Volatile anaesthetics and positive pressure ventilation reduce left atrial performance: a transthoracic echocardiographic study in young healthy adults.

BACKGROUND

Animal and in vitro studies suggest that volatile anaesthetics affect left atrial (LA) performance. We hypothesized that human LA pump function and dimensions are altered by volatile anaesthetics in vivo.

METHODS

We performed transthoracic echocardiographic (TTE) measurements in 59 healthy subjects (aged 18-48 yr) undergoing minor surgery under general anaesthesia. The unpremedicated patients were randomly assigned to anaesthesia with sevoflurane, desflurane, or isoflurane. TTE examinations were performed at baseline and after induction of anaesthesia and upon placement of a laryngeal mask during spontaneous breathing. After changing to intermittent positive pressure ventilation (IPPV), an additional TTE was performed. The study focused on the velocity-time integral of late peak transmitral inflow velocity (AVTI) and maximum LA volume.

RESULTS

We found no evidence for relevant differences in the effects of the three volatile anaesthetics. AVTI decreased significantly from 4.1 (1.2) cm at baseline to 3.2 (1.1) cm during spontaneous breathing of 1 minimum alveolar concentration of volatile anaesthetics. AVTI decreased further to 2.8 (1.0) cm after changing to IPPV. The maximum LA volume was 45.4 (18.6) cm(3) at baseline and remained unchanged during spontaneous breathing but decreased to 34.5 (16.7) cm(3) during IPPV. Other parameters of LA pump function and dimensions decreased similarly.

CONCLUSIONS

Volatile anaesthetics reduced active LA pump function in humans in vivo. Addition of IPPV decreased LA dimensions and further reduced LA pump function. Effects in vivo were less pronounced than previously found in in vitro and animal studies. Further studies are warranted to evaluate the clinical implications of these findings.

CLINICAL TRIAL REGISTRATION

NCT0024451.