Mechanical Ventilation after Traumatic Spinal Cord Injury-A Multicentric Cohort Study-based Prediction Model for Weaning Success: The BICYCLE Score.

Rationale: Limited information exists about the epidemiology, outcomes, and predictors of weaning from mechanical ventilation in patients with spinal cord injury. Objectives: Our aim was to investigate predictors of weaning outcomes for patients with traumatic spinal cord injury (tSCI) and develop and validate a prognostic model and score for weaning success. Methods: This was a registry-based, multicentric cohort study including all adult patients with tSCI requiring mechanical ventilation (MV) and admitted to one of the intensive care units (ICUs) of the Trauma Registry at St. Michael's Hospital (Toronto, ON, Canada) and the Canadian Rick Hansen Spinal Cord Injury Registry between 2005 and 2019. The primary outcome was weaning success from MV at ICU discharge. Secondary outcomes included weaning success at Days 14 and 28, time to liberation from MV accounting for competing risk of death, and ventilator-free days at 28 and 60 days. Associations between baseline characteristics and weaning success or time to liberation from MV were measured using multivariable logistic and competing risk regressions. A parsimonious model to predict weaning success and ICU discharge was developed and validated via bootstrap. A prediction score for weaning success at ICU discharge was derived, and its discriminative ability was assessed using receiver operating characteristic curve analysis and compared with the Injury Severity Score (ISS). Results: Of 459 patients analyzed, 246 (53.6%), 302 (65.8%), and 331 (72.1%) were alive and free of MV at Day 14, Day 28, and ICU discharge, respectively; 54 (11.8%) died in the ICU. Median time to liberation from MV was 12 days. Factors associated with weaning success were Blunt injury (odds ratio [OR], 2.96; P = 0.010), ISS (OR, 0.98; P = 0.025), Complete syndrome (OR, 0.53; P = 0.009), age in Years (OR, 0.98; P = 0.003), and Cervical LEsion (OR, 0.60; P = 0.045). The BICYCLE score showed a greater area under the curve than the ISS (0.689 [95% confidence interval (CI), 0.631-0.743] vs. 0.537 [95% CI, 0.479-0.595]; P < 0.0001). Factors predicting weaning success also predicted time to liberation. Conclusions: In a large multicentric cohort, 72% of patients with tSCI were weaned and discharged alive from the ICU. Readily available admission characteristics can reasonably predict weaning success and help prognostication.

Separation from mechanical ventilation and survival after spinal cord injury: a systematic review and meta-analysis.

BACKGROUND: Prolonged need for mechanical ventilation greatly impacts life expectancy of patients after spinal cord injury (SCI). Weaning outcomes have never been systematically assessed. In this systematic review and meta-analysis, we aimed to investigate the probability of weaning success, duration of mechanical ventilation, mortality, and their predictors in mechanically ventilated patients with SCI. METHODS: We searched six databases from inception until August 2021 for randomized-controlled trials and observational studies enrolling adult patients (≥ 16 years) with SCI from any cause requiring mechanical ventilation. Titles and abstracts were screened independently by two reviewers. Full texts of the identified articles were then assessed for eligibility. Data were extracted independently and in duplicate by pairs of authors, using a standardized data collection form. Synthetic results are reported as meta-analytic means and proportions, based on random effects models. RESULTS: Thirty-nine studies (14,637 patients, mean age 43) were selected. Cervical lesions were predominant (12,717 patients had cervical lesions only, 1843 in association with other levels' lesions). Twenty-five studies were conducted in intensive care units (ICUs), 14 in rehabilitative settings. In ICU, the mean time from injury to hospitalization was 8 h [95% CI 7-9], mean duration of mechanical ventilation 27 days [20-34], probability of weaning success 63% [45-78] and mortality 8% [5-11]. Patients hospitalized in rehabilitation centres had a greater number of high-level lesions (C3 or above), were at 40 days [29-51] from injury and were ventilated for a mean of 97 days [65-128]; 82% [70-90] of them were successfully weaned, while mortality was 1% [0-19]. CONCLUSIONS: Although our study highlights the lack of uniform definition of weaning success, of clear factors associated with weaning outcomes, and of high-level evidence to guide optimal weaning in patients with SCI, it shows that around two-thirds of mechanically ventilated patients can be weaned in ICU after SCI. A substantial gain in weaning success can be obtained during rehabilitation, with additional duration of stay but minimal increase in mortality. The study is registered with PROSPERO (CRD42020156788).

Abdominal Muscle Use During Spontaneous Breathing and Cough in Patients Who Are Mechanically Ventilated: A Bi-center Ultrasound Study.

BACKGROUND: Ultrasound may be useful to assess the structure, activity, and function of the abdominal muscles in patients who are mechanically ventilated. RESEARCH QUESTION: Does measurement of abdominal muscle thickening on ultrasound in patients who are mechanically ventilated provide clinically relevant information about abdominal muscle function and weaning outcomes? STUDY DESIGN AND METHODS: This study consisted of two parts, a physiological study conducted in healthy subjects and a prospective observational study in patients who were mechanically ventilated. Abdominal muscle thickness and thickening fraction were measured during cough and expiratory efforts in 20 healthy subjects, and prior to and during a spontaneous breathing trial in 57 patients being ventilated. RESULTS: In healthy subjects, internal oblique and rectus abdominis thickening fraction correlated with pressure generated during expiratory efforts (P < .001). In patients being ventilated, abdominal muscle thickness and thickening fraction were feasible to measure in all patients, and reproducibility was moderately acceptable. During a failed spontaneous breathing trial, thickening fraction of transversus abdominis and internal oblique increased substantially from baseline (13.2% [95% CI, 0.9-24.8] and 7.2% [95% CI, 2.2-13.2], respectively). The combined thickening fraction of transversus abdominis, internal oblique, and rectus abdominis measured during cough was associated with an increased risk of reintubation or reconnection to the ventilator following attempted liberation (OR, 2.1; 95% CI, 1.1-4.4 per 10% decrease in thickening fraction). INTERPRETATION: Abdominal muscle thickening on ultrasound was correlated to the airway pressure generated by expiratory efforts. In patients who were mechanically ventilated, abdominal muscle ultrasound measurements are feasible and moderately reproducible. Among patients who passed a spontaneous breathing trial, reduced abdominal muscle thickening during cough was associated with a high risk of liberation failure. CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov; No.: NCT03567564; URL: www.clinicaltrials.gov.

Short-Term Effects of an Active Heat-and-Moisture Exchanger During Invasive Ventilation.

BACKGROUND: Humidification is a standard of care during invasive mechanical ventilation. Two types of devices are used for this purpose: heated humidifiers and heat-and-moisture exchangers (HME). AIM: To compare the short-term physiologic effects of an active HME, with those of heated humidifiers and HMEs in terms of respiratory effort, ventilatory pattern, and arterial blood gases during invasive mechanical ventilation. METHODS: We conducted a randomized crossover study with 3 different devices in 15 stable subjects who had a tracheostomy and were ventilator-dependent. Transdiaphragmatic pressure, ventilatory pattern, arterial blood gases, and dyspnea scale were recorded at baseline and at the end of a 20-min period with each device. RESULTS: Compared with heated humidifiers, the active HME was associated with higher diaphragmatic pressure-time product per minute (117.10 [interquartile range {IQR} 34.58-298.60]) versus 80.86 (IQR, 25.46-110.55) cm H2O×s/min, P = .01), higher PaCO2 (48.50 [IQR, 40.65-53.70] vs 39.60 [IQR, 37.50-49.95]) mm Hg, P = .02) and lower pH (7.41 [IQR, 7.36-7.49] vs 7.45 [IQR, 7.40-7.51], P = .030) without any significant difference in ventilatory pattern. A significantly worse dyspnea scale score (active HME, 3 (2-4) vs heated humidifiers: 4 (3-5); P = .009) was also observed. No significant differences were seen between active HME and HME. CONCLUSIONS: This study indicated that, compared with the heated humidifiers, the use of the active HME or the HME increased inspiratory effort, PaCO2 , pH, and dyspnea in stable subjects who were tracheostomized and ventilator-dependent. (ClinicalTrials.gov registration NCT02499796.).

Physiotherapy and Weaning From Prolonged Mechanical Ventilation.

BACKGROUND: Patients undergoing prolonged mechanical ventilation represent up to 15% of all patients requiring weaning from mechanical ventilation. Although recent guidelines have recommended including physiotherapy early during mechanical ventilation to speed the process of weaning, only indirect evidence supporting the use of physiotherapy is available for patients receiving prolonged mechanical ventilation. The aim of our study was to evaluate the effects of a physiotherapy program in subjects requiring prolonged mechanical ventilation and the correlates of successful weaning. METHODS: A retrospective analysis was performed on 1,313 consecutive patients admitted to a weaning unit over a 15-y period to be liberated from prolonged mechanical ventilation. Subjects underwent a program of intensive physiotherapy organized in 4 incremental steps (1-4) and were analyzed according to the steps achieved (> 2 steps or ≤ 2 steps). The rate of successful weaning was recorded, and possible predictors were considered. The 15-y period of observation was divided into 3 consecutive 5-y intervals. RESULTS: Out of 560 subjects undergoing final analysis, 349 (62.3%) were successfully weaned. The weaning success rate was significantly greater in subjects attaining > 2 steps than in subjects who attained ≤ 2 steps (72.1% vs 55.9%, respectively, odds ratio = 2.04, 95% CI = 1.42-2.96, P < .001). Stepwise logistic regression analysis showed that achievement of > 2 physiotherapy steps was the main predictor of successful weaning (odds ratio = 2.17, 95% CI = 1.48-3.23, P < .001). Underlying disease was also a predictor of successful weaning. The overall rate of successful weaning decreased, and the median duration of weaning increased, during the period of observation. CONCLUSIONS: Our data support the inclusion of physiotherapy in the management of patients requiring prolonged mechanical ventilation.