Medications in neonatal resuscitation: epinephrine and the search for better alternative strategies

Inadequate Bioavailability of Intramuscular Epinephrine in a Neonatal Asphyxia Model

BACKGROUND

Over half a million newborn deaths are attributed to intrapartum related events annually, the majority of which occur in low resource settings. While progress has been made in reducing the burden of asphyxia, novel approaches may need to be considered to further decrease rates of newborn mortality. Administration of intravenous, intraosseous or endotracheal epinephrine is recommended by the Newborn Resuscitation Program (NRP) with sustained bradycardia at birth. However, delivery by these routes requires both advanced skills and specialized equipment. Intramuscular (IM) epinephrine may represent a simple, low cost and highly accessible alternative for consideration in the care of infants compromised at birth. At present, the bioavailability of IM epinephrine in asphyxia remains unclear.

METHODS

Four term fetal lambs were delivered by cesarean section and asphyxiated by umbilical cord occlusion with resuscitation after 5 min of asystole. IM epinephrine (0.1 mg/kg) was administered intradeltoid after 1 min of positive pressure ventilation with 30 s of chest compressions. Serial blood samples were obtained for determination of plasma epinephrine concentrations by ELISA.

RESULTS

Epinephrine concentrations failed to increase following administration via IM injection. Delayed absorption was observed after return of spontaneous circulation (ROSC) in half of the studies.

CONCLUSIONS

Inadequate absorption of epinephrine occurs with IM administration during asphyxial cardiac arrest, implying this route would be ineffective in infants who are severely compromised at birth. Late absorption following ROSC raises concerns for risks of side effects. However, the bioavailability and efficacy of intramuscular epinephrine in less profound asphyxia may warrant further evaluation.

Drugs in the delivery room

The need for cardiopulmonary resuscitation in newborns is quite rare, as most non-vigorous infants respond well to effective ventilation. For the minority of babies who do not respond to adequate ventilation, chest compressions are necessary using the preferred two thumb technique. Since effective ventilation remains a key component to successful resuscitation, chest compressions are coordinated with ventilations in a 3:1 ratio. If despite adequate ventilation and compressions, the heart rate remains below 60 beats per minute, epinephrine is indicated. The intravenous route is preferred over the endotracheal route and the recommended dose of epinephrine is 0.01-0.03 mg/kg. This can be repeated every 3-5 min until return of spontaneous circulation is achieved. In rare instances, when there is no response to these above measures and in infants who show evidence of significant hypovolemia, volume replacement should be considered.

Volume Versus Mass Dosing of Epinephrine for Neonatal Resuscitation: A Randomized Trial

BACKGROUND

Intravenous epinephrine for neonatal resuscitation requires weight-based calculations. Epinephrine is available in 2 different concentrations, increasing the risk of dosing errors. Expert panels have conflicting recommendations for the ordering method. The Neonatal Resuscitation Program recommends the volume (milliliters per kilogram) method, whereas the Institute for Safe Medication Practices recommends the mass (milligrams per kilogram) method. In this study, we aim to determine if the mass method is more accurate and efficient than the volume method.

METHODS

In a randomized crossover simulation study, 70 NICU and pediatric emergency department nurses calculated the intended dose then prepared epinephrine using both the mass and volume methods. Both epinephrine concentrations were available. Scenarios were video recorded and timed. The primary outcome was the proportion of epinephrine doses prepared correctly. Variables associated with correct dosing were analyzed by using logistic regression.

RESULTS

Of 136 total doses, 77 (57%) were prepared correctly. The correct intended dose was calculated more frequently by using the mass method (82% vs 68%; risk difference 15%; 95% confidence interval 3% to 26%), but there was no difference in the proportion of doses that were actually prepared correctly (53% of mass method doses versus 60% of volume method doses; risk difference -7%; 95% confidence interval -24% to 9%). There was no difference between methods in the time required to prepare the dose. Selecting the correct epinephrine concentration was the only variable associated with correct dosing.

CONCLUSIONS

The mass method was neither more accurate nor more efficient. Nurses made frequent errors when using both methods. This is a serious patient safety risk. Additional educational and medication safety interventions are urgently needed.

Bioavailability of endotracheal epinephrine in an ovine model of neonatal resuscitation

BACKGROUND

Distressed infants in the delivery room and those that have completed postnatal transition are both resuscitated according to established neonatal resuscitation guidelines, often with endotracheal (ET) epinephrine at the same dose. We hypothesized that ET epinephrine would have higher bioavailability in a post-transitional compared to transitioning newborn model due to absence of fetal lung liquid and intra-cardiac shunts.

METHODS

15 term fetal (transitioning newborn) and 6 postnatal lambs were asphyxiated by umbilical cord and ET tube occlusion respectively. Lambs were resuscitated after 5 min of asystole. ET epinephrine (0.1 mg/kg) was administered after 1 min of positive pressure ventilation (PPV) and chest compressions, and repeated 3 min later, followed by intravenous (IV) epinephrine (0.03 mg/kg) every 3 min until return of spontaneous circulation (ROSC). Serial plasma epinephrine concentrations were measured.

RESULTS

Peak plasma epinephrine concentrations were lower in transitioning newborns as compared to postnatal lambs: after a single ET dose (145.36 ± 135.5 ng/ml vs 553.54 ± 215 ng/ml, p < 0.01) and after two ET doses (443 ± 192.49 ng/ml vs 1406 ± 420.8 ng/ml, p < 0.01). The rates of ROSC with a single ET dose were similar in both groups (40% vs 50% in newborn and postnatal respectively, p > 0.99). There was a higher incidence of post-ROSC tachycardia and increased carotid blood flow in the postnatal group.

CONCLUSIONS

In the postnatal period, ET epinephrine at currently recommended doses resulted in higher peak epinephrine concentrations, post-ROSC tachycardia and cerebral reperfusion without significant differences in incidence of ROSC. Further studies evaluating the optimal dose of ET epinephrine during the postnatal period are warranted.

Current Challenges in Neonatal Resuscitation: What is the Role of Adrenaline?

Adrenaline, also known as epinephrine, is a hormone, neurotransmitter, and medication. It is the best established drug in neonatal resuscitation, but only weak evidence supports current recommendations for its use. Furthermore, the available evidence is partly based on extrapolations from adult studies, and this introduces further uncertainty, especially when considering the unique physiological characteristics of newly born infants. The timing, dose, and route of administration of adrenaline are still debated, even though this medication has been used in neonatal resuscitation for a long time. According to the most recent Neonatal Resuscitation Guidelines from the American Heart Association, adrenaline use is indicated when the heart rate remains < 60 beats per minute despite the establishment of adequate ventilation with 100% oxygen and chest compressions. The aforementioned guidelines recommend intravenous administration (via an umbilical venous catheter) of adrenaline at a dose of 0.01-0.03 mg/kg (1:10,000 concentration). Endotracheal administration of a higher dose (0.05-0.1 mg/kg) may be considered while venous access is being obtained, even if supportive data for endotracheal adrenaline are lacking. The safety and efficacy of intraosseous administration of adrenaline remain to be investigated. This article reviews the evidence on the circulatory effects and tolerability of adrenaline in the newborn, discusses literature data on adrenaline use in neonatal cardiopulmonary resuscitation, and describes international recommendations and outcome data regarding the use of this medication during neonatal resuscitation.

What to do if A + B doesn't work

The majority of newborn resuscitations require very little beyond simple airway management and assisted ventilation. If cardiovascular collapse is serious enough to warrant additional support, resuscitation algorithms recommend moving to chest compressions and then on to medications and possibly volume replacement if vital signs remain marginal or absent. The evidence base upon which this part of the neonatal resuscitation algorithm is structured is sparse. Chest compressions and medications are rare interventions that do not lend themselves easily to clinical trials. Slowly but surely, however, the genesis of an empirical evidence base for this part of the algorithm is beginning to appear.

Review of Routes to Administer Medication During Prolonged Neonatal Resuscitation

OBJECTIVE

During neonatal cardiopulmonary resuscitation, early establishment of vascular access is crucial. We aimed to review current evidence regarding different routes for the administration of medications during neonatal resuscitation.

DATA SOURCES

We reviewed PubMed, EMBASE, and Google Scholar using MeSH terms "catheterization," "umbilical cord," "delivery room," "catecholamine," "resuscitation," "simulation," "newborn," "infant," "intraosseous," "umbilical vein catheter," "access," "intubation," and "endotracheal."

STUDY SELECTION

Articles in all languages were included. Initially, we aimed to identify only neonatal studies and limited the search to randomized controlled trials.

DATA EXTRACTION

Due to a lack of available studies, studies in children and adults, as well as animal studies and also nonrandomized studies were included.

DATA SYNTHESIS

No randomized controlled trials comparing intraosseous access versus peripheral intravascular access versus umbilical venous catheter versus endotracheal tube versus laryngeal mask airway or any combination of these during neonatal resuscitation in the delivery room were identified. Endotracheal tube: endotracheal tube epinephrine administration should be limited to situations were no vascular access can be established. Laryngeal mask airway: animal studies suggest that a higher dose of epinephrine for endotracheal tube and laryngeal mask airway is required compared with IV administration, potentially increasing side effects. Umbilical venous catheter: European resuscitation guidelines propose the placement of a centrally positioned umbilical venous catheter during neonatal cardiopulmonary resuscitation; intraosseous access: case series reported successful and quick intraosseous access placement in newborn infants. Peripheral intravascular access: median time for peripheral intravascular access insertion was 4-5 minutes in previous studies.

CONCLUSIONS

Based on animal studies, endotracheal tube administration of medications requires a higher dose than that by peripheral intravascular access or umbilical venous catheter. Epinephrine via laryngeal mask airway is feasible as a noninvasive alternative approach for drug delivery. Intraosseous access should be considered in situations with difficulty in establishing other access. Randomized controlled clinical trials in neonates are required to compare all access possibilities described above.

Effects of epinephrine on hemodynamic changes during cardiopulmonary resuscitation in a neonatal piglet model

BackgroundAsphyxia is the most common reason for newborns to fail to make a successful fetal-to-neonatal transition. There is currently a lack of data evaluating hemodynamic effects of epinephrine during neonatal cardiopulmonary resuscitation.MethodsTwenty-four newborn piglets were exposed to asphyxia. Thereafter, positive pressure ventilation was commenced for 30 s, followed by chest compressions (CC). Piglets were randomized into three experimental groups: 3:1 compression:ventilation ratio; CC during sustained inflation (SI) at a rate of 90 CC per minute, or CC during SI at a rate of 120 CC per minute. Epinephrine (0.01 mg/kg per dose) was administered to a maximum of four doses. Hemodynamic parameters were measured throughout the experiment.ResultsAnimals were divided into survivors and nonsurvivors. End-diastolic and developed pressures declined after epinephrine administration in the survivor group. dp/dt min was significantly higher in the survivor group whereas dp/dt max showed no significant differences. Epinephrine had no effect on either heart rate or cardiac output in both groups. Ejection fraction increased after epinephrine with no significant difference between groups.ConclusionEpinephrine did not affect survival rates or return of spontaneous circulation in our postnatal porcine model of neonatal asphyxia.

Epinephrine Use during Newborn Resuscitation

Epinephrine use in the delivery room for resuscitation of the newborn is associated with significant morbidity and mortality. Evidence for optimal dose, timing, and route of administration of epinephrine during neonatal resuscitation comes largely from extrapolated adult or animal literature. In this review, we provide the current recommendations for use of epinephrine during neonatal resuscitation and also the evidence behind these recommendations. In addition, we review the current proposed mechanism of action of epinephrine during neonatal resuscitation, review its adverse effects, and identify gaps in knowledge requiring urgent research.

Hemodynamics and gas exchange during chest compressions in neonatal resuscitation

PURPOSE

Current knowledge about pulmonary/systemic hemodynamics and gas exchange during neonatal resuscitation in a model of transitioning fetal circulation with fetal shunts and fluid-filled alveoli is limited. Using a fetal lamb asphyxia model, we sought to determine whether hemodynamic or gas-exchange parameters predicted successful return of spontaneous circulation (ROSC).

METHODS

The umbilical cord was occluded in 22 lambs to induce asphyxial cardiac arrest. Following five minutes of asystole, resuscitation as per AHA-Neonatal Resuscitation Program guidelines was initiated. Hemodynamic parameters and serial arterial blood gases were assessed during resuscitation.

RESULTS

ROSC occurred in 18 lambs (82%) at a median (IQR) time of 120 (105-180) seconds. There were no differences in hemodynamic parameters at baseline and at any given time point during resuscitation between the lambs that achieved ROSC and those that did not. Blood gases at arrest prior to resuscitation were comparable between groups. However, lambs that achieved ROSC had lower PaO2, higher PaCO2, and lower lactate during resuscitation. Increase in diastolic blood pressures induced by epinephrine in lambs that achieved ROSC (11 ±4 mmHg) did not differ from those that were not resuscitated (10 ±6 mmHg). Low diastolic blood pressures were adequate to achieve ROSC.

CONCLUSIONS

Hemodynamic parameters in a neonatal lamb asphyxia model with transitioning circulation did not predict success of ROSC. Lactic acidosis, higher PaO2 and lower PaCO2 observed in the lambs that did not achieve ROSC may represent a state of inadequate tissue perfusion and/or mitochondrial dysfunction.

Characteristics and outcomes of very low birth weight infants receiving epinephrine during delivery room resuscitation

BACKGROUND

Delivery room resuscitation of very low birth weight infants can involve use of endotracheal or intravenous epinephrine. Data of the past 19 years were reviewed to identify the usage of epinephrine in delivery room and identify characteristics of these babies.

METHODS

Neonates with ≤1500g birthweight from January 1996 to August 2014 were reviewed. Infants born alive and admitted to NICU were eligible. Characteristics such as demographics, survival and outcomes were recorded. Variables significant at p≤0.1 among neonates receiving epinephrine were further analyzed via multiple logistic regressions.

RESULTS

Out of 5868 eligible neonates, 416 (7%) received epinephrine in the delivery room. The infants who received epinephrine were of lower estimated gestational age (25 vs. 28wk) and lower birth weight (746 vs. 980g). Gender, race and mode of delivery were comparable between the two cohorts. Survival was higher in non-epinephrine group (89.4 vs. 61.1%). Bacterial infection (24.3 vs. 18.4%) and combined grade 3 and 4 intraventricular hemorrhage (18.4 vs. 8.4%) were higher in epinephrine group. Use of epinephrine in the delivery room was associated with decreased survival even after controlling for birth weight, gestational age and low Apgar scores [Odd ratio - 0.48 with 95% CI (0.37-0.62), p<0.001].

CONCLUSION

Neonates with lower birth weight and younger gestational age were more likely to receive epinephrine during resuscitation at birth. Use of epinephrine in delivery room was associated with lower survival and severe intraventricular hemorrhage among very low birth weight infants.

Evaluation of Timing and Route of Epinephrine in a Neonatal Model of Asphyxial Arrest

Background

Epinephrine administered by low umbilical venous catheter (UVC) or endotracheal tube (ETT) is indicated in neonates who fail to respond to positive pressure ventilation and chest compressions at birth. Pharmacokinetics of ETT epinephrine via fluid‐filled lungs or UVC epinephrine in the presence of fetal shunts is unknown. We hypothesized that epinephrine administered by ETT or low UVC results in plasma epinephrine concentrations and rates of return of spontaneous circulation (ROSC) similar to right atrial (RA) epinephrine.

Methods and Results

Forty‐four lambs were randomized into the following groups: RA epinephrine (0.03 mg/kg), low UVC epinephrine (0.03 mg/kg), postcompression ETT epinephrine (0.1 mg/kg), and precompression ETT epinephrine (0.1 mg/kg). Asystole was induced by umbilical cord occlusion. Resuscitation was initiated following 5 minutes of asystole. Thirty‐eight of 44 lambs achieved ROSC (10/11, 9/11, and 12/22 in the RA, UVC, and ETT groups, respectively; subsequent RA epinephrine resulted in a total ROSC of 19/22 in the ETT groups). Median time (interquartile range) to achieve ROSC was significantly longer in the ETT group (including those that received RA epinephrine) compared to the intravenous group (4.5 [2.9–7.4] versus 2 [1.9–3] minutes; P=0.02). RA and low UVC epinephrine administration achieved comparable peak plasma epinephrine concentrations (470±250 versus 450±190 ng/mL) by 1 minute compared to ETT values of 130±60 ng/mL at 5 minutes; P=0.03. Following ROSC with ETT epinephrine alone, there was a delayed peak epinephrine concentration (652±240 ng/mL).

Conclusions

The absorption of ETT epinephrine is low and delayed at birth. RA and low UVC epinephrine rapidly achieve high plasma concentrations resulting in ROSC.

Time to Epinephrine and Survival After Pediatric In-Hospital Cardiac Arrest

IMPORTANCE

Delay in administration of the first epinephrine dose is associated with decreased survival among adults after in-hospital, nonshockable cardiac arrest. Whether this association is true in the pediatric in-hospital cardiac arrest population remains unknown.

OBJECTIVE

To determine whether time to first epinephrine dose is associated with outcomes in pediatric in-hospital cardiac arrest.

DESIGN, SETTING AND PARTICIPANTS

We performed an analysis of data from the Get With the Guidelines-Resuscitation registry. We included US pediatric patients (age <18 years) with an in-hospital cardiac arrest and an initial nonshockable rhythm who received at least 1 dose of epinephrine. A total of 1558 patients (median age, 9 months [interquartile range [IQR], 13 days-5 years]) were included in the final cohort.

EXPOSURE

Time to epinephrine, defined as time in minutes from recognition of loss of pulse to the first dose of epinephrine.

MAIN OUTCOMES AND MEASURES

The primary outcome was survival to hospital discharge. Secondary outcomes included return of spontaneous circulation (ROSC), survival at 24 hours, and neurological outcome. A favorable neurological outcome was defined as a score of 1 to 2 on the Pediatric Cerebral Performance Category scale.

RESULTS

Among the 1558 patients, 487 (31.3%) survived to hospital discharge. The median time to first epinephrine dose was 1 minute (IQR, 0-4; range, 0-20; mean [SD], 2.6 [3.4] minutes). Longer time to epinephrine administration was associated with lower risk of survival to discharge in multivariable analysis (multivariable-adjusted risk ratio [RR] per minute delay, 0.95 [95% CI, 0.93-0.98]). Longer time to epinephrine administration was also associated with decreased risk of ROSC (multivariable-adjusted RR per minute delay, 0.97 [95% CI, 0.96-0.99]), decreased risk of survival at 24 hours (multivariable-adjusted RR per minute delay, 0.97 [95% CI, 0.95-0.99]), and decreased risk of survival with favorable neurological outcome (multivariable-adjusted RR per minute delay, 0.95 [95% CI, 0.91-0.99]). Patients with time to epinephrine administration of longer than 5 minutes (233/1558) compared with those with time to epinephrine of 5 minutes or less (1325/1558) had lower risk of in-hospital survival to discharge (21.0% [49/233] vs 33.1% [438/1325]; multivariable-adjusted RR, 0.75 [95% CI, 0.60-0.93]; P = .01).

CONCLUSIONS AND RELEVANCE

Among children with in-hospital cardiac arrest with an initial nonshockable rhythm who received epinephrine, delay in administration of epinephrine was associated with decreased chance of survival to hospital discharge, ROSC, 24-hour survival, and survival to hospital discharge with a favorable neurological outcome.

Neonatal resuscitation: evolving strategies

Birth asphyxia accounts for about 23% of the approximately 4 million neonatal deaths each year worldwide (Black et al., Lancet, 2010, 375(9730):1969-87). The majority of newborn infants require little assistance to undergo physiologic transition at birth and adapt to extrauterine life. Approximately 10% of infants require some assistance to establish regular respirations at birth. Less than 1% need extensive resuscitative measures such as chest compressions and approximately 0.06% require epinephrine (Wyllie et al. Resuscitation, 2010, 81 Suppl 1:e260–e287). Transition at birth is mediated by significant changes in circulatory and respiratory physiology. Ongoing research in the field of neonatal resuscitation has expanded our understanding of neonatal physiology enabling the implementation of improved recommendations and guidelines on how to best approach newborns in need for intervention at birth. Many of these recommendations are extrapolated from animal models and clinical trials in adults. There are many outstanding controversial issues in neonatal resuscitation that need to be addressed. This article provides a comprehensive and critical literature review on the most relevant and current research pertaining to evolving new strategies in neonatal resuscitation. The key elements to a successful neonatal resuscitation include ventilation of the lungs while minimizing injury, the judicious use of oxygen to improve pulmonary blood flow, circulatory support with chest compressions, and vasopressors and volume that would hasten return of spontaneous circulation. Several exciting new avenues in neonatal resuscitation such as delayed cord clamping, sustained inflation breaths, and alternate vasopressor agents are briefly discussed. Finally, efforts to improve resuscitative efforts in developing countries through education of basic steps of neonatal resuscitation are likely to decrease birth asphyxia and neonatal mortality.

Drugs during delivery room resuscitation--what, when and why?

Although seldom needed, the short list of medications used for delivery room resuscitation of the newborn includes epinephrine and volume expanders. Naloxone, sodium bicarbonate and the use of other vasopressors are no longer considered helpful during acute resuscitation and are more often administered in the post-resuscitative period under special circumstances. This review examines the existing literature for the two commonly used medications in neonatal resuscitation and identifies the many knowledge gaps requiring further research.

Cardiopulmonary resuscitation with chest compressions during sustained inflations: a new technique of neonatal resuscitation that improves recovery and survival in a neonatal porcine model

BACKGROUND

Guidelines on neonatal resuscitation recommend 90 chest compressions (CCs) and 30 manual inflations (3:1) per minute in newborns. The study aimed to determine whether CC s during sustained inflations (SIs) improves the recovery of asphyxiated newborn piglets in comparison with coordinated 3:1 resuscitation.

METHODS AND RESULTS

Term newborn piglets (n=8/group) were anesthetized, intubated, instrumented, and exposed to 45-minute normocapnic hypoxia followed by asphyxia. Piglets were randomly assigned to receive either 3:1 resuscitation (3:1 group) or CCs during SIs (SI group) when the heart rate decreased to 25% of baseline. Piglets randomly assigned to the SI group received SIs with a pressure of 30 cm H2O for 30 s. During the SI, CCs at a rate of 120/min were provided. SI was interrupted after 30 s for 1 s before a further 30-s SI was provided. CCs were continued throughout SIs. CCs and SI were continued until the return of spontaneous circulation. Continuous respiratory parameters, cardiac output, mean systemic and pulmonary artery pressures, and regional blood flows were measured. Mean (standard deviation) time for return of spontaneous circulation was significantly reduced in SI group versus 3:1 group (32 [11] s versus 205 [113] s, respectively). In the SI group, administration of oxygen and epinephrine was significantly lower, whereas minute ventilation and exhaled CO2 were significantly increased. The SI group had significantly higher mean systemic and pulmonary arterial pressures during resuscitation in comparison with the 3:1 group (51 [10] versus 31 [5] mm Hg; 41[7] versus 31 [7] mm Hg, respectively; all P<0.05), with improved cardiac output and carotid blood flow.

CONCLUSIONS

Combining CCs and SIs significantly improved the return of spontaneous circulation with better hemodynamic recovery in asphyxiated newborn piglets in comparison with standard coordinated 3:1 resuscitation.