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Background: Timely medical management and evacuation of critically ill or injured patients from austere environments or maritime vessels is often achieved by helicopter hoist operations. When indicated, intubation is performed onsite to restore and sustain patient physiology and to facilitate safe transport. We aimed to describe the characteristics of helicopter hoist operations (HHOs) with intubated patients in a physician staffed SAR helicopter service and to identify learning points for future missions., Methods: The Norwegian national SAR database and local medical journal systems on six SAR helicopter bases were searched for data on hoisted intubated patients from January 2011 to April 2024., Results: From a total of 18,710 missions, we registered 2,423 helicopter hoist operations with patients as human external cargo. In 54 hoist operations (2%) the patients were intubated prior to hoisting. We observed an increasing number of both HHOs in general and HHOs with intubated patients over time. The intubated HHO patients were in an overall critical state, with a median NACA score of 6 and a median GCS of 3 before intubation. Trauma was the main cause of intubation (n = 32). Twenty-five patients presented with cardiac arrest, 13 of whom were hoisted with an ongoing mechanical chest compression device. During the hoist operation, 34 patients were ventilated manually, and 20 patients were connected to an automatic ventilator. Monitoring of vital parameters during hoisting varied from none to fully monitored patients including invasive arterial blood pressure. Twenty-eight patients, seven of whom presented with initial cardiac arrest, survived to hospital discharge., Conclusions: HHOs with intubated patients are rare but increasingly occurring events in our service. Owing to the infrequency, complexity and risk factors involved, these operations should be governed by specific operating procedures and trained regularly to be performed safely. HHOs with intubated patients represents a favourable alternative in situations where terrestrial transport is associated with significant time delay or additional risk to the patient or the rescuers., Competing Interests: Declarations. Ethics approval: The study was approved by the Data Protection Officer at Oslo University Hospital (reference 24/09587) and was by the Regional Ethics Committee (REK Sør-Øst, reference 767917) deemed as not applicable for clinical trial registration. Consent for publication: Not applicable. Competing interests: The authors declare no competing interests., (© 2024. The Author(s).)

Background and Aims: Chest compressions generating good perfusion during cardiopulmonary resuscitation (CPR) in cardiac arrest patients are critical for positive patient outcomes. Conventional wisdom advises minimizing compression pauses because several compressions are required to recover arterial blood pressure (ABP) back to pre-pause values. Our study examines how compression pauses influence ABP recovery post-pause in out-of-hospital cardiac arrest., Methods: We analyzed data from a subset of a prospective, randomized LUCAS 2 Active Decompression trial. Patients were treated by an anesthesiologist-staffed rapid response car program in Oslo, Norway (2015-2017) with mechanical chest compressions using the LUCAS device at 102 compressions/min. Patients with an ABP signal during CPR and at least one compression pause >2 sec were included. Arterial cannulation, compression pauses, and ECG during the pause were verified by physician review of patient records and physiological signals. Pauses were excluded if return of spontaneous circulation occurred during the pause (pressure pulses associated with ECG complexes). Compression, mean, and decompression ABP for 10 compressions before/after each pause and the mean ABP during the pause were measured with custom MATLAB code. The relationship between pause duration and ABP recovery was investigated using linear regression., Results: We included 56 patients with a total of 271 pauses (pause duration: median = 11 sec, Q1 = 7 sec, Q3 = 18 sec). Mean ABP dropped from 53 ± 10 mmHg for the last pre-pause compression to 33 ± 7 mmHg during the pause. Compression and mean ABP recovered to >90% of pre-pause pressure within 2 compressions, or 1.7 sec. Pause duration did not affect the recovery of ABP post-pause (R 2 : 0.05, 0.03, 0.01 for compression, mean, and decompression ABP, respectively)., Conclusions: ABP generated by mechanical CPR recovered quickly after pauses. Recovery of ABP after a pause was independent of pause duration., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: “Lars Wik reports financial support was provided by Stryker. Per Olav Berve reports financial support was provided by Norwegian Association of Heart and Lung Patients. Elisabete Aramendi reports financial support was provided by Spain Ministry of Science and Innovation, State Research Agency. Andoni Elola reports financial support was provided by Spain Ministry of Science and Innovation, State Research Agency. Rose Yin, Tyson Taylor, Rob Walker, and Fred Chapman report a relationship with Stryker that includes: employment. Lars Wik reports a relationship with Stryker that includes: consulting or advisory, funding grants, and travel reimbursement. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.”., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Background: Both skeletal and visceral injuries are reported after cardiopulmonary resuscitation (CPR). This subgroup analysis of a randomized clinical study describes/compares autopsy documented injury patterns caused by two mechanical, piston-based chest compression devices: standard LUCAS® 2 (control) and LUCAS® 2 with active decompression (AD, intervention) in non-survivors with out-of-hospital cardiac arrest (CA)., Method: We compared injuries documented by autopsies (medical/forensic) after control and intervention CPR based on written relatives consent to use patients' data. The pathologists were blinded for the device used. The cause of CA and injuries reported were based on a prespecified study autopsy template. We used Pearson's chi-squared test and logistic regression analysis with an alpha level of 0.05., Results: 221 patients were included in the main study (April 2015-April 2017) and 207 did not survive. Of these, 114 (55%, 64 control and 50 intervention) underwent medical ( N  = 73) or forensic ( N  = 41) autopsy. The cause of CA was cardiac 53%, respiratory 17%, overdose/intoxication 14%, ruptured aorta 10%, neurological 1%, and other 5%. There were no differences between control and intervention in the incidence of rib fractures (67% vs 72%; p -value = 0.58), or sternal fractures (44% vs 48%; p -value = 0.65), respectively. The most frequent non-skeletal complication was bleeding (26% of all patients) and intrathoracic was the most common location. Ten of the 114 patients had internal organ injuries, where lungs were most affected., Conclusion: In non-survivors of OHCA patients, the most frequent cause of cardiac arrest was cardiogenic. Skeletal and non-skeletal fractures/injuries were found in both control and intervention groups. Bleeding was the most common non-skeletal complication. Internal organ injuries were rare., (© 2023 The Author(s).)

Background: Active compression-decompression cardiopulmonary resuscitation (ACD-CPR) utilises a suction cup to lift the chest-wall actively during the decompression phase (AD). We hypothesised that mechanical ACD-CPR (Intervention), with AD up to 30 mm above the sternal resting position, would generate better haemodynamic results than standard mechanical CPR (Control)., Methods: This out-of-hospital adult non-traumatic cardiac arrest trial was prospective, block-randomised and non-blinded. We included intubated patients with capnography recorded during mechanical CPR. Exclusion criteria were pregnancy, prisoners, and prior chest surgery. The primary endpoint was maximum tidal carbon dioxide partial pressure (p MT CO 2 ) and secondary endpoints were oxygen saturation of cerebral tissue (SctO 2 ), invasive arterial blood pressures and CPR-related injuries. Intervention device lifting force performance was categorised as Complete AD (≥30 Newtons) or Incomplete AD (≤10 Newtons). Haemodynamic data, analysed as one measurement for each parameter per ventilation (Observation Unit, OU) with non-linear regression statistics are reported as mean (standard deviation). A two-sided p-value < 0.05 was considered as statistically significant., Results: Of 221 enrolled patients, 210 were deemed eligible (Control 109, Intervention 101). The Control vs. Intervention results showed no significant differences for p MT CO 2 : 29(17) vs 29(18) mmHg (p = 0.86), blood pressures during compressions: 111(45) vs. 101(68) mmHg (p = 0.93) and decompressions: 21(20) vs. 18(18) mmHg (p = 0.93) or for SctO 2 %: 55(36) vs. 57(9) (p = 0.42). The 48 patients who received Complete AD in > 50% of their OUs had higher SctO 2 than Control patients: 58(11) vs. 55(36)% (p < 0.001)., Conclusions: Mechanical ACD-CPR provided similar haemodynamic results to standard mechanical CPR. The Intervention device did not consistently provide Complete AD., Clinical Trial Registration: ClinicalTrials.gov identifier (NCT number): NCT02479152. The Haemodynamic Effects of Mechanical Standard and Active Chest Compression-decompression During Out-of-hospital CPR., Competing Interests: Declaration of Competing Interest LW was PI in the Zoll Medical funded CIRC study and holds patents via Oslo University Hospital (Inven2). He is a member of the medical advisory board of Stryker/Physio-Control. At the time of the study, BMH was employed by Stryker/Jolife AB, which manufactures the LUCAS device, LIFEPAK 15 and CODE-STAT. In addition, JC did analysis and data work for the study that was funded by Stryker/Jolife AB. POB, TS, HK and JKJ declare no conflicts of interests., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Background and Aim: Measuring tidal volumes (TV) during bag-valve ventilation is challenging in the clinical setting. The ventilation waveform amplitude of the transthoracic impedance (TTI-amplitude) correlates well with TV for an individual, but poorer between patients. We hypothesized that TV to TTI-amplitude relations could be improved when adjusted for morphometric variables like body mass index (BMI), gender or age, and that TTI-amplitude cut-offs for ventilations with adequate TV (>400ml) could be established., Materials and Methods: Twenty-one consenting adults (9 female, and 9 overall overweight) during positive pressure ventilation in anaesthesia before scheduled surgery were included. Seventeen ventilator modes were used (⩾ five breaths per mode) to adjust different TVs (150-800 ml), ventilation frequencies (10-30 min -1 ) and insufflation times (0.5-3.5 s). TTI from the defibrillation pads was filtered to obtain ventilation TTI-amplitudes. Linear regression models were fitted between target and explanatory variables, and compared (coefficient of determination, R 2 )., Results: The TV to TTI-amplitude slope was 1.39 Ω/l (R 2 =0.52), with significant differences (p<0.05) between male/female (1.04 Ω/l vs 1.84 Ω/l) and normal/overweight subjects (1.65 Ω/l vs 1.04 Ω/l). The median (interquartile range) TTI-amplitude cut-off for adequate TV was 0.51 Ω(0.14-1.20) with significant differences between males and females (0.58 Ω/0.39 Ω), and normal and overweight subjects (0.52 Ω/0.46 Ω). The TV to TTI-amplitude model improved (R 2 =0.66) when BMI, age and gender were included., Conclusions: TTI-amplitude to TV relations were established and cut-offs for ventilations with adequate TV determined. Patient morphometric variables related to gender, age and BMI explain part of the variability in the measurements., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Goal: Identifying the circulation state during out-of-hospital cardiac arrest (OHCA) is essential to determine what life-saving therapies to apply. Currently algorithms discriminate circulation (pulsed rhythms, PR) from no circulation (pulseless electrical activity, PEA), but PEA can be classified into true (TPEA) and pseudo (PPEA) depending on cardiac contractility. This study introduces multi-class algorithms to automatically determine circulation states during OHCA using the signals available in defibrillators., Methods: A cohort of 60 OHCA cases were used to extract a dataset of 2506 5-s segments, labeled as PR (1463), PPEA (364) and TPEA (679) using the invasive blood pressure, experimentally recorded through a radial/femoral cannulation. A multimodal algorithm using features obtained from the electrocardiogram, the thoracic impedance and the capnogram was designed. A random forest model was trained to discriminate three (TPEA/PPEA/PR) and two (PEA/PR) circulation states. The models were evaluated using repeated patient-wise 5-fold cross-validation, with the unweighted mean of sensitivities (UMS) and F 1 -score as performance metrics., Results: The best model for 3-class had a median (interquartile range, IQR) UMS and F 1 of 69.0% (68.0-70.1) and 61.7% (61.0-62.5), respectively. The best two class classifier had median (IQR) UMS and F 1 of 83.9% (82.9-84.5) and 76.2% (75.0-76.9), outperforming all previous proposals in over 3-points in UMS., Conclusions: The first multiclass OHCA circulation state classifier was demonstrated. The method improved previous algorithms for binary pulse/no-pulse decisions., Significance: Automatic multiclass circulation state classification during OHCA could contribute to improve cardiac arrest therapy and improve survival rates.

Compressions during the insufflation phase of ventilations may cause severe pulmonary injury during cardiopulmonary resuscitation (CPR). Transthoracic impedance (TTI) could be used to evaluate how chest compressions are aligned with ventilations if the insufflation phase could be identified in the TTI waveform without chest compression artifacts. Therefore, the aim of this study was to determine whether and how the insufflation phase could be precisely identified during TTI. We synchronously measured TTI and airway pressure (Paw) in 21 consenting anaesthetised patients, TTI through the defibrillator pads and Paw by connecting the monitor-defibrillator's pressure-line to the endotracheal tube filter. Volume control mode with seventeen different settings were used (5-10 ventilations/setting): Six volumes (150-800 mL) with 12 min -1 frequency, four frequencies (10, 12, 22 and 30 min -1 ) with 400 mL volume, and seven inspiratory times (0.5-3.5 s ) with 400 mL/10 min -1 volume/frequency. Median time differences (quartile range) between timing of expiration onset in the Paw-line (Paw EO ) and the TTI peak and TTI maximum downslope were measured. TTI peak and Paw EO time difference was 579 (432-723) m s for 12 min -1 , independent of volume, with a negative relation to frequency, and it increased linearly with inspiratory time (slope 0.47, R 2 = 0.72). Paw EO and TTI maximum downslope time difference was between -69 and 84 m s for any ventilation setting (time aligned). It was independent ( R 2 < 0.01) of volume, frequency and inspiratory time, with global median values of -47 (-153-65) m s , -40 (-168-68) m s and 20 (-93-128) m s , for varying volume, frequency and inspiratory time, respectively. The TTI peak is not aligned with the start of exhalation, but the TTI maximum downslope is. This knowledge could help with identifying the ideal ventilation pattern during CPR.