Related Experiment Video
Updated: Aug 5, 2026

Expired CO2 Measurement in Intubated or Spontaneously Breathing Patients from the Emergency Department
Published on: January 29, 2011
Controlled ventilation with the Bain co-axial system. A rationalisation of gender-related minute volume requirements
1Riyadh Armed Forces Hospital, Kingdom of Saudi Arabia.
Abstract:
The minute ventilation required to maintain either hypocapnia (FE'CO2 = 4.0 kPa, group A, n = 36) or normocapnia (FE'CO2 = 5.0 kPa, group B, n = 38) in 74 adult patients was determined for the Bain system with controlled ventilation at 10 breath.min-1 and fresh gas flow equal to minute ventilation. Males required a greater minute ventilation and fresh gas flow than females (p < 0.01) in each group (group A, males approximately 90 ml.min-1.kg-1, females approximately 80 ml.min-1.kg-1; group B, males approximately 75 ml.min-1.kg-1; females approximately 65 ml.min-1.kg-1). Where capnography is not available, it may be safer to ventilate patients' lungs using the minute volume and fresh gas flow requirements established in group A patients. The administration of 5% carbon dioxide in oxygen for 2 min safely re-established normocapnia and spontaneous respiration in hypocapnic patients when ventilated with the same minute volume, fresh gas flow and respiratory rate required during surgery. Only one patient required greater than 400 ml.min-1 of carbon dioxide to produce a 5% concentration. Maximum flow from the carbon dioxide flowmeter may be restricted to 400 ml.min-1 rather than the 500 ml.min-1 currently recommended.
More Related Videos
Related Concept Videos
Assessment of Diffusion and Perfusion
The Role of Diffusion in Respiration
Diffusion is the process by which molecules move from an area of higher concentration to an area of lower concentration. In the respiratory system, this principle...
Physiological Control of Respiration
Breathing, a seemingly passive process, is regulated by the respiratory center in the brainstem. This center coordinates the involuntary control of respirations, which means it occurs without conscious effort, ensuring a smooth and uninterrupted pattern.
Regulation of Ventilation
The body maintains ventilation by monitoring levels of carbon dioxide (CO2), oxygen (O2), and hydrogen ion concentration (pH) in the arterial blood. Among these factors, the level of CO2 plays a crucial...
Respiratory Volumes and Capacities
Oxygen Delivering System II: Venturi Mask and Transtracheal Oxygen
Venturi Mask
The Venturi mask, named after the Venturi effect, is designed to deliver precise oxygen concentrations. It consists of a large tube with an oxygen inlet that narrows down, causing a pressure drop that pulls air in through adjustable side ports. The mask is a lightweight,...
Mechanical Ventilation II: Invasive Ventilation
Negative-Pressure Ventilators
Negative-pressure ventilators create a vacuum around the chest or body to draw air into the lungs, simulating breathing. This method does not require an...
Mechanical Ventilation III: Noninvasive Ventilation
Noninvasive Positive-Pressure Ventilation (NIPPV)

