Affiliations: Section of Critical Care Medicine, Department of Pediatrics, College of Medicine, University of Arkansas for Medical Sciences, Little Rock, AR, USA | Respiratory Care, Arkansas Children’s Hospital, Little Rock, AR, USA
Note:  Corresponding author:Mark J. Heulitt, Professor of Pediatrics, Physiology and Biophysics, Critical Care Medicine, Arkansas Children’s Hospital, 800 Marshall Street, Little Rock, AR 72202, USA. Tel.: +1 501 364 1858; Fax: +1 501 364 3188; E-mail: [email protected]
Abstract: Goals of modern mechanical ventilation in infants focus on preventing over-distention by limiting tidal volume. Accurate measurement of these volumes is essential. We hypothesized that tidal volume accuracy differs dependent upon the type of airway sensor utilized in tidal volumes less than 10 mL. Intubated, sedated Sprague Dawley rats (n = 40) were ventilated utilizing both control and support ventilator modes. Accuracy of volume delivery was compared between a fixed orifice flow sensor (FOF) and a hot wire anemometer (HWA) to a Hans Rudolph linear pneumotachograph positioned at the patient wye. Rats median weight was 476 grams (range 370–544), tidal volume (VT) 3.5 mL (1.2–11.4), f 50 (18–102), and PIP 9.5 cm H2O (1–34). Across all modes, bias and precision were HWA −0.76, 1.09; FOF 0.22, 0.61. This study confirms that there are differences in the accuracy of small tidal volumes measured with a FOF as compared to a HWA. Utilizing a FOF, control modes exhibit improved precision and decreased bias as compared to support modes.
Keywords: Pediatric, critical care, artificial, respiration, monitoring, ventilation