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Improved blood flow during prolonged cardiopulmonary resuscitation with 30% duty cycle in infant pigs
J M Dean1, R C Koehler, C L Schleien
1Department of Anesthesiology and Critical Care Medicine, Johns Hopkins Medical Institutions, Baltimore, Md.
Insights
A shorter compression duty cycle significantly improves blood flow to the heart and brain during cardiopulmonary resuscitation (CPR) in infants. This study suggests current CPR guidelines may need revision for pediatric patients.
Area of Science:
- Pediatric Resuscitation Science
- Cardiovascular Physiology
- Neurocritical Care
Background:
- Current cardiopulmonary resuscitation (CPR) guidelines recommend sustained compression to optimize myocardial and cerebral blood flow.
- The effectiveness of different compression rates and duty cycles on perfusion during infant CPR requires further investigation.
Purpose of the Study:
- To compare myocardial and cerebral perfusion during CPR in a 2-week-old swine model using varying compression rates and duty cycles.
- To determine the optimal compression duty cycle for maintaining vital organ blood flow during prolonged CPR in infants.
Main Methods:
- Anesthetized 2-week-old swine underwent CPR with a pneumatic device at either 100 compressions/min with a 60% duty cycle, 100 compressions/min with a 30% duty cycle, or 150 compressions/min with a 30% duty cycle.
- Myocardial and cerebral blood flow were measured using microspheres, alongside arterial and sagittal sinus blood gas analysis, throughout 50 minutes of CPR.
- Chest deformation and loss of recoil were assessed to evaluate compression quality.
Main Results:
- While initial perfusion was similar across groups, prolonged CPR demonstrated significantly higher myocardial and cerebral blood flow with a 30% duty cycle compared to a 60% duty cycle.
- By 35 minutes, the 60% duty cycle resulted in critically low flow (<5 ml/min/100g) to myocardial regions, whereas the 30% duty cycle maintained flow >25 ml/min/100g.
- Brain regions received 50% less flow with the 60% duty cycle by 20 minutes, and cerebral oxygen uptake was better preserved with the 30% duty cycle.
- Greater chest deformation and loss of recoil were observed with the 60% duty cycle.
Conclusions:
- A shorter compression duty cycle (30%) provides superior myocardial and cerebral perfusion during prolonged CPR in an infant swine model.
- These findings do not support current recommendations for prolonged compressions at 100/min with a 60% duty cycle during infant CPR.
- Optimizing the compression duty cycle is crucial for improving resuscitation outcomes in pediatric patients.
Background:
Sustained compression is recommended to maximize myocardial and cerebral blood flow during cardiopulmonary resuscitation (CPR) in adults and children. We compared myocardial and cerebral perfusion during CPR in three groups of 2-week-old anesthetized swine using compression rates and duty cycles (duration of compression/total cycle time) of 100 per minute, 60%; 100 per minute, 30%; and 150 per minute, 30%.
Methods And Results:
Ventricular fibrillation was induced and CPR was begun immediately with a sternal pneumatic compressor. Epinephrine was continuously infused during CPR. Microsphere-determined blood flow and arterial and sagittal sinus blood gas measurements were made before cardiac arrest was induced and after 5, 10, 20, 35, and 50 minutes of CPR. At 5 minutes of CPR, ventricular and cerebral blood flows were greater than 25 ml.min-1 x 100 g-1 and were not significantly different between groups. When CPR was prolonged, however, myocardial and cerebral blood flows were significantly higher with the 30% duty cycle than with the 60% duty cycle. By 35 minutes, all myocardial regions had less than 5 ml.min-1 x 100 g-1 flow with the 60% duty cycle. In contrast, CPR with the 30% duty cycle at either compression rate provided more than 25 ml.min-1 x 100 g-1 to all ventricular regions for 50 minutes. By 20 minutes, most brain regions received 50% less flow with the 60% duty cycle compared with animals undergoing CPR with the 30% duty cycle (p less than 0.05). Cerebral oxygen uptake was better preserved with the 30% duty cycle. Chest deformation from loss of recoil was greater with the 60% duty cycle compared with the 30% duty cycle.
Conclusions:
We conclude that the shorter duty cycle provides markedly superior myocardial and cerebral perfusion during 50 minutes of CPR in this infant swine model. These data do not support recommendations for prolonged compression at rates of 100 per minute during CPR in infants and children.