[Fatal or near-fatal asthma: clinical entity or incorrect management?]

Extracorporeal membrane oxygenation for life-threatening asthma refractory to mechanical ventilation: analysis of the Extracorporeal Life Support Organization registry

Background

The use of extracorporeal membrane oxygenation (ECMO) in cases of near-fatal asthma (NFA) has increased, but the benefits and potential complications of this therapy have yet to be fully investigated.

Methods

Cases were extracted from the Extracorporeal Life Support Organization Registry between March 1992 and March 2016. All patients with a diagnosis of asthma (according to the International Classification of Diseases 9th edition), who also received ECMO, were extracted. Exclusion criteria included patients who underwent multiple courses of ECMO; those who received ECMO for cardiopulmonary resuscitation or cardiac dysfunction; and those with another primary diagnosis, such as sepsis. We analyzed survival to hospital discharge, complications, and clinical factors associated with in-hospital mortality, in patients with severe life-threatening NFA requiring ECMO support.

Results

In total 272 patients were included. The mean time spent on ECMO was 176.4 hours. Ventilator settings, including rate, fraction of inspired oxygen (FiO₂), peak inspiratory pressure (PIP), and mean airway pressure, significantly improved after ECMO initiation (rate (breaths/min), 19.0 vs. 11.3, p < 0.001; FiO₂ (%), 81.2 vs. 48.8, p < 0.001; PIP (cmH₂O), 38.2 vs. 25.0, p < 0.001; mean airway pressure (cmH₂O): 21.4 vs. 14.2, p < 0.001). In particular, driving pressure was significantly decreased after ECMO support (29.5 vs. 16.8 cmH₂O, p < 0.001). The weaning success rate was 86.7%, and the rate of survival to hospital discharge was 83.5%. The total complication rate was 65.1%, with hemorrhagic complications being the most common (28.3%). Other complications included renal (26.8%), cardiovascular (26.1%), mechanical (24.6%), metabolic (22.4%), infection (16.5%), neurologic (4.8%), and limb ischemia (2.6%). Of the hemorrhagic complications, cannulation site hemorrhage was the most common (13.6%). Using multivariate logistic regression analysis, it was found that hemorrhage was associated with increased in-hospital mortality (odds ratio, 2.97; 95% confidence interval, 1.07–8.24; p = 0.036). Hemorrhage-induced death occurred in four patients (1.5%). The most common reason for death was organ failure (37.8%).

Conclusions

ECMO can provide adequate gas exchange and prevent lung injury induced by mechanical ventilation, and may be an effective bridging strategy to avoid aggressive ventilation in refractory NFA. However, careful management is required to avoid complications.

Electronic supplementary material

The online version of this article (doi:10.1186/s13054-017-1886-8) contains supplementary material, which is available to authorized users.

Asthma mortality in Puerto Rico: 1980-2007

BACKGROUND

Asthma is a highly prevalent chronic disease. Prevalence and mortality are particularly high in Puerto Ricans living in the United States as compared with other populations.

OBJECTIVE

To determine asthma mortality rates in Puerto Rico (1980-2007) and to assess the sociodemographic variables that may be associated with these rates.

METHODS

Data were obtained from the Vital Statistics Office at the Puerto Rico Department of Health. Crude mortality rates (CMRs) and their 95% confidence intervals (95% CIs) were used to evaluate differences between age groups and across years. Mortality risk ratios (RRs) by sociodemographic variables were estimated using generalized lineal models with a Poisson link function to identify at-risk groups.

RESULTS

During the study period, there were 4232 deaths recorded with asthma as the cause of death. From 1980 to 1998, annual asthma mortality rates fluctuated between 3.32 and 6.56 deaths per 100,000 (mean 4.77), followed by a decline after implementation of the ICD-10 for reporting cause of death in 1999. Between 1999 and 2007, the mean asthma death rate declined to 3.01 (4.89 in 1999 to 2.02 in 2007). Overall, asthma mortality rates were between 1.77 and 4.0 times higher in Puerto Rico than in the United States. Throughout the whole study period, mortality rates were higher in older age groups. In addition, the adjusted regression model for asthma deaths showed that persons divorced or widowed, and persons with only elementary education had significantly higher risk of asthma mortality than their counterparts.

CONCLUSION

Asthma death rates were higher in Puerto Rico than in the United States general population. Although asthma mortality in Puerto Rico declined, rates continued to be significantly higher than those recorded in the United States. There was a progressive decline in asthma mortality rates after 1999 that may be explained by changes in reporting classification, increased use of corticosteroids, and improved asthma awareness. After controlling for possible confounding variables, age and elementary education were found to increase the risk of mortality due to asthma among Puerto Ricans.