Epidemiology of weaning outcome according to a new definition. The WIND study

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1 Electronic supplement Epidemiology of weaning outcome according to a new definition. The WIND study Gaëtan Béduneau 1 (MD) *; Tài Pham 2 (MD) *; Frédérique Schortgen 3 (MD); Lise Piquilloud 4 (MD); Elie Zogheib 5 (MD); Maud Jonas 6 (MD); Fabien Grelon 7 (MD); Isabelle Runge 8 (MD); Nicolas Terzi 9 (MD,PhD); Steven Grangé 10 (MD); Guillaume Barberet 11 (MD); Pierre- Gildas Guitard 12 (MD); Jean-Pierre Frat 13 (MD); Adrien Constan 14; Jean-Marie Chretien 15 (MD); Jordi Mancebo 16 (MD,PhD); Alain Mercat 17 (MD,PhD); Jean-Christophe M Richard 18 (MD,PhD); Laurent Brochard (MD,PhD) 19 for the Weaning according New Definition (WIND) study group on behalf of Réseau Européen de recherche en Ventilation Artificielle (REVA) network. *The first two authors contributed equally to this work.

2 Methods Patients and Methods This prospective multicentre observational study was endorsed by the Réseau Européen de Recherche en Ventilation Artificielle (REVA network) and included patients admitted in 36 intensive care units in France (N=29), Spain (N=6) and Switzerland (N=1) over a twelve weeks period (April 2013 to June 2013). All patients newly admitted during this period and requiring intubation for mechanical ventilation (MV) were enrolled at the date of intubation and followed until ICU discharge or day 60, whichever came first. Ethical and legal aspects This study was approved by the French Intensive Care Society (Société de Reanimation de Langue Française-SRLF) ethics committee with a waiver of consent, and as of April 9, 2013 by the Commission Nationale de l'informatique et des Libertés (CNIL), the French independent administrative authority that operates in accordance with the data protection legislation. For the centers in Switzerland and Spain, local ethics committee approval was obtained. All patients or surrogates were informed of their inclusion in this prospective study, and of the possibility to withdraw their data. Data collection Investigators had first to answer a questionnaire about their centres, including the use of sedation and weaning protocols. Participating investigators collected daily ventilation parameters and weaning strategies. Investigators recorded the weaning modalities including performance of spontaneous breathing trials (SBTs), and if so the technique used (i.e., T- piece, Low Level Pressure Support Ventilation with PSV 8 cm H 2 O and low positive endexpiratory pressure (PEEP 5 cm H 2 O), or other methods); results of SBT; extubation circumstances (i.e., planned, following a SBT or not, or self-extubation and reintubation, as E2

3 well as ICU outcome (length of MV, survival). Data collection was continued until ICU discharge or day 60 whichever occurred first. Quality control Collected data were directly downloaded as electronic files from the WIND website hosting. The electronic case report form (CRF) and the database were verified by the coordinator investigator (GB). When inconsistencies were detected, queries were sent to the investigators in order to cross-check data and solve inconsistencies. Double entries were not possible. We followed the STROBE (Strengthening The Reporting of Observational studies in Epidemiology) statement guidelines for observational cohort studies (1). Weaning classification according to the International Consensus Conference (ICC) We first applied the ICC classification (2), which defined weaning success as an extubation after a SBT and the absence of ventilator support (reintubation or noninvasive ventilation [NIV]) or death 48h following the extubation. Three weaning groups were defined based on number, timing and results of SBTs as well as extubation outcomes: simple weaning (ICC- Group 1) was defined by a successful extubation after the first SBT; difficult weaning (ICC- Group 2) was defined by a successful extubation after two to three SBTs and taking less than 7 days from the first SBT; prolonged weaning (ICC-Group 3) was defined by a successful extubation after more than three SBTs or by a weaning taking more than seven or more days after the first SBT. The new WIND definition and classification After observing the variety of practices and in order to cover the range of clinical situations encountered, we proposed an evolution of the ICC classification. This WIND classification, defined the start of weaning as any kind of separation attempt, computed the duration of this process and its prognosis, and proposed the following definitions: For intubated patients E3

4 - Separation attempt from MV: a SBT with or without extubation, or an extubation directly performed without identified SBT (whatever the type: planned, accidental or self extubation) - Successful weaning: extubation without death or reintubation within the next seven days whether post-extubation NIV was used or not, or ICU discharge without MV within 7 days, whichever comes first. For tracheostomized patients - Separation attempt from MV: a whole day or a period of several consecutive days with spontaneous ventilation through tracheostomy without any mechanical ventilation. - Successful weaning: spontaneous ventilation through tracheostomy without any mechanical ventilation during seven consecutive days or discharged with spontaneous breathing, whichever comes first. Using the separation attempt and the successful weaning definitions, the whole population was then classified into four mutually exclusive groups, based on the duration of the weaning process (i.e. delay between the first separation attempt and weaning termination): - Group no weaning, comprising patients who never experienced any separation attempt. - Group 1 (short weaning): the first attempt resulted in a termination of the weaning process within one day (successful separation or early death). - Group 2 (difficult weaning): the separation was completed after more than one day but in less than one week after the first separation attempt (successful weaning or death). - Group 3 (prolonged weaning): weaning was still not terminated 7 days after the first separation attempt (by success or death). E4

5 This last group was further split in two subgroups: Group 3a (prolonged weaning leading to a weaning success): successful weaning after seven days or more after the first attempt; Group 3b (prolonged weaning without success). "The new WIND definition and classification". The new "WIND classification", an evolution of the ICC classification, was elaborated after the first results of the study describing various clinical practice, in particular concerning lack of use of SBT, use of NIV, the presence of tracheostomised patients, etc. The steering committee met (GaB, TP, FS, JCR, JM, AM and LB) to formulate proposal which would allow to classify all patients. The goal was to take into account the variety of clinical practice and to maximize the number of patients classified. We therefore proposed a priori simplified and pragmatic definitions based on the duration of the process that could be operational in any institution. We considered useful to clearly identify patients with no separation attempt from patients who entered the weaning process, including those for which a weaning of MV was unsuccessful or leading to death. This allowed to classify all the patients, which may be important for future research and quality improvement programs about weaning from MV. An important change was the definition of separation attempts that brought together all the situations leading to extubation: a formal SBT as well as an extubation without SBT. Indeed, clinicians may not want to perform SBT before extubation when the likelihood of success is very high, such as scheduled post-operative conditions or non-complicated drug overdose with coma. We modified the definition of the weaning success to seven days, to take into account the frequent use of noninvasive ventilation that may prolong the time before reintubation. Postextubation noninvasive ventilation is widely used and could actually modify post-extubation E5

6 evolution, with the possibility to increase the time at which success or failure can be defined, leading several authors to propose a delay of seven days to define extubation success (3, 4). Weaning definitions in tracheostomized patients raised specific issues: these patients were not defined in the ICC groups and have been often excluded from the weaning studies (5, 6). Previous studies defined weaning success in tracheostomized patients as spontaneous breathing trough the tracheal cannula or directly through the tracheostoma for 48 hours (7, 8) to five days (9). We here used a time threshold of seven days to be consistent with the extubation success definition and with the consensus conference on the management of patients requiring prolonged mechanical ventilation (10). We then tested whether these definitions could be applied and further discussed all ambiguous cases. The final model was then applied and the results analyzed. Use of sedation and weaning protocols, and use of SBT We assessed the association between the presence of protocols for sedation or for weaning and the likelihood of having a short phase of separation or short weaning. For this analysis, patients with limitations decisions were excluded in order not to consider patients who had an end of life extubation as having a short weaning. We compared patients whose first separation attempt was a SBT to patients who had another type of first separation attempt. We restricted the group of patients without SBT to those who had a planned extubation without SBT and no limitation decision (e-table 4). Statistical analysis: Descriptive statistics included frequency (percentages) for categorical variables, mean and standard deviation or median and interquartile ranges (IQR) for continuous variables. Comparisons of proportions were made using Chi2 or exact Fisher tests and continuous variables were compared using Student t-test or Wilcoxon rank sum test as appropriate. E6

7 We performed a multivariable analysis of factors associated with simple weaning by means of a logistic regression, forcing both sedation and weaning protocols in the final model. Last, we performed a multivariable logistic regression to assess factors associated with the use of a SBT before a planned extubation. All statistical tests were two-sided. Two-sided P values of 0.05 or less were considered statistically significant. Statistical analyses were performed with R ( software packages. Bibliography 1. von Elm E, Altman DG, Egger M, Pocock SJ, Gøtzsche PC, Vandenbroucke JP. The Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) statement: guidelines for reporting observational studies. PLoS Med 2007;4:e Boles J-M, Bion J, Connors A, Herridge M, Marsh B, Melot C, Pearl R, Silverman H, Stanchina M, Vieillard-Baron A, Welte T. Weaning from mechanical ventilation. Eur Respir J 2007;29: Thille AW, Richard J-CM, Brochard L. The decision to extubate in the intensive care unit. Am J Respir Crit Care Med 2013;187: Girault C, Bubenheim M, Abroug F, Diehl JL, Elatrous S, Beuret P, Richecoeur J, L Her E, Hilbert G, Capellier G, Rabbat A, Besbes M, Guérin C, Guiot P, Bénichou J, Bonmarchand G, VENISE Trial Group. Noninvasive ventilation and weaning in patients with chronic hypercapnic respiratory failure: a randomized multicenter trial. Am J Respir Crit Care Med 2011;184: E7

8 5. Pu L, Zhu B, Jiang L, Du B, Zhu X, Li A, Li G, He Z, Chen W, Ma P, Jia J, Xu Y, Zhou J, Qin L, Zhan Q, Li W, Jiang Q, Wang M, Lou R, Xi X. Weaning critically ill patients from mechanical ventilation: A prospective cohort study. J Crit Care 2015;30:862.e Wang J, Ma Y, Fang Q. Extubation with or without spontaneous breathing trial. Crit Care Nurse 2013;33: Sellares J, Ferrer M, Cano E, Loureiro H, Valencia M, Torres A. Predictors of prolonged weaning and survival during ventilator weaning in a respiratory ICU. Intensive Care Med 2011;37: Funk G-C, Anders S, Breyer M-K, Burghuber OC, Edelmann G, Heindl W, Hinterholzer G, Kohansal R, Schuster R, Schwarzmaier-D Assie A, Valentin A, Hartl S. Incidence and outcome of weaning from mechanical ventilation according to new categories. Eur Respir J 2010;35: Jubran A, Grant BJB, Duffner LA, Collins EG, Lanuza DM, Hoffman LA, Tobin MJ. Effect of pressure support vs unassisted breathing through a tracheostomy collar on weaning duration in patients requiring prolonged mechanical ventilation: a randomized trial. JAMA 2013;309: MacIntyre NR, Epstein SK, Carson S, Scheinhorn D, Christopher K, Muldoon S, National Association for Medical Direction of Respiratory Care. Management of patients requiring prolonged mechanical ventilation: report of a NAMDRC consensus conference. Chest 2005;128: E8

9 E-TABLES TABLE E1: Characteristics of the group 3 including comparison between group 3a and group 3b G3 (All) N=235 G3a N=145 G3b N=90 Age, years 65±13 64 ±14 67±12 Sex M/F SAPS II at admission, points 53±18 52 ±19 55±17 SOFA at admission, points SOFA at Day 3 Admission type Medical Planned surgery Unplanned surgery 8.1± ± (78.7%) 18 (7.7%) 32 (13.6%) 7.7± ± (80.0%) 10 (6.9%) 19 (13.1%) 8.8± ± (76.7%) 8 (8.9%) 13 (14.4%) Cardiac Abdominal Vascular Neuro Urologic Thoracic Trauma Head & Neck Others 10 (4.3%) 14 (6.0%) 9 (3.8%) 5 (2.1%) 1 (0.4%) 6 (2.6%) 2 (0.9%) 0 (0.0%) 3 (1.3%) 3 (2.1%) 8 (5.5%) 6 (4.1%) 5 (3.5%) 1 (0.7%) 2 (1.4%) 2 (1.4%) 2 (1.4%) 7 (7.8%) 6 (6.7%) 3 (3.3%) 0 4 (4.4%) 1 (1.1%) Total number of days of invasive MV, days Ventilator free days 1, days Delay from intubation to 1 st SA Length of stay in the ICU, days Length of stay in the ICU in survivors, days Status at ICU discharge (or D60) Dead 19 [15;31] 0 [0;12] 6 [3;10] 31 [20;46] 37 [23;52] 70 (29.8%) 17 [14;28] 11 [0;14] 7 [3;10] 34 [22;47] 34 [21;47] 3 (2.1%) 23 [16;38] 0 [0;0] 6 [3;10] 28 [17;42] 56 [33;60] 67 (74.4%) Alive and weaned - Spontaneous breathing - NIV - Tracheostomy (permanent spontaneous breathing) 140 (59.6%) 96 (40.9%) 10 (4.3%) 34 (14.5%) 140 (96.6%) 96 (66.2%) 10 (6.9%) 34 (23.4%) Alive and Invasive ventilation - Tube - Tracheostomy with mechanical ventilation Decision of withholding or withdrawing invasive MV: - Total - Among deceased patients - Among survivors 25 (10.6%) 5 (2.1%) 20 (8.5%) 63 (26.8%) 42 (60.0%) 21 (12.7%) 2 (1.4%) 2 (1.4%) 23 (16.0%) 3 (100%) 20 (14.1%) 29 (30.2%) 9 (9.4%) 20 (20.8%) 40 (41.7%) 39 (58.2%) 1 (3.5%) Abbreviations: MV: mechanical ventilation; SA: separation attempt; ICU: intensive care unit; NIV: noninvasive ventilation; SD: standard deviation; IQR: interquartile range 1 Ventilation free days (VFD) = 28 minus the total number of days with Invasive MV E9

10 TABLE E2: Comparison consensus conference classifications and the new WIND classification Consensus Agreement (%) Wind Conference Not classified TOTAL Classification NW NA % % % TOTAL (N) Agreement (%) 98.2% 45.8% 55.0% NA 42.3 % For each line and each column, agreement was calculated as follow: E10

11 TABLE E3: Characteristics of separation attempt and weaning according to the weaning group, data are presented as mean ±SD, median [IQR] or N (%) Total Number of SA Number of SA per patient Type of SA, n (%): T-tube LPSV Extubation without SBT Self extubation Planned extubation despite SBT failure Other type of SBT Continuous period of spontaneous breathing during tracheostomy GO N=658 G1 N= * 1 [1;1] 662 (37.4%) 702 (39.7%) 237 (13.4%) 109 (6.2%) 9 (0.5%) 36 (2.0%) 14 (0.8%) G2 N= [2;3] 399 (52.1%) 291 (38.0%) 24 (3.1%) 22 (2.9%) 6 (0.8%) 14 (1.9%) 10 (1.3%) G3 All N= [2;5] 387 (41.3%) 386 (41.4%) 37 (4.0%) 35 (3.7%) 2 (0.2%) 27 (2.9%) 62 (6.6%) G3a N= [2;5] 270 (42.3%) 244 (38.2%) 23 (3.6%) 22 (3.4%) 18 (2.8%) 61 (9.6%) G3b N= [1;4] 117 (39.3%) 142 (47.7%) 14 (4.7%) 13 (4.4%) 2 (0.7%) 9 (3.0%) 1 (0.3%) Total Number of extubations Number of extubations per patient 1542** 1 [1;1] [1;1] [1;2] [1;2] 87 1 [0;1] No of days with invasive MV 3 [2;7] 3 [2;6] 9 [6;13] 19 [15;31] 17 [14;28] 23 [16;38] Delay from intubation to first weaning attempt, days 3 [2;5] 6 [3;10] 6 [3;10] 7 [3;10] 6 [3;10] Delay from intubation to first successful extubation, days 3 [2;5] 9 [7;13] 16 [12;22] 16 [12;22] No of patients with pressure support before first SBT or first extubation, n 973 (63.1%) 215 (78.8%) 179 (76.2%) 111 (76.6%) 68 (75.6%) Pressure support before first SBT or first extubation, days 1 [0;2] 2 [1;4] 2 [1;4] 2 [1;4] 2 [1;4] Patients with planned extubation after SBT success, n 1179 (76.4%) 226 (82.8%) 160 (68.1%) 115 (79.3%) 45 (50.0%) Patients with self extubation, n Patients with self extubation only (i.e. no planned extubation) 107 (6.9%) 103 (6.7%) 21 (7.7%) 10 (3.7%) 33 (14.0%) 11 (4.7%) 21 (14.5%) 3 (2.1%) 12 (13.3%) 8 (8.9%) Patients with reintubation, n 0 70 (25.6%) 148 (63.0%) 94 (64.8%) 54 (60.0%) Patients receiving post extubation NIV, n 202 (13.1%) 47 (17.2%) 59 (25.1%) 39 (26.9%) 20 (22.2%) Patient with do not reintubate order, n 117 (17.8%) 130 (8.4%) 46 (16.8%) 63 (26.8%) 23 (15.9%) 40 (44.4%) Abbreviations: SA: separation attempt; LPSV: Low Level Pressure Support Ventilation; SBT: Spontaneous Breathing Trial; MV: mechanical ventilation; NIV: noninvasive ventilation; SD: standard deviation; IQR: interquartile range * More SA than patients because of possibility of several SA in 24h ** 17 patients were never extubated : one died after the 1 st SA, 14 were tracheotomised before any SA and then were weaned, 2 were discharged with invasive MV within 24h after their 1 st SA E11

12 Table E4: Type separation attempt among the 382 patients whose first separation attempt was not a SBT Type of separation attempt N (%) Planned extubation without SBT 252 (55.6%) Self-extubations 124 (27.3%), Separation attempt while tracheostomized 30 (6.6%) SBT after their first Separation attempt 48 (10.6%) Total 454 (100%) E12

13 Figure E1: Distribution of Ventilator free days at day 28 according to weaning groups (absolute numbers) This figure shows for each group and for the whole population, the number of patients achieving each number of ventilator free days from 27 to 0. Ventilator free days are defined by 28 minus the total number of days with Invasive Mechanical Ventilation. Non survivors were considered as having 0 Ventilator free days. E13