To determine whether i.v.NAC has beneficial effects in patients with mild-to-moderate ALI in terms of ventilatory support(VS),FIO2 requirement-,evolution of the lung injury score(LIS),development of severe lung injury(ARDS)and mortality rate,we prospectively enrolled 61 adult patients with ALI to receive either NAC 40 mg/kg/day or Placebo(PL)during 3 days.Respiratory dysfunction was assessed daily considering the need of VS,the F102 necessary to achieve a Pa02 of 70 to 80 mmHg and the evolution of 3 components of the LIS (chest X-ray,Pa02-FIO2 ratio and respiratory system compliance).Data were collected at baseline (day 0),on the first 3 days after admission to the ICU and on discharge.NAC and PL groups(32 vs 29 patients)were comparable at entry in terms of SAPS and values of the LIS.At day 0, 69% of the patients were ventilated in the NAC group versus 76% in the PL group;at day 3, 83% of the NAC treated patients did not require any further VS, versus 52% in the PL group(p=0.01).Pa02/FIO2 improved significantly(p=0.05)from day 0 to day 3 only in the NAC group.The LIS showed a signifi cant improvement(p=0.003)in the NAC treated group within the first 10 days of treatment;no change was observed in the PL group.3 patients in each group progressed to ARDS.The one-month mortality rate was 22% for the NAC and 35% for the PL group In conclusion,early treatment with NAC seems to affect favourably pulmonary gas exchange and decrease the need for prolonged VS in patients with mild-to-moderate ALI.
In a double–blind randomised study, we examined if pretreatment with small doses of midazolam, given before anaesthesia induction with fentanyl, influences the occurrence of fentanyl–induced thoracic rigidity (FITR). At the same time, the effect of rigidity on the cardiovascular and respiratory system was assessed. Sixteen patients undergoing coronary artery bypass surgery were divided into two groups. The midazolam group (M) received 0.075 mg/kg midazolam i.v. and the placebo group (P) NaCl 0.9% 3 min before the start of fentanyl induction. During the induction period, FITR was assessed clinically on a 3–point scale. Haemodynamic and respiratory variables were collected before anaesthesia induction, at the end of the fentanyl infusion and 3 min after intubation. The incidence of FITR was high in both groups: 63% in Group M and 75% in Group P (n.s.); however, its severity was less in Group M. The appearance of rigidity affected the cardiovascular and the respiratory system: central venous and pulmonary capillary wedge pressures showed a sharp increase in patients with FITR accompanied by CO 2 retention, due to an inability to ventilate these patients adequately. We conclude that small doses of midazolam do not prevent, but may attenuate, FITR and that the appearance of rigidity causes alterations of haemodynamic and respiratory variables during induction.
