Cerebral perfusion and metabolism with mild hypercapnia vs. normocapnia in a porcine post cardiac arrest model with and without targeted temperature management

Aim

To determine whether targeting mild hypercapnia (PaCO2 7 kPa) would yield improved cerebral blood flow and metabolism compared to normocapnia (PaCO2 5 kPa) with and without targeted temperature management to 33 °C (TTM33) in a porcine post-cardiac arrest model.

Methods

39 pigs were resuscitated after 10 minutes of cardiac arrest using cardiopulmonary bypass and randomised to TTM33 or no-TTM, and hypercapnia or normocapnia. TTM33 was managed with intravasal cooling. Animals were stabilized for 30 minutes followed by a two-hour intervention period. Hemodynamic parameters were measured continuously, and neuromonitoring included intracranial pressure (ICP), pressure reactivity index, cerebral blood flow, brain-tissue pCO2 and microdialysis. Measurements are reported as proportion of baseline, and areas under the curve during the 120 min intervention period were compared.

Results

Hypercapnia increased cerebral flow in both TTM33 and no-TTM groups, but also increased ICP (199% vs. 183% of baseline, p = 0.018) and reduced cerebral perfusion pressure (70% vs. 84% of baseline, p < 0.001) in no-TTM animals. Cerebral lactate (196% vs. 297% of baseline, p < 0.001), pyruvate (118% vs. 152% of baseline, p < 0.001), glycerol and lactate/pyruvate ratios were lower with hypercapnia in the TTM33 group, but only pyruvate (133% vs. 150% of baseline, p = 0.002) was lower with hypercapnia among no-TTM animals.

Conclusion

In this porcine post-arrest model, hypercapnia led to increased cerebral flow both with and without hypothermia, but also increased ICP and reduced cerebral perfusion pressure in no-TTM animals. The effects of hypercapnia were different with and without TTM.(Institutional protocol number: FOTS, id 14931).

Lung tissue injury and hemodynamic effects of ventilations synchronized or unsynchronized to continuous chest compressions in a porcine cardiac arrest model

Aim

Compare lung injury and hemodynamic effects in synchronized ventilations (between two chest compressions) vs. unsynchronized ventilations during cardiopulmonary resuscitation (CPR) in a porcine model of cardiac arrest.

Methods

Twenty pigs were randomized to either synchronized or unsynchronized group. Ventricular fibrillation was induced electrically and left for 1.5 minutes. Four minutes of basic chest compression:ventilation (30:2) CPR was followed by eight minutes of either synchronized or unsynchronized ventilations (10/min) during continuous compressions before defibrillation was attempted. Aortic, right atrial and intracerebral pressures, carotid and cerebral blood flow and cardiac output were measured. Airway monitoring included capnography and respiratory function monitor. Macro- and microscopic lung injuries were assessed post-mortem.

Results

There were no significant differences between groups in any of the measured hemodynamic variables or inspiration time (0.4 vs. 1.0 s, p = 0.05). The synchronized ventilation group had lower median peak inspiratory airway pressure (57 vs. 94 cm H2O, p < 0.001), lower minute ventilation (3.7 vs. 9.4 l min-1, p < 0.001), lower pH (7.31 vs. 7.53, p < 0.001), higher pCO2 (5.2 vs. 2.5 kPa, p < 0.001) and lower pO2 (31.6 vs. 54.7 kPa, p < 0.001) compared to the unsynchronized group after 12 minutes of CPR. There was significant lung injury after CPR in both synchronized and unsynchronized groups.

Conclusion

Synchronized and unsynchronized ventilations resulted in similar hemodynamics and lung injury during continuous mechanical compressions of pigs in cardiac arrest. Animals that received unsynchronized ventilations with one second inspiration time at a rate of ten ventilations per minute were hyperventilated and hyperoxygenated.Institutional protocol number: FOTS, id 6948.

Cerebral perfusion and metabolism with mean arterial pressure 90 vs. 60 mmHg in a porcine post cardiac arrest model with and without targeted temperature management

AIM

To determine whether targeting a mean arterial pressure of 90 mmHg (MAP90) would yield improved cerebral blood flow and less ischaemia compared to MAP 60 mmHg (MAP60) with and without targeted temperature management at 33 °C (TTM33) in a porcine post-cardiac arrest model.

METHODS

After 10 min of cardiac arrest, 41 swine of either sex were resuscitated until return of spontaneous circulation (ROSC). They were randomised to TTM33 or no-TTM, and MAP60 or MAP90; yielding four groups. Temperatures were managed with intravasal cooling and blood pressure targets with noradrenaline, vasopressin and nitroprusside, as appropriate. After 30 min of stabilisation, animals were observed for two hours. Cerebral perfusion pressure (CPP), cerebral blood flow (CBF), pressure reactivity index (PRx), brain tissue pCO2 (PbtCO2) and tissue intermediary metabolites were measured continuously and compared using mixed models.

RESULTS

Animals randomised to MAP90 had higher CPP (p < 0.001 for both no-TTM and TTM33) and CBF (no-TTM, p < 0.03; TH, p < 0.001) compared to MAP60 during the 150 min observational period post-ROSC. We also observed higher lactate and pyruvate in MAP60 irrespective of temperature, but no significant differences in PbtCO2 and lactate/pyruvate-ratio. We found lower PRx (indicating more intact autoregulation) in MAP90 vs. MAP60 (no-TTM, p = 0.04; TTM33, p = 0.03).

CONCLUSION

In this porcine cardiac arrest model, targeting MAP90 led to better cerebral perfusion and more intact autoregulation, but without clear differences in ischaemic markers, compared to MAP60.

INSTITUTIONAL PROTOCOL NUMBER

FOTS, id 8442.

Suboptimal heart rate assessment and airway management in infants receiving delivery room chest compressions: a quality assurance project

OBJECTIVE

In a previous audit, we demonstrated poor compliance with the neonatal resuscitation algorithm. Training can improve guideline compliance and performance. We aimed to prospectively collect detailed data on delivery room resuscitations to identify needs for educational interventions.

DESIGN

Observational study using video recordings of neonatal resuscitations. We analysed episodes where chest compressions (CCs) were provided.

SETTING

A Norwegian university hospital.

PATIENTS

All delivery room resuscitations August 2014 to November 2016.

INTERVENTIONS

The recordings were transcribed using Interact V.9 software (Mangold Int GmbH, Arnstorf, Germany). Supplementary information was collected from the patient electronic records.

MAIN OUTCOME MEASURES

Heart rate (HR) assessment, provision of positive pressure ventilation (PPV) and CC, endotracheal intubation and team communication.

RESULTS

Twenty-nine CC episodes were analysed. We identified team discordance in the decisions to perform CC and only 6 (21%) were retrospectively judged to be in need for CC: 8 (28%) infants had adequate spontaneous respiration, 18 (62%) infants received ineffective PPV and 5 (17%) had a HR >60 bpm. Only one infant was intubated before CC, and we could not identify a consistent pattern of ventilation corrective actions. One infant received CC without prior HR assessment. In some infants, CC duration was exceedingly short, and 11 (38%) of the infants that received CC were not admitted to the NICU. Six (21%) infants had no documentation of CPR in the delivery record.

CONCLUSIONS

Education and training should focus on team function and communication, correct and timely HR assessment, effective PPV, and indications for endotracheal intubation.

Video performance-debriefings and ventilation-refreshers improve quality of neonatal resuscitation

AIM

Providers caring for newly born infants require skills and knowledge to initiate prompt and effective positive pressure ventilation (PPV) if the newborn does not breathe spontaneously after birth. We hypothesized implementation of high frequency/short duration deliberate practice training and post event video-based debriefings would improve process of care and decreases time to effective spontaneous respiration.

METHODS

Pre- and post-interventional quality study performed at two Norwegian university hospitals. All newborns receiving PPV were prospectively video-recorded, and initial performance data guided the development of educational interventions. A priori primary outcome was changed from process of care using the Neonatal Resuscitation Performance Evaluation (NRPE) score to time to effective spontaneous respiration as the NRPE score could only be obtained from one site due to lack of staff resources.

RESULTS

Over 12 months, 297 PPV-Refreshers and 52 performance debriefings were completed with 227 unique providers attending a PPV-Refresher and 93 unique providers completed a debriefing. We compared 102 PPV-events pre- to 160 PPV-events post-bundle implementation. The time to effective spontaneous respiration decreased from median (95% confidence interval) 196 (140-237) to 144 (120-163) s, p = 0.010. The NRPE-score increased significantly from median 77% (75-81) pre- to 89% (86-92) post-implementation, p < 0.001. There were no significant differences in time to heart rate >100 beats/min or number of newborns transferred to intensive care.

CONCLUSION

High frequency/short duration deliberate practice PPV psychomotor training combined with performance-focused team debriefings using video recordings of actual resuscitations may improve time to effective spontaneous breathing and adherence to guidelines during real neonatal resuscitations.

Implementation and effectiveness of a video-based debriefing programme for neonatal resuscitation

BACKGROUND

Approximately 5%-10% of newly born babies need intervention to assist transition from intra- to extrauterine life. All providers in the delivery ward are trained in neonatal resuscitation, but without clinical experience or exposure, training competency is transient with a decline in skills within a few months. The aim of this study was to evaluate whether neonatal resuscitations skills and team performance would improve after implementation of video-assisted, performance-focused debriefings.

METHODS

We installed motion-activated video cameras in every resuscitation bay capturing consecutive compromised neonates. The videos were used in debriefings led by two experienced facilitators, focusing on guideline adherence and non-technical skills. A modification of Neonatal Resuscitation Performance Evaluation (NRPE) was used to score team performance and procedural skills during a 7 month study period (2.5, 2.5 and 2 months pre-, peri- and post-implementation) (median score with 95% confidence interval).

RESULTS

We compared 74 resuscitation events pre-implementation to 45 events post-implementation. NRPE-score improved from 77% (75, 81) to 89% (86, 93), P < 0.001. Specifically, the sub-categories "group function/communication", "preparation and initial steps", and "positive pressure ventilation" improved (P < 0.005). Adequate positive pressure ventilation improved from 43% to 64% (P = 0.03), and pauses during initial ventilation decreased from 20% to 0% (P = 0.02). Proportion of infants with heart rate > 100 bpm at 2 min improved from 71% pre- vs. 82% (P = 0.22) post-implementation.

CONCLUSION

Implementation of video-assisted, performance-focused debriefings improved adherence to best practice guidelines for neonatal resuscitation skill and team performance.

Incidence and characteristics of positive pressure ventilation delivered to newborns in a US tertiary academic hospital

INTRODUCTION

The Neonatal Resuscitation Program (NRP) guidelines recommend positive pressure ventilation (PPV) in the first 60s of life to support perinatal transition in non-breathing newborns. Our aim was to describe the incidence and characteristics of newborn PPV using real-time observation in the delivery unit.

METHODS

Prospective, observational, quality improvement study conducted at a tertiary academic hospital. Deliveries during randomized weekday/evening 8-h shifts were attended by a trained observer. Intervention data were recorded for all newborns with gestational age (GA) ≥34wks that received PPV. Descriptive summaries and Kruskal-Wallis test for continuous variables and Fisher's exact test for categorical variables were used to compare characteristics.

RESULTS

Of 1135 live deliveries directly observed over 18mos, 64 (6%) newborns with a mean GA 39±2wks received PPV: Median time from birth to warmer was 20s (IQR 15-22s); PPV was initiated within 60s of life in 29 (45%) and between 60 and 90s of life in 17 (27%). PPV duration was <120s in 38 (60%). Seven/21 (33%) newborns that received PPV after vaginal delivery were not pre-identified and resuscitation team was alerted after delivery. We found no association between PPV start time and duration of PPV (p=0.86).

CONCLUSION

We observed that most (94%) term newborns spontaneously initiate respirations. In over half observed deliveries receiving PPV, time to initiation of PPV was greater than 60s (longer than recommended). Compliance with current NRP guidelines is difficult, and it's not clear whether it is the recommendations or the training to achieve PPV recommendations that should be modified.

Targeted simulation and education to improve cardiac arrest recognition and telephone assisted CPR in an emergency medical communication centre

AIM

Recognition of cardiac arrest and prompt activation time by emergency medical dispatch are key process measures that have been associated with improved survival after out-of-hospital cardiac arrest (OHCA). The aim of this study is to improve recognition of OHCA and time to initiation of telephone assisted chest compressions in an emergency medical communication centre (EMCC).

METHODS

A prospective, interventional study implementing targeted interventions in an EMCC. Interventions included: (1) lectures focusing on agonal breathing and interrogation strategy (2) simulation training (3) structured dispatcher feedback (4) web-based telephone assisted CPR training program. All ambulance-confirmed OHCA calls in the study period were assessed and relevant process and result measures were recorded pre- and post-intervention. Cardiac arrest was reported as (1) recognised, (2) not recognised or (3) delayed recognition.

RESULTS

We included 331 and 230 calls pre- and post-intervention, respectively. Recognition of cardiac arrest improved significantly after intervention (89 vs. 95%, p=0.024). Delayed recognition was significantly reduced (21 vs. 6%, p>0.001), as was misinterpretation of agonal breathing (25 vs. 10%, p<0.001). Telephone assisted compressions increased (71% vs. 83%, p=0.002) whereas bystander performed ventilations decreased after intervention (23% vs. 15%, p=0.016). Time intervals for initiation of chest compression instructions (2.6 vs. 2.3min, p=0.042) and delivery of telephone assisted chest compressions (3.3 vs. 2.8min, p=0.015) were significantly shortened after intervention.

CONCLUSION

Targeted simulation, education and feedback significantly improved recognition of OHCA and reduced time to first chest compression. Continuous measurement of key quality metrics can facilitate development of targeted education and training.

Ventilation fraction during the first 30s of neonatal resuscitation

AIM

Approximately 5% of newborns receive positive pressure ventilation (PPV) for successful transition. Guidelines urge providers to ensure effective PPV for 30-60s before considering chest compressions and intravenous therapy. Pauses in this initial PPV may delay recovery of spontaneous respiration. The aim was to find the ventilation fraction during the first 30s of PPV in non-breathing babies.

METHODS

Prospective observational study in two hospitals in Norway. All newborns receiving PPV immediately after delivery were included. Cameras with motion detectors were installed at every resuscitation bay capturing both expected and unexpected compromised newborns. We determined the cumulative number of seconds with PPV efforts excluding pauses in infants without spontaneous breathing and reported ventilation fraction during the first minute. Data are presented as median (IQR).

RESULTS

110 of 3508 (3%) newborns received PPV and were filmed in the resuscitation bays. PPV started 42 (18-78)s after arrival at the resuscitation bay and median duration was 100 (35-225)s. Forty-eight infants (44%) were ventilated continuously, or with minimal pause (ventilation fraction >90%) during the first 30s of PPV. For the remaining 62 infants ventilation fraction was 60% (39-75). PPV was interrupted due to adjustments, checking heart rate, stimulation, administration of CPAP and suctioning.

CONCLUSION

In 56% of the neonatal resuscitations interruptions in ventilation are frequent with 60% ventilation fraction during the first 30s of PPV. Eliminating disruption for improved quality of PPV delivery should be emphasized when training newborn resuscitation providers.

Incidence of Newborn Stabilization and Resuscitation Measures and Guideline Compliance during the First Minutes of Life in Norway

BACKGROUND

Most newborns manage the transition from intra- to extrauterine life without interventions, yet neonatal morbidity caused by failure of transition remains an important health problem.

OBJECTIVE

To determine the incidence of neonatal stabilization and resuscitation measures and guideline compliance during the first minutes after birth.

METHODS

This is a prospective, observational study of all births in three Norwegian hospitals. All interventions performed, including suctioning, use of pulse oximetry, continuous positive airway pressure (CPAP), positive pressure ventilation (PPV), supplemental oxygen, intubation, and administration of drugs, were registered at every on-call team shift during the study period.

RESULTS

A total of 1,507 live-born infants were included, of whom 264 (18%) were brought to the resuscitation crib. Oropharyngeal suctioning was performed in 77 (5%), deep blind suctioning was carried out in 10 (1%) and 84 (6%) were monitored using pulse oximetry. PPV was provided in 58 cases (4%) - 8 (21%) of <34 weeks and 50 (3%) of ≥34 weeks of gestation. Sustained inflation is not routinely used in these departments. CPAP (without PPV) was provided in 17 cases (1%) - 4 (0.3%) were intubated and ventilated through the endotracheal tube. Supplemental oxygen was given to 39 infants (3%) - 9 without pulse oximetry monitoring. The median (interquartile range) birth weight and gestational age of the newborns requiring PPV and/or CPAP were 3,220 g (2,643-3,858) and 39 weeks (37-41), respectively.

CONCLUSION

In this study, the need for resuscitation and/or stabilization measures was commonly considered, and 4% of all newborns received PPV. Despite strong guideline emphasis on the use of pulse oximetry to guide oxygen administration, many infants received oxygen treatment without pulse oximetry monitoring.