The effects of thiopental and generic and nongeneric propofol on respiratory resistance during anesthetic induction in patients with reactive airways.
OBJECTIVE
To demonstrate a favorable effect of propofol on respiratory system resistance during anesthetic induction, and to determine if generic propofol causes adverse effects on respiratory resistance.


METHODS
Randomized pilot study.


METHODS
Anesthetic induction for elective surgery.


METHODS
27 consenting ASA physical status II and III patients with reactive airways (positive smoking history or chronic obstructive pulmonary disease), but not receiving bronchodilator therapy.


METHODS
Patients were randomized equally to one of three anesthetic induction (and maintenance) drugs: sodium thiopental, 5 mg/kg (25 microg/kg/min), generic or nongeneric propofol, 1.25 mg/kg (50 microg/kg/min). They received preinduction midazolam and fentanyl (2 mg and 150 microg) and intravenous lidocaine (0.5 mg/kg). After anesthetic induction, tracheal intubation was established, and predetermined settings for mechanical ventilation were initiated.


METHODS
Immediately after intubation, a sensor was placed on the 8-mm endotracheal tube to detect baseline airway pressure and flow. During maintenance, repeat measurements of pressure and flow were obtained at 2.5-minute intervals for 10 minutes. Respiratory system resistance was derived off-line using the isovolumetric technique.


RESULTS
Patients were similar across groups. The respiratory resistance measured after anesthetic induction did not differ among groups. During the maintenance infusion of thiopental or propofol, respiratory resistance increased gradually across all groups. There was no difference in the response of respiratory resistance either at induction or during the 10-minute maintenance between the generic and the nongeneric propofol groups.


CONCLUSIONS
In contrast to earlier reports, this pilot study was unable to document a difference in the respiratory resistance in patients induced with thiopental or propofol. In addition, we were unable to demonstrate any different respiratory responses between generic propofol, containing sodium metabisulfite preservative, and nongeneric propofol.
Arain
Shahbaz R
SR
Department of Anesthesiology, V.A. Medical Center 112A, 5000 W. National Avenue, Milwaukee, WI 53295, USA.
Navani
Annu
A
Ebert
Thomas J
TJ
D000403:Airway Resistance / Q000187:drug effects*; D000768:Anesthesia, General; D018686:Anesthetics, Intravenous / Q000494:pharmacology*; D016535:Bronchial Hyperreactivity / Q000503:physiopathology*; D016568:Drugs, Generic / Q000494:pharmacology; D006801:Humans; D008297:Male; D008875:Middle Aged; D010366:Peak Expiratory Flow Rate; D010865:Pilot Projects; D015742:Propofol / Q000494:pharmacology*; D013874:Thiopental / Q000494:pharmacology
D018686:Anesthetics, Intravenous; D016568:Drugs, Generic; D013874:Thiopental; D015742:Propofol