Ventilator setting in ICUs: comparing a Dutch with a European cohort

BACKGROUND

From data collected during the third International Study on Mechanical Ventilation (ISMV), we compared data from a Dutch cohort with a European cohort. We hypothesised that tidal volumes were smaller and applied positive end-expiratory pressure (PEEP) was higher in the Netherlands, compared with the European cohort. We also compared use of non-invasive ventilation (NIV) and outcomes in both cohorts.

METHODS

A post-hoc analysis of a prospective observational study of patients receiving mechanical ventilation.

RESULTS

Tidal volumes were smaller (7.6 vs. 8.1 ml÷kg predicted bodyweight) in the Dutch cohort and applied PEEP was higher (8 vs. 6 cm H2O). Fewer patients admitted in the Netherlands received NIV as first mode of mechanical ventilation (7.1 vs. 16.7%). Fewer patients in the Dutch cohort developed an ICU-acquired pneumonia (4.5 vs. 12.3%, p < 0.01) and sepsis (5.7 vs. 10.9%, p = 0.03), but more patients were diagnosed as having delirium (15.8 vs. 4.6%, p < 0.01). ICU and in-hospital mortality rates were 19% and 25%, respectively, in Dutch ICUs vs. 26% and 33% in Europe (p = 0.06 and 0.03).

CONCLUSION

Tidal volumes were smaller and applied PEEP was higher in the Dutch cohort compared with international data, but both Dutch and international patients received larger tidal volumes than recommended for prevention or treatment of acute respiratory distress syndrome. NIV as first mode of mechanical ventilation is less commonly used in the Netherlands. The incidence of ICU-acquired pneumonia is lower and of delirium higher in the Netherlands compared with international data.

Isolation of a potent cholesterol nucleation-promoting activity from human gallbladder bile: role in the pathogenesis of gallstone disease

Gallbladder bile contains nucleation-promoting activity that binds to concanavalin A. The activity was found in gallbladder bile from cholesterol gallstone patients but also in gallbladder bile from patients without stones and patients with pigment stones. Bile from patients with multiple cholesterol gallstones contained high concanavalin A-binding nucleation-promoting activity. The activity was much lower in bile samples from pigment stone patients, patients without stones and patients with a solitary cholesterol stone. Serum contained very little activity and no concanavalin A-binding nucleation-promoting activity could be demonstrated in gallbladder mucosa. This suggests that concanavalin A-binding nucleation promoter is produced in the liver or bile duct epithelium. The activity was fully resistant to digestion with pronase but was heat labile and could be destroyed by prolonged incubation with a mixed glycosidase preparation indicating that sugar residues are important for this activity. On a Superose 12 gel permeation column, promoting activity eluted in two major peaks at apparent molecular weights of 150 +/- 30 kD (n = 5) and less than 5 kD respectively. The mobility on the column was not influenced by pronase digestion. The factor with the higher molecular weight could be isolated further by polyacrylamide gel electrophoresis under nondenaturing conditions. On sodium dodecyl sulfate-polyacrylamide gel electrophoresis, the apparent molecular weight of the glycoprotein was 130 kD. In conclusion, gallbladder bile contains nucleation-promoting activity that binds to concanavalin A. The activity is increased in bile from patients with multiple cholesterol gallstones and could therefore play an important role in the pathogenesis of gallstone disease.

An appraisal of the role of biliary phospholipases in the pathogenesis of gallstone disease

Human bile contains proteins that influence nucleation of cholesterol. Recently, it has been suggested that activity of phospholipases in bile may play a role in this process. To study the influence of phospholipase on nucleation we have determined the effect of phospholipases A2, C and D on the nucleation time of model bile. Phospholipase C decreased the nucleation time, whereas phospholipase A2 inhibited nucleation. The phospholipases were effective only at relatively high concentrations. Phospholipase D was strongly inhibited in model bile and probably only influenced the nucleation time by an aspecific protein effect. The cleavage products of the different phospholipases were determined in native bile samples of 14 cholesterol gallstone patients, 6 patients without stones and 4 patients with pigment stones. In all samples, choline, phosphorylcholine and free fatty acids (FFA) could be detected. However, there was no significant difference between the three groups of patients. The rate of production of choline, phosphorylcholine and FFA was measured in bile incubated at 37 degrees C. Again, there was no significant difference between the three groups of patients. We conclude that phospholipase activity in bile does not play an important role in the pathogenesis of gallstone disease.