Weaning protocols Extubation Weaning from prolonged mechanical ventilation Conclusion
Invasive mechanical ventilation is associated with risks and complications that prolong the duration of mechanical ventilation and increase the risk for death Increasing duration of mechanical ventilation itself is associated with increased mortality Epstein S. Complications in ventilator supported patients. In: Tobin M, editor.Principles and practice of mechanical ventilation, 2nd ed. New York:McGraw Hill; 2006. pp. 877 – 902. Esteban A, Anzueto A, Frutos F, et al. Characteristics and outcomes in adultpatients receiving mechanical ventilation: a 28-day international study. J AmMed Assoc 2002; 287:345–355
A multisociety consensus conference characterized the weaning process as a continuum lasting from intubation until hospital discharge Weaning from mechanical ventilation. EurRespir J 2007; 29:1033–1056. Recommendation of an international, multisociety consensus conference onweaning. Boles JM, Bion J, Connors A, et al.
A minority of patients fail and may need a more gradual approach, with success ultimately dependent on Identifying correctable causes for weaning intolerance. Once spontaneous breathing is tolerated attention shifts to determining whether the patient can be extubated
Recognizing that respiratory failure and respiratory muscle function have improved and the patient is capable of spontaneous breathing Patient tolerates first spontaneous breathing trial (SBT) and is successfully extubated (70% of all patients). Patient fails to tolerate initial SBT , successful weaning requiring up to three SBTs or up to 7 days from first SBT . Patient fails at least three SBTs or takes more than 7 days after the first SBT. Readiness Testing Simple weaning Difficult weaning Prolonged weaning
Approximately 1/3 of patients fall into the difficult and prolonged categories and experience higher ICU mortality (25%) than seen with simple weaning (5%).
The higher mortality
Complications of mechanical ventilation
Underlying illness leading to mechanical ventilation.
The patient’s capacity to breathe spontaneously is often underestimated . For example, 50% of patients who self-extubate do not require reintubation 30% of patients never satisfying objective readiness criteria can still be successfully weaned Patient-initiated device removal in intensive care units: a national prevalence study. Crit Care Med 2007; 35:2714–2720. Mion LC, Minnick AF, Leipzig R, et al. The prognostic significance of passing adaily screen of weaning parameters. Intensive Care Med 1999; 25: 581–587 Ely EW, Baker AM, Evans GW, et al.
A comprehensive evidence-based medicine review identified more than 50 objective physiologic tests (weaning predictors) as tools for assessing readiness for spontaneous breathing. Only five were associated with clinically significant changes in the probability of weaning success or failure but predictive capacity was modest
Epstein SK. Weaning parameters. Respir Care Clin N Am 2000; 6: 253–301.
MacIntyre NR, Cook DJ, Ely EW Jr, et al. Evidence-based guidelines for weaning and discontinuing ventilatory support: a collective task force facilitatedby the American College of Chest Physicians; the American Associationfor Respiratory Care; and the American College of Critical Care Medicine. Chest 2001; 120:375S–395S.
Meade M, Guyatt G, Cook D, et al. Predicting success in weaning from mechanical ventilation. Chest 2001; 120:400S–424S.
Negative inspiratory force (maximal inspiratory pressure).
(2) Minute ventilation.
(3) Respiratory frequency.
(4) Tidal volume.
(5) Frequency–tidal volume ratio ( f/VT).
Frequency–tidal volume ratio ( f/VT) How the measurements are made ? MEASUREMENTS AND RESULTS: Respiratory frequency (f) and tidal volume (VT) were measured during PS, CPAP, CPAP-R/A, and T-piece in all patients. RSBI (f/VT) was determined for each patient under all experimental conditions, and the average RSBI was compared during PS, CPAP, CPAP-R/A, and T-piece. RSBI was significantly smaller during PS (46+/-8 bpm/l), CPAP (63+/-13 bpm/l) and CPAP-R/A (67+/-14 bpm/l) vs. T-piece (100+/-23 bpm/l). Effect of pressure support ventilation and positive end expiratory pressure on the rapid shallow breathing index in intensive care unit patients. Intensive Care Med 2008; 34:505–510. El-Khatib MF, Zeineldine SM, Jamaleddine GW
Frequency–tidal volume ratio ( f/VT) The average sensitivity of 0.87 indicates that f/VT is a reliable screening test for successful weaning
Whether the f/VT, or any weaning predictor, actually facilitates weaning decision-making ? Interventions: Patients were screened daily for measures of oxygenation, cough and secretions, adequate mental status, and hemodynamic stability. Patients were randomized to two groups; in one group the f/Vt was measured but not used in the decision to wean (n = 151), but in the other group, f/Vt was measured and used , using a threshold of 105 breaths/min/L (n = 153). Patients passing the screen received a 2-hr spontaneous breathing trial. Patients passing the spontaneous breathing trial were eligible for an extubation attempt. A randomized, controlled trial of the role of weaning predictors in clinical decision making. Crit Care Med 2006; 34:2530–2535. Tanios MA, Nevins ML, Hendra KP, et al.
Whether the f/VT, or any weaning predictor, actually facilitates weaning decision-making ? Measurements and Main Results : Groups were similar with regard to gender, age, and Acute Physiology and Chronic Health Evaluation II score. The median duration for weaning time was significantly shorter in the group where the weaning predictor was not used (2.0 vs. 3.0 days, p = .04). There was no difference with regard to the extubation failure, in-hospital mortality rate, tracheostomy, or unplanned extubation . Conclusions: Including a weaning predictor f/Vt) in a protocol prolonged weaning time. In addition, the predictor did not confer survival benefit or reduce the incidence of extubation failure or tracheostomy. The results of this study indicate that f/Vt should not be used routinely in weaning decision making. A randomized, controlled trial of the role of weaning predictors in clinical decision making. Crit Care Med 2006; 34:2530–2535. Tanios MA, Nevins ML, Hendra KP, et al.
Am J Respir Crit Care Med 1999; 159:439–446. One explanation is the demonstrated safety of a closely monitored SBT.
Am J Respir Crit Care Med 2003; 167:120–127. In conclusion, in contrast to our hypothesis, weaning failure was not accompanied low-frequency fatigue of the diaphragm, although many weaning failure patients displayed diaphragmatic weakness.
Thus a failed SBT should not result in respiratory muscle injury as long as patients are quickly reconnected to the ventilator when signs of weaning intolerance occur.
Although unproven, structural respiratory muscle injury may occur if the failed weaning trial is improperly extended.
These concepts are supported by the ABC trial in which greater than 50% passed an SBT when readiness was assessed using liberal oxygenation criteria (SpO2 88% on FiO2 0.5 and PEEP 8cmH2O) and weaning predictors were not used Efficacy and safety of a paired sedation and ventilator weaning protocol for mechanically ventilated patients in intensive care (awakening and breathing controlled trial): a randomised controlled trial. Lancet 2008; 371:126–134. Girard TD, Kress JP, Fuchs BD, et al.
Direct extubation after satisfying readiness criteria alone is unwise, as 40% of such patients require reintubation Therefore a trial of spontaneous breathing, carried out on low-level pressure support (PSV7mmHg), CPAP, or unassisted through a T-piece , is indicated. Randomized controlled trials indicate these techniques are equivalent Weaning from mechanical ventilation: a model for extubation. Intensive Care Med 1999; 25:1077–1083. Zeggwagh AA, Abouqal R, Madani N, et al.
Theoretically, PSV more effectively counterbalances endotracheal tube-related resistive workload , but a given level may either overcompensate or under-compensate for imposed work
Automatic tube compensation (ATC) SBTs conducted with either ATC, PSV, or T-piece to be equivalent Extubation after breathing trials with automatic tube compensation, T-tube, or pressure support ventilation. Acta Anaesthesiol Scand 2002; 46:973–979. Haberthur C, Mols G, Elsasser S, et al.
Automatic tube compensation (ATC) Higher SBT success for ATC compared to CPAP Extubation outcome following a spontaneous breathing trial with automatic tube compensation versus continuous positive airway pressure. Crit Care Med 2006; 34:682–686. Cohen JD, Shapiro M, Grozovski E, et al.
Automatic tube compensation (ATC) Patients failing a 30- min T-tube trial , immediate conversion to PSV 7cmH2O for additional 30 min led to weaning success in 21 of 31 patients, suggesting the endotracheal tube can contribute to iatrogenic weaning failure Weaning from mechanical ventilation with pressure support in patients failing a T-tube trial of spontaneous breathing. Intensive Care Med 2006; 32:165–169 Ezingeard E, Diconne E, Guyomarc’h S, et al.
In two studies suggesting that 30 min is equivalent to 120 min with either T-piece or PSV Optimal SBT duration may depend upon the duration of ventilation or the underlying cause for respiratory failure. Optimal SBT duration
75 patients with chronic obstructive pulmonary disease (COPD), ventilated for 15 or more days, found a median time to trial failure of 120 min Therefore, in some patients the SBT should be extended to at least 120 min. Optimal SBT duration Comparison of two methods for weaning patients with chronic obstructive pulmonary disease requiring mechanical ventilation for more than 15 days. Am J Respir Crit Care Med 2001; 164:225–230. Vitacca M, Vianello A, Colombo D, et al.
Imbalance between respiratory load and capacity (e.g. diaphragmatic strength and endurance)
Excessive load may be imposed by the
Heat and moisture exchange devices,
Ventilator tubing and valves
Intrinsic factors such as
Increased airways resistance,
Increased elastance from dynamic hyperinflation,
Reduced respiratory muscle capacity are more
An important component of load/capacity imbalance is reduced respiratory muscle strength .
Cardiac dysfunction contributes to weaning failure especially in patients with coronary artery disease or chronic heart failure
Myocardial ischemia ( release in catecholamines )
Pulmonary edema ( elevation of transmural
pulmonaryartery occlusion pressure)
Patients at risk for weaning failure from cardiac disease can manifest an elevated B-type natriuretic peptide (BNP) or N-terminal pro-BNP In one study, a pre-SBT BNP >275 pg/dl correlated with a longer duration of weaning
The stress of weaning is considerable as it results in
increased levels of plasma insulin , cortisol , and glucose .
Lastly, positive fluid balance has been associated with
The effects of different weaning modes on the endocrine stress response. Crit Care 2004; 8:R31–R34. Koksal GM, Sayilgan C, Sen O, et al. Fluid balance and weaning outcomes. Intensive Care Med 2005; 31:1643–1647. Upadya A, Tilluckdharry L, Muralidharan V, et al.
How long should the patient rest after a failed weaning effort? When clinical evidence of respiratory muscle fatigue is absent, multiple daily SBTs are well tolerated. Yet, a comparison of two international studies found declining use of this approach from 1998 to 2004 If unequivocal evidence for fatigue is evident then clinicians should consider providing 24 h of rest on full support before preceding with the next weaning effort Pattern of recovery from diaphragmatic fatigue over 24 h. J Appl Physiol 1995; 79:539–546. Laghi F, D’Alfonso N, Tobin MJ.
The clinician must decide whether to perform daily SBTs or whether to more gradually reduce ventilatory support (progressive withdrawal). A randomized trial showed no benefit to using inspiratory muscle training Inspiratory muscle training is ineffective in mechanically ventilated critically ill patients. Clinics 2005; 60:479–484 Caruso P, Denari SD, Ruiz SA, et al.
Two RCTs compared progressive withdrawal techniques in patients satisfying readiness criteria but intolerant of a 2-h SBT Although one study found T-piece superior and the other observed PSV to be most efficient, both demonstrated that synchronized intermittent mandatory ventilation (SIMV) alone delays the process.
A more recent investigation randomized patients to SBTs (120 min) with T-piece or PSV and found the latter associated with decreased weaning time, duration of mechanical ventilation, and ICU length of stay Comparison of pressure support and T-tube weaning from mechanical ventilation: randomized prospective study. Croat Med J 2004; 45:162–166 Matic I, Majeric-Kogler V
Noninvasive ventilation (NIV) Three published RCTs have explored the use of noninvasive ventilation (NIV) in patients having trouble weaning from mechanical ventilation Studies indicate that NIV can facilitate weaning in a highly select group of patients with acute on chronic lung disease
SBT readiness criteria must be satisfied
Extubation criteria must be satisfied
The patient must be a good candidate for NIV (able to breathe spontaneously
for at least 5–10 min and not be a difficult reintubation).
Can the weaning process be automated? One multicenter study randomized 144 patients to Conventional weaning VS Computerized weaning using a closed loop knowledge- based system A multicenter randomized trial of computer-driven protocolized weaning from mechanical ventilation. Am J Respir Crit Care Med 2006; 174:894–900. Lellouche F, Mancebo J, Jolliet P, et al.
The computer-driven ventilator continuously monitors physiologic parameters
Adjusts pressure support by 2–4cmH2O to maintain the patient in a ‘zone of comfort’. When a minimal level of PSV is reached, a SBT is conducted and the clinician prompted if the SBT proves successful . Computer-driven ventilation resulted in decreased duration of weaning, total duration of ventilation, median ICU stay, without adverse event or increase in reintubation.
In certain settings, uncontrolled investigations and RCTs demonstrate improved outcome with protocol-driven weaning implemented by physicians or by respiratory care practitioners and ICU nurses Standard care VS Intervention strategy patients passing the daily screen underwent a 2-h SBT with a prompt for extubation if the trial was tolerated
Observational and randomized trials demonstrate that protocols directed at minimizing the use of sedative infusions shorten the weaning process . Specifically, approaches intended to avoid over sedation by limiting the use of continuous infusions either through sedation assessment scoring or by daily cessation of Sedative infusions decrease duration of mechanical ventilation and duration of ICU stay.
Between 25 and 40% of patients develop signs of respiratory distress after extubation Extubation failure, when defined as reintubation within the subsequent 24–72 h , occurs in 5–20% of patients , depending on the patient population
Risk is greatest for medical and neurologic patients.
ICU and hospital stays, greater need for tracheostomy, and more
frequently require long-term acute care
Decision to extubate. Intensive Care Med 2002; 28:535–546 . Epstein SK.
Avoidable delays in extubation prolong ICU stay, heighten the risk for pneumonia, and increase hospital mortality Measuring blood gases at the end of the SBT ? Implications of extubation delay in brain-injured patients meeting standard weaning criteria. Am J Respir Crit Care Med 2000; 161:1530–1536. Coplin WM, Pierson DJ, Cooley KD, et al.
Are blood gases necessary in mechanically ventilated patients who have successfully completed a spontaneous breathing trial?
Respir Care 2004; 49:1316–1319.
Pawson SR, DePriest JL.
The effect of arterial blood gas values on extubation decisions.
Respir Care 2003; 48:1033–1037.
Salam A, Smina M, Gada P, et al.
In general, traditional weaning predictors perform poorly in predicting extubation outcome Risk factors for extubation failure in patients following a successful spontaneous breathing trial. Chest 2006; 130:1664–1671. Frutos-Vivar F, Ferguson ND, Esteban A, et al.
One promising technique has demonstrated that risk of extubation failure is associated with greater time needed to return to baseline minute ventilation after resumption of full ventilatory support Serial measurements of f/VT can predict extubation failure in patients with f/VT < or 105? J Crit Care 2008; 23:572–576. Teixeira C, Zimermann Teixera PJ, Hohe¨ r JA, et al.
Measuring the airway occlusion pressure at 0.1 s (P0.1) and the degree of expiratory flow limitation Respiratory failure in chronic obstructive pulmonary disease after extubation: value of expiratory flow limitation and airway occlusion pressure after one 0.1 second (P0.1). J Crit Care 2008; 23:577–584. Vargas F, Boyer A, Bui HN, et al.
Extubation failure often results from inability to protect the airway and manage respiratory secretions Recent RCTs demonstrate that systemic corticosteroids can reduce postextubation stridor, especially in high-risk patients Intravenous injection of methylprednisolone reduces the incidence of postextubation stridor in intensive care unit patients. Crit Care Med 2006; 34:1345–1350. Cheng KC, Hou CC, Huang HC, et al.
For example, Cheng et al. Randomized 128 high-risk patients ( cuff leak volume <24% of tidal volume ) to placebo or methylprednisolone injection (multi-dose or single-dose) during the 24 h prior to extubation . Treatment with methylprednisolone significantly reduced the risk for postextubation stridor and need for reintubation Intravenous injection of methylprednisolone reduces the incidence of postextubation stridor in intensive care unit patients. Crit Care Med 2006; 34:1345–1350. Cheng KC, Hou CC, Huang HC, et al.
The ability to protect the airway is also dependent upon cough strength and volume of respiratory secretions (e.g. suction requirement > every 2 h) Mental status is also important, although studies looking exclusively at this parameter have come to conflicting conclusions
Peak cough flow rates (cut-off <60 l/min),
Secretions (cut-off >2.5 ml/h),
Abnormal mental status (inability to complete four simple
Highly predictive of extubation outcome.
Failing all three criteria led to certain extubation failure, whereas the absence of all three was associated with only a 3% risk for reintubation
Neurologic status, cough, secretions and extubation outcomes. Intensive Care Med 2004; 30:1334–1339. Salam A, Tilluckdharry L, Amoateng-Adjepong Y, et al.
10% ~ 20% of patients with acute respiratory failure require 21 or more days of ventilatory support and thus constitute a subset of prolonged mechanical ventilation defined earlier A recent multicenter observational study of more than 1400 patients transferred to long-term care hospitals found that 50% could be successfully weaned from mechanical ventilation
Weaning efforts should start as soon as possible after transfer as 10–30% of patients with prolonged mechanical ventilation will tolerate their initial SBT and be liberated The only RCT in prolonged mechanical ventilation found no difference between PSV weaning and tracheotomy collar trials of increasing duration in 52 COPD patients
Determining readiness is best achieved using liberal oxygenation criteria