Pronóstico de una cohorte de enfermos en ventilación mecánica en 72 unidades de cuidados intensivos en España

Mechanical ventilation in Spain, 1998-2016: Epidemiology and outcomes

PURPOSE

To evaluate changes in the epidemiology of mechanical ventilation in Spain from 1998 to 2016.

DESIGN

A post hoc analysis of four cohort studies was carried out.

SETTING

A total of 138 Spanish ICUs.

PATIENTS

A sample of 4293 patients requiring invasive mechanical ventilation for more than 12h or noninvasive ventilation for more than 1h.

INTERVENTIONS

None.

VARIABLES OF INTEREST

Demographic variables, reason for mechanical ventilation, variables related to ventilatory support (ventilation mode, tidal volume, PEEP, airway pressures), complications during mechanical ventilation, duration of mechanical ventilation, ICU stay and ICU mortality.

RESULTS

There was an increase in severity (SAPSII: 43 points in 1998 vs. 47 points in 2016), changes in the reason for mechanical ventilation (decrease in chronic obstructive pulmonary disease and acute respiratory failure secondary to trauma, and increase in neurological disease and post-cardiac arrest). There was an increase in noninvasive mechanical ventilation as the first mode of ventilatory support (p<0.001). Volume control ventilation was the most commonly used mode, with increased support pressure and pressure-regulated volume-controlled ventilation. A decrease in tidal volume was observed (9ml/kg actual b.w. in 1998 and 6.6ml/kg in 2016; p<0.001) as well as an increase in PEEP (3cmH₂O in 1998 and 6cmH₂O in 2016; p<0.001). In-ICU mortality decreased (34% in 1998 and 27% in 2016; p<0.001), without geographical variability (median OR 1.43; p=0.258).

CONCLUSIONS

A significant decrease in mortality was observed in patients ventilated in Spanish ICUs. These changes in mortality could be related to modifications in ventilation strategy to minimize ventilator-induced lung injury.

Have there been changes in the application of mechanical ventilation in relation to scientific evidence? A multicenter observational study in Mexico

OBJECTIVE

The main study objectives were to describe the practice of mechanical ventilation over an 18-year period in Mexico, and estimate changes in mortality among critical patients subjected to invasive mechanical ventilation (IMV).

DESIGN

A retrospective subanalysis of a prospective observational study conducted in 1998, 2004, 2010 and 2016 was carried out.

SETTING

Intensive Care Units (ICUs) in Mexico.

PARTICIPANTS

Adult patients consecutively enrolled in the ICU during one month and who underwent IMV for more than 12hours or noninvasive mechanical ventilation for more than one hour. Follow-up was performed up to a maximum of 28 days after inclusion.

INTERVENTIONS

None.

PRINCIPAL VARIABLES OF INTEREST

Age, sex, severity upon admission as estimated by SAPS II, parameters of daily arterial blood gases, treatment and complication variables, date and status at discharge from the ICU and from hospital.

RESULTS

A total of 959 patients were included in 81 ICUs. Tidal volume (vt) decreased significantly both in patients with acute respiratory distress syndrome (ARDS) criteria (estimated 8.5ml/kg b.w. in 1998 to 6ml/kg in 2016; P<0.001) and in patients without ARDS (estimated 9ml/kg b.w. in 1998 to 6ml/kg in 2016; P<0.001). The ventilatory protective strategy (defined as vt < 6ml/kg or < 8ml/kg and a plateau pressure < 30cmH₂O) was: 19% in 1998, 44% in 2004, 58% in 2010 and 75% in 2016 (P<0.001). The adjusted mortality rate in ICU over the 4 periods was: in 2004, odds ratio (OR) 1.05 (95% confidence interval, 95%CI: 0.73-1.72; P=0.764); in 2010, OR 1.68 (95%CI: 1.13-2.48; P=0.009); in 2016, OR 0.85 (95%CI: 0.60-1.20; P=0.368).

CONCLUSIONS

The clinical practice of IMV in Mexican ICUs has been modified over a period of 18 years. The most significant change is the ventilatory strategy based on low vt. These changes have not been associated with significant changes in mortality.

Coste de oxígeno de la respiración y predicción del éxito de la desconexión de la ventilación mecánica

OBJECTIVE

To determine whether the oxygen cost of breathing (VO2 resp) may predict successful weaning from mechanical ventilation.

DESIGN

A prospective clinical study.

SETTING

A polyvalent intensive care unit of a teaching hospital.

PATIENTS

Thirty non-consecutive mechanically ventilated patients ready to wean. Successful weaning was considered when reintubation was not needed for 48 h after extubation.

INTERVENTIONS

Spontaneous breathing test with a t-tube. VO2 resp was measured with the Douglas bag method.

RESULTS

Successful weaning was present in 20 (67%) of 30 patients. No patient with successful weaning needed tracheal reintubation. A cut-off value for VO2 resp <or= 10% had the highest value for the ROC curve (0.96 +/- 0.03) and +LR (9.5; 95% CI: 1.5 - 61) and -LR (0.1; 95% CI: 0.01 - 0.4) to distinguish between success or failure of weaning. A misclassification error of 7% was present to predict successful weaning.

CONCLUSION

The oxygen cost of breathing has no clinical utility in predicting weaning outcome.

Factores asociados al pronóstico de los pacientes pediátricos ventilados mecánicamente. Un estudio internacional

OBJECTIVE

Identify factors associated with the survival of pediatric patients who are submitted to mechanical ventilation (MV) for more than 12 hours.

DESIGN

International prospective cohort study. It was performed between April 1 and May 31 1999. All patients were followed-up during 28 days or discharge to pediatric intensive care unit (PICU).

SETTING

36 PICUs from 7 countries.

PATIENTS

A total of 659 ventilated patients were enrolled but 15 patients were excluded because their vital status was unknown on discharge.

RESULTS

Overall in-UCIP mortality rate was 15,6%. Recursive partitioning and logistic regression were used and an outcome model was constructed. The variables significantly associated with mortality were: peak inspiratory pressure (PIP), acute renal failure (ARF), PRISM score and severe hypoxemia (PaO2/FiO2 < 100). The subgroup with best outcome (mortality 7%) included patients who were ventilated with a PIP < 35 cmH2O, without ARF, or PaO2/FiO2 > 100 and PRISM < 27. In patients with a mean PaO2/FiO2 < 100 during MV mortality increased to 26% (OR: 4.4; 95% CI 2.0 to 9.4). Patients with a PRISM score > 27 on admission to PICU had a mortality of 43% (OR: 9.6; 95% CI 4,2 to 25,8). Development of acute renal failure was associated with a mortality of 50% (OR: 12.7; 95% CI 6.3 to 25.7). Finally, the worst outcome (mortality 58%) was for patients with a mean PIP >/= 35 cmH2O (OR 17.3; 95% CI 8.5 to 36.3).

CONCLUSION

In a large cohort of mechanically ventilated pediatric patients we found that severity of illness at admission, high mean PIP, development of acute renal failure and severe hypoxemia over the course of MV were the factors associated with lower survival rate.