Comparison of 4 airway devices on cervical spine alignment in a cadaver model with global ligamentous instability at C5-C6

Direct versus indirect epiglottis elevation in cervical spine movement during videolaryngoscopic intubation under manual in-line stabilization: a randomized controlled trial

BACKGROUND

During videolaryngoscopic intubation, direct epiglottis elevation provides a higher percentage of glottic opening score than indirect epiglottis elevation. In this randomized controlled trial, we compared cervical spine movement during videolaryngoscopic intubation under manual in-line stabilization between the two glottis exposure methods.

METHODS

Videolaryngoscopic intubation under manual in-line stabilization was performed using C-MAC® D-blade: direct (n = 51) and indirect (n = 51) epiglottis elevation groups. The percentage of glottic opening score was set equally at 50% during videolaryngoscopic intubation in both groups. The primary outcome measure was cervical spine movement during videolaryngoscopic intubation at the occiput-C1, C1-C2, and C2-C5. The secondary outcome measures included intubation performance (intubation success rate and intubation time).

RESULTS

Cervical spine movement during videolaryngoscopic intubation was significantly smaller at the occiput-C1 in the direct epiglottis elevation group than in the indirect epiglottis elevation group (mean [standard deviation] 3.9 [4.0] vs. 5.8 [3.4] °, P = 0.011), whereas it was not significantly different at the C1-C2 and C2-C5 between the two groups. All intubations were successful on the first attempt, achieving a percentage of glottic opening score of 50% in both groups. Intubation time was longer in the direct epiglottis elevation group (median [interquartile range] 29.0 [24.0-35.0] vs. 22.0 [18.0-27.0] s, P < 0.001).

CONCLUSIONS

When performing videolaryngoscopic intubation under manual in-line stabilization, direct epiglottis elevation can be more beneficial than indirect epiglottis elevation in reducing cervical spine movement during videolaryngoscopic intubation at the occiput-C1.

TRIAL REGISTRATION

Clinical Research Information Service (number: KCT0006239, date: 10/06/2021).

Effects of External Laryngeal Manipulation on Cervical Spine Motion during Videolaryngoscopic Intubation under Manual In-Line Stabilization: A Randomized Crossover Trial

We hypothesized that external laryngeal manipulation would reduce cervical spine motion during video laryngoscopic intubation under manual in-line stabilization by reducing the force required to lift the videolaryngoscope. In this randomized crossover trial, 27 neurointerventional patients underwent two consecutive videolaryngoscopic intubation attempts under manual in-line stabilization. External laryngeal manipulation was applied to all patients in either the first or second attempt. In the second attempt, we tried to reproduce the percentage of glottic opening score obtained in the first attempt. Primary outcomes were cervical spine motion during intubation at the occiput-C1, C1–C2, and C2–C5 segments. The intubation success rate (secondary outcome measure) was recorded. Cervical spine motion during intubation at the occiput-C1 segment was significantly smaller with than without external laryngeal manipulation (7.4° ± 4.6° vs. 11.5° ± 4.8°, mean difference −4.1° (98.33% confidence interval −5.8° to −2.3°), p < 0.001), showing a reduction of 35.7%. Cervical spine motion during intubation at the other segments was not significantly different with versus without external laryngeal manipulation. All intubations were achieved successfully regardless of the application of external laryngeal manipulation. External laryngeal manipulation is a useful method to reduce upper cervical spine motion during videolaryngoscopic intubation under manual in-line stabilization.

Randomized crossover trial comparing cervical spine motion during tracheal intubation with a Macintosh laryngoscope versus a C-MAC D-blade videolaryngoscope in a simulated immobilized cervical spine

BACKGROUND

Maintaining cervical immobilization is essential during tracheal intubation in patients with unstable cervical spines. When using the Macintosh laryngoscope for intubation in patients with cervical immobilization, substantial neck extension is required for visualization of the glottis. However, the C-MAC D-Blade videolaryngoscope may require less neck extension due to its acute angulation. We hypothesized that C-MAC D-Blade videolaryngoscopic intubation would result in less cervical spine movement than Macintosh laryngoscopic intubation. We compared the effects of C-MAC D-Blade videolaryngoscopic intubation and Macintosh laryngoscopic intubation in terms of cervical spine motion during intubation in patients with simulated cervical immobilization.

METHODS

In this randomized crossover study, the cervical spine angle was measured at the occiput-C1, C1-C2, and C2-C5 segments before and during tracheal intubation with either a C-MAC D-Blade videolaryngoscope or Macintosh laryngoscope in 20 patients, with application of a neck collar for simulated cervical immobilization. Cervical spine motion was defined as the change in angle measured before and during tracheal intubation.

RESULTS

The cervical spine motion at the occiput-C1 segment was measured at 12.1 ± 4.2° and 6.8 ± 5.0° during Macintosh laryngoscopic and C-MAC D-blade videolaryngoscopic intubation, respectively, corresponding to a 44% reduction in cervical spine motion when using the latter device (mean difference, - 5.3; 98.33% CI: - 8.8 to - 1.8; p = 0.001). However, there was no significant difference between the two intubation devices at the C1-C2 segment (- 0.6; 98.33% CI: - 3.4 to 2.2; p = 0.639) or C2-C5 segment (0.2; 98.33% CI: - 6.0 to 6.4; p = 0.929).

CONCLUSIONS

The C-MAC D-Blade videolaryngoscope causes less upper cervical spine motion than the Macintosh laryngoscope during tracheal intubation of patients with simulated cervical immobilization.

TRIAL REGISTRATION

This study was registered at ClinicalTrials.gov on June 26, 2018 ( NCT03567902 ).

Radiographic comparison of cervical spine motion using LMA Fastrach, LMA CTrach, and the Macintosh laryngoscope

Background/aim

The optimal technique for airway management in patients with cervical pathology remains unclear. Intubating laryngeal mask airway devices such as LMA CTrach and LMA Fastrach have not been compared for cervical spine (C-spine) movements in the context of cervical pathology. The present study aimed to determine upper C-spine movements by radiography during intubation with different devices as well as comparing the duration and success of intubation in cervical surgery.

Materials and methods

Sixty patients scheduled for elective cervical surgery were registered in this prospective, randomized study. Patients with cervical trauma/injury, previous neck surgery, and body mass index (BMI) of >35 kg/m² were excluded. Participants were randomized to one of the 3 groups: LMA CTrach, LMA Fastrach, or the Macintosh laryngoscope. C-spine motion was evaluated by measuring angles created by bordering vertebrae at cervical 1/2 and 2/3 (C1/2, C2/3) segments on 2 lateral cervical radiographs for each patient. Intubation time, ease of intubation, number of attempts, and success rate were also documented.

Results

Demographic data were similar in all the groups. The cervical movement with LMA CTrach and LMA Fastrach compared to the Macintosh laryngoscope were similar at C1/2. However, LMA CTrach significantly reduced extension compared to LMA Fastrach and Macintosh laryngoscopes at C2/3. Duration of intubation was significantly shorter with the Macintosh laryngoscope. The rate of successful intubation was 80% with LMA Fastrach and 100% with both LMA CTrach and the Macintosh laryngoscopes.

Conclusion

The LMA CTrach laryngoscopy involves less upper C-spine movement than the LMA Fastrach and does not increase the duration of the intubation period.

Cervical Spine Motion During Tracheal Intubation Using an Optiscope Versus the McGrath Videolaryngoscope in Patients With Simulated Cervical Immobilization: A Prospective Randomized Crossover Study

BACKGROUND

In patients with an unstable cervical spine, maintenance of cervical immobilization during tracheal intubation is important. In McGrath videolaryngoscopic intubation, lifting of the blade to raise the epiglottis is needed to visualize the glottis, but in patients with an unstable cervical spine, this can cause cervical spine movement. By contrast, the Optiscope, a rigid video-stylet, does not require raising of the epiglottis during tracheal intubation. We therefore hypothesized that the Optiscope would produce less cervical spine movement than the McGrath videolaryngoscope during tracheal intubation. The aim of this study was to compare the Optiscope with the McGrath videolaryngoscope with respect to cervical spine motion during intubation in patients with simulated cervical immobilization.

METHODS

The primary outcome of the study was the extent of cervical spine motion at the occiput-C1, C1-C2, and C2-C5 segments. In this randomized crossover study, the cervical spine angle was measured before and during tracheal intubation using either the Optiscope or the McGrath videolaryngoscope in 21 patients with simulated cervical immobilization. Cervical spine motion was defined as the change in angle at each cervical segment during tracheal intubation.

RESULTS

There was significantly less cervical spine motion at the occiput-C1 segment using the Optiscope rather than the McGrath videolaryngoscope (mean [98.33% CI]: 4.7° [2.4-7.0] vs 10.4° [8.1-12.7]; mean difference [98.33% CI]: -5.7° [-7.5 to -3.9]). There were also fewer cervical spinal motions at the C1-C2 and C2-C5 segments using the Optiscope (mean difference versus the McGrath videolaryngoscope [98.33% CI]: -2.4° [-3.7 to -1.2]) and -3.7° [-5.9 to -1.4], respectively).

CONCLUSIONS

The Optiscope produces less cervical spine motion than the McGrath videolaryngoscope during tracheal intubation of patients with simulated cervical immobilization.

Comparison of cervical spine motion during intubation with a C‑MAC D‑Blade® and an LMA Fastrach®

BACKGROUND

This prospective randomized study compared cervical motion during intubation with a C‑MAC D‑Blade® and with a laryngeal mask airway LMA Fastrach®.

MATERIAL AND METHODS

The participants in this study were 52 ASA I-III patients aged 18-70 years and assigned for elective cervical discectomy. The patients were randomly selected for intubation with a C‑MAC D‑Blade® (group V) or an LMA Fastrach® laryngeal airway (group F). Both groups received the same induction of anaesthesia. The first lateral view was X‑rayed while the head and neck were in a neutral supine position and the second exposure was taken during the passage of the endotracheal tube through the vocal cords for group V and during the advance of the endotracheal tube for group F. The occiput-C1 (C0-C1), C1-C2 and C2-5 angles were measured. The angle formed by the line between the occipital protuberance and anterior process of the foramen magnum and the line between the central point of C1 spinous process and the anterior process of the foramen magnum was defined as angle A. The differences between the angles were calculated. Overall intubation success and first-pass success (success at the first attempt) were recorded.

RESULTS

The change in angulations between C0-C1 during intubation was significantly lower in group F than in group V (2.78⁰ ± 2.1⁰ vs. 6.04⁰ ± 4.1⁰, p = 0.007). Before intubation, angle A was 14.4⁰ ± 3.9⁰ in group V and 13.8⁰ ± 3.7⁰ in group F (p = 0.627). During intubation, angle A was significantly smaller for group V than for group F (9.1⁰ ± 2.4⁰ vs. 10.7⁰ ± 2.9⁰, p = 0.04). The number of successful intubations were significantly higher in group V (100% of intubations were successful on the first attempt for group V, vs. 80% for group F, p = 0.023).

CONCLUSION

Intubation with both a C‑MAC D‑Blade and a Fastrach LMA resulted in cervical motion but within safe ranges. Intubation with a C-mac D blade might be preferred because the Fastrach LMA may result in more failed intubation attempts in patients with cervical spine disorders.

Intubation biomechanics: validation of a finite element model of cervical spine motion during endotracheal intubation in intact and injured conditions

OBJECTIVE

Because of limitations inherent to cadaver models of endotracheal intubation, the authors’ group developed a finite element (FE) model of the human cervical spine and spinal cord. Their aims were to 1) compare FE model predictions of intervertebral motion during intubation with intervertebral motion measured in patients with intact cervical spines and in cadavers with spine injuries at C-2 and C3–4 and 2) estimate spinal cord strains during intubation under these conditions.

METHODS

The FE model was designed to replicate the properties of an intact (stable) spine in patients, C-2 injury (Type II odontoid fracture), and a severe C3–4 distractive-flexion injury from prior cadaver studies. The authors recorded the laryngoscope force values from 2 different laryngoscopes (Macintosh, high intubation force; Airtraq, low intubation force) used during the patient and cadaver intubation studies. FE-modeled motion was compared with experimentally measured motion, and corresponding cord strain values were calculated.

RESULTS

FE model predictions of intact intervertebral motions were comparable to motions measured in patients and in cadavers at occiput–C2. In intact subaxial segments, the FE model more closely predicted patient intervertebral motions than did cadavers. With C-2 injury, FE-predicted motions did not differ from cadaver measurements. With C3–4 injury, however, the FE model predicted greater motions than were measured in cadavers. FE model cord strains during intubation were greater for the Macintosh laryngoscope than the Airtraq laryngoscope but were comparable among the 3 conditions (intact, C-2 injury, and C3–4 injury).

CONCLUSIONS

The FE model is comparable to patients and cadaver models in estimating occiput–C2 motion during intubation in both intact and injured conditions. The FE model may be superior to cadavers in predicting motions of subaxial segments in intact and injured conditions.

Comparison of the Vacuum Mattress versus the Spine Board Alone for Immobilization of the Cervical Spine Injured Patient: A Biomechanical Cadaveric Study

STUDY DESIGN

A biomechanical cadaveric study.

OBJECTIVE

We sought to determine the amount of motion generated in an unstable cervical spine fracture with use of the vacuum mattress versus the spine board alone. Our hypothesis is that the vacuum mattress will better immobilize an unstable cervical fracture.

SUMMARY OF BACKGROUND DATA

Trauma patients in the United States are immobilized on a rigid spine board, whereas in many other places, vacuum mattresses are used with the proposed advantages of improved comfort and better immobilization of the spine.

METHODS

Unstable subaxial cervical injuries were surgically created in five fresh whole human cadavers. The amount of motion at the injured motion segment during testing was measured using a Fastrak, three-dimensional, electromagnetic motion analysis device (Polhemus Inc.). The measurements recorded in this investigation included maximum displacements during application and removal of the device, while tilting to 90°, during a bed transfer, and a lift onto a gurney. Linear and angular displacements were compared using the Generalized Linear Model analysis of variance for repeated measures for each of the six dependent variables (three planes of angulations and three axes of displacement).

RESULTS

There was more motion in all six planes of motion during the application process with use of the spine board alone, and this was statistically significant for axial rotation (P = 0.011), axial distraction (P = 0.035), medial-lateral translation (P = 0.027), and anteroposterior translation (P = 0.026). During tilting, there was more motion with just the spine board, but this was only statistically significant for anteroposterior translation (P = 0.033). With lifting onto the gurney, there was more motion with the spine board in all planes with statistical significance, except lateral bending. During the removal process, there was more motion with the spine board alone, and this was statistically significant for axial rotation (P = 0.035), lateral bending (P = 0.044), and axial distraction (P = 0.023).

CONCLUSION

There was more motion when using a spine board alone during typical maneuvers performed during early management of the spine injured patient than the vacuum mattress. There may be benefit of use of the vacuum mattress versus the spine board alone in preventing motion at an unstable, subaxial cervical spine injury.

LEVEL OF EVIDENCE

2.

Intubation biomechanics: laryngoscope force and cervical spine motion during intubation in cadavers—effect of severe distractive-flexion injury on C3–4 motion

OBJECTIVE

With application of the forces of intubation, injured (unstable) cervical segments may move more than they normally do, which can result in spinal cord injury. The authors tested whether, during endotracheal intubation, intervertebral motion of an injured C3–4 cervical segment 1) is greater than that in the intact (stable) state and 2) differs when a high- or low-force laryngoscope is used.

METHODS

Fourteen cadavers underwent 3 intubations using force-sensing laryngoscopes while simultaneous cervical spine motion was recorded with lateral fluoroscopy. The first intubation was performed with an intact cervical spine and a conventional high-force line-of-sight Macintosh laryngoscope. After creation of a severe C3–4 distractive-flexion injury, 2 additional intubations were performed, one with the Macintosh laryngoscope and the other with a low-force indirect video laryngoscope (Airtraq), used in random order.

RESULTS

During Macintosh intubations, between the intact and the injured conditions, C3–4 extension (0.3° ± 3.0° vs 0.4° ± 2.7°, respectively; p = 0.9515) and anterior-posterior subluxation (−0.1 ± 0.4 mm vs −0.3 ± 0.6 mm, respectively; p = 0.2754) did not differ. During Macintosh and Airtraq intubations with an injured C3–4 segment, despite a large difference in applied force between the 2 laryngoscopes, segmental extension (0.4° ± 2.7° vs 0.3° ± 3.3°, respectively; p = 0.8077) and anterior-posterior subluxation (0.3 ± 0.6 mm vs 0.0 ± 0.7 mm, respectively; p = 0.3203) did not differ.

CONCLUSIONS

The authors' hypotheses regarding the relationship between laryngoscope force and the motion of an injured cervical segment were not confirmed. Motion-force relationships (biomechanics) of injured cervical intervertebral segments during endotracheal intubation in cadavers are not predicted by the in vitro biomechanical behavior of isolated cervical segments. With the limitations inherent to cadaveric studies, the results of this study suggest that not all forms of cervical spine injury are at risk for pathological motion and cervical cord injury during conventional high-force line-of-sight intubation.

A Comparison Between the Conventional and the Laryngoscope-Assisted Lightwand Intubation Techniques in Patients With Cervical Immobilization: A Prospective Randomized Study

BACKGROUND

Positioning of a lightwand in the midline of the oral cavity can be challenging in patients with cervical immobilization. Direct laryngoscopy may permit the lightwand tip to more easily access the glottic opening. We tested our hypothesis that a laryngoscope-assisted lightwand technique allows more successful endotracheal intubation than does a conventional lightwand approach.

METHODS

A total of 162 patients requiring cervical immobilization during intubation for cervical spine surgery were allocated randomly to 2 groups. The conventional lightwand technique (group C, n = 80) or the laryngoscope-assisted lightwand technique (group L, n = 82) was used for endotracheal intubation. In the group L, a Macintosh laryngoscope was inserted into the oral cavity, advanced until the epiglottis tip was visible, but not used to lift the epiglottis tip. The lightwand tip was placed below the epiglottis under direct view of the epiglottis tip. The primary outcome (the initial intubation success rate) and secondary outcomes (intubation time, hemodynamic changes, and postoperative airway complications) were evaluated.

RESULTS

The initial intubation success rate was significantly lower (75% vs 89%; relative risk [95% confidence interval]: 1.2 [1.0-1.4]; P = .034) in group C than group L. The intubation time (22 ± 13 vs 24 ± 12 seconds; mean difference [98.33% confidence interval]: 2.4 [-2.3 to 7.2]; P = .217) did not differ between groups. Postoperative sore throat score, incidences of hypertension and tachycardia, postoperative oral mucosal bleeding, and hoarseness also did not differ between groups.

CONCLUSIONS

Laryngoscope-assisted lightwand intubation did not increase intubation time, and it increased first attempt intubation rates compared with traditional lightwand intubation in patients requiring cervical immobilization for cervical spine surgery.

Intubation Biomechanics: Laryngoscope Force and Cervical Spine Motion during Intubation in Cadavers-Cadavers versus Patients, the Effect of Repeated Intubations, and the Effect of Type II Odontoid Fracture on C1-C2 Motion

BACKGROUND

The aims of this study are to characterize (1) the cadaver intubation biomechanics, including the effect of repeated intubations, and (2) the relation between intubation force and the motion of an injured cervical segment.

METHODS

Fourteen cadavers were serially intubated using force-sensing Macintosh and Airtraq laryngoscopes in random order, with simultaneous cervical spine motion recorded with lateral fluoroscopy. Motion of the C1-C2 segment was measured in the intact and injured state (type II odontoid fracture). Injured C1-C2 motion was proportionately corrected for changes in intubation forces that occurred with repeated intubations.

RESULTS

Cadaver intubation biomechanics were comparable with those of patients in all parameters other than C2-C5 extension. In cadavers, intubation force (set 2/set 1 force ratio = 0.61; 95% CI, 0.46 to 0.81; P = 0.002) and Oc-C5 extension (set 2 - set 1 difference = -6.1 degrees; 95% CI, -11.4 to -0.9; P = 0.025) decreased with repeated intubations. In cadavers, C1-C2 extension did not differ (1) between intact and injured states; or (2) in the injured state, between laryngoscopes (with and without force correction). With force correction, in the injured state, C1-C2 subluxation was greater with the Airtraq (mean difference 2.8 mm; 95% CI, 0.7 to 4.9 mm; P = 0.004).

CONCLUSIONS

With limitations, cadavers may be clinically relevant models of intubation biomechanics and cervical spine motion. In the setting of a type II odontoid fracture, C1-C2 motion during intubation with either the Macintosh or the Airtraq does not appear to greatly exceed physiologic values or to have a high likelihood of hyperextension or direct cord compression.

Controlled Laboratory Comparison Study of Motion With Football Equipment in a Destabilized Cervical Spine: Three Spine-Board Transfer Techniques

Background

Numerous studies have shown that there are better alternatives to log rolling patients with unstable spinal injuries, although this method is still commonly used for placing patients onto a spine board. No previous studies have examined transfer maneuvers involving an injured football player with equipment in place onto a spine board.

Purpose

To test 3 different transfer maneuvers of an injured football player onto a spine board to determine which method most effectively minimizes spinal motion in an injured cervical spine model.

Study Design

Controlled laboratory study.

Methods

Five whole, lightly embalmed cadavers were fitted with shoulder pads and helmets and tested both before and after global instability was surgically created at C5-C6. An electromagnetic motion analysis device was used to assess the amount of angular and linear motion with sensors placed above and below the injured segment during transfer. Spine-boarding techniques evaluated were the log roll, the lift and slide, and the 8-person lift.

Results

The 8-person lift technique resulted in the least amount of angular and linear motion for all planes tested as compared with the lift-and-slide and log-roll techniques. This reached statistical significance for lateral bending (P = .031) and medial-lateral translation (P = .030) when compared with the log-roll maneuver. The lift-and-slide technique was significantly more effective at reducing motion than the log roll for axial rotation (P = .029) and lateral bending (P = .006).

Conclusion

The log roll resulted in the most motion at an unstable cervical injury as compared with the other 2 spine-boarding techniques examined. The 8-person lift and lift-and-slide techniques may both be more effective than the log roll at reducing unwanted cervical spine motion when spine boarding an injured football player. Reduction of such motion is critical in the prevention of iatrogenic injury.

Alternative intubation techniques vs Macintosh laryngoscopy in patients with cervical spine immobilization: systematic review and meta-analysis of randomized controlled trials

Background. Immobilization of the cervical spine worsens tracheal intubation conditions. Various intubation devices have been tested in this setting. Their relative usefulness remains unclear.

Methods. We searched MEDLINE, EMBASE, and the Cochrane Library for randomized controlled trials comparing any intubation device with the Macintosh laryngoscope in human subjects with cervical spine immobilization. The primary outcome was the risk of tracheal intubation failure at the first attempt. Secondary outcomes were quality of glottis visualization, time until successful intubation, and risk of oropharyngeal complications.

Results. Twenty-four trials (1866 patients) met inclusion criteria. With alternative intubation devices, the risk of intubation failure was lower compared with Macintosh laryngoscopy [risk ratio (RR) 0.53; 95% confidence interval (CI) 0.35–0.80]. Meta-analyses could be performed for five intubation devices (Airtraq, Airwayscope, C-Mac, Glidescope, and McGrath). The Airtraq was associated with a statistically significant reduction of the risk of intubation failure at the first attempt (RR 0.14; 95% CI 0.06–0.33), a higher rate of Cormack–Lehane grade 1 (RR 2.98; 95% CI 1.94–4.56), a reduction of time until successful intubation (weighted mean difference −10.1 s; 95% CI −3.2 to −17.0), and a reduction of oropharyngeal complications (RR 0.24; 95% CI 0.06–0.93). Other devices were associated with improved glottis visualization but no statistically significant differences in intubation failure or time to intubation compared with conventional laryngoscopy.

Conclusions. In situations where the spine is immobilized, the Airtraq device reduces the risk of intubation failure. There is a lack of evidence for the usefulness of other intubation devices.

Clinical evaluation and airway management for adults with cervical spine instability

Airway management of patients with cervical spine instability may be difficult as a result of immobilization, and may be associated with secondary neurologic injury related to cervical spine motion. Spinal cord instability is most common in patients with trauma, but there are additional congenital and acquired conditions that predispose to subacute cervical spine instability. Patients with suspected instability should receive immobilization during airway management with manual in-line stabilization. The best strategy for airway management is one that applies the technique with the highest likelihood of success on the first attempt and the lowest biomechanical influence on a potentially unstable spine.

Laryngoscope and a new tracheal tube assist lightwand intubation in difficult airways due to unstable cervical spine

PURPOSE

The WEI Jet Endotracheal Tube (WEI JET) is a new tracheal tube that facilitates both oxygenation and ventilation during the process of intubation and assists tracheal intubation in patients with difficult airway. We evaluated the effectiveness and usefulness of the WEI JET in combination with lightwand under direct laryngoscopy in difficult tracheal intubation due to unstable cervical spine.

METHODS

Ninety patients with unstable cervical spine disorders (ASA I-III) with general anaesthesia were included and randomly assigned to three groups, based on the device used for intubation: lightwand only, lightwand under direct laryngoscopy, lightwand with WEI JET under direct laryngoscopy.

RESULTS

No statistically significant differences were detected among three groups with respect to demographic characteristics and C/L grade. There were statistically significant differences between three groups for overall intubation success rate (p = 0.015) and first attempt success rate (p = 0.000). The intubation time was significantly longer in the WEI group (110.8±18.3 s) than in the LW group (63.3±27.5 s, p = 0.000) and DL group (66.7±29.4 s, p = 0.000), but the lowest SpO2 in WEI group was significantly higher than other two groups (p<0.01). The WEI JET significantly reduced successful tracheal intubation attempts compared to the LW group (p = 0.043). The severity of sore throat was similar in three groups (p = 0.185).

CONCLUSIONS

The combined use of WEI JET under direct laryngoscopy helps to assist tracheal intubation and improves oxygenation during intubation in patients with difficult airway secondary to unstable spine disorders.

TRIAL REGISTRATION

Chinese Clinical Trial Registry ChiCTR-TRC-14005141.

Is it safe to use a kinetic therapy bed for care of patients with cervical spine injuries?

INTRODUCTION

Bedrest is often used for temporary management, as well as definitive treatment, for many spinal injuries. Under such circumstances patients cannot remain flat for extended periods due to possible skin breakdown, blood clots, or pulmonary complications. Kinetic therapy beds are often used in the critical care setting, although this is felt to be unsafe for turning patients with spine fractures. We sought to evaluate whether a kinetic therapy bed would cause as much spinal motion at an unstable cervical injury as occurs during manual log-rolling on a standard intensive care unit bed.

METHODS

Unstable C5-C6 ligamentous injuries were surgically created in 15 fresh, whole cadavers. Sensors were affixed to C5 and C6 posteriorly and electromagnetic motion tracking analysis performed. In all cases a cervical collar was applied by an orthotist after creation of the injury. The amount of angular motion and linear displacement that occurred at this injured level was measured during manual log-rolling and patient turning using a kinetic therapy bed. For statistical analysis, the range of motion for angles about each axis and displacement in each direction was analyzed by multivariate analysis of variance with repeated measures.

RESULTS

When comparing manual log-rolling and kinetic bed therapy, significantly more angular motion was created by the log-roll manoeuvre in flexion-extension (p=0.03) and lateral bending (p=0.01). There was no significant difference in axial rotation between the two methods (p=0.80). There were no significant differences demonstrated in medial-lateral and anterior-posterior translation. There was almost two times the axial displacement between manual log-rolling and the kinetic therapy bed and this reached statistical significance (p=0.05).

CONCLUSION

There is less motion at an unstable cervical injury in flexion-extension, lateral bending, and axial displacement when turning a patient using a kinetic therapy bed as opposed to traditional manual log-rolling. It may be preferable to use a kinetic therapy bed rather than manual log-rolling for patients with cervical spine injuries to decrease unwanted spinal motion. In addition, it may be easier and less physically demanding on nursing staff that must regularly turn the patient if manual log-rolling is implemented.

Cadaveric study of movement of an unstable atlanto-axial (C1/C2) cervical segment during laryngoscopy and intubation using the Airtraq(®) , Macintosh and McCoy laryngoscopes

Concern that laryngoscopy and intubation might create or exacerbate a spinal cord injury has generated extensive research into cervical spinal movement during laryngoscopy. We performed a randomised trial on six cadavers, using three different laryngoscopes, before and after creating a type-2 odontoid peg fracture. Our primary outcome measure was the change in the space available for the spinal cord at the C1/2 segment measured by cinefluoroscopy. Tracheal intubation was performed using a minimal view of the glottis, a bougie, and manual in-line stabilisation. In a cadaveric model of type-2 odontoid fracture, the space available for the cord was preserved in maximum flexion and extension, and changed little on laryngoscopy and intubation.

Intubation biomechanics: laryngoscope force and cervical spine motion during intubation with Macintosh and Airtraq laryngoscopes

INTRODUCTION

Laryngoscopy and endotracheal intubation in the presence of cervical spine instability may put patients at risk of cervical cord injury. Nevertheless, the biomechanics of intubation (cervical spine motion as a function of applied force) have not been characterized. This study characterized and compared the relationship between laryngoscope force and cervical spine motion using two laryngoscopes hypothesized to differ in force.

METHODS

Fourteen adults undergoing elective surgery were intubated twice (Macintosh, Airtraq). During each intubation, laryngoscope force, cervical spine motion, and glottic view were recorded. Force and motion were referenced to a preintubation baseline (stage 1) and were characterized at three stages: stage 2 (laryngoscope introduction); stage 3 (best glottic view); and stage 4 (endotracheal tube in trachea).

RESULTS

Maximal force and motion occurred at stage 3 and differed between the Macintosh and Airtraq: (1) force: 48.8 ± 15.8 versus 10.4 ± 2.8 N, respectively, P = 0.0001; (2) occiput-C5 extension: 29.5 ± 8.5 versus 19.1 ± 8.7 degrees, respectively, P = 0.0023. Between stages 2 and 3, the motion/force ratio differed between Macintosh and Airtraq: 0.5 ± 0.2 versus 2.0 ± 1.4 degrees/N, respectively; P = 0.0006.

DISCUSSION

The relationship between laryngoscope force and cervical spine motion is: (1) nonlinear and (2) differs between laryngoscopes. Differences between laryngoscopes in motion/force relationships are likely due to: (1) laryngoscope-specific cervical extension needed for intubation, (2) laryngoscope-specific airway displacement/deformation needed for intubation, and (3) cervical spine and airway tissue viscoelastic properties. Cervical spine motion during endotracheal intubation is not directly proportional to force. Low-force laryngoscopes cannot be assumed to result in proportionally low cervical spine motion.

Effect of rigid cervical collar on tracheal intubation using Airtraq(®)

Background and Aims:

Cervical spine immobilisation with rigid cervical collar imposes difficulty in intubation. Removal of the anterior part of the collar may jeopardize the safety of the cervical spine. The effect of restricted mouth opening and cervical spine immobilisation that result from the application of rigid cervical collar on intubation using Airtraq^® was evaluated.

Methods:

Seventy healthy adults with normal airways included in the study were intubated Using Airtraq® with (group C) and without rigid cervical collar (group NC). The ease of insertion of Airtraq^® into the oral cavity, intubation time, intubation difficulty score (IDS) were compared using Wilcoxon sign ranked test and McNemar test, using SPSS version 13.

Results:

Intubation using Airtraq^® was successful in the presence of the cervical collar in 96% which was comparable to group without collar (P = 0.24). The restriction of mouth opening resulted in mild difficulty in insertion of Airtraq^®. The median Likert scale for insertion was - 1 in the group C and + 1 in group NC (P < 0.001). The intubation time was longer in group C (30 ± 14.3 s vs. 26.9 ± 14.8 s) compared to group NC. The need for adjusting manoeuvres was 18.5% in group C versus 6.2% in group NC (P = 0.003) and bougie was required in 12 (18.5%) and 4 (6.2%) patients in group C and NC, respectively, to facilitate intubation (P = 0.02). The modified IDS score was higher in group C but there was no difference in the number of patients with IDS < 2.

Conclusion:

Tracheal intubation using Airtraq^® in the presence of rigid cervical collar has equivalent success rate, acceptable difficulty in insertion and mild increase in IDS.

Upper cervical spine movement during intubation with different airway devices

Prevention of secondary neurologic injury is critical during the airway management of a trauma patient. Trauma patients are assumed to have an unstable cervical spine (C-spine) until proven otherwise: orotracheal intubation during airway management may result in a certain amount of C-spine movement. This study, therefore, aimed to compare C-spine movement within different advanced airway devices (Macintosh blade, McCoy Blade, LMA, I-LMA, and Combitube) during airway management.

MATERIALS AND METHODS

A total of 3 fresh frozen cadavers were used. The cadavers were consecutively intubated by 4 different postgraduate year residents with LMA4, I-LMA5, Combitube (37F), Macintosh 3, and McCoy blades. The cinefluoroscopic view of the entire intubation process was recorded, and vertebral body angles were calculated.

RESULTS

At the C0C1 level, compared with the McCoy laryngoscope (median, 7°), the LMA (median, 2.5°) and the Combitube (median, 1.5°) caused less extension of the cervical vertebra. In addition, the Combitube (median, -1°) and the I-LMA (median, -2°) caused less extension of the C2C3 region when compared with the Macintosh laryngoscope (median, 3°). There was no significant difference between groups at the C1C2, C3C4, and C4C5 segments.

CONCLUSION

Supraglottic devices used during airway management cause C-spine movement less or equal to conventional laryngoscopes. Furthermore, because of ease of training and blind insertion, supraglottic devices can be safely used with trauma patients when C-spine integrity is a concern.

[Anesthesiological considerations for patients with trisomy 21 (Down syndrome)]

The most common chromosomal abnormality is trisomy 21 which is also known as Down syndrome and occurs in approximately 1 in 800 births. The majority of the resulting disabling conditions cannot be cured and affect people of all ages, ethnicity and economic levels. Life expectancy has increased with advances in medical care in the same way as in the rest of the population. One of the major tasks for health care professionals is to help these differently abled children and their families function in the most effective way possible as they learn to accept the limitations imposed by a persistent disability. Signs and symptoms of trisomy 21 are very variable based on the trias of mental retardation to a variable degree, hand anomalies and cardiac complications. Other abnormalities are atlantoaxial instability (AAI), tracheal stenosis, a predisposition to respiratory complications, chronic hypothyroidism, microgenia and macroglossia. These conditions are relevant to anesthetic procedures and patients with Down syndrome and their families have specific expectations and attitudes towards medical and anesthetic treatment.

A comparison of 4 airway devices on cervical spine alignment in cadaver models of global ligamentous instability at c1-2

BACKGROUND

The effects of advanced airway management on cervical spine alignment in patients with upper cervical spine instability are uncertain.

METHODS

To examine the potential for mechanical disruption during endotracheal intubation in cadavers with unstable cervical spines, we performed a prospective observational cohort study with 3 cadaver subjects. We created an unstable, type II odontoid fracture with global ligamentous instability at C1-2 in lightly embalmed cadavers, followed by repetitive intubations with 4 different airway devices (Airtraq laryngoscope, Lightwand, intubating laryngeal mask airway [LMA], and Macintosh laryngoscope) while manual in-line stabilization was applied. Motion analysis data were collected using an electromagnetic device to assess the degree of angular movement in 3 axes (flexion-extension, axial rotation, and lateral bending) during the intubation trials with each device. Intubation was performed by either an emergency medical technician or attending anesthesiologist.

RESULTS

Overall, 153 intubations were recorded with the 4 devices. The Lightwand technique resulted in significantly less flexion-extension and axial rotation at C1-2 than with the intubating LMA (mean difference in flexion-extension 3.2° [95% confidence interval {CI}, 0.9°-5.5°], P = 0.003; mean difference in axial rotation 1.6° [95% CI, 0.3°-2.8°], P = 0.01) and Macintosh laryngoscope (mean difference in flexion-extension 3.1° [95% CI, 0.8°-5.4°], P = 0.005; mean difference in axial rotation 1.4° [95% CI 0.1°-2.6°], P = 0.03).

CONCLUSIONS

In cadavers with instability at C1-2, the Lightwand technique produced less motion than the Macintosh and intubating LMA.