HEMODYNAMIC-CHANGES INDUCED BY 2 I E RATIOS - A TRANSESOPHAGEAL ECHOCARDIOGRAPHIC STUDY/

Purpose: To assess the effects of controlled ventilation with two I:E ratios on haemodynamic and left ventricular function in mechanically v entilated patients with moderate to severe respiratory disease, using fluctuation of the arterial pressure waveform and the changes in left ventricular areas obtained by transoesophageal echocardiography, Metho ds: Nine patients had their lungs ventilated using volume controlled v entilation with two I:E ratios (I:3 and I:1). Respiratory rate was adj usted so that six cardiac beats occurred during a respiratory cycle. S ystolic blood pressure variation (SBPV), left ventricular area variati ons measured by TEE and haemodynamic variables measured by PA catheter were compared. Results: When compared with I:E (I:3), I:E (I:1) decre ased end diastolic area (EDA) throughout-the respiratory cycle from 3% to 8% (P < 0.01) and increased SBPV from 6 +/- 1 to 11 +/- 1 mmHg (P < 0.01). In four patients, SBPV was > 12 mmHg with I:E I:1. Conversely SBPV was < 10 mmHg in all patients with I:E I:3. With I:E (I:1), EDA decreased up to 7% during expiration (P < 0.01), The ejection fraction area remained stable for both ventilatory patterns and throughout the ventilatory cycle for a given I:E. The usual invasive haemodynamic va riables were unchanged throughout the study, as was PaO2/FIO2. Conclus ion: In this setting, EDA and SBPV allow beat-to-beat evaluation of le ft ventricular preload during change of I:E ratio. Switch from I:E I:3 to I:2 may be used as a rapid, safe and reversible test to estimate i ntravascular volume status assessed by changes in SBPV or EDA.