Early Versus Late Tracheostomy in Patients With Acute Traumatic Spinal Cord Injury: A Systematic Review and Meta-analysis : Anesthesia & Analgesia

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Review Articles: Meta Analysis

Early Versus Late Tracheostomy in Patients With Acute Traumatic Spinal Cord Injury: A Systematic Review and Meta-analysis

Mubashir, Talha MD*; Arif, Abdul A. BSc; Ernest, Prince MD*; Maroufy, Vahed PhD; Chaudhry, Rabail MD§; Balogh, Julius MD*; Suen, Colin MD, PhD§; Reskallah, Alexander MD*; Williams, George W. MD*

Author Information
doi: 10.1213/ANE.0000000000005212

Abstract

KEY POINTS

  • Question: Does an early tracheostomy improve outcomes in patients with acute traumatic spinal cord injury (SCI)?
  • Findings: Based on the available data, tracheostomy within the first 7 days of SCI or tracheal intubation results in a shorter duration of intensive care unit (ICU) length of stay and ventilator days and may decrease in-hospital mortality.
  • Meaning: Early tracheostomy may be beneficial in acute SCI patients, but the available data are of low quality; moreover, future studies should aim to identify factors for candidates for early tracheostomy.

Tracheostomy is a common procedure done in the intensive care unit (ICU) and is often used when patients need prolonged mechanical ventilation, which includes individuals with acute traumatic spinal cord injuries (SCIs). SCIs often result in impairments in respiration that may lead to a weak cough, increased risk of infection, and death.1 In such patients, tracheostomy can be performed to potentially reduce the duration of mechanical ventilation and decrease the risk of respiratory complications.2

Some studies have demonstrated that early tracheostomy in acute SCI is beneficial in shortening the ICU length of stay (LOS)3–8 and the duration of mechanical ventilation4–8 and may decrease mortality.9 On the contrary, other studies have refuted these claims and have shown no significant differences in outcomes, especially mortality and pneumonia rates, with respect to tracheostomy timing.4–8,10 Differences in patient characteristics, definitions of “early” and “late” tracheostomy, and a lack of objective assessment of the severity and level of spinal injuries are some methodological limitations among these studies. Nevertheless, positive effects of early tracheostomy have also been demonstrated in individuals with traumatic brain injuries (TBIs); however, these studies too are confounded with similar limitations.11–13 A recent meta-analysis on the assessment of optimal tracheostomy timing in patients with TBI found reduced mean duration of ICU LOS and mechanical ventilation by 2.5 and 2.7 days, respectively, while mixed results were noted for mortality at ICU or hospital discharge and between 28 days and 1 year from discharge.14

Tracheostomy is, however, still an invasive procedure and carries the risk of airway stenosis, hemorrhage and infections at the surgical site, pneumothorax, and subcutaneous emphysema.15 Hence, the decision to convert an endotracheal intubation to a tracheostomy requires careful assessment of the risks and benefits of the procedure and is dependent on the physician’s professional judgment. The optimal timing for tracheostomy and the identification of specific SCI patients who may benefit from an early tracheostomy remain unknown.

To our knowledge, this is the first systematic review and meta-analysis to assess tracheostomy timing and outcomes in patients with acute traumatic SCI. This review aims to determine the optimal timing of tracheostomy and evaluate potential subsequent beneficial effects by comparing early versus late tracheostomy in patients with SCI.

METHODS

Study Design and Registration

The protocol of this review was registered in the Open Science Framework Registry (DOI: 10.17605/OSF.IO/APWT9). The Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines were followed (Supplemental Digital Content 1, File 1, https://links.lww.com/AA/D196).16

Inclusion and Exclusion Criteria

The selection criteria included all studies on adult patients (age ≥18 years) with acute traumatic SCI who underwent subsequent early or late percutaneous or surgical tracheostomy. Early tracheostomy was defined as either <7 or <10 days (≤7 or ≤10 days) after patient admission or after initiation of mechanical ventilation, whereas late was defined as any time outside the early period (>7 or >10 days). The tracheostomy timing cutoff between early and late was preselected according to commonly reported timing in previously published literature.17 We considered the following types of studies: experimental, cohort, cross-sectional, case–control, and case series. Studies that reported concomitant TBI in the study population were excluded. Only English language articles were included.

Outcomes

The primary outcomes were in-hospital mortality and ICU LOS between early and late tracheostomy patients with acute traumatic SCI. Deaths reported after patient discharge were not included in the risk of mortality analysis. Secondary outcomes included duration of mechanical ventilation, pneumonia rates (ie, ventilator-associated pneumonia or hospital-acquired pneumonia), hospital costs, and posttracheostomy complications among early and late tracheostomy groups.

Information Sources and Search Strategies

We searched Medline (Ovid), PubMed (non-Medline records only), Embase, Cochrane Central, Cochrane Database of Systematic Reviews, and PsycINFO. ClinicalTrials.gov and the International Clinical Trials Registry Platform were searched for ongoing or recently completed but unpublished studies. To capture gray literature, we included conference abstracts that included detailed statistics on at least one of our primary or secondary outcomes. The search was done from database inception up until October 14, 2019. A combination of keywords for SCI and tracheostomy was incorporated into our search strategy. In addition, the reference lists of eligible studies and review articles were hand searched to acquire trials potentially missed from the original search. The searched terms and detailed search strategy in Medline are given in Supplemental Digital Content 2, Table S1, https://links.lww.com/AA/D197.

Study Selection and Data Extraction

Two reviewers (T.M. and A.A.A.) independently screened all selected abstracts that were collected in an EndNote library to determine eligible studies for full-text screening. Studies were included in this systematic review if any of the primary or secondary outcomes were reported by the studies and the criteria of our review met. A standardized Excel spreadsheet was used independently by 2 reviewers (T.M. and A.A.A.) for data extraction on study characteristics, study quality, and our a priori–defined outcomes. Any disagreements during the screening or data extraction phase between the reviewers were resolved through discussion with a senior author (G.W.W.).

Assessment of Study Quality

Two reviewers (T.M. and A.A.A.) independently assessed the study quality using the Newcastle-Ottawa Scale (NOS) for cohort studies.18 The NOS checklist includes the following key items: (1) identification and appropriate selection of the study population; (2) ascertainment and assessment of the outcomes; (3) adequate and appropriate length of follow-up (if applicable); and (4) identifying important confounders and adjusting for them in the appropriate statistical analysis. Items were evaluated using 1 star (⋆) for the selection and outcome categories, while a maximum of 2 stars (⋆ ⋆) could be allocated for the comparability category. If a key point was not mentioned or was unclear in the study, a dash symbol (―) was appointed. A total score for each study was calculated based on the number of stars. The detailed questions checklist used for study quality assessment can be accessed through the following website (http://www.ohri.ca/programs/clinical_epidemiology/oxford.asp).

Statistical Analysis

Meta-analysis was performed to identify differences in mortality rates, pneumonia rates, duration of ICU LOS, and mechanical ventilation in patients with acute traumatic SCI requiring an early or late tracheostomy. We were unable to assess hospital costs and posttracheostomy complications due to lack of available data. The random-effects model by DerSimonian and Laird was used to calculate the pooled effect sizes using the “meta” package in R software (The R Foundation for Statistical Computing 2019, Vienna, Austria).19,20 For pooled dichotomous effect measures (ie, mortality and pneumonia), odds ratio (OR) with 95% confidence interval (CI) was calculated. For pooled continuous effect measures (ie, ICU LOS and mechanical ventilation), mean differences (MDs) were calculated. Finally, a 2-sample t test was calculated to determine if early and late tracheostomy populations had equal mean age. A P value of <.05 was considered statistically significant.

Heterogeneity between studies was quantified and assessed using I2 statistics proposed by Higgins and Thompson.21 In sensitivity analyses, heterogeneity was explored by excluding individual studies and estimating the contribution of studies toward heterogeneity. A P value <.10 or an I2 >35% was considered significant for heterogeneity.21 Furthermore, prediction intervals (PIs) were calculated to quantify the dispersion of effect estimates.22

We performed a subgroup analysis of studies with patients undergoing early tracheostomy exclusively within ≤7 days to assess whether differences in tracheostomy timing among included studies contributed to our outcomes. Additionally, we conducted a subgroup analysis after excluding 2 studies for which only the conference abstracts were available.7,10 Finally, a stratified analysis calculated the OR of an early tracheostomy for (1) level of spinal injury, C1–C5 versus C6–C8, and (2) cervical versus thoracic spinal injuries.

RESULTS

Search Results

F1
Figure 1.:
Flow diagram of included studies.

We identified 3981 records from the electronic database searches. Of the 36 studies reviewed for full-text screening, 28 were excluded for the following reasons: lack of patients with SCI, early versus late tracheostomy not assessed, review articles, and a population with concomitant brain injury. Eight articles met the inclusion criteria and were included in our review (Figure 1).

Characteristics of Selected Studies

Table 1 summaries the characteristics of our included studies. All 8 studies were retrospective cohorts and were conducted in 4 different countries (the United States, Korea, Spain, and Oman).3–10 Two of the 8 studies were conference abstracts.7,10 All studies had patients with acute traumatic cervical SCI, whereas 2 studies had both cervical and thoracic SCI.6,8 Only 4 studies reported on concomitant injuries, which included thoracic and ligamentous injuries.3,5,6,10 The majority of studies characterized early tracheostomy as ≤7 days,3,5,7–10 although 1 study was ≤6 days6 and in another it was ≤10 days.4 Four studies reported on the type of tracheostomy performed, wherein 26,8 utilized both percutaneous and surgical tracheostomy procedure techniques, while the other 2 studies performed either surgical4 or percutaneous9 tracheostomy on their patients.

Table 1. - Characteristics of the Studies Included in the Final Review
Variables Group Beom and Seo,3 2018 Childs et al,10 2015 Choi et al,4 2013 Flanagan et al,5 2017 Ganuza et al,6 2011 Guirgis et al,9 2016 Khan et al,7 2019 Romero et al,8 2009
Study design RC RC RC RC RC RC RC RC
Country of study Korea The United States Korea The United States Spain Oman The United States Spain
Trauma center/hospital Chonnam University Hospital Level 1 NR Level 1 National Hospital of Paraplegics Khoula Hospital Multiple (TQIP database) National Hospital of Paraplegics
Tracheostomy timing ET ≤ 7 d, LT > 7 d ET ≤ 7 d, LT > 7 d ET ≤ 10 d, LT > 10 d ET ≤ 7 d, LT > 7 d ET < 7 d, LT ≥ 7 d ET ≤ 7 d, LT > 7 d ET ≤ 7 d, LT > 7 d ET ≤ 7 d, LT > 7 d
Age, y (mean ± SD) ET 51.2 NR 54.4 ± 14.1 52.1 39.2 ± 8.9 32.2 ± 8.1 NR 38.06 ± 1.87
LT 58.9 NR 45.6 ± 16.5 48.8 43.7 ± 9.2 35.9 ± 8.1 NR 43.66 ± 1.85
Gender, % males ET 80 NR 90 NR 80 78 NR 80
LT 92 NR 91 NR 80 78 NR 80
Spine injury cause (%) ET NR NR NR Fall (51.4), MVA (32.9), MCC (1.4), other (14.3) Fall (33), MVA (60), blunt trauma (5.1), gunshot (0.5), other (1.4) NR NR Fall (28), MVA (64), external trauma (5.3), gunshot (1.3), others (1.3)
LT
Spine injury level (%) ET C4 NR C1/C2 (10), C3–C5 (70), C6/C7 (20) C1–C4 (84); ≥C5 (16) Cervical (86.1), thoracic (13.9) C1/C2 (63), C3–C7 (37) NR C3–C5 (59), C6–C8 (27), T1–T5 (13), T6–T12 (1.4)
LT C4 (33) NR C1/C2 (0), C3–C5 (81.8), C6/C7 (18.2) C1–C4 (55), ≥C5 (45) Cervical (74.6), thoracic (25.4) C1/C2 (72), C3–C7 (28) NR C3–C5 (46), C6–C8 (28.4), T1–T5 (16), T6–T12 (9.9)
ASIA Injury Scale (%) ET Mean 7.7 NR A (20), B (20), C (60), D (0) Mean 3.7 A/B (83.2), C/D (16.8) NR NR A (77.5), B (5.6), C (15.5), D (1.4)
LT Mean 19.5 NR A (54.5), B (9.1), C (27.3), D (9.1) Mean 3.2 A/B (91.2), C/D (8.8) NR NR A (79), B (12.3), C (8.6), D (0)
Associated injuries (%) ET Thoracic (18.2) Ligaments (53.3) NR Chest (31.4) Not specified (43.7) NR NR NR
LT
ISS (mean ± SD) ET NR NR NR Mean 19.5 NR Severe: 66.7% NR 28.47 ± 0.87
LT NR NR NR Mean 19.7 NR Severe: 55.6% NR 29.99 ± 0.80
Tracheostomy type ET NR NR Surgical NR Surgical and percutaneous Percutaneous NR Surgical and percutaneous
LT
Abbreviations: ASIA, American Spinal Injury Association; ET, early tracheostomy; ISS, Injury Severity Scale; LT, late tracheostomy; MCCs, motorcycle crashes; MVA, motor vehicle accident; NR, not reported; RC, retrospective cohort; SD, standard deviation; TQIP, trauma quality improvement program.

The total number of patients with acute traumatic SCI among our 8 included studies was 1220, of whom 441 had an early tracheostomy and 779 underwent late tracheostomy. The mean age of patients in early (44.5 years; 95% CI, 34.9–54.2 years) and late (46.1 years; 95% CI, 38.1–54.0 years) tracheostomy groups was similar. Furthermore, men constituted 80% of patients in the early and late tracheostomy groups among studies that reported on the proportion of gender within their study population.

Primary and Secondary Outcomes

Table 2. - The Reported Outcomes in Included Studies Grouped by Early and Late Tracheostomy
Author Groups Total sample, n In-hospital Mortality, n (%) Pneumonia, n (%) Total ICU Length of Stay, d (Mean ± SD) Total Duration of Mechanical Ventilation, d (Mean ± SD)
Beom and Seo,3 2018 ET 10 NR NR 11.4 6.0
LT 12 19.7 6.9
Childs et al,10 2015 ET 27 2 (7.4) NR 23.0 42.3
LT 35 4 (11.4) 25.7 49.2
Choi et al,4 2013 ET 10 NR 4 (40) 20.8 ± 6.0 5.0 ± 6.5
LT 11 9 (82) 38.0 ± 18.5 29.2 ± 22.9
Flanagan et al,5 2017 ET 37 1 (2.7) 14 (37.8) 20.7 ± 6.5 23.9 ± 16.5
LT 33 1 (3.0) 15 (45.5) 26.0 ± 11.4 36.9 ± 26.7
Ganuza et al,6 2011 ET 101 1 (1.0) 75 (74.2) 36.5 ± 21.6 26.1 ± 11.7
LT 114 4 (3.5) 83 (72.8) 54.6 ± 24.9 48.8 ± 13.5
Guirgis et al,9 2016 ET 51 5 (9.8) NR 21.3 ± 30.8 10.7 ± 8.8
LT 18 6 (33.3) 25.9 ± 18.5 19.5 ± 10.5
Khan et al,7 2019 ET 134 8 (6.0) NR NR NR
LT 475 30 (6.3)
Romero et al,8 2009 ET 71 1 (1.4) 62 (87.3) 36.52 ± 1.59 26.07 ± 1.69
LT 81 5 (6.2) 76 (93.8) 54.58 ± 2.9 48.75 ± 3.4
Abbreviations: ET, early tracheostomy; ICU, intensive care unit; LT, late tracheostomy; NR, not reported; SD, standard deviation.

Table 3. - Outcomes and Heterogeneity Assessment From the Main Meta-analysis Comparing Early Versus Late Tracheostomy in SCI Patients
Outcomes No. of Studies Effect Size (OR or MD) 95% Confidence Interval 95% Prediction Interval I 2
Mortality 6 0.56 0.32 to 1.01 0.25 to 1.29 0.0%
Pneumonia 4 0.66 0.34 to 1.29 0.06 to 6.94 35.6%
ICU length of stay, d 5 −13.09 −19.18 to −7.00 −34.39 to +8.20 88.8%
Mechanical ventilation, d 5 −18.30 −24.33 to −12.28 −39.48 to +2.87 85.6%
Abbreviations: ICU, intensive care unit; MD, mean difference; OR, odds ratio; SCI, spinal cord injury.

F2
Figure 2.:
Forest plot of studies measuring the OR, using the fixed- and random-effects model, of (A) mortality and (B) pneumonia between early and late tracheostomy groups in patients with traumatic spinal cord injuries. The computed weighted ORs are depicted as diamonds proportional to the size of the study. The bars depict the 95% CIs. Studies favoring the early tracheostomy group are on the left-hand side of the center line of no effect, while studies against the early tracheostomy group are on the right-hand side of the center line of no effect. CI indicates confidence interval; ET, early tracheostomy; LT, late tracheostomy; OR, odds ratio.
F3
Figure 3.:
Forest plot of studies measuring the MD, using the fixed- and random-effects model, of (A) ICU LOS and (B) MV duration between early and late tracheostomy groups in patients with traumatic spinal cord injuries. The computed weighted MDs are depicted as diamonds proportional to the size of the study. The bars depict the 95% CIs. Studies favoring the early tracheostomy group are on the left-hand side of the center line of no effect, while studies against the early tracheostomy group are on the right-hand side of the center line of no effect. CI indicates confidence interval; ET, early tracheostomy; ICU, intensive care unit; LOS, length of stay; LT, late tracheostomy; MD, mean difference; MV, mechanical ventilation.

Table 2 lists the extracted data of our outcomes from included studies. Six studies reported on in-hospital mortality.5–10 Although mortality rates were lower among patients in the early tracheostomy group compared to the late tracheostomy population, the results were not significant (OR = 0.56; 95% CI, 0.32–1.01; P = .054; I2 = 0%; Figure 2A). Out of the 7 studies that reported on ICU LOS and duration of mechanical ventilation, 54–6,8,9 were used to calculate the MD due to incomplete data (ie, lack in standard deviation data) in 2 studies.3,10 Early tracheostomy was associated with reduced mean ICU LOS by 13 days (95% CI, −19.18 to −7.00; P = .001; I2 = 88.8%; Figure 3A) and mean duration of mechanical ventilation by 18.30 days (95% CI, −23.33 to −12.28; P = .001; I2 = 85.6%; Figure 3B). Four studies reported on pneumonia rates.4–6,8 There were no significant differences in total pneumonia rates between the early and late tracheostomy groups (OR = 0.66; 95% CI, 0.34–1.29; P = .226; I2 = 35.6%; Figure 2B). Finally, none of the studies reported on hospital costs, and a paucity of data was available on posttracheostomy complications, hence, a meta-analysis was not feasible. Table 3 summarizes the effect measures with 95% CI and PI of our outcomes.

Subgroup Analysis

The first subgroup analysis excluded 2 of the 8 studies in our review with patients who underwent tracheostomy outside of the specified cutoff time frame (early tracheostomy ≤7 days and late tracheostomy ≥8 days).4,6 There were no significant differences in the risk of in-hospital mortality (OR = 0.58; 95% CI, 0.30–1.10; P = .093) and pneumonia (OR = 0.60; 95% CI, 0.29–1.25; P = .172) between early and late tracheostomy groups. Although slightly attenuated, the mean duration of mechanical ventilation remained significantly reduced in the early tracheostomy group (MD = 15 days; 95% CI, −24.0 to −6.90; P = .0004). The mean ICU LOS was 3 days shorter compared to our main meta-analysis findings but still significantly lower in the early tracheostomy group (MD = 10 days; 95% CI, −19.13 to −1.41; P = .023).

The second subgroup analysis excluded the 2 conference abstracts. Compared to patients who underwent late tracheostomy, the risk of in-hospital mortality was significantly lower in the early tracheostomy group (OR = 0.27; 95% CI, 0.10–0.69; P = .006; Supplemental Digital Content 3, File 2, https://links.lww.com/AA/D198). Compared to our main meta-analysis findings, the effect measures of risk of pneumonia, mean ICU LOS, and duration of mechanical ventilation were similar.

Stratified Analysis

Stratified analysis of 2 studies demonstrated that patients with cervical SCI were twice as likely to undergo early tracheostomy compared to thoracic SCI (OR = 2.13; 95% CI, 1.24–3.64; P = .006; I2 = 0%).6,8 Moreover, we found that, although patients with a higher cervical SCI (C1–C5 versus C6–C8) were more likely to undergo early tracheostomy, the results were not significant (OR = 1.63; 95% CI, 0.88–3.03; P = .119; I2 = 0%).4,8

Quality of Studies

The quality of included studies is presented in Supplemental Digital Content 4, Table S2, https://links.lww.com/AA/D199. Most studies rated fair on the selection domain of NOS, wherein 2 studies4,5 rated good. The exposed cohort (ie, traumatic SCI) was representative of the study population and properly ascertained (ie, medical records) among all studies, although demonstration of outcome of interest before start of study was not always stated. Only 1 study5 stated that they controlled for multiple confounding factors in their analysis that may lead to early tracheostomy, while 5 studies3,4,6,8,9 matched the patient characteristic in the early and late tracheostomy groups in the study design. The remaining 2 studies7,10 were conference abstracts, and information on comparability of cohorts on the basis of design and analysis was not stated in the abstract. Finally, all studies were rated good in the outcome domain of NOS.

Heterogeneity Assessment

There was significant clinical heterogeneity present among the included studies due to variable assessments of the duration of mechanical ventilation, ICU LOS, and pneumonia. Differences in population characteristic, such as level of spinal injury, timing of tracheostomy, and concomitant trauma-based injuries, could have also influenced the pooled analysis.

No significant statistical heterogeneity was present for mortality risk assessment (I2 = 0%). More importantly, the predicted treatment effect for risk of mortality with early tracheostomy (versus late tracheostomy) in patients with SCI was between 0.25 and 1.26, illustrating that future studies may or may not show a decreased risk of mortality with an early tracheostomy. Similarly, the 95% PI for ICU LOS (I2 = 88.8%) and mechanical ventilation (I2 = 85.6%) indicates that an early tracheostomy may not lead to significantly shorter duration of ICU stay or mechanical ventilation in future studies. However, the PI for these outcomes also contains largely negative value that suggests that future studies with SCI patients who undergo an early tracheostomy could have very large effects in decreasing the ICU LOS and duration of mechanical ventilation.

On omitting 1 study9 from the pooled estimate for duration of mechanical ventilation in a sensitivity analysis, the statistical heterogeneity decreased from 85.6% to 8.1%. The mean duration difference of mechanical ventilation increased slightly without affecting the final inference of our results (22.54 days; 95% CI, −23.86 to −21.22; P = .0001; I2 = 8.1%).

DISCUSSION

Summary of Main Results

To our knowledge, this study is the first systematic review and meta-analysis to assess whether differences in various outcomes exist between early and late tracheostomy in patients with acute SCI. In total, we included 8 studies in our meta-analysis. Compared to late tracheostomy, early tracheostomy was associated with lower mean ICU LOS and mean duration of mechanical ventilation. After excluding the conference abstracts, we noted a significantly lower risk of in-hospital mortality in the early tracheostomy group. No differences in the risk of pneumonia were noted between early and late tracheostomy timing. Our findings suggest that, in patients with SCI, specifically those with cervical injuries, early tracheostomy may be beneficial in weaning patients off mechanical ventilation faster and in turn prompting a quicker ICU discharge or transfer to an acute care facility.

ICU LOS and Mechanical Ventilation

Tracheostomy makes breathing more comfortable and efficient for patients with SCI by decreasing the work of breathing and dead-space ventilation, improving pulmonary hygiene, reducing airway resistance, and facilitating faster weaning from mechanical ventilation, thereby reducing the duration of mechanical ventilation and possibly ICU LOS.6,23 Patients who undergo an early tracheostomy are more likely to have had a higher neurological level of injury (ie, upper cervical SCI, and/or a severe score on the American Spinal Injury Association [ASIA] Impairment Scale) and are more likely to require prolonged mechanical ventilation prompting clinicians to perform an early tracheostomy.24 On the contrary, patients with lower-level spinal injuries may have a possible lag time between presentation of respiratory symptoms and time of injury due to gradually progressive ascending spinal edema that may require ongoing ventilatory support and, ultimately, tracheostomy.2 A lower motor weakness on the ASIA scale, a higher level of spinal injury, and the presence of paradoxical respiration have been shown to be predictors of tracheostomy, although the ideal tracheostomy timing is likely dependent on the physician judgment and patient’s initial clinical presentation.3,24 Nevertheless, our results (main and subanalysis) suggest that patients who undergo early tracheostomy may have a shorter duration of total mechanical ventilation and ICU LOS, which has been noted in the general critical care population.25,26

Mortality

Several meta-analyses have reported that critically ill patients who undergo an early or late tracheostomy have no significant differences in the risk of short-term or long-term mortality.26–29 On the contrary, 3 meta-analyses have shown lower long-term mortality rates with earlier tracheostomy.14,25,30 Long-term outcomes of patients with SCI are closely associated with the level of spinal injury, the severity of primary injury, and the progression of secondary injuries.2 Hence, difficulties can arise when assessing long-term mortality risk in early and late tracheostomy groups due to vast differences in patients’ primary and secondary injuries. Furthermore, small study sample sizes and a lack of uniform measurement of mortality at discharge or at other time points across studies can produce unreliable results that should be interpreted with caution. Although we did not assess long-term mortality, the pooled risk of in-hospital mortality was statistically significantly lower in the early tracheostomy group, after excluding the conference abstracts, compared to late tracheostomy. Studies specifically looking at patients with severe head injuries have demonstrated that early tracheostomy may result in lower mortality31–33 or there may be no difference34,35 in mortality between early and late tracheostomy. Based on our results, it is difficult to draw conclusions on the observed lower mortality benefits with early tracheostomy. The need for high-quality trials is essential to assess this.

SCI Pathophysiology

Injuries to the cervical and thoracic spinal cord put SCI patients at an increased risk of respiratory failure due to disruption of spinal nerves that innervate respiratory muscles.36 The severity of respiratory impairments correlates with increasingly higher spinal injuries.37,38 The diaphragm, which is innervated by the phrenic nerve (C3–C5), and the accessory muscles used for inspiration are commonly damaged in traumatic cervical injuries. The inspiratory capacity, which is the maximum volume of air that can be inspired after reaching the end of a normal quiet expiration, is decreased, contributing to atelectasis, dyspnea on exertion, and, in more severe cases, respiratory insufficiency.36 Moreover, damage to the thoracic and lumbar nerve roots impact the abdominal and the internal intercostal muscles of expiration.36 These muscles are crucial when forced exhalation is needed, such as during exercise or coughing.39 When the ability to generate forced exhalation for coughing is impaired, removal of airway secretions is ineffective, and the resulting accumulation of secretions can cause airway obstruction and increase susceptibility to lower respiratory tract infections.39 Finally, SCI can lead to a loss of postganglionic sympathetic innervation to the airways that may lead to an asthma-like disorder of airway function.40 This abnormality is thought to be due to the unopposed effects of parasympathetic innervation (vagal-cholinergic) on respiratory smooth muscle resulting from disruption of the sympathetic efferent fibers.40

Limitations

Our review has several limitations. Most of the studies included had a small sample size and did not always report on all outcomes. Two of the 8 studies were conference abstracts with sparse data to assess all outcomes and overall bias of these studies. Moreover, the studies had differing characteristics of trauma centers, mechanism and associated SCI, type of tracheostomy procedure performed, level and severity of spinal injury, and inconsistent definitions of early versus late tracheostomy cutoff timing (7 vs 10 days). Due to insufficient and missing data on several important patient characteristics that may impact tracheostomy timing, we were unable to explore these patient-level confounders in depth. Due to missing or incomplete information on procedural-related complications and recent spine stabilization surgery, we were unable to assess whether this affected our outcomes among early and late tracheostomy groups. There was also some variability among studies in measuring the primary and secondary outcomes using standardized guidelines. Finally, there could be a potential publication bias as only English language articles were included in our study.

The overall low quality due to clinical and methodological heterogeneities between studies and the lack of available data on patient characteristics that result in an early or late tracheostomy indication highlight the need for further higher-quality prospective studies. Future trials must not only find the optimal tracheostomy timing but also answer why and in whom an early tracheostomy should be performed. Due to the aforementioned limitations of this review and included studies, we are unable to answer these vital questions.

CONCLUSIONS

Based on the available data, our review suggests that an early tracheostomy within the first 7 days of injury or tracheal intubation in patients with SCI may be associated with a lower risk of in-hospital mortality and may reduce ICU LOS and the duration of mechanical ventilation. Overall, caution should be exercised in the interpretation of these findings due to the low quality of included studies. Future prospective trials with a larger patient population are needed, as knowledge on who should get an early tracheostomy and the potential short- and long-term benefits of an early tracheostomy will help physicians make clinical decisions.

ACKNOWLEDGMENTS

This work was conducted at the Department of Anesthesiology, McGovern Medical School, University of Texas Health Science Center at Houston (UT Health), Houston, TX.

DISCLOSURES

Name: Talha Mubashir, MD.

Contribution: This author helped design the study, collect the data, perform the data analysis, interpret the data, and write the manuscript.

Name: Abdul A. Arif, BSc.

Contribution: This author helped collect the data and prepare the manuscript.

Name: Prince Ernest, MD.

Contribution: This author helped prepare the manuscript and interpret the data.

Name: Vahed Maroufy, PhD.

Contribution: This author helped perform the data analysis, prepare the manuscript, and interpret the data.

Name: Rabail Chaudhry, MD.

Contribution: This author helped prepare the manuscript and interpret the data.

Name: Julius Balogh, MD.

Contribution: This author helped prepare the manuscript and interpret the data.

Name: Colin Suen, MD, PhD.

Contribution: This author helped prepare the manuscript and interpret the data.

Name: Alexander Reskallah, MD.

Contribution: This author helped prepare the manuscript and interpret the data.

Name: George W. Williams, MD.

Contribution: This author helped design the study, interpret the data, and write the manuscript.

This manuscript was handled by: Richard P. Dutton, MD.

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