Reductions in dead space ventilation with nasal high flow depend on physiological dead space volume: metabolic hood measurements during sleep in patients with COPD and controls

• Nasal high flow (NHF) reduces minute ventilation and ventilatory loads during sleep but the mechanisms are not clear. We hypothesised NHF reduces ventilation in proportion to physiological but not anatomical dead space. 11 subjects (five controls and six chronic obstructive pulmonary disease (COPD) patients) underwent polysomnography with transcutaneous carbon dioxide (CO2) monitoring under a metabolic hood. During stable non-rapid eye movement stage 2 sleep, subjects received NHF (20 L center dot min(-1)) intermittently for periods of 5-10 min. We measured CO2 production and calculated dead space ventilation. Controls and COPD patients responded similarly to NHF. NHF reduced minute ventilation (from 5.6 +/- 0.4 to 4.8 +/- 0.4 L center dot min(-1); p< 0.05) and tidal volume (from 0.34 +/- 0.03 to 0.3 +/- 0.03 L; p< 0.05) without a change in energy expenditure, transcutaneous CO2 or alveolar ventilation. There was a significant decrease in dead space ventilation (from 2.5 +/- 0.4 to 1.6 +/- 0.4 L center dot min(-1); p< 0.05), but not in respiratory rate. The reduction in dead space ventilation correlated with baseline physiological dead space fraction (r(2)=0.36; p< 0.05), but not with respiratory rate or anatomical dead space volume. During sleep, NHF decreases minute ventilation due to an overall reduction in dead space ventilation in proportion to the extent of baseline physiological dead space fraction.

Ämnesord

MEDICIN OCH HÄLSOVETENSKAP  -- Klinisk medicin -- Lungmedicin och allergi (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Clinical Medicine -- Respiratory Medicine and Allergy (hsv//eng)

Nyckelord

hypoxemic respiratory-failure

cannula

oxygen

therapy

work

infants

disease

Respiratory System

akrabarti mk

1986

british journal of anaesthesia

v58

p11

wler ws

1948

journal of clinical investigation

v27

p327

Publikations- och innehållstyp

ref (ämneskategori)

art (ämneskategori)