Rethinking bystander CPR for out-of-hospital cardiac arrest

Citation

SOS-KANTO study group: Cardiopulmonary resuscitation by bystanders with chest compression only (SOS-KANTO): an observational study. Lancet 2007, 369:920–926 [1].

Background

Mouth-to-mouth ventilation is a barrier to bystanders doing cardiopulmonary resuscitation (CPR), but few clinical studies have investigated the efficacy of bystander resuscitation by chest compressions without mouth-to-mouth ventilation (cardiac-only resuscitation).

Methods

Objective

To compare the effect of bystander-provided cardiac-only resuscitation to conventional CPR in adults who had out-of-hospital cardiac arrest.

Design

Prospective multicenter observational study.

Setting

58 emergency hospitals and emergency medical service units in the Kanto region of Japan.

Subjects

Patients with witnessed out-of-hospital cardiac arrest who were subsequently transported by paramedics to participating emergency hospitals. Exclusion criteria were age <18 years, further cardiac arrest after the arrival of paramedics, documented terminal illness, presence of a do-not-resuscitate order, and bystander resuscitation without documented chest compressions.

Intervention

None. On arrival at the scene, paramedics assessed the technique of bystander resuscitation, recording it as conventional CPR (chest compressions with mouth-to-mouth ventilation), cardiac-only resuscitation (chest compressions alone), or no bystander CPR. Patients were followed and revaluated 30 days after the arrest to determine neurologic status.

Outcome

The primary endpoint was favorable neurological outcome 30 days after cardiac arrest using the Glasgow-Pittsburgh cerebral-performance scale, with favorable neurological outcome defined as a category 1 (good performance) or 2 (moderate disability) on a 5-point scale.

Results

4068 adult patients who had out-of-hospital cardiac arrest witnessed by bystanders were included; 439 (11%) received cardiac-only resuscitation from bystanders, 712 (18%) conventional CPR, and 2917 (72%) received no bystander CPR. Any resuscitation attempt was associated with a higher proportion having favorable neurological outcomes than no resuscitation (5.0%vs 2.2%, p < 0.0001). Cardiac-only resuscitation resulted in a higher proportion of patients with favorable neurological outcomes than conventional CPR in patients with apnea (6.2%vs 3.1%; p = 0.0195), with shockable rhythm (19.4%vs 11.2%, p = 0.041), and with resuscitation that started within 4 min of arrest (10.1%vs 5.1%, p = 0.0221). However, there was no evidence for any benefit from the addition of mouth-to-mouth ventilation in any subgroup. The adjusted odds ratio for a favorable neurological outcome after cardiac-only resuscitation was 2.2 (95% CI 1.2–4.2) in patients who received any resuscitation from bystanders.

Conclusion

Cardiac-only resuscitation by bystanders is the preferable approach to resuscitation for adult patients with witnessed out-of-hospital cardiac arrest, especially those with apnea, shockable rhythm, or short periods of untreated arrest.     

The willingness of final year medical and dental students to perform bystander cardiopulmonary resuscitation in an Asian community

Background

Despite the importance of early effective chest compressions to improve the chance of survival of an out-of-hospital cardiac arrest victim, it is still largely unknown how willing our Malaysian population is to perform bystander cardiopulmonary resuscitation (CPR).

Aims

We conducted a voluntary, anonymous self-administered questionnaire survey of a group of 164 final year medical students and 60 final year dental students to unravel their attitudes towards performing bystander CPR.

Methods

Using a 4-point Likert scale of “definitely yes,” “probably yes,” “probably no,” and “definitely no,” the students were asked to rate their willingness to perform bystander CPR under three categories: chest compressions with mouth-to-mouth ventilation (CC + MMV), chest compressions with mask-to-mouth ventilation (CC + PMV), and chest compressions only (CC). Under each category, the students were given ten hypothetical victim scenarios. Categorical data analysis was done using the McNemar test, chi-square test, and Fisher exact test where appropriate. For selected analysis, “definitely yes” and “probably yes” were recoded as a “positive response.”

Results

Generally, we found that only 51.4% of the medical and 45.5% of the dental students are willing to perform bystander CPR. When analyzed under different hypothetical scenarios, we found that, except for the scenario where the victim is their own family member, all other scenarios showed a dismally low rate of positive responses in the category of CC + MMV, but their willingness was significantly improved under the CC + PMV and CC categories.

Conclusion

This study shows that there are unique sociocultural factors that contribute to the reluctance of our students to perform CC + MMV.     

Pediatric basic life support

The new international consensus and guidelines were published by American Heart Association in October 2010. These guidelines include many important changes in pediatric basic life support(BLS) based on many evidences. Especially in children, asphyxial cardiac arrest has been more common than cardiac arrest and only one third to one half victims can receive bystander cardiopulmonary resuscitation(CPR). According to new guidelines, "CAB" (Chest compressions/Circulation, Airway, and Breathing/ventilation) is recommended instead of "ABC" sequence. In addition, pediatric chain of survival is revised and the section of "Look, Listen, Feel" is deleted. These changes are recommended in order to simplify training with the hope that more pediatric victims will consequently receive bystander CPR.     

Clinical and hemodynamic comparison of 15:2 and 30:2 compression-to-ventilation ratios for cardiopulmonary resuscitation

OBJECTIVE: To compare cardiopulmonary resuscitation (CPR) with a compression to ventilation (C:V) ratio of 15:2 vs. 30:2, with and without use of an impedance threshold device (ITD). DESIGN: Prospective randomized animal and manikin study. SETTING: Animal laboratory and emergency medical technician training facilities. SUBJECTS: Twenty female pigs and 20 Basic Life Support (BLS)-certified rescuers. INTERVENTIONS, MEASUREMENTS, AND MAIN RESULTS: ANIMALS: Acid-base status, cerebral, and cardiovascular hemodynamics were evaluated in 18 pigs in cardiac arrest randomized to a C:V ratio of 15:2 or 30:2. After 6 mins of cardiac arrest and 6 mins of CPR, an ITD was added. Compared to 15:2, 30:2 significantly increased diastolic blood pressure (20 +/- 1 to 26 +/- 1; p < .01); coronary perfusion pressure (18 +/- 1 to 25 +/- 2; p = .04); cerebral perfusion pressure (16 +/- 3 to 18 +/- 3; p = .07); common carotid blood flow (48 +/- 5 to 82 +/- 5 mL/min; p < .001); end-tidal CO2 (7.7 +/- 0.9 to 15.7 +/- 2.4; p < .0001); and mixed venous oxygen saturation (26 +/- 5 to 36 +/- 5, p < .05). Hemodynamics improved further with the ITD. Oxygenation and arterial pH were similar. Only one of nine pigs had return of spontaneous circulation with 15:2, vs. six of nine with 30:2 (p < 0.03). HUMANS: Fatigue and quality of CPR performance were evaluated in 20 BLS-certified rescuers randomized to perform CPR for 5 mins at 15:2 or 30:2 on a recording CPR manikin. There were no significant differences in the quality of CPR performance or measurement of fatigue. Significantly more compressions per minute were delivered with 30:2 in both the animal and human studies. CONCLUSIONS: These data strongly support the contention that a ratio of 30:2 is superior to 15:2 during manual CPR and that the ITD further enhances circulation with both C:V ratios.     

Impact of adding video communication to dispatch instructions on the quality of rescue breathing in simulated cardiac arrests--a randomized controlled study

OBJECTIVE: Both ventilations and compressions are important for victims of prolonged cardiopulmonary resuscitation (CPR) and asphyxial arrest. Dispatch assistance increases bystander CPR, but the quality of dispatcher-assisted CPR (DA-CPR), especially rescue breathing, remains unsatisfactory. This study was conducted to assess the impact of adding interactive video communication to dispatch instructions on the quality of rescue breathing in simulated cardiac arrests. METHODS: In this simulation-based study, adults without CPR training within 5 years were recruited between April and July 2007 and randomized to receive dispatch assistance with either voice instruction alone (voice group, n=53) or interactive voice and video instruction (video group, n=43) via a video cell phone. The quality of rescue breathing was evaluated by reviewing the videos and mannequin reports. RESULTS: Subjects in the video group were more likely to open the airway correctly (95.3% vs. 58.5%, P<0.01) and to lift the chin properly (95.3% vs. 62.3%, P<0.01), but had similar rates of head-tilt (95.3% vs. 84.9%, P=0.10). Volunteers in the video group had larger volume of ventilation (median volume 540ml vs. 0ml, P<0.01), greater possibility to sustain an open airway (88.4% vs. 60.4%, P<0.01) and a tendency towards better nose-pinch (97.7% vs. 86.8%, P=0.06). The video group spent longer time to open the airway (59s vs. 56s, P<0.05) and to give the first rescue breathing (139s vs. 102s, P<0.01). CONCLUSION: Adding video communication to dispatch instructions improved the quality of bystander rescue breathing, including higher proportion of airway opened, and larger volume of ventilation delivered, in simulated cardiac arrests.     

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.     

Use of intraosseous blood to assess blood chemistries and hemoglobin during cardiopulmonary resuscitation with drug infusions.

OBJECTIVE: To compare intraosseous with central venous blood samples for biochemical analyses and hemoglobin levels during cardiopulmonary resuscitation (CPR) and during cardiopulmonary resuscitation with infusion of sodium bicarbonate, epinephrine, and saline boluses through the intraosseous site. DESIGN: Prospective, complete repeated measures study. SETTING: An animal laboratory at a university medical center. SUBJECTS: Thirty-two piglets (mean weight, 30 [range, 24-35] kg). INTERVENTIONS: Animals were anesthetized, instrumented, and subjected to hypoxic cardiac arrest. An intraosseous cannula was inserted into the tibia, and animals were randomly assigned to one of five groups: heparinized saline (n = 6), epinephrine infusions only (n = 6), saline infusions only (n = 6), sodium bicarbonate infusions only (n = 8), and epinephrine, saline, and sodium bicarbonate infusions through the same site (n = 6). CPR (chest compressions and mechanical ventilation) was performed in all groups. Simultaneous blood samples were taken from the central venous and intraosseous sites before arrest and after 5 and 30 mins of CPR. MEASUREMENTS AND MAIN RESULTS: There were no differences (p < .05) in sodium, potassium, magnesium, lactate, and calcium values of intraosseous and central venous blood at the baseline and during 5 mins of CPR with infusions through the intraosseous cannula. At 30 mins, differences were apparent in magnesium, potassium, and sodium values between groups when the intraosseous cannula was used for infusions as well as sampling. Intraosseous potassium, glucose, and magnesium values were lower and sodium values were higher than central venous blood levels. No differences were seen at all sampling intervals if small-volume heparinized saline was given through the intraosseous site. Hemoglobin values were lower in the intraosseous group after 30 mins of CPR and infusions through the intraosseous site. After 30 mins of CPR, all hemoglobin values from the intraosseous site were <10 g/100 mL. CONCLUSION: Intraosseous and central venous blood biochemical and hemoglobin values were similar during hemodynamic stability and throughout 30 mins of resuscitation if no drugs were given through the intraosseous site. However, differences existed after 30 mins of CPR and infusions through the intraosseous site. Laboratory values may be erroneous when intraosseous blood is used during periods of resuscitation of >5 mins if drugs and fluid boluses have also been infused through the site. For reliable values, an intraosseous site for sampling only may be reasonable.     

Compression-only CPR—To teach or not to teach?

There is mounting evidence to support the concept of chest compression-only CPR for out-of-hospital cardiac arrest victims, not least because it is simple and does not require rescuers to perform unpleasant mouth-to-mouth ventilation. The problem is that for a small, but important, minority of victims (children and those suffering an asphyxial or prolonged arrest) this is suboptimal treatment.     

Increased chest compression to ventilation ratio improves delivery of CPR

OBJECTIVE: Chest compressions are interrupted during cardiopulmonary resuscitation (CPR) due to human error, for ventilation, for rhythm analysis and for rescue shocks. Earlier data suggest that the recommended 15:2 compression to ventilation (C:V) ratio results in frequent interruptions of compressions during CPR. We evaluated a protocol change from the recommended C:V ratio of 15:2-30:2 during CPR in our municipal emergency medical system. METHODS: Municipal firefighters (N=875) from a single city received didactic and practical training emphasizing the importance of continuous chest compressions and recommending a 30:2 C:V ratio. Both before and after the training, digital ECG and voice records from all first-responder cases of out-of-hospital cardiac arrest were examined off-line to quantify chest compressions. The number of chest compressions delivered and the number and duration of pauses in chest compressions were compared by t-test for the first three 1min intervals when CPR was recommended. RESULTS: More compressions were delivered during minutes 1, 2, and 3 during CPR with the 30:2 C:V ratio (78+/-29, 80+/-30, 74+/-26) than with the 15:2C:V ratio (53+/-24, 57+/-24, 51+/-26) (p<0.001). Fewer pauses for ventilation occurred during each minute with the 30:2 C:V ratio (1.7+/-1.2, 2.2+/-1.2, 1.8+/-1.0) than with the 15:2C:V ratio (3.4+/-2.6, 4.7+/-7.2, 4.0+/-2.9) (p< or =0.01). Degradation of the final ECG to asystole occurred less frequently after the protocol change (asystole pre 67.1%, post 56.8%, p<0.05). The incidence of return of spontaneous circulation was not altered following the protocol change. CONCLUSIONS: Retraining first responders to use a C:V ratio of 30:2 instead of the traditional 15:2 during out-of-hospital cardiac arrest increased the number of compressions delivered per minute and decreased the number of pauses for ventilation. These data are new as they produced persistent and quantifiable changes in practitioner behavior during actual resuscitations.     

Comparison of chest compression only and standard cardiopulmonary resuscitation for out-of-hospital cardiac arrest in Singapore

OBJECTIVE: Chest compression only cardiopulmonary resuscitation (CC-CPR) without ventilation has been proposed as an alternative to standard cardiopulmonary resuscitation (CPR) for bystanders. However, there has been controversy regarding the relative effectiveness of both of these techniques. We aim to compare the outcomes of cardiac arrest patients in the cardiac arrest and resuscitation epidemiology study who either received CC-CPR, standard CPR or no bystander CPR. METHODS: This prospective cohort study involved all out-of-hospital cardiac arrest (OHCA) patients attended to by emergency medical service (EMS) providers in a large urban centre. The data analyses were conducted secondarily on these collected data. The technique of bystander CPR was reported by paramedics who arrived at the scene. RESULTS: From 1 October 2001 to 14 October 2004, 2428 patients were enrolled into the study. Of these, 255 were EMS-witnessed arrests and were excluded. 1695 cases did not receive any bystander CPR, 287 had standard CPR and 154 CC-CPR. Patient characteristics were similar in both the standard and CC-CPR groups except for a higher incidence of residential arrests and previous heart disease sufferers in the CC-CPR group. Patients who received standard CPR (odds ratio (OR) 5.4, 95% confidence interval (CI) 2.1-14.0) or CC-CPR (OR 5.0, 95% CI 1.5-16.4) were more likely to survive to discharge than those who had no bystander CPR. There was no significant difference in survival to discharge between those who received CC-CPR and standard CPR (OR 0.9, 95% CI 0.3-3.1). CONCLUSION: We found that patients were more likely to survive with any form of bystander CPR than without. This emphasises the importance of chest compressions for OHCA patients, whether with or without ventilation.     

Continuous chest compression resuscitation in arrested swine with upper airway inspiratory obstruction

Background

This study was designed to compare 24-h survival rates and neurological function of swine in cardiac arrest treated with one of three forms of simulated basic life support CPR.

Methods

Thirty swine were randomized equally among three experimental groups to receive either 30:2 CPR with an unobstructed endotracheal tube (ET) or continuous chest compression (CCC) CPR with an unobstructed ET or CCC CPR with a collapsable rubber sleeve on the ET allowing air outflow but completely restricting air inflow. The swine were anesthetized but not paralyzed. Two min of untreated VF was followed by 9 min of simulated single rescuer bystander CPR. In the 30:2 CPR group, each set of 30 chest compressions was followed by a 15-s pause to simulate the realistic duration of interrupted chest compressions required for a single rescuer to deliver 2 mouth-to-mouth ventilations. The other two groups were provided continuous chest compressions (CCC) without assisted ventilations. At 11 min post-arrest a biphasic defibrillation shock (150 J) was administered followed by a period of advanced cardiac life support.

Results

In the 30:2 group, 8 of 10 animals had good neurological function at 24-h post-resuscitation. In the CCC open airway group, 10 of 10, and in the CCC inspiratory obstructed group, 9 of 10. The number of shocks (P < 0.05) and epinephrine doses (P < 0.05) required for ROSC was greater in the 30:2 CPR group than in the other two groups.

Conclusions

There were no differences in 24-h survival with good neurological function among these three different CPR protocols.     

Vasopressin improves vital organ blood flow after prolonged cardiac arrest with postcountershock pulseless electrical activity in pigs

OBJECTIVE: Although a benefit of vasopressin when compared with epinephrine was shown during cardiopulmonary resuscitation (CPR) after a short duration of ventricular fibrillation cardiac arrest, the effect of vasopressin during prolonged cardiac arrest with pulseless electrical activity is currently unknown. DESIGN: Prospective, randomized laboratory investigation using an established porcine model with instrumentation for measurement of hemodynamic variables, vital organ blood flow, blood gases, and return of spontaneous circulation. SETTING: University hospital laboratory. SUBJECTS: Eighteen domestic pigs. INTERVENTIONS: After 15 mins of cardiac arrest and 3 mins of chest compressions, 18 animals were randomly treated with either 0.8 units/kg vasopressin (n = 9) or 200 microg/kg epinephrine (n = 9). MEASUREMENTS AND MAIN RESULTS: Compared with epinephrine, vasopressin resulted, at both 90 secs and 5 mins after drug administration, in significantly higher (p < .05) median (25th-75th percentiles) left ventricular myocardial blood flow (120 [range, 96-193] vs. 54 [range, 11-92] and 56 [range, 41-80] vs. 21 [range, 11-40] mL/min/100 g, respectively) and total cerebral blood flow (85 [78-102] vs. 24 [18-41] and 50 [44-52] vs. 8 [5-23] mL/min/100 g, respectively). Spontaneous circulation was restored in eight of nine animals in the vasopressin group and in one of nine animals in the epinephrine group (p = .003). CONCLUSIONS: Compared with a maximum dose of epinephrine, vasopressin significantly increased left ventricular myocardial and total cerebral blood flow during CPR and return of spontaneous circulation in a porcine model of prolonged cardiac arrest with postcountershock pulseless electrical activity.     

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.     

Continuous chest compressions improve survival and neurologic outcome in a swine model of prolonged ventricular fibrillation

Introduction

Evidence suggests that any interruptions, including those of rescue breaths, during cardiopulmonary resuscitation (CPR) have significant, detrimental effects on survival. The 2010 International Liaison Committee on Resuscitation guidelines strongly emphasized on the importance of minimizing interruptions during chest compressions. However, those guidelines also stress the need for ventilations in the case of prolonged cardiac arrest (CA), and it is not at present clear at which point of CA the necessity of providing ventilations overcomes the hemodynamic compromise caused by chest compressions' interruption.

Methods

Ventricular fibrillation was electrically induced in 20 piglets (19 ± 2 kg) and left untreated for 8 minutes. Animals were randomized to receive 2 minutes of either chest compression-only CPR (group CC) or standard 30:2 compressions/ventilations CPR (group S) before defibrillation. Resuscitated animals were monitored under anesthesia for 4 hours and then were awakened and placed in a maintenance facility for 24 hours.

Results

There was no significant difference among groups for both return of spontaneous circulation and 1-hour survival. There was a significant difference in 24-hour survival (group CC, 7/10 vs group S, 2/10; P = .025). Blood lactate levels were significantly lower in group CC compared with group S in both 1 (P = .019) and 4 hours (P = .034) after return of spontaneous circulation. Furthermore, group CC animals exhibited significantly higher mean Neurologic Alertness Score (58 ± 42.4 vs 8 ± 16.9) (P < .05).

Conclusion

In this swine CA model, where defibrillation was first attempted at 10 minutes of untreated ventricular fibrillation, uninterrupted chest compressions resulted in significantly higher survival rates and higher 24-hour neurologic scores, compared with standard 30:2 CPR.     

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.     

Hypercarbic acidosis reduces cardiac resuscitability

BACKGROUND AND METHODS: Marked increases in myocardial hypercarbia and acidosis accompany cardiac arrest and resuscitation. To investigate whether hypercarbic acidosis independent of oxygenation is of itself detrimental to cardiac resuscitation, three groups of six Sprague-Dawley rats were ventilated with gas mixtures containing concentrations of inspired CO2 (FICO2) of 0.0, 0.3, or 0.5, with oxygen fractions held constant at 0.5. After 4 mins of ventricular fibrillation, mechanical chest compressions were initiated with a pneumatic thumper; 2 mins later, transthoracic defibrillation was attempted. RESULTS: Each animal ventilated with FICO2 of 0.0 or 0.3 was successfully resuscitated. However, none of the animals ventilated with FICO2 of 0.5, in which aortic pH was less than 6.67 and aortic PCO2 was greater than 200 torr (greater than 26.7 kPa), was resuscitated (p less than .001). This finding contrasted with a second control group of seven identically treated animals which, in the absence of cardiac arrest, demonstrated no adverse effects after ventilation with an FICO2 of 0.5. CONCLUSIONS: Increases in FICO2 to levels of 0.5 under conditions of constant arterial oxygenation and controlled coronary perfusion pressure preclude successful resuscitation in this rodent model of CPR.     

Update on recommendations for adult basic cardiopulmonary resuscitation

One of the most urgent situations faced by nurses is cardiac arrest. Knowledge of cardiopulmonary resuscitation (CPR) is essential for survival after intra-or out-of-hospital cardiac arrest. Two of the main factors predicting survival after a cardiopulmonary arrest are the immediate start of CPR and early activation of the survival chain. In 2005 The European Resuscitation Council published new recommendations on CPR. The changes center on simplification of the protocol, giving greater importance to chest compressions than to mouth-to-mouth breath resuscitation. After checking that the victim is not breathing, 30 compressions must be immediately given. The first 2 rescue breaths and carotid pulse checking have been eliminated. The current recommended ratio of chest compressions-breaths is 30:2.     

A randomized cross-over study of the quality of cardiopulmonary resuscitation among females performing 30:2 and hands-only cardiopulmonary resuscitation

Background  

Hands-Only cardiopulmonary resuscitation (CPR) is recommended for use on adult victims of witnessed out-of-hospital (OOH) sudden cardiac arrest or in instances where rescuers cannot perform ventilations while maintaining minimally interrupted quality compressions. Promotion of Hands-Only CPR should improve the incidence of bystander CPR and, subsequently, survival from OOH cardiac arrest; but, little is known about a rescuer's ability to deliver continuous chest compressions of adequate rate and depth for periods typical of emergency services response time. This study evaluated chest compression rate and depth as subjects performed Hands-Only CPR for 10 minutes. For comparison purposes, each also performed chest compressions with ventilations (30:2) CPR. It also evaluated fatigue and changes in body biomechanics associated with each type of CPR.