Case report: Isoflurane therapy in a case of status asthmaticus requiring extracorporeal membrane oxygenation.

Volatile anesthetics have been described as a rescue therapy for patients with refractory status asthmaticus (SA), and the use of isoflurane for this indication has been reported since the 1980s. Much of the literature reports good outcomes when inhaled isoflurane is used as a rescue therapy for patients for refractory SA. Venovenous (VV) extracorporeal membrane oxygenation (ECMO) is a mode of mechanical circulatory support that is usually employed as a potentially lifesaving intervention in patients who have high risk of mortality, primarily for underlying pulmonary pathology. VV ECMO is usually only considered in cases where patients gas exchange cannot be satisfactorily maintained by conventional therapy and mechanical ventilation strategies. We report the novel use of isoflurane delivered systemically as treatment for severe refractory SA in a patient on VV ECMO. A 51-year-old male with a history of asthma was transferred from another institution for management of severe SA. He was intubated at the referring hospital after failing non-invasive ventilation. Initial arterial blood gas (ABG) showed pH 7.21, partial pressure of carbon dioxide (PCO2) >95 mmHg, and partial pressure of oxygen (PaO2) 60 mmHg. VV ECMO was initiated on hospital day (HD) 1 due to refractory respiratory acidosis. After ECMO initiation, acid-base status improved, however, severe bronchospasm persisted and intrinsic positive end expiratory pressure (PEEP) was measured at 18 cm H2O. Systemic paralysis was employed, respiratory rate (RR) was reduced to 4 breaths per minute. This degree of bronchospasm did not allow for ECMO weaning. On HD 5, the patient received systemic isoflurane via the ECMO circuit for 20 h. The following morning, intrinsic PEEP was 4 cm H2O, and wheezing improved. He was decannulated from VV ECMO on HD 10 and extubated on HD 17. Inhaled isoflurane therapy in patients on VV ECMO for refractory SA has shown good results, but requires delivery of the medication via anesthesia ventilators. Our case highlights an effective alternative, systemic delivery of anesthetic via the ECMO circuit, as it is often difficult and dangerous to transport these patients to the operating room (OR) or have an intensive care unit (ICU) room adjusted to accommodate an anesthesia ventilator.

Prognostic Factors for Long-Term Mortality in Critically Ill Patients Treated With Prolonged Mechanical Ventilation: A Systematic Review.

OBJECTIVES: Long-term survival for patients treated with prolonged mechanical ventilation is generally poor; however, patient-level factors associated with long-term mortality are unclear. Our objective was to systematically review the biomedical literature and synthesize data for prognostic factors that predict long-term mortality in prolonged mechanical ventilation patients. DATA SOURCES: We searched PubMed, CINAHL, and Cochrane Library from 1988 to 2015 for studies on prolonged mechanical ventilation utilizing a comprehensive strategy without language restriction. STUDY SELECTION: We included studies of adults 1) receiving mechanical ventilation for more than or equal to 14 days, 2) admitted to a ventilator weaning unit, or 3) received a tracheostomy for acute respiratory failure. We analyzed articles that used a multivariate analysis to identify patient-level factors associated with long-term mortality (≥ 6 mo from when the patient met criteria for receiving prolonged mechanical ventilation). DATA EXTRACTION: We used a standardized data collection tool and assessed study quality with a customized Newcastle-Ottawa Scale. We abstracted the strength of association between each prognostic factor and long-term mortality. Individual prognostic factors were then designated as strong, moderate, weak, or inconclusive based on an a priori previously published schema. DATA SYNTHESIS: A total of 7,411 articles underwent relevance screening; 419 underwent full article review. We identified 14 articles that contained a multivariate analysis. We abstracted 19 patient-level factors that showed association with long-term mortality. Six factors demonstrated strong strength of evidence for association with the primary outcome: age, vasopressor requirement, thrombocytopenia, preexisting kidney disease, failed ventilator liberation, and acute kidney injury ± hemodialysis requirement. All factors, except preexisting kidney disease and failed ventilator liberation, were measured at the time the patients met criteria for prolonged mechanical ventilation. CONCLUSIONS: Despite the magnitude of the public health challenge posed by the prolonged mechanical ventilation population, only 14 articles in the biomedical literature have tested patient-level factors associated with long-term mortality. Further research is needed to inform optimal patient selection for prolonged mechanical ventilation.

Long-term survival of critically ill patients treated with prolonged mechanical ventilation: a systematic review and meta-analysis.

BACKGROUND: Prolonged dependence on mechanical ventilation after critical illness is an emerging public health challenge; however, long-term outcomes are incompletely understood. We aimed to systematically analyse long-term survival of critically ill patients treated with prolonged mechanical ventilation. METHODS: We searched PubMed, CINAHL, and the Cochrane Library between 1988 and Nov 6, 2013, with no language restrictions, for studies on prolonged mechanical ventilation. We included studies of adult populations treated with mechanical ventilation for more than 14 days, who were admitted to a ventilator weaning unit, or who had a tracheostomy for acute respiratory failure. We abstracted data with a standardised collection template and assessed study quality (ie, risk of bias) using a customised Newcastle-Ottawa Scale. We did a stratified analysis based on study setting (eg, acute vs post-acute care hospitals), and used a random-effects model to calculate pooled statistics (proportions with 95% CIs) for all outcomes. We did sensitivity analyses based on study quality (ie, high-quality studies only) and country of origin (USA vs non-USA and USA vs UK). The primary outcome was mortality at 1 year. Secondary outcomes were in-hospital mortality, discharge destination among survivors, successful liberation from mechanical ventilation while in hospital, and mortality at timepoints longer than 1 year. FINDINGS: Of 6326 studies identified, 402 underwent full manuscript review, and 124 studies from 16 countries met the inclusion criteria. 39 studies reported mortality at 1 year, which was 59% (95% CI 56-62). Among the 29 high-quality studies, the pooled mortality at 1 year was 62% (95% CI 57-67). Pooled mortality at hospital discharge was 29% (95% CI 26-32). However, only 19% (16-24) were discharged to home and only 50% (47-53) were successfully liberated from mechanical ventilation. For studies in post-acute care hospitals, outcomes were worse in the USA than internationally (mortality at 1 year was 73% [95% CI 67-78] in the USA vs 47% [29-65] in non-USA countries; in-hospital mortality was 31% [26-37] vs 18% [14-24]; and liberation from ventilation was 47% [42-51] vs 63% [59-68]; p<0·0001 for all). INTERPRETATION: Although a high proportion of patients survived to hospital discharge, fewer than half of patients survived beyond 1 year. Future studies should focus on optimum patient selection for prolonged mechanical ventilation and integration of long-term outcome information into clinical decision making. FUNDING: Cooper University Health Care and Cooper Medical School of Rowan University.