Abstract
Background:
Tidal volume (VT) selection for patients undergoing mechanical ventilation continues to be a controversial issue. While ideal body weight (IBW) has been recommended to calculate the VT in adults, actual body weight (ABW) is often used for both children and adults. The purpose of this study was to determine if the VT selection (based on IBW or ABW) was consistent with a lung protective strategy (<8 mL/kg).
Methods:
Retrospective chart review using EMRs of pediatric and adult patients admitted to a medical and pediatric ICU. Patients less than 1 year of age, patients undergoing non-conventional modes of ventilation (airway pressure release ventilation [APRV], high frequency oscillatory ventilation [HFOV], high frequency jet ventilation [HFJV]) or extracorporeal membrane oxygenation (ECMO) were excluded from the study. Demographic information, vital signs, arterial blood gases, and ventilator parameters upon admission to ICU (FIO2, VT, PEEP) were collected. A VT of 8 mL/kg was defined as protective for comparison and analysis. Instituional IRB approved the study.
Results:
Data was collected from 141 patients (30 children; 111 adults) admitted to the ICU between January of 2016 and March of 2018. Mean pediatric age was 7.3 (± 5.8) years and for adults was 46.6 (± 25.7) years, 44% were female (n = 62) and 56% were male (n = 79). Mean PaO2/FIO2 (PF) ratio in adults was 213, while mean pediatric PF ratio was 278. The ABW was used as IBW in the pediatric group. Mean adult ABW was 56.4 (± 46.2) kg, while mean pediatric actual weight was 29.1 (± 23.9; IQR 25-75: 11.0-49.3) kg. Mean VT was 8.36 (± 3.64) and 7.64 (± 2.55) mL/kg when ABW was used for adult and pediatric patients, respectively (P = .15). Mean adult IBW was 64.0 (± 12.52; IQR 25-75: 52.27-75.45) kg, while mean pediatric ABW was 29.14 (± 23.93; IQR 25-75: 5.3-8.2) kg. When using IBW, the mean VT set for adult patients was 7.19 (± 1.51; range 6.16-10.68; IQR 6.18-8.11) mL/kg and was not significantly different from VT set in pediatric patients (P = .10). However, ten pediatric patients (33.3%) and 42 adults (37.8%) were set on a VT > 8 mL/kg.
Conclusions:
This retrospective chart review demonstrates that while the mean VT selected for these patients was less than 8 mL/kg, a large number of patients received a VT considered outside the range considered as lung protective. Published scientific data suggests evidence that using VT outside the range considered as lung protective is unsafe.
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