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Weaning ventilator

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Weaning ventilator

  2. 2. BACK TO THE BASIC… • Indications for intubation • Indications for mechanical ventilation • Weaning ventilator strategies • Extubation • Journal club: Pressure support VS T-piece during SBT on successful extubation
  3. 3. INDICATIONS FOR INTUBATION: 4P • Airway protection • Assist ventilation (positive pressure) • Prevent aspiration • Suction secretion (pulmonary toilet)
  4. 4. INDICATIONS FOR MECHANICAL VENTILATION • Patients unable to oxygenate without high FiO2 or CPAP • Patients unable to do the work of breathing without mechanical ventilation Wilson WC, Grande CM, Hoyt DB. Trauma critical care. New York: Informa Healthcare, 2007.
  5. 5. Wilson WC, Grande CM, Hoyt DB. Trauma critical care. New York: Informa Healthcare, 2007. Davidson C, Treacher D. Respiratory Critical Care. London: Arnolds, 2002.
  6. 6. WEANING VENTILATION STRATEGIES 1. Clinically stable: • Central nervous system: normal CNS function, no sedation • Cardiovascular system: hemodynamically stable • Respiratory system: FiO2 0.4, PEEP 5 cmH2O, O2 sat > 92: 2. Spontaneous breathing trial (SBT) 3. Assess weaning parameter: rapid shallow breathing index (RSBI) 4. Assess extubation parameter: cuff leak test 5. extubation Wilson WC, Grande CM, Hoyt DB. Trauma critical care. New York: Informa Healthcare, 2007. Davidson C, Treacher D. Respiratory Critical Care. London: Arnolds, 2002.
  7. 7. WEANING VENTILATION STRATEGIES: SBT • T-piece 2 h • SIMV mode • PSV mode: reduce PS until 5 - 8 cmH2O Wilson WC, Grande CM, Hoyt DB. Trauma critical care. New York: Informa Healthcare, 2007. Davidson C, Treacher D. Respiratory Critical Care. London: Arnolds, 2002.
  8. 8. WEANING VENTILATION STRATEGIES: RSBI • RSBI = RR (bpm) / tidal volume (L) • RSBI < 100-105 b/L predicts successful extubation (accuracy 85%) Wilson WC, Grande CM, Hoyt DB. Trauma critical care. New York: Informa Healthcare, 2007. Davidson C, Treacher D. Respiratory Critical Care. London: Arnolds, 2002.
  9. 9. EXTUBATION STRATEGIES • Assess risk factors for postextubation stridor: airway edema, vocal cords ulcer and cyst, RLN injury • evaluation of periglottic swelling: • Cuff-leak test • Fiberoptic bronchoscopy • Imaging study: laryngeal ultrasound Wilson WC, Grande CM, Hoyt DB. Trauma critical care. New York: Informa Healthcare, 2007. Davidson C, Treacher D. Respiratory Critical Care. London: Arnolds, 2002.
  10. 10. EXTUBATION STRATEGIES: CUFF-LEAK TEST • ATS recommend cuff-leak test in high risk of postextubation stridor • if failed, administer systemic steroids for at least 4 hours before extubation • Positive cuff-leak test is defined by < 110 ml of different between exhaled volume • before cuff deflation • After cuff deflation Cuff Leak Test for the Diagnosis of Post-Extubation Stridor: A Multicenter Evaluation Study. Journal of intensive care medicine. 2019: 34(5):391- 396.
  11. 11. JAMA June 11, 2019 Volume 321, Number
  12. 12. INTRODUCTION • Daily screening of respiratory function by SBT decreases ventilation duration • After SBT and extubation, 10 – 25% require reintubation  higher morbidity • Most common modes of SBT are T-piece and PSV, 30 minutes to 2 hours • No evidence: which one has a higher successful extubation rate • This study compared between: • More demanding T-piece for 2 hour • Less demanding PSV 8 cmH2O for 30 minutes
  13. 13. METHODS • From January 2016 through April 2017 • 18 Spanish intensive care units: multicenter randomized clinical trial • Approved by ethic committee of each hospital • All patients were informed consent
  14. 14. METHODS • Inclusion criteria: • Patients at 18 years or older • Undergoing mechanical ventilation at least 24 hours • Fulfilled weaning criteria • Exclusion criteria: • Patients with tracheostomies • Patients with do-not-reintubate orders
  15. 15. METHODS: WEANING CRITERIA • Improvement of condition leading to intubation • Hemodynamically stable: SBP 90-160 mmHg, HR < 140/min, no or low dose vasopressors • GCS ≥ 13 • Respiratory stability: O2sat > 90%, FiO2 ≤ 0.4, RR < 35/min, spontaneous TV > 5 ml/kg, RR/TV < 100 beat/L, maximal Pi > 15 cmH2O • Noncopious secretion: < 3 aspiration in last 8 hours
  16. 16. METHODS: RANDOMIZATION • 1:1 ratio • means of tables of computer-generated random numbers in blinded blocks of 4 patients for each center. • A central administrator who was not involved in the analyses used an opaque envelope to allocate patients to receive one of the two treatments • The intervention was not blinded for the investigators or attending physicians
  17. 17. METHODS: INTERVENTIONS • Before randomization, physicians decide on extubation strategy (whether to reconnect the patient to the ventilator for 1 hour before extubation and whether to administer noninvasive ventilation or high- flow nasal cannula after extubation) • Patients randomized to • Highly demand 2-hr T-piece • Less demand PSV 8 cmH2O and PEEP 0 • Patients were extubated after successful SBT • No ABG was required but if so, the results were recorded
  18. 18. METHODS: INTERVENTIONS • Physicians record dyspnea using Borg dyspnea scale • 0 – 10 • 0 = no dyspnea • 10 = maximal dyspnea • Ask at the beginning and end of SBT, and without ventilator
  19. 19. METHODS: INTERVENTIONS • If not tolerate SBT  back to ventilator with these failure criteria: • agitation, anxiety • low level of consciousness(Glasgow Coma Scale score <13) • respiratory rate higher than 35/min and/or use of accessory muscles • oxygen saturation by pulse oximetry less than 90% with FiO2 higher than 0.5 • heart rate higher than 140/min or greater than a 20% increase from baseline • systolic blood pressure lower than 90 mm Hg • development of arrhythmia
  20. 20. METHODS: INTERVENTIONS • Additional SBTs were not protocolized, and mode and duration were left to the discretion of attending teams • Respiratory failure within 72 hours of extubation was defined as the occurrence of at least 1 of the following: • respiratory acidosis with pH lower than 7.32 and PaCO2 higher than 45 mm Hg • oxygen saturation less than 90% with FiO2 higher than 0.5 • respiratory rate higher than 35/min • low level of consciousness (Glasgow Coma Scale score <13) • severe agitation • clinical signs of respiratory fatigue.
  21. 21. METHODS: INTERVENTIONS • Treatment of postextubation respiratory failure was not protocolized • When noninvasive ventilation was used, duration, maximum inspiratory and expiratory pressures, and maximum FiO2 were recorded • When respiratory failure was treated with a high flow nasal cannula, duration, maximum flow, and maximum FiO2 were recorded • Patients needing reintubation within 72 hours were NOT randomized again for weaning, but the need for tracheostomy and the date of final liberation from mechanical ventilation were registered
  22. 22. METHODS: OUTCOMES • primary outcome: successful extubation  free of invasive mechanical ventilation 72 hours after the first SBT • Secondary outcomes: • rate of reintubation • ICU and hospital lengths of stay • hospital and 90-day mortality
  23. 23. METHODS: OUTCOMES • Exploratory outcomes: • time to reintubation and reasons for reintubation • Incidence of tracheostomy • Use of noninvasive ventilation and high-flow nasal cannula as prophylaxis against postextubation respiratory failure and to treat it.
  24. 24. METHODS: OUTCOMES • Post hoc outcomes: • ICU mortality • Borg Dyspnea Scale score at the end of the SBT • patients’ confidence in their ability to breathe without the ventilator • arterial blood analysis after successful SBT
  25. 25. METHODS: STATISTICAL ANALYSIS • a successful extubation rate of 75% and an absolute increase in successful extubation of 7% were expected  required sample for an α=.05 and a power of 80% was estimated to be 540 patients in each group • Using intention-to-treat principle with no exclusion after randomization • Patients extubated outside of protocol were analyzed as having a failed SBT • No participants were excluded from main or secondary analyses because of missing or incomplete data. • Reintubation was recorded only among patients who completed the trial
  26. 26. METHODS: STATISTICAL ANALYSIS • Categorical variables are presented as absolute and relative frequencies. • Continuous variables are summarized as medians and interquartile ranges (IQRs) for nonnormal distributions • The Mann-Whitney U was used for nonparametric continuous variables • To compare categorical variables, the 2χ test was used, except when expected frequencies in contingency tables were less than 5, in which case the Fisher exact test or the Monte Carlo method was used
  27. 27. METHODS: STATISTICAL ANALYSIS • Time-to-event outcomes were analyzed with Kaplan Meier curves and compared by log-rank test • For the time-to event outcome of 72-hour successful extubation • deaths occurring before 72 hours were introduced in the survival analysis as censored data • Event or censored times for all patients were calculated from the time of randomization. • Crude hazard ratios and 95% confidence intervals were calculated using a univariable Cox proportional regression model to estimate the effect size of randomization group • Proportionality of hazards was verified by examining Schoenfeld residual plots
  28. 28. METHODS: STATISTICAL ANALYSIS • A post hoc random-effects multilevel logistic regression model was used to determine variables associatedwith 72-hour successful extubation, taking into account the effect of hospital • Patient characteristics that were associated with 72-hour successful extubation in the bivariable analysis were introduced in the random-effects multilevel logistic regression model as first- level variables andhospital as a second-level variable (random effect)
  29. 29. METHODS: STATISTICAL ANALYSIS • Odds ratios (ORs) and median ORs with 95% confidence intervals were used to measure the association between each covariate and 72-hour successful extubation. • The median OR is a measure of the variation between rates of 72-hour successful extubation at different hospitals that is unexplained by the modeled risk factors  defined as the median of the set of ORs that could be obtained by comparing 2 patients with identical patient-level characteristics from 2 randomly chosen hospitals
  30. 30. • Covariates were introduced in the random-effects multilevel logistic regression model using a researcher-controlled backward exclusion strategy • Post hoc analyses were performed for primary, secondary, exploratory, and post hoc outcomes among the following populations: • patients extubated after the first SBT • patients extubated outside of protocol • patients treated per protocol • several subgroups defined by baseline demographic characteristics METHODS: STATISTICAL ANALYSIS
  31. 31. • Effect sizes were evaluated by computing absolute risk differences with 95% confidence intervals for binary outcomes and differences in means with 95% confidence intervals for continuous outcomes. • Figures were plotted for unadjusted risk ratios and 95% confidence intervals in the subgroup analysis by • age • days of mechanical ventilation • APACHE II score • Chronic obstructive pulmonary disease (COPD) • medical, surgical, or trauma admission • No tests for interaction were conducted for the subgroup analyses METHODS: STATISTICAL ANALYSIS
  32. 32. • A 2-sided α=.05 was considered statistically significant • Data were analyzed using SPSS version 22(IBM Corp) and Stata version 14 (StataCorp) • Subgroup analysis graphs were generated using R version 3.5.2 (R Foundation for Statistical Computing) • There was no adjustment for multiple comparisons • Results of the subgroup analyses and the analyses for secondary and exploratory outcomes should be interpreted as exploratory METHODS: STATISTICAL ANALYSIS
  34. 34. • No patient loss follow up DEMOGRAPHICS: NO DIFFERENCE
  36. 36. Reasons for reintubation were not significantly different in the 2 groups
  37. 37. • In this RCT: PSV group results in: • Higher rate of successful extubation • The higher rate was related to more patients being extubated after the PSV-SBT • suggesting that a less demanding SBT better allows critically ill patients to demonstrated their ability to sustain breathing DISCUSSION
  38. 38. • A recent meta-analysis concluded that breathing through a T piece requires the same amount of work as breathing after extubation • the authors recommended that SBTs should be performed with T pieces because this approach better reflects the physiologic conditions after extubation • Physicians may be concerned that patients with low PSV and PEEP could develop RS failure after extubation DISCUSSION
  39. 39. • The current study found that the T-piece SBT was less well tolerated than the PSV SBT, although the work of breathing with the T piece may have been similar to breathing spontaneously • But reintubation rate was not significantly different in the 2 groups • No respiratory failure was observed after extubation from PSV • incidence of cardiac arrest was very low and higher in the T-piece group DISCUSSION
  40. 40. • Vallverdu et al: 64% of T-piece SBT failed SBT in first 30 minutes • Liang et al: identify characteristics of patients who failed SBT: • older • more cardiopulmonary disease • spent more time receiving mechanical ventilation before the SBT • undergone more previous SBTs • These patients may need longer SBT  what about 30 minutes? DISCUSSION
  41. 41. • In the present study: 30 minutes of PSV-SBT was enough to check patients’ ability to breathe without increasing the rates of post extubation respiratory failure and reintubation • Self-extubation during the SBT was more common in the T-piece group: tolerance of 30-min PSV is better than 30-min T-piece but latter group received longer MV DISCUSSION
  42. 42. • 2-hr T-piece and 2-hr PSV: • Matic et al: Higher rate of successful extubation in PSV group • Ezingeard et al: some patients can’t tolerate T-piece but PSV is okay without difference on reintubation rate • These result in T-piece is not the best way to check patients’ ability to breathe DISCUSSION
  43. 43. • In this study: • Reintubation rate: no difference • Logistic regression analysis showed that the 30-minute PSV SBT was associated with successful extubation • Extubation failure associated with longer MV and COPD • Hospital mortality and 90-day mortality: significantly higher in the T-piece group but cannot be explained by reintubation rate, days of MV after failed SBT, APACHE II, or hospital LOS DISCUSSION
  44. 44. • No protocol for prophylactic use of noninvasive ventilation and high-flow nasal cannula after extubation  no conclusion about the use of NIV and high flow nasal cannula for postextubation respiratory failure • Patients extubated outside of protocol could be expected to influence the main results, but the sensitivity analysis ruled out such bias • Investigators and attending physicians were not blinded LIMITATIONS
  45. 45. • Among mechanically ventilated patients, an SBT consisting of 30 minutes of PSV, compared with 2 hours of T-piece ventilation, led to significantly higher rates of successful extubation. • These findings support the use of a shorter, less demanding ventilation strategy for SBTs CONCLUSION
  47. 47. CRITICAL APPRAISAL • CASP checklist: 11 questions on • Are the results of the study valid? • What are the results? • Will the results help locally?
  48. 48. DID THE TRIAL ADDRESS A CLEARLY FOCUSED ISSUE? • Yes • PICO: • P: patients who have met weaning ventilator criteria • I: 30 min PSV-SBT • C: 2 hr T-piece-SBT • O: successful extubation
  49. 49. WAS THE ASSIGNMENT OF PATIENTS TO TREATMENTS RANDOMISED? • Yes, block of 4 • But investigators and attending physicians were not blinded
  53. 53. ASIDE FROM THE EXPERIMENTAL INTERVENTION, WERE THE GROUPS TREATED EQUALLY? • Can’t tell due to no protocol after extubation
  54. 54. HOW LARGE WAS THE TREATMENT EFFECT? • Appropriate outcomes measured • Clearly specified primary outcome • Large effect
  55. 55. HOW PRECISE WAS THE ESTIMATE OF THE TREATMENT EFFECT? • Besides no extubation strategy protocol, it was very precise
  56. 56. CAN THE RESULTS BE APPLIED TO THE LOCAL POPULATION, OR IN YOUR CONTEXT? • Yes • The participants affect general population
  59. 59. MY OPINION
  60. 60. MY OPINION • Very good • Borg dyspnea scale is subjective • Demographic: no neurosurgical patients • T-piece disadvantages • Require extra equipment • Require disconnection from the ventilator: no intrinsic monitor (ex: apnea monitoring) introduces risk and chance for medical error