Elsevier

Injury

Volume 46, Issue 7, July 2015, Pages 1317-1323
Injury

Synergistic impact of acute kidney injury and high level of cervical spinal cord injury on the weaning outcome of patients with acute traumatic cervical spinal cord injury

https://doi.org/10.1016/j.injury.2015.02.025Get rights and content

Abstract

Introduction

Respiratory neuromuscular impairment severity is known to predict weaning outcome among patients with cervical spinal cord injury; however, the impact of non-neuromuscular complications remains unexplored. This study was to evaluate possible neuromuscular and non-neuromuscular factors that may negatively impact weaning outcome.

Methods

From September 2002 to October 2012, acute traumatic cervical spinal cord injury patients who had received mechanical ventilation for >48 h were enrolled and divided into successful (n = 54) and unsuccessful weaning groups (n = 19). Various neuromuscular, non-neuromuscular factors and events during the intensive care unit stay were extracted from medical charts and electronic medical records. Variables presenting with a significant difference (p < 0.2) between these two groups were included in the univariate analysis. Following univariate analysis, those significantly different variables (p < 0.05) were subjected to multivariate logistic regression to identify independent predictors of unsuccessful weaning.

Results

Compared to successful weaning patients, unsuccessful weaning patients were older; more often had high level of cervical spinal cord injury (C1–3), lower pulse rates, and lower Glasgow Coma Scale score on admission, higher peak blood urea nitrogen, lower trough albumin, and lower trough blood leukocyte counts. Furthermore, unsuccessful weaning patients had a higher incidence of pneumonia, acute respiratory distress syndrome, shock and acute kidney injury during the intensive care unit stay. Multivariate logistic regression analysis revealed acute kidney injury and high level of cervical spinal cord injury were independent risk factors for failure of weaning. Importantly, patients with both risk factors showed a large increase in odds ratio for unsuccessful weaning from mechanical ventilation (p < 0.001).

Conclusions

The presence of acute kidney injury during the intensive care unit stay and high level of cervical spinal injury are two independent risk factors that synergistically work together producing a negative impact on weaning outcome.

Introduction

Cervical spinal cord injury is a devastating disease and may cause serious complications that require support from mechanical ventilation in an intensive care unit (ICU) [1], [2]. The complications mainly result from impairment of the neural control of respiratory muscles, the severity of which is correlated with the cervical level of the injury [3], [4]. This respiratory neuromuscular impairment is particularly disadvantageous to such patients when they need to be discontinued from ventilator [5]. Although the clinical management of cervical spinal cord injury patients has been greatly improved [2], [4], [6], these patients still have a high risk of weaning failure and some of them eventually become ventilator-dependent [7], [8]. Thus, weaning patients with cervical spinal cord injury from the ventilator remains a challenge for clinicians [1], [9].

Only a few studies have evaluated the predictors for cervical spinal cord injury patients who merit weaning from ventilation. A higher level of cervical spinal cord injury, an older age, and a lower Glasgow Coma Scale (GCS) score on admission have been reported to be associated with weaning failure in this patient population [8], [10], [11]. Additionally, negative inspiration force and forced vital capacity have been suggested to be weaning predictors in patients with high level of cervical spinal cord injury [11]. However, most of these weaning predictors, if not all, appear to be directly related to the respiratory neuromuscular impairment found in cervical spinal cord injury patients and thus it is not surprising that these risk factors exert a negative impact on weaning outcome. It is worth noting that, at ICU admission, or during an ICU stay, cervical spinal cord injury patients may develop various complications, such as acute kidney injury (AKI) [12], [13], electrolyte imbalance [14], [15], shock [13], [16], [17], and respiratory infection [13], [18]. All of these are secondary to or are not even related to cervical spinal cord injury-induced respiratory neuromuscular impairment. Importantly, many of these non-neuromuscular complications have been reported to be associated with a higher risk of weaning failure in ICU patients without cervical spinal cord injury [19], [20], [21]. However, whether these non-neuromuscular complications may work together with respiratory neuromuscular impairment to synergistically produce a negative impact on the weaning outcome of cervical spinal cord injury patients remains unknown.

The objectives of this study were, firstly, to identify respiratory neuromuscular and non-neuromuscular risk factors that may have a negative impact on weaning outcome among patients with acute traumatic cervical spinal cord injury, and, secondly, to evaluate any possible synergistic impacts of these two categories of risk factors on weaning outcome among these patients.

Section snippets

Design, setting and patients

This retrospective study was conducted at Taipei Veteran General Hospital, a 3000-bed tertiary medical centre. The study was approved by the Institutional Ethical Review Board of Taipei Veterans General Hospital (VGHTPE-IRB No. 201008001IC). Informed consent was not required for this observational study according to our institutional guidelines. Among patients admitted between September 2002 and October 2012, we identified by chart review patients who had suffered cervical spinal cord injury

Characteristics of the study patients

Over the 10-year study period, 523 patients were admitted with a diagnosis of traumatic cervical spinal cord injury and 139 patients were excluded according to the exclusion criteria. Of the remaining 384 patients, 146 patients did not develop respiratory failure, 151 patients received mechanical ventilation for less than 48 h, 11 patients died before successful weaning, and 3 patients were transferred to another hospital with the reason not being weaning failure (Fig. 1). The remaining 73

Discussion

Despite the fact that there have been major improvements to the therapy and critical care of patients with cervical spinal cord injury, the rate of unsuccessful weaning among this patient population still remains high [6], [7], [8]. In these circumstances, investigation of the predisposing risk factors related to unsuccessful weaning among patients with cervical spinal cord injury is of great interest [8]. In this study, we found that both a high level of cervical spinal cord injury and the

Conclusions

Our study demonstrates that the presence of AKI during the ICU stay together with a high level of cervical spinal cord injury are two independent risk factors that seem to work synergistically to produce a negative impact on weaning outcome among patients with acute traumatic cervical spinal cord injury. Our findings should be helpful to ICU physicians when they are refining the clinical managements of these patients and should also help when determining who merit weaning from ventilation. The

Conflict of interest statement

The authors declare that they have no conflict of interest.

Acknowledgments

The authors are grateful to Dr. Ralph Kirby, Department of Life Sciences, National Yang-Ming University, for his help in language editing. This study was supported by a grant NSC 101-2320-B-010-042-MY3 from National Science Council and a grant from Ministry of Education, Aim for the Top University Plan, Taiwan.

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