Korean J Anesthesiol.  1997 May;32(5):710-714. 10.4097/kjae.1997.32.5.710.

Changes of Arterial Carbon Dioxide Tension Do Not Affect Respiratory System Mechanics in Enflurane Anesthetized Cats

• Kim JU
• Sim JY
• Lee BW
• Choi IC
• Park PH
• Lee DM

• KMID: 2240227
• DOI: http://doi.org/10.4097/kjae.1997.32.5.710

Abstract

BACKGROUND
Bronchoconstriction is known to be induced by hypocarbia or hypercarbia. But the above effect has not been studied during general anesthesia. This study was proposed to investigate the effects of hypocarbia and hypercarbia on the respiratory system mechanics in 0.5 MAC enflurane anesthetized cats.
METHODS
Six cats, weighing 3.0~3.6 kg were used. Pentobarbital sodium was intraperitonially injected to induce anesthesia and endotracheal intubation was followed. The anesthesia was maintained by 0.5 MAC enflurane, oxygen, and air (FiO2; 0.5). Intermittent mandatory ventilation was applied with Siemens Servo 900C ventilator. The inspiratory flow rate and tidal volume were fixed througout the experiment. Only the respiratory rate was adjusted to achieve normocarbia(PaCO2; 31~38 mmHg), hypercarbia(PaCO2; 38~45 mmHg) and hypocarbia(PaCO2; 24~31 mmHg), which were done not in the order. We used the flow-interruption technique to measure respiratory mechanics. The course of changes in the pressure along with the prefixed flow rate and volume were monitored and recorded with Bicore CP100 pulmonary monitor. The data were transfered to a PC and analyzed by Anadat processing software. Total respiratory system, airway and tissue viscoelastic resistances, and dynamic and static compliances were calculated for normocarbia, hypercarbia and hypocarbia.
RESULTS
There are no significant differences of resistances and compliances of respiratory system among hypocarbia, normocarbia and hypercarbia.
CONCLUSIONS
The changes in PaCO2 do not influence significantly the resistances and compliances measured by the flow interruption technique used in the study.

Keyword

Anesthetics; volatile; enflurane; Carbon dioxide; hypercarbia; hypocarbia; Lung; airway resistance; compliance

MeSH Terms

Airway Resistance
Anesthesia
Anesthesia, General
Anesthetics
Animals
Bronchoconstriction
Carbon Dioxide*
Carbon*
Cats*
Compliance
Enflurane*
Intubation, Intratracheal
Lung
Mechanics*
Oxygen
Pentobarbital
Respiratory Mechanics
Respiratory Rate
Respiratory System*
Tidal Volume
Ventilation
Ventilators, Mechanical
Anesthetics
Carbon
Carbon Dioxide
Enflurane
Oxygen
Pentobarbital