Acute effects of intermittent hemodialysis and sustained low-efficiency hemodialysis (SLED) on the pulmonary function of patients under mechanical ventilation.

The effects of hemodialysis (HD) on pulmonary function are still controversial. The objective of this study was to evaluate the effect of intermittent hemodialysis (IHD) and sustained low-efficiency dialysis (SLED) on the respiratory mechanics of ICU patients under invasive mechanical ventilation. We prospectively studied 31 patients. Laboratory and respiratory evaluation (static and dynamic compliance and resistance) was performed pre- and post-HD. Forty HD sessions were studied and grouped in: SLED (n = 17; Qa = 200-250 mL/min, Qd = 300 mL/min) and IHD (n = 23; Qa = 250-300 mL/min, Qd = 500 mL/min). There was no difference between the groups according to age, gender, comorbidities, APACHE II, and cause of mechanical ventilation, but pre-HD, patients in the IHD group had higher levels of plasma creatinine (5.4 +/- 2.0 vs. 4.2 +/- 1.3 mg/dL, p = 0.048) and platelets (286 +/- 186 vs. 174 +/- 95 10(3)/mm(2), p = 0.032) and lower arterial pH (7.37 +/- 0.07 vs. 7.42 +/- 0.05, p = 0.02). The efficiency of the treatment was similar (p > 0.05) with both types of HD regarding fluid removal, urea reduction rate, and decrease in plasma creatinine. Pre-HD, the ventilatory conditions of both groups were similar (p > 0.05) except for pressure support ventilation and airflow resistance. There were no changes (pre- versus post-HD p > 0.05) induced either by IHD or SLED in the ratio PaO(2)/FiO(2) or in any measured ventilatory parameter. In conclusion, neither IHD nor SLED modifies the pulmonary function of patients under mechanical ventilation.