Breathing patterns during cardiac arrest

An Approach to Caring for Patients and Family of Patients Dying in the ICU

TOPIC IMPORTANCE

Death is common in the ICU and often occurs after a decision to withhold or withdraw life-sustaining therapies. Care of the dying is a core skill for ICU clinicians, requiring expert communication, primarily with family of critically ill patients.

REVIEW FINDINGS

Limited high-quality evidence supports specific practices related to the care of dying patients in the ICU; thus, many of the recommendations that exist are based on expert opinion. Value exists in sharing a practical approach to caring for patients during the dying process, including topics to be addressed with family members, rationales for recommended care, and strategies for implementing comfort measures only. Through dedicated preparation and planning, clinicians can help family members navigate this intense experience.

SUMMARY

After a decision had been made to discontinue life-sustaining therapies, family members need to be given a clear description of comfort measures only and provided with additional detail about what it entails, including therapies or interventions to be discontinued, monitoring during the dying process, and common features of the dying process. Order sets can be a valuable resource for ensuring that adequate analgesia and sedation are available and the care plan is enacted properly. To achieve a good death for patients, a collaborative effort among members of the care team is essential.

Agonal breathing upon hospital arrival as a prognostic factor in patients experiencing out-of-hospital cardiac arrest

Background

Agonal breathing is a relatively common symptom that follows cardiac arrest when the brainstem function is preserved. Agonal breathing is associated with favorable survival in patients experiencing out-of-hospital cardiac arrest (OHCA). While previous studies focused on agonal breathing observed in the pre-hospital setting for all study subjects, we focused on agonal breathing observed upon hospital arrival. In this multicenter prospective study, we aimed to assess the prognosis of patients exhibiting agonal breathing upon hospital arrival were compared. We hypothesized that agonal breathing at hospital arrival would be associated with favorable neurological outcomes among patients with OHCA.

Methods

The data on incidence of agonal breathing were prospectively collected for all evaluable participants in a multicenter, observational study in Japan (SOS-KANTO [Survey of Survivors after Out-of-Hospital Cardiac Arrest in Kanto Area] 2017 Study). Groups with and without agonal breathing were compared upon hospital arrival. Propensity-score with inverse probability of treatment weighting (IPTW) analysis was performed to adjust for confounding factors. The primary outcome was a favorable neurological outcome (Cerebral Performance Category 1-2) at 1 month.

Results

A total of 6,457 participants out of the 9,909 registered in SOS-KANTO 2017 (in which 42 facilities participated) were selected for the current study. There were 128 patients (2.0%) in the with-agonal breathing group and 6,329 (98.0%) in the withoutagonal breathing group. The primary outcome was 1.1% in the with-agonal breathing group and 0.6% in the without-agonal breathing group (risk difference, 0.55; 95% confidence interval, 0.23-0.87) after IPTW analysis.

Conclusion

In this multicenter prospective study, agonal breathing at hospital arrival was significantly associated with better neurological outcomes and increased survival at 1 month. Thus, agonal breathing at hospital arrival may be a useful prognostic predictor for patients experiencing OHCA.

Severe Hypoxemia Prevents Spontaneous and Naloxone-induced Breathing Recovery after Fentanyl Overdose in Awake and Sedated Rats

BACKGROUND

As severe acute hypoxemia produces a rapid inhibition of the respiratory neuronal activity through a nonopioid mechanism, we have investigated in adult rats the effects of hypoxemia after fentanyl overdose-induced apnea on (1) autoresuscitation and (2) the antidotal effects of naloxone.

METHODS

In nonsedated rats, the breath-by-breath ventilatory and pulmonary gas exchange response to fentanyl overdose (300 µg · kg · min iv in 1 min) was determined in an open flow plethysmograph. The effects of inhaling air (nine rats) or a hypoxic mixture (fractional inspired oxygen tension between 7.3 and 11.3%, eight rats) on the ability to recover a spontaneous breathing rhythm and on the effects of naloxone (2 mg · kg) were investigated. In addition, arterial blood gases, arterial blood pressure, ventilation, and pulmonary gas exchange were determined in spontaneously breathing tracheostomized urethane-anesthetized rats in response to (1) fentanyl-induced hypoventilation (7 rats), (2) fentanyl-induced apnea (10 rats) in air and hyperoxia, and (3) isolated anoxic exposure (4 rats). Data are expressed as median and range.

RESULTS

In air-breathing nonsedated rats, fentanyl produced an apnea within 14 s (12 to 29 s). A spontaneous rhythmic activity always resumed after 85.4 s (33 to 141 s) consisting of a persistent low tidal volume and slow frequency rhythmic activity that rescued all animals. Naloxone, 10 min later, immediately restored the baseline level of ventilation. At fractional inspired oxygen tension less than 10%, fentanyl-induced apnea was irreversible despite a transient gasping pattern; the administration of naloxone had no effects. In sedated rats, when PaO2 reached 16 mmHg during fentanyl-induced apnea, no spontaneous recovery of breathing occurred and naloxone had no rescuing effect, despite circulation being maintained.

CONCLUSIONS

Hypoxia-induced ventilatory depression during fentanyl induced apnea (1) opposes the spontaneous emergence of a respiratory rhythm, which would have rescued the animals otherwise, and (2) prevents the effects of high dose naloxone.

Prognostic value of gasping for short and long outcomes during out-of-hospital cardiac arrest: an updated systematic review and meta-analysis

Objective

We systematically reviewed the literature to investigate whether gasping could predict short and long outcomes in patients with out of hospital cardiac arrest (OHCA).

Methods

PubMed, Embase, and Cochrane Library were searched for observational studies regarding the prognostic effect of gasping on short and long outcomes in adults with OHCA. The primary outcome was return of spontaneous circulation (ROSC). The secondary outcomes were favorable neurological outcome at discharge or at 30 days after cardiac arrest;long term (≥6 months) survival; initial shockable rhythm.The Mantel-Haenszel method with random-effects model was used to calculate pooled relative risks (RRs) and 95% confidence intervals (CIs).

Results

Five studies (six cohorts) were included in the final analysis. In the pooled analysis, gasping was not only associated with a significant increase in ROSC (RR, 1.87; 95% CI, 1.64–2.13; I² = 70%), but also a high likelihood of favorable neurological outcomes (RR, 3.79; 95% CI, 1.86–7.73), long-term survival (RR, 3.46; 95% CI, 1.70–7.07), and initial shockable rhythm (RR, 2.25; 95% CI, 2.05–2.48).

Conclusions

Current evidence indicates that gasping can predict short and long outcomes in patients with OHCA.In addition, gasping is associated with a high likelihood of initial shockable rhythm,which may contribute to positive outcomes.

Clinical and Autopsy Characteristics of Fatal Methamphetamine Toxicity in Australia

Characteristics of death attributed solely to methamphetamine toxicity (MT, n = 93) by forensic pathologists were examined and compared to cases of multiple drug toxicity (MDT, n = 634). The mean age of MT cases was 36.7 years, and 86.0% were male. Strenuous activity was reported in 12.9%. The most common witness observations were: collapse (60.3%), difficulty in breathing (36.2%), and hyperthermia (27.6%). MT cases had higher blood methamphetamine (0.54 vs. 0.11 mg/L) and amphetamine (0.04 vs. 0.02 mg/L) concentrations and lower likelihoods for opioids (12.5% vs. 80.9%), hypnosedatives (27.3 vs. 60.7%), antidepressants (14.8 vs. 29.8%), and antipsychotics (9.1 vs. 19.7%). MT cases had significantly heavier hearts than MDT cases (423.4 vs. 385.8 g) and were more likely to have cardiomegaly (37.1 vs. 20.4%) and replacement fibrosis (25.7 vs. 14.5%). The clinical picture was of a sudden cardiac event in a middle-aged man with a high methamphetamine concentration. Cardiovascular signs of heavy methamphetamine use are frequently seen.

'She's sort of breathing': What linguistic factors determine call-taker recognition of agonal breathing in emergency calls for cardiac arrest?

BACKGROUND

In emergency ambulance calls, agonal breathing remains a barrier to the recognition of out-of-hospital cardiac arrest (OHCA), initiation of cardiopulmonary resuscitation, and rapid dispatch. We aimed to explore whether the language used by callers to describe breathing had an impact on call-taker recognition of agonal breathing and hence cardiac arrest.

METHODS

We analysed 176 calls of paramedic-confirmed OHCA, stratified by recognition of OHCA (89 cases recognised, 87 cases not recognised). We investigated the linguistic features of callers' response to the question "is s/he breathing?" and examined the impact on subsequent coding by call-takers.

RESULTS

Among all cases (recognised and non-recognised), 64% (113/176) of callers said that the patients were breathing (yes-answers). We identified two categories of yes-answers: 56% (63/113) were plain answers, confirming that the patient was breathing ("he's breathing"); and 44% (50/113) were qualified answers, containing additional information ("yes but gasping"). Qualified yes-answers were suggestive of agonal breathing. Yet these answers were often not pursued and most (32/50) of these calls were not recognised as OHCA at dispatch.

CONCLUSION

There is potential for improved recognition of agonal breathing if call-takers are trained to be alert to any qualification following a confirmation that the patient is breathing.

Long-Term Prognostic Value of Gasping During Out-of-Hospital Cardiac Arrest

BACKGROUND

Gasping is a natural reflex that enhances oxygenation and circulation during cardiopulmonary resuscitation (CPR).

OBJECTIVES

This study sought to assess the relationship between gasping during out-of-hospital cardiac arrest and 1-year survival with favorable neurological outcomes.

METHODS

The authors prospectively collected incidence of gasping on all evaluable subjects in a multicenter, randomized, controlled, National Institutes of Health-funded out-of-hospital cardiac arrest clinical trial from August 2007 to July 2009. The association between gasping and 1-year survival with favorable neurological function, defined as a Cerebral Performance Category (CPC) score ≤2 was estimated using multivariable logistic regression.

RESULTS

The rates of 1-year survival with a CPC score of ≤2 were 5.4% (98 of 1,827) overall, and 20% (36 of 177) and 3.7% (61 of 1,643) for individuals with and without spontaneous gasping or agonal respiration during CPR, respectively. In multivariable analysis, 1-year survival with CPC ≤2 was independently associated with younger age (odds ratio [OR] for 1 SD increment 0.57; 95% confidence interval [CI]: 0.43 to 0.76), gasping during CPR (OR: 3.94; 95% CI: 2.09 to 7.44), shockable initial recorded rhythm (OR: 16.50; 95% CI: 7.40 to 36.81), shorter CPR duration (OR: 0.31; 95% CI: 0.19 to 0.51), lower epinephrine dosage (OR: 0.47; 95% CI: 0.25 to 0.87), and pulmonary edema (OR: 3.41; 95% CI: 1.53 to 7.60). Gasping combined with a shockable initial recorded rhythm had a 57-fold higher OR (95% CI: 23.49 to 136.92) of 1-year survival with CPC ≤2 versus no gasping and no shockable rhythm.

CONCLUSIONS

Gasping during CPR was independently associated with increased 1-year survival with CPC ≤2, regardless of the first recorded rhythm. These findings underscore the importance of not terminating resuscitation prematurely in gasping patients and the need to routinely recognize, monitor, and record data on gasping in all future cardiac arrest trials and registries.

Circulatory Failure During Noninhaled Forms of Cyanide Intoxication

Our objective was to determine how circulatory failure develops following systemic administration of potassium cyanide (KCN). We used a noninhaled modality of intoxication, wherein the change in breathing pattern would not influence the diffusion of CN into the blood, akin to the effects of ingesting toxic levels of CN. In a group of 300 to 400 g rats, CN-induced coma (CN i.p., 7 mg/kg) produced a central apnea within 2 to 3 min along with a potent and prolonged gasping pattern leading to autoresuscitation in 38% of the animals. Motor deficits and neuronal necrosis were nevertheless observed in the surviving animals. To clarify the mechanisms leading to potential autoresuscitation versus asystole, 12 urethane-anesthetized rats were then exposed to the lowest possible levels of CN exposure that would lead to breathing depression within 7 to 8 min; this dose averaged 0.375 mg/kg/min i.v. At this level of intoxication, a cardiac depression developed several minutes only after the onset of the apnea, leading to cardiac asystole as PaO2 reached value approximately 15 Torr, unless breathing was maintained by mechanical ventilation or through spontaneous gasping. Higher levels of KCN exposure in 10 animals provoked a primary cardiac depression, which led to a rapid cardiac arrest by pulseless electrical activity (PEA) despite the maintenance of PaO2 by mechanical ventilation. These effects were totally unrelated to the potassium contained in KCN. It is concluded that circulatory failure can develop as a direct consequence of CN-induced apnea but in a narrow range of exposure. In this "low" range, maintaining pulmonary gas exchange after exposure, through mechanical ventilation (or spontaneous gasping), can reverse cardiac depression and restore spontaneous breathing. At higher level of intoxication, cardiac depression is to be treated as a specific and spontaneously irreversible consequence of CN exposure, leading to a PEA.

Sudden unexpected death in epilepsy: basic mechanisms and clinical implications for prevention

Sudden unexpected death in epilepsy (SUDEP) is the most common cause of death in patients with intractable epilepsy. The substantial lifetime risk of SUDEP and the lack of a clear pathophysiological connection between epilepsy itself and sudden death have fuelled increased attention to this phenomenon. Understanding the mechanisms underlying SUDEP is paramount to developing preventative strategies. In this review, we discuss SUDEP population studies, case-control studies, witnessed and monitored cases, as well as human seizure cardiorespiratory findings related to SUDEP, and SUDEP animal models. We integrate these data to suggest the most probable mechanisms underlying SUDEP. Understanding the modifiable risk factors and pathophysiology allows us to discuss potential preventative strategies.

Is It Possible to Maintain Consciousness and Spontaneous Ventilation with Chest Compression in the Early Phase of Cardiac Arrest?

Chest compression is important in cardiopulmonary resuscitation. However, life support algorithms do not specify when chest compression should be initiated in patients with persistent spontaneous normal breathing in the early phase after cardiac arrest. Here we describe the case of a 69-year-old man who underwent femoral bypass surgery and was extubated at the end of the procedure. After extubation, the patient's breathing pattern and respiratory rate were normal. The patient subsequently developed ventricular fibrillation, evident on two monitors. Because defibrillation was ineffective, chest compression was initiated even though the patient had spontaneous normal breathing and defensive motor reflexes, which were continued throughout resuscitation. He regained consciousness and underwent tracheal extubation without neurological sequelae on postoperative day 1. This case highlights the necessity of chest compression in the early phase of cardiac arrest.

From unwitnessed fatality to witnessed rescue: Pharmacologic intervention in sudden unexpected death in epilepsy

The mechanisms of sudden unexpected death in epilepsy (SUDEP) have been difficult to define, as most cases occur unwitnessed, and physiologic recordings have been obtained in only a handful of cases. However, recent data obtained from human cases and experimental studies in animal models have brought us closer to identifying potential mechanisms. Theories of SUDEP should be able to explain how a seizure starting in the forebrain can sometimes lead to changes in brainstem cardiorespiratory control mechanisms. Herein we focus on three major themes of work on the causes of SUDEP. First, evidence is reviewed identifying postictal hypoventilation as a major contributor to the cause of death. Second, data are discussed that brainstem serotonin and adenosine pathways may be involved, as well as how they may contribute. Finally, parallels are drawn between SIDS and SUDEP, and we highlight similarities pointing to the possibility of shared pathophysiology involving combined failure of respiratory and cardiovascular control mechanisms. Knowledge about the causes of SUDEP may lead to potential pharmacologic approaches for prevention. We end by describing how translation of this work may result in future applications to clinical care.

Periodic breathing with no heart beat

A protocol was originally designed to study breathing control during and following cardiac arrest in humans, taking advantage of the period of pulseless ventricular fibrillation (PVF) produced while testing a newly implanted cardioverter-defibrillator device. A patient aged in his 60s with New York Heart Association class III heart failure (HF) (left ventricular ejection fraction of 25%) who was originally part of this study displayed permanent periodic breathing (PB) and was then excluded from the final data analysis; his response is presented in this report. The 8- to 9-s PVF was incidentally produced during the ascending phase of a PB cycle, followed by another 12-s recovery period of low BP. PVF and its recovery had no effect on PB characteristics (period or amplitude). This occurred despite a profound change in Paco2, cerebral blood flow, and perfusion of the carotid bodies. It is concluded that PB in patients with HF could be produced by primary oscillations originating from the central pattern generator.

Sudden cardiac arrest and death following application of shocks from a TASER electronic control device

BACKGROUND

The safety of electronic control devices (ECDs) has been questioned. The goal of this study was to analyze in detail cases of loss of consciousness associated with ECD deployment.

METHODS AND RESULTS

Eight cases of TASER X26 ECD-induced loss of consciousness were studied. In each instance, when available, police, medical, and emergency response records, ECD dataport interrogation, automated external defibrillator information, ECG strips, depositions, and autopsy results were analyzed. First recorded rhythms were ventricular tachycardia/fibrillation in 6 cases and asystole (after ≈ 30 minutes of nonresponsiveness) in 1 case. An external defibrillator reported a shockable rhythm in 1 case, but no recording was made. This report offers evidence detailing the mechanism by which an ECD can produce transthoracic stimulation resulting in cardiac electrical capture and ventricular arrhythmias leading to cardiac arrest.

CONCLUSIONS

ECD stimulation can cause cardiac electrical capture and provoke cardiac arrest resulting from ventricular tachycardia/ventricular fibrillation. After prolonged ventricular tachycardia/ventricular fibrillation without resuscitation, asystole develops.

Breathing during cardiac arrest following exercise: a new function of the respiratory system?

We have found in four sheep that, following a muscular exercise, minute ventilation is maintained for 34-131 s during a cardiac arrest (CA), at a magnitude (from 28.2 and 54.7 l min(-1)) similar to the level of ventilation (and thus proportional to the metabolic rate) preceding the period of asystole. Breathing was maintained despite the lack of pulmonary blood flow and the cessation of the muscle contractions, leading to a dramatic reduction in alveolar FCO(2) (1.9 ± 1%). Secondly, swings in arterial blood pressure (ABP) were observed (pulse pressure of 31 ± 3 Torr) in phase with breathing movements in place of the cardiac activity. This "protective" response, deprived from any role in blood gas homeostasis, as circulation is virtually abolished, is not predictable from the traditional respiratory control feedback systems thought to be involved in exercise. We are presenting the view that this response, dissociated from the pulmonary gas exchanges, is the expression of a rudimentary defense mechanism aimed at limiting the consequences of an acute failure of the cardiac pump by the thoraco-abdominal pump.