The first quantitative report of ventilation rate during in-hospital resuscitation of older children and adolescents

Aim

During adult cardiac arrest, rescuers frequently provide ventilations at rates exceeding those recommended by the American Heart Association (AHA). Excessive ventilation is associated with worse clinical outcome after adult cardiac arrest. This study is the first to characterize ventilation rate adherence to AHA guidelines during in-hospital pediatric cardiac arrest resuscitation.

Patients and methods

We prospectively enrolled children and adolescents (≥8 years of age) who suffered a cardiac arrest in a pediatric intensive care unit (PICU) or emergency department (ED) of a tertiary-care pediatric hospital. Ventilation rate (breaths per minute [bpm]) was monitored via changes in chest wall impedance (CWI) recorded by defibrillator electrode pads during cardiopulmonary resuscitation (CPR).

Results

Twenty-four CPR events were enrolled yielding 588 thirty-second CPR epochs. The proportion of CPR epochs with ventilation rates exceeding AHA guidelines (>10 bpm) was 63% (CI⁹⁵ 59-67%), significantly higher than our a priori hypothesis of 30% (p < 0.01). The proportion of CPR epochs with ventilation rates exceeding 20 bpm was 20% (CI⁹⁵ 17-23). After controlling for location of arrest and initial event rhythm, resuscitations that occurred on nights/weekends were 3.6 times (CI⁹⁵: 1.6-7.9, p < 0.01) more likely to have a ventilation rate exceeding AHA guidelines.

Conclusions

During in-hospital pediatric cardiac arrest, rescuers frequently provide artificial ventilations at rates in excess of AHA guidelines, with twenty percent of CPR time having ventilation rates double that recommended. Excessive ventilation was particularly common during CPR events that occurred on nights/weekends.     

CPR quality improvement during in-hospital cardiac arrest using a real-time audiovisual feedback system

BACKGROUND: Cardiopulmonary resuscitation (CPR) quality during actual cardiac arrest has been found to be deficient in several recent investigations. We hypothesized that real-time feedback during CPR would improve the performance of chest compressions and ventilations during in-hospital cardiac arrest. METHODS: An investigational monitor/defibrillator with CPR-sensing and feedback capabilities was used during in-hospital cardiac arrests from December 2004 to December 2005. Chest compression and ventilation characteristics were recorded and quantified for the first 5 min of resuscitation and compared to a baseline cohort of arrest episodes without feedback, from December 2002 to April 2004. RESULTS: Data from 55 resuscitation episodes in the baseline pre-intervention group were compared to 101 resuscitations in the feedback intervention group. There was a trend toward improvement in the mean values of CPR variables in the feedback group with a statistically significant narrowing of CPR variable distributions including chest compression rate (104+/-18 to 100+/-13 min(-1); test of means, p=0.16; test of variance, p=0.003) and ventilation rate (20+/-10 to 18+/-8 min(-1); test of means, p=0.12; test of variance, p=0.04). There were no statistically significant differences between the groups in either return of spontaneous circulation or survival to hospital discharge. CONCLUSIONS: Real-time CPR-sensing and feedback technology modestly improved the quality of CPR during in-hospital cardiac arrest, and may serve as a useful adjunct for rescuers during resuscitation efforts. However, feedback specifics should be optimized for maximal benefit and additional studies will be required to assess whether gains in CPR quality translate to improvements in survival.     

主动按压减压结合高频通气对心肺复苏犬的循环效应影响

目的　比较标准心肺复苏、主动按压减压心肺复苏、主动按压减压结合高频通气心肺复苏三种复苏法对心肺复苏循环效应影响 ;评价主动按压减压结合高频通气用于心肺复苏的可行性。方法　将9条犬经电击致颤制成心搏骤停模型 ,每只犬先后实施三种复苏法 ,①标准心肺复苏 ;②主动按压减压心肺复苏 ;③主动按压减压结合高频通气心肺复苏 ,实验顺序由随机法确定 ,每种复苏方法进行 5min ,待循环动力学稳定后记录收缩压、舒张压、心输出量。结果　收缩压、舒张压、心输出量均为主动按压减压结合高频通气模式大于主动按压减压心肺复苏模式 (P <0 0 1) ;主动按压减压心肺复苏模式大于标准心肺复苏模式 (P <0 0 1)。标准心肺复苏模式和主动按压减压心肺复苏模式胸外按压停顿期血压降至零 ,而主动按压减压结合高频通气心肺复苏模式血压持续稳定。结论　主动按压减压心肺复苏优于标准心肺复苏模式。主动按压减压结合高频通气心肺复苏模式既可产生较高的动脉血压、心输出量 ,又可提供充分的气体交换 ,值得进一步研究和推广应用     

Quality of cardiopulmonary resuscitation before and during transport in out-of-hospital cardiac arrest

AIM OF THE STUDY: To evaluate quality of cardiopulmonary resuscitation (CPR) performed during transport after out-of-hospital cardiac arrest. MATERIALS AND METHODS: Retrospective, observational study of all non-traumatic cardiac arrest patients older than 18 years who received CPR both before and during transport between May 2003 and December 2006 from the community run EMS system in Oslo. Chest compressions and ventilations were detected from impedance changes in routinely collected ECG signals, and hands-off ratio calculated as time without chest compressions divided by total CPR time. RESULTS: Seventy-five of 787 consecutive out-of-hospital cardiac arrest patients met the inclusion criteria. Quality data were available from 36 of 66 patients receiving manual CPR and 7 of 9 receiving mechanical CPR. CPR was performed for mean 21+/-11 min before and 12+/-8 min during transport. With manual CPR hands-off ratio increased from 0.19+/-0.09 on-scene to 0.27+/-0.15 (p=0.002) during transport. Compression and ventilation rates were unchanged causing a reduction in compressions per minute from 94+/-14 min(-1) to 82+/-19 min(-1) (p=0.001). Quality was significantly better with mechanical than manual CPR. Four patients (5%) survived to hospital discharge; two with manual CPR (Cerebral performance categories (CPC) 1 and 2), and two with mechanical CPR (CPC scores 3 and 4). No discharged patients had any spontaneous circulation during transport. CONCLUSIONS: The fraction of time without chest compressions increased during transport of out-of-hospital cardiac arrest patients. Every effort should therefore be made to stabilise patients on-scene before transport to hospital, but all transport with ongoing CPR is not futile.     

Advanced cardiac life support before and after tracheal intubation--direct measurements of quality

STUDY HYPOTHESIS: Tracheal intubation should improve the quality of cardiopulmonary resuscitation (CPR) by enabling adequate ventilation without pauses in external chest compressions. METHODS: Out-of-hospital cardiac arrests of all causes were sampled in this non-randomized, observational study of advanced cardiac life support in three ambulance services (Akershus, London and Stockholm). Prototype defibrillators (Heartstart 4000SP, Philips Medical Systems, Andover, MA, USA and Laerdal Medical AS, Stavanger, Norway) registered all chest compressions via an extra chest pad with an accelerometer mounted over the lower part of sternum and ventilations from changes in transthoracic impedance between the standard defibrillator pads. The quality of CPR was analyzed off-line for 119 episodes. Numbers and differences are given as mean +/- S.D. and differences as mean and 95% confidence intervals. RESULTS: Chest compressions were not given in cardiac arrest for 61 +/- 20% of the time before intubation compared to 41 +/- 18% after intubation (difference: 20% (16-24%)). Compressions and ventilations per minute increased from 47 +/- 25 to 71 +/- 23 (difference: 24 (19, 29)) and 5.6 +/- 3.7 to 14 +/- 5.0 (difference: 8.7 (7.6, 9.8)) respectively. Four cases of unrecognized oesophageal intubation (3%) were suspected from the disappearance of ventilation induced changes in thoracic impedance after intubation. CONCLUSION: The quality of CPR improved after tracheal intubation, but the fraction of time without blood flow was still high and not according to international guidelines. On-line analysis of thoracic impedance might be a practicable aid to avoid unrecognized oesophageal intubation, but this area needs further research.     

Hands-on time during cardiopulmonary resuscitation is affected by the process of teambuilding: a prospective randomised simulator-based trial

Background

Cardiac arrests are handled by teams rather than by individual health-care workers. Recent investigations demonstrate that adherence to CPR guidelines can be less than optimal, that deviations from treatment algorithms are associated with lower survival rates, and that deficits in performance are associated with shortcomings in the process of team-building. The aim of this study was to explore and quantify the effects of ad-hoc team-building on the adherence to the algorithms of CPR among two types of physicians that play an important role as first responders during CPR: general practitioners and hospital physicians.

Methods

To unmask team-building this prospective randomised study compared the performance of preformed teams, i.e. teams that had undergone their process of team-building prior to the onset of a cardiac arrest, with that of teams that had to form ad-hoc during the cardiac arrest. 50 teams consisting of three general practitioners each and 50 teams consisting of three hospital physicians each, were randomised to two different versions of a simulated witnessed cardiac arrest: the arrest occurred either in the presence of only one physician while the remaining two physicians were summoned to help ("ad-hoc"), or it occurred in the presence of all three physicians ("preformed"). All scenarios were videotaped and performance was analysed post-hoc by two independent observers.

Results

Compared to preformed teams, ad-hoc forming teams had less hands-on time during the first 180 seconds of the arrest (93 ± 37 vs. 124 ± 33 sec, P < 0.0001), delayed their first defibrillation (67 ± 42 vs. 107 ± 46 sec, P < 0.0001), and made less leadership statements (15 ± 5 vs. 21 ± 6, P < 0.0001).

Conclusion

Hands-on time and time to defibrillation, two performance markers of CPR with a proven relevance for medical outcome, are negatively affected by shortcomings in the process of ad-hoc team-building and particularly deficits in leadership. Team-building has thus to be regarded as an additional task imposed on teams forming ad-hoc during CPR. All physicians should be aware that early structuring of the own team is a prerequisite for timely and effective execution of CPR.     

The effects of an automatic,low pressure and constant flow ventilation device versus manual ventilation during cardiovascular resuscitation in a porcine model of cardiac arrest

Background

Cardiac arrest is an important cause of mortality. Cardiopulmonary resuscitation (CPR) improves survival, however, delivery of effective CPR can be challenging and combining effective chest compressions with ventilation, while avoiding over-ventilation is difficult. We hypothesized that ventilation with a pneumatically powered, automatic ventilator (Oxylator^®) can provide adequate ventilation in a model of cardiac arrest and improve the consistency of ventilations during CPR.

Methods/results

Twelve pigs (∼40 kg, either sex) underwent 3 episodes each of cardiac arrest and resuscitation consisting of 30 s of untreated ventricular fibrillation, followed by 5 min of CPR, defibrillation, and ∼30 min of recovery. During CPR in each episode, pigs were ventilated in 1 of 3 ways in random balanced order: manual ventilation using AMBU bag (12 breaths/min), low pressure Oxylator^® (maximum airway pressure 15 cmH₂O with 20 L/min constant flow in automatic mode [Ox15/20]), or high pressure Oxylator^® (maximum airway pressure 20 cmH₂O with 30 L/min constant flow in automatic mode [Ox20/30]). During CPR, both Ox15/20 and Ox20/30 resulted in higher levels of positive end expiratory pressure than manual ventilation. Ox15/20 ventilation also resulted in higher arterial pCO₂ than manual ventilation. Ox20/30 ventilation yielded higher arterial pO₂ and a lower arterial–alveolar gradient than manual ventilation. All pigs were successfully defibrillated, and no measured haemodynamic variables were different between the groups.

Conclusion

Ventilation with an automatic ventilation device during CPR is feasible and provides adequate ventilation and comparable haemodynamics when compared to manual bag ventilation.     

Characteristics and outcome among patients suffering from in hospital cardiac arrest in relation to whether the arrest took place during office hours

AIM: To describe the characteristics and outcome among patients suffering from in hospital cardiac arrest in relation to whether the arrest took place during office hours. PATIENTS: All patients suffering in hospital cardiac arrest in Sahlgrenska University hospital in G?teborg, Sweden between 1994 and 1999 in whom resuscitative efforts were attempted and for whom the time when the cardiopulmonary resuscitation (CPR) team was alerted. METHODS: Prospective recording of various factors at resuscitation including the time when the CPR team was alerted. Retrospective evaluation via medical records of patients previous history and final outcome. RESULTS: Among patients in whom the arrest took place during office hours (08:00-16:30 h) the overall survival rate was 49% as compared with 26% among the remaining patients (P<0.0001). The corresponding figures for patients found in ventricular fibrillation were 66 and 44% (P=0.0001), for patients found in asystole 33 and 22% (NS) and for patients found in pulseless electrical activity 14 and 3% (NS). When correcting for dissimilarities in previous history and factors at resuscitation the adjusted odds ratio for patients to be discharged alive who had the arrest during office hours was 2.07 (1.40-3.06) as compared with patients who had an arrest outside office hours. CONCLUSION: Among patients suffering from in hospital cardiac arrest and in whom CPR was attempted those who had the arrest during office hours had a survival rate being more than twice that of patients who had the arrest during other times of the day and night. These results indicate that the preparedness for optimal treatment of in hospital cardiac arrest is of ultimate importance for the final outcome and that an increased preparedness during evenings and nights might increase survival among patients suffering from in hospital cardiac arrest.     

Evaluation of telephone CPR advice for adult cardiac arrest patients

INTRODUCTION: Telephone cardiopulmonary resuscitation (CPR) advice aims to increase the quality and quantity of bystander CPR, one of the few interventions shown to improve outcome in cardiac arrest. We evaluated a current telephone protocol (based on 2000 ILCOR guidelines) to assess the effectiveness of verbal CPR instructions. METHODS: Emergency calls were identified from AMPDS codes for cardiac arrest and checked against the ambulance patient record form to confirm the diagnosis. Calls over a seven month period were analysed retrospectively, and the time taken to perform interventions calculated. RESULTS: 176 calls were analysed; of those 145 (82.4%) were confirmed cases of cardiac arrest. CPR was already underway in 11 cases (7.5%), 101 callers (69.7%) agreed to attempt CPR with telephone instructions. The median time to open the airway was 128s (62-482s), to perform the first ventilation was 247s (80-633s), and to perform the first chest compression was 315s (153-750s). Of those attempting CPR, 21 (20.8%) stopped because they were unable to move the patient onto a hard surface, and 28 (27.7%) required multiple attempts to perform effective ventilations. In the telephone CPR group 42/101 (40.6%) did not receive any chest compressions before the arrival of the ambulance crew. CONCLUSIONS: Although current telephone-CPR instructions significantly improve the numbers of patients in whom bystander CPR is attempted, significant delays and poor quality CPR are likely to limit any benefits.     

Organisation of in-hospital cardiac arrest teams – A nationwide study

BackgroundIn-hospital cardiac arrests are treated by a team of health care providers. Improving team performance may increase survival. Currently, no international standards for cardiac arrest teams exist in terms of member composition and allocation of tasks.AimTo describe the composition of in-hospital cardiac arrest teams and review pre-arrest allocation of tasks.MethodsA nationwide cross-sectional study was performed. Data on cardiac arrest teams and pre-arrest allocation of tasks were collected from protocols on resuscitation required for hospital accreditation in Denmark. Additional data were collected through telephone interviews and email correspondence. Psychiatric hospitals and hospitals serving outpatients only were excluded.ResultsData on the cardiac arrest team were available from 44 of 47 hospitals. The median team size was 5 (25th percentile; 75th percentile: 4; 6) members. Teams included a nurse anaesthetist (100%), a medical house officer (82%), an orderly (73%), an anaesthesiology house officer (64%) and a medical assistant (20%). Less likely to participate was a cardiology house officer (23%) or a cardiology specialist registrar (5%). Overall, a specialist registrar was represented on 20% of teams and 20% of cardiac arrest teams had a different team composition during nights and weekends. In total, 41% of teams did not define a team leader pre-arrest, and the majority of the teams did not define the tasks of the remaining team members.ConclusionIn Denmark, there are major differences among cardiac arrest teams. This includes team size, profession of team members, medical specialty and seniority of the physicians. Nearly half of the hospitals do not define a cardiac arrest team leader and the majority do not define the tasks of the remaining team members.     

Cardiopulmonary resuscitation: a mandatory training program for nursing staff

At Flinders Medical Centre, a 600 bed teaching hospital in Adelaide, South Australia, there are between eighty and one hundred cardiac arrests in the general wards areas each year. From the time an arrest occurs until the arrest team arrives, the patient's life will depend on the speed with which Cardiopulmonary Resuscitation (CPR) is initiated and the effectiveness of the CPR performed by ward staff. The outcome of cardiac arrest patients who receive promptly administered CPR is extensively documented in literature on the subject. When an arrest occurs in the ward at Flinders, staff activate an emergency call to the "cardiac arrest team", which consists of three medical staff members and one nursing staff member. The nurse, from the Intensive Care Unit, is responsible for coordinating the actions of the nursing staff during the arrest. Following the arrest an audit sheet is completed with details of the patient, the arrest, treatment, and any other pertinent information. Until 1985 it was not unusual at Flinders for arrest audit sheets to have comments such as: "CPR not performed by ward staff" or "CPR not being performed correctly by ward staff" or, even worse, "Ward staff disappeared when the arrest team arrived". In many hospitals throughout Australia this was, and may still be, a familiar problem. The nursing department at Flinders believed that if a program could be established in which nurses were given the opportunity to learn and practise CPR, they could gain the skills necessary to perform basic CPR in the ward until the arrest team arrived. In 1985 a coordinator of such a program was appointed, and it became mandatory at Flinders for all nursing staff to learn and be accredited annually in basic CPR skills. This article describes how the CPR Program started, its progress, and its results.     

Residents feel unprepared and unsupervised as leaders of cardiac arrest teams in teaching hospitals: a survey of internal medicine residents

OBJECTIVE: We aimed to determine internal medicine residents' perceptions of the adequacy of their training to serve as in-hospital cardiac arrest team leaders, given the responsibility of managing acutely critically ill patients and with recent evidence suggesting that the quality of cardiopulmonary resuscitation provided in teaching hospitals is suboptimal. DESIGN: Cross-sectional postal survey. SETTING: Canadian internal medicine training programs. PARTICIPANTS: Internal medicine residents attending Canadian English-speaking medical schools. INTERVENTIONS: A survey was mailed to internal medicine residents asking questions relating to four domains: adequacy of training, perception of preparedness, adequacy of supervision and feedback, and effectiveness of additional training tools. MEASUREMENTS AND MAIN RESULTS: Of the 654 residents who were sent the survey, 289 residents (44.2%) responded. Almost half of the respondents (49.3%) felt inadequately trained to lead cardiac arrest teams. Many (50.9%) felt that the advanced cardiac life support course did not provide the necessary training for team leadership. A substantial number of respondents (40%) reported receiving no additional cardiac arrest training beyond the advanced cardiac life support course. Only 52.1% of respondents felt prepared to lead a cardiac arrest team, with 55.3% worrying that they made errors. Few respondents reported receiving supervision during weekdays (14.2%) or evenings and weekends (1.4%). Very few respondents reported receiving postevent debriefing (5.9%) or any performance feedback (1.3%). Level of training and receiving performance feedback were associated with perception of adequacy of training (r(2) = .085, p < .001). Respondents felt that additional training involving full-scale simulation, leadership skills training, and postevent debriefing would be most effective in increasing their skills and confidence. CONCLUSIONS: The results suggest that residents perceive deficits in their training and supervision to care for critically ill patients as cardiac arrest team leaders. This raises sufficient concern to prompt teaching hospitals and medical schools to consider including more appropriate supervision, feedback, and further education for residents in their role as cardiac arrest team leaders.     

Efficacy of bystander CPR: intervention by lay people and by health care professionals

BACKGROUND: Early cardiopulmonary resuscitation (CPR) by bystanders prior to the arrival of the rescue team has been shown to be associated with increased survival after out-of-hospital cardiac arrest. The aim of this survey was to evaluate the impact on survival of no bystander CPR, lay bystander CPR and professional bystander CPR. METHODS: Patients suffering an out-of-hospital cardiac arrest in Sweden between 1990 and 2002 who were given CPR and were not witnessed by the ambulance crew were included. RESULTS: In all, 29,711 patients were included, 36% of whom received bystander CPR prior to the arrival of the rescue team. Among the latter, 72% received CPR from lay people and 28% from professionals. Survival to 1 month was 2.2% among those who received no bystander CPR, 4.9% among those who received bystander CPR from lay people (p<0.0001) and 9.2% among those who received bystander CPR from professionals (p<0.0001 compared with bystander CPR by lay people). In a multivariate analysis, lay bystander CPR was associated with improved survival compared to no bystander CPR (OR: 2.04; 95% CI: 1.72-2.42), and professional bystander CPR was associated with improved survival compared to lay bystander CPR (OR: 1.37; 95% CI: 1.12-1.67). CONCLUSION: Among patients suffering an out-of-hospital cardiac arrest, bystander CPR by lay persons (excluding health care professionals) is associated with an increased chance of survival. Furthermore, there is a distinction between lay persons and health care providers; survival is higher when the latter perform bystander CPR. However, these results may not be explained by differences in the quality of CPR.     

Feasibility of automated rhythm assessment in chest compression pauses during cardiopulmonary resuscitation

Aim

To demonstrate the feasibility of doing a reliable rhythm analysis in the chest compression pauses (e.g. pauses for two ventilations) during cardiopulmonary resuscitation (CPR).

Methods

We extracted 110 shockable and 466 nonshockable segments from 235 out-of-hospital cardiac arrest episodes. Pauses in chest compressions were already annotated in the episodes. We classified pauses as ventilation or non-ventilation pause using the transthoracic impedance. A high-temporal resolution shock advice algorithm (SAA) that gives a shock/no-shock decision in 3 s was launched once for every pause longer than 3 s. The sensitivity and specificity of the SAA for the analyses during the pauses were computed.

Results

We identified 4476 pauses, 3263 were ventilation pauses and 2183 had two ventilations. The median of the mean duration per segment of all pauses and of pauses with two ventilations were 6.1 s (4.9–7.5 s) and 5.1 s (4.2–6.4 s), respectively. A total of 91.8% of the pauses and 95.3% of the pauses with two ventilations were long enough to launch the SAA. The overall sensitivity and specificity were 95.8% (90% low one-sided CI, 94.3%) and 96.8% (CI, 96.2%), respectively. There were no significant differences between the sensitivities (P = 0.84) and the specificities (P = 0.18) for the ventilation and the non-ventilation pauses.

Conclusion

Chest compression pauses are frequent and of sufficient duration to launch a high-temporal resolution SAA. During these pauses rhythm analysis was reliable. Pre-shock pauses could be minimised by analysing the rhythm during ventilation pauses when CPR is delivered at 30:2 compression:ventilation ratio.     

Reducing ventilation frequency during cardiopulmonary resuscitation in a porcine model of cardiac arrest

INTRODUCTION: American Heart Association/American College of Cardiology guidelines recommend a compression-to-ventilation ratio (C/V ratio) of 15:2 during cardiopulmonary resuscitation (CPR) for out-of-the-hospital cardiac arrest. Recent data have shown that frequent ventilations are unnecessary and may be harmful during CPR, since each positive-pressure ventilation increases intrathoracic pressure and may increase intracranial pressure and decrease venous blood return to the right heart and thereby decrease both the cerebral and coronary perfusion pressures. HYPOTHESIS: We hypothesized that reducing the ventilation rate by increasing the C/V ratio from 15:2 to 15:1 will increase vital-organ perfusion pressures without compromising oxygenation and acid-base balance. METHODS: Direct-current ventricular fibrillation was induced in 8 pigs. After 4 min of untreated ventricular fibrillation without ventilation, all animals received 4 min of standard CPR with a C/V ratio of 15:2. Animals were then randomized to either (A) a C/V ratio of 15:1 and then 15:2, or (B) a C/V ratio of 15:2 and then 15:1, for 3 min each. During CPR, ventilations were delivered with an automatic transport ventilator, with 100% oxygen. Right atrial pressure, intratracheal pressure (a surrogate for intrathoracic pressure), aortic pressure, and intracranial pressure were measured. Coronary perfusion pressure was calculated as diastolic aortic pressure minus right atrial pressure. Cerebral perfusion pressure was calculated as mean aortic pressure minus mean intracranial pressure. Arterial blood gas values were obtained at the end of each intervention. A paired t test was used for statistical analysis, and a p value < 0.05 was considered significant. RESULTS: The mean +/- SEM values over 1 min with either 15:2 or 15:1 C/V ratios were as follows: intratracheal pressure 0.93 +/- 0.3 mm Hg versus 0.3 +/- 0.28 mm Hg, p = 0.006; coronary perfusion pressure 10.1 +/- 4.5 mm Hg versus 19.3 +/- 3.2 mm Hg, p = 0.007; intracranial pressure 25.4 +/- 2.7 mm Hg versus 25.7 +/- 2.7 mm Hg, p = NS; mean arterial pressure 33.1 +/- 3.7 mm Hg versus 40.2 +/- 3.6 mm Hg, p = 0.007; cerebral perfusion pressure 7.7 +/- 6.2 mm Hg versus 14.5 +/- 5.5 mm Hg, p = 0.008. Minute area intratracheal pressure was 55 +/- 17 mm Hg . s versus 22.3 +/- 10 mm Hg . s, p < 0.001. End-tidal CO(2) with 15:2 versus 15:1 was 24 +/- 3.6 mm Hg versus 29 +/- 2.5 mm Hg, respectively, p = 0.001. Arterial blood gas values were not significantly changed with 15:2 versus 15:1 C/V ratios: pH 7.28 +/- 0.03 versus 7.3 +/- 0.03; P(aCO(2)) 37.7 +/- 2.9 mm Hg versus 37.6 +/- 3.5 mm Hg; and P(aO(2)) 274 +/- 36 mm Hg versus 303 +/- 51 mm Hg. CONCLUSIONS: In a porcine model of ventricular fibrillation cardiac arrest, reducing the ventilation frequency during CPR by increasing the C/V ratio from 15:2 to 15:1 resulted in improved vital-organ perfusion pressures, higher end-tidal CO(2) levels, and no change in arterial oxygen content or acid-base balance.     

A Simulation Trial of Traditional Dispatcher-Assisted CPR Versus Compressions—Only Dispatcher-Assisted CPR

Objectives. Growing evidence indicates that it may not be essential to deliver ventilations in the first few minutes of CPR. We compared time to delivery of first compression in traditional CPR with ventilations andcompressions to compression-only CPR performed by untrained laypersons assisted by a mock 911 dispatcher. Methods. This randomized-controlled simulation study included a convenience sample of English-speaking emergency department visitors during a 6-month period. Exclusion criteria were prior CPR training or physical incapacity. A cardiac arrest scenario was presented to subjects who were then provided with one of two sets of telephone CPR instructions by a mock 911 dispatcher. One group received traditional CPR instructions (TCPR) andthe second group received compression only CPR instructions (COCPR). Subjects performed CPR on a Laerdal Resusci-Anne CPR manikin andrecording strips were analyzed for frequency andquality measures. Pre-and post-test questionnaires assessed subject fatigue andtelephone instruction understanding. The primary outcome was the time interval from 911 call to initiation of chest compressions. Analysis included Student t-test, Chi-square, andWilcoxon Rank Sum. Results. Of 377 potential subjects, 54 consented to randomization. The data from 50 subjects were analyzed. Compared to group TCPR, group COCPR initiated chest compressions faster (72 vs 117 sec, p < 0.0001), completed four cycles of CPR faster (168 vs. 250 sec, p < 0.0001), andpaused for a smaller percentage of the resuscitation (13% vs. 36%, p < 0.0001). Only 9% of ventilation opportunities in the TCPR group yielded ventilations of the correct volume. There were no differences between groups in perceived understanding of CPR instruction or fatigue. Conclusions. We have identified the potential timesavings that may occur during compressions-only CPR. Bystander resuscitation may be more efficient when ventilations are excluded from the CPR sequence.     

Automated External Defibrillator Program Does Not Impair Cardiopulmonary Resuscitation Initiation in the Public Access Defibrillation Trial

Objectives: To evaluate whether automated external defibrillator (AED) training and AED availability affected the response of volunteer rescuers and performance of cardiopulmonary resuscitation (CPR) in presumed out‐of‐hospital cardiac arrest (OOH‐CA) during the multicenter Public Access Defibrillation Trial. Methods: The Public Access Defibrillation Trial recruited 1,260 facilities in 24 North American regional sites to participate in a trial addressing survival from OOH‐CA when AED training and availability were added to a volunteer‐based emergency response team. Volunteers at each facility were trained to perform either CPR alone (CPR) or CPR in conjunction with AED use (CPR+AED) according to randomized assignments. This study reports the frequency of response and initiation of CPR actions (chest compressions and/or ventilations) by volunteers in the CPR and CPR+AED study groups. Results: A total of 314 presumed OOH‐CA episodes occurred in CPR facilities, and 308 occurred in CPR+AED facilities. The volunteers were matched well for age, gender, and other features. Overall, ventilations (23.1% vs. 13.1%), chest compressions (24.4% vs. 12.1%), and both actions (19.8% vs. 10.5%; all p < 0.05) were more commonly performed in OOH‐CA cases in the CPR+AED group. However, when only OOH‐CA cases with volunteers responding were analyzed, the rates of CPR actions were similar. In the subgroup of CPR+AED cases with a responding volunteer, the AED was turned on for only 47% of cases. Volunteers initiated a CPR action more commonly when the AED was turned on (60.7% vs. 39.3%; p = 0.003). Conclusions: In the Public Access Defibrillation Trial, rates of CPR actions for presumed OOH‐CA victims were low but similar for CPR and CPR+AED responding volunteer rescuers. Factors associated with volunteer response, CPR action initiation, and AED activation warrant further investigation.     

Does compression-only cardiopulmonary resuscitation generate adequate passive ventilation during cardiac arrest?

INTRODUCTION: The need for rescue breaths in bystander CPR has been questioned after several studies have shown that omitting ventilation does not worsen outcome. Chest compression may produce passive tidal volumes large enough to provide adequate ventilation in animal studies, but no recent clinical studies have examined this phenomenon. We measured passive ventilation during optimal chest compression to determine whether compression-only CPR provides adequate gas exchange during cardiac arrest. METHODS: Adult cardiac arrest patients were treated according to European Resuscitation Council guidelines. Chest compressions were performed using a mechanical chest compression device (LUCAS) with active decompression disabled to mimic manual compression. Respiratory variables were measured during periods of compression-only CPR. RESULTS: Emergency Department data were collected during compression-only CPR from 17 patients (11 male) aged 47-82 years who had suffered an out-of-hospital cardiac arrest. Median tidal volume per compression was 41.5 ml (range 33.0-62.1 ml), being considerably less than measured deadspace in all patients. Maximum end-tidal CO2 was 0.93 kPa (range 0.0-4.6 kPa). Minute volume CO2 was 19.5 ml (range 15.9-33.8; normal range 150-180 ml). CONCLUSIONS: At an advanced stage of cardiac arrest, passive ventilation during compression-only CPR is limited in its ability to maintain adequate gas exchange, with gas transport mechanisms associated with high frequency ventilation perhaps generating a very limited gas exchange. The effectiveness of passive ventilation during the early stages of CPR, when chest and lung compliance is greater, remains to be investigated.     

Reliability and accuracy of the thoracic impedance signal for measuring cardiopulmonary resuscitation quality metrics

AimTo determine the accuracy and reliability of the thoracic impedance (TI) signal to assess cardiopulmonary resuscitation (CPR) quality metrics.MethodsA dataset of 63 out-of-hospital cardiac arrest episodes containing the compression depth (CD), capnography and TI signals was used. We developed a chest compression (CC) and ventilation detector based on the TI signal. TI shows fluctuations due to CCs and ventilations. A decision algorithm classified the local maxima as CCs or ventilations. Seven CPR quality metrics were computed: mean CC-rate, fraction of minutes with inadequate CC-rate, chest compression fraction, mean ventilation rate, fraction of minutes with hyperventilation, instantaneous CC-rate and instantaneous ventilation rate. The CD and capnography signals were accepted as the gold standard for CC and ventilation detection respectively. The accuracy of the detector was evaluated in terms of sensitivity and positive predictive value (PPV). Distributions for each metric computed from the TI and from the gold standard were calculated and tested for normality using one sample Kolmogorov–Smirnov test. For normal and not normal distributions, two sample t-test and Mann–Whitney U test respectively were applied to test for equal means and medians respectively. Bland–Altman plots were represented for each metric to analyze the level of agreement between values obtained from the TI and gold standard.ResultsThe CC/ventilation detector had a median sensitivity/PPV of 97.2%/97.7% for CCs and 92.2%/81.0% for ventilations respectively. Distributions for all the metrics showed equal means or medians, and agreements >95% between metrics and gold standard was achieved for most of the episodes in the test set, except for the instantaneous ventilation rate.ConclusionWith our data, the TI can be reliably used to measure all the CPR quality metrics proposed in this study, except for the instantaneous ventilation rate.