OVERVIEWThe respiratory therapist (RT) should evaluate daily a patient’s readiness to wean or the ability to be liberated from mechanical ventilation. The most common readiness to wean factors include, but are not limited to:undefined#ref3">3,4 Show
Standard weaning criteria (SWC) is used to evaluate the patient’s respiratory muscle strength and endurance and to predict the patient’s ability to successfully wean from mechanical ventilation. The most common and effective method is the spontaneous breathing trial (SBT). The SBT is a period that the patient breathes without any ventilatory support or minimal inspiratory pressure support.4,5 The amount of time to remain on an SBT varies but the typical range is 30 to 120 minutes.3,4 During the SBT, the RT observes the patient’s spontaneous breathing parameters such as tidal volume (VT), respiratory frequency (f), minutes volume, and the rapid shallow breathing index (RSBI). Spontaneous tidal volume (VTS) is a measure of ventilation and respiratory muscle endurance. The threshold for VTS is greater than 5 ml/kg.3 The threshold for minute volume is not clear, but most experts recommend that it be in the range of 10 to 12 L/min for successful weaning.4 The RSBI is the ratio of f/VT, and this value is used to gauge respiratory muscle fatigue during the SBT. If the RSBI is less than 105, it predicts successful weaning.1 If the RSBI is greater than or equal to 105, the patient may not be ready to wean from mechanical ventilation.4 These SWC are typically observed during the SBT performed on the mechanical ventilator. Additionally, there are a variety of SWC that may be helpful to determine readiness to wean in patients who have been on mechanical ventilation for an extended period or have other conditions that make it more difficult to wean from the ventilator.3 These SWC maneuvers may offer more information about respiratory muscle strength and endurance, especially in patients who are older, debilitated, or weak. These criteria may help determine the presence of respiratory muscle fatigue after a weaning period and predict a successful weaning and extubation outcome. Negative inspiratory force (NIF) may also be called maximum inspiratory force (MIF) or maximal inspiratory pressure (MIP). The measurement of NIF is effort independent, meaning that the patient does not have to cooperate. The threshold used to predict mechanical ventilation weaning success is less than or equal to –20 cm H2O to –30 cm H2O.3 Because this is an effort-independent measurement, the value is reliable with good technique, unless factors such as central respiratory drive impairment, sedation, a cuff leak, or respiratory muscle fatigue are present. Maximum expiratory pressure (MEP), also referred to as positive expiratory pressure (PEP), may be measured to evaluate the patient’s ventilatory muscle strength. The threshold used to predict successful weaning is greater than 60 cm H2O.4 It provides information about the patient’s ability to cough and clear secretions. It may be used in conjunction with the NIF to predict successful ventilator weaning and extubation. Vital capacity (VC) is also a measure of respiratory muscle endurance or reserve or both. A fatigued patient is unable to triple or even double the size of a breath. The threshold for VC is greater than or equal to 10 to 15 ml/kg (at least two to three times VTS).3 Beyond SWC, other factors that may affect the patient’s ability to successfully wean from mechanical ventilation include sedation, psychologic status, level of consciousness, and nutrition factors.3 All SWC are best used in combination with overall clinical assessment to determine the appropriateness of mechanical ventilation weaning and extubation.3 EDUCATION
ASSESSMENT AND PREPARATIONAssessment
Preparation
PROCEDURE
Spontaneous Breathing Trial (SBT)
Additional SWCAdditional SWC may be helpful to determine readiness to wean in patients who have been on mechanical ventilation for an extended period or have other conditions that make it more difficult to wean from the ventilator.
Completing the Procedure
MONITORING AND CARE
EXPECTED OUTCOMES
UNEXPECTED OUTCOMES
DOCUMENTATION
OLDER ADULT CONSIDERATIONS
REFERENCES
ADDITIONAL READINGSMacIntyre, N.R. and others. (2001). Evidence-based guidelines for weaning and discontinuing ventilatory 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, 120(6), 375S-395S. doi:10.1378/chest.120.6_suppl.375s Frazier, S.K. (2017). Chapter 33: Weaning mechanical ventilation. In D.L. Wiegand, (Ed), AACN procedure manual for high acuity, progressive and critical care (7th ed., pp. 277-285). St. Louis: Elsevier. Elsevier Skills Levels of Evidence
When should a patient be weaned off a ventilator?Weaning a patient from a ventilator occurs when the condition of the patient improves and a decision is made to remove them from the ventilator through a trial of spontaneous breathing through the endotracheal tube and eventually extubation (removal of the tube).
How do you wean a patient from mechanical ventilation?Techniques include:. gradual reduction in mandatory rate during intermittent mandatory ventilation.. gradual reduction in pressure support.. spontaneous breathing through a T-piece.. spontaneous breathing with ventilator on 'flow by' and PS=0 with PEEP=0.. How do you determine if the patient is capable of being separated from the ventilator?Suppose your patient demonstrates that she can be separated from the ventilator. Should she be extubated? When a patient passes a spontaneous breathing trial, they are ready to be separated from the ventilator. In other words, they no longer need the ventilatory or oxygen support of the machine at their bedside.
How do you know when a patient is ready to be extubated?Medical staff will assess the readiness of the neonate for extubation. This will include deeming the patient as low-risk for re-intubation. Common signs the patient is ready for extubation: Patient has tolerated weaning of sedation, ventilator settings, and requires minimal oxygen supplementation.
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