S. Ryniak et al., EFFECTS OF EXAGGERATED LITHOTOMY POSITION ON VENTILATION AND HEMODYNAMICS DURING RADICAL PERINEAL PROSTATECTOMY, Scandinavian journal of urology and nephrology, 32(3), 1998, pp. 200-203
Ventilation and haemodynamics were studied in nine anaesthetized male
patients undergoing perineal prostatectomy in the exaggerated lithotom
y position (flexed, head-down position). In the flexed head-down posit
ion, as compared to the supine position, there was a significant decre
ase in arterial oxygen tension (13.1 +/- 2.1 to 11.2 +/- 1.1 kPa, p <
0.001), a significant increase in carbon dioxide tension (4.6 +/- 5.7
to 5.7 +/- 0.2 kPa, p < 0.001) and shunt fraction (7.8 +/- 2.3 to 14.0
+/- 3.0%, p < 0.01). There were also increases in pulmonary wedge pre
ssures (11.3 +/- 2.9 to 17.9 +/- 2.9 mmHg, p < 0.01), mean pulmonary a
rtery pressures (17.6 +/- 3.8 to 25.2 +/- 3.5 mmHg, p < 0.001) and cen
tral venous pressures (11.9 +/- 2.1 to 14.7 +/- 2.8, p < 0.05). Mean a
rterial pressure fell from 92 +/- 14 to 75 +/- 10 mmHg (p < 0.05). Hea
rt rate and cardiac output were unchanged. All these changes had alrea
dy been seen but to a lesser extent when the patients were positioned
in the flexed supine position. When the patients were returned to the
supine position following surgery, arterial oxygen tension was returne
d to baseline values. Mean pulmonary artery, pulmonary capillary wedge
and central venous pressures also fell significantly. It is concluded
that the extreme exaggerated lithotomy used during surgery results in
impaired oxygenation and increased cardiac filling pressures but to a
cceptable levels in healthy anaesthetized patients. All values returne
d to normal when patient position was normalized after surgery.