Work

Reversed ventilatory gap capnometry in ventilated pediatric patients: a brief review for evidence of technical and physiological mechanisms

Year: 2025

Type: article

Abstract: Capnometry measures end-tidal carbon dioxide (P Et CO 2 ) in expired air and is standard practice for monitoring mechanical ventilation in pediatric critical care. P Et CO 2 is often used as a non-invasive indicator for arterial CO 2 (P a CO 2 ), while under normal conditions the P a CO 2 -P Et CO 2 difference is 2–5 mmHg due to imperfect matching of ventilation-perfusion (V/Q). However, in some pediatric patients, a reversed (negative) P(a-Et)CO 2 gradient (ventilatory gap) can be observed, where P Et CO 2 exceeds P a CO 2 . While this phenomenon is commonly linked to underlying technicalities, physiological explanations, including relatively high closing volumes in infants, poorly compliant lung tissue, and elevated mixed venous CO₂ (Pv̅CO₂) due to increased CO₂ production during critical illness, have also been described in the literature. However, current evidence for these mechanisms is limited, and further research is needed to clarify their roles. Possibly, awareness of both technical and physiological factors that may underlie a negative P(a–Et)CO₂ gradient can help clinicians interpret observations more cautiously and consider appropriate adjustments to mechanical ventilation strategies as needed.

Source: Intensive Care Medicine – Paediatric and Neonatal

DOI: 10.1007/s44253-025-00107-z

Authors: R. Klein-Blommert, Reinout A. Bem, D. G. Markhorst

Institutions: Emma Kinderziekenhuis, Amsterdam University Medical Centers

Language: English

Topic: Respiratory Support and Mechanisms

Subfield: Pulmonary and Respiratory Medicine

Field: Medicine

Domain: Health Sciences

SDG: Good health and well-being

Open Access status: hybrid

Estimated APC paid: $2,090