Reference values for volumetric capnography-derived non-invasive parameters in healthy individuals

Abstract

The aim of this study was to determine typical values for non-invasive volumetric capnography (VCap) parameters for healthy volunteers and anesthetized individuals. VCap was obtained by a capnograph connected to the airway opening. We prospectively studied 33 healthy volunteers 32 ± 6 years of age weighing 70 ± 13 kg at a height of 171 ± 11 cm in the supine position. Data from these volunteers were compared with a cohort of similar healthy anesthetized patients ventilated with the following settings: tidal volume (VT) of 6-8 mL/kg, respiratory rate 10-15 bpm, PEEP of 5-6 cmH₂O and FiO₂ of 0.5. Volunteers showed better clearance of CO₂ compared to anesthetized patients as indicated by (median and interquartile range): (1) an increased elimination of CO₂ per mL of VT of 0.028 (0.005) in volunteers versus 0.023 (0.003) in anesthetized patients, p < 0.05; (2) a lower normalized slope of phase III of 0.26 (0.17) in volunteers versus 0.39 (0.38) in anesthetized patients, p < 0.05; and (3) a lower Bohr dead space ratio of 0.23 (0.05) in volunteers versus 0.28 (0.05) in anesthetized patients, p < 0.05. This study presents reference values for non-invasive volumetric capnography-derived parameters in healthy individuals. Mechanical ventilation and anesthesia altered these values significantly.

Analysis of Oxygenation in Chronic Thromboembolic Pulmonary Hypertension Using Dead Space Ratio and Intrapulmonary Shunt Ratio

“…Dead space ratio measurements: We measured the DSR using volumetric capnography (NICO Cardiopulmonary Management System; Novametrix; Wallingford, CT, USA) to calculate the partial pressure of mixed-expired carbon dioxide (PeCO2) according to previous reports. [14][15][16] Using PeCO2 and partial pressure of arterial carbon dioxide (PaCO2) measurements, which were obtained when PeCO2 was measured, the DSR was calculated using the following equation:…”

Volumetric Сapnography As a Tool for Evaluation of Alveolar Ventilation Effectiveness in Clinical Practice

“…-минутной вентиляцией (MV); -дыхательным объемом (VT); -вентиляцией мертвого пространства (анатомического и альвеолярного (VDaw, Vdalv)); -альвеолярной вентиляцией (VA); -частотой дыхания (f). Лишь объем воздуха, достигший альвеол, важен для газообмена, поскольку лишь альвеолы участвует в нем [1][2][3][4]. На объем анатомического мертвого пространства (VDaw) (включая верхние и нижние дыхательные пути вплоть до дыхательных бронхиол) и физиологического мертвого пространства (VDf) (альвеолярного и анатомического) влияет процент воздуха, вдыхаемого за один вдох (VT), доставляемого в альвеолы (например,…”

“…-Minute ventilation (MV) -Tidal volume (VT) -Dead space ventilation (anatomical and alveolar (VDaw, VDalv)) -Alveolar ventilation (VA) -Respiratory frequency (f) Only the volume of air reaching the alveoli is important for gas exchange, because only alveolar segment is involved in the gas exchange [1][2][3][4]. The volume of anatomical dead space (VDaw) (including upper and lower respiratory airways up to respiratory bronchioles) and the functional dead space (VDf) (alveolar and anatomical) is influenced by percentage of air inhaled during one breath (VT) that is delivered to alveoli (e.g.…”

Dead space during one-lung ventilation

“…First, technological advances in volumetric capnography allow an easy, accurate, noninvasive and breath-by-breath determination of dead space at the bedside [2,[5][6][7][8]. Third, ventilatorinduced lung injury (VILI) due to tidal overdistension, a pathophysiological entity thus far difficult to diagnose at the bedside, can now be suspected clinically any time dead space increases beyond normal reference values [14][15][16]. Third, ventilatorinduced lung injury (VILI) due to tidal overdistension, a pathophysiological entity thus far difficult to diagnose at the bedside, can now be suspected clinically any time dead space increases beyond normal reference values [14][15][16].…”