Physiological and anatomical dead space in mechanically ventilated newborn infants

Dassios, Theodore; Dixon, Paul; Hickey, Ann; Fouzas, Sotirios; Greenough, Anne

doi:10.1002/ppul.23918

Cited by 26 publications

(25 citation statements)

References 25 publications

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“…Few studies have reported neonate V d,alv values [7,11]. Dassios et al reported a median V d,alv of 0.3 ml/kg in prematurely born infants with a median weight of 1.18 kg, and 0.1 ml/kg for infants with a median weight of 3.3 kg; we report a higher mean V d,alv 0.6-1.0 ml/kg [7].…”

Section: Discussioncontrasting

confidence: 44%

Reduction in minute alveolar ventilation causes hypercapnia in ventilated neonates with respiratory distress

et al. 2020

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Hypercapnia occurs in ventilated infants even if tidal volume (V T) and minute ventilation (V E) are maintained. We hypothesised that increased physiological dead space (V d,phys) caused decreased minute alveolar ventilation (V A ; alveolar ventilation (V A) × respiratory rate) in well-ventilated infants with hypercapnia. We investigated the relationship between dead space and partial pressure of carbon dioxide (PaCO 2) and assessed V A. Intubated infants (n = 33; mean birth weight, 2257 ± 641 g; mean gestational age, 35.0 ± 3.3 weeks) were enrolled. We performed volumetric capnography (V cap), and calculated V d,phys and V A when arterial blood sampling was necessary. PaCO 2 was positively correlated with alveolar dead space (V d,alv) (r = 0.54, p < 0.001) and V d,phys (r = 0.48, p < 0.001), but not Fowler dead space (r = 0.14, p = 0.12). Normocapnia (82 measurements; 35 mmHg ≤ PaCO 2 < 45 mmHg) and hypercapnia groups (57 measurements; 45 mmHg ≤ PaCO 2) were classified. The hypercapnia group had higher V d,phys (median 0.57 (IQR, 0.44-0.67)) than the normocapnia group (median V d,phys /V T = 0.46 (IQR, 0.37-0.58)], with no difference in V T. The hypercapnia group had lower V A (123 (IQR, 87-166) ml/kg/min) than the normocapnia group (151 (IQR, 115-180) ml/kg/min), with no difference in V E. Conclusion: Reduction of V A in well-ventilated neonates induces hypercapnia, caused by an increase in V d,phys .

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Section: Discussioncontrasting

confidence: 44%

Reduction in minute alveolar ventilation causes hypercapnia in ventilated neonates with respiratory distress

et al. 2020

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“…When compared with term-born infants, premature infants have an increased anatomic dead space, so P ETCO 2 is very likely to be lower than arterial CO 2 . 22 We studied the range of CPAP levels in each infant, so factors like the increased dead space and relatively increased ventilation efficiency index did not influence the validity of our conclusions.…”

Section: Discussionmentioning

confidence: 94%

Ventilation Efficiency and Respiratory Muscle Function at Different Levels of CPAP in Intubated Prematurely Born Infants

Dassios

Dixon²,

Greenough

2018

Respir Care

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BACKGROUND: CPAP improves respiratory function in prematurely born infants by establishing and maintaining functional residual capacity, but the level of CPAP that optimizes respiratory function has not been adequately described. We compared ventilation efficiency and respiratory muscle function at different levels of CPAP. METHODS: We studied spontaneously breathing, intubated convalescent premature infants at King's College Hospital NHS Foundation Trust and calculated the ventilation efficiency index and the respiratory muscle time constant of relaxation () at the end of 3 consecutive 5-min periods at 4, 6, and 8 cm H 2 O of CPAP delivered in random order. RESULTS: Between February 2016 and August 2016, 38 infants with a median gestational age of 27 (interquartile range [IQR], 25؊30) weeks and a median birthweight of 0.88 (IQR, 0.73-1.02) kg were studied. At a CPAP level of 6 cm H 2 O, the median ventilation efficiency index was higher (1.52 [IQR, 1.02-2.27]) and median was lower (15.6 [IQR, 10.1-21.3]) s/cm H 2 O] compared with the median ventilation efficiency index (0.75 [IQR, 0.56-1.03]) and median (23.3 [IQR, 15.4-35.2] sec/cm H 2 O) at CPAP of 4 cm H 2 O (P < .001 for both). At a CPAP level of 8 cm H 2 O, median ventilation efficiency index was significantly lower (1.27 [IQR, 1.04-1.91]) and median was not significantly different (11.2 [IQR, 8.3-18.9] s/cm H 2 O) compared with ventilation efficiency index and at CPAP of 6 cm H 2 O (P < .001 and P ‫؍‬ .12, respectively). After multiple logistic regression, the level of CPAP was independently associated with the ventilation efficiency index (adjusted P < .001) and (adjusted P ‫؍‬ .003). CONCLUSIONS: Increasing the level of CPAP from 4 to 6 cm H 2 O was associated with enhanced ventilation efficiency and respiratory muscle function in convalescent premature infants on ventilation, but there was no further benefit from increasing the pressure >6 cm H 2 O.

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“…Dassios et al, compared physiologic and anatomic dead space in a retrospective analysis of mechanically ventilated newborns just prior to extubation. 11 Since the study subjects had largely recovered, their measurements could imply that the premature patients with higher dead space had already sustained some stunting of alveolar development, or that tracheobronchial enlargement, a known complication of prolonged ventilation in premature newborns, was contributing. This is additional evidence that avoiding positive pressure is desirable if not achievable in this population.…”

Section: Preventing Bpd: Practicementioning

confidence: 99%

2018 year in review: Part 2 of 4: Neonatal lung disease

Auten

2019

Pediatric Pulmonology

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Physiological and anatomical dead space in mechanically ventilated newborn infants

Abstract: wileyonlinelibrary.com/journal/ppul

Cited by 26 publications

References 25 publications

Reduction in minute alveolar ventilation causes hypercapnia in ventilated neonates with respiratory distress

Reduction in minute alveolar ventilation causes hypercapnia in ventilated neonates with respiratory distress

Ventilation Efficiency and Respiratory Muscle Function at Different Levels of CPAP in Intubated Prematurely Born Infants

2018 year in review: Part 2 of 4: Neonatal lung disease

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