Introduction: Positive pressure ventilation influences hemodynamics and impairs renal function. The effects of inverse ratio ventilation (IRV) on hormonal response and renal function need to be investigated because this represents a highly invasive form of positive pressure ventilation.
Materials and methods: Ten male patients were treated postoperatively for 60 min using five different ventilation modes. At the end of these periods, hemodynamics, urine production, fractional excretion of sodium (FESo), as well as the hormones, atrial natriuretic peptide (ANP), renin, angiotensin II, aldosterone, and antidiuretic hormone (ADH), were measured in plasma.
Results: Central venous pressure (CVP), ADH, and renin with a positive end-expiratory pressure (PEEP) of 15 cm H(2)O and an inspiration/expiration ratio (I:E) of 1:2 revealed significant increases from baseline, whereas CVP, renin, and FESo showed an increase with an PEEP of 15 cm H(2)O and an I:E ratio of 2:1. Urine production significantly decreased with an PEEP of 15 cm H(2)O and an I:E ratio of 2:1.
Conclusions: IRV with PEEP induced clear effects on hemodynamics and hormonal responses (renin) as well as a decrease in urine production in patients with healthy renal and pulmonary systems after an operation. However, all parameters apart from FESo and renin remained within the normal range. Whether pathological values are also observed after longer periods of positive pressure ventilation shall be the subject of other studies.