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Abstract

Objective:

To determine the risk factors for the need of tracheostomy after cervical spinal cord injury (CSCI) at the acute stage.

Methods:

The authors retrospectively reviewed 294 patients with acute traumatic CSCI in Xinqiao Hospital between 2012 and 2016 and analyzed the factors postulated to increase the risk for tracheostomy, including patient’s age, neurological impairment scale grade and level, smoking history, combined injury, and surgical intervention. Logistic regression analysis was used to identify independent risk factor for the need of tracheostomy.

Results:

Of 294 patients, 52 patients received tracheostomy (17.7%). The factor identified by demographics and outcomes were smoking history, cause of injury, neurological impairment scale grade and level, and combined dislocation. A multiple logistic regression model demonstrated that age of 60 years older, combined facet dislocation, C4 level high, and the American Spinal Injury Association (ASIA) A and B scale were predictive of need for tracheostomy on 95% occasions.

Conclusion:

The high age of 60 years, combined facet dislocation, C4 level high, and ASIA A and B scale are indispensable to predict the need for tracheostomy in patients with CSCI at the acute stage.

Keywords

cervical spinal cord injury risk factors tracheostomy

Introduction

Traumatic cervical spinal cord injury (CSCI) may cause disability and mortality in both acute and chronic stages.¹ Respiratory complications are the first leading causes of death of CSCI.² Many patients with acute CSCI require a period of mechanical ventilation with tracheostomy.^3,4 Several authors have investigated the risk factors for tracheostomy in traumatic CSCI, including patients’ age, neurological severity, neurological level, forced vital capacity, and volume of pulmonary secretion.^4
–6 However, there are several limitations to these studies, such as retrospective study, relatively small sample size, different epidemiological features, diverse indication for tracheostomy, and different statistical models. Single center experiences have reported conflicting incidence rates and confounders of risk factors. Therefore, the multicenter clinical series studies with local epidemiological feather should be advised. The purpose of this retrospective study was to determine the risk factors of tracheostomy in a relatively large sample of patients with acute phase of CSCI in data based on a Chinese hospital.

Materials and methods

A total of 294 patients with traumatic CSCI were treated at the Department of Orthopedics of Xinqiao Hospital from January 2012 to December 2016. All patients were admitted in the first 3 days after injury. CSCI was evaluated according to the American Spinal Injury Association (ASIA) impairment classification.⁷ The criteria for tracheostomy in this series basically followed the established protocol by which the patients were chosen to undergo tracheostomy.^3,4 However, the decision to perform tracheostomy was based independently on the judgment of the attending surgeon caring for the patient.

Data analyzed included patient age, gender, cause of injury (road traffic accidents, falls from height, and other causes), history of smoking, ASIA scale (grades A, B,C, and D), the level of injury (above C4 and C5–C8), associated injuries (thoracic and abdominal injury, pelvic, and extremity fracture), and cervical facet dislocation. Patients who required tracheostomy were compared with patients who did not. All data are presented as percentage, which was calculated out of subgroup total (N) for each subgroup analysis.

Statistical analyses were performed using SPSS13.0 software (SPSS Inc., Chicago, Illinois, USA). Intergroup comparisons were performed by χ ² test to determine the independent risk factors of the placement of tracheostomy and to calculate the p value. The values of p ≤ 0.05 were considered to be statistically significant. Each factor identified by χ ² test might have a confounder; therefore, in order to adjust the confounder, the significant factors were reanalyzed using a multiple logistic regression model to determine the independent predictors of the placement of tracheostomy and to calculate both the p values and the odds ratios (ORs)

Results

All 294 patients were identified during the 5-year study period. The patients (243 male and 51 females) ranged from 10 years to 82 years of age (mean age, 48.9 ± 14.7 years). All injuries were the result of blunt trauma. Fifty-two of the 294 patients received tracheostomy (17.7%). Demographic and clinical data are presented in Table 1. The initial results using a simple logistic regression determined that smoking (p < 0.003), injury causes (p < 0.008), level of injury (p < 0.001), ASIA scale (p < 0.001), and combined facet dislocation (p < 0.001) were statistically significant factors that increased the incidence of tracheostomy (Table 1).

Table 1.

Demographics/outcomes for tracheostomy versus no tracheostomy.

	Tracheostomy, n (n%)	No tracheostomy, n (n%)	χ ²	p
Sex			0.665	0.415
Male	45 (18.5)	198 (81.5)
Female	7 (13.7)	44 (86.3)
Smoking			9.05	<0.003
Smoking	28 (26.7)	77 (73.3)
No smoking	24 (12.7)	165 (87.3)
Age (years)			2.81	0.245
<40	11 (14.7)	64 (85.3)
40–60	23 (16.0)	121 (84.0)
>60	18 (24.0)	57 (76.0)
Cause			13.76	<0.008
Height fall	28 (24.6)	86 (75.4)
Traffics	8 (11.3)	63 (88.7)
Fall	7 (9.6)	66 (90.4)
Crash	8 (33.3)	16 (66.7)
Others	1 (8.3)	11 (91.7)
Level			31.59	<0.001
C1–C4	34 (35.8)	61 (64.2)
C5–C8	18 (9.0)	181 (91.0)
ASIA			80.70	<0.001
A	28 (59.6)	19 (40.4)
B	10 (30.3)	23 (69.7)
C	9 (11.7)	68 (88.3)
D	5 (3.6)	123 (96.4)
Dislocation			15.58	<0.001
Yes	42 (25.5)	123 (74.5)
No	10 (7.8)	119 (92.2)
Combined injury			1.06	0.303
Yes	37 (19.4)	154 (80.6)
No	15 (14.6)	88 (85.4)
Total	52	242

ASIA: American Spinal Injury Association.

An analysis was performed in both the tracheostomy group and no tracheostomy group to adjust the confounder. Dichotomous variables were entered into the multiple logistic regression models to identify independent predictors for tracheostomy. Age of 60 years older (p = 0.010, OR = 4.809), combined facet dislocation (p = 0.03, OR = 0.230), level above C4 (p = 0.001, OR = 12.863), ASIA A scale (p < 0.001, OR = 29.554), and ASIS B scale (p < 0.002, OR = 7.894) were found to be independent predictors for the need for tracheostomy (Table 2).

Table 2.

Risk factors for tracheostomy after multiple logistic regressions.

	PRC	PRC SE	Wald	p	OR	95% CI
Age			7.618	0.022
40–60	0.569	0.517	1.212	0.271	1.767	0.641–4.866
>60	1.570	0.608	6.665	0.010	4.809	1.460–15.843
Smoking	0.730	0.400	3.328	0.068	2.075	0.947–4.546
Combined injury	0.923	0.454	4.136	0.052	2.517	1.034–6.126
Dislocation	1.469	0.492	8.929	0.003	0.230	0.088–0.603
Level	−1.182	0.405	8.506	0.004	0.307	0.139–0.679
C1–C4	2.178	0.613	16.530	0.001	12.863	3.588–29.752
C5–C8	1.532	0.592	3.351	0.063	2.357	0.921–4.203
ASIA			36.482	<0.001
A	3.386	0.603	31.534	<0.001	29.554	9.064–96.359
B	2.066	0.660	9.809	<0.002	7.894	2.166–28.760
C	1.143	0.607	3.550	0.060	3.138	0.955–10.308
Constant	−2.435	0.925	6.927	<0.008	0.088

PRC: partial regression coefficient; PRC SE: partial regression coefficient standard error; OR: odds ratio; CI: confidence interval; ASIA: American Spinal Injury Association.

Discussion

Tracheostomy in traumatic CSCI has been reported with regard to potential benefits, timing, and resource use and has been investigated to identify predictors of the need for tracheostomy.^{3
–5,8

–12} However, there are controversies about the definitive risk factors for tracheostomy in traumatic CSCI. For example, complete cord lesion, premorbid lung diseases, and patient age have been reported as significant risk factors for the need of tracheostomy by several authors,^4,13,14 but they were not identified as predictors by some authors.^3,15 In this study, using a simple logistic regression model, we found that smoking, injury causes, level of injury, ASIA scale, and combined facet dislocation were statistically significant factors that increased the incidence of tracheostomy (Table 1). In order to elucidate the significant risk factors for tracheostomy, we conducted a multivariate analysis to adjust for confounding factors. In our series, four factors (age of 60 years older, combined facet dislocation, level above C4, and ASIA A and B scale) were found to be independent predictors for the need of tracheostomy (Table 2). In other studies, with multivariate analysis, a high injury severity score, forced vital capacity, and complete CSCI have been reported to be independent predictors for the need to perform either tracheostomy or intubation.^4,5,16

Several authors have demonstrated that complete cord lesion and above the level of C4 injury were significant risk factors for mechanical ventilation in patients with CSCI.^4,5,8,9,17 Similarly, in this study, AISA A and B and above the level of C4 injury were revealed to be a significant predictor of the need for tracheostomy. The occurrence of respiratory dysfunction is related to denervation of the phrenic nerve and intercostal nerve after CSCI. The phrenic nucleus is located in the center of C4 anterior column. The diaphragm is innervated by the phrenic nerve and is the main driving force for respiratory movements providing 65% of the tidal volume during normal breathing.¹⁸ When high-level (C1–C4) and complete CSCI occurs, the phrenic nerve is involved, causing loss of spontaneous respiration and respiratory failure.

There are controversies around the relationship between patient age and the need for tracheostomy in patients with CSCI. Several authors found that age above 50 years was one of the inhibitory factors for weaning from a ventilator and identified that age older than 69 years was a significant risk factor for tracheostomy.^5,13,19 However, some authors reported no relationship between patient age and the need for intubation and respiratory complications.^14,16 The present study demonstrated that the age of 60 years older was predictive of the need for tracheostomy in 95% of cases. The sufficient sample size may be the key role for the argument.

One intriguing finding of the present study is the fact that combined facet dislocation is indispensable to predict the need for tracheostomy in patients with CSCI at the acute stage. CSCI patients with facet dislocation tended to present with a more severe degree of initial injury and displayed less potential for motor recovery.²⁰ Approximately, 75% of CSCI patients with facet dislocation were diagnosed with AISA A and B at presentation to hospital.²¹ Therefore, cervical facet dislocation may act as an indicator of SCI and its severity and as a significant risk factor for intensive respiratory disease treatment in patients with CSCI.

There are several limitations to this study. First, it was a retrospective study. Second, the sample size was relatively small. Third, the indications for intubation or tracheostomy for the patients with SCI vary between institutions. Finally, this study reflected the experience at a single specialized spinal injuries center with local epidemiological characteristics. Despite these limitations, this study provides important epidemiologic data on predictors for tracheostomy in patients with CSCI.

In conclusion, a high age, combined facet dislocation, C4 level high, and ASIA A and B scale were independently associated with the need for tracheostomy in patients with CSCI at the acute stage. Based on these results, we recommend early tracheostomy should be considered in patients with these risk factors.

Footnotes

Declaration of conflicting interests

The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The author(s) received no financial support for the research, authorship, and/or publication of this article.

ORCID iD

Zhengfeng Zhang

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