable and non-shockable arrhythmia in the abnormal class signals, which leads to the decision algorithm getting the best distinction. Then, a new quality parameter is introduced to get more details by quantizing the statistical features on the scalogram. Finally, design a simple AED shock and non-shock advice method by following this information to improve the precision and rapid decision. Here, an adequate topology (metric function) is adopted to the space of the scatter plot, where we can give different scales to select the best area of the scatter plot for the test sample. As a consequence, the proposed decision method gives the highest accuracy and rapid decision between shockable and non-shockable arrhythmias. The proposed arrhythmia diagnosis system increases the accuracy to 97.98%, with a gain of 11.75% compared to the conventional approach in the abnormal class signals. Therefore, the proposed method contributes an additional 11.75% possibility for increasing the survival rate. The proposed arrhythmia diagnosis system is general and could be applied to distinguish different arrhythmia-based applications. Also, each contribution could be used independently in various applications.

Computer-Estimated Heart Rate vs True Heart Rate-Be Aware of the Software

This case report describes a patient in their 60s with gastrointestinal bleeding and shock with heart rate overcounting by software indicating severe hyperkalemia.

How senior paramedics decide to cease resuscitation in pulseless electrical activity out of hospital cardiac arrest: a mixed methods study

BACKGROUND

Evidenced-based guidelines on when to cease resuscitation for pulseless electrical activity are limited and support for paramedics typically defaults to the senior clinician. Senior clinicians include paramedics employed to work beyond the scope of clinical guidelines as there may be a point at which it is reasonable to cease resuscitation. To support these decisions, one ambulance service has applied a locally derived cessation of resuscitation checklist. This study aimed to describe the patient, clinical and system factors and examine senior clinician experiences when ceasing resuscitation for pulseless electrical activity.

DESIGN AND METHODS

An explanatory sequential mixed method study was conducted in one ambulance service in the South West of England. A consecutive sample of checklist data for adult pulseless electrical activity were retrieved from 1st December 2015 to 31st December 2018. Unexpected results which required exploration were identified and developed into semi-structured interview questions. A purposive sample of senior clinicians who ceased resuscitation and applied the checklist were interviewed. Content framework analysis was applied to the qualitative findings.

RESULTS

Senior clinicians ceased resuscitation for 50 patients in the presence of factors known to optimise survival: Witnessed cardiac arrest (n = 37, 74%), bystander resuscitation (n = 30, 60%), defibrillation (n = 22, 44%), return of spontaneous circulation (n = 8, 16%). Significant association was found between witnessed cardiac arrest and bystander resuscitation (p = .00). Six senior clinicians were interviewed, and analysis resulted in four themes: defining resuscitation futility, the impact of ceasing resuscitation, conflicting views and clinical decision tools. In the local context, senior clinicians applied their clinical judgement to balance survivability. Multiple factors were considered as the decision to cease resuscitation was not always clear. Senior clinicians deviated from the checklist when the patient was perceived as non-survivable.

CONCLUSION

Senior clinicians applied clinical judgement to assess patients as non-survivable or when continued resuscitation was considered harmful with no patient benefit. Senior clinicians perceived pre-existing factors with duration of resuscitation and clinical factors known to optimise patient survival. Future practice could look beyond a set criteria in which to cease resuscitation, however, it would be helpful to investigate the value or threshold of factors associated with patient outcome.

Multimodal Algorithms for the Classification of Circulation States During Out-of-Hospital Cardiac Arrest

GOAL

Identifying the circulation state during out-of-hospital cardiac arrest (OHCA) is essential to determine what life-saving therapies to apply. Currently algorithms discriminate circulation (pulsed rhythms, PR) from no circulation (pulseless electrical activity, PEA), but PEA can be classified into true (TPEA) and pseudo (PPEA) depending on cardiac contractility. This study introduces multi-class algorithms to automatically determine circulation states during OHCA using the signals available in defibrillators.

METHODS

A cohort of 60 OHCA cases were used to extract a dataset of 2506 5-s segments, labeled as PR (1463), PPEA (364) and TPEA (679) using the invasive blood pressure, experimentally recorded through a radial/femoral cannulation. A multimodal algorithm using features obtained from the electrocardiogram, the thoracic impedance and the capnogram was designed. A random forest model was trained to discriminate three (TPEA/PPEA/PR) and two (PEA/PR) circulation states. The models were evaluated using repeated patient-wise 5-fold cross-validation, with the unweighted mean of sensitivities (UMS) and F ₁-score as performance metrics.

RESULTS

The best model for 3-class had a median (interquartile range, IQR) UMS and F ₁ of 69.0% (68.0-70.1) and 61.7% (61.0-62.5), respectively. The best two class classifier had median (IQR) UMS and F ₁ of 83.9% (82.9-84.5) and 76.2% (75.0-76.9), outperforming all previous proposals in over 3-points in UMS.

CONCLUSIONS

The first multiclass OHCA circulation state classifier was demonstrated. The method improved previous algorithms for binary pulse/no-pulse decisions.

SIGNIFICANCE

Automatic multiclass circulation state classification during OHCA could contribute to improve cardiac arrest therapy and improve survival rates.

Association between wide QRS pulseless electrical activity and hyperkalemia in cardiac arrest patients

AIM

We evaluated the relationship between hyperkalemia and wide QRS complex in patients with pulseless electrical activity (PEA) cardiac arrest.

METHODS

This was a single-center, retrospective observational study of patients over the age of 18 treated for cardiac arrest at a tertiary referral hospital whose initial electrocardiogram rhythm was PEA from February 2010 to December 2019. Wide QRS PEA was defined as a QRS interval of 120 ms or more. Hyperkalemia was defined as serum potassium level > 5.5 mmol/L. The primary outcome was hyperkalemia. Multivariable logistic regression analysis was used to evaluate the relationship between wide QRS and hyperkalemia.

RESULTS

Among 617 patients, we analyzed 111 episodes in the wide QRS group and 506 episodes in the narrow QRS group. The potassium level in the wide QRS group was significantly higher than in the narrow QRS group (5.4 mmol/L, IQR 4.4-6.7 vs. 4.6 mmol/L, IQR 4.0-5.6, P < 0.001). Among all patients, 49.6% (n = 55/111) in the wide QRS group had hyperkalemia, which was significantly higher than the 26.7% (n = 135/506) in the narrow QRS group (P < 0.001). In multivariable logistic regression analysis, wide QRS PEA was significantly associated with hyperkalemia (odds ratio = 2.86, 95% confidence interval: 1.80-4.53, P < 0.001).

CONCLUSIONS

Wide QRS PEA as an initial cardiac rhythm was significantly associated with hyperkalemia in cardiac arrest patients.

Pulseless Electrical Activity: Detection of Underlying Causes in a Prehospital Setting

The proportion of out-of-hospital cardiac arrests (OHCAs) with pulseless electrical activity (PEA) as initial rhythm is increasing. PEA should be managed by identifying the underlying cause of the arrest and treating it accordingly. This often poses a challenge in the chaotic prehospital environment with only limited resources available. The aim of this study was to review the diagnostic tools available in a prehospital setting, and their interpretation during cardiac arrest (CA) with PEA as initial rhythm. A systematic literature search of the PubMed database was performed. Articles were assessed for eligibility by title, abstract, and full text. Ultrasonography has become a great asset in detecting underlying causes, and a variety of protocols have been proposed. There are currently no studies comparing these protocols regarding their feasibility and their effect on patient survival. Further research concerning the relationship between electrocardiogram characteristics and underlying causes is required. Limited evidence suggests a role for point-of-care testing in detecting hyperkalemia and a role for capnography in the diagnosis of asphyxia CA. Multiple studies describe a prognostic potential. Although evidence about the prognostic potential of cerebral oximetry in OHCA is accumulating, its diagnostic potential is still unknown. In the management of OHCA, anamnestic and clinical information remains the initial source of information in search for an underlying cause. Ultrasonographic evaluation should be performed subsequently, both for detecting an underlying cause and discriminating between true PEA and pseudo PEA. Comparative studies are required to identify the best ultrasonographic protocol, which can be included in resuscitation guidelines.

Patterns in continuous pulse oximetry data prior to pulseless electrical activity arrest in the general care setting

The study objective was to understand if features derived from continuous pulse oximetry data can provide advanced warning of pulseless electrical activity arrest in the general care inpatient setting. Retrospective analysis of SpO2 and pulse rate data derived from continuous pulse oximetry was performed for pulseless electrical activity (n = 38) and control (n = 42) patient cohorts. Measures of central tendency and variation over time intervals ranging from 1 min to 1 h were used for inter- and intra-group comparisons. Logistic regression was applied to understand ability of features to predict pulseless electrical activity in future time intervals. Overall, the pulseless electrical activity arrest group tended to have lower mean SpO2 and higher mean pulse rate values than the control group. SpO2 and pulse rate variability was higher in the pulseless electrical activity arrest cohort. Changes in variability were observed beginning several hours prior to the rescue event. Up to 20 min before rescue events, pulse rate features were significantly different from feature values for the preceding 30-min interval (> 10% difference in mean, > 46% difference in range). Similar results were found for SpO2 features 10 min before the event (> 4% difference in mean, > 60% difference in range). There is a significant difference in SpO2 and pulse rate features derived from continuous pulse oximetry between pulseless electrical activity and control groups. Integration of automated feature calculation and clinician notification into clinical monitoring and information systems may increase patient safety by supporting early detection of such events.

Non-perfusing cardiac rhythms in asphyxiated newborn piglets

Aim

We recently demonstrated that asphyxiated piglets commonly had bradycardia displayed on electrocardiography (ECG) while no carotid blood flow (CBF) or audible heart sounds could be detected. Such pulseless electrical activity (PEA) in newborn infants has not previously been thoroughly described. The aim of this study was to further investigate the occurrence of non-perfusing cardiac rhythms in asphyxiated piglets and the potential implications for the success of cardiopulmonary resuscitation (CPR) and short-term survival.

Methods

Neonatal piglets (1–4 days, 1.7–2.4kg) had their right common carotid artery exposed and enclosed with a real-time ultrasonic flow probe. Heart rate (HR) was continuously measured and recorded using ECG. This allowed simultaneous monitoring of HR via ECG and CBF. The piglets were asphyxiated until cardiac arrest, defined as no CBF and no audible beat upon precordial auscultation. CPR was performed until return of spontaneous circulation (ROSC, defined as a HR ≥100 bpm). ECG traces were retrospectively assessed.

Results

Nine out of 21 piglets (43%) had QRS-complexes on their ECG while no CBF and no audible heart sounds could be detected. Five (56%) of the piglets with PEA and 12/12 (100%) piglets with asystole at cardiac arrest obtained ROSC (p = 0.02). Thirty-three per cent of the piglets with PEA versus 58% with asystole survived to 4 hours post-ROSC (p = 0.39).

Conclusion

Cardiac arrest in the presence of a non-perfusing cardiac rhythm on ECG is common in asphyxiated piglets. Clinical arrest in the presence of a non-perfusing cardiac rhythm on ECG may reduce the success of CPR.

Critical Care of the Post-Cardiac Arrest Patient

The post-cardiac arrest syndrome is a highly inflammatory state characterized by organ dysfunction, systemic ischemia and reperfusion injury, and persistent precipitating pathology. Early critical care should focus on identifying and treating arrest etiology and minimizing further injury to the brain and other organs by optimizing perfusion, oxygenation, ventilation, and temperature. Patients should be treated with targeted temperature management, although the exact temperature goal is not clear. No earlier than 72 hours after rewarming, prognostication using a multimodal approach should inform discussions with families regarding likely neurologic outcome.

The predictive value of bedside ultrasound to restore spontaneous circulation in patients with pulseless electrical activity: A systematic review and meta-analysis

Background

The prognosis of pulseless electrical activity is dismal. However, it is still challengable to decide when to terminate or continue resuscitation efforts. The aim of this study was to determine whether the use of bedside ultrasound (US) could predict the restoration of spontaneous circulation (ROSC) in patients with pulseless electrical activity (PEA) through the identification of cardiac activity.

Methods

This was a systematic review and meta-analysis of studies that used US to predict ROSC. A search of electronic databases (Cochrane Central, MEDLINE, EMBASE) was conducted up to June 2017, and the assessment of study quality was performed with the Newcastle-Ottawa Scale. Statistical analysis was performed with Review Manager 5.3 and Stata 12.

Results

Eleven studies that enrolled a total of 777 PEA patients were included. A total of 230 patients experienced ROSC. Of these, 188 had sonographically identified cardiac activity (pseudo-PEA). A meta-analysis showed that PEA patients with cardiac activity on US were more likely to obtain ROSC compared to those with cardiac standstill: risk ratio (RR) = 4.35 (95% confidence interval [CI], 2.20–8.63; p<0,00001) with significant statistical heterogeneity (I² = 60%). Subgroup analyses were conducted: US evaluation using only on the subxiphoid view: RR = 1.99 (95% CI, 0.79–5.02; p = 0.15); evaluation using various views: RR = 4.09 (95% CI,2.70–6.02; p<0.00001).

Conclusions

In cardiac arrest patients who present with PEA, bedside US has an important role in predicting ROSC. The presence of cardiac activity in PEA patients may encourage more aggressive resuscitation.

Electrocardiography vs. Auscultation to Assess Heart Rate During Cardiac Arrest With Pulseless Electrical Activity in Newborn Infants

Background: In 2015, the neonatal resuscitation guidelines incorporated the use of electrocardiography (ECG) to monitor heart rate of newborns. However, previous studies have indicated that cardiac arrest with pulseless electrical activity rhythm (PEA) may occur in the delivery room, rendering this method problematic. Objective: To evaluate the accuracy of ECG and auscultation to assess heart rate during PEA. Methods: A total of 45 piglets (age 1-3 days, weight 1.7-2.3 kg) were exposed to 30 min normocapnic alveolar hypoxia followed by asphyxia until asystole, achieved by disconnecting the ventilator and clamping the endotracheal tube. During asphyxia, heart rate (HR) was assess using auscultation, ECG, and carotid blood flow (CBF). At the time of asystole (defined as zero CBF) HR auscultated using a neonatal/infant stethoscope was compared to ECG traces. Results: The median (IQR) duration of asphyxia was 325 (200-491) s. In 8 (18%) piglets, CBF, ECG, and auscultation identified asystole. In 22 (49%) piglets no CBF and no audible heart sounds, were observed, while ECG displayed a HR ranging from 17 to 75/min. Fifteen (33%) piglets remained bradycardic (defined as HR of < 100/min) after 10 min of asphyxia, which was identified by CBF, ECG, and auscultation. The overall accuracy of ECG and auscultation in the detection of HR were 51 and 80%, respectively (p = 0.004). Conclusion: In cases with PEA ECG is not superior in correctly identifying HR in newborn piglets.

Echocardiography in cardiac arrest: An emergency medicine review

INTRODUCTION

Cardiac arrest management primarily focuses on optimal chest compressions and early defibrillation for shockable cardiac rhythms. Non-shockable rhythms such as pulseless electrical activity (PEA) and asystole present challenges in management. Point-of-care ultrasound (POCUS) in cardiac arrest is promising.

OBJECTIVES

This review provides a focused assessment of POCUS in cardiac arrest, with an overview of transthoracic (TTE) and transesophageal echocardiogram (TEE), uses in arrest, and literature support.

DISCUSSION

Cardiac arrest can be distinguished between shockable and non-shockable rhythms, with management varying based on the rhythm. POCUS provides a diagnostic and prognostic tool in the emergency department (ED), which may improve accuracy in clinical decision-making. Several protocols incorporate POCUS based on different cardiac views. TTE includes parasternal long axis, parasternal short axis, apical 4-chamber, and subxiphoid views, which may be used in cardiac arrest for diagnosis of underlying cause and potential prognostication. TEE is conducted by inserting the probe into the esophagus of intubated patients, with several studies evaluating its use in cardiac arrest. It is associated with few adverse effects, while allowing continued compressions (and evaluation of those compressions) and not interrupting resuscitation efforts.

CONCLUSIONS

POCUS is a valuable diagnostic and prognostic tool in cardiac arrest, with recent literature supporting its diagnostic ability. TTE can guide resuscitation efforts dependent on the rhythm, though TTE should not interrupt other resuscitation measures. TEE can be useful during arrest, but further studies based in the ED are needed.

Improving Survival From Cardiac Arrest: A Review of Contemporary Practice and Challenges

Cardiac arrest is a common and lethal condition frequently encountered by emergency medicine providers. Resuscitation of persons after cardiac arrest remains challenging, and outcomes remain poor overall. Successful resuscitation hinges on timely, high-quality cardiopulmonary resuscitation. The optimal method of providing chest compressions and ventilator support during cardiac arrest remains uncertain. Prompt and effective defibrillation of ventricular arrhythmias is one of the few effective therapies available for treatment of cardiac arrest. Despite numerous studies during several decades, no specific drug delivered during cardiac arrest has been shown to improve neurologically intact survival after cardiac arrest. Extracorporeal circulation can rescue a minority of highly selected patients with refractory cardiac arrest. Current management of pulseless electrical activity is associated with poor outcomes, but it is hoped that a more targeted diagnostic approach based on electrocardiography and bedside cardiac ultrasonography may improve survival. The evolution of postresuscitation care appears to have improved cardiac arrest outcomes in patients who are successfully resuscitated. The initial approach to early stabilization includes standard measures, such as support of pulmonary function, hemodynamic stabilization, and rapid diagnostic assessment. Coronary angiography is often indicated because of the high frequency of unstable coronary artery disease in comatose survivors of cardiac arrest and should be performed early after resuscitation. Optimizing and standardizing our current approach to cardiac arrest resuscitation and postresuscitation care will be essential for developing strategies for improving survival after cardiac arrest.

ECG patterns in early pulseless electrical activity-Associations with aetiology and survival of in-hospital cardiac arrest

INTRODUCTION

Pulseless electrical activity (PEA) is an increasingly common presentation in cardiac arrest. The aim of this study was to investigate possible associations between early ECG patterns in PEA and the underlying causes and survival of in-hospital cardiac arrest (IHCA).

METHODS

Prospectively observed episodes of IHCA presenting as PEA between January 2009 and august 2013, with a reliable cause of arrest and corresponding defibrillator ECG recordings, were analysed. QRS width, QT interval, Bazett's corrected QT interval, presence of P waves and heart rate (HR) was determined. QRS width and HR were considered to be normal below 120ms and within 60-100 cardiac cycles per minute, respectively.

RESULTS

Fifty-one episodes fulfilled the inclusion criteria. The defibrillator was attached after a median of one minute (75th percentile; 3min) after the onset of arrest. Ninety percent (46/51) had widened QRS complexes, 63% (32/51) were defined as 'wide-slow' due to QRS-widened bradycardia, and only 6% (3/51) episodes were categorized as normal. No unique cause-specific ECG pattern could be identified. Further 7 episodes with a corresponding defibrillator file, but without a reliable cause, were included in analysis of survival. Abnormal ECG patterns were seen in all survivors. None of the patients with 'normal' PEA survived.

CONCLUSION

Abnormal ECG patterns were frequent at the early stage of in-hospital PEA. No unique patterns were associated with the underlying causes or survival.

Focused Cardiac Ultrasound Diagnosis of Cor Triatriatum Sinistrum in Pediatric Cardiac Arrest

Cardiac arrest in the adolescent population secondary to congenital heart disease (CHD) is rare. Focused cardiac ultrasound (FoCUS) in the emergency department (ED) can yield important clinical information, aid in resuscitative efforts during cardiac arrest and is commonly integrated into the evaluation of patients with pulseless electrical activity (PEA). We report a case of pediatric cardiac arrest in which FoCUS was used to diagnose a critical CHD known as cor triatriatum sinistrum as the likely cause for PEA cardiac arrest and help direct ED resuscitation.

Cardiac arrest with initial arrest rhythm of pulseless electrical activity: do rhythm characteristics correlate with outcome?

OBJECTIVES

Cardiac arrest is a leading cause of death in the United States, with pulseless electrical activity (PEA) as a common initial arrest rhythm. We sought to determine if rate of electrical activity and QRS width correlate with survival in patients who present with PEA out-of-hospital cardiac arrest.

METHODS AND RESULTS

This is a retrospective review of patients with PEA out-of-hospital cardiac arrest with first documented cardiac rhythm of PEA from January 2010 to September 2013. Demographic, arrest and initial rhythm characteristics, and patient outcome were abstracted via systematic chart review. The initial 20 seconds of each rhythm strip were used to ascertain electrical rate and QRS width. Primary outcome was survival to hospital discharge. Four hundred fourteen patients were eligible for the study. One hundred fifty-two patients did not have sufficient data for analysis. Two hundred sixty-two patients were included in the final analysis with mean age, 66 years. There were 23 (8.8%) survivors and 17 (6.5%) neurologically intact survivors. Mean heart rate was 58 (confidence interval, 54-63) beats per minute, and mean QRS interval was 100 (confidence interval, 95-106) milliseconds. Twenty-nine point seven percent of patients had wide QRS complexes, and 70.3% were narrow. There was no difference in survival in patients based on heart rate (13.1% vs 7.4%, P = .16) or QRS interval (8.7% vs 7.7%, P = .79).

CONCLUSIONS

In this single emergency medical services agency study, neither PEA electrical rate nor QRS width correlated with survival or neurologic outcome.

Traumatic Tension Pneumothorax as a Cause of ICD Failure: A Case Report and Review of the Literature

Background. Tension pneumothorax can infrequently cause ventricular arrhythmias and increase the threshold of defibrillation. It should be suspected whenever there is difficulty in defibrillation for a ventricular arrhythmia. Purpose. To report a case of traumatic tension pneumothorax leading to ventricular tachycardia and causing defibrillator failure. Case. A 65-year-old African-American female was brought in to our emergency department complaining of dyspnea after being forced down by cops. She had history of mitral valve replacement for severe mitral regurgitation and biventricular implantable cardioverter defibrillator inserted for nonischemic cardiomyopathy. Shortly after arrival, she developed sustained ventricular tachycardia, causing repetitive unsuccessful ICD shocks. She was intubated and ventricular tachycardia resolved with amiodarone. Chest radiograph revealed large left sided tension pneumothorax which was promptly drained. The patient was treated for congestive heart failure; she was extubated on the third day of admission, and the chest tube was removed. Conclusion. Prompt recognition of tension pneumothorax is essential, by maintaining a high index of suspicion in patients with an increased defibrillation threshold causing ineffective defibrillations.