SESSION TITLE: Respiratory Support Posters
SESSION TYPE: Original Investigation Poster
PRESENTED ON: Wednesday, October 30, 2013 at 01:30 PM - 02:30 PM
PURPOSE: We have shown that an inspiratory pattern in which each inspiration consists of an initial intercostal muscle contraction followed by a paroxysmal diaphragmatic contraction (dome and spike) reflects brainstem dysfunction with discoordination of the diaphragm and chest wall muscles. This dysfunction can cause respiratory failure despite good lung and respiratory muscle function. This study was conducted to determine its natural history and clinical significance.
METHODS: Design: observational study Ten patients transferred from the ICU for weaning were evaluated. All had been sedated until their transfer at which time their Ramsey scores were all between 5 and 6. Oxygenation and mechanics were evaluated daily in each patient. Inspiratory flow pattern and ability to breathe were evaluated daily with spontaneous breathing trials using no CPAP or pressure support (PSV).
RESULTS: All ten patients displayed dome and spike inspiration at the initial evaluation (day1). By day 3 the mean Ramsey score had improved to 2.5 in 8 of the patients but their respiratory pattern remained very abnormal with an unlabored tachypnea at 38 to 40b/m which was neither suppressable by PSV nor sustainable. By day 7 the mean Ramsey score of these 8 patients had improved to 2.2 and their inspiratory pattern had also improved with rates of 30b/m or less. All were successfully weaned at this time. No changes in mechanics or gas exchange had occured. The remaining two patients suffered from anoxic encephalopathy and had no change in either Ramsey score or inspiratory flow pattern during the week of observation. Neither became capable of independent ventilation.
CONCLUSIONS: The respiratory center dysfunction causing dome and spike inspiration can be caused by CNS disease or by sedatives. It does not correlate well with cortical function. It is capable of causing respiratory failure despite good lung and muscle function. When caused by sedation this respiratory center dysfunction persists longer than cognitive suppression and much longer than is generally recognized. Dome and Spike inspiration in the absence of sedation predicts a poor prognosis for weaning.
CLINICAL IMPLICATIONS: The spontaneous inspiratory air flow pattern and other measures of brainstem function should be used in addition to consciousness scales in monitoring the depth of sedation in the mechanically ventilated patient. Sedation must be eliminated or at least minimized for several days prior to any meaningful attempt at weaning in complicated cases.
DISCLOSURE: The following authors have nothing to disclose: William Marino
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