Isoflurane and desflurane impair right ventricular-pulmonary arterial coupling in dogs.
BACKGROUND
Halogenated anesthetics depress left ventricular function, but their effects on the right ventricle have been less well studied. Therefore, the authors studied the effects of isoflurane and desflurane on pulmonary arterial (PA) and right ventricular (RV) properties at baseline and in hypoxia.


METHODS
Right ventricular and PA pressures were measured by micromanometer catheters, and PA flow was measured by an ultrasonic flow probe. PA mechanics were assessed by flow-pressure relations and by impedance spectra derived from flow and pressure waves. RV contractility was assessed by end-systolic elastance (Ees), RV afterload was assessed by effective PA elastance (Ea), and RV-PA coupling efficiency was assessed by the Ees:Ea ratio. Anesthetized dogs were randomly assigned to increasing concentrations (0.5, 1, and 1.5 times the minimum alveolar concentration) of isoflurane (n = 7) or desflurane (n = 7) in hyperoxia (fraction of inspired oxygen, 0.4) and hypoxia (fraction of inspired oxygen, 0.1).


RESULTS
Isoflurane and desflurane had similar effects. During hyperoxia, both anesthetics increased PA resistance and characteristic impedance, increased Ea (isoflurane, from 0.82 to 1.44 mmHg/ml; desflurane, from 0.86 to 1.47 mmHg/ml), decreased Ees (isoflurane, from 1.09 to 0.66 mmHg/ml; desflurane, from 1.10 to 0.72 mmHg/ml), and decreased Ees:Ea (isoflurane, from 1.48 to 0.52; desflurane, from 1.52 to 0.54) in a dose-dependent manner (all P < 0.05). Hypoxia increased PA resistance, did not affect characteristic impedance, increased afterload, and increased contractility. During hypoxia, isoflurane and desflurane had similar ventricular effects as during hyperoxia.


CONCLUSIONS
Isoflurane and desflurane markedly impair RV-PA coupling efficiency in dogs, during hyperoxia and hypoxia, both by increasing RV afterload and by decreasing RV contractility.
Kerbaul
François
F
Anesthesiology, La Timone Hospital, Marseille, France.
Rondelet
Benoît
B
Motte
Sophie
S
Fesler
Pierre
P
Hubloue
Ives
I
Ewalenko
Patricia
P
Naeije
Robert
R
Brimioulle
Serge
S
D018685:Anesthetics, Inhalation / Q000633:toxicity*; D000818:Animals; D001784:Blood Gas Analysis; D000077335:Desflurane; D004285:Dogs; D006321:Heart / Q000187:drug effects*; D006352:Heart Ventricles / Q000187:drug effects; D006439:Hemodynamics / Q000187:drug effects; D018496:Hyperoxia / Q000503:physiopathology; D000860:Hypoxia / Q000503:physiopathology; D007530:Isoflurane / Q000031:analogs & derivatives* / Q000633:toxicity*; D011651:Pulmonary Artery / Q000187:drug effects* / Q000502:physiology; D014655:Vascular Resistance / Q000187:drug effects; D016278:Ventricular Function, Right / Q000187:drug effects
D018685:Anesthetics, Inhalation; D000077335:Desflurane; D007530:Isoflurane