The Science Journal of the American Association for Respiratory Care

2005 OPEN FORUM Abstracts

SMALL OR LARGE TIDAL VOLUMES: THE DILEMMA OF SPINAL CORD INJURY

John H. Boynton Jr. RRT, Kenneth Hawkins RRT, and Keith Tansey, MD, PhD, Parkland Health and Hospital System and Spinal Cord Injury Program, UTSWMC, Dallas, Texas

Background: In this era of low tidal volume ventilation the ventilator management of the high spinal cord injured patient has been made more difficult. The need has been established to use low volume strategies (6cc/kg/pbw)1 when the lungs are "sick" and to use large tidal volumes (10-15cc/kg/pbw) 2 when the lungs are "well". However patients with spinal cord injury (SCI) may experience both "sick" and "well" lungs in their ventilatory course, what determines when the patient has transitioned from one state to the other is an important clinical question. We have developed a criterion for identifying and transitioning the high SCI patient, which facilitates liberation from the ventilator.

Method: In our Surgical /Trauma ICU we use a P/F (PaO2/FIO2) threshold of 300 as a cutoff value to distinguish between "sick" and "well" lungs in the high SCI patient. Until these patients reach a P/F of ≥ 300 they are managed using a low tidal volume strategy. Patients with a P/F ≥ 300 are transitioned to the high tidal volume strategy while assuring that plateau pressures of 35 cmH20 are not exceeded. Although Peterson2 used 20cc/kg for large tidal volume, the idea of volume and pressure must be looked at together, therefore we used a plateau of 35 as a maximum pressure to set the large tidal volumes and as a result we used (10-15cc/kg/pbw).

Results: We have liberated 3 patients from the ventilator using this strategy in no more than 17 days. The first patient was a C-5 level, the second was a C-4 level and the last patient was a C-2 level on the left, and a C-5 level on the right. The C-2 /C-5 patient took 17 days to liberate, the 2 other patients were liberated from the ventilator in less than 17 days. In Peterson's study 2 37.5 days was the avg. time to liberation for C3-4 level patients. We are continuing to collect data.

Conclusion: In this high SCI patient population we must be able to transition from the acute lung injured ARDS lung to the rehabilitation patient with normal "bellows" function. In our experience, the SCI patient will develop atelectasis and pneumonia unless they are able to expand their chest wall adequately and experience, as a result, a longer intubation time. While our data are preliminary and there needs to be more study done on this subject, we do believe our early results contribute to an important discussion in this area. The data on high tidal volumes in the high SCI patient is retrospective as is almost all SCI research data in this area, this does not mean it is not of clinical use however randomized controlled trials are needed. The rehabilitation aspects of medicine and critical care need to learn from each other in this patient population. We hope this contributes to the debate.

1. ARDS Net .Ventilation with lower tidal volumes as compared with traditional tidal volumes for acute lung injury and the acute respiratory distress syndrome (N EnglJ Med 2000;342:1301-8.)

2. Peterson WP, Barbalata L, Brooks CA, Gerhart KA, Mellick DC, Whiteneck GG. The effect of tidal volumes on the time to wean persons with high tetraplegia from ventilators. Spinal Cord 1999;37:284-88.

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