Efficacy of non-invasive intelligent volume assured pressure support (iVAPS) and pressure support ventilation (PSV) in clinical practice.

AIMS OF THE STUDY: Noninvasive ventilation (NIV) is a well-established treatment option for hypercapnic respiratory failure; however, the best mode of ventilation remains unknown. The aim of this retrospective study was to compare patients’ adherence to NIV using either pressure support ventilation (PSV) or intelligent volume-assured pressure support (iVAPS). PATIENTS AND METHODS: In this retrospective cohort study, we assessed in- and outpatients suffering from hypercapnic respiratory failure of various aetiologies (chronic obstructive pulmonary disease [COPD], obese COPD [body mass index >30 kg/m2], obesity hypoventilation syndrome and other diseases such as amyotrophic lateral sclerosis or interstitial lung disease) after NIV initiation with PSV or iVAPS. Adherence to treatment was compared between these modes using the Wilcoxon test. Within-group differences were tested using linear regression models. Mortality and emergency hospital readmission rates were modelled using Kaplan-Meier estimates and Cox proportional hazards models. RESULTS: Adherence to treatment was similar in both groups throughout the observation period – after 6 weeks: PSV 363 min/night (interquartile range [IQR] 200–448), iVAPS 369 min/night (IQR 310–468) (p = 0.619); after 1 year: PSV 423 (323–500), iVAPS 429 (298–475) (p = 0.901); at the last follow up: PSV 481 (395–586), iVAPS 426 (391–565) (p = 0.284). NIV reduced PaCO2 significantly compared with baseline at all follow-ups: PSV −1.29/−1.49/−1.49 kPa, iVAPS −1.47/−1.23/−1.24 kPa, p <0.001 each, PSV vs iVAPS: p = 0.250, 0.756 and 0.352, respectively. Median survival time (PSV 5.06 years, iVAPS median not reached; p = 0.800) and time to first readmission (PSV 3.6 years, iVAPS 7.33 years, p = 0.200) did not differ between groups. Obese COPD patients had a longer time to hospital readmission than lean COPD patients (3.8 vs 1.5 years, hazard ratio (HR) 0.39, 95% confidence interval [CI] 0.16–0. 74; p = 0.007). Good adherence (>4 h/night and >80% nightly usage) was associated with a lower mortality rate (HR 0.34, 95% CI 0.15–0.77; p = 0.010). CONCLUSION: In a real-world setting of a mixed population with hypercapnic respiratory failure, iVAPS and PSV seem to be similarly effective in improving gas exchange and demonstrate excellent adherence to treatment. A longer survival was noted in NIV-adherent patients. Randomised controlled studies are necessary to identify patients who might benefit more from hybrid ventilation modes.

NIV by an interdisciplinary respiratory care team in severe respiratory failure in the emergency department limited to day time hours.

Non-invasive ventilatory support is frequently used in patients with severe respiratory failure (SRF), but is often limited to intensive care units (ICU). We hypothesized that an instantaneous short course of NIV (up to 2 h), limited to regular working hours as an additional therapy on the emergency department (ED) would be feasible and could improve patient´s dyspnoea measured by respiratory rate and Borg visual dyspnea scale. NIV was set up by an interdisciplinary respiratory care team. Outside these predefined hours NIV was performed in the ICU. This is an observational cohort study over 1 year in the ED in a non-university hospital. Fifty-one % of medical emergencies arrived during regular working hours (5475 of 10,718 patients). In total, 63 patients were treated with instantaneous NIV. Door to NIV in the ED was 56 (31-97) min, door to ICU outside regular working hours was 84 (57-166) min. Within 1 h of NIV, the respiratory rate decreased from 30/min (25-35) to 19/min (14-24, p < 0.001), the Borg dyspnoea scale improved from 7 (5-8) to 2 (0-3, p < 0.001). In hypercapnic patients, the blood-pH increased from 7.29 (7.24-7.33) to 7.35 (7.29-7.40) and the pCO2 dropped from 8.82 (8.13-10.15) to 7.45 (6.60-8.75) kPa. In patients with SRF of varying origin, instantaneous NIV in the ED during regular working hours was feasible in a non-university hospital setting, and rapidly and significantly alleviated dyspnoea and reduced respiratory rate. This approach proved to be useful as a bridge to the ICU as well as an efficient palliative dyspnoea treatment.

Transcutaneous versus blood carbon dioxide monitoring during acute noninvasive ventilation in the emergency department - a retrospective analysis.

QUESTIONS UNDER STUDY: Transcutaneous measurement of carbon dioxide (PtCO2) has been suggested as an alternative to invasively obtained PaCO2 for the monitoring of patients with hypercapnic respiratory failure during noninvasive ventilation (NIV). Current data on monitoring in hypoxaemic respiratory failure are scarce and show conflicting results in hypercapnic patients in the emergency department. METHODS AND SETTING: We performed a retrospective comparison of real-time PtCO2 (SenTec Digital Monitor) and arterial/venous carbon dioxide tension (PaCO2/PvCO2) measurements in patients with severe hypoxaemic and/or hypercapnic respiratory failure during NIV. Agreement between PtCO2 and PaCO2/PvCO2 was the primary endpoint. Bland-Altman analysis and linear regression were used. RESULTS: 102 patients had at least one matched measurement of PtCO2 and PaCO2/PvCO2. For patients with arterial blood gas analysis, the mean difference was 0.46 kPa at baseline (95% confidence interval [CI] 0.23 to 0.60, limits of agreement 95% CI -0.54 to 1.45) and 0.12 kPa after NIV (95% CI -0.04 to 0.29, limits of agreement 95% CI: -0.61 to 0.86). The linear regression analysis found a correlation R2 of 0.88 (p <0.001) at baseline and an R2 of 0.99 (p <0.001) after initiating NIV. For patients with venous blood gas analysis, the mean difference was 0.64 kPa at baseline (95% CI 0.04 to 1.24, limits of agreement 95% CI -0.72 to 2) and 0.80 kPa after NIV (95% CI 0.51 to 1.10, limits of agreement 95% CI 0.29 to 1.32), R2 0.78 (p <0.001) at baseline and R2 0.91 (p <0.001) after initiating NIV. A PaCO2/PvCO2 >8 kPa was associated with a lesser degree of agreement between the levels of PtCO2 and PaCO2/PvCO2 (p <0.001). CONCLUSION: Transcutaneous PCO2 monitoring shows a good concordance with PaCO2 and is a reliable, feasible, patient-friendly and safe alternative to repeated blood gas analysis for patients with severe hypoxaemic and/or hypercapnic respiratory failure receiving emergency NIV in the emergency department. An initial blood gas analysis to evaluate the respiratory and metabolic state and to rule out a significant discrepancy compared with the transcutaneous measurement is recommended.