The weaning parameters the McMaster report 8 showed us, I think, are good guidelines, but they're just guidelines. I get concerned if we make them absolute thresholds that state: below this you can go, and above this you cannot go.
Me too, partly because often we're dealing with patients who have poor respiratory-system compliance. They start from a rapid-shallow-breathing index [breathing frequency divided by tidal volume] of 80 with pressure support, when they're perfectly comfortable. As they exercise during the SBT, they may comfortably go to I've extubated patients with rapid-shallow-breathing indexes greater than !
The Tanios 9 study clearly showed that using that number as an absolute threshold produced longer stay on the ventilator. What do you think our target should be for the extubation failure rate, to say we're doing a good job? Extubation failure rate is a nice monitoring tool for how your unit is performing.
Should the reintubation rate be zero? Well, if it's zero, chances are you're waiting too long and missing a good number of patients. Well, that seems pretty high, if it's just a flip of a coin. I think that's probably a reasonable rate.
I'm not so sure. I was pretty sure, but now looking through the recent literature on problems with reintubation, the mortality associated with reintubation, and so forth. Maybe they had that before, but I think we have to be careful to say that an SBT means extubation automatically. Why can't we let them sit for a day until they're ready to be extubated? They're two entirely different assessments: one is whether they need the ventilator, and the other is whether they need the tube.
All too often those two assessments get lumped together. Exactly: I agree. This is one of our biggest problems and challenges. To really be ready to extubate, maybe my anesthesiology colleagues are better than I am, because we're still struggling.
The thing that always concerns me about those numbers is that they're lumped together based on RCTs that were primarily done in medical patients. There's some surgical patients in there, but every one of the studies had a large number of medical patients.
I expect them to be higher in a medical unit than in a surgical unit. It has to be for your unit and your trends over time. Obviously, we all should be working toward the lowest reasonable reintubation rate and looking at the duration of mechanical ventilation. This is one of our quality measures back home. No, our general surgical. We have not measured this in the cardiothoracic unit. I agree with you that in the cardiothoracic unit it's probably much lower.
My point is that I think you've got to do it unit by unit. Not use an institutional number. Because, like Neil, we think that we know what we're doing and that we can manage patients appropriately without SmartCare. But, like Neil, we are not your typical community hospital. We should distinguish the need for airway protection from the need for positive pressure, which can be applied noninvasively. If the patient can cough, he or she can be extubated to NIV.
If the patient can't cough, or fails extubation to NIV, then tracheostomy may be the best option. I want to follow up something John said, that I think touches on the issue of clinician automatic pilot. You do an SBT; the patient fails after only a couple minutes; you put them back on full support. If you suddenly withdraw ventilatory support and the workload is abruptly transferred to the patient, it tends to freak some of them out, which is one reason I don't necessarily like the idea of pairing the SBT with the sedation interruption.
If a patient does freak out on SBT, just put them on a pressure support level where they're comfortable and see over 5 or 10 minutes if you can gradually titrate the pressure support back down to where it's an SBT. If they can't adapt after about 10 minutes, I think you have your answer. But I also think that when we put a protocol like SBT into operation, we don't anticipate some important practical ramifications.
So the recent iteration of the SBT protocol at our hospital allows up to 30 minutes to get the patient accommodated. One nice thing about the approach I described is that you can dial the pressure down: you don't have to go from 15 to 5. You can go from 15 to 12 to 10 in a few minutes, while you're standing there.
And, John, just to clarify a point that you made, when I say that in between SBTs we keep them comfortable, it is still with a ventilator work load. Instead, the diaphragm is very much like the heart, which also is not designed to be totally rested.
You don't treat heart failure with asystole: at least not for very long. I'm sure you and I agree that keeping the patient comfortable with a reasonable level of activity is important in between the SBTs. I think a lot of areas of intensive care are going toward less aggressively supported care and more towards trying to adapt patients to their diseases.
And part of that adaptation is episodic stress. In recreational exercise we stress ourselves much more than when at rest, and we build endurance, strength, and muscle. If we keep these people fully supported and doing only gentle amounts of work, and then ask them to do the equivalent of athletic exercise during the SBT, we may be setting them up for failure.
The old idea of periodically doing sprints SBTs may hold water. If you do them several times each day, leading up to the final evaluation for extubation, perhaps such conditioning and training might re-educate the neural drive and improve muscular efforts.
Just a thought. That's a good thought, and I've often wondered if we could exercise and train the muscle recovering from a respiratory failure.
At some points I've thought maybe we could, but I haven't see much evidence to suggest that it's possible. I'm still not sure if it's possible to train or exercise a muscle that's been beaten and battered by the systemic inflammatory response syndrome and all the metabolic derangements that go along with it. But I'm keeping an open mind. NOTE: We only request your email address so that the person you are recommending the page to knows that you wanted them to see it, and that it is not junk mail.
We do not capture any email address. Skip to main content. Research Article Conference Proceedings. Neil R MacIntyre. Abstract The ventilator discontinuation process is an essential component of overall ventilator management.
Introduction Patients require positive pressure mechanical ventilator support through an artificial airway for many reasons. Scope of the Problem A large observational study from Europe involved 4, mechanically ventilated patients from ICUs in View this table: View inline View popup Download powerpoint. Assessing the Need for an Artificial Airway Once a patient has been deemed to no longer need mechanical ventilatory support or perhaps is deemed a candidate for noninvasive ventilation , 42 , 54 attention then turns to the assessment of the need for the artificial airway.
The Role of Tracheostomies A tracheostomy offers several putative advantages over a translaryngeal airway. Summary The ventilator discontinuation process is an essential component of overall ventilator management. E-mail: neil.
Dr MacIntyre has disclosed a relationship with CareFusion. References 1. Evidence-based guidelines for weaning and discontinuing ventilator support: a collective task force facilitated by the American College of Chest Physicians, the American Association for Respiratory Care, and the American College of Critical Care Medicine. Chest ; 6 : S - S. Also in: Respir Care ;47 1 Effect on the duration of mechanical ventilation of identifying patients capable of breathing spontaneously.
N Engl J Med ; 25 : - Nosocomial pneumonia in ventilated patients: a cohort study evaluating attributable mortality and hospital stay. Implications of extubation delay in brain injured patients meeting standard weaning criteria , Am J Respir Crit Care Med ; l61 5 : - Konno-Mead analysis of rib cage-abdominal motion during successful and unsuccessful trials of weaning from mechanical ventilation.
Am Rev Respir Dis ; 6 : - OpenUrl PubMed. Jubran A , Tobin MJ , Pathophysiological basis of acute respiratory distress in patients who fail a trial of weaning from mechanical ventilation. Outcome of reintubated patients after scheduled extubation. J Crit Care ; 26 5 : - Effect of failed extubation on the outcome of mechanical ventilation. Chest ; 1 : - Clinical characteristics, respiratory functional parameters, and outcome of a two-hour T-piece trial in patients weaning from mechanical ventilation.
The prognostic significance of passing a daily screen of breathing spontaneously. Int Care Med ; 25 6 : - Independent effects of etiology of failure and time to reintubation on outcome for patients failing extubation. A comparison of four methods of weaning patients from mechanical ventilation: the Spanish Lung Failure Collaborative Group.
N Engl J Med ; 6 : - Comparison of three methods of gradual withdrawal from ventilatory support during weaning from mechanical ventilation. Evaluation of a knowledge-based system providing ventilatory management and decision for extubation. Ventilator discontinuation: why are we still weaning? MacIntyre NR. Respiratory factors in weaning from mechanical ventilatory support. Respir Care ; 40 3 : - Ventilator-induced lung injury: from the bench to the bedside. Inten Care Med ; 32 1 : 24 - Patient-ventilator interactions: optimizing conventional ventilation modes.
Respir Care ; 56 1 : 73 - Using protocols to improve the outcomes of mechanically ventilated patients. Focus on weaning and sedation. Crit Care Clin ; 17 4 : - Mechanical Ventilation International Study Group. Characteristics and outcomes in adult patients receiving mechanical ventilation: 1 day international study. JAMA ; 3 : - Weaning from mechanical ventilation.
Eur Respir J ; 29 5 : - Characteristics and outcomes of ventilated patients according to time to liberation from mechanical ventilation. Management of patients requiring prolonged mechanical ventilation. Chest ; 6 : - Chronic critical illness: the growing challenge to health care. Respir Care ; 57 6 : - White AC. Long term mechanical ventilation: management strategies. Yang KL. Reproducibility of weaning parameters: a need for standardization.
Evidence report on criteria for weaning from mechanical ventilation. Contract No. Clinical diagnoses and autopsy findings: discrepancies in critically ill patients. Crit Care Med ; 40 3 : - A randomized, controlled trial of protocol-directed versus physician-directed weaning from mechanical ventilation.
Crit Care Med ; 25 4 : - Effect of spontaneous breathing trial duration on outcome of attempts to discontinue mechanical ventilation: the Spanish Lung Failure Collaborative Group. Breathing measurements reduces false negative classification of atachypneic pre-extubation trial failures. Crit Care Med ; 24 6 : - A randomized controlled trial of the role of weaning predictors in clinical decision making. Crit Care Med ; 34 10 : - A prospective study of indexes predicting the outcome of trials of weaning from mechanical ventilation.
N Engl J Med ; 21 : - Clinical manifestations of inspiratory muscle fatigue. Neuroventilatory efficiency and extubation readiness in critically ill patients. Crit Care ; 16 4 : R Positive end-expiratory pressure vs T-piece: extubation after mechanical ventilation Chest ; 6 : - The role of continuous positive airway pressure during weaning from mechanical ventilation in cardiac surgical patients. Anaesthesia ; 50 8 : - Continuous positive airway pressure reduces work of breathing and dyspnea during weaning from mechanical ventilation in severe chronic obstructive pulmonary disease.
Am Rev Respir Dis ; 2 : - Tobin MJ. Jubran A , Tobin MJ. Passive mechanics of lung and chest wall in patients who failed or succeeded in trials of weaning. Role of the respiratory muscles in acute respiratory failure of COPD: lessons from weaning failure. The patients indicated the level of perceived exertion by mouthing the number, circling it on a visual analog scale, writing it, or holding up their fingers. The IST was attempted once a day, 6 to 7 times a week.
Four sets of 6 to 8 breaths were completed every training day, with a 5- to minute rest between sets. When resting, patients were placed on the ventilator if they were not undergoing UBTs.
If they were undergoing UBTs, they rested using a tracheostomy tent with humidified or nonhumidified oxygen. Some treatments had to be deferred until the patient's medical status stabilized. The appropriateness of these training pressure levels was measured after every set by administration of the perceived exertion scale. Figure 3 shows training pressures over time.
Treatments lasted from 30 to 50 minutes including rest between sets , depending on the patients' ability to tolerate treatment that day and any complications eg, unwillingness or inability [severe dyspnea] to perform back-to-back sets; increased heart rate, blood pressure, or respiratory rate; technical difficulties with the cuff; overmedication; nausea; vomiting. As with the MIP measurement, patients were treated with the head of the bed elevated to 45 degrees or more and were encouraged to breathe deeply and slowly.
Each patient's heart rate and blood pressure were kept within the norms specified by the physician. These norms varied from patient to patient, and no log of each specific norm was kept. Treatment was discontinued or delayed until values returned to acceptable levels, as determined by each patient's physician. To promote consistency of treatment and patient cooperation, the UBTs were usually initiated at the same time each day, typically in the morning, when the patients were likely to be most awake and alert.
Because adequate sleep is essential for effective participation, 5 , 8 ICU team members were encouraged to conduct tests and procedures during daytime hours. When IST was initiated, all patients began concurrent general rehabilitation including active and active-assisted range of motion exercises, low-level resistive limb exercises or passive range of motion exercises, and stretches to all extremities administered by the first author.
Three of the 6 patients patients 3, 4, and 5 tolerated transfer training, standing and sitting balance, and marching in place, which was done after the IST session. When they tolerated UBTs between 0. These were targeted progressions, and not all trials could increase in this manner. The ICU team physicians, nurses, respiratory therapists evaluated each patient's condition throughout all UBTs and interpreted the patient's comfort level and vital signs, halting the UBTs if the patient's vital signs were outside of the norms or the patient perceived inability or discomfort with continuation of the UBTs.
The physicians decided when the patients would return to the ventilator. The physicians also determined the specific ventilator settings, which generally consisted of decremental synchronized intermittent mandatory ventilation or pressure support. An explanation of the specific implementation and titration of the various ventilator settings used with these patients is beyond the scope of this report. Because the diaphragm almost exclusively takes over the work of breathing during sleep, it is more susceptible to fatigue at that time, and increased ventilatory support is important.
Many investigators 5 , 8 , 10 , 20 have emphasized the need for adequate rest during attempts to wean from the ventilator. Patients were considered weaned after they were off the ventilator for 48 hours. Treatment was discontinued after the patients had been transferred to the hospital's general medicine ward, usually within 3 to 5 days after last being on the ventilator. All patients were weaned from the ventilator in 9 to 28 days mean of 17 days after the initiation of IST, and none required additional MV once weaned except for patient 6, who died of renal failure 4 days after being returned to MV and after being off the ventilator for 21 days Fig.
Mean training pressures increased from 9. The MIP increased from a mean of All patients were discharged from the ICU to the general medical ward, where patient 1 died from a mucus plug occlusion while being repositioned 20 days after weaning from the ventilator. The remaining patients were then transferred to a rehabilitation unit and discharged to home or to a nursing home.
The first mechanism is reversal of disuse atrophy affecting the muscles of respiration. Many commonly used settings of the ventilator appear to take over much of the work of breathing, and among the current literature there is a question as to the extent of disuse atrophy or the evidence of any significant disuse atrophy.
In our patients and patients reported in previous research, 8 , 10 the total time that the patients were on MV correlated with difficulty in weaning. Studies of rats and primates with phrenic nerve disruption on controlled MV have shown significant inspiratory muscle strength decrease and deterioration in the contractile properties of the diaphragmatic muscle tissue.
This finding suggests what the literature 5 , 8 , 10 supports, that length of time on the ventilator is not directly correlated with respiratory muscle atrophy.
The level of muscle atrophy, if any, cannot be accurately inferred in patients who are dependent on a ventilator, regardless of the length of time on MV. A second explanation for the possible contribution of IST in weaning these patients from MV is that the training altered neuromuscular dysfunction specific to inspiration. The authors of that report believed that these diseases were the most important factor related to prolonged ventilator dependency in all patients with CVD.
They further concluded that the diseases probably resulted from the patients' prolonged critical illness and subsequent or concurrent MV dependence. Other studies 36 — 38 have also shown the prevalence of polyneuropathies among patients in ICUs that contribute to ventilator dependency, and some studies 26 — 28 showed that MV inhibits normal functions of the central and peripheral neuromuscular components in the respiratory systems of people without known neuromuscular disease who were on MV for short periods.
Milner-Brown and Miller 39 demonstrated that patients with diverse neuromuscular diseases can increase their limb strength through a high-load, low-repetition strengthening program similar to the one used described in our report. The rapid strength gains demonstrated by the patients in our report indicate a neural adaptation response to the training. A third possible explanation of these patients' progress involves improvement in their breathing patterns ie, slow, deep breathing versus rapid, shallow breathing that may have resulted from IST.
As Caruso et al 33 observed, when patients breathe against a resistance that they cannot overcome, they increase their effort in an attempt to breathe to fulfill their physiological requirements. All patients were encouraged by the first author to sustain the required force production for the duration of their inspiration, which led to a standardized training breath. Capdevila et al 9 found that patients' breathing patterns reveal an increase in both mean inspiratory force and duration of inspiration as they are weaned from MV.
Future studies of IST in the weaning of patients with CVD should show whether the standardization of training breaths translates to deeper, slower, and more effective breathing during UBTs that promotes weaning. Tobin and Alex 8 noted that much variation exists in techniques for determining when a patient is ready for weaning and how progressive decreases in positive pressure and time off the ventilator are carried out.
We believe that the attempted systematization of the UBT after IST was initiated in our 6 patients may have accelerated weaning. Study of patients who are ventilator-dependent is needed to identify the point at which IST should begin relative to UBT as well as the frequency and duration by which UBTs are increased. Effects related to interpersonal factors between the therapist and the patient and to participation in a general rehabilitation program cannot be ruled out because IST requires close, almost daily, interaction between the therapist and the patient.
All but a few of the interventions described in this report were carried out by the first author, who also provided general rehabilitation for the 6 patients.
Any attempt to further study the effectiveness of IST in the weaning of patients with CVD from the ventilator should take into account the possible effects of a general rehabilitation program and the psychosocial component of the patient-therapist relationship.
It is important to note that 2 patients who were weaned from MV subsequently died from other medical problems. Weaning from a ventilator allowed them to interact with their loved ones in the interim, and all of the patients stated that their quality of life increased after weaning. This suggests that even patients who are chronically or terminally ill might benefit from IST.
Three of the patients patients 1, 2, and 6 had been diagnosed with chronic renal insufficiency or renal failure and were undergoing hemodyalisis during IST. Patients 1 and 6 had been discharged from the hospital to stand-alone ventilator weaning facilities for and 50 days, respectively, prior to the IST trials, but they were unsuccessful in attempts at weaning at those hospitals.
They were subsequently weaned after 28 days of IST. All the patients in this report had compromised nutritional status, and all were colonized or septic with virulent strains of microbes. Poor nutritional status, sepsis, renal failure, and long-term dependence on MV are often cited as major threats to weaning from MV.
Initiating a program of IST intervention in any hospital may be difficult because the patients are often have complex medical problems and the intervention is new. The ICU team physicians, nurses, respiratory therapists need to coordinate their efforts to enable the regular, consistent, and progressive muscle training protocol. The discontinuation or tapering of corticosteroids, neurodepressants, and muscle relaxants, if possible, is important, because they can make weaning more difficult.
Therapists who want to use IST for weaning patients from ventilators need to be prepared for difficulties. Patients with CVD are often critically ill and may be anxious and apprehensive about attempts to discontinue MV. As noted in Liaw and colleagues' 19 report of a study on resistive IMT in patients with acute, complete cervical spinal cord injury, only highly motivated patients are able to complete the treatments necessary to breathe off the ventilator for strength gains, and they must be closely supervised and constantly encouraged.
Especially during the first few UBTs, therapist must be present to decrease patients' anxiety and ensure their comfort. In conclusion, this case report illustrates how the use of IST with patients who are ventilator-dependent may promote weaning, even in people who are terminally ill. Although our case report could not demonstrate a cause-and-effect relationship between IST and weaning, it did reveal questions for future research: 1 Did IST facilitate the weaning of these patients, and if so, how?
Until these questions are answered by controlled studies, we believe that physical therapists can use IST in acute care and long-term ventilator rehabilitation hospitals if it is applied in a careful and team-oriented manner. Both authors provided writing and data analysis. Mr Hopkins provided consultation including review of manuscript before submission. Wagner DP. Economics of prolonged mechanical ventilation.
Am Rev Respir Dis. Google Scholar. Approach to patients with long-term weaning failure. Respir Care Clin North Am. Long-term outcomes for elderly survivors of prolonged ventilator assistance. Cost containment and mechanical ventilation in the United States. New Horizons. Weaning from mechanical ventilation. Crit Care Clin. Engoren M. Marginal cost of liberating ventilator-dependent patients after cardiac surgery in a stepdown unit. Ann Thorac Surg. Civetta JM. Nosocomial respiratory failure or iatrogenic ventilator dependency.
After evaluation for reversible causes of weaning failure, it is recommended that a protocolized approach to weaning be used. There are several elements to a weaning protocol screening, SBTs, and progressive withdrawal :. At least once per day the patient should be screened for readiness for weaning. Screening should be deferred if the patient has active myocardial ischemia, has a newly developing significant medical problem e.
The following screening criteria should be used:. No or only low doses of vasoactive agents should be necessary to maintain an adequate blood pressure. Patients passing the readiness screen should undergo either an SBT or progressive withdrawal of ventilatory support. Multiple daily SBTs are acceptable as long as there is no clinical evidence for respiratory muscle fatigue.
Patients tolerating a SBT should be considered for extubation see below. Many experts will combine SBTs with progressive withdrawal. With this strategy, the patient passing the SBT is considered for extubation. The patient failing the SBT is returned to mechanical ventilation, where efforts at progressive withdrawal continue.
Extubation success is greatest when all three are present and risk for extubation failure is greatest when all three are absent. Patients with poor mental status but minimal secretions and adequate cough can often be successfully extubated. In addition, patients should not have evidence of upper airway obstruction. Those deemed to be at increased risk for upper airway obstruction prolonged intubation, traumatic intubation, multiple intubations, large endotracheal tube for native airway size should undergo a cuff leak test to assess patency of the upper airway.
Patients not passing the readiness screen or intolerant of either SBTs or decreases in ventilatory support should continue to undergo investigation to identify reversible causes of weaning failure. In select patients intubated with COPD exacerbation, and acute-on-chronic respiratory failure, consideration may be given to using non-invasive ventilation NIV as a weaning technique. The patient should have satisfied the screening criteria for readiness and the criteria for extubation.
The patient must be able to tolerate spontaneous breathing for at least minutes to allow for NIV interface and ventilator adjustments. Once placed on NIV the patient demonstrates unequivocal improvement within hours decreased dyspnea, decreased respiratory rate, decreased use of accessory respiratory muscles and improving ventilation as assessed by arterial blood gases.
Protocols to reduce sedation shorten the duration of mechanical ventilation. These strategies seek to avoid continuous intravenous sedation, which has been associated with worse outcomes. Sedation may be reduced by daily cessation — all sedation stopped until the patient awakens or becomes agitated.
A strategy combining daily cessation spontaneous awakening trials with daily SBTs improves outcome. An alternative approach is a sedation algorithm designed to reduce sedation to the level needed to keep the patient in an alert, calm and cooperative state e. Protocols designed to avoid hyperglycemia improve outcomes accelerates weaning and shortens the duration of mechanical ventilation.
There is increasing evidence that early physical and occupational therapy is safe and associated with improved outcomes. This approach must be combined with one designed to reduce the level of sedation to allow for a patient capable of participating in rehabilitation activities. To date there is no convincing evidence that early tracheostomy performed on days improves outcome when compared to that performed later after days.
Thus early tracheostomy may subject the patient to an unnecessary procedure. Nevertheless, for some patients with difficulty weaning tracheostomy may facilitate liberating the patient from mechanical ventilation. These benefits may directly address the pathophysiologic cause of weaning failure in a given patient. If such a factor cannot otherwise be rapidly corrected or the patient is anticipated to require another more than another days of mechanical ventilation then the patient should be considered for tracheostomy.
This role is best demonstrated in RCTs of weaning protocols and of those used to minimize sedation. Consensus conference recommendations. Eur Respir J. Intensive Care Med. Observational study showing positive fluid balance in the 24, 48, and 72 h prior to weaning was significantly greater in weaning failure when compared to weaning success. One of several studies indicating that failure to increase cardiac output during weaning is associated with weaning failure.
Crit Care Med. Observational study showing that critical illness neuromyopathy is associated with prolonged weaning and delayed extubation. Patients failing weaning trials did not demonstrate evidence for respiratory muscle fatigue. The change from positive-pressure mechanical ventilation to T-piece, negative intrathoracic pressure, resulted in a dramatic increase in the transmural pulmonary artery occlusion pressure.
The plasma B-type natriuretic peptide, BNP, level measured prior to weaning was higher in patients with subsequent weaning failure. Serial measurements of N-terminal pro-brain natriuretic peptide plasma levels identified COPD patients with weaning failure secondary to acute cardiac dysfunction. Jubran, A, Tobin, MJ. Observational study of COPD patients showing those failing to wean develop worsening respiratory mechanics, including increases in the resistive and elastic work of breathing.
Observational study of heterogenous patients showing that weaning failure is associated with an imbalance between respiratory muscle capacity and load on the system. Epstein, SK. Curr Opin Crit Care.. Detailed review of weaning process. N Engl J Med.
Randomized controlled trial showing that compared to usual care, a weaning protocal combining daily screening and spontaneous breathing trials shortens the duration of weaning. Randomized controlled trial showing that progressive withdrawal consisting of systematic reduction in the level of PSV was superior to T-piece and IMV weaning.
Randomized controlled trial demonstrating that use of the frequency-tidal volume ratio as part of a daily screen slowed the process of weaning and did not shorten the duration of mechanical ventilation. Systematic review of parameters used to determine readiness for weaning. Randomized controlled trials showing that a sedation algorithm, targeted to a sedation scoring system, shortens the duration of mechanical ventilation. Randomized controlled trial showing that daily cessation of sedation shortens the duration of mechanical ventilation.
Subsequent analyses from the same group demonstrated that this approach did not precipitate myocardial ischemia and reduced the number of neurodiagnostic procedures needed.
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