Ventilation during cardiopulmonary resuscitation with mechanical chest compressions: How often are two insufflations being given during the 3-second ventilation pauses?

BACKGROUND: Mechanical chest compression devices in 30:2 mode provide 3-second pauses to allow for two insufflations. We aimed to determine how often two insufflations are provided in these ventilation pauses, in order to assess if prehospital providers are able to ventilate out-of-hospital cardiac arrest (OHCA) patients successfully during mechanical chest compressions. METHODS: Data from OHCA cases of the regional ambulance service of Utrecht, The Netherlands, were prospectively collected in the UTrecht studygroup for OPtimal registry of cardIAc arrest database (UTOPIA). Compression pauses and insufflations were visualized on thoracic impedance and waveform capnography signals recorded by manual defibrillators. Ventilation pauses were analyzed for number of insufflations, duration of the subintervals of the ventilation cycles, and ratio of successfully providing two insufflations over the course of the resuscitation. Generalized linear mixed effects models were used to accurately estimate proportions and means. RESULTS: In 250 cases, 8473 ventilation pauses were identified, of which 4305 (51%) included two insufflations. When corrected for non-independence of the data across repeated measures within the same subjects with a mixed effects analysis, two insufflations were successfully provided in 45% of ventilation pauses (95% CI: 40-50%). In 19% (95% CI: 16-22%) none were given. CONCLUSION: Providing two insufflations during pauses in mechanical chest compressions is mostly unsuccessful. We recommend developing strategies to improve giving insufflations when using mechanical chest compression devices. Increasing the pause duration might help to improve insufflation success.

Prehospital transdermal glyceryl trinitrate in patients with presumed acute stroke (MR ASAP): an ambulance-based, multicentre, randomised, open-label, blinded endpoint, phase 3 trial.

BACKGROUND: Pooled analyses of previous randomised studies have suggested that very early treatment with glyceryl trinitrate (also known as nitroglycerin) improves functional outcome in patients with acute ischaemic stroke or intracerebral haemorrhage, but this finding was not confirmed in a more recent trial (RIGHT-2). We aimed to assess whether patients with presumed acute stroke benefit from glyceryl tr initrate started within 3 h after symptom onset. METHODS: MR ASAP was a phase 3, randomised, open-label, blinded endpoint trial done at six ambulance services serving 18 hospitals in the Netherlands. Eligible participants (aged ≥18 years) had a probable diagnosis of acute stroke (as assessed by a paramedic), a face-arm-speech-time test score of 2 or 3, systolic blood pressure of at least 140 mm Hg, and could start treatment within 3 h of symptom onset. Participants were randomly assigned (1:1) by ambulance personnel, using a secure web-based electronic application with random block sizes stratified by ambulance service, to receive either transdermal glyceryl trinitrate 5 mg/day for 24 h plus standard care (glyceryl trinitrate group) or to standard care alone (control group) in the prehospital setting. Informed consent was deferred until after arrival at the hospital. The primary outcome was functional outcome assessed with the modified Rankin Scale (mRS) at 90 days. Safety outcomes included death within 7 days, death within 90 days, and serious adverse events. Analyses were based on modified intention to treat, and treatment effects were expressed as odds ratios (ORs) or common ORs, with adjustment for baseline prognostic factors. We separately analysed the total population and the target population (ie, patients with intracerebral haemorrhage, ischaemic stroke, or transient ischaemic attack). The target sample size was 1400 patients. The trial is registered as ISRCTN99503308. FINDINGS: On June 24, 2021, the MR ASAP trial was prematurely terminated on the advice of the data and safety monitoring board, with recruitment stopped because of safety concerns in patients with intracerebral haemorrhage. Between April 4, 2018, and Feb 12, 2021, 380 patients were randomly allocated to a study group. 325 provided informed consent or died before consent could be obtained, of whom 170 were assigned to the glyceryl trinitrate group and 155 to the control group. These patients were included in the total population. 201 patients (62%) had ischaemic stroke, 34 (10%) transient ischaemic attack, 56 (17%) intracerebral haemorrhage, and 34 (10%) a stroke-mimicking condition. In the total population (n=325), the median mRS score at 90 days was 2 (IQR 1-4) in both the glyceryl trinitrate and control groups (adjusted common OR 0·97 [95% CI 0·65-1·47]). In the target population (n=291), the 90-day mRS score was 2 (2-4) in the glyceryl trinitrate group and 3 (1-4) in the control group (0·92 [0·59-1·43]). In the total population, there were no differences between the two study groups with respect to death within 90 days (adjusted OR 1·07 [0·53-2·14]) or serious adverse events (unadjusted OR 1·23 [0·76-1·99]). In patients with intracerebral haemorrhage, 12 (34%) of 35 patients allocated to glyceryl trinitrate versus two (10%) of 21 allocated to the control group died within 7 days (adjusted OR 5·91 [0·78-44·81]); death within 90 days occurred in 16 (46%) of 35 in the glyceryl trinitrate group and 11 (55%) of 20 in the control group (adjusted OR 0·87 [0·18-4·17]). INTERPRETATION: We found no sign of benefit of transdermal glyceryl trinitrate started within 3 h of symptom onset in the prehospital setting in patients with presumed acute stroke. The signal of potential early harm of glyceryl trinitrate in patients with intracerebral haemorrhage suggests that glyceryl trinitrate should be avoided in this setting. FUNDING: The Collaboration for New Treatments of Acute Stroke consortium, the Brain Foundation Netherlands, the Ministry of Economic Affairs, Stryker, Medtronic, Cerenovus, and the Dutch Heart Foundation.

Optimizing airway management and ventilation during prehospital advanced life support in out-of-hospital cardiac arrest: A narrative review.

Airway management and ventilation are essential components of cardiopulmonary resuscitation to achieve oxygen delivery in order to prevent hypoxic injury and increase the chance of survival. Weighing the relative benefits and downsides, the best approach is a staged strategy; start with a focus on high-quality chest compressions and defibrillation, then optimize mask ventilation while preparing for advanced airway management with a supraglottic airway device. Endotracheal intubation can still be indicated, but has the largest downsides of all advanced airway techniques. Whichever stage of airway management, ventilation and chest compression quality should be closely monitored. Capnography has many advantages and should be used routinely. Optimizing ventilation strategies, harmonizing ventilation with mechanical chest compression devices, and implementation in complex and stressful environments are challenges we need to face through collaborative innovation, research, and implementation.

Per-Protocol and Pre-Defined population analysis of the LINC study.

OBJECTIVE: To perform two predefined sub-group analyses within the LINC study and evaluate if the results were supportive of the previous reported intention to treat (ITT) analysis. METHODS: Predefined subgroup analyses from the previously published LINC study were performed. The Per-Protocol population (PPP) included the randomized patients included in the ITT-population but excluding those with violated inclusion or exclusion criteria and those that did not get the actual treatment to which the patient was randomized. In the Pre-Defined population (PDP) analyses patients were also excluded if the dispatch time to ambulance arrival at the address exceeded 12 min, there was a non-witnessed cardiac arrest, or if it was not possible to determine whether the arrest was witnessed or not, and those cases where LUCAS was not brought to the scene at the first instance. RESULTS: After exclusion from the 2589 patients within the ITT-population, the Per-Protocol analysis was performed in 2370 patients and the Pre-Defined analysis within 1133 patients. There was no significant difference in 4-h survival of patients between the mechanical-CPR group and the manual-CPR group in the Per-Protocol population; 279 of 1172 patients (23.8%) versus 281 of 1198 patients (23.5%) (risk difference -0.35%, 95% C.I. -3.1 to 3.8, p=0.85) or in the Pre-Defined population; 176 of 567 patients (31.0%) versus 192 of 566 patients (33.9%) (risk difference -2.88%, 95% C.I. -8.3 to 2.6, p=0.31). There was no difference in any of the second outcome variables analyzed in the Pre-Protocol or Pre-Defined populations. CONCLUSIONS: The results from these predefined sub-group analyses of the LINC study population did not show any difference in 4h survival or in secondary outcome variables between patients treated with mechanical-CPR or manual-CPR. This is consistent with the previously published ITT analysis.

Mechanical chest compressions improved aspects of CPR in the LINC trial.

AIM: We studied resuscitation process metrics in patients with out-of-hospital cardiac arrest enrolled in a randomized trial comparing one protocol designed to best use a mechanical CPR device, with another based on the 2005 European Resuscitation Council guidelines for manual CPR. METHODS: We analyzed clinical data, ECG signals, and transthoracic impedance signals for a subset of the patients in the LUCAS in Cardiac Arrest (LINC) trial, including 124 patients randomized to mechanical and 82 to manual CPR. Chest compression fraction (CCF) was defined as the fraction of time during cardiac arrest that chest compressions were administered. RESULTS: Patients in the mechanical CPR group had a higher CCF than those in the manual CPR group [0.84 (0.78, 0.91) vs. 0.79 (0.70, 0.86), p < 0.001]. The median duration of their pauses for defibrillation was also shorter [0 s (0, 6.0) vs. 10.0 s (7.0, 14.3), p < 0.001]. Compressions were interrupted for a median of 36.0 s to apply the compression device. There was no difference between groups in duration of the longest pause in compressions [32.5s vs. 26.0 s, p = 0.24], number of compressions received per minute [86.5 vs. 88.3, p = 0.47], defibrillation success rate [73.2% vs. 81.0%, p = 0.15], or refibrillation rate [74% vs. 77%, p = 0.79]. CONCLUSIONS: A protocol using mechanical chest compression devices reduced interruptions in chest compressions, and enabled defibrillation during ongoing compressions, without adversely affecting other resuscitation process metrics. Future emphasis on optimizing device deployment may be beneficial.

Fast assessment and management of chest pain without ST-elevation in the pre-hospital gateway: rationale and design.

BACKGROUND: For chest pain patients without ST-segment elevation in the pre-hospital setting, current clinical guidelines merely offer in-hospital risk stratification and management, as opposed to chest pain patients with ST-segment elevation for whom there is a straightforward pre-hospital strategy for diagnosis, medication regimen and logistics. The FAMOUS TRIAGE study will assess the effects of introducing a pre-hospital triage system that reliably stratifies chest pain patients without ST-segment elevation into 1) patients at high risk for NSTEMI requiring a direct transfer to a PCI-hospital; 2) patients at intermediate risk for a major adverse cardiac event (MACE) who could be evaluated at the nearest non-PCI hospital; and 3) patients at low risk for MACE (benign non-cardiac chest pain) who could have further evaluation at home or in a primary care setting. METHODS: The FAMOUS TRIAGE study will be performed in three phases. In the first phase an appropriate pre-hospital risk stratification tool will be designed for chest pain patients without ST-segment elevation by means of a retrospective and a prospective study. The second phase of the project represents the external validation of the risk stratification models, and in the third and final phase an optimal risk stratification tool will be implemented into clinical practice. Clinical and economical endpoints before and after implementation of the pre-hospital risk stratification tool will be compared to assess clinical benefit and cost-effectiveness. CONCLUSION: The FAMOUS TRIAGE project is a triple phase study that aims to optimize the pre-hospital management of chest pain patients without ST-segment elevation by providing tools for pre-hospital identification of NSTEMI or exclusion of acute coronary syndrome at home. TRIAL ID: NTR4205. Dutch Trial Register [http://www.trialregister.nl]: trial number 4205.

Mechanical chest compressions and simultaneous defibrillation vs conventional cardiopulmonary resuscitation in out-of-hospital cardiac arrest: the LINC randomized trial.

IMPORTANCE: A strategy using mechanical chest compressions might improve the poor outcome in out-of-hospital cardiac arrest, but such a strategy has not been tested in large clinical trials. OBJECTIVE: To determine whether administering mechanical chest compressions with defibrillation during ongoing compressions (mechanical CPR), compared with manual cardiopulmonary resuscitation (manual CPR), according to guidelines, would improve 4-hour survival. DESIGN, SETTING, AND PARTICIPANTS: Multicenter randomized clinical trial of 2589 patients with out-of-hospital cardiac arrest conducted between January 2008 and February 2013 in 4 Swedish, 1 British, and 1 Dutch ambulance services and their referring hospitals. Duration of follow-up was 6 months. INTERVENTIONS: Patients were randomized to receive either mechanical chest compressions (LUCAS Chest Compression System, Physio-Control/Jolife AB) combined with defibrillation during ongoing compressions (n = 1300) or to manual CPR according to guidelines (n = 1289). MAIN OUTCOMES AND MEASURES: Four-hour survival, with secondary end points of survival up to 6 months with good neurological outcome using the Cerebral Performance Category (CPC) score. A CPC score of 1 or 2 was classified as a good outcome. RESULTS: Four-hour survival was achieved in 307 patients (23.6%) with mechanical CPR and 305 (23.7%) with manual CPR (risk difference, -0.05%; 95% CI, -3.3% to 3.2%; P > .99). Survival with a CPC score of 1 or 2 occurred in 98 (7.5%) vs 82 (6.4%) (risk difference, 1.18%; 95% CI, -0.78% to 3.1%) at intensive care unit discharge, in 108 (8.3%) vs 100 (7.8%) (risk difference, 0.55%; 95% CI, -1.5% to 2.6%) at hospital discharge, in 105 (8.1%) vs 94 (7.3%) (risk difference, 0.78%; 95% CI, -1.3% to 2.8%) at 1 month, and in 110 (8.5%) vs 98 (7.6%) (risk difference, 0.86%; 95% CI, -1.2% to 3.0%) at 6 months with mechanical CPR and manual CPR, respectively. Among patients surviving at 6 months, 99% in the mechanical CPR group and 94% in the manual CPR group had CPC scores of 1 or 2. CONCLUSIONS AND RELEVANCE: Among adults with out-of-hospital cardiac arrest, there was no significant difference in 4-hour survival between patients treated with the mechanical CPR algorithm or those treated with guideline-adherent manual CPR. The vast majority of survivors in both groups had good neurological outcomes by 6 months. In clinical practice, mechanical CPR using the presented algorithm did not result in improved effectiveness compared with manual CPR. TRIAL REGISTRATION: clinicaltrials.gov Identifier: NCT00609778.

The study protocol for the LINC (LUCAS in cardiac arrest) study: a study comparing conventional adult out-of-hospital cardiopulmonary resuscitation with a concept with mechanical chest compressions and simultaneous defibrillation.

BACKGROUND: The LUCAS™ device delivers mechanical chest compressions that have been shown in experimental studies to improve perfusion pressures to the brain and heart as well as augmenting cerebral blood flow and end tidal CO2, compared with results from standard manual cardiopulmonary resuscitation (CPR). Two randomised pilot studies in out-of-hospital cardiac arrest patients have not shown improved outcome when compared with manual CPR. There remains evidence from small case series that the device can be potentially beneficial compared with manual chest compressions in specific situations. This multicentre study is designed to evaluate the efficacy and safety of mechanical chest compressions with the LUCAS™ device whilst allowing defibrillation during on-going CPR, and comparing the results with those of conventional resuscitation. METHODS/DESIGN: This article describes the design and protocol of the LINC-study which is a randomised controlled multicentre study of 2500 out-of-hospital cardiac arrest patients. The study has been registered at ClinicalTrials.gov (http://clinicaltrials.gov/ct2/show/NCT00609778?term=LINC&rank=1). RESULTS: Primary endpoint is four-hour survival after successful restoration of spontaneous circulation. The safety aspect is being evaluated by post mortem examinations in 300 patients that may reflect injuries from CPR. CONCLUSION: This large multicentre study will contribute to the evaluation of mechanical chest compression in CPR and specifically to the efficacy and safety of the LUCAS™ device when used in association with defibrillation during on-going CPR.