Effect of Alveolar Minute Ventilation on Respiratory Gas Heat Content

University of California (UC) Davis

Status: Completed

Conditions: Ventilation Perfusion Mismatch

Treatments: Other: controlled positive pressure ventilation 9ml/kg tidal volume; Other: controlled positive pressure ventilation 6ml/kg tidal volume

Study type: Observational

Funder types: Other

Identifiers

NCT01943227

483184

Details and patient eligibility

About

This is a single site, prospective, non-blinded, non-randomized, non-interventional study designed to evaluate the effect of changes in alveolar minute ventilation on the measurement of respiratory heat loss (enthalpy).

Full description

This is a single site, prospective, non-blinded, non-randomized, noninterventional study designed to evaluate the effect of changes in alveolar minute ventilation on the measurement of respiratory heat loss (enthalpy). Each patient will serve as their own control. The study will enroll adult patients without cardiac or respiratory illness. It is designed to evaluate the effect of the ventilatory pattern (tidal volume, rate) on respiratory heat loss measured using the VQm™ monitor during standard intra-operative clinical care that requires positive pressure ventilation (PPV)

Enrollment: 20 patients

Sex: All

Ages: 18+ years old

Volunteers: No Healthy Volunteers

Inclusion criteria

• age greater than 18 years
• scheduled for an elective surgical procedure with an anticipated duration of more than 2 hours requiring general anesthesia and positive pressure ventilation using an endotracheal tube
• patient status ASA 1, 2 or 3
• no significant cardio-vascular or respiratory disease
• supine surgical position

Exclusion criteria

• Adults unable to give primary consent
• age less than 18 years
• pregnancy
• prisoners
• pre-existing cardiac or pulmonary disease
• infusion of inotropic drugs
• positive end expiratory pressure (PEEP) requirements >8 cm H2O
• increased intra-abdominal pressure (e.g. planned surgical pneumoperitoneum or ascitis)
• intra-operative patient position other than supine

Trial design

20 participants in 2 patient groups

6ml/kg

Description:

Enthalpy measured in patients receiving controlled positive pressure ventilation 6ml/kg Tidal volume. The VQm monitor samples the gas at a rate of 3 L/min, returning the analyzed gas to the circuit. As the exhaled gas passes through the analytical chamber, the temperature and humidity are measured essentially continuously (40Hz). These data are combined with pressure measurements to determine the exhaled gas volume and then the heat content (enthalpy) is calculated.

Treatment:

Other: controlled positive pressure ventilation 6ml/kg tidal volume

9ml/kg

Description:

Enthalpy measured in patients receiving controlled positive pressure ventilation 9ml/kg Tidal volume. The VQm monitor samples the gas at a rate of 3 L/min, returning the analyzed gas to the circuit. As the exhaled gas passes through the analytical chamber, the temperature and humidity are measured essentially continuously (40Hz). These data are combined with pressure measurements to determine the exhaled gas volume and then the heat content (enthalpy) is calculated.

Treatment:

Other: controlled positive pressure ventilation 9ml/kg tidal volume