Increased respiratory drive, resulting from physiologic hypoxemia, increased CO2 production, metaboic acidosis, increased dead space or non-physiologic anxiety , can lead to difficult weaning, especially in the patient with expiratory airflow obstruction asthma or COPD. In this setting, increased minute ventilation can worsen dynamic hyperinflation. Decreased ventilatory drive usually impedes the weaning process by delaying the initiation of weaning, though on occasion it can manifest as intolerance to weaning e.
Recognition of this relationship has led clinicians to utilize strategies to decrease sedation. This can be achieved by using a sedation algorithm that targets a patient who is awake, alert or easily arousable , and cooperative. Alternatively, the same goal can be achieved by daily interruption of sedation. This cardiac limitation to weaning is a result of a complex cardiopulmonary interaction.
Therefore, in the presence of significant cardiac dysfunction, there may be inadequate blood flow and oxygen delivery to the respiratory muscles, predisposing to their fatigue and failure. Indeed, patients who wean successfully will increase cardiac output and stroke volume during the trial. Conversely, patients who fail weaning often fail to appropriately increase cardiac output during weaning.
The increased respiratory work of weaning and need for increased oxygen delivery can precipitate ischemia in the presence of high-grade coronary stenoses. In addition, the increased work of breathing associated with weaning constitutes a significant stress test with elevations of plamsa cortisol, glucose, and insulin and increased release of catecholamines.
The transition from positive-pressure ventilation to the negative swings in intrathoracic pressure seen during an SBT may precipitate cardiogenic pulmonary edema. Negative intrathoracic pressure results in increases in both cardiac preload and afterload.
Positive fluid balance has been associated with weaning failure. There is increasing recognition that psychological factors may contribute to difficulty weaning. These may be in the setting of underlying psychiatric disease e.
Psychological factors can cause physiologic abnormalities e. Conversely, psychological distress can produce findings that mimic those seen with weaning failure for other reasons. Signs and symptoms thought to be indicative of weaning failure such as agitation, diaphoresis, tachycardia and tachypnea can also be a result of psychological distress.
Once patients have developed signs of intolerance to weaning, they should immediately be returned to full ventilatory support. A well-monitored weaning trial with immediate return to full ventilatory support at the first signs of intolerance does not appear to result in respiratory muscle fatigue.
This observation is important because it means that another attempt at weaning after appropriate efforts to identify and treat the cause can be safely initiated within the next 24 hours.
In contrast, should the patient not be rapidly returned to full ventilatory support, there is a risk that fatigue may develop. Under those circumstances, the patient should be rested on full ventilatory support for at least 24 hours before further attempts at weaning. Failure to do so increases the likelihood that future attempts will fail. Further attempts at weaning are likely to be unsuccessful until the underlying pathophysiologic cause for weaning failure has been addressed.
See Table I. The clinician should maintain a high index of suspicion that the cardiopulmonary interaction may be limiting weaning, especially in patients with underlying cardiac disease. Treatment of cardiogenic pulmonary edema should consist of diuretics and afterload reduction. When cardiac ischemia is present, nitrates and beta blockers should be used. In general, beta-1 selective agents are well tolerated in patients with underlying COPD. If concern about using such agents is present, a trial of the short-acting agent esmolol may be considered.
If beta blockade results in increased airflow obstruction, inhaled anticholinergics should be administered. Because positive-pressure ventilation can effectively decrease preload and afterload, non-invasive ventilation may be used after extubation in patients at high risk for cardiogenic pulmonary edema. Psychological factors should be considered in patients with underlying psychiatric disease or when delirium or any process leading to abnormal mental status is present.
Psychological factors should be considered when extensive evaluation cannot detect a pathophysiologic explanation in patients failing weaning trials. Uncontrolled observations suggest that interventions such as biofeedback, relaxation techniques and hypnosis may be beneficial in some patients. Similarly, treatment for depression may be helpful, though the ideal agent has not been identified. Treatment of delirium using haloperidol or olanzepine may facilitate weaning. Dexmedetomidine appears to be associated with less delirium and shorter time to extubation compared to benzodiazepines.
Protocols provide a standard approach to the weaning process and have been shown to reduce weaning time and total duration of mechanical ventilation. 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. How Does a Ventilator Work? Who Needs a Ventilator? Risks of Being on a Ventilator Patients on ventilators run a higher risk of developing pneumonia because of bacteria that enters through the breathing tube.
Eating While on a Ventilator The breathing tube will prevent the patient from eating normally, so a different tube that provides nutrients, may be inserted into their vein. Your Care Will Involve a Team Approach The medical team that closely monitors patients on a ventilator includes: doctors, nurses, respiratory therapists, X-ray technicians, and more.
Will the Ventilator be Painful? Ventilator Weaning Process Weaning is the process of taking someone off of a ventilator, so that they may begin to breathe on their own.
Other tests, such as X-rays and blood draws, may be done to measure oxygen and carbon dioxide levels sometimes called blood gases. The goal is for patients to be awake and calm while they are on a ventilator, but that can sometimes be difficult; many require light sedation for comfort, Dr.
Ferrante says. Although we try to avoid sedation as much as possible, particularly in delirious patients, we may have to give some sedation to prevent people from causing self-harm, like pulling out the breathing tube. Ferrante adds. Typically, most patients on a ventilator are somewhere between awake and lightly sedated. However, Dr. This is called prone positioning, or proning, Dr. We are using this a lot for COVID patients on a ventilator, and for those who are in the hospital on oxygen.
Some people may need to be on a ventilator for a few hours, while others may require one, two, or three weeks. If a person needs to be on a ventilator for a longer period of time, a tracheostomy may be required. AU is offering a genuine alternative to a long term stay in Intensive Care in a home care environment. Check out their website here www. Your job is to educate yourself quickly how you can have control, power and influence.
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