Percentage Of Compressions Research Articles

Objective assessment of cardiopulmonary resuscitation skills of 10–11-year-old schoolchildren using two different external chest compression to ventilation ratios

To objectively evaluate how effectively children can perform cardiopulmonary resuscitation CPR) 2 months after a single, 2h training session and establish whether or not their performance is affected by the ratio of external chest compressions to ventilations used. Eighty-five schoolchildren aged 10-11 years old were given a 2-h CPR training programme. After 2 months they were randomised into two groups and asked to perform CPR on a resuscitation skills reporter manikin for 3min at a ratio of 30:2 followed by 5min rest, then for 3min at 15:2 (or vice versa). Chest compression depths and ventilation volumes were recorded on a laptop computer and analysed using the Hills and Armitage crossover trial design. The school children were found to be capable of performing effective CPR 2 months after a single training session. In both groups the percentage of chest compressions, of depth recommended by current CPR guidelines, was greater when the 15:2 ratio was being used (P<0.001). The average chest compression depth was significantly greater when the children were performing CPR at a ratio of 15:2 (P<0.001). The compression to ventilation ratio used did not affect the average volume or percentage of effective ventilations given. However, in both groups, the ventilation variables showed enhanced performance during the second period of CPR. Children as young as 10-11 years are capable of performing effective CPR after a single, 2h training session in cardiopulmonary resuscitation given in school. This age group are able to achieve greater depth of chest compressions, when using a ratio of 15:2 rather than 30:2.

Quality of cardiopulmonary resuscitation on manikins: On the floor and in the bed

Background: In general, in-hospital resuscitation is performed in a bed and out-of-hospital resuscitation on the floor. The surface under the patient may affect the cardiopulmonary resuscitation (CPR) quality; therefore, we evaluated CPR quality (the percentage of chest compressions of correct depth) and rescuer's fatigue (the mean compression depth minute by minute) when CPR is performed on a manikin on the floor or in the bed. Methods: Forty-four simulated cardiac arrest scenarios of 10 min were treated by intensive care unit (ICU) nurses in pairs using a 30 : 2 chest compression-to-ventilation ratio. The rescuer who performed the compressions was changed every 2 min. CPR was randomly performed either on the floor or in the bed without a backboard; in both settings, participants kneeled beside the manikin. Results: A total number of 1060 chest compressions, 44% with correct depth, were performed on the floor; 1068 chest compressions were performed in the bed, and 58% of these were the correct depth. These differences were not significant between groups. The mean compression depth during the scenario was 44.9±6.2 mm (mean±SD) on the floor and 43.0±5.9 mm in the bed (P=0.3). The mean chest compression depth decreased over time on both surfaces (P<0.001), indicating rescuer fatigue, but this change was not different between the groups (P=0.305). Conclusions: ICU nurses perform chest compression as effectively on the floor as in the bed. The mean chest compression depth decreases over time, but the surface had no significant effect.

A Failed Attempt to Improve Quality of Out-of-Hospital CPR Through Performance Evaluation

Introduction. Quality of CPR performed by professionals has been reported to be substandard even with automated corrective feedback. Our hypothesis was that providing CPR performance evaluation (CPR-PE) to three ambulance services would facilitate local education andimplementation of CPR guidelines and, consequently, improve CPR quality.Methods: Quality of CPR in 85 consecutive cases of adult out-of-hospital cardiac arrests after CPR-PE was compared to 39 cases prior to CPR-PE. Real-time automated verbal andvisual feedback on CPR performance was given in all cases. No general implementation strategy was provided because the sites were expected to use the CPR-PEs in development of local strategies. Because the strategies were expected to vary, the sites were analyzed separately.Results: No significant improvement was seen in quality of CPR after CPR-PE. No chest compressions were given 40% of the time before versus 41% after CPR-PE. The median (95% confidence interval) percentage of chest compressions within the recommended depth range (38–51 mm) was 35% (27–57) before versus 51% (42–60) after CPR-PE (p = 0.12). In site-specific analysis, chest compressions within guideline depth increased from 31% to 61% after CPR-PE (p = 0.05) in one site.Conclusions: Overall our attempt to improve CPR-quality was unsuccessful. Quality improvement likely requires a full range of implementation strategies to change current attitudes andpractices.

Quality of out-of-hospital cardiopulmonary resuscitation with real time automated feedback: A prospective interventional study

To compare quality of CPR during out-of-hospital cardiac arrest with and without automated feedback. Consecutive adult, out-of-hospital cardiac arrests of all causes were studied. One hundred and seventy-six episodes (March 2002-October 2003) without feedback were compared to 108 episodes (October 2003-September 2004) where automatic feedback on CPR was given. Automated verbal and visual feedback was based on measured quality with a prototype defibrillator. Quality of CPR was the main outcome measure and survival was reported as specified in the protocol. Average compression depth increased from (mean +/- S.D.) 34 +/- 9 to 38 +/- 6 mm (mean difference (95% CI) 4 (2, 6), P < 0.001), and median percentage of compressions with adequate depth (38-51 mm) increased from 24% to 53% (P < 0.001, Mann-Whitney U-test) with feedback. Mean compression rate decreased from 121 +/- 18 to 109 +/- 12 min(-1) (difference -12 (-16, -9), P = 0.001). There were no changes in the mean number of ventilations per minute; 11 +/- 5 min(-1) versus 11 +/- 4 min(-1) (difference 0 (-1, 1), P = 0.8) or the fraction of time without chest compressions; 0.48 +/- 0.18 versus 0.45 +/- 0.17 (difference -0.03 (-0.08, 0.01), P = 0.08). With intention to treat analysis 7/241 control patients were discharged alive (2.9%) versus 5/117 with feedback (4.3%) (OR 1.5 (95% CI; 0.8, 3), P = 0.2). In a logistic regression analysis of all cases, witnessed arrest (OR 4.2 (95% CI; 1.6, 11), P = 0.004) and average compression depth (per mm increase) (OR 1.05 (95% CI; 1.01, 1.09), P = 0.02) were associated with rate of hospital admission. Automatic feedback improved CPR quality in this prospective non-randomised study of out-of-hospital cardiac arrest. Increased compression depth was associated with increased short-term survival. ClinicalTrials.gov (NCT00138996), http://www.clinicaltrials.gov/.

A Randomized, Controlled Comparison of Cardiopulmonary Resuscitation Performed on the Floor andon a Moving Ambulance Stretcher

Background. Recent studies have demonstrated that cardiopulmonary resuscitation (CPR) of poor quality is associated with worsened outcomes. Objective. To compare the quality of CPR delivered on the floor with the quality of CPR delivered on a moving stretcher. The authors hypothesized that CPR performed on the floor would be superior to that performed on a moving stretcher. Methods. A randomized, crossover experimental design was used. Subjects included emergency medical technician students, paramedic students, andemergency medicine residents. Two-member teams were randomly assigned to perform two-rescuer CPR on a manikin either on the floor or on a moving stretcher. After a 5-minute rest, the teams performed CPR under the opposite condition. Compression andventilation data were collected using a recording resuscitation manikin. Dependent variables were compression depth, compression rate per minute, percentage of correct chest compressions, tidal volume, andpercentage of correct ventilations. Data were compared using two-tailed paired t-test. Results. Sixty-two subjects completed the study. The mean compression depth performed on the floor (39 ± 9 mm) was greater than that on a moving stretcher (28 ± 9 mm) (p < 0.001). The mean rates of chest compressions on the floor (110 ± 17 beats/min) andon a moving stretcher (113 ± 21 beats/min) were not different (p = 0.49). The percentage of correct compressions performed on the floor (54% ± 40%) exceeded that on a moving stretcher (21% ± 29%)(p < 0.001). The percentage of correct ventilations performed on the floor (43% ± 26%) was greater than that on a moving stretcher (24% ± 21%)(p < 0.04). Conclusions. Chest compression andventilation quality of CPR performed on the floor was superior to that of CPR performed on a moving stretcher in this manikin model. The quality of CPR while moving was significantly compromised.

CPREzy™: an evaluation during simulated cardiac arrest on a hospital bed

CPREzy is a new adjunct designed to improve the application of manual external chest compressions (ECC) during cardiopulmonary resuscitation (CPR). The aim of this study was to determine the effect of using the CPREzy device compared to standard CPR during the simulated resuscitation of a patient on a hospital bed. Twenty medical student volunteers were randomised using a cross over trial design to perform 3 min of continuous ECC using CPREzy and standard CPR. There was a significant improvement in ECC depth with CPREzy compared to standard CPR 42.9 (4.4) mm versus 34.2 (7.6): mm, P = 0.001; 95% CI d.f. 4.4-12.9 mm. This translated to a reduction in the percentage of shallow compressions (<38 mm) with CPREzy 16 (23)% compared to standard CPR 59 (44)%, P = 0.003. There was a small increase in the percentage of compression regarded excessive (>51 mm): CPREzy 6.5 (19)% versus standard CPR 0 (0.1)%. P = 0.012). There was no difference in compression rate or duty cycle between techniques. Equal numbers of participants (40% in each group) performed one of more incorrectly placed chest compression. However the total number of incorrect compressions was higher for the CPREzy group (26% versus 3.9% standard CPR, P < 0.001). This was due to a higher number of low compressions (26% of total compressions for CPREzy versus 1% for standard CPR, P < 0.001). In conclusion, CPREzy was associated with significant improvements in ECC performance. Further animal and clinical studies are required to validate this finding in vivo and to see if it translates to an improvement in outcome in human victims of cardiac arrest.

Uninterrupted chest compression CPR is easier to perform and remember than standard CPR

It has long been observed that CPR skills rapidly decline regardless of the modality used for teaching or criteria used for testing. Uninterrupted chest compression CPR (UCC-CPR) is a proposed alternative to standard single rescuer CPR (STD-CPR) for laypersons in witnessed unexpected cardiac arrest in adults. It delivers substantially more compressions per minute and may be easier to remember and perform than standard CPR. In this prospective study, 28 medical students were taught STD-CPR and UCC-CPR and then were tested on each method at baseline (0), 6, and 18 months after training. The students' performance for at least 90 s of CPR was evaluated based on video and Laerdal Skillreporter Resusci Anne recordings. The mean number of correct chest compressions delivered per minute trended down over time in STD-CPR (23 +/- 3, 19 +/- 4 , and 15 +/- 3; P = 0.09) but stayed the same in UCC-CPR (43 +/- 9, 38 +/- 7, and 37 +/- 7 = 0.91) at 0, 6, and 18 months, respectively. The mean percentage of chest compressions delivered correctly fell over time in STD-CPR (54 +/- 6%, 35 +/- 6%, and 32 +/- 6%; P = 0.02) but stayed the same in UCC-CPR (34 +/- 5%, 41 +/- 7%, and 38 +/- 8%) at 0, 6, and 18 months, respectively. The number of chest compressions delivered per minute was higher in UCC-CPR at 0, 6, and 18 months (113 versus 44, P < 0.0001; 94 versus 47, P < 0.0001; and 92 versus 44, P < 0.001). The greater number of chest compressions was due to a mean ventilaroty pause of 13-14 s during STD-CPR at all three time points. Chest compression performance during STD-CPR declined in repeated testing over 18 months whereas there was minimal decline in chest compressions performance on repeated testing of UCC-CPR. In addition, substantially more chest compressions were delivered during UCC-CPR compared to STD-CPR at all time points primarily because of long pauses accompanying rescue breathing.

Cardiopulmonary resuscitation training for students of odontology: skills acquisition after two periods of learning

Introduction: Although life threatening emergencies in dental practice are not frequent, dentists have to be competent in providing basic life support (BLS). Objectives: The aim of this work was to study the level of skills acquisition among dentistry students in two different periods of one rescuer-BLS training, a first short practice training of 2 h followed by 8 h of practice over a period of 2 months. Methods: One hundred and sixteen second-year undergraduate students of Anesthesiology at the Dental School of the Complutense University in Madrid were tested at the end of the two periods of learning using a recording manikin with a validated scoring system (Laerdal Resusci-Anne). This manikin recorded the percentage of adequate chest compressions and insuflations, rate of chest compressions and the causes of error in each case. Results: Final global results were, 51.66±3.0% adequate chest compressions; and 54.44±3.61% adequate insuflations. The kinds of errors where different in both tests were, wrong hand position (26.92±2.96 vs. 12.29±2.40%, P<0.001); excessive compressions (27.71±2.90 vs. 16.02±2.33%, P<0.05); and weak compressions (23.28±3.24 vs. 16.77±2.57%, P<0.05). Regression analysis found a positive correlation among excessive compression, height and weight ( P<0.001) and a negative correlation between weak compression, height and weight ( P<0.001). Conclusions: The poor overall results, although similar to those shown in the literature, have made us question the validity of our methods of teaching BLS. We were able to establish a correlation between demographic and sociocultural variables with the typical errors, and to begin the process of improving our teaching methods.

An analysis of the efficacy of bag-valve-mask ventilation and chest compression during different compression–ventilation ratios in manikin-simulated paediatric resuscitation

The ideal chest compression and ventilation ratio for children during performance of cardiopulmonary resuscitation (CPR) has not been determined. The efficacy of chest compression and ventilation during compression–ventilation ratios of 5:1, 10:2 and 15:2 was examined. Eighteen nurses, working in pairs, were instructed to provide chest compression and bag-valve-mask ventilation for 1 min with each ratio in random on a child-sized manikin. The subjects had been previously taught paediatric CPR within the last 3 or 5 months. The efficacy of ventilation was assessed by measurement of the expired tidal volume and the number of breaths provided. The rate of chest compression was guided by a metronome set at 100/min. The efficacy of chest compressions was assessed by measurement of the rate and depth of compression. There was no significant difference in the mean tidal volume or the percentage of effective chest compressions delivered for each compression–ventilation ratio. The number of breaths delivered was greatest with the ratio of 5:1. The percentage of effective chest compressions was equal with all three methods but the number of effective chest compressions was greatest with a ratio of 5:1. This study supports the use of a compression–ventilation ratio of 5:1 during two-rescuer paediatric cardiopulmonary resuscitation.

The Importance of Physical Fitness In the Performance of Adequate Cardiopulmonary Resuscitation

The aim of the present investigation was to evaluate the influence of the physical fitness of a cardiopulmonary resuscitation (CPR) provider on the performance of and physiologic response to CPR. To this end, comparisons were made of sedentary and physically active subjects in terms of CPR performance and physiologic variables. Two study groups were established: group P (n=14), composed of sedentary, professional CPR rescuers (mean [+/-SD]; age, 34+/-6 years; VO2max, 32.5+/-5.5 mL/kg/min), and group Ex (n=14), composed of physically active, nonexperienced subjects (age, 34+/-6 years; VO2max, 44.5+/-8.5 mL/kg/min). Each subject was required to perform an 18-min CPR session, which involved manual external cardiac compressions (ECCs) on an electronic teaching mannequin following accepted standard CPR guidelines. Subjects' gas exchange parameters and heart rates (HRs) were monitored throughout the trial. Variables indicating the adequacy of the ECCs (ECC depth and the percentage of incorrect compressions and hand placements) also were determined. Overall CPR performance was similar in both groups. The indicators of ECC adequacy fell within accepted limits (ie, an ECC depth between 38 and 51 mm). However, fatigue prevented four subjects from group P from completing the trial. In contrast, the physiologic responses to CPR differed between groups. The indicators of the intensity of effort during the trial, such as HR or percentage of maximum oxygen uptake (VO2max) were higher in group P subjects than group Ex subjects, respectively (HRs at the end of the trial, 139+/-22 vs 115+/-17 beats/min, p < 0.01; percentage of VO2max after 12 min of CPR, 46.7+/-9.7% vs 37.2+/-10.4%, p < 0.05). These results suggest that a certain level of physical fitness may be beneficial to CPR providers to ensure the adequacy of chest compressions performed during relatively long periods of cardiac arrest.

The effect of rescuer fatigue on the quality of chest compressions

Objective: The aim of this study was to evaluate the influence of rescuer fatigue on the quality of chest compressions and the influence of the rescuer's gender, age, weight, height or professional status on the reduction of quality of chest compressions caused by fatigue. Material and methods: The study was carried out with the Laerdal Skillmeter™ Resusci Anne® manikin. The participants were doctors and nurses who work in the Intensive Care and Emergency departments, with an age ranging from 25 to 45 years and trained in cardiopulmonary resuscitation (CPR). Statistical analysis of results includes analysis variance and three models of multiple linear regression. Results: Thirty-eight people took part in the experiment; 20 (52.6%) were females; 15 (39.5%) staff physicians, 15 (39.5%) nurses and eight residents. Mean age was 34.1 years (SD=4.1). We found a significant reduction in correct compression performance over the course of time: in the first minute 79.7%, in the second 24.9%, in the third 18%, in the fourth 17.7% and in the last minute 18.5%. There were no differences related to the rescuer's gender or profession. The median interval until rescuers appreciated the effect of the fatigue on chest compressions quality was 186 s (SD=84.1); that appreciation was not influenced by gender, age, weight, height or profession. There were no differences in the percentage of correct compressions related to gender ( P=0.07), insufficient sternal depression ( P=0.23) or total number of compressions in the first minute. Discussion: A decrease of compressions quality after the first minute of CPR is produced. This effect does not depend on gender, age, weight, height or rescuer's profession and it is not adequately perceived by the person who performs the chest compressions.

A randomized, controlled trial of the efficacy of closed chest compressions in ambulances

Objective. To examine the feasibility of closed chest compressions in ambulances.Methods. Ten male emergency medical technicians performed closed chest compressions on a Laerdal Skillmeter Resusci Anne placed 1) on the ground, 2) on the stretcher of an MB 510 ALS ambulance, 3) on the stretcher of an MB 310 ambulance, and 4) on the stretcher of a VW T4 BLS ambulance for 2 minutes each. The authors noted the percentage of correct compressions as shown by the mannequin and counted the heart rate of the participants before and after each session. The authors compared the percentage of correct compressions and the increase in heart rate during the three ambulance sessions with those of the session on the ground by rank order test for paired observations. A p < 0.05 after Bonferroni correction (factor 3) was considered significant.Results. The percentage of correct compressions was 90% ± 7% on the ground, 77% ± 19% in the MB 510,60% ± 31% in the MB 310, and 38% ± 24% in the VW T4. Heart rate increase was 18 ± 16 min−1 on the ground, 23 ± 9 min-1 in the MB 510,30 ± 16 min-1 in the MB 310, and 32 ± 13 min-1 in the VW T4. Only the difference in percentage of correct compressions between on the ground and the VW T4 was significant (p < 0.01 after Bonferroni correction).Conclusions. The percentage of correct compressions in all the vehicles tested was lower when compared with the percentage on the ground, and the increase in heart rate was higher. Only one of these results was statistically significant. A further study with more participants seems warranted.

Decay in Quality of Closed-Chest Compressions Over Time

Study objective: To characterize fatigue-induced deterioration in the adequacy of closed-chest compressions performed over a period of 5 minutes and to determine whether CPR providers can recognize the effects of fatigue on compression adequacy. Design: Prospective evaluation of study subjects performing closed-chest compressions on an electronic mannequin that assesses compression placement and depth. Setting: Major resuscitation room in rural university hospital emergency department. Participants: Eleven experienced nursing assistants who regularly provide CPR in the ED. Results: Each study participant performed 5 minutes of closed-chest compressions. Compression adequacy (for placement and depth) was assessed with the mannequin and reported on an attached monitor out of view of the study subjects. Subjects were asked to verbally indicate the point during their 5-minute compression period at which they felt too fatigued to provide effective compressions (arbitrarily defined as a minimum of 90% of all compressions being judged correct by the mannequin). We used one-way repeated-measures ANOVA and regression analysis to determine whether compression adequacy diminished over time. ANOVA was also used to determine whether the total compressions performed per minute diminished over time. The percentage of correct chest compressions decreased significantly after 1 minute of compressions (P =.0001). We found 92.9% of compressions performed during minute 1 to be correct. The percentages for minutes 2 through 5 were as follows: 67.1%, 39.2%, 31.2%, and 18.0%. Regression analysis revealed a decrement in compression adequacy of 18.6% per minute after the first minute of compressions. The number of total compressions attempted per minute did not decrease (P =.98). Study subjects did not accurately identify the point during their 5-minute sessions at which their fatigue caused compressions to become impaired. Whereas mean compression adequacy declined below 90% after only 1 minute, the time of indicated fatigue was 253±40 seconds (mean±SD). Conclusion: Although compression rate was maintained over time, chest compression quality declined significantly over the study period. Because CPR providers could not recognize their inability to provide proper compressions, cardiac arrest team leaders should carefully monitor compression adequacy during CPR to assure maximally effective care for patients receiving CPR. [Hightower D, Thomas SH, Stone CK, Dunn K, March JA: Decay in quality of closed-chest compressions over time. Ann Emerg Med September 1995;26:300-303.]

Can correct closed-chest compressions be performed during prehospital transport?

The resuscitation rate from out-of-hospital cardiac arrest is low. There are many factors to be considered as contributing to this phenomenon. One factor not previously considered is the impact of a moving ambulance environment on the ability to perform closed-chest compressions. Proper closed-chest compressions can be performed in a moving ambulance. A cardiopulmonary resuscitation (CPR) training mannequin with an attached skill meter (Skillmeter ResusciAnnie, Laerdal, Armonk, N.Y., USA) that measures each chest compression for proper depth and hand placement was used. Ten emergency medical technician-basic (EMT-B) certified prehospital providers were assigned into one of five teams. Each team performed a total of four sessions of five minutes of continuous closed-chest compressions on the mannequin. Two sessions were done by each team: one in the control environment with the mannequin placed on the floor, and the other in the experimental environment with the mannequin placed in the back of a moving ambulance. The ambulance was operated without warning lights and siren, and all traffic rules were obeyed. The percentage of correct closed-chest compressions was recorded for each session, and the mean values were compared using Student's t-test with alpha set at 0.01 for statistical significance. Ten sessions of compressions were done in both environments. The mean percentage of correct compressions was 77.6 +/- 15.6 for the control group and 45.6 +/- 18.3 for the ambulance group (p = 0.0005). A moving ambulance environment appears to impair the ability to perform closed-chest compressions.