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| ==Weaning==
| | {{ACM}} |
| ===Overview===
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| Weaning of mechanical ventilator is gradual withdrawal of
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| ventilatory support through utilization of a variety of ventilator modes,
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| periods of total spontaneous ventilation, and appropriate rest periods for
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| muscle unloading. Discontinuation of mechanical ventilation should occur as
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| soon as the patient is able to protect his/her airway and sustain a
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| physiologically-competent minute ventilation while important indicators of
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| disease show resolution.
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| The plan of weaning is not static but requires
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| continual reassessment so that the particular ventilatory needs of the patient
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| are met while the disease process is corrected. Bedside measures of
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| cardiopulmonary function aid in the assessment of weaning fitness; these
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| should not take the place of careful bedside observation and "hands-on" care,
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| however. Patients should not be allowed to fatigue during weaning trials, and
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| interventions to ensure an adequate nutritional status and good bronchial
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| hygiene should be applied.
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| ===Criteria for Spontaneous Breathing Trial (SBT)===
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| Spontaneous Breathing trials assess patient’s ability to breathe without or with the least
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| respiratory support. In order to accomplish this, ventilators' modes are switched
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| from full respiratory support such as volume-assist control or pressure
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| control to ventilatory modes such as pressure support, continuous positive airway
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| pressure (CPAP), or ventilation with a T-piece (in which there is no positive endexpiratory
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| pressure). Typically, the patient is awake and not sedated during a trial of spontaneous breathing is initiated while the
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| The typical readiness criteria for SBT are:
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| *Respiratory Criteria
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| #PaO2>= '''60 mm hg''' ( FiO2<40-50,PEEP<5-8cm H2O)
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| #PaCo2 normal or base line
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| #the Patient able to initiate inspiratory effort
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| *Cardiovascular Criteria
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| #No evidence of myocardial ischemia
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| #HR<140/min
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| #BP normal without vasopressor or minimal vasopressor support
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| #Adequate mental status :''arousable/GCS.13''
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| *Absence of correctable comorbid conditions
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| #Patient is afebrile
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| #No significant electrolytes abnormalities
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| ===Patient Who Will Tolerate Weaning===<ref name="pmidDOI: 10.1056/NEJMra1203367">{{cite journal| author=Schmoldt A, Benthe HF, Haberland G| title=Digitoxin metabolism by rat liver microsomes. | journal=Biochem Pharmacol | year= 1975 | volume= 24 | issue= 17 | pages= 1639-41 | pmid=DOI: 10.1056/NEJMra1203367 | doi= | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=10 }} </ref>
| | [[File:Captura de Pantalla 2024-05-18 a la(s) 9.33.11 p.m..png]] |
| For a spontaneous-breathing trial to be successful, a patient must breathe spontaneously
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| with little or no ventilator support for at least 30 minutes '''without any of
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| the following:'''
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| # respiratory rate>35 breaths/min for more than 5 minutes
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| #an oxygen saturation <90%
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| #heart rate >140 beats per minute
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| #a sustained change in the heart rate of 20%
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| #systolic blood pressure >180 mm Hg or <90 mm Hg
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| #increased anxiety or diaphoresis
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| ===Rapid Shallow Breathing Index===
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| '''DEFINITION''' — The rapid shallow breathing index (RSBI) is the ratio of respiratory frequency to tidal volume (f/VT). As an example, a patient who has a respiratory rate of 25 breaths/min and a tidal volume of 250 mL/breath has an RSBI of (25 breaths/min)/(.25 L) = 100 breaths/min/L.
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| Patients who cannot tolerate independent breathing tend to breathe rapidly (high frequency) and shallowly (low tidal volume). Thus, they generally have a high RSBI.
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| • The RSBI was originally measured using a hand-held spirometer attached to the endotracheal tube while a patient breathed room air for one minute without any ventilator assistance.
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| The sensitivity is the probability that a patient who successfully weans will have an '''RSBI <105'''
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| breaths/min/L and the specificity is the probability that a patient who fails weaning will have
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| an '''RSBI ≥105''' breaths/min/L. The positive predictive value is the probability of successfully
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| weaning when the RSBI is <105 breaths/min/L and the negative predictive value is the
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| probability of failing weaning when the RSBI is >105 breaths/min/L.
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| ===Risk Factors For Unsuccessful Weaning ===
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| #Failure of two or more consecutive spontaneous-breathing trials
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| #Chronic heart failure
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| #Partial pressure of arterial carbon dioxide >45 mm Hg after extubation
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| #More than one coexisting condition other than heart failure
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| #Weak cough
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| #Upper-airway stridor at extubation
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| #Age ≥65 yr
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| #APACHE II score >12 on day of extubation(Acute Physiology and Chronic Health Evaluation (APACHE II)range from 0 to 71, with higher scores indicating greater impairment.)
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| #Patient in medical, pediatric, or multispecialty ICU
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| #Pneumonia as cause of respiratory failure
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