Determinants of pulmonary dead space in ventilated newborn infants

Abstract

Numerous factors influence pulmonary dead space and thus an optimum tidal volume will differ according to the underlying demographics and respiratory status.

Predictors of outcome of prematurely born infants with pulmonary interstitial emphysema

“…As a consequence, there is ventilation‐perfusion (V A /Q) mismatch . This results in a decrease in ventilation efficiency and hypoxia and also an increase in dead space ventilation . As a result, increased tidal volumes are required to maintain carbon dioxide clearance as we have demonstrated in this study.…”

Physiological and anatomical dead space in mechanically ventilated newborn infants

“…Dead space can be calculated using the concentration of carbon dioxide (CO 2 ) in expired breaths measured by capnography. Few studies, however, have used capnography to calculate dead space in ventilated infants as it has previously been problematic in prematurely born infants because of technical limitations arising from their high respiratory rates and small tidal volumes and the use of un‐cuffed endotracheal tubes (ET) as there may be leakage around such ETs . Recently, sensitive, low dead‐space CO 2 sensors combined with flow sensors have made the application of real time capnography feasible as a tool to estimate pulmonary dead space at the bedside.…”

Tidal Volumes and Outcome of Extubation in Mechanically Ventilated Premature Infants

“…In the absence of studies reporting on the outcome of extubation relative to V T s at extubation, the sample size calculation was based on the observation that prematurely born infants who later developed BPD had a V T which was 2.6 mL/kg higher than prematurely born infants who did not develop BPD. 7 The standard deviation of V T /kg was 1.4 mL/kg. 16 Fifteen subjects in each group enabled detection of a difference in V T /kg of 2.6 mL/kg between the two groups with 95% power at the 1% level.…”

“…5 This wide range of values might be explained by the observation that alveolar dead space increases with a longer duration of mechanical ventilation and weight-adjusted anatomical dead space increases with lower gestation and body weight. 6,7 In evolving BPD, altered respiratory mechanics, such as increased resistance, necessitate the provision of "supraphysiologically" high V T s. 5 While some experts have recommended actual values for the targeted V T , 3,8,9 very few studies have investigated weaning strategies and targeted V T at extubation. Ventilating at very high V T would cause alveolar damage and volutrauma, 10 while weaning and extubating from a very low V T might cause atelectasis and alveolar collapse which would impact on the outcome of extubation and increase the chance of extubation failure.…”