Mechanical ventilation in Spain, 1998-2016: changes in the disconnection of mechanical ventilation

PURPOSE

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

DESIGN

Post-hoc analysis of four cohort studies.

AMBIT

138 Spanish ICUs.

PATIENTS

2141 patients scheduled extubated.

INTERVENTIONS

None.

VARIABLES OF INTEREST

Demographics, reason for mechanical ventilation, complications, methods for disconnection, failure on the first attempt at disconnection, duration of weaning, reintubation, post-reintubation tracheotomy, ICU stay and mortality.

RESULTS

There was a significant increase (p<0.001) in the use of gradual reduction of support pressure. The adjusted probability of using the gradual reduction in pressure support versus a spontaneous breathing trial has increased over time, both for the first attempt at disconnection (taking the 1998 study as a reference: odds ratio 0.99 in 2004, 0.57 in 2010 and 2.43 in 2016) and for difficult/prolonged disconnection (taking the 1998 study as a reference: odds ratio 2.29 in 2004, 1.23 in 2010 and 2.54 in 2016). The proportion of patients extubated after the first attempt at disconnection has increased over time. There is a decrease in the ventilation time dedicated to weaning (from 45% in 1998 to 36% in 2016). However, the duration in difficult/prolonged weaning has not decreased (median 3 days in all studies, p=0.435).

CONCLUSIONS

There have been significant changes in the mode of disconnection of mechanical ventilation, with a progressive increase in the use of gradual reduction of pressure support. No relevant changes in outcomes have been observed.

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.

Effect of a training programme on blood culture contamination rate in critical care

Blood culture contamination can occur from extraction to processing; its rate should not exceed 3%.

OBJECTIVE

To evaluate the impact of a training programme on the rate of contaminated blood cultures after the implementation of sample extraction recommendations based on the best evidence.

METHOD

Prospective before-after study in a polyvalent intensive care unit with 18 beds. Two phases were established (January-June 2012, October 2012-October 2015) with a training period between them. Main recommendations: sterile technique, surgical mask, double skin disinfection (70° alcohol and 2% alcoholic chlorhexidine), 70° alcohol disinfection of culture flasks and injection of samples without changing needles. Including all blood cultures of patients with extraction request.

VARIABLES

demographic, severity, pathology, reason for admission, stay and results of blood cultures (negative, positive and contaminated). Basic descriptive statistics: mean (standard deviation), median (interquartile range) and percentage (95% confidence interval). Calculated contamination rates per 100 blood cultures extracted. Bivariate analysis between periods.

RESULTS

Four hundred and eight patients were included. Eight hundred and forty-one blood cultures were taken, 33 of which were contaminated. In the demographic variables, severity, diagnosis and stay of patients with contaminated samples, no differences were observed from those with uncontaminated samples. Pre-training vs post-training contamination rates: 14 vs 5.6 per 100 blood cultures extracted (P=.00003).

CONCLUSION

An evidence-based training programme reduced the contamination of samples. It is necessary to continue working on the planning of activities and care to improve the detection of pollutants and prevent contamination of samples.

[Validating the Spanish version of the Nursing Activities Score]

INTRODUCTION

Validating workload scores ensures that they are appropriate for the purpose for which they were developed.

OBJECTIVE

To validate the Nursing Activities Score (NAS) Spanish version.

METHODOLOGY

Observational and prospective study. 1,045 patients who were admitted to a medical-surgical unit and a serious burns unit in 2006 were included. The nurse in charge assessed patient workloads by Nine Equivalent of Nursing Manpower use Score and NAS. To assess the internal consistency of the measurements of NAS, item-test correlations, Cronbach's α and Cronbach's α corrected by omitting each of the items were calculated. The intraobserver and interobserver reliability were assessed with the intraclass correlation coefficient by viewing recordings and Kappa (interobserver reliability) was estimated. For the analysis of internal validity, a factorial principal components analysis was performed. Convergent validity was assessed using the Spearman correlation coefficient values obtained from the Nine Equivalent of Nursing Manpower use Score and Spanish-NAS scales.

RESULTS

For internal consistency, 164 questionnaires were analysed and a Cronbach's α of 0.373 was calculated. The intraclass correlation coefficient for intraobserver reliability estimate was 0.837 (95% IC: 0.466-0.950) and 0.662 (95% IC: 0.033-0.882) for interobserver reliability. The estimated kappa was 0.371. For internal validity, exploratory factor analysis showed that the first item explained 58.9% of the variance of the questionnaire. For convergent validity 1006 questionnaires were included and a Spearman correlation coefficient of 0.746 was observed.

CONCLUSIONS

The psychometric properties of Spanish-NAS are acceptable.

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.

Weaning from mechanical ventilation: why are we still looking for alternative methods?

Most patients who require mechanical ventilation for longer than 24 hours, and who improve the condition leading to the indication of ventilatory support, can be weaned after passing a first spontaneous breathing test. The challenge is to improve the weaning of patients who fail that first test. We have methods that can be referred to as traditional, such as the T-tube, pressure support or synchronized intermittent mandatory ventilation (SIMV). In recent years, however, new applications of usual techniques as noninvasive ventilation, new ventilation methods such as automatic tube compensation (ATC), mandatory minute ventilation (MMV), adaptive support ventilation or automatic weaning systems based on pressure support have been described. Their possible role in weaning from mechanical ventilation among patients with difficult or prolonged weaning remains to be established.

Outcome of tracheotomized patients following reintubation

OBJECTIVE

To evaluate the outcome of tracheotomized patients after reintubation.

METHOD

Secondary analysis from a prospective, multicenter and observational study including 36 Intensive Care Units (ICUs) from 8 countries.

PATIENTS

A total of 180 patients under mechanical ventilation for more than 48 hours, extubated and reintubated within 48 hours.

INTERVENTIONS

None.

OUTCOMES

ICU mortality, length of ICU stay, organ failure.

RESULTS

Fifty-two patients (29%) underwent tracheotomy after reintubation. The median time from reintubation to tracheotomy was 2.5 days (interquartile range (IQR) 1-8 days). The length of ICU stay was significantly longer in the tracheotomy group compared with the group without tracheotomy (median time 25 days, IQR 17-43 versus 16.5 days (IQR 11-25); p<0.001). ICU mortality in the tracheotomy group was not significantly different (31% versus 27%; p 0.57).

CONCLUSIONS

In our cohort of reintubated patients, tracheotomy is a common procedure in the ICU. Patients with tracheotomy had an outcome similar to those without tracheotomy.

[Reliability of the measurement of glucose at the bedside of critical patients]

INTRODUCTION

The objective of this study is to measure the reliability of three measurement methods at the bedside of the patient, of glucose in the critical patient compared with the measurement of glucose in the central laboratory.

MATERIAL AND METHODS

Observational, perspective study developed in a polyvalent unit of 18 beds for four months. Patients who had arterial catheter were included. Eight samples obtained at the patient's bedside were compared with the plasma glucose (gold Standard): three in capillary blood, four in arterial blood and one in arterial blood gases from a syringe. The measurements at bedside were conducted with reactive strips MediSense Optium Plus and glucometer MediSense Optium. A comparison was made of the means used in the Student's T test and Bland and Altman analysis.

RESULTS

We obtained 630 samples in 70 patients. Mean glucose (SD) in mg/dl was: a) capillary samples: 149 (38), 149 (35), 147 (37); b) arterial samples: 140 (34), 142 (35), 143 (35), 142 (34); arterial gas sample syringe: 143 (33); c) plasma glucose: 138(33). There were significant differences (p < 0.001) between plasma glucose and capillary samples but not with arterial samples (p=0.2). In the arterial samples, the presence of some factors, such as vasoactive drugs, glycated solution perfusion, insulin perfusion and plasma concentration of hemoglobin, increase error and dispersion regarding the gold standard.

CONCLUSIONS

The measurement of glucose at bedside in critical patients is more reliable in arterial samples than in capillary ones.

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.

Validez de los criterios diagnósticos del síndrome de distrés respiratorio agudo

Acute respiratory distress syndrome (ARDS) is defined according to the criteria of the 1994 consensus conference. These criteria aim to <<bring clarity and uniformity to the definition of this clinical entity>>. However, the histological criteria that correspond to ARDS are the criteria of diffuse alveolar damage described in 1976 by Katzenstein et al., which are still valid at present. In the last decade, different studies have been published that have tried to correlate the clinical syndrome with the histological findings. These studies have been basically done in experimental animals, but also by the description of the pulmonary biopsy findings and post-mortem study findings. The present article aims to show discrepancy between clinical and histological diagnosis of the acute pulmonary lesion, basically having an effect on the difficulty of the ARDS diagnosis when its origin is pulmonary and the implications of this discrepancy in the clinical practice and research.

Pronóstico de los enfermos con enfermedad pulmonar obstructiva crónica reagudizada que precisan ventilación mecánica

OBJECTIVE

To determine the variables associated with prognosis for acute exacerbation of chronic obstructive pulmonary disease (AECOPD) in mechanically ventilated patients.

DESIGN

Prospective cohort study with retrospective analysis.

LOCATION

361 Intensive Care Units (ICU) in 20 countries.

PATIENTS AND METHODS

There were included in the study 522 patients who required mechanical ventilation for more than 12 hours due to an acute exacerbation of chronic obstructive pulmonary disease (AECOPD). In order to determine those variables associated with mortality, there was performed a recursive partition analysis in which the following variables were included: demographics, arterial blood gas prior to intubation, complications arising during mechanical ventilation (barotrauma, acute respiratory distress syndrome, ventilator-associated pneumonia, sepsis), organ dysfunction (cardiovascular, renal, liver, coagulation) and duration of ventilatory support.

INTERVENTIONS

None. VARIABLES OF PRIME IMPORTANCE: ICU mortality.

RESULTS

ICU and hospital mortality rates were 22% and 30%, respectively. Variables associated with mortality were cardiovascular dysfunction, renal dysfunction and duration of ventilatory support > 18 days. Median durations were as follows: mechanical ventilatory support, 4 days (P25: 2, P75: 6); weaning from ventilatory support, 2 days (P25: 1, P75: 5); stay in intensive care unit, 8 days (P25: 5, P75: 13); stay in hospital, 17 days (P25: 10, P75: 27).

CONCLUSIONS

Mortality in the studied cohort of patients with AECOPD was associated with cardiovascular dysfunction, renal dysfunction and prolonged mechanical support.