Gerrit Jan Noordergraaf

Does use of the CPREzy™ involve more work than CPR without feedback?

AIM Feedback during CPR may facilitate quality in chest compressions, but has also been associated with caregiver complaints such as stiff wrists, the need for more force and increased fatigue. This concern about extra work is, when using the CPREzy with its own spring-loaded surface, particularly relevant in the face of an increased number of successive compressions. This manuscript evaluates the objective workloads for caregivers with and without the CPREzy. MATERIALS AND METHODS An air pressure driven, piston device was used to generate controlled compressions in a manikin model. The pressure was applied for chest compressions with each of the following: the cylindrical end of the piston, a wooden block as dummy for the CPREzy, and the CPREzy itself. Three manikins with subjectively different spring compliances were selected for the tests. Series of 20 compressions were performed over a wide range of pressures. RESULTS No additional force is required to achieve a given depth of compression with or without the CPREzy. However, some additional work is required, ranging from 21 to 26.5%. This work is caused by the longer compression distance associated with the need to compress two springs (e.g. the CPREzy and the chest wall) instead of one (e.g. the chest wall). CONCLUSION The subjective feeling of increased rescuer fatigue with the CPREzy can, at least in part, be attributed to the extra work required for compressing the spring of the CPREzy. Improved accuracy in chest compression depth is likely to be another, more significant, factor in rescuer fatigue.

Can first responders achieve and maintain normocapnia when sequentially ventilating with a bag-valve device and two oxygen-driven resuscitators? A controlled clinical trial in 104 patients

Background and objective: To evaluate the capability of first responders to achieve and maintain normal ventilation of the lungs of victims employing a bag-valve device and two oxygen-driven resuscitators. Methods: Prospective, controlled, blinded, single-centre clinical trial using a bag-valve device and one of two FR-300® devices, with 20 cmH2O working pressure, and flows of either 24 or 30 L min−1. One hundred and four patients were analysed. Induction of anaesthesia followed by ventilation of the lungs with a bag-valve device and an Oxylator® in manual and automatic modes performed by a fireman first responder. Each series was repeated for three conditions (anaesthesia; anaesthesia plus muscle relaxation, both with facemask; anaesthesia plus relaxation using an endotracheal tube). Results: Patients age 49 ± 17 yr; 47% males, 48-132 kg. Normocapnia was achieved and maintained in 66% (bag-valve device), 82% (Oxylator®). Conclusions: The use of an oxygen-driven device improves the ability of first responders to achieve and maintain normocapnia even when distracted. Use of the Oxylators® improves performance (P < 0.001) vs. the bag-valve device significantly.

Detection of a spontaneous pulse in photoplethysmograms during automated cardiopulmonary resuscitation in a porcine model

INTRODUCTION Reliable, non-invasive detection of return of spontaneous circulation (ROSC) with minimal interruptions to chest compressions would be valuable for high-quality cardiopulmonary resuscitation (CPR). We investigated the potential of photoplethysmography (PPG) to detect the presence of a spontaneous pulse during automated CPR in an animal study. METHODS Twelve anesthetized pigs were instrumented to monitor circulatory and respiratory parameters. Here we present the simultaneously recorded PPG and arterial blood pressure (ABP) signals. Ventricular fibrillation was induced, followed by 20 min of automated CPR and subsequent defibrillation. After defibrillation, pediatric-guidelines-style life support was given in cycles of 2 min. PPG and ABP waveforms were recorded during all stages of the protocol. Raw PPG waveforms were acquired with a custom-built photoplethysmograph controlling a commercial reflectance pulse oximetry probe attached to the nose. ABP was measured in the aorta. RESULTS In nine animals ROSC was achieved. Throughout the protocol, PPG and ABP frequency content showed strong resemblance. We demonstrate that (1) the PPG waveform allows for the detection of a spontaneous pulse during ventilation pauses, and that (2) frequency analysis of the PPG waveform allows for the detection of a spontaneous pulse and the determination of the pulse rate, even during ongoing chest compressions, if the pulse and compression rates are sufficiently distinct. CONCLUSIONS These results demonstrate the potential of PPG as a non-invasive means to detect pulse presence or absence, as well as pulse rate during CPR.

Photoplethysmography-Based Algorithm for Detection of Cardiogenic Output During Cardiopulmonary Resuscitation

Detecting return of spontaneous circulation (ROSC) during cardiopulmonary resuscitation (CPR) is challenging, time consuming, and requires interrupting chest compressions. Based on automated-CPR porcine data, we have developed an algorithm to support ROSC detection, which detects cardiogenic output during chest compressions via a photoplethysmography (PPG) signal. The algorithm can detect palpable and impalpable spontaneous pulses. A compression-free PPG signal which estimates the spontaneous pulse waveform, was obtained by subtracting the compression component, modeled by a harmonic series. The fundamental frequency of this series was the compression rate derived from the transthoracic impedance signal measured between the defibrillation pads. The amplitudes of the harmonic components were obtained via a least mean-square algorithm. The frequency spectrum of the compression-free PPG signal was estimated via an autoregressive model, and the relationship between the spectral peaks was analyzed to identify the pulse rate (PR). Resumed cardiogenic output could also be detected from a decrease in the baseline of the PPG signal, presumably caused by a redistribution of blood volume to the periphery. The algorithm indicated cardiogenic output when a PR or a redistribution of blood volume was detected. The algorithm indicated cardiogenic output with 94% specificity and 69% sensitivity compared to the retrospective ROSC detection of nine clinicians. Results showed that ROSC detection can be supported by combining the compression-free PPG signal with an indicator based on the detected PR and redistribution of blood volume.

Airway management concerns in patient with gastric banding procedures

Laparoscopic adjustable gastric band (LAGB) is considered a relatively safe and effective treatment for obesity. Even after weight loss patients with LAGB are at increased risk of pulmonary aspiration during induction of general anaesthesia, possibly due to LAGB-induced anatomical and functional changes. We present a case of aspiration in a patient with LAGB following significant weight loss and 14 h of preoperative fasting and review the literature. In the presence of LAGB we propose specific anaesthesia management at least consisting of anti-Trendelenburg positioning; avoidance of mask-ventilation; use of the local rapid sequence induction strategy with endotracheal intubation and fully awake extubation.

A ventilation technique for oxygenation and carbon dioxide elimination in CPR: Continuous insufflation of oxygen at three levels of pressure in a pig model

AIM Pulmonary ventilation remains an important part of cardiopulmonary resuscitation, affecting gas exchange and haemodynamics. We designed and studied an improved method of ventilation for CPR, constructed specifically to support both gas exchange and haemodynamics. This method uses continuous insufflation of oxygen at three levels of pressure, resulting in tri-level pressure ventilation (TLPV). We hypothesized that TLPV improves gas exchange and haemodynamics compared to manual gold standard ventilation (GSV). METHODS In 14 pigs, ventricular fibrillation was induced and automated CPR performed for 10 min with either TLPV or GSV. After defibrillation, CPR was repeated with the other ventilation method. Gas exchange and haemodynamics were monitored. Data are presented as mean±standard error of the mean. RESULTS TLPV was superior to GSV for PaO2 (163±36 mmHg difference; P=0.001), and peak AWP (-20±2 cmH2O difference; P=0.000) and higher for mean AWP (8±0.2 cmH2O difference; P=0.000). TLPV was comparable to GSV for CPP (5±3 mmHg difference; P=0.012), VCO2 (0.07±0.3 mL/min/kg difference; P=0.001), SvO2 (4±3%-point; P=0.001), mean carotid flow (-0.5±4 mL/min difference; P=0.016), and pHa (0.00±0.03 difference; P=0.002). The PaCO2 data do not provide a conclusive result (4±4 mmHg difference). CONCLUSION We conclude that the ventilation strategy with a tri-level pressure cycle performs comparable to an expert, manual ventilator in an automated-CPR swine model.

Dynamic prediction of ROSC: Is the art of prognostication in Resuscitation becoming science?

87 In this issue, Kim et al. challenge the reader with their anuscript entitled “Dynamic predication of patient outcomes uring ongoing cardiopulmonary resuscitation”.1 Those expecting alidation of a smart phone based App, have the concept right, but o need to be patient a little longer. The authors have chosen a core issue in resuscitation: when o start and when to stop.2 If we know, up front, whether what e intend to achieve could benefit that patient in their specific ituation at a specific point in time, imagine the impact on our art! Kim et al. use a standardized setting for this study. In their sysem, patients typically received BLS up to Emergency Department ED) admission, after which ACLS is started. Routine blood gas analsis is done at presentation. They limit themselves to patients with ngoing CPR at ED presentation, and with the first occurrence of OSC in the first 30 min of their treatment. Patients with ROSC at resentation, and those with ROSC after 30 min ACLS in the ED were xcluded from the main analysis. In essence, using data from some 727 patients, they created a odel which could predict ROSC likelihood and conditional probbilities for short and long term survival chance and quintessential oal of good neurological outcome. Specifically, this is the chance hat a specific patient, under the specific conditions at that moment n time within the ED has for these outcomes. In the model they sed parameters such as whether the arrest was witnessed, the nitial rhythm, ACLS duration and pCO2 at ED presentation.3,4 They hen used scenarios to test if the model would reproduce actual ndings. The authors note a number of interesting outcomes. Noteworhy are the biphasic survival probability for ROSC and the usefulness f an initial blood gas analysis. The first showed increasing ROSC hances from ED admission up to 10 min. Since in their study ALS as started at ED admission and the authors note that there are no ut-of-hospital TOR rules, delayed but advanced care in a controlled nvironment seems to offer ROSC opportunities. The authors also ntroduce blood gas values as variables: close to admission, which eflect both the prehospital as well as the initial ED care, and dd potential for ‘objectifying’ the internal environment and offer nsight in the potential for good outcome at that point.4 Physicians and scientists have sought the objective – right –

Epidural analgesia as part of a fast track recovery (ERAS) program for elective colonic surgery: just long enough

Abstract Background: Epidural analgesia (EA) has been suggested to be a key element within the enhanced recovery after surgery guidelines for elective colonic surgery (ERAS). However, divergent descriptions exist