Quality Comparison of the Manual Chest Compression and the Mechanical Chest Compression During Difficult Transport Conditions

Oxygenation and ventilation during prolonged experimental cardiopulmonary resuscitation with either continuous or 30:2 compression-to-ventilation ratios together with 10 cmH20 positive end-expiratory pressure

BACKGROUND

In refractory out-of-hospital cardiac arrest, the patient is commonly transported to hospital with mechanical continuous chest compressions (CCC). Limited data are available on the optimal ventilation strategy. Accordingly, we compared arterial oxygenation and haemodynamics during manual asynchronous continuous ventilation and compressions with a 30:2 compression-to-ventilation ratio together with the use of 10 cmH2O positive end-expiratory pressure (PEEP).

METHODS

Intubated and anaesthetized landrace pigs with electrically induced ventricular fibrillation were left untreated for 5 min (n = 31, weight ca. 55 kg), after which they were randomized to either the CCC group or the 30:2 group with the the LUCAS® 2 piston device and bag-valve ventilation with 100% oxygen targeting a tidal volume of 8 ml/kg with a PEEP of 10 cmH2O for 35 min. Arterial blood samples were analysed every 5 min, vital signs, near-infrared spectroscopy and electrical impedance tomography (EIT) were measured continuously, and post-mortem CT scans of the lungs were obtained.

RESULTS

The arterial blood values (median + interquartile range) at the 30-min time point were as follows: PaO2: 180 (86-302) mmHg for the 30:2 group; 70 (49-358) mmHg for the CCC group; PaCO2: 41 (29-53) mmHg for the 30:2 group; 44 (21-67) mmHg for the CCC group; and lactate: 12.8 (10.4-15.5) mmol/l for the 30:2 group; 14.7 (11.8-16.1) mmol/l for the CCC group. The differences were not statistically significant. In linear mixed models, there were no significant differences between the groups. The mean arterial pressures from the femoral artery, end-tidal CO2, distributions of ventilation from EIT and mean aeration of lung tissue in post-mortem CTs were similar between the groups. Eight pneumothoraces occurred in the CCC group and 2 in the 30:2 group, a statistically significant difference (p = 0.04).

CONCLUSIONS

The 30:2 and CCC protocols with a PEEP of 10 cmH2O resulted in similar gas exchange and vital sign outcomes in an experimental model of prolonged cardiac arrest with mechanical compressions, but the CCC protocol resulted in more post-mortem pneumothoraces.

Ventilation during continuous compressions or at 30:2 compression-to-ventilation ratio results in similar arterial oxygen and carbon dioxide levels in an experimental model of prolonged cardiac arrest

BACKGROUND

In refractory out-of-hospital cardiac arrest, transportation to hospital with continuous chest compressions (CCC) from a chest compression device and ventilation with 100% oxygen through an advanced airway is common practice. Despite this, many patients are hypoxic and hypercapnic on arrival, possibly related to suboptimal ventilation due to the counterpressure caused by the CCC. We hypothesized that a compression/ventilation ratio of 30:2 would provide better ventilation and gas exchange compared to asynchronous CCC during prolonged experimental cardiopulmonary resuscitation (CPR).

METHODS

We randomized 30 anaesthetized domestic swine (weight approximately 50 kg) with electrically induced ventricular fibrillation to the CCC or 30:2 group and bag-valve ventilation with a fraction of inspired oxygen (FiO₂) of 100%. We started CPR after a 5-min no-flow period and continued until 40 min from the induction of ventricular fibrillation. Chest compressions were performed with a Stryker Medical LUCAS® 2 mechanical chest compression device. We collected arterial blood gas samples every 5 min during the CPR, measured ventilation distribution during the CPR using electrical impedance tomography (EIT) and analysed post-mortem computed tomography (CT) scans for differences in lung aeration status.

RESULTS

The median (interquartile range [IQR]) partial pressure of oxygen (PaO₂) at 30 min was 110 (52-117) mmHg for the 30:2 group and 70 (40-171) mmHg for the CCC group. The median (IQR) partial pressure of carbon dioxide (PaCO₂) at 30 min was 70 (45-85) mmHg for the 30:2 group and 68 (42-84) mmHg for the CCC group. No statistically significant differences between the groups in PaO₂ (p = 0.40), PaCO₂ (p = 0.79), lactate (p = 0.37), mean arterial pressure (MAP) (p = 0.47) or EtCO₂ (p = 0.19) analysed with a linear mixed model were found. We found a deteriorating trend in PaO₂, EtCO₂ and MAP and rising PaCO₂ and lactate levels through the intervention. There were no differences between the groups in the distribution of ventilation in the EIT data or the post-mortem CT findings.

CONCLUSIONS

The 30:2 and CCC protocols resulted in similar gas exchange and lung pathology in an experimental prolonged mechanical CPR model.

Quality of chest compressions during prehospital resuscitation phase from scene arrival to ambulance transport in out-of-hospital cardiac arrest

AIM

Prehospital cardiopulmonary resuscitation is performed from scene arrival to hospital arrival. The diverse prehospital resuscitation phases can affect the quality of chest compressions. This study aimed to evaluate the dynamic changes in chest compression quality during prehospital resuscitation.

METHODS

Adult out-of-hospital cardiac arrest patients treated without prehospital return of spontaneous circulation were included in Seoul between July 2020 and September 2021. The chest compressions quality was assessed using a real-time chest compression feedback device. The prehospital phase was divided by key events during the prehospital resuscitation timeline (phase 1: first 2 min after initiation of chest compression, phase 2: from the end of phase 1 to 1 min prior to ambulance departure; phase 3: from 1 min before to 1 min after ambulance departure; phase 4: from the end of phase 3 to hospital arrival). The main outcome was no-flow fraction. The no-flow fraction between prehospital phases was compared using repeated-measure analysis of variance.

RESULTS

In total, 788 patients were included. Mean no-flow fraction was the highest in phase 3 (phase 1: 11.3% ± 13.8, phase 2: 19.3% ± 12.3, phase 3: 33.0% ± 34.9, phase 4: 18.7% ± 23.7, p < 0.001). The mean number of total no-flow events per minute was also the highest in phase 3. The minute-by-minute analysis showed that the no-flow fraction rapidly increased before ambulance departure and decreased during ambulance transport.

CONCLUSION

Dynamic changes in chest compression quality were observed during prehospital resuscitation phase. The no-flow fraction was the highest from 1 min before to 1 min after ambulance departure.

Cardiac Arrest Occurring in High-Rise Buildings: A Scoping Review

Out-of-hospital cardiac arrests (OHCAs) occurring in high-rise buildings are a challenge to Emergency Medical Services (EMS). Contemporary EMS guidelines lack specific recommendations for systems and practitioners regarding the approach to these patients. This scoping review aimed to map the body of literature pertaining to OHCAs in high-rise settings in order to clarify concepts and understanding and to identify knowledge gaps. Databases were searched from inception through to 6 May 2021 including OVID Medline, PubMed, Embase, CINAHL, and Scopus. Twenty-three articles were reviewed, comprising 8 manikin trials, 14 observational studies, and 1 mathematical modelling study. High-rise settings commonly have lower availability of bystanders and automatic external defibrillators (AEDs), while height constraints often lead to delays in EMS interventions and suboptimal cardiopulmonary resuscitation (CPR), scene access, and extrication. Four studies found return of spontaneous circulation (ROSC) rates to be significantly poorer, while seven studies found rates of survival-to-hospital discharge (n = 3) and neurologically favourable survival (n = 4) to be significantly lower in multistorey settings. Mechanical chest compression devices, transfer sheets, and strategic defibrillator placement were suggested as approaches to high-rise OHCA management. A shift to maximising on-scene treatment time, along with bundling novel prehospital interventions, could ameliorate some of these difficulties and improve clinical outcomes for patients.

Early mechanical cardiopulmonary resuscitation can improve outcomes in patients with non-traumatic cardiac arrest in the emergency department

Objective

To compare the outcomes of patients with non-traumatic cardiac arrest (CA) who received early versus late mechanical cardiopulmonary resuscitation (CPR) with the Lund University Cardiac Assist System (LUCAS) device in the emergency department (ED).

Methods

This was a retrospective observational study in the ED of a single medical center performed from May 2018 to December 2019; 68 patients with CA were eligible. We grouped the patients according to the time to initiating LUCAS use after CA into an early group (≤4 minutes) and late group (>4 minutes).

Results

The rate of return of spontaneous circulation (ROSC) was higher in the early group vs the late group (69.2% vs 52.4%, respectively). The 4-hour survival rate was significantly higher in the early group vs the late group (83.3% vs 45.5%, respectively), and CPR duration was significantly shorter in the early group (23.3 ± 12.5 vs 31.1 ± 14.8 minutes, respectively).

Conclusion

Early mechanical CPR can improve the success of achieving ROSC and the 4-hour survival rate in patients with non-traumatic CA in the ED, considering that more benefits were observed in patients who received early vs late LUCAS device therapy.

Testing mechanical chest compression devices of different design for their suitability for prehospital patient transport - a simulator-based study

Background

Mechanical chest compression (mCPR) offers advantages during transport under cardiopulmonary resuscitation. Little is known how devices of different design perform en-route. Aim of the study was to measure performance of mCPR devices of different construction-design during ground-based pre-hospital transport.

Methods

We tested animax mono (AM), autopulse (AP), corpuls cpr (CC) and LUCAS2 (L2). The route had 6 stages (transport on soft stretcher or gurney involving a stairwell, trips with turntable ladder, rescue basket and ambulance including loading/unloading). Stationary mCPR with the respective device served as control. A four-person team carried an intubated and bag-ventilated mannequin under mCPR to assess device-stability (displacement, pressure point correctness), compliance with 2015 ERC guideline criteria for high-quality chest compressions (frequency, proportion of recommended pressure depth and compression-ventilation ratio) and user satisfaction (by standardized questionnaire).

Results

All devices performed comparable to stationary use. Displacement rates ranged from 83% (AM) to 11% (L2). Two incorrect pressure points occurred over 15,962 compressions (0.013%). Guideline-compliant pressure depth was > 90% in all devices. Electrically powered devices showed constant frequencies while muscle-powered AM showed more variability (median 100/min, interquartile range 9). Although physical effort of AM use was comparable (median 4.0 vs. 4.5 on visual scale up to 10), participants preferred electrical devices.

Conclusion

All devices showed good to very good performance although device-stability, guideline compliance and user satisfaction varied by design. Our results underline the importance to check stability and connection to patient under transport.

The feasibility of emergency medical technicians performing intermittent high-quality cardiopulmonary resuscitation

Background: Whether intermittent chest compressions have an effect on the quality of CPR is worthy of discussion. The purpose of this study was to investigate differences in the chest compression quality of emergency medical technicians (EMTs) performing cardiopulmonary resuscitation (CPR) with different rest intervals. Methods: Seventy male firefighters with EMT licenses participated in this study. Participants completed body composition measurements and three CPR quality tests, as follows: (1) CPR-uninterrupted for 10 minutes; (2) after 2 days of rest, CPR 10s-intermittent (CPR-10s), for 2 minutes each time and 5 cycles; (3) after another 2 days of rest, CPR 20s-intermittent (CPR-20s), for 2 minutes each time and 5 cycles. Results: Body composition results showed that body mass (BM), body mass index (BMI), upper limb muscle mass (ULMM), core muscle mass (CMM), and upper limb-core muscle mass (UL+CMM) were positively correlated with chest compression depth (CCD) (p < 0.05). Analysis of the three different modes of CPR quality analysis indicated significant differences in the chest compression fraction (CCF, F = 6.801, p = 0.001), chest compression rebound rate (CCRR, F = 3.919, p = 0.021), and ratings of perceived exertion (RPE, F = 23.815, p < 0.001). Among the different performance cycles of CPR-10s, significant differences were found in CCF, CCD, CCR (chest compression rate), and RPE (p < 0.05). On the other hand, among the different performance cycles of CPR-20s, significant differences were found in CCD, CCR, and RPE (p < 0.05). Moreover, the CCF, CCD, and RPE scores of the two tests reached significant differences in specific phases (p < 0.05). Conclusions: This study confirmed that the upper limb muscle mass or the weight of the upper body of EMTs is positively correlated with the quality of CPR. In addition, intermittent chest compressions with safe interruption intervals can reduce fatigue caused by long-term chest compressions and maintain better chest compression quality.

Effect of Ambulance Stretcher Bed Height Adjustment on CPR Quality and Rescuer Fatigue in a Laboratory Environment

Background: The quality of cardiopulmonary resuscitation (CPR) is closely related to the survival rate of a patient, and it is crucial to maintain the quality of CPR during the ambulance journey to the receiving hospital. The purpose of this study was to investigate the effects of different stretcher bed heights on operator CPR quality. Methods: In this randomized crossover trial, 16 male emergency medical technicians-paramedics (EMT-Ps) performed continuous chest compressions on a hemimorphic mannequin for 5 minutes, alternating between the current height of the stretcher bed on the ambulance (38 ± 1 cm) (S-38) and the height of the participant's midpoint of the patella (S-knee), where the stretcher bed surface is. Results: According to the analysis of the quality of CPR exercises with two different stretcher bed heights at 5 minutes of continuous chest compression, the mean chest compression depth (CCD) of the S-38 position (53.81 ± 1.91 cm) was significantly lower than that of the S-knee (55.12 ± 2.03 cm; p < 0.001). The mean chest compression rate (CCR) of the S-38 position (111.44 ± 3.44 beats/min) was significantly higher than that of the S-knee (109.63 ± 4.46 beats/min; p = 0.027). The mean of total chest compressions (TCC) of the S-38 position (557.44 ± 16.81 times) was significantly higher than that of the S-knee (548.24 ± 19.40 times; p = 0.029). The rating of perceived exertion (RPE) of the S-38 position was significantly higher than that of the S-knee (12.75 ± 1.91 %; p = 0.015). Only the chest compression rebound rate (CCRR) (S-38: 97.56 ± 4.63 % vs. S-knee: 98.31 ± 1.89 %, p = 0.401) and the chest compression fraction (CCF) (S-38: 98.44 ± 0.81 % vs. S-knee: 98.44 ± 0.96 %, p = 1.000) did not reach a significant difference. Conclusion: When a resuscitator is performing chest compressions in a standing position in an ambulance, the excessive downward leaning of the resuscitator's upper body affects CPR quality and increases fatigue. This study has verified that setting the stretcher bed of the ambulance at the knee height of the EMTs provides better CPR quality and lower fatigue.