Hemodynamic directed CPR improves short-term survival from asphyxia-associated cardiac arrest

Aim

Adequate coronary perfusion pressure (CPP) during cardiopulmonary resuscitation (CPR) is essential for establishing return of spontaneous circulation. The objective of this study was to compare short-term survival using a hemodynamic directed resuscitation strategy versus an absolute depth-guided approach in a porcine model of asphyxia-associated cardiac arrest. We hypothesized that a hemodynamic directed approach would improve short-term survival compared to depth-guided care.

Methods

After 7 min of asphyxia, followed by induction of ventricular fibrillation, 19 female 3-month old swine (31 ± 0.4 kg) were randomized to receive one of three resuscitation strategies: (1) hemodynamic directed care (CPP-20): chest compressions (CCs) with depth titrated to a target systolic blood pressure of 100 mmHg and titration of vasopressors to maintain CPP > 20 mmHg; (2) depth 33 mm (D33): target CC depth of 33 mm with standard American Heart Association (AHA) epinephrine dosing; or (3) depth 51 mm (D51): target CC depth of 51 mm with standard AHA epinephrine dosing. All animals received manual CPR guided by audiovisual feedback for 10 min before first shock.

Results

45-Min survival was higher in the CPP-20 group (6/6) compared to D33 (1/7) or D51 (1/6) groups; p = 0.002. Coronary perfusion pressures were higher in the CPP-20 group compared to D33 (p = 0.011) and D51 (p = 0.04), and in survivors compared to non-survivors (p < 0.01). Total number of vasopressor doses administered and defibrillation attempts were not different.

Conclusions

Hemodynamic directed care targeting CPPs > 20 mmHg improves short-term survival in an intensive care unit porcine model of asphyxia-associated cardiac arrest.     

Chest compression depth and survival in out-of-hospital cardiac arrest

Aim

Outcomes from out-of-hospital cardiac arrest (OHCA) may improve if rescuers perform chest compressions (CCs) deeper than the previous recommendation of 38–51 mm and consistent with the 2010 AHA Guideline recommendation of at least 51 mm. The aim of this study was to assess the relationship between CC depth and OHCA survival.

Methods

Prospective analysis of CC depth and outcomes in consecutive adult OHCA of presumed cardiac etiology from two EMS agencies participating in comprehensive CPR quality improvement initiatives. Analysis: Multivariable logistic regression to calculate adjusted odds ratios (aORs) for survival to hospital discharge and favorable functional outcome.

Results

Among 593 OHCAs, 136 patients (22.9%) achieved return of spontaneous circulation, 63 patients (10.6%) survived and 50 had favorable functional outcome (8.4%). Mean CC depth was 49.8 ± 11.0 mm and mean CC rate was 113.9 ± 18.1 CC min⁻¹. Mean depth was significantly deeper in survivors (53.6 mm, 95% CI: 50.5–56.7) than non-survivors (48.8 mm, 95% CI: 47.6–50.0). Each 5 mm increase in mean CC depth significantly increased the odds of survival and survival with favorable functional outcome: aORs were 1.29 (95% CI 1.00–1.65) and 1.30 (95% CI 1.00–1.70) respectively.

Conclusion

Deeper chest compressions were associated with improved survival and functional outcome following OHCA. Our results suggest that adhering to the 2010 AHA Guideline-recommended depth of at least 51 mm could improve outcomes for victims of OHCA.     

Hemodynamic directed CPR improves cerebral perfusion pressure and brain tissue oxygenation

Aim

Advances in cardiopulmonary resuscitation (CPR) have focused on the generation and maintenance of adequate myocardial blood flow to optimize the return of spontaneous circulation and survival. Much of the morbidity associated with cardiac arrest survivors can be attributed to global brain hypoxic ischemic injury. The objective of this study was to compare cerebral physiological variables using a hemodynamic directed resuscitation strategy versus an absolute depth-guided approach in a porcine model of ventricular fibrillation (VF) cardiac arrest.

Methods

Intracranial pressure and brain tissue oxygen tension probes were placed in the frontal cortex prior to induction of VF in 21 female 3-month-old swine. After 7 min of VF, animals were randomized to receive one of three resuscitation strategies: (1) hemodynamic directed care (CPP-20): chest compressions (CCs) with depth titrated to a target systolic blood pressure of 100 mmHg and titration of vasopressors to maintain coronary perfusion pressure (CPP) >20 mmHg; (2) depth 33 mm (D33): target CC depth of 33 mm with standard American Heart Association (AHA) epinephrine dosing; or (3) depth 51 mm (D51): target CC depth of 51 mm with standard AHA epinephrine dosing.

Results

Cerebral perfusion pressures (CerePP) were significantly higher in the CPP-20 group compared to both D33 (p < 0.01) and D51 (p = 0.046), and higher in survivors compared to non-survivors irrespective of treatment group (p < 0.01). Brain tissue oxygen tension was also higher in the CPP-20 group compared to both D33 (p < 0.01) and D51 (p = 0.013), and higher in survivors compared to non-survivors irrespective of treatment group (p < 0.01). Subjects with a CPP >20 mmHg were 2.7 times more likely to have a CerePP >30 mmHg (p < 0.001).

Conclusions

Hemodynamic directed resuscitation strategy targeting coronary perfusion pressure >20 mmHg following VF arrest was associated with higher cerebral perfusion pressures and brain tissue oxygen tensions during CPR.     

First quantitative analysis of cardiopulmonary resuscitation quality during in-hospital cardiac arrests of young children

Aim

The objective of this study is to report, for the first time, quantitative data on CPR quality during the resuscitation of children under 8 years of age. We hypothesized that the CPR performed would often not achieve 2010 Pediatric Basic Life Support (BLS) Guidelines, but would improve with the addition of audiovisual feedback.

Methods

Prospective observational cohort evaluating CPR quality during chest compression (CC) events in children between 1 and 8 years of age. CPR recording defibrillators collected CPR data (rate (CC/min), depth (mm), CC fraction (CCF), leaning (%> 2.5 kg.)). Audiovisual feedback was according to 2010 Guidelines in a subset of patients. The primary outcome, “excellent CPR” was defined as a CC rate ≥100 and ≤120 CC/min, depth ≥50 mm, CCF >0.80, and <20% of CC with leaning.

Results

8 CC events resulted in 285 thirty-second epochs of CPR (15,960 CCs). Percentage of epochs achieving targets was 54% (153/285) for rate, 19% (54/285) for depth, 88% (250/285) for CCF, 79% (226/285) for leaning, and 8% (24/285) for excellent CPR. The median percentage of epochs per event achieving targets increased with audiovisual feedback for rate [88 (IQR: 79, 94) vs. 39 (IQR 18, 62) %; p = 0.043] and excellent CPR [28 (IQR: 7.2, 52) vs. 0 (IQR: 0, 1) %; p = 0.018].

Conclusions

In-hospital pediatric CPR often does not meet 2010 Pediatric BLS Guidelines, but compliance is better when audiovisual feedback is provided to rescuers.     

Pushing harder,pushing faster,minimizing interruptions… But falling short of 2010 cardiopulmonary resuscitation targets during in-hospital pediatric and adolescent resuscitation

Aim

The objective of this study was to evaluate the effect of instituting the 2010 Basic Life Support Guidelines on in-hospital pediatric and adolescent cardiopulmonary resuscitation (CPR) quality. We hypothesized that quality would improve, but that targets for chest compression (CC) depth would be difficult to achieve.

Methods

Prospective in-hospital observational study comparing CPR quality 24 months before and after release of the 2010 Guidelines. CPR recording/feedback-enabled defibrillators collected CPR data (rate (CC/min), depth (mm), CC fraction (CCF, %), leaning (% > 2.5 kg)). Audiovisual feedback for depth was: 2005, ≥38 mm; 2010, ≥50 mm; for rate: 2005, ≥90 and ≤120 CC/min; 2010, ≥100 and ≤120 CC/min. The primary outcome was average event depth compared with Student's t-test.

Results

45 CPR events (25 before; 20 after) occurred, resulting in 1336 thirty-second epochs (909 before; 427 after). Compared to 2005, average event depth (50 ± 13 mm vs. 43 ± 9 mm; p = 0.047), rate (113 ± 11 CC/min vs. 104 ± 8 CC/min; p < 0.01), and CCF (0.94 [0.93, 0.96] vs. 0.9 [0.85, 0.94]; p = 0.013) increased during 2010. CPR epochs during the 2010 period more likely to meet Guidelines for CCF (OR 1.7; CI95: 1.2–2.4; p < 0.01), but less likely for rate (OR 0.23; CI95: 0.12–0.44; p < 0.01), and depth (OR 0.31; CI95: 0.12–0.86; p = 0.024).

Conclusions

Institution of the 2010 Guidelines was associated with increased CC depth, rate, and CC fraction; yet, achieving 2010 targets for rate and depth was difficult.     

American Heart Association cardiopulmonary resuscitation quality targets are associated with improved arterial blood pressure during pediatric cardiac arrest

Aim

To evaluate the association between cardiopulmonary resuscitation (CPR) quality and hemodynamic measurements during in-hospital pediatric cardiac arrest. We hypothesized that AHA recommended CPR rate and depth targets would be associated with systolic blood pressures ≥ 80 mmHg and diastolic blood pressures ≥ 30 mmHg.

Methods

In children and adolescents <18 years of age who suffered a cardiac arrest with an invasive arterial catheter in place, a CPR monitoring defibrillator collected CPR data which was synchronized to arterial blood pressure (BP) tracings. Chest compression (CC) depths were corrected for mattress deflection. Generalized least squares regression estimated the association between BP and CPR quality, treated as continuous variables. Mixed-effects logistic regression estimated the association between systolic BP ≥ 80 mmHg/diastolic BP ≥ 30 mmHg and the AHA targets of depth ≥ 38 mm and/or rate ≥ 100/min.

Results

Nine arrests resulted in 4156 CCs. The median mattress corrected depth was 32 mm (IQR 28–38); median rate was 111 CC/min (IQR 103–120). AHA depth was achieved in 1090/4156 (26.2%) CCs; rate in 3441 (83.7%). Systolic BP ≥ 80 mmHg was attained in 2516/4156 (60.5%) compressions; diastolic ≥ 30 mmHg in 2561/4156 (61.6%). A rate ≥ 100/min was associated with systolic BP ≥ 80 mmHg (OR 1.32; CI⁹⁵ 1.04, 1.66; p = 0.02) and diastolic BP ≥ 30 mmHg (OR 2.15; CI⁹⁵ 1.65, 2.80; p < 0.001). Exceeding both (rate ≥ 100/min and depth ≥ 38 mm) was associated with systolic BP ≥ 80 mmHg (OR 2.02; CI⁹⁵ 1.45, 2.82; p < 0.001) and diastolic BP ≥ 30 mmHg (OR 1.48; CI⁹⁵ 1.01, 2.15; p = 0.042).

Conclusions

AHA quality targets (rate ≥ 100/min and depth ≥ 38 mm) were associated with systolic BPs ≥ 80 mmHg and diastolic BPs ≥ 30 mmHg during CPR in children.     

Effect of mattress and bed frame deflection on real chest compression depth measured with two CPR sensors

Aim

Implementation of chest compression (CC) feedback devices with a single force and deflection sensor (FDS) may improve the quality of CPR. However, CC depth may be overestimated if the patient is on a compliant surface. We have measured the true CC depth during in-hospital CPR using two FDSs on different bed and mattress types.

Methods

This prospective observational study was conducted at Tampere University Hospital between August 2011 and September 2012. During in-hospital CPR one FDS was placed between the rescuer's hand and the patient's chest, with the second attached to the backboard between the patient's back and the mattress. The real CC depth was calculated as the difference between the total depth from upper FDS to lower FDS.

Results

Ten cardiac arrests on three different bed and mattress types yielded 10,868 CCs for data analyses. The mean (SD) mattress/bed frame effect was 12.8 (4) mm on a standard hospital bed with a gel mattress, 12.4 (4) mm on an emergency room stretcher with a thin gel mattress and 14.1 (3) mm on an ICU bed with an emptied air mattress. The proportion of CCs with an adequate depth (≥50 mm) decreased on all mattress types after compensating for the mattress/bed frame effect from 94 to 64%, 98 to 76% and 91 to 17%, in standard hospital bed, emergency room stretcher and ICU bed, respectively (p < 0.001).

Conclusion

The use of FDS without real-time correction for deflection may result in CC depth not reaching the recommended depth of 50 mm.     

A modeling approach to the effects of force guided versus depth guided compression during cardiopulmonary resuscitation on different chests and back support surfaces

Objectives

To validate an existing theoretical model for the mechanics of chest compression (CC) during constant peak force cardiopulmonary resuscitation (CPR) using experimental human and manikin CC data from the literature. Also, to gain insights into the clinical application of force guided CPR.

Methods

The experimental CC data from the literature were analyzed and compared to theoretical predictions from the constant peak force CPR model. The CPR model was also used to explore how CC rate and peak sternal force may influence CC performance during the clinical application of force guided CPR.

Results

The model predictions matched the human CC data to within an average difference of less than 1.5% at CC rates of 60 cpm and 90 cpm, and 0.6% for the manikin data at a CC rate of 90 cpm. The model predictions also showed that the net sternum-to-spine compression depth achieved during force guided CPR strongly depends on the patient's thoracic stiffness.

Conclusions

Good quantitative agreement between the experimental data from the literature and the theoretical model suggests that the constant peak force CPR model developed by Boe and Babbs provides reasonable prediction of CC mechanics during CPR over a range of clinically relevant CC rates. The model predictions also suggest that the effectiveness of CC during force guided CPR is highly sensitive to the patient's thoracic stiffness and insensitive to the back support stiffness. Patients having high thoracic stiffness (≥100 N cm⁻¹) were found to require higher CC forces, which may exceed the force above which severe chest wall trauma and abdominal injury occurs, in order to achieve the ERC recommended CC depth range. This suggests that the choice of maximum sternal force applied by clinicians during constant peak force CPR ought to be based on a general assessment of the patient's thoracic stiffness.     

3:1 Compression to ventilation ratio versus continuous chest compression with asynchronous ventilation in a porcine model of neonatal resuscitation

Objective

In contrast to the resuscitation guidelines of children and adults, guidelines on neonatal resuscitation recommend synchronized 90 chest compressions with 30 manual inflations (3:1) per minute in newborn infants. The study aimed to determine if chest compression with asynchronous ventilation improves the recovery of bradycardic asphyxiated newborn piglets compared to 3:1 Compression:Ventilation cardiopulmonary resuscitation (CPR).

Intervention and measurements

Term newborn piglets (n = 8/group) were anesthetized, intubated, instrumented and exposed to 45-min normocapnic hypoxia followed by asphyxia. Protocolized resuscitation was initiated when heart rate decreased to 25% of baseline. Piglets were randomized to receive resuscitation with either 3:1 compressions to ventilations (3:1 C:V CPR group) or chest compressions with asynchronous ventilations (CCaV) or sham. Continuous respiratory parameters (Respironics NM3^®), cardiac output, mean systemic and pulmonary artery pressures, and regional blood flows were measured.

Main results

Piglets in 3:1 C:V CPR and CCaV CPR groups had similar time to return of spontaneous circulation, survival rates, hemodynamic and respiratory parameters during CPR. The systemic and regional hemodynamic recovery in the subsequent 4 h was similar in both groups and significantly lower compared to sham-operated piglets.

Conclusion

Newborn piglets resuscitated by CCaV had similar return of spontaneous circulation, survival, and hemodynamic recovery compared to those piglets resuscitated by 3:1 Compression:Ventilation ratio.     

Chest compression depth after change in CPR guidelines—Improved but not sufficient

Aims

Cardiopulmonary resuscitation is one of the most vital therapeutic options for patients with cardiac arrest. Sufficient chest compression depth turned out to be of utmost importance to increase the likelihood of a return of spontaneous circulation. Furthermore, the use of real-time feedback-systems for resuscitation is associated with improvement of compression quality. The European Resuscitation Council changed their recommendation about minimal compression depth from 2005 (40 mm) to 2010 (50 mm). The aim of the present study was to determine whether this recommendation of the new guidelines was implemented successfully in an emergency medical service using a real-time feedback-system and to what extend a guideline-based CPR training leads to a “change in behaviour” of rescuers, respectively.

Methods and results

The electronic resuscitation data of 294 patients were analyzed retrospectively within two observational periods regarding fulfilment of the corresponding chest compression guideline requirements: ERC 2005 (40 mm) 01.07.2009–30.06.2010 (n = 145) and ERC 2010 (50 mm) 01.07.2011–30.06.2012 (n = 149). The mean compression depth during the first period was 47.1 mm (SD 11.1) versus 49.6 mm (SD 12.0) within the second period (p < 0.001). With respect to the corresponding ERC Guidelines 2005 and 2010, the proportion of chest compressions reaching the minimal depth decreased (73.9% vs. 49.1%) (p < 0.001). There was no correlation between compression depth and patient age, sex or duration of resuscitation.

Conclusions

The present study was able to show a significant increase in chest compression depth after implementation of the new ERC guidelines. Even by using a real-time feedback system we failed to sustain chest compression quality at the new level as set by ERC Guidelines 2010. In consequence, the usefulness of a fixed chest compression depth should be content of further investigations.     

Ability of code leaders to recall CPR quality errors during the resuscitation of older children and adolescents

Aim

Performance of high quality CPR is associated with improved resuscitation outcomes. This study investigates code leader ability to recall CPR error during post-event interviews when CPR recording/audiovisual feedback-enabled defibrillators are deployed.

Patients and methods

Physician code leaders were interviewed within 24 h of 44 in-hospital pediatric cardiac arrests to assess their ability to recall if CPR error occurred during the event. Actual CPR quality was assessed using quantitative recording/feedback-enabled defibrillators. CPR error was defined as an overall average event chest compression (CC) rate <95/min, depth <38 mm, ventilation rate >10/min, or any interruptions in CPR >10 s. We hypothesized that code leaders would recall error when it actually occurred ≥75% of the time when assisted by audiovisual alerts from a CPR recording feedback-enabled defibrillators (analysis by χ²).

Results

810 min from 44 cardiac arrest events yielded 40 complete data sets (actual and interview); ventilation data was available in 24. Actual CPR error was present in 3/40 events for rate, 4/40 for depth, 32/40 for interruptions >10 s, and 17/24 for ventilation frequency. In post-event interviews, code leaders recalled these errors in 0/3 (0%) for rate, 0/4 (0%) for depth, and 19/32 (59%) for interruptions >10 s. Code leaders recalled these CPR quality errors less than 75% of the time for rate (p = 0.06), for depth (p < 0.01), and for CPR interruption (p = 0.04). Quantification of errors not recalled: missed rate error median = 94 CC/min (IQR 93–95), missed depth error median = 36 mm (IQR 35.5–36.5), missed CPR interruption >10 s median = 18 s (IQR 14.4–28.9). Code leaders did recall the presence of excessive ventilation in 16/17 (94%) of events (p = 0.07).

Conclusion

Despite assistance by CPR recording/feedback-enabled defibrillators, pediatric code leaders fail to recall important CPR quality errors for CC rate, depth, and interruptions during post-cardiac arrest interviews.     

CPR variability during ground ambulance transport of patients in cardiac arrest

Aim of study

High-quality CPR is associated with improved outcomes from out-of-hospital cardiac arrest (OHCA). The purpose of this investigation was to compare the quality of CPR provided at the prehospital scene, during ambulance transport, and during the early minutes in the emergency department (ED).

Methods

A prospective observational review of consecutive adult patients with non-traumatic OHCA was conducted between September 2008 and February 2010. Patients with initiation of prehospital CPR were included as part of a statewide cardiac resuscitation quality improvement program. A monitor-defibrillator with accelerometer-based CPR measurement capability (E-series, ZOLL Medical) was utilized. CPR quality measures included variability in chest compression (CC) depth and rate, mean depth and rate, and the CC fraction. Variability of CC was defined as the mean of minute-to-minute standard deviation in CC depth or rate. CC fraction was defined as the percent of time that CPR was being performed when appropriate throughout resuscitation.

Results

Fifty-seven adult patients with OHCA had electronic CPR data recorded at the scene, in the ambulance, and upon arrival in the ED. Across time periods, there was increased variability in CC depth (scene: 0.20 in.; transport: 0.26 in.; ED: 0.31 in., P < 0.01) and rate (scene: 18.2 CC min⁻¹; transport: 26.1 CC min⁻¹; ED: 26.3 CC min⁻¹, P < 0.01). The mean CC depth, rate, and the CC fraction did not differ significantly between groups.

Conclusions

There was increased CC variability from the prehospital scene to the ED though there was no difference in mean CC depth, rate, or in CC fraction. The clinical significance of CC variability remains to be determined.     

Quality of chest compressions during compression-only CPR: a comparative analysis following the 2005 and 2010 American Heart Association guidelines

Objective

The latest guidelines both increased the requirements of chest compression rate and depth during cardiopulmonary resuscitation (CPR), which may make it more difficult for the rescuer to provide high-quality chest compression. In this study, we investigated the quality of chest compressions during compression-only CPR under the latest 2010 American Heart Association (AHA) guidelines (AHA 2010) and its effect on rescuer fatigue.

Methods

Eighty-six undergraduate volunteers were randomly assigned to perform CPR according to the 2005 AHA guidelines (AHA 2005) or AHA 2010. After the training course and theoretical examination of basic life support, eight min of compression-only CPR performance was assessed. The quality of chest compressions including rate and depth of compression was analyzed. The rescuer fatigue was evaluated by the changes of heart rate and blood lactate, and rating of perceived exertion.

Results

Thirty-nine participants in the AHA 2005 group and 42 participants in the AHA 2010 group completed the study. Significantly greater mean chest compression depth and compression rate were both achieved in the AHA 2010 group than in the AHA 2005 group. And significantly greater rescuer fatigue was observed in the AHA 2010 group. In addition, the female in the AHA 2010 group could perform the compression rate required by the guidelines, however, significantly shallower compression depth and greater rescuer fatigue were observed when compared to the male.

Conclusions

The quality of chest compressions was significantly improved following the 2010 AHA guidelines, however, it’s more difficult for the rescuer to meet the guidelines due to the increased fatigue of rescuer.     

Audiovisual feedback device use by health care professionals during CPR: A systematic review and meta-analysis of randomised and non-randomised trials

Objectives

A systematic appraisal of the literature to determine if audiovisual feedback devices can improve CPR quality delivered by health care practitioners (HCPs) and/or survival outcomes following cardiac arrest.

Methods

We searched the Cochrane Central Register of Controlled Studies (CENTRAL) on The Cochrane Library, MEDLINE, EMBASE, CIHAHL and AUSTHEALTH in May 2013 for experimental and observational (human or manikin) studies examining the effect of the use of audiovisual feedback devices by HCPs in simulated and actual cardiac arrest. The primary outcome for human studies was survival to hospital discharge with good neurologic outcome. Secondary outcomes were other survival data and quality of CPR performance; the latter was also reported for manikin studies.

Results

Three human interventional studies (n = 2100) and 17 manikin studies met the inclusion criteria. Overall quality of included studies was poor, with significant clinical heterogeneity. All three human studies reported no significant change to any survival outcomes despite improvement in chest compression (CC) depth by 2.5 mm (95% CI 0.9–4.3), CC rate 6 min⁻¹ closer to 100 (95% CI 2.4–10.7) and a reduction in no-flow fraction by 1.9% on meta-analysis. Manikin studies showed similar improvements in CC parameters.

Conclusion

In both manikin and human studies, feedback during resuscitation can result in rescuers providing CC parameters closer to recommendations. There is no evidence that this translates into improved patient outcomes. The reason for this is not yet evident and further patient centered research is warranted.     

Excessive chest compression rate is associated with insufficient compression depth in prehospital cardiac arrest

Background and goal of study

The relationship between chest compression rate and compression depth is unknown. In order to characterise this relationship, we performed an observational study in prehospital cardiac arrest patients. We hypothesised that faster compressions are associated with decreased depth.

Materials and methods

In patients undergoing prehospital cardiopulmonary resuscitation by health care professionals, chest compression rate and depth were recorded using an accelerometer (E-series monitor-defibrillator, Zoll, USA). Compression depth was compared for rates <80/min, 80–120/min and >120/min. A difference in compression depth ≥0.5 cm was considered clinically significant. Mixed models with repeated measurements of chest compression depth and rate (level 1) nested within patients (level 2) were used with compression rate as a continuous and as a categorical predictor of depth. Results are reported as means and standard error (SE).

Results and discussion

One hundred and thirty-three consecutive patients were analysed (213,409 compressions). Of all compressions 2% were <80/min, 62% between 80 and 120/min and 36% >120/min, 36% were <4 cm deep, 45% between 4 and 5 cm, 19% >5 cm. In 77 out of 133 (58%) patients a statistically significant lower depth was observed for rates >120/min compared to rates 80–120/min, in 40 out of 133 (30%) this difference was also clinically significant. The mixed models predicted that the deepest compression (4.5 cm) occurred at a rate of 86/min, with progressively lower compression depths at higher rates. Rates >145/min would result in a depth <4 cm. Predicted compression depth for rates 80–120/min was on average 4.5 cm (SE 0.06) compared to 4.1 cm (SE 0.06) for compressions >120/min (mean difference 0.4 cm, P < 0.001). Age and sex of the patient had no additional effect on depth.

Conclusions

This study showed an association between higher compression rates and lower compression depths. Avoiding excessive compression rates may lead to more compressions of sufficient depth.     

Rescuer Fatigue in the Elderly: Standard vs. Hands-only CPR

Background

Hands-only cardiopulmonary resuscitation (HO-CPR) is recommended as an alternative to standard CPR (STD-CPR). Studies have shown a degradation of adequate compressions with HO-CPR after 2 min when performed by young, healthy medical students. Elderly rescuers' ability to maintain an adequate compression rate and depth until emergency medical services (EMS) arrives is unknown.

Objectives

The specific aim of this study was to compare elderly rescuers' ability to maintain adequate compression rate and depth during HO-CPR and STD-CPR in a manikin model.

Methods

In this prospective, randomized crossover study, 17 elderly volunteers performed both HO-CPR and STD-CPR, separated by at least 2 days, on a manikin model for 9 min each. The primary endpoint was the number of adequate chest compressions (> 38 mm) delivered per minute. Secondary endpoints were total compressions, compression rate, and the number of breaks taken for rest.

Results

There was no difference in the number of adequate compressions between groups in the first minute; however, the STD-CPR group delivered significantly more adequate chest compressions in minutes 2–9 (p < 0.05). The total number of compressions delivered was significantly greater in the HO-CPR than STD-CPR group when considering the entire resuscitation period. A significantly greater number of rescuers took breaks for rest during HO-CPR than STD-CPR.

Conclusions

Although HO-CPR resulted in a greater number of overall compressions than STD-CPR, STD-CPR resulted in a greater number of adequate compressions in all but the first minute of resuscitation.     

A novel method to decrease mattress compression during CPR using a mattress compression cover and a vacuum pump

Background

Mattress compression causes feedback devices to over-estimate the chest compression depth measurement during CPR. We propose a novel method to decrease the mattress compression using a vinyl cover. This mattress compression cover encloses the foam mattress and is compressed by a vacuum pump immediately prior to performing CPR.

Methods

Nine CPR providers performed chest compressions on manikins placed on a conventional foam mattress on a bed frame (surface CONV), a backboard and foam mattress on a bed frame (surface BB), and a foam mattress, compressed with a vacuum pump, on a bed frame (surface VAC). Dual accelerometers were used to simultaneously measure the mattress compression and chest compression depths.

Results

The mattress compression depth levels decreased from 14.9 mm (SD 1.4 mm) on surface CONV to 7.0 mm (SD 0.6 mm) on surface VAC (p < 0.001) whereas 14.0 mm (SD 1.3 mm) on surface BB. The total compression depth was 65.4 mm (SD 3.8 mm) on surface CONV, and 58.3 mm (SD 3.0 mm) on surface VAC (p < 0.001).

Conclusion

Using a mattress compression cover and a vacuum pump appears to increase the rigidity of the mattress and allow for efficient chest compressions. This novel method could decrease the mattress compression depth and increase the efficiency of chest compression during CPR in hospitals.     

A 10-s rest improves chest compression quality during hands-only cardiopulmonary resuscitation: A prospective,randomized crossover study using a manikin model

Objectives

This study was designed to assess changes in cardiopulmonary resuscitation (CPR) quality and rescuer fatigue when rescuers are provided with a break during continuous chest compression CPR (CCC-CPR).

Methods

The present prospective, randomized crossover study involved 63 emergency medical technician trainees. The subjects performed three different CCC-CPR methods on a manikin model. The first method was general CCC-CPR without a break (CCC), the second included a 10-s break after 200 chest compressions (10/200), and the third included a 10-s break after 100 chest compressions (10/100). All methods were performed for 10 min. We counted the total number of compressions and those with appropriate depth every 1 min during the 10 min and measured mean compression depth from the start of chest compressions to 10 min.

Results

The 10/100 method showed the deepest compression depth, followed by the 10/200 and CCC methods. The mean compression depth showed a significant difference after 5 min had elapsed. The percentage of adequate compressions per min was calculated as the proportion of compressions with appropriate depth among total chest compressions. The percentage of adequate compressions declined over time for all methods. The 10/100 method showed the highest percentage of adequate compressions, followed by the 10/200 and CCC methods.

Conclusion

When rescuers were provided a rest at a particular time during CCC-CPR, chest compression quality increased compared with CCC without rest. Therefore, we propose that a rescuer should be provided a rest during CCC-CPR, and specifically, we recommend a 10-s rest after 100 chest compressions.