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.

Is renal tissue oxygen desaturation during severe hypoxia underestimated? An observational study in term newborn piglets.

The kidney is an organ highly susceptible to injury by regional tissue oxygen desaturation during hypoxic episodes. Transcutaneous monitoring of renal tissue oxygen saturation is therefore of increasing interest. The aim of the present study was to compare renal tissue oxygen saturation measured by near-infrared spectroscopy (NIRS) during acute hypoxia in neonates directly on the kidney and transcutaneously. We hypothesized that transcutaneous renal tissue oxygen saturation measurements would be influenced by superficial tissue. Five term newborn piglets were anesthetized, instrumented and exposed to normocapnic hypoxia at an inspired oxygen concentration of 0.14. Regional tissue oxygen saturation (rSO2) was simultaneously measured for comparison with the sensor of NIRS (Invos 5100, Somanetics Corp., Troy, MI, USA) applied directly on the left kidney (renaldirect rSO2) and on the skin of right flank above the right kidney (renalskin rSO2). Cerebral regional tissue oxygenation (cerebralskin rSO2), arterial oxygen saturation, heart rate (HR) and mean arterial pressure (MAP) were also monitored. NIRS parameters were analyzed in 5 s intervals during first 2 min of hypoxia. Hypoxia was achieved with an arterial oxygen desaturation from median (range) 95.3% (86.8-98.0) to 23.5% (13.0-41.0) after 2 min. HR and MAP did not change significantly during hypoxia. There were pronounced and lower renaldirect rSO2 readings when compared with those of renalskin rSO2 with significant differences from 25 to 55 s after initiation of hypoxia. Changes of cerebralskin rSO2 and renalskin rSO2 were similar. Transcutaneous monitoring of renal tissue oxygen saturation may underestimate acute oxygen desaturation of the kidney during hypoxia in neonates.

Chest Compressions during Sustained Inflations Improve Recovery When Compared to a 3:1 Compression:Ventilation Ratio during Cardiopulmonary Resuscitation in a Neonatal Porcine Model of Asphyxia.

BACKGROUND: Recently, sustained inflations (SI) during chest compression (CC) (CC+SI) have been suggested as an alternative to the current approach during neonatal resuscitation. No previous study compared CC+SI using CC rates of 90/min to the current 3:1 compression:ventilation ratio (C:V). OBJECTIVE: To determine whether CC+SI versus a 3:1 C:V reduces the time to the return of spontaneous circulation (ROSC) and improves hemodynamic recovery in newborn piglets with asphyxia-induced bradycardia. INTERVENTION AND MEASUREMENTS: Term newborn piglets were anesthetized, intubated, instrumented, and exposed to 45-min normocapnic hypoxia followed by asphyxia. Cardiopulmonary resuscitation (CPR) was initiated when the heart rate decreased to 25% of baseline. Piglets were randomized into 3 groups: CC during SI at a rate of 90 CC/min (SI+CC 90, n = 8), a 3:1 C:V using 90 CC and 30 inflations (3:1, n = 8), or a sham group (n = 6). Cardiac function, carotid blood flow, cerebral oxygenation, and respiratory parameters were continuously recorded throughout the experiment. RESULTS: CC+SI significantly reduced the median (IQR) time of ROSC, i.e., 34 s (28-156 s) versus 210 s (72-300 s) in the 3:1 group (p = 0.048). CC+SI also significantly reduced the requirement for 100% oxygen, improved respiratory parameters, and resulted in a similar hemodynamic recovery. CONCLUSIONS: CC+SI during CPR significantly improved ROSC in a porcine model of neonatal resuscitation. This is of considerable clinical relevance because improved respiratory and hemodynamic parameters potentially minimize morbidity and mortality in newborn infants.

Return of spontaneous Circulation Is Not Affected by Different Chest Compression Rates Superimposed with Sustained Inflations during Cardiopulmonary Resuscitation in Newborn Piglets.

OBJECTIVE: Recently, sustained inflations (SI) during chest compression (CC) have been suggested as an alternative to the current approach during neonatal resuscitation. However, the optimal rate of CC during SI has not yet been established. Our aim was to determine whether different CC rates during SI reduce time to return of spontaneous circulation (ROSC) and improve hemodynamic recovery in newborn piglets with asphyxia-induced bradycardia. INTERVENTION AND MEASUREMENTS: Term newborn piglets were anesthetized, intubated, instrumented and exposed to 45-min normocapnic hypoxia followed by asphyxia. Resuscitation was initiated when heart rate decreased to 25% of baseline. Piglets were randomized into three groups: CC superimposed by SI at a rate of 90 CC per minute (SI+CC 90, n = 8), CC superimposed by SI at a rate of 120 CC per minute (SI+CC 120, n = 8), or a sham group (n = 6). Cardiac function, carotid blood flow, cerebral oxygenation and respiratory parameters were continuously recorded throughout the experiment. MAIN RESULTS: Both treatment groups had similar time of ROSC, survival rates, hemodynamic and respiratory parameters during cardiopulmonary resuscitation. The hemodynamic recovery in the subsequent 4h was similar in both groups and was only slightly lower than sham-operated piglets at the end of experiment. CONCLUSION: Newborn piglets resuscitated by SI+CC 120 did not show a significant advantage in ROSC, survival, and hemodynamic recovery as compared to those piglets resuscitated by SI+CC 90.

Change in tidal volume during cardiopulmonary resuscitation in newborn piglets.

INTRODUCTION: The purpose of inflations during cardiopulmonary resuscitation (CPR) is to deliver an adequate tidal volume (VT) to facilitate gas exchange. However, no study has examined VT delivery during chest compression (CC) in detail to understand the effect of CC on lung aeration. The aim of the study was to examine VT changes during CC and their effect on lung aeration. METHODS: Piglets were anaesthetised, instrumented and intubated with zero leak. They were then randomly assigned to CPR using either 3:1 compression:ventilation ratio (C:V) (n=6), continuous CC with asynchronous ventilations (CCaV) (90 CC/min with 30/min asynchronous ventilations) (n=6) or continuous CC superimposed with 30 s sustained inflations (CC+SI) with a CC rate of 120/min (n=5). A respiratory function monitor (NM3, Respironics, Philips, Andover, Massachusetts, USA) was used to continuously measure inspiration tidal volume (VTi) and expirational tidal volume (VTe). ANOVA with Bonferroni post-test were used to compare variables of all three groups. RESULTS: During the inflation in the 3:1 C:V group, the mean (SD) VTi and VTe was 23.5 (5.3) mL/kg and 19.4 (2.7) mL/kg (p=0.16), respectively. During the CC, we observed a significant VT loss in the 3:1 group with VTi and VTe being 4.1 (1.2) mL/kg and 11.1 (3.3) mL/kg (p=0.007), respectively. In the CCaV group, VTe was higher compared with VTi, but this was not significant. In the CC+SI group, a VT gain during each CC with VTi and VTe of 16.3 (3.2) mL/kg and 14 (3) mL/kg (p=0.21), respectively, was observed. CONCLUSIONS: VT delivery is improved using CC+SI compared with 3:1 C:V. This improvement in VT delivery may lead to better alveolar oxygen delivery and lung aeration.

Respiratory function and near infrared spectroscopy recording during cardiopulmonary resuscitation in an extremely preterm newborn.

We describe a case highlighting several controversial and important topics regarding neonatal cardiopulmonary resuscitation (CPR). Current neonatal guidelines recommend a 3:1 compression:ventilation ratio; however, the most effective ratio of delivering chest compressions (CC) remains controversial. We report a case of a male infant at 24 weeks' postmenstrual age weighing 650 g on a background of preterm labor. At initial assessment the infant appeared floppy and apneic with a heart rate (HR) of 50-60 beats/min. Mask ventilation was ineffective, thus continuous CC (90/min) with asynchronous ventilations (60/min) was started. HR, blood pressure, oxygen saturation, cerebral oxygenation, respiratory function, and exhaled carbon dioxide (ECO2) were continuously measured during CPR. Return of spontaneous circulation defined as HR >60/min was achieved after 90 s of CPR. Mask leak significantly increased during CC. During bradycardia (HR ∼50/min), ECO2 indicated correct tube placement and an increase of ECO2 >12 mm Hg was associated with rapid increase in HR >60/min.