The Science Journal of the American Association for Respiratory Care

2004 OPEN FORUM Abstracts

WEANING THE VENTILATOR DEPENDENT PATIENT WITH WEST NILE VIRUS

Wendy Woods Dedrick, RRT, Melanie Ziolkowski, BSN, RRT, Susan Sampson, CRTT Eric S. Yaeger, MD Kindred Hospital Denver, Denver, Colorado

Background: The West Nile Virus (WNV) made a significant impact in the United States for the first time in 1999. According to the CDC, Colorado had the highest reported WNV activity in the year 2003 with a total of 2947 cases. The full clinical spectrum of WNV is highly variable. Approximately one in 150 cases of WNV infection results in severe neurologic disease including meningitis, encephalitis, or meningoencephalitis that may lead to permanent neurological damage of varying degrees and/or death. Kindred Hospital Denver (KHD), a Long Term Acute Care (LTAC) hospital, admitted a total of 15 WNV patients (PT) during the year 2003. Fourteen out of the 15 PT were admitted with a diagnosis of respiratory failure (RF), ventilator dependency, and paralysis. This study was conducted to determine if the different types of clinical manifestations of WNV infection (encephalitis with or without flaccid paralysis and meningoencephalitis with or without flaccid paralysis) influenced weaning success from mechanical ventilation (MV) based on objective measures of respiratory muscle strength using rapid shallow breathing index (RSBI) and negative inspiratory force (NIF).

Method: Retrospective chart review was conducted of PT admitted to KHD in 2003 with a diagnosis of WNV. All PT had documented positive serological evidence of WNV infection. Data collected was PT history and physical, age, date of documented positive serological evidence of WNV, degree of paralysis, average RSBI and NIF upon admission and average RSBI and NIF before successful liberation from MV or discharge, weaning techniques, average number of days to SBT, and average number of days to liberation from MV.

Results: A total of 15 PT, mean age 65 (range 27-84), were admitted to KHD with documented serological evidence of WNV. Fourteen of the PT were admitted with RF, ventilator dependency, and paralysis. One patient was admitted on room air for rehabilitation. The clinical manifestations in the representative sample are as follows: 3 PT diagnosed with meningoencephalitis with flaccid paralysis, 1 patient with meningoencephalitis without flaccid paralysis, 5 PT diagnosed with encephalitis with flaccid paralysis and 5 PT diagnosed with encephalitis without flaccid paralysis. Eight of the 14 PT were successfully liberated from MV. Admission respiratory muscle strength demonstrated an average RSBI 104 and NIF –22 in successfully weaned PT. Further, respiratory muscle strength improved before successful liberation from MV with an average RSBI 89 and NIF –28. Upon admission, non-weanable PT exhibited an average RSBI 219 and NIF –12 and upon discharge average RSBI 260 NIF –14. Modalities for successfully weaning this difficult patient population included the utilization of Transtracheal Augmented Ventilation (TTAV) during SBT for 6 PT. Two PT utilized the trach collar for SBT weans. Average number of days to SBT was 14, and average number of days to liberate the 8 PT from MV was 30. One hundred percent of PT diagnosed with encephalitis or meningoencephalitis without flaccid paralysis and 40% of PT diagnosed with encephalitis with flaccid paralysis were successfully liberated from MV. None of the PT diagnosed with meningeoencephalitis with flaccid paralysis were successfully weaned.

Conclusion: Long-term outcome of PT with WNV is variable. KHD overall weaning success rate for PT admitted with WNV, RF, and paralysis was 57%. The different clinical manifestations of WNV influenced the wean success rate. No PT diagnosed with meningoencephalitis and flaccid paralysis was able to wean successfully from MV. However, even PT with poor respiratory mechanics could be weaned utilizing a multidisciplinary approach. Further studies are needed to corroborate the results due to the small number of PT in this descriptive analysis.

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