Effect of rescue breathing during cardiopulmonary resuscitation on lung function after restoration of spontaneous circulation in a porcine model of prolonged cardiac arrest

Can a Glove-Coach Technology Significantly Increase the Efficacy of Cardiopulmonary Resuscitation on Non-healthcare Professionals? A Controlled Trial

Introduction: Cardiovascular accidents are the world's leading cause of death. A good quality cardiopulmonary resuscitation (CPR) can reduce cardiac arrest-associated mortality. This study aims to test the coaching system of a wearable glove, providing instructions during out-of-hospital CPR. Materials and Methods: We performed a single-blind, controlled trial to test non-healthcare professionals during a simulated CPR performed on an electronic mannequin. The no-glove group was the control. The primary outcome was to compare the accuracy of depth and frequency of two simulated CPR sessions. Secondary outcomes were to compare the decay of CPR performance and the percentage of the duration of accurate CPR. Results: About 130 volunteers were allocated to 1:1 ratio in both groups; mean age was 36 ± 15 years (min-max 21-64) and 62 (48%) were men; 600 chest compressions were performed, and 571 chest compressions were analyzed. The mean frequency in the glove group was 117.67 vs. 103.02 rpm in the control group (p < 0.001). The appropriate rate cycle was 92.4% in the glove group vs. 71% in the control group, with a difference of 21.4% (p < 0.001). Mean compression depth in the glove group was 52.11 vs. 55.17 mm in the control group (p < 0.001). A mean reduction of compression depth over time of 5.3 mm/min was observed in the control group vs. 0.83 mm/min of reduction in the glove group. Conclusion: Visual and acoustic feedbacks provided through the utilization of the glove's coaching system were useful for non-healthcare professionals' CPR performance.

Compression depth of 30 mm has similar efficacy and fewer complications versus 50 mm during mechanical chest compression with miniaturized chest compressor in a porcine model of cardiac arrest

Background

Current guidelines recommend a 50 mm or greater compression depth for manual chest compression in adults. However, whether this uniform compression depth is a suitable requirement for mechanical CPR remains to be determined. We hypothesized that a relatively shallow compression depth (30 mm) would have similar hemodynamic efficacy but fewer complications versus the standard compression depth (50 mm) during mechanical cardiopulmonary resuscitation (CPR) with the miniaturized chest compressor (MCC) in a porcine model.

Methods

In the current study, we used a total of 16 domestic male pigs (38±2 kg). All pigs were exposed to 7 min of ventricular fibrillation (VF) followed by 5 min of CPR. Then the animals were randomly assigned to the shallow (30 mm) group and the standard (50 mm) group. At the second min of CPR, every pig was given epinephrine (20 µg/kg) through the femoral vein and repeated every 3 min. First defibrillation was delivered with a single 120 J shock at 5 min of CPR. Hemodynamics, carotid blood flow (CBF), end-tidal carbon dioxide (ETCO₂), coronary perfusion pressure (CPP), intrathoracic pressure (ITP) and arterial blood gas were measured. Rib fractures and lung injuries, as indicated by ground-glass opacification (GGO), as well as intense parenchymal opacification (IPO), were assessed and calculated by quantitative computed tomography (QCT) scan.

Results

We found no significant differences in CPP, CBF, or ETCO₂ between the both groups throughout the CPR period. After administration of epinephrine, the CPP of all animals increased while ETCO₂ and CBF decreased during CPR. A significantly lower intrathoracic positive pressure (ITPP) and systolic artery pressure (SAP) were measured in the shallow group at the first min of CPR. However, we didn’t find remarkable differences in these values between the both groups for the next 4 min of CPR. All animals were successfully resuscitated. The shallow group had significantly lower IPO QCT scores compared with the standard group. We found no significant differences in GGO QCT scores after resuscitation between both groups.

Conclusions

Relatively shallow compression depth has similar hemodynamic efficacy but fewer complications versus the standard compression depth.

Duty cycle of 33% increases cardiac output during cardiopulmonary resuscitation

BACKGROUND

The aim of this study was to investigate whether 33% duty cycle increases end-tidal carbon dioxide (ETCO2) level, a surrogate measurement for cardiac output during cardiopulmonary resuscitation (CPR), compared with 50% duty cycle.

METHODS

Six pigs were randomly assigned to the DC33 or DC50 group. After 3 min of induced ventricular fibrillation (VF), CPR was performed for 5 min with 33% duty cycle (DC33 group) or with 50% duty cycle (DC50 group) (phase I). Defibrillation was delivered until return of spontaneous circulation (ROSC) thereafter. After 30 min of stabilization, the animals were re-assigned to the opposite groups. VF was induced again, and CPR was performed (phase II). The primary outcome was ETCO2 during CPR, and the secondary outcomes were coronary perfusion pressure (CPP), systolic arterial pressure (SAP), diastolic arterial pressure (DAP), and right atrial pressure (RAP).

RESULTS

Mean ETCO2 was higher in the DC33 group compared with the DC50 group (22.5 mmHg vs 21.5 mmHg, P = 0.018). In a linear mixed model, 33% duty cycle increased ETCO2 by 1.0 mmHg compared with 50% duty cycle (P < 0.001). ETCO2 increased over time in the DC33 group [0.6 mmHg/min] while ETCO2 decreased in the DC50 group [-0.6 mmHg/min] (P < 0.001). Duty cycle of 33% increased SAP (6.0 mmHg, P < 0.001), DAP (8.9 mmHg, P < 0.001) RAP (2.6 mmHg, P < 0.001) and CPP (4.7 mmHg, P < 0.001) compared with the duty cycle of 50%.

CONCLUSION

Duty cycle of 33% increased ETCO2, a surrogate measurement for cardiac output during CPR, compared with duty cycle of 50%. Moreover, ETCO2 increased over time during CPR with 33% duty cycle while ETCO2 decreased with 50% duty cycle.

Effect of mild hypothermia on lung injury after cardiac arrest in swine based on lung ultrasound

BACKGROUND

Lung injury is common in post-cardiac arrest syndrome, and is associated with increased morbidity and mortality. The aim of this study was to evaluate the effect of mild hypothermia on lung injury after cardiac arrest in swine based on lung ultrasound.

METHODS

Twenty-three male domestic swine weighing 36 ± 2 kg were randomly assigned to three groups: therapeutic hypothermia (TH, n = 9), normothermia (NT, n = 9), and sham control (control, n = 5) groups. Sham animals only underwent surgical preparation. The animal model was established with 8 min of ventricular fibrillation followed by 5 min of cardiopulmonary resuscitation. Therapeutic hypothermia was induced and maintained until 24 h post-resuscitation in the TH group by surface blanket cooling, followed by rewarming at a rate of 1 °C/h for 5 h. The extravascular lung water index (ELWI), pulmonary vascular permeability index (PVPI), PO2/FiO2, and lung ultrasound score (LUS) were measured at baseline and at 1, 3, 6, 12, 24, and 30 h after resuscitation. After euthanizing the swine, their lung tissues were quickly obtained to evaluate inflammation.

RESULTS

After resuscitation, ELWI and PVPI in the NT group were higher, and PO2/FiO2 was lower, than in the sham group. However, those measures were significantly better in the TH group than the NT group. The LUS was higher in the NT group than in the sham group at 1, 3, 6, 12, 24, and 30 h after resuscitation. The LUS was significantly better in the TH group compared to the NT group. The lung tissue biopsy revealed that lung injury was more severe in the NT group than in the TH group. Increases in LUS were highly correlated with increases in ELWI (r = 0.613; p < 0.001) and PVPI (r = 0.683; p < 0.001), and decreases in PO2/FiO2 (r = - 0.468; p < 0.001).

CONCLUSIONS

Mild hypothermia protected against post-resuscitation lung injury in a swine model of cardiac arrest. Lung ultrasound was useful to dynamically evaluate the role of TH in lung protection.

Alterations in Respiratory Mechanics and Neural Respiratory Drive After Restoration of Spontaneous Circulation in a Porcine Model Subjected to Different Downtimes of Cardiac Arrest

Background

The potential alterations of respiratory pathophysiology after cardiopulmonary resuscitation (CPR) are relatively undefined. While untreated arrest is known to affect post–cardiopulmonary resuscitation circulation, whether it affects respiratory pathophysiology remains unclear. We aimed to investigate the post–cardiopulmonary resuscitation changes in respiratory mechanics and neural respiratory drive with varying delays (5 or 10 minutes) in the treatment of ventricular fibrillation (VF).

Methods and Results

Twenty‐six male Yorkshire pigs were used. Anesthetized pigs weighing 38±5 kg were randomized into 3 groups (n=10 each in the VF5 and VF10 groups, with VF kept untreated for 5 and 10 minutes, respectively, and n=6 in the sham group without VF). Defibrillation was attempted after 6 minutes of cardiopulmonary resuscitation. Pulse‐induced contour cardiac output, respiratory mechanics, diaphragmatic electromyogram, blood gas, lung imaging, and histopathology were evaluated for 12 hours. Significantly elevated mean root mean square of diaphragmatic electromyogram, transdiaphragmatic pressure, and minute ventilation were observed, but reduced minute ventilation/mean root mean square, dynamic pulmonary compliance, and Pao₂ were noted in both VF groups. Despite recovery of spontaneous breathing, the abnormalities in respiratory mechanics and neural respiratory drive, Pao₂, and extravascular lung water continued to last for >12 hours. The changes in imaging (P=0.027) and histopathology (P=0.012) were more severe in the VF10 group compared with the VF5 group.

Conclusions

There is an uncoupling between the respiratory center and ventilation after restoration of spontaneous circulation. Prolonged untreated arrest from cardiac arrest contributes to more serious alterations in lung pathophysiology.

Quantitative CT assessment of lung injury after successful cardiopulmonary resuscitation in a porcine cardiac arrest model of different downtimes

Background

Utilize quantitative computed tomography (QCT) to detect and evaluate the severity of lung injury after successful cardiopulmonary resuscitation (CPR) in a porcine cardiac arrest (CA) model with different downtimes.

Methods

Twenty-one male domestic pigs weighing 38±3 kg were randomized into 3 groups: the sham group (n=5), the ventricular fibrillation (VF) 5 min (VF5) group (n=8), and the VF 10 min (VF10) group (n=8). VF was induced and untreated for 5 (VF5 group) or 10 (VF10 group) min before the commencement of manual CPR. Eight animals (8/8, 100%) in VF5 and 6 (6/8, 75%) in VF10 were successfully resuscitated. Chest QCT scans and arterial blood gas tests were performed at baseline and 6 h post-resuscitation. The QCT score, volume, and weight of ground-glass opacification (GGO), which was defined as poorly aerated regions with a CT value ranging from -500 Hounsfield units (HU) to -100 HU, and intense parenchymal opacification (IPO), which was defined as a non-aerated area with a CT value greater than -100 HU, were quantitatively measured.

Results

Significantly shorter durations of CPR and fewer defibrillations were observed in the VF5 group compared with the VF10 group [duration of CPR: VF5 (6±0 minutes) versus VF10 (8.3±1.5 minutes), P<0.05; numbers of defibrillation: VF5 (1±0) versus VF10 (2.2±0.8), P<0.05]. Compared with the baseline or sham animals, declining gas exchanges (end-tidal CO₂, PO₂, oxygen index) were observed in both VF groups; however, there were no significant differences in gas exchanges between the VF groups. Compared with the VF5 group, the GGO QCT score, volume, and weight were significantly greater in the VF10 group (P=0.002, 0.001, and 0.002 respectively), while no significant differences were found in the IPO QCT score, volume, or weight between two the VF groups (P=0.354, 0.447, and 0.512 respectively).

Conclusions

QCT analysis enables unique non-invasive assessments of different lung injuries (IPO and GGO lesions) that can clearly distinguish heterogeneous lesions and allow for early detection and quantitative monitoring of the severity of lung injury following CPR. QCT could provide a basis for clinical early ventilation strategy management after CPR.

Cardiopulmonary Resuscitation in Infants and Children With Cardiac Disease: A Scientific Statement From the American Heart Association

Cardiac arrest occurs at a higher rate in children with heart disease than in healthy children. Pediatric basic life support and advanced life support guidelines focus on delivering high-quality resuscitation in children with normal hearts. The complexity and variability in pediatric heart disease pose unique challenges during resuscitation. A writing group appointed by the American Heart Association reviewed the literature addressing resuscitation in children with heart disease. MEDLINE and Google Scholar databases were searched from 1966 to 2015, cross-referencing pediatric heart disease with pertinent resuscitation search terms. The American College of Cardiology/American Heart Association classification of recommendations and levels of evidence for practice guidelines were used. The recommendations in this statement concur with the critical components of the 2015 American Heart Association pediatric basic life support and pediatric advanced life support guidelines and are meant to serve as a resuscitation supplement. This statement is meant for caregivers of children with heart disease in the prehospital and in-hospital settings. Understanding the anatomy and physiology of the high-risk pediatric cardiac population will promote early recognition and treatment of decompensation to prevent cardiac arrest, increase survival from cardiac arrest by providing high-quality resuscitations, and improve outcomes with postresuscitation care.

CPR feedback/prompt device improves the quality of hands-only CPR performed in manikin by laypersons following the 2015 AHA guidelines

PURPOSE

We investigated the effects of a cardiopulmonary resuscitation (CPR) feedback/prompt device on the quality of chest compression (CC) during hands-only CPR following the 2015 AHA guidelines.

METHODS

A total of 124 laypersons were randomly assigned into three groups. The first (n=42) followed the 2010 guidelines, the second (n=42) followed the 2015 guidelines with no feedback/prompt device, the third (n=40) followed the 2015 guidelines with a feedback/prompt device (2015F). Participants underwent manual CPR training and took a written basic life support examination, then required to perform 2min of hands-only CPR monitored by a CPR feedback/prompt device. The quality of CPR was quantified as the percentage of correct CCs (mean CC depth and rate, complete recoil and chest compression fraction (CCF)) per 20s, as recorded by the CPR feedback/prompt device.

RESULTS

Significantly higher correct ratios of CC, CC depth, and rate were achieved in the 2010 group in each minute vs the 2015 group. The greater mean CC depth and rate were observed in the 2015F group vs the 2015 group. The correct ratio of CC was significantly higher in the 2015F group vs the 2015 group. CCF was also significantly higher in the 2015F group vs the 2015 group in the last 20s of CPR.

CONCLUSIONS

It is difficult for a large percentage of laypersons to achieve the targets of CC depth and rate following the 2015 AHA guidelines. CPR feedback/prompt devices significantly improve the quality of hands-only CPR performance by laypersons following the standards of the 2015 AHA guidelines.

Comparison of continuous compression with regular ventilations versus 30:2 compressions-ventilations strategy during mechanical cardiopulmonary resuscitation in a porcine model of cardiac arrest

Background

A compression-ventilation (C:V) ratio of 30:2 is recommended for adult cardiopulmonary resuscitation (CPR) by the current American Heart Association (AHA) guidelines. However, continuous chest compression (CCC) is an alternative strategy for CPR that minimizes interruption especially when an advanced airway exists. In this study, we investigated the effects of 30:2 mechanical CPR when compared with CCC in combination with regular ventilation in a porcine model.

Methods

Sixteen male domestic pigs weighing 39±2 kg were utilized. Ventricular fibrillation was induced and untreated for 7 min. The animals were then randomly assigned to receive CCC combined with regular ventilation (CCC group) or 30:2 CPR (VC group). Mechanical chest compression was implemented with a miniaturized mechanical chest compressor. At the same time of beginning of precordial compression, the animals were mechanically ventilated at a rate of 10 breaths-per-minute in the CCC group or with a 30:2 C:V ratio in the VC group. Defibrillation was delivered by a single 150 J shock after 5 min of CPR. If failed to resuscitation, CPR was resumed for 2 min before the next shock. The protocol was stopped if successful resuscitation or at a total of 15 min. The resuscitated animals were observed for 72 h.

Results

Coronary perfusion pressure, end-tidal carbon dioxide and carotid blood flow in the VC group were similar to those achieved in the CCC group during CPR. No significant differences were observed in arterial blood gas parameters between two groups at baseline, VF 6 min, CPR 4 min and 30, 120 and 360 min post-resuscitation. Although extravascular lung water index of both groups significantly increased after resuscitation, no distinct difference was found between CCC and VC groups. All animals were successfully resuscitated and survived for 72 h with favorable neurologic outcomes in both groups. However, obviously more numbers of rib fracture were observed in CCC animals in comparison with VC animals.

Conclusions

There was no difference in hemodynamic efficacy and gas exchange during and after resuscitation, therefore identical 72 h survival with intact neurologic function was observed in both VC and CCC groups. However, the incidence of rib fracture increases during the mechanical CPR strategy of CCC combined with regular ventilations.

Variations of Postresuscitation Lung Function after Thrombolysis Therapy in a Cardiac Arrest Porcine Model Caused by Pulmonary Thromboembolism

BACKGROUND

Study of lung function in survivor from cardiac arrest (CA) caused by pulmonary thromboembolism (PTE) was rare. The aim of this study was to investigate the variations of postresuscitation lung function after thrombolysis treatment in a CA porcine model caused by PTE.

METHODS

After 2 min of untreated CA, pigs of 10-12 weeks with a weight of 30 ± 2 kg (n = 24) were treated with recombinant human tissue plasminogen activator (50 mg). Cardiopulmonary resuscitation (CPR) and ventilation were initiated after drug administration. Pulmonary function and arterial blood gas parameters were measured at baseline, return of spontaneous circulation (ROSC) immediately, and 1 h, 2 h, 4 h, and 6 h after ROSC.

RESULTS

The dynamic lung compliance decreased significantly at ROSC immediately and 1 h after ROSC compared to baseline (21.86 ± 2.00 vs. 26.72 ± 2.20 ml/mmHg and 20.38 ± 1.31 vs. 26.72 ± 2.20 ml/mmHg, respectively; P < 0.05; 1 mmHg = 0.133 kPa). Compared with baseline, airway resistance increased significantly at ROSC immediately and 1 h after ROSC (P < 0.05). Respiratory index also increased after ROSC and showed significant differences among baseline, ROSC immediately, and 2 h after ROSC (P < 0.05). Oxygen delivery decreased at ROSC immediately compared to baseline (P < 0.05). The oxygenation index decreased significantly at any time after ROSC compared to baseline (P < 0.05). Extravascular lung water index and pulmonary vascular permeability index (PVPI) showed significant differences at ROSC immediately compared to baseline and 1 h after ROSC (P < 0.05); PVPI at ROSC immediately was also different from 6 h after ROSC (P < 0.05). Ventilation/perfusion ratios increased after ROSC (P < 0.05). Histopathology showed fibrin effusion, bleeding in alveoli, and hemagglutination in pulmonary artery.

CONCLUSIONS

Lung function remains abnormal even after CPR with thrombolysis therapy; it is essential to continue anticoagulation and symptomatic treatment after ROSC.

Four ways to ventilate during cardiopulmonary resuscitation in a porcine model: a randomized study

Background

The optimal method for out-of-hospital ventilation during cardiopulmonary rescue (CPR) is controversial.

The aim of this study was to test different modes of ventilation during CPR for a prolonged period of 60 min.

Methods

Pigs were randomized to four groups after the induction of ventricular fibrillation, which was followed by one hour of mechanical cardiac compressions. The study comprised five pigs treated with free airways, five pigs treated with ventilators, six pigs treated with a constant oxygen flow into the tube, and six pigs treated with apnoeic oxygenation.

Results

The free airway group was tested for 1 h, but in the first 15 min, the median PaO₂ had already dropped to 5.1 kPa.

The ventilator group was tested for 1 h and still had an acceptable median PaO₂ of 10.3 kPa in the last 15 min. The group was slightly hyperventilated, with PaCO₂ at 3.8 kPa, even though the ventilator volumes were unchanged from those before induction of cardiac arrest.

In the group with constant oxygen flowing into the tube, one pig was excluded after 47 min due to blood pressure below 25 mmHg. For the remaining 5 pigs, the median PaO₂ in the last 15 min was still 14.3 kPa, and the median PaCO2 was 6.2 kPa.

The group with apnoeic oxygenation for 1 h had a resulting median PaO₂ of 10.2 kPa and a median PaCO₂ of 12.3 kPa in the last 15 min.

Discussion

Except for the free airway group, the other methods resulted in PaO₂ above 10 kPa and PaCO₂ between 3.8 and 12.3 kPa after one hour.

Conclusion

Constant oxgen flow and apnoeic oxygenation seemed to be useable alternatives to ventilator treatment.

Ventilation and gas exchange management after cardiac arrest

For several decades, physicians had integrated several interventions aiming to improve the outcomes in post-cardiac arrest patients. However, the mortality rate after cardiac arrest is still as high as 50%. Post-cardiac arrest syndrome is associated with high morbidity and mortality due to not only poor neurological outcome and cardiovascular failure but also respiratory dysfunction. To minimize ventilator-associated lung injury, protective mechanical ventilation by using low tidal volume ventilation and driving pressure may decrease pulmonary complications and improve survival. Low level of positive end-expiratory pressure (PEEP) can be initiated and titrated with careful cardiac output and respiratory mechanics monitoring. Furthermore, optimizing gas exchange by avoiding hypoxia and hyperoxia as well as maintaining normocarbia may improve neurological and survival outcome. Early multidisciplinary cardiac rehabilitation intervention is recommended. Minimally invasive monitoring techniques, that is, echocardiography, transpulmonary thermodilution method measuring extravascular lung water, as well as transcranial Doppler ultrasound, might be useful to improve appropriate management of post-cardiac arrest patients.

Should unobstructed gasping be facilitated and confirmed before administering adrenaline, otherwise, give titrated vasopressin?

A recent commentary, "Resuscitation That's (Un)Shockable: Time to Get the Adrenaline Flowing", published in the New England Journal of Medicine Journal Watch called attention to a relatively recent study showing that a large and increasing percentage of patients with in-hospital cardiac arrests exhibit initial nonshockable rhythms (asystole or pulseless electrical activity [PEA]; 82% in 2009 vs 69% in 2000) and a most recent study that concluded that neurologically intact survival to hospital discharge after in-hospital cardiac arrest was significantly more likely after earlier epinephrine administration. It was found that delayed administration of epinephrine was associated significantly with lower chance for survival to hospital discharge, in stepwise fashion (12%, 10%, 8%, and 7% survival, respectively, for patients receiving their first epinephrine dose≤3, 4-6, 7-9, and >9 minutes after arrest). Although early use of epinephrine to manage patients with nonshockable rhythms lacks strong evidence to support efficacy, focus on time to epinephrine administration-in addition to high-quality chest compressions-might be the best early intervention. However, evidence may strongly support the recommendation that adrenaline needs to be used very early because without effective-depth cardiopulmonary resuscitation (CPR) with complete recoil, epinephrine may only be effective when gasping is present, which is a time-limited phenomenon. However, because very few rescuers can perform effective-depth chest compressions with complete recoil, gasping is critically necessary for adequate ventilation and generation of adequate coronary and cerebral perfusion. However, under acidemic conditions and high catecholamine levels and/or absence of gasping, vasopressin should be administered instead.

Ventilation/perfusion ratios measured by multiple inert gas elimination during experimental cardiopulmonary resuscitation

BACKGROUND

During cardiopulmonary resuscitation (CPR) the ventilation/perfusion distribution (VA /Q) within the lung is difficult to assess. This experimental study examines the capability of multiple inert gas elimination (MIGET) to determine VA /Q under CPR conditions in a pig model.

METHODS

Twenty-one anaesthetised pigs were randomised to three fractions of inspired oxygen (1.0, 0.7 or 0.21). VA/ Q by micropore membrane inlet mass spectrometry-derived MIGET was determined at baseline and during CPR following induction of ventricular fibrillation. Haemodynamics, blood gases, ventilation distribution by electrical impedance tomography and return of spontaneous circulation were assessed. Intergroup differences were analysed by non-parametric testing.

RESULTS

MIGET measurements were feasible in all animals with an excellent correlation of measured and predicted arterial oxygen partial pressure (R(2)  = 0.96, n = 21 for baseline; R(2)  = 0.82, n = 21 for CPR). CPR induces a significant shift from normal VA /Q ratios to the high VA /Q range. Electrical impedance tomography indicates a dorsal to ventral shift of the ventilation distribution. Diverging pulmonary shunt fractions induced by the three inspired oxygen levels considerably increased during CPR and were traceable by MIGET, while 100% oxygen most negatively influenced the VA /Q. Return of spontaneous circulation were achieved in 52% of the animals.

CONCLUSIONS

VA /Q assessment by MIGET is feasible during CPR and provides a novel tool for experimental purposes. Changes in VA /Q caused by different oxygen fractions are traceable during CPR. Beyond pulmonary perfusion deficits, these data imply an influence of the inspired oxygen level on VA /Q. Higher oxygen levels significantly increase shunt fractions and impair the normal VA /Q ratio.

Effect of continuous compression and 30:2 cardiopulmonary resuscitation on cerebral microcirculation in a porcine model of cardiac arrest

BACKGROUND

The effect of rescue breathing on neurologic prognosis after cardiopulmonary resuscitation (CPR) is controversial. Therefore, we investigated the cerebral microcirculatory and oxygen metabolism during continuous compression (CC) and 30:2 CPR (VC) in a porcine model of cardiac arrest to determine which is better for neurologic prognosis after CPR.

METHODS

After 4 min of ventricular fibrillation, 20 pigs were randomised into two groups (n=10/group) receiving CC-CPR or VC-CPR. Cerebral oxygen metabolism and blood flow were measured continuously using laser Doppler flowmetry. Haemodynamic data were recorded at baseline and 5 min, 30 min, 2 h and 4 h after restoration of spontaneous circulation (ROSC).

RESULTS

Compared with the VC group, the mean cortical cerebral blood flow was significantly higher at 5 min ROSC in the CC group (P<0.05), but the difference disappeared after that time point. Brain percutaneous oxygen partial pressures were higher, and brain percutaneous carbon dioxide partial pressures were lower, in the VC group from 30 min to 4 h after ROSC; significant differences were found between the two groups (P<0.05). However, no significant difference of the cerebral oxygen extraction fraction existed between the two groups.

CONCLUSIONS

Inconsistency of systemic circulation and cerebral microcirculation with regard to blood perfusion and oxygen metabolism is common after CPR. No significant differences in cortical blood flow and oxygen metabolism were found between the CC-CPR and VC-CPR groups after ROSC.