Clinical evaluation and airway management for adults with cervical spine instability

[Anesthesia in spinal surgery]

Over the past 20 years improvements in surgical techniques and perioperative patient care have led to a considerable increase in surgical procedures of the spine worldwide. Therefore, the spectrum was extended from minimally invasive procedures up to complex operations over several segments of the spinal column with high loss of blood and complex perioperative management. This article presents the principal pillars of preoperative, intraoperative and postoperative management relating to spinal surgery. Furthermore, procedure-specific features, such as airway management in cervical spine instability or implementation of intraoperative neuromonitoring are dealt with in detail.

Intubation biomechanics: Computational modeling to identify methods to minimize cervical spine motion and spinal cord strain during laryngoscopy and tracheal intubation in an intact cervical spine

STUDY OBJECTIVE

To minimize the risk of cervical spinal cord injury in patients who have cervical spine pathology, minimizing cervical spine motion during laryngoscopy and tracheal intubation is commonly recommended. However, clinicians may better aim to reduce cervical spinal cord strain during airway management of their patients. The aim of this study was to predict laryngoscope force characteristics (location, magnitude, and direction) that would minimize cervical spine motions and cord strains.

DESIGN

We utilized a computational model of the adult human cervical spine and spinal cord to predict intervertebral motions (rotation [flexion/extension] and translation [subluxation]) and cord strains (stretch and compression) during laryngoscopy.

INTERVENTIONS

Routine direct (Macintosh) laryngoscopy conditions were defined by a specific force application location (mid-C3 vertebral body), magnitude (48.8 N), and direction (70 degrees). Sixty laryngoscope force conditions were simulated using 4 force locations (cephalad and caudad of routine), 5 magnitudes (25-200% of routine), and 3 directions (50, 70, 90 degrees).

MAIN RESULTS

Under all conditions, extension at Oc-C1 and C1-C2 were greater than in all other cervical segments. Decreasing force magnitude to values reported for indirect laryngoscopes (8-17 N) decreased cervical extension to ~50% of routine values. The cervical cord was most likely to experience potentially injurious compressive strain at C3, but force magnitudes ≤50% of routine (≤24.4 N) decreased strain in C3 and all other cord regions to non-injurious values. Changing laryngoscope force locations and directions had minor effects on motion and strain.

CONCLUSIONS

The model predicts clinicians can most effectively minimize cervical spine motion and cord strain during laryngoscopy by decreasing laryngoscope force magnitude. Very low force magnitudes (<5 N, ~10% of routine) are necessary to decrease overall cervical extension to <50% of routine values. Force magnitudes ≤24.4 N (≤50% of routine) are predicted to help prevent potentially injurious compressive cord strain.

Is there a relationship between sagittal cervical spine mobility and generalised joint hypermobility? A cross-sectional study of 1000 healthy Australians

OBJECTIVES

The primary aim was to determine the association between sagittal cervical mobility and the presence and extent of GJH across the lifespan. Secondary aims were to determine which features explain variability in cervical range of motion (CROM) and to establish the sagittal cervical hypermobile range in both genders across the lifespan.

DESIGN

Cross-sectional observational study. Spearman's rho determined the relationship between presence and extent of GJH and CROM, age, gender and ethnicity. Multiple regression identified the factors explaining variability in CROM. The hypermobile CROM was identified as the upper 5% of flexion, extension and combined ranges for age and gender.

SETTING

University laboratory in Sydney Australia.

PARTICIPANTS

One thousand healthy individuals, aged 3-101 years.

OUTCOME MEASURES

Cervical active range of motion was assessed using an inclinometer, extent of and presence of generalised joint hypermobility were assessed using the Beighton scoring system and age- and gender-specific criteria respectively.

RESULTS

CROM correlated positively with GJH (Beighton score as a continuous or dichotomous age and gender specific variable) (rho=0.12-0.50; p < 0.001) and negatively with age (rho=0.54; p < 0.001). Age, gender and extent of GJH (Beighton as a continuous score) accounted for 19 to 51% of variability in CROM. Cut-offs for cervical hypermobility were calculated across the lifespan.

CONCLUSIONS

Increased sagittal CROM was observed in individuals identified with GJH. Extension CROM decreased with age more than flexion; the greatest loss in the second and third decades. CROM screening is warranted for patients identified with GJH and for rehabilitation goal-setting.

Two head positions for orotracheal intubation with the trachway videolight intubating stylet with manual in-line stabilization: A randomized controlled trial

BACKGROUND

The Trachway Videolight Intubating Stylet is a video-assisted system with a rigid but malleable intubating stylet that facilitates endotracheal intubation. Minimizing cervical spine movement with manual in-line stabilization is essential for patients with cervical spine injuries such as multiple trauma. However, the intubation time of the Trachway Videolight Intubating Stylet and complications associated with intubation in patients with manual in-line stabilization in the neutral-head and head-lift positions remain unclear.

METHODS

Patients (20-80 years old) who were scheduled to undergo surgery that required general anesthesia with tracheal intubation were randomly allocated to either a neutral-head (n = 62) or a head-lift position (n = 62) group. Manual in-line stabilization was performed to limit cervical spine mobility. We aimed to evaluate orotracheal intubation time and success rate in these 2 positions with the Trachway Videolight Intubating Stylet.

RESULTS

Intubation was faster in the head-lift than in the neutral-head position (20 ± 10 and 25 ± 13 seconds, respectively, P = .000); intubation was equally successful in the 2 positions (96.8% vs 96.8%). Responses to intubation did not differ between positions (heart rate, P = .142; visual analog scale scores for throat soreness, P = .54). The only significant predictor of intubation time was the body mass index in the head-lift position group (P = .005).

CONCLUSIONS

Intubation using the Trachway Videolight Intubating Stylet with manual in-line stabilization is faster in the head-lift position, and therefore preferable. However, if the head-lift position is not suitable, the neutral-head position is a sensible alternative, with comparable intubation success rate, heart rate change, and postoperative throat soreness.

Tracheal intubation in patients at risk for cervical spinal cord injury: A systematic review

BACKGROUND

Tracheal intubation in patients at risk for secondary spinal cord injury is potentially difficult and risky.

OBJECTIVES

To compare tracheal intubation techniques in adult patients at risk for secondary cervical spinal cord injury undergoing surgery. Primary outcome was first-attempt failure rate. Secondary outcomes were time to successful intubation and procedure complications.

DESIGN

Systematic review and meta-analysis of randomized controlled trials (RCTs) with trial sequential analysis (TSA).

DATA SOURCES

Databases searched up to July 2019.

ELIGIBILITY

Randomized controlled trials comparing different intubation techniques.

RESULTS

We included 18 trials enrolling 1972 patients. Four studies used the "awake" approach, but no study compared awake versus non-awake techniques. In remaining 14 RCTs, intubation was performed under general anesthesia. First-attempt failure rate was similar when comparing direct laryngoscopy or fiberoptic bronchoscopy versus other techniques. A better first-attempt failure rate was found with videolaryngoscopy and when pooling all the fiberoptic techniques together. All these results appeared not significant at TSA, suggesting inconclusive evidence. Intubating lighted stylet allowed faster intubation. Postoperative neurological complications were 0.34% (no significant difference among techniques). No life-threatening adverse event was reported; mild local complications were common (19.5%). The certainty of evidence was low to very low mainly due to high imprecision and indirectness.

CONCLUSIONS

Videolaryngoscopy and fiberoptic-assisted techniques might be associated with higher first-attempt failure rate over controls. However, low to very low certainty of evidence does not allow firm conclusions on the best tracheal intubation in patients at risk for cervical spinal cord injury.

Trauma Airway Management: Induction Agents, Rapid Versus Slower Sequence Intubations, and Special Considerations

Trauma patients who require intubation are at higher risk for aspiration, agitation/combativeness, distorted anatomy, hemodynamic instability, an unstable cervical spine, and complicated injuries. Although rapid-sequence intubation is the most common technique in trauma, slow-sequence intubation may reduce the risk for failed intubation and cardiovascular collapse. Providers often choose plans with which they are most comfortable. However, developing a flexible team-based approach, through recognition of complicating factors in trauma patients, improves airway management success.

Airway management in the presence of cervical spine instability: A cross-sectional survey of the members of the Indian Society of Neuroanaesthesiology and Critical Care

BACKGROUND AND AIMS

There is a paucity of clinical practice guidelines for the ideal approach to airway management in patients with cervical spine instability (CSI). The aim of this survey was to evaluate preferences, perceptions and practices regarding airway management in patients with CSI among neuroanaesthesiologists practicing in India.

METHODS

A 25-item questionnaire was circulated for cross-sectional survey to 378 members of the Indian Society of Neuroanaesthesiology and Critical Care (ISNACC) by E-mail. We sent four reminders and again submitted our survey to non-responders during the 2017 annual ISNACC meeting. Apart from demographic information, the survey captured preferred methods of intubation and airway management for patients with CSI and their justification. Regression analysis was used to identify factors associated with the use of indirect technique for intubation.

RESULTS

Only 122 out of the 378 anaesthesiologists responded to our survey. Most respondents were senior consultants, working in training hospitals, and performed ≥25 intubations per year for CSI patients. The majority of neuroanaesthesiologists (78.7%; n = 96) preferred indirect techniques for elective intubation. However, 45 anaesthesiologists (36.9%) preferred indirect techniques for emergency intubation. In an adjusted analysis, preference for patients to be conscious during intubation was significantly associated with the use of indirect techniques (odds ratio = 3.79; confidence interval = 1.52-9.49, P < 0.01).

CONCLUSIONS

Among ISNACC members, indirect techniques are preferred for elective intubation of patients with CSI, while direct laryngoscopy is preferred for emergency intubation.