A reappraisal of mouth-to-mouth ventilation during bystander-initiated cardiopulmonary resuscitation. A statement for healthcare professionals from the Ventilation Working Group of the Basic Life Support and Pediatric Life Support Subcommittees, American Heart Association

The medical use of oxygen: a time for critical reappraisal

Oxygen treatment has been a cornerstone of acute medical care for numerous pathological states. Initially, this was supported by the assumed need to avoid hypoxaemia and tissue hypoxia. Most acute treatment algorithms, therefore, recommended the liberal use of a high fraction of inspired oxygen, often without first confirming the presence of a hypoxic insult. However, recent physiological research has underlined the vasoconstrictor effects of hyperoxia on normal vasculature and, consequently, the risk of significant blood flow reduction to the at-risk tissue. Positive effects may be claimed simply by relief of an assumed local tissue hypoxia, such as in acute cardiovascular disease, brain ischaemia due to, for example, stroke or shock or carbon monoxide intoxication. However, in most situations, a generalized hypoxia is not the problem and a risk of negative hyperoxaemia-induced local vasoconstriction effects may instead be the reality. In preclinical studies, many important positive anti-inflammatory effects of both normobaric and hyperbaric oxygen have been repeatedly shown, often as surrogate end-points such as increases in gluthatione levels, reduced lipid peroxidation and neutrophil activation thus modifying ischaemia-reperfusion injury and also causing anti-apoptotic effects. However, in parallel, toxic effects of oxygen are also well known, including induced mucosal inflammation, pneumonitis and retrolental fibroplasia. Examining the available 'strong' clinical evidence, such as usually claimed for randomized controlled trials, few positive studies stand up to scrutiny and a number of trials have shown no effect or even been terminated early due to worse outcomes in the oxygen treatment arm. Recently, this has led to less aggressive approaches, even to not providing any supplemental oxygen, in several acute care settings, such as resuscitation of asphyxiated newborns, during acute myocardial infarction or after stroke or cardiac arrest. The safety of more advanced attempts to deliver increased oxygen levels to hypoxic or ischaemic tissues, such as with hyperbaric oxygen therapy, is therefore also being questioned. Here, we provide an overview of the present knowledge of the physiological effects of oxygen in relation to its therapeutic potential for different medical conditions, as well as considering the potential for harm. We conclude that the medical use of oxygen needs to be further examined in search of solid evidence of benefit in many of the current clinical settings in which it is routinely used.

Push hard, push fast, if you're downtown: a citation review of urban-centrism in American and European basic life support guidelines

Bystander cardiopulmonary resuscitation (CPR) improves out-of-hospital cardiac arrest (OHCA) survival. In settings with prolonged ambulance response times, skilled bystanders may be even more crucial. In 2010, American Heart Association (AHA) and European Resuscitation Council (ERC) introduced compression-only CPR as an alternative to conventional bystander CPR under some circumstances. The purpose of this citation review and document analysis is to determine whether the evidentiary basis for 2010 AHA and ERC guidelines attends to settings with prolonged ambulance response times or no formal ambulance dispatch services. Primary and secondary citations referring to epidemiological research comparing adult OHCA survival based on the type of bystander CPR were included in the analysis. Details extracted from the citations included a study description and primary outcome measure, the geographic location in which the study occurred, EMS response times, the role of dispatchers, and main findings and summary statistics regarding rates of survival among patients receiving no CPR, conventional CPR or compression-only CPR. The inclusion criteria were met by 10 studies. 9 studies took place exclusively in urban settings. Ambulance dispatchers played an integral role in 7 studies. The cited studies suggest either no survival benefit or harm arising from compression-only CPR in settings with extended ambulance response times. The evidentiary basis for 2010 AHA and ERC bystander CPR guidelines does not attend to settings without rapid ambulance response times or dispatch services. Standardized bystander CPR guidelines may require adaptation or reconsideration in these settings.

Development and implementation of an opioid overdose prevention and response program in Toronto, Ontario

OBJECTIVES

We describe the development of the first community-based opioid overdose prevention and response program with naloxone distribution offered by a public health unit in Canada (Prevent Overdose in Toronto, POINT).

PARTICIPANTS

The target population is people who use opioids by any route, throughout the City of Toronto.

SETTING

The POINT program is operated by the needle exchange program at Toronto Public Health (The Works) and offered at over 40 partner agency sites throughout Toronto.

INTERVENTION

POINT is a comprehensive program of overdose prevention and response training, including naloxone dispensing. Clients are instructed by public health staff on overdose risk factors, recognizing signs and symptoms of overdose, calling 911, naloxone administration, stimulation and chest compressions, and post-overdose care. Training is offered to clients one-on-one or in small groups. Clients receive a naloxone kit including two 1 mL ampoules of naloxone hydrochloride (0.4 mg/mL) and are advised to return to The Works for a refill and debriefing if the naloxone kit is used.

OUTCOMES

In the first 8 months of the program, 209 clients were trained. Clients have reported 17 administrations of naloxone, and all overdose victims have reportedly survived. Client demand for POINT training has been high, and Toronto Public Health has expanded its capacity to provide training. Overall, reception to the program has been overwhelmingly positive.

CONCLUSION

We are encouraged by the initial development and implementation experience with the naloxone program and its potential to save lives in Toronto. We have planned short-, intermediate-, and long-term process and outcome evaluations.

Effect of Severe Acute Respiratory Syndrome on Bystander Willingness to Perform Cardiopulmonary Resuscitation (CPR)–Is Compression–Only Preferred to Standard CPR?

Objective:

The effect of the severe acute respiratory syndrome (SARS) outbreak on the willingness of laypersons to provide bystander cardiopulmonary resuscitation (CPR) using standard CPR (SCPR) or compression-only CPR (CCPR) was evaluated.The preferred type of SCPR in the post-SARS era was assessed.

Methods:

A descriptive study was conducted through telephone interviews. Persons who attended a CPR coursefrom January 2000 through February 2003 answered a structured questionnaire. The respondents' willingnessto perform SCPR or CCPR during a witnessed cardiac arrest of an average adult stranger or that of a family member in the pre-SARS and the post-SARS era was surveyed.

Results:

Data for 305 respondents were processed. For the scenario of cardiac arrest of an average stranger, more respondents would perform CCPR than SCPR in the pre-SARS era (83.6% vs. 61.3%, p <0.001) and in the post- SARS era (77.4% vs. 28.9%, p <0.001). In the scenario of the cardiac arrest of a family member, more would perform CCPR than SCPR in the pre-SARS era (92.8% vs. 87.2%, p <0.001) and in the post-SARS era (92.8% vs. 84.9%, p <0.001). After SARS, more respondents were unwilling to perform SCPR (p <0.001) and CCPR (p <0.001) on strangers. After SARS, more respondents were unwilling to perform SCPR on a family member (p = 0.039), but there was no difference in the preference to perform CCPR (p = 1.000).

Conclusions:

Concerns about SARS adversely affected the willingness of respondents to perform SCPR or CCPRon strangers and to perform SCPR on family members.Compression-only CPR was preferred to SCPR to resuscitate strangers experiencing cardiac arrest after the emergence of SARS.

Pneumothorax During CPR Training: Case Report and Review of the CPR Literature

Cardiopulmonary resuscitation is taught widely to both lay persons and health care oworkers. It is a challenging psychomotor skill. Concerns about its safety to the rescuer have centered around the risk of infectious disease exposure. A young nursing assistant developed a minimally symptomatic pneumothorax during CPR training. This case is the first reported example of this complication for a CPR trainee or provider. The literature is reviewed for complications for CPR provider and recipient and the relevant issues regarding the current status and future direction of this intervention.

The effect of basic life support education on laypersons' willingness in performing bystander hands only cardiopulmonary resuscitation

BACKGROUND

Recently, hands only CPR (cardiopulmonary resuscitation) has been proposed as an alternative to standard CPR for bystanders. The present study was performed to identify the effect of basic life support (BLS) training on laypersons' willingness in performing standard CPR and hands only CPR.

METHODS

The participants for this study were non-medical personnel who applied for BLS training program that took place in 7 university hospitals in and around Korea for 6 months. Before and after BLS training, all the participants were given questionnaires for bystander CPR, and 890 respondents were included in the final analyses.

RESULTS

Self-assessed confidence score for bystander CPR, using a visual analogue scale from 0 to 100, increased from 51.5+/-30.0 before BLS training to 87.0+/-13.7 after the training with statistical significance (p 0.001). Before the training, 19% of respondents reported willingness to perform standard CPR on a stranger, and 30.1% to perform hands only CPR. After the training, this increased to 56.7% of respondents reporting willingness to perform standard CPR, and 71.9%, hands only CPR, on strangers. Before and after BLS training, the odds ratio of willingness to perform hands only CPR versus standard CPR were 1.8 (95% CI 1.5-2.3) and 2.0 (95% CI 1.7-2.6) for a stranger, respectively. Most of the respondents, who reported they would decline to perform standard CPR, stated that fear of liability and fear of disease transmission were deciding factors after the BLS training.

CONCLUSIONS

The BLS training increases laypersons' confidence and willingness to perform bystander CPR on a stranger. However, laypersons are more willing to perform hands only CPR rather than to perform standard CPR on a stranger regardless of the BLS training.

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 and compressions 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) and the second group received compression only CPR instructions (COCPR). Subjects performed CPR on a Laerdal Resusci-Anne CPR manikin and recording strips were analyzed for frequency and quality measures. Pre-and post-test questionnaires assessed subject fatigue and telephone instruction understanding. The primary outcome was the time interval from 911 call to initiation of chest compressions. Analysis included Student t-test, Chi-square, and Wilcoxon 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), and paused 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.

Marketing defibrillation training programs and bystander intervention support

This exploratory study identifies perceptions of and participation in resuscitation training programs, and bystanders' willingness to resuscitate cardiac arrest victims. While most of the study's participants greatly appreciate the importance of saving someone's life, many indicated that they did not feel comfortable assuming this role. The findings also demonstrate there is a relationship between type of victim and bystanders' willingness to intervene. Yet, bystander intervention discomfort can be overcome with cardiopulmonary resuscitation and defibrillation training, particularly when the victim is a coworker or stranger. Further implications of these findings are discussed and modifications to public access defibrillation (PAD) training programs' strategy and communications are proposed.

Cardiopulmonary resuscitation and pediatric advanced life support update for the emergency physician

Although pediatric cardiopulmonary arrest is uncommon, out-of-hospital survival is dismal. Through international consensus conferences, the American Heart Association develops new treatment recommendations for cardiopulmonary resuscitation every few years. The recent changes in cardiopulmonary resuscitation and pediatric advanced life support, with some background information about these changes, will be reviewed.

Poor quality teaching in lay person CPR courses

Recent studies have found that poor cardiopulmonary resuscitation (CPR) is commonly performed in resuscitation attempts, both by health professionals and lay people. One of the contributing factors to poor performance of CPR may be poor initial teaching. This study was conducted to investigate the quality of 14 CPR courses complying with New Zealand Qualifications Authority standards, which includes formal assessment of CPR. While courses taught by the large first aid training organisations in New Zealand had a student to manikin ratio of around 3:1, courses taught by smaller providers had a ratio of over 4:1. During the 4h course, only 20+/-2 min were spent demonstrating CPR, and 26+/-4 min were spent with students practising CPR. The assessment of adult, child and infant CPR took on average less than 2.5 min in total. Importantly, in the majority of courses (71%), certification was granted when the CPR technique was performed incorrectly, with both compression depth and compression place being corrected only 57% of the time. Courses only discussed the importance of early defibrillation 57% of the time, and provided limited information on symptoms of acute coronary syndromes. In light of these observations it is suggested that the current style of teaching is unlikely to result in students being able to perform adequate CPR if required in the community.

CPR training and CPR performance: do CPR-trained bystanders perform CPR?

OBJECTIVES

To determine factors associated with cardiopulmonary resuscitation (CPR) provision by CPR-trained bystanders and to determine factors associated with CPR performance by trained bystanders.

METHODS

The authors performed a prospective, observational study (January 1997 to May 2003) of individuals who called 911 (bystanders) at the time of an out-of-hospital cardiac arrest. A structured telephone interview of adult cardiac-arrest bystanders was performed beginning two weeks after the incident. Elements gathered during interviews included bystander and patient demographics, identifying whether the bystander was CPR trained, when and by whom the CPR was performed, and describing the circumstances of the event. If CPR was not performed, we asked the bystanders why CPR was not performed. Logistic regression was used to calculate odds ratios and 95% confidence intervals (95% CI) for factors associated with CPR performance.

RESULTS

Of 868 cardiac arrests, 684 (78.1%) bystander interviews were completed. Of all bystanders interviewed, 69.6% were family members of the victims, 36.8% of the bystanders had more than a high-school education, and 54.1% had been taught CPR at some time. In 21.2% of patients, the bystander immediately started CPR, and in 33.6% of cases, someone started CPR before the arrival of emergency medical services (EMS). Important overall predictors of CPR performance were the following: witnessed arrest (OR = 2.3; 95% CI = 1.4 to 3.8); bystander was CPR trained (OR = 6.6; 95% CI = 3.5 to 12.5); bystander had more than a high-school education (OR = 2.0; 95% CI = 1.2 to 3.1), or arrest occurred in a public location (OR = 3.1; 95% CI = 1.7 to 5.8). These variables were significant predictors of CPR performance among CPR-trained bystanders, as was CPR training within five years (OR = 4.5; 95% CI = 2.8 to 7.3). Common reasons that the CPR-trained bystanders cited for not performing CPR were the following: 37.5% stated that they panicked, 9.1% perceived that they would not be able to do CPR correctly, and 1.1% thought that they would hurt the patient. Surprisingly, only 1.1% objected to performing mouth-to-mouth resuscitation.

CONCLUSIONS

A minority of CPR-trained bystanders performed CPR. CPR provision was more common in CPR-trained bystanders with more than a high-school education and when CPR training had been within five years. Previously espoused reasons for not doing CPR (mouth-to-mouth, infectious-disease risk) were not the reasons that bystanders cited for not doing CPR. Further work is needed to maximize CPR provision after CPR training.

The role of carbon dioxide detectors for confirmation of endotracheal tube position

There is evidence that practitioners who are responsible for airway management at newborn resuscitations may place an endotracheal tube incorrectly with confidence. Moving on to the further stages of resuscitation, without managing the airway adequately, and commencing ventilation has the potential for significant harm to the baby. Because primary confirmation is fallible, there is a need for secondary confirmation of correct endotracheal tube placement and effective airway and breathing before moving on to cardiovascular support. Symmetric chest movement, auscultation, exhaled carbon dioxide (CO(2)), and an increase in heart rate have been suggested as providing secondary confirmation. Measurement of exhaled CO(2) is accepted widely as a standard of care in adult and pediatric intensive care and in anaesthetized patients.

Optimum cardiopulmonary resuscitation for basic and advanced life support: a simulation study

Optimum cardiopulmonary resuscitation (CPR) for both basic and advanced cardiac life support depends on a compromise between the number of chest compressions delivered and the amount of ventilation provided. This study used theoretical models of blood flow and both arterial and venous blood gas values to investigate the influence of different compression to ventilation ratios on CPR efficiency, as well as the effects of different inspired oxygen concentrations. With mouth-to-mouth ventilation, greater numbers of compressions between each ventilation provided progressively greater blood flow. However, a greater the number of compressions, reduced the arterial oxygen levels and carbon dioxide clearance. There was an optimum ratio, in terms of both oxygen delivery and carbon dioxide clearance, of around 20:1 compressions to ventilation. Optimum oxygen delivery was 0.19 L/min at 20:1, which was better than the oxygen delivery for standard CPR based on a ratio of 15:2 (0.13 L/min). When patients were ventilated with supplemental oxygen (either 50 or 85%) the lungs rapidly became saturated with oxygen, and oxygen delivery depended more on blood flow. Higher numbers of compressions provided greater oxygen delivery, but at the cost of increasing hypercarbia, which is thought to affect resuscitation success rates adversely. The simulation results suggested ratios around 20:1 would be the best compromise between blood flow, oxygen delivery (0.25 L/min) and avoidance of hypercarbia. The best results were provided by continuous chest compressions and simultaneous, asynchronous ventilation in an intubated patient. Arterial and venous oxygen and carbon dioxide levels were well maintained, with very good oxygen delivery (0.32 L/min). Intubation with continuous chest compressions and asynchronous ventilation can therefore significantly improve the quality of CPR as a whole, and not just ventilation.

Skeletal chest injuries secondary to cardiopulmonary resuscitation

OBJECTIVE

To review the evidence on the incidence of rib and sternal fractures after conventional closed-chest compression in the treatment of cardiac arrest in adults and children, and after active compression-decompression cardiopulmonary resuscitation (ACD-CPR).

METHODS

Medline search and additional review of the cited literature in the articles found.

RESULTS

Reports on conventional CPR in adults suggest an incidence of rib fractures ranging from 13 to 97%, and of sternal fractures from 1 to 43%. Reports on CPR in children suggest an incidence of rib fractures of 0-2%, and no sternal fractures. ACD-CPR has been reported as causing rib fractures in 4-87%, and sternal fractures in 0-93% of cases.

CONCLUSIONS

Sound methodological studies on thoracic fractures due to chest compression do not exist and the available studies cannot be compared one with another. In infants and toddlers, manual CPR rarely causes skeletal chest injuries. In adults, sternal fractures occur in at least one-fifth and rib fractures as well as rib and/or sternal fractures in at least one-third of the patients during conventional CPR. There is no compelling evidence to show that an increased complication rate is associated with ACD-CPR. Rib or sternal fractures are unlikely to increase mortality, as they rarely cause severe internal organ damage. Further prospective studies are desirable to assess complications by post-mortem examinations that explicitly address them. In particular, clinical evaluation of mechanical CPR devices should be accompanied by a thorough assessment of the associated complications because data specific to this modality are not available.

Arterial blood gases with 700 ml tidal volumes during out-of-hospital CPR

The optimal tidal and minute ventilation during cardiopulmonary resuscitation (CPR) is not known. In the present study seven adult, non-traumatic, out-of-hospital cardiac arrest patients were intubated and mechanically ventilated at 12 min(-1) with 100% oxygen and a tidal volume of 700 ml (10 +/- 2 ml kg(-1)). Arterial blood gas samples were analysed after 6-8 min of unsuccessful resuscitation and mechanical ventilation. Mean PaCO2 was 5.2 +/- 1.3 kPa and mean PaO2 30.7 +/- 17.2 kPa. The patient with the highest (14 ml kg(-1)) and lowest (8 ml kg(-1)) tidal volumes per kg had the lowest and highest PaCO2 values of 2.6 and 6.8 kPa, respectively. Linear regression analysis confirmed a significant correlation between arterial pCO2 and tidal volume in ml/kg, r2 = 0.87. We conclude that aiming for an estimated ventilation of 10 ml kg(-1) tidal volume at frequency of 12 min(-1) might be expected to achieve normocapnia during ALS.

Oxygen delivery and return of spontaneous circulation with ventilation:compression ratio 2:30 versus chest compressions only CPR in pigs

The need for rescue breathing during the initial management of sudden cardiac arrest is currently being debated and reevaluated. The present study was designed to compare cerebral oxygen delivery during basic life support (BLS) by chest compressions only with chest compressions plus ventilation in pigs with an obstructed airway mimicked by a valve hindering passive inhalation. Resuscitability was then studied during the subsequent advanced life support (ALS) period. After 3 min of untreated ventricular fibrillation (VF) BLS was started. The animals were randomised into two groups. One group received chest compressions only. The other group received ventilations and chest compressions with a ratio of 2:30. A gas mixture of 17% oxygen and 4% carbon dioxide was used for ventilation during BLS. After 10 min of BLS, ALS was provided. All six pigs ventilated during BLS attained a return of spontaneous circulation (ROSC) within the first 2 min of advanced cardiopulmonary resuscitation (CPR) compared with only one of six compressions-only pigs. While all except one compressions-only animal achieved ROSC before the experiment was terminated, the median time to ROSC was shorter in the ventilated group. With a ventilation:compression ratio of 2:30 the arterial oxygen content stayed at 2/3 of normal, but with compressions-only, the arterial blood was virtually desaturated with no arterio-venous oxygen difference within 1.5-2 min. Haemodynamic data did not differ between the groups. In this model of very ideal BLS, ventilation improved arterial oxygenation and the median time to ROSC was shorter. We believe that in cardiac arrest with an obstructed airway, pulmonary ventilation should still be strongly recommended.

Trials of teaching methods in basic life support (4): comparison of simulated CPR performance at unannounced home testing after conventional or staged training

This study compares the retention of basic life support (BLS) skills after 6 and 12 months by lay persons trained either in a conventional manner, or using a staged approach. Three classes, each of 2h, were offered to volunteers over a period of 4 months. For the conventional group, the second and third classes consisted of review of skills. Those in the staged group were first taught chest compression alone; chest compression with ventilation in a ratio of 50:5 was introduced at the second class; full standard CPR was taught at the third class. A total of 495 volunteers entered the study, 262 being randomly allocated to conventional training, and 233 to staged training. More of those who received staged training attended a second (78 volunteers) and third class (41 volunteers), compared with those who received conventional training (36 and 17, respectively). The objective of this study, however, was to compare the strategies of the different training methods. A total of 291 volunteers (167 conventional and 124 staged training) were available for unannounced home testing of full conventional CPR 6 months after initial training, and 260 volunteers (135 conventional and 125 staged training) were tested at 12 months. At 6 months, those taught by the staged method were significantly better at time to first compression (P < 0.0001), compression rate (P = 0.024), and hand position (P = 0.0001). At 12 months, those taught by the staged method were significantly better at shouting for help (P = 0.005), time to first compression (P < 0.0001), and compression depth (P = 0.003). Those taught conventionally were significantly better at checking for a carotid pulse at both 6 and 12 months (P < 0.0001). These results suggest that training lay persons in basic life support skills using a staged approach leads to overall better skill retention at 6 and 12 months, and has other advantages including a greater willingness to re-attend follow-up classes.

Quality of CPR with three different ventilation:compression ratios

Current adult basic cardiopulmonary resuscitation (CPR) guidelines recommend a 2:15 ventilation:compression ratio, while the optimal ratio is unknown. This study was designed to compare arterial and mixed venous blood gas changes and cerebral circulation and oxygen delivery with ventilation:compression ratios of 2:15, 2:50 and 5:50 in a model of basic CPR. Ventricular fibrillation (VF) was induced in 12 anaesthetised pigs, and satisfactory recordings were obtained from 9 of them. A non-intervention interval of 3 min was followed by CPR with pauses in compressions for ventilation with 17% oxygen and 4% carbon dioxide in a randomised, cross-over design with each method being used for 5 min. Pulmonary gas exchange was clearly superior with a ventilation:compression ratio of 2:15. While the arterial oxygen saturation stayed above 80% throughout CPR for 2:15, it dropped below 40% during part of the ventilation:compression cycle for both the other two ratios. On the other hand, the ratio 2:50 produced 30% more chest compressions per minute than either of the two other methods. This resulted in a mean carotid flow that was significantly higher with the ratio of 2:50 than with 5:50 while 2:15 was not significantly different from either. The mean cerebrocortical microcirculation was approximately 37% of pre-VF levels during compression cycles alone with no significant differences between the methods. The oxygen delivery to the brain was higher for the ratio of 2:15 than for either 5:50 or 2:50. In parallel the central venous oxygenation, which gives some indication of tissue oxygenation, was higher for the ratio of 2:15 than for both 5:50 and 2:50. As the compressions were done with a mechanical device with only 2-3 s pauses per ventilation, the data cannot be extrapolated to laypersons who have great variations in quality of CPR. However, it might seem reasonable to suggest that basic CPR by professionals should continue with ratio of 2:15 at present if it can be shown that similar brief pauses for ventilation can be achieved in clinical practice.

A randomized controlled trial of chest compression only CPR for older adults-a pilot study

Older people are trained infrequently in cardiopulmonary resuscitation (CPR), yet are more likely to witness a cardiac arrest. Older people who are CPR trained perform CPR when witnessing a cardiac arrest.

OBJECTIVE

To assess whether elderly adults (>55 years) who receive chest-compression only cardiopulmonary resuscitation (CC-CPR) training display equivalent skill retention rates compared with those who receive traditional CPR instruction. We also identified factors associated with 3 months skill retention at 3 months in both groups.

METHODS

Older adults in a suburban hospital Older Adult Services program were invited to participate in an experimental CPR course. The 2 h course was modelled after the AHA Friends and Family course, and used one of two standardized video scenarios. Seventy four subjects were randomized to CC-CPR (n=36) or traditional CPR (n=38) training. Participation consisted of initial training, followed by a 3 months return videotaped assessment. Three months skill competence was assessed either by consensus between two video evaluators, or the on-site evaluator. Chi square and Kappa tests were used for analysis, and unadjusted odds ratios and 95% confidence intervals are reported.

RESULTS

Skill retention assessments were completed on 29 (81%) CC-CPR and 26 (68%) CPR trainees. Subjects were elderly (71.5+/-6.69 years), and had a high rate of previous CPR training (58.0%). Groups were similar in demographic characteristics. After training, participants exhibited high rates of perceived competence (86.4%), although the overall 3 months skill retention was low (43.6%). CC-CPR training resulted in equivalent skill retention rates as compared with traditional CPR training (51.7 vs. 44.4%; P=0.586). No participant factors were associated with skill retention, including age, previous CPR training, education level, medical history, or perceived physical ability to perform.

CONCLUSION

We identified low rates of CPR skill retention in this elderly population. CC-CPR instruction was associated with equivalent skill retention rates compared with traditional CPR instruction. No demographic factors were associated with successful skill retention.

Knowledge of basic life support: a pilot study of the Turkish population by Baskent University in Ankara

A total of 494 participants who were scheduled to take Baskent University's basic life support (BLS) training programme in 2001-02 were asked to complete a 25-item questionnaire prior to the course. The questionnaire investigated the demographic characteristics of the subjects, their knowledge of the theoretical and practical aspects of BLS, and personal experience and attitudes related to BLS. The 'non-medical group' included 179 laypersons, and the 'medical group' was composed of medical students (n=220), residents (n=69) and clinical nurses (n=26). One-hundred and twenty-six (25.5%) of the participants had an encounter with some form of medical emergency event in their past and 207 (41.9%) had taken a BLS course previously. The most commonly cited anxiety about performing BLS was the fear of further harming the victim (56.9%). Nine of the participants said they would not perform mouth-to-mouth ventilation (1.8%). Compared to the other participants, individuals with previous emergency experience, and those who had previous BLS training answered significantly more of the theoretical questions correctly. However, neither of these groups performed significantly better than the other participants in the practical questions (P>0.05 for both comparisons). Based on our findings, we recommend that BLS training for medical undergraduates, other medical personnel and laypersons be improved and standardized throughout Turkey.

Temporal coordination of pharyngeal and laryngeal dynamics with breathing during swallowing: single liquid swallows

The critical integration of timing and patterning between respiratory and swallowing events was studied with simultaneous videofluoroscopic and respiratory recording during single liquid swallows. Respiratory phase patterns and the onsets and durations of 12 predetermined swallowing events and associated respiratory activities were studied. Results showed four highly repeatable, temporally oriented sequences (clusters) of swallowing and related respiratory events. Two respiratory phase patterns were identified without statistically significant differences in frequency of occurrence between age, gender, or race. These findings will aid in the identification of normal and abnormal patterns of breathing and swallowing in patients with dysphagia.

Optimum compression to ventilation ratios in CPR under realistic, practical conditions: a physiological and mathematical analysis

OBJECTIVE

To develop and evaluate a practical formula for the optimum ratio of compressions to ventilations in cardiopulmonary resuscitation (CPR). The optimum value of a variable is that for which a desired result is maximized. Here the desired result is assumed to be either oxygen delivery to peripheral tissues or a combination of oxygen delivery and waste product removal.

METHOD

Equations describing oxygen delivery and blood flow during CPR as functions of the number of compressions and the number of ventilations delivered over time were developed from principles of classical physiology. These equations were solved explicitly in terms of the compression/ventilation ratio and evaluated for a wide range of conditions using Monte Carlo simulations.

RESULTS

As the compression to ventilation ratio was increased from 0 to 50 or more, both oxygen delivery and the combination of oxygen delivery with blood flow increased to maximum values and then gradually declined. For variables typical of standard CPR as taught and specified in international guidelines, maximum values occurred at compression/ventilation ratios near 30:2. For variables typical of actual lay rescuer performance in the field, maximal values occurred at compression/ventilation ratios near 60:2.

CONCLUSION

Current guidelines overestimate the need for ventilation during standard CPR by two to four-fold. Blood flow and oxygen delivery to the periphery can be improved by eliminating interruptions of chest compression for these unnecessary ventilations.

An improved pocket rescue mask incorporating a novel visual breathing indicator

The difficulties inherent in the 'Look, Listen and Feel' method of identifying respiratory arrest prompted the authors to develop a simple mechanical breathing indicator that can show clearly, at a glance, whether or not a patient is breathing. The novel indicator was designed to be highly visible so that its interpretation should be obvious to medical personnel and the lay public, and yet sufficiently simple so that it could be easily and inexpensively incorporated into the type of pocket rescue masks currently in use. The indicator needs no power source, works indoors and outdoors and does not interfere with the delivery of rescue breaths during resuscitation. A prototype of the improved pocket mask incorporating the new indicator was made and was tested for its ability to detect breaths over a range of inspiratory flow rates and inspiratory pressures. The authors found that the indicator responded to peak inspiratory flow rates of between 15 and 120 l/min, inspiratory pressures as low as 0.18 cm H(2)O with no supplemental oxygen flowing to the mask and 0.22 cm H(2)O with supplemental oxygen flowing at 9 l/min, minute ventilation volumes between 7.1 and 21.8 l/min, tidal volumes between 0.36 and 2.92 l and a respiratory rate range of 7-24 breaths per min. The authors conclude that the new indicator, when attached to a pocket rescue mask, is sensitive enough to identify clearly and reliably those patients at the scene of collapse who have stopped breathing. Additionally it may assist rescuers in timing the delivery of assisted rescue breaths in those patients with poor respiratory effort.

Randomised controlled trials of staged teaching for basic life support. 1. Skill acquisition at bronze stage

We have investigated a method of teaching community CPR in three stages instead of in a single session. These have been designated bronze, silver, and gold stages. The first involves only opening of the airway and chest compression with back blows for choking, the second adds ventilation in a ratio of compressions to breaths of 50:5, and the third is a conversion to conventional CPR. In a controlled randomised trial of 495 trainees we compared the performance in tests immediately after instruction of those who had received a conventional course and those who had had the simpler bronze level tuition. The tests were based on video recordings of simulated resuscitation scenarios and the readouts from recording manikins. Differences occurred as a direct consequence of ventilation being required in one group and not the other, some variation probably followed from unforeseen minor changes in the way that instruction was given, whilst others may have followed from the greater simplicity in the new method of training. A careful approach was followed by slightly more trainees in the conventional group whilst appreciably more in the bronze group remembered to shout for help (44% vs. 71%). A clear advantage was also seen for bronze level training in terms of those who opened the airway as taught (35% vs. 56%), for checking breathing (66% vs. 88%), and for mentioning the need to phone for an ambulance (21% vs. 32%). Little difference was observed in correct or acceptable hand position between the conventional group who were given detailed guidance and the bronze group who were instructed only to push on the centre of the chest. The biggest differences related to the number of compressions given. The mean delay to first compression was 63 s and 34 s, and the mean duration of pauses between compressions was 16 s and 9 s, respectively. Average performed rates were similar in the two groups, but more in the conventional group compressed too slowly whereas more in the bronze group compressed too rapidly. Observations were made for only three cycles of compression, but extrapolating these to the 8 min often considered a watershed for chances of survival for victims of cardiac arrest, an average of 308 compressions would be expected from those using conventional CPR compared with 675 for those using bronze level CPR. The implications of this difference are discussed.

Arterial blood-gases with 500- versus 1000-ml tidal volumes during out-of-hospital CPR

The correct tidal volume during cardiopulmonary resuscitation (CPR) is presently debated. While the European Resuscitation Council (ERC) and American Heart Association (AHA) previously recommended a tidal volume of 800-1200 ml, the ERC has recently reduced this to 400-600 ml. In a prospective, randomised study of 17 non-traumatic out-of-hospital cardiac arrest patients intubated and mechanically ventilated 12 min(-1) with 100% oxygen, we have therefore compared arterial blood gases generated with tidal volumes of 500 and 1000 ml. Mean time from cardiac arrest to arrival of the ambulance was 13+/-8 and 14+/-8 min in the two groups, respectively. Arterial blood samples were taken percutaneously 5 and 10-15 min after onset of the mechanical ventilation and analysed instantly. Pa(CO(2)) was significantly higher for a tidal volume of 500 than 1000 ml at both 5 and 10-15 min, 7.48+/-2.23 versus 3.70+/-0.83 kPa (P=0.002) and 7. 45+/-1.19 versus 3.98+/-1.58 kPa (P<0.001). The pH was lower for 500 than 1000 ml at 10-15 min, 7.01+/-0.10 versus 7.20+/-0.17 (P=0.034), with a strong trend in the same direction at 5 min (P=0.06). There was adequate oxygenation with no differences in Pa(O(2)) or BE at any time between the two groups, and no significant differences in any blood gas variables between the 5- and 10-15-min samples. We conclude that arterial normocapnia is not achieved with either tidal volume during advanced life support with non-rebreathing ventilation at 12 min(-1). What ventilation volume is required for CO(2) removal and oxygenation during basic life support with mouth-to-mouth ventilation cannot be extrapolated from the present data. In that situation the risk of gastric inflation, regurgitation and aspiration must also be taken into account.

Cardiopulmonary resuscitation performance of subjects over forty is better following half-hour video self-instruction compared to traditional four-hour classroom training

Cardiopulmonary resuscitation (CPR) training is not well targeted to family members of individuals at highest risk of cardiac arrest. Participants in traditional CPR classes (TRAD) average 31 years of age, while family members of cardiac patients average 55 years. Video self-instruction (VSI) can reach older individuals and others who do not participate in TRAD classes. VSI is a combination of a 34-min videotape and an inexpensive manikin intended for use in the home, where three-quarters of all out-of-hospital cardiac arrests occur. We exposed 202 subjects 40 years of age and older (mean age 59.4 years, S.D. = 10.9) to either TRAD or VSI, and tested them individually immediately following training rising validated methods including measurement by means of a Laerdal-Skillmeter manikin. According to American Heart Association (AHA) criteria, VSI subjects performed an average of 20.8% of all compressions and 25.1% of all ventilations correctly, compared with 3.4% of compressions and 1.7% of ventilations by TRAD subjects (P < 0.0001). VSI subjects performed an average of 10.1 of the total 14 CPR assessment and sequence skills correctly, compared with an average of 4.7 for TRAD (P < 0.0001). On a measure of overall performance, 62.7% of the VSI subjects were rated 'competent' or better (i.e. capable of performing CPR that 'would probably be effective'), compared to 6.1% of TRAD subjects (P < 0.0001). Only 17.8% of VSI subjects were rated as 'not competent' (i.e. unable to obtain a combination of any chest rise and any compression of the sternum) compared with 69.1% of TRAD subjects. VSI provides an effective, convenient, and inexpensive means of training persons over 40 years of age that achieves skill performance superior to TRAD.

Efficacy of chest compression-only BLS CPR in the presence of an occluded airway

Reluctance of the lay public to perform bystander CPR is becoming an increasingly worrisome problem in the USA. Most bystanders who admit such reluctance concede that fear of contagious disease from mouth-to-mouth contact is what keeps them from performing basic life support. Animal models of prehospital cardiac arrest indicates that 24-h survival is essentially as good with chest compression-only CPR as with chest compressions and assisted ventilation. This simpler technique is an attractive alternative strategy for encouraging more bystander participation. Such experimental studies have been criticized as irrelevant however secondary to differences between human and porcine airway mechanics. This study examined the effect of chest compression-only CPR under the worst possible circumstances where the airway was totally occluded. After 6 min of either standard CPR including ventilation with a patent airway or chest compressions-only with a totally occluded airway, no difference in 24 h survival was found (10/10 vs. 9/10). As anticipated arterial blood gases were not as good, but hemodynamics produced were better with chest compression-only CPR (P < 0.05). Chest compression-only CPR, even with a totally occluded airway, is as good as standard CPR for successful outcome following 6.5 min of cardiac arrest. Such a strategy for the first minutes of cardiac arrest, particularly before professional help arrives, has several advantages including increased acceptability to the lay public.

A rationale for staged teaching of basic life support

Basic life support is a crucial part of the Chain of Survival. Unfortunately, however the skill is complex and cannot readily be acquired--let alone retained--in the course of a single training session. Although the problem has long been recognised, no new strategies have been widely implemented to counter the problem. We believe that staged teaching of CPR might provide a solution, and we have devised a program to test this new method. It involves three stages of instruction that we have called bronze, silver, and gold standards. The bronze standard involves opening the airway and providing chest compression without active ventilation: this alone may widen the window of opportunity for successful defibrillation in adult victims in out-of-hospital cardiac arrest. Ventilation is introduced at silver stage using a ratio of 50:5, with emphasis on its value in the resuscitation of children being used as motivation to bring people back for a second period of instruction. The gold stage teaches conventional CPR. A pilot study has been encouraging and a randomized trial on skill acquisition and skill retention is planned.

Factors surrounding cardiopulmonary resuscitation influencing bystanders' psychological reactions

The incidence of Sweden's out-of-hospital cardiac arrests averages 10000 annually. Each year bystanders initiate cardiopulmonary resuscitation (CPR) approximately 2000 times prior to arrival of emergency medical service (EMS). The aim of this study was to identify factors influencing the bystanders psychological reactions to performing CPR. We mailed a questionnaire to all bystanders who reported performing CPR to the CPR Centre of Sweden from autumn 1992 to 1995. The study included 544 bystander reports. Nine factors were found to be associated with bystanders experience in a univariate analysis. Among these were victim outcome (p < 0.0001), CPR duration (p = 0.0009) and their experience of the attitude of the EMS personnel (p = 0.004). In a multivariate logistic regression model, lack of debriefing following the intervention (p = 0.0001) and fatal victim outcome (p = 0.03) were independent predictors of a negative bystander psychological reaction. The importance of having someone to talk to following an intervention and the EMS personnel concern for the rescuer should be emphasised. The goal should be that critical incident debriefing is available to every bystander following his or her CPR attempt.