Resp Care
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Weaning comprises 40 percent of the duration of mechanical ventilation. Protocols to reduce weaning time and to identify candidates at the earliest possible moment have been introduced to reduce complications and costs. Increased demand for mechanical ventilation, an increase in the number of patients requiring prolonged ventilation, and resource/staffing issues have created an environment where automated weaning may play a role. ⋯ Preliminary research has demonstrated mixed results. Current systems continue to be evaluated in different patient populations and environments. Automated weaning is part of the ICU armamentarium, and identification of the patient populations most likely to benefit needs to be further defined.
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Noninvasive ventilation (NIV) may reduce the need for intubation in acute respiratory failure (ARF). However, there is no standard method to predict success or failure with NIV. The rapid shallow breathing index (RSBI) is a validated tool for predicting readiness for extubation. We evaluated the ability of the RSBI to predict failure of NIV and mortality in ARF. ⋯ An aRSBI of > 105 is associated with need for intubation and increased in-hospital mortality. Whether patients with an elevated aRSBI could also have benefitted from an increase in NIV settings remains unclear. Validation of this concept in a larger patient population is warranted.
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Mechanical ventilation is a life-saving supportive therapy, but it can also cause lung injury, diaphragmatic dysfunction, and lung infection. Ventilator liberation should be attempted as soon as clinically indicated, to minimize morbidity and mortality. The most effective method of liberation follows a systematic approach that includes a daily assessment of weaning readiness, in conjunction with interruption of sedation infusions and spontaneous breathing trials. ⋯ Checklists can be used to reinforce application of the protocol, or possibly in lieu of one, particularly in environments where the caregiver-to-patient ratio is high and clinicians are well versed in and dedicated to applying evidence-based care. There is support for integrating best-evidence rules for weaning into the mechanical ventilator so that a substantial portion of the weaning process can be automated, which may be most effective in environments with low caregiver-to-patient ratios or those in which it is challenging to consistently apply evidence-based care. This paper reviews evidence for ventilator liberation protocols and discusses issues of implementation and ongoing monitoring.
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The ventilator discontinuation process is an essential component of overall ventilator management. Undue delay leads to excess stay, iatrogenic lung injury, unnecessary sedation, and even higher mortality. On the other hand, premature withdrawal can lead to muscle fatigue, dangerous gas exchange impairment, loss of airway protection, and also a higher mortality. ⋯ More recent developments have focused on the utility of computer decision support to guide these processes and the importance of linking sedation reduction protocols to ventilator discontinuation protocols. These guidelines are standing the test of time, and practice patterns are evolving in accordance with them. Nevertheless, there is still room for improvement and need for further clinical studies, especially in the patient requiring prolonged mechanical ventilation.
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Elevated dead space fraction (the ratio of dead space to tidal volume [V(D)/V(T)]) is a feature of ARDS. PEEP can partially reverse atelectasis, prevent alveoli recollapse, and improve lung compliance and gas exchange in patients with ARDS. However, whether V(D)/V(T) variables have a close relationship with PEEP and collapse alveolar recruitment remains under recognized. Meanwhile, few clinicians titrate PEEP in consideration of changes in V(D)/V(T). Therefore, we performed the study to evaluate V(D)/V(T), arterial oxygenation, and compliance changes during PEEP titration following lung recruitment in ARDS patients. ⋯ A significant change of V(D)/V(T), compliance and arterial oxygenation could be induced by PEEP titration in subjects with ARDS. Optimal PEEP in these subjects was 12 cm H₂O, because at this pressure level the highest compliance in conjunction with the lowest V(D)/V(T) indicated a maximum amount of effectively expanded alveoli. Monitoring of V(D)/V(T) was useful for detecting lung collapse and for establishing open-lung PEEP after a recruitment maneuver.