Effect of residual leaning force on intrathoracic pressure during mechanical ventilation in children
ABSTRACT Determine the effect of residual leaning force on intrathoracic pressure (ITP) in healthy children receiving mechanical ventilation. We hypothesized that application of significant residual leaning force (2.5kg or 20% of subject body weight) would be associated with a clinically important change in ITP.
IRB-approved pilot study of healthy, anesthetized, paralyzed mechanically ventilated children (6 months to 7 years). Peak endotracheal pressure (ETP), a surrogate of ITP, was continuously measured before and during serial incremental increases in sternal force from 10% to 25% of the subject's body weight. A delta ETP of >or=2.0cmH(2)O was considered clinically significant.
13 healthy, anesthetized, paralyzed mechanically ventilated children (age: 26+/-24m, range: 6.5-87m; weight: 13+/-5kg, range: 7.4-24.8kg) were enrolled. Peak ETP increased from baseline for all force applications (10% body weight: mean difference of 0.8cmH(2)O, p<0.01; 15% body weight: mean difference of 1.1cmH(2)O, p<0.01; 20% body weight: mean difference of 1.5cmH(2)O, p<0.01; 25% body weight: mean difference of 1.89cmH(2)O, p<0.01). Residual leaning force of >or=2.5kg was associated with a 2.0cmH(2)O change in peak ETP (odds ratio 7.5; CI(95) 1.5-37.7; p=0.014) while sternal force >or=20% body weight was not (odds ratio 2.4; CI(95) 0.6-9.2; p=0.2).
In healthy anesthetized children, changes in ETP were detectable at residual leaning forces as low as 10% of subject body weight. Residual leaning force of 2.5kg was associated with increases in ETP >or=2.0cmH(2)O.
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ABSTRACT: Cardiopulmonary resuscitation (CPR) guidelines recommend complete release between chest compressions (CC). Evaluate the hemodynamic effects of leaning (incomplete chest wall release) during CPR and the prevalence of leaning during CPR. In piglet ventricular fibrillation cardiac arrests, 10% and 20% (1.8 kg and 3.6 kg, respectively), leaning during CPR increased right atrial pressures, decreased coronary perfusion pressures, and decreased cardiac index and left ventricular myocardial blood flow by nearly 50%. In contrast, residual leaning of a 260 g accelerometer/force feedback device did not adversely affect cardiac index or myocardial blood flow. Among 108 adult in-hospital CPR events, leaning ≥ 2.5 kg was demonstrable in 91% of the events and 12% of the evaluated CC. For 12 children with in-hospital CPR, 28% of CC had residual leaning ≥ 2.5 kg and 89% had residual leaning ≥ 0.5 kg. Leaning during CPR increases intrathoracic pressure, decreases coronary perfusion pressure, and decreases cardiac output and myocardial blood flow. Leaning is common during CPR.Resuscitation 12/2011; 82 Suppl 2:S23-6. DOI:10.1016/S0300-9572(11)70147-2 · 3.96 Impact Factor
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ABSTRACT: Poor survivability following infant cardiac arrest has been attributed to poor quality chest compressions. Current infant CPR manikins, used to teach and revise chest compression technique, appear to limit maximum compression depths (CDmax) to 40mm. This study evaluates the effect of a more "physiological" CDmax on chest compression quality and assesses whether proposed injury risk thresholds are exceeded by thoracic over-compression. A commercially available infant CPR manikin was instrumented to record chest compressions and modified to enable compression depths of 40mm (original; CDmax(40)) and 56mm (the internal thoracic depth of a three-month-old male infant; CDmax(56)). Forty certified European Paediatric Life Support instructors performed two-thumb (TT) and two-finger (TF) chest compressions at both CDmax settings in a randomised crossover sequence. Chest compression performance was compared to recommended targets and compression depths were compared to a proposed thoracic over-compression threshold. Compressions achieved greater depths across both techniques using the CDmax(56), with 44% of TT and 34% of TF chest compressions achieving the recommended targets. Compressions achieved depths that exceeded the proposed intra-thoracic injury threshold. The modified manikin (CDmax(56)) improved duty cycle compliance; however, the chest compression rate was consistently too high. Overall, the quality of chest compressions remained poor in comparison with internationally recommended guidelines. This data indicates that the use of a modified manikin (CDmax(56)) as a training aid may encourage resuscitators to habitually perform deeper chest compressions, whilst avoiding thoracic over-compression and thereby improving current CPR quality. Future work will evaluate resuscitator performance within a more realistic, simulated CPR environment.Resuscitation 10/2012; 84(5). DOI:10.1016/j.resuscitation.2012.10.005 · 3.96 Impact Factor
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ABSTRACT: BACKGROUND: Morbidity and mortality remain high following infant cardiac arrest. Optimal cardiopulmonary resuscitation (CPR) is therefore imperative. OBJECTIVE: Comparison of two-thumb (TT) and two-finger (TF) infant chest compression technique compliance with international recommendations. DESIGN: Randomised cross-over experimental study. METHODS: Twenty-two certified Advanced Paediatric Life Support (APLS) instructors performed 2 min continuous TT and TF chest compressions on an instrumented infant CPR manikin. Compression depth (CD), release force (RF), compression rate (CR) and duty cycles (DCs) were recorded. Quality indices were developed to calculate the proportion of compressions that complied with internationally recommended targets, and an overall quality index was used to calculate the proportion that complied with all four targets. RESULTS: Mean CD was 33 mm and 26 mm (p<0.001; target ≥36.7 mm), mean RF was 0.8 kg and 0.2 kg (p<0.001; target <2.5 kg), mean CR was 128/min and 131/min (p=0.052; target 100-120/min) and mean DCs was 61% and 53% (p<0.001; target 30-50%) for the TT and TF techniques, respectively. With the exception of RF, the majority of compressions failed to comply with targets. The TT technique improved median CD compliance (6% vs 0% (p<0.001)), while the TF technique improved median DC compliance (23% vs 0% (p<0.001)). Overall compliance with all four targets was <1% for both techniques (p=0.14). CONCLUSIONS: Compliance of APLS instructors with current international recommendations during simulated infant CPR is poor. The TT technique provided improved CD compliance, while the TF technique provided superior DC compliance. If this reflects current clinical practice, optimisation of performance to achieve international recommendations during infant CPR is called for.Archives of Disease in Childhood 11/2012; 98(8). DOI:10.1136/archdischild-2012-302583 · 2.91 Impact Factor