A methodology to evaluate motion of the unstable spine during intubation techniques

Airway management in patients with suspected or confirmed traumatic spinal cord injury: a narrative review of current evidence

Around 1 million people sustain a spinal cord injury each year, which can have significant psychosocial, physical and socio‐economic consequences for patients, their families and society. The aim of this review is to provide clinicians with a summary of recent studies of direct relevance to the airway management of patients with confirmed or suspected traumatic spinal cord injury to promote best clinical practice. All airway interventions are associated with some degree of movement of the cervical spine; in general, these are very small and whether these are clinically significant in terms of impingement of the spinal cord is unclear. Manual in‐line stabilisation does not effectively immobilise the cervical spine and increases the likelihood of difficult and failed tracheal intubation. There is no clear evidence of benefit of awake tracheal intubation techniques in terms of prevention of secondary spinal cord injury. Videolaryngoscopy appears to cause a similar degree of cervical spine displacement as flexible bronchoscope‐guided tracheal intubation and is an appropriate alternative approach. Direct laryngoscopy does cause a slightly greater degree of cervical spinal movement during tracheal intubation than videolaryngoscopy, but this does not appear to increase the risk of spinal cord compression. The risk of spinal cord injury during tracheal intubation appears to be minimal even in the presence of gross cervical spine instability. Depending on the clinical situation, practitioners should choose the tracheal intubation technique with which they are most proficient and that is most likely to minimise cervical spine movement.

Fiberoptic bronchoscopy versus video laryngoscopy guided intubation in patients with craniovertebral junction instability: A cinefluroscopic comparison

Background:

Manipulation during endotracheal intubation in patients with craniovertebral junction (CVJ) anomalies may cause neurological deterioration due to underlying instability. Fiberoptic-bronchoscopy (FOB) is better than video laryngoscope (VL) for minimizing cervical spine movement during intubation. However, evidence suggesting superiority of FOB in patients with CVJ instability is lacking. We prospectively compared dynamic movements of the upper cervical spine during intubation using FOB with VL in patients with CVJ anomalies.

Methods:

A prospective, randomized, and clinical trial was conducted in 62 patients of American Society of Anaesthesiologist Grade I-II aged between 12 and 65 years with CVJ anomalies. Patients were randomized for intubation under general anesthesia with either VL or FOB. The intubation process was done with application of skeletal traction and recorded cinefluroscopically. The dynamic interrelationship of bony landmarks (horizontal, vertical, and diagonal distances between fixed points on posterior C1 and C2) was analyzed to indirectly calculate alteration of the upper cervical spinal canal diameter (at CVJ). Atlanto-dental interval (ADI) was calculated wherever possible.

Results:

The alteration in canal diameter (using bony landmarks) at CVJ during intubation was not significant with the use of either VL or FOB (P > 0.05). In 41 patients, where ADI could be measured, ADI was reduced (increased spinal canal diameter) in a greater number of patients in VL group when compared to FOB group (P < 0.05).

Conclusion:

Using rigid skull traction, intubation under general anesthesia with VL offers similar advantage as FOB in terms of the spinal kinematics in patients with CVJ anomalies/instability. Nevertheless, greater number of patients intubated with VL may have an advantage of increased cervical spinal canal diameter when compared to FOB.

The Clinical Use of Cricoid Pressure: First, Do No Harm

Application of cricoid pressure (CP) during rapid sequence induction and intubation sequence has been a "standard" of care for many decades, despite limited scientific proof of its efficacy in preventing pulmonary aspiration of gastric contents. While some of the current rapid sequence induction and intubation guidelines recommend its use, other international guidelines do not, and many clinicians argue that there is insufficient evidence to either continue or abandon its use. Recently published articles and accompanying editorials have reignited the debate on the efficacy and safety of CP application and have generated multiple responses that pointed out the various (and significant) limitations of the available evidence. Thus, a critical discussion of available data must be undertaken before making a final clinical decision on such an important patient safety issue. In this review, the authors will take an objective look at the available scientific evidence about the effectiveness and safety of CP in patients at risk of pulmonary aspiration of gastric contents. We suggest that current data are inadequate to impose clinical guidelines on the use of CP because we acknowledge that currently there is not, and there may never be, a method to prevent aspiration in all patients. In addition, we reiterate that a universally accepted medical-legal standard for approaching the high-risk aspiration patient does not exist, discuss the differences in practice between the US and international practitioners regarding use of CP, and propose 5 recommendations on how future studies might be designed to obtain optimal scientific evidence about the effectiveness and safety of CP in patients at risk for pulmonary aspiration.

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.

Cricoid Pressure Controversies

Since cricoid pressure was introduced into clinical practice, controversial issues have arisen, including necessity, effectiveness in preventing aspiration, quantifying the cricoid force, and its reliability in certain clinical entities and in the presence of gastric tubes. Cricoid pressure–associated complications have also been alleged, such as airway obstruction leading to interference with manual ventilation, laryngeal visualization, tracheal intubation, placement of supraglottic devices, and relaxation of the lower esophageal sphincter. This review synthesizes available information to identify, address, and attempt to resolve the controversies related to cricoid pressure. The effective use of cricoid pressure requires that the applied force is sufficient to occlude the esophageal entrance while avoiding airway-related complications. Most of these complications are caused by excessive or inadequate force or by misapplication of cricoid pressure. Because a simple-to-use and reliable cricoid pressure device is not commercially available, regular training of personnel, using technology-enhanced cricoid pressure simulation, is required. The current status of cricoid pressure and objectives for future cricoid pressure–related research are also discussed.

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.

Airway management in a patient with nuchal, interspinous, and flavum ligament rupture by a sickle: a case report

BACKGROUND

Penetrating neck injury is an important trauma subset but is relatively rare, especially when involving the posterior cervical column. Rupture of the neck restraints, including the interspinous and flavum ligaments, can create serious cervical instability that requires special consideration when managing the airway. However, no detailed information regarding airway management in patients with profound posterior neck muscle laceration and direct cervical ligament disruption by an edged weapon is yet available in the literature.

CASE PRESENTATION

A 63-year-old Japanese man attempted to cut off his head using a sickle after drinking a copious amount of alcohol. On admission, his posterior vertebral column was grossly exposed and the lacerated tissues were actively bleeding, resulting in severe hypovolemic shock. We used a rapid-sequence intubation technique with direct laryngoscopy while manual in-line stabilization of his head and neck was maintained by several people. Surgical exploration revealed nuchal, interspinous, and flavum ligament rupture between his fourth and fifth cervical vertebrae, but no injury to the great vessels was present. The major source of bleeding was a site of oozing from his trapezius and splenius muscles. After surgical hemostasis, wound repair, and subsequent intensive care, our patient was discharged home without any neurological sequelae.

CONCLUSIONS

Deficits of the neck restraints can cause cervical spine subluxation and dislocation secondary to neck movement. Thus, the key to successful airway management in such a scenario is minimization of neck movement to prevent further neurological impairment. We successfully managed an airway using a conventional but trusted endotracheal intubation strategy in a patient with multiple traumas and a suspected spinal cord injury. This case also illustrates that, even when great vessel injury is absent, severe hypovolemic shock may occur after profound neck muscle laceration, requiring immediate surgical intervention.

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.

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

STUDY DESIGN

Human cadaveric study using various intubation devices in a cervical spine instability model.

OBJECTIVE

We sought to evaluate various intubation techniques and determine which device results in the least cervical motion in the setting of a global ligamentous instability model.

SUMMARY OF BACKGROUND DATA

Many patients presenting with a cervical spine injury have other injuries that may require rapid airway management with endotracheal intubation. Secondary neurologic injuries may occur in these patients because of further displacement at the level of injury, vascular insult, or systemic decrease in oxygen delivery. The most appropriate technique for achieving endotracheal intubation in the patient with a cervical spine injury remains controversial.

METHODS

A global ligamentous instability at the C5-C6 vertebral level was created in lightly embalmed cadavers. An electromagnetic motion analysis device (Liberty; Polhemus, Colchester, VT) was used to assess the amount of angular and linear translation in 3 planes during intubation trials with each of 4 devices (Airtraq laryngoscope, lighted stylet, intubating LMA, and Macintosh laryngoscope). The angular motions measured were flexion-extension, axial rotation, and lateral bending. Linear translation was measured in the medial-lateral (ML), axial, and anteroposterior planes. Intubation was performed by either an emergency medical technician or by a board-certified attending anesthesiologist. Both time to intubate as well as failure to intubate (after 3 attempts) were recorded.

RESULTS

There was no significant difference shown with regards to time to successfully intubate using the various devices. It was shown that the highest failure-to-intubate rate occurred with use of the intubating LMA (ILMA) (23%) versus 0% for the others. In flexion/extension, we were able to demonstrate that the Lightwand (P = 0.005) and Airtraq (P = 0.019) resulted in significantly less angular motion than the Macintosh blade. In anterior/posterior translation, the Lightwand (P = 0.005), Airtraq (P = 0.024), and ILMA (P = 0.021) all caused significantly less linear motion than the Macintosh blade. In axial rotation, the Lightwand (P = 0.017) and Airtraq (P = 0.022) resulted in significantly less angular motion than the Macintosh blade. In axial translation (P = 0.037) and lateral bending (P = 0.003), the Lightwand caused significantly less motion than the Macintosh blade.

CONCLUSION

In a cadaver model of C5-C6 instability, the greatest amount of motion was caused by the most commonly used intubation device, the Macintosh blade. Intubation with the Lightwand resulted in significantly less motion in all tested parameters (other than ML translation) as compared with the Macintosh blade. It should also be noted that the Airtraq caused less motion than the Macintoshblade in 3 of the 6 tested planes. There were no significant differences in failure rate or the amount of time it took to successfully intubate in comparing these techniques. We therefore recommend the use of the Lightwand, followed by the Airtraq, in the setting of a presumed unstable cervical spine injury over the Macintosh laryngoscope.

Cervical spine trauma in children and adults: perioperative considerations

A wide spectrum of cervical spine injuries, including stable and unstable injuries with and without neurologic compromise, account for a large percentage of emergency department visits. Effective treatment of the polytrauma patient with cervical spine injury requires knowledge of cervical spine anatomy and the pathophysiology of spinal cord injury, as well as techniques for cervical spine stabilization, intraoperative positioning, and airway management. The orthopaedic surgeon must oversee patient care and coordinate treatment with emergency department physicians and anesthesia services in both the acute and subacute settings. Children are particularly susceptible to substantial destabilizing cervical injuries and must be treated with a high degree of caution. The surgeon must understand the unique anatomic and biomechanical properties associated with the pediatric cervical spine as well as injury patterns and stabilization techniques specific to this patient population.

Cricoid pressure and laryngeal manipulation in 402 pre-hospital emergency anaesthetics: essential safety measure or a hindrance to rapid safe intubation?

OBJECTIVES

This is the first study to look at the effects of cricoid pressure/laryngeal manipulation on the laryngeal view and intubation success in the emergency or pre-hospital environment. Cricoid pressure is applied in the hope of reducing the incidence of aspiration. However the technique has never been evaluated in a randomized trial and may adversely affect laryngeal view. In order to improve intubating conditions cricoid pressure may be released and the larynx manipulated into a more favourable position.

METHODS

We carried out a prospective observational study to evaluate the effects of cricoid pressure and laryngeal manipulation on laryngeal view in our physician led pre-hospital trauma service.

RESULTS

402 patients were included over a 16-month period. We intubated 98.8% patients on the first or second attempt. In 61 intubations (in 55 patients, 13.6%) the larynx required manipulation to facilitate intubation. In 22 intubations cricoid pressure was removed with the laryngeal view improving in 50%. Bimanual laryngeal manipulation was used in 25 intubations and the larynx better visualised in 60% of these. Backwards upwards rightwards pressure was applied to the larynx in 14 intubations and the laryngeal view improved in 64%. Two patients regurgitated when cricoid pressure was released. Both had prolonged periods of bag valve mask ventilation and difficult intubations.

DISCUSSION

The results suggest that cricoid pressure should be removed if the laryngeal view obtained is not sufficient to allow immediate intubation. Further manipulation of the larynx is likely to improve the chances of successful tracheal tube placement.

Cervical spine motion during flexible bronchoscopy compared with the Lo-Pro GlideScope

BACKGROUND

The most appropriate device for tracheal intubation in patients with potential cervical spine injury remains controversial. We hypothesized that the Lo-Pro GlideScope (LP-G) videolaryngoscope would not cause significantly greater cervical spine movement than fibreoptic bronchoscopy even in the non-immobilized spine.

METHODS

Twenty-eight healthy adults requiring intubation for radiographic procedures were randomized to either the LP-G or the flexible bronchoscope (FB) devices. Continuous fluoroscopy was used to assess cervical spine movement during tracheal intubation. The point of maximum movement was compared with baseline for change in angulation between Occiput (Occ)-C1, Occ-C2, Occ-C4, Occ-C5, C1-2, C2-4, and C4-5. Measurements were made by two independent observers. The change in angulation was also measured for tongue pull and jaw thrust, manoeuvres for enlarging the pharyngeal space, before FB intubation.

RESULTS

LP-G resulted in greater cervical extension compared with FB for every angle calculated, statistically significant between Occ-C1 (P<0.05), Occ-C2 (P<0.05), and Occ-C4 (P<0.01). Tongue pull resulted in significantly less cervical spine motion than FB intubation at Occ-C1, Occ-C2, Occ-C4, and Occ-C5 (P<0.05). When jaw thrust was added to tongue pull, there was a tendency for greater movement than FB intubation at Occ-C1, Occ-C2, and Occ-C3. This was statistically significant at Occ-C1 and Occ-C3 (P<0.05) for one of the two observers.

CONCLUSIONS

During intubation under general anaesthesia, LP-G resulted in greater cervical movement than FB when no cervical immobilization was used in adults without cervical disease. Airway manoeuvres performed before FB, especially jaw thrust, also resulted in cervical spine movement.

The 6-plus-person lift transfer technique compared with other methods of spine boarding

CONTEXT

To achieve full spinal immobilization during on-the-field management of an actual or potential spinal injury, rescuers transfer and secure patients to a long spine board. Several techniques can be used to facilitate this patient transfer.

OBJECTIVE

To compare spinal segment motion of cadavers during the execution of the 6-plus-person (6+) lift, lift-and-slide (LS), and logroll (LR) spine-board transfer techniques.

DESIGN

Crossover study.

SETTING

Laboratory.

PATIENTS OR OTHER PARTICIPANTS

Eight medical professionals (1 woman, 7 men) with 5 to 32 years of experience were enlisted to help carry out the transfer techniques. In addition, test conditions were performed on 5 fresh cadavers (3 males, 2 females) with a mean age of 86.2 +/- 11.4 years.

MAIN OUTCOMES MEASURE(S)

Three-dimensional angular and linear motions initially were recorded during execution of transfer techniques, initially using cadavers with intact spines and then after C5-C6 spinal segment destabilization. The mean maximal linear displacement and angular motion obtained and calculated from the 3 trials for each test condition were included in the statistical analysis.

RESULTS

Flexion-extension angular motion, as well as anteroposterior and distraction-compression linear motion, did not vary between the LR and either the 6+ lift or LS. Compared with the execution of the 6+ lift and LS, the execution of the LR generated significantly more axial rotation (P = .008 and .001, respectively), more lateral flexion (P = .005 and .003, respectively), and more medial-lateral translation (P = .003 and .004, respectively).

CONCLUSIONS

A small amount of spinal motion is inevitable when executing spine-board transfer techniques; however, the execution of the 6+ lift or LS appears to minimize the extent of motion generated across a globally unstable spinal segment.

Cricoid Pressure in Emergency Department Rapid Sequence Tracheal Intubations: A Risk-Benefit Analysis

Cricoid pressure is considered an integral part of patient safety in rapid sequence tracheal intubation and emergency airway management. Cricoid pressure is applied to prevent the regurgitation of gastric contents into the pharynx and subsequent aspiration into the pulmonary tree. This review analyzes the published evidence supporting cricoid pressure, along with potential problems, including increased difficulty with tracheal intubation and ventilation. According to the evidence available, the universal and continuous application of cricoid pressure during emergency airway management is questioned. An awareness of the benefits and potential problems with technique allows the practitioner to better judge when cricoid pressure should be used and instances in which it should be removed.

Manual In-Line Stabilization for Acute Airway Management of Suspected Cervical Spine Injury: Historical Review and Current Questions

Direct laryngoscopy with manual in-line stabilization is standard of care for acute trauma patients with suspected cervical spine injury. Ethical and methodologic constraints preclude controlled trials of manual in-line stabilization, and recent work questions its effectiveness. We searched MEDLINE, Index Medicus, Web of Knowledge, the Cochrane Database, and article reference lists. According to this search, we present an ancestral review tracing the origins of manual in-line stabilization and an analysis of subsequent studies evaluating the risks and benefits of the procedure. All manual in-line stabilization data came from trials of uninjured patients, cadaveric models, and case series. The procedure was adopted because of reasonable inference from the benefits of stabilization during general care of spine-injured patients, weak empirical data, and expert opinion. More recent data indicate that direct laryngoscopy and intubation are unlikely to cause clinically significant movement and that manual in-line stabilization may not immobilize injured segments. In addition, manual in-line stabilization degrades laryngoscopic view, which may cause hypoxia and worsen outcomes in traumatic brain injury. Patients intubated in the emergency department with suspected cervical spine injury often have traumatic brain injury, but the incidence of unstable cervical lesions in this group is low. The limited available evidence suggests that allowing some flexion or extension of the head is unlikely to cause secondary injury and may facilitate prompt intubation in difficult cases. Despite the presumed safety and efficacy of direct laryngoscopy with manual in-line stabilization, alternative techniques that do not require direct visualization warrant investigation. Promising techniques include intubation through supraglottic airways, along with video laryngoscopes, optical stylets, and other imaging devices.

In vivo ultrasound real-time motion of the cervical spine during intubation under manual in-line stabilization: a comparison of intubation methods

BACKGROUND AND OBJECTIVE

In emergency trauma situations, manual in-line stabilization of the cervical spine is recommended to reduce cervical spine movement during intubation. The aim of this study was to compare the effect of manual in-line stabilization during different intubation techniques on three-dimensional cervical spine movements and times to intubation.

METHODS

Forty-eight subjects without any history of trauma, inflammatory or degenerative disorder of the cervical spine were randomly grouped, regardless of gender or age. All underwent elective surgery under general anaesthesia. Under manual in-line stabilization, laryngeal intubation with Macintosh laryngoscope, intubating laryngeal mask airway, fibre-endoscopic oral intubation and fibre-endoscopic nasal intubation was performed. During the intubation process, cervical three-dimensional motion was detected by an ultrasound real-time motion analysis system and intubation times were measured.

RESULTS

Cervical spine range in the extension/flexion direction of orolaryngeal intubation with Macintosh (17.57 +/- 8.23 degrees ) showed significantly more movement than using the intubating laryngeal mask airway (4.60 +/- 1.51 degrees ) and fibreoptic procedures. Intubating laryngeal mask airway was significantly different than the fibreoptic intubation techniques. There was also a significant difference between oral (3.61 +/- 2.25 degrees ) nasal and (5.88 +/- 3.11 degrees ) fibreoptic intubation. Times to intubation all differed significantly (P < 0.05) for the Macintosh laryngoscope (27.25 +/- 8.56 s) and for the intubating laryngeal mask airway (16.5 +/- 9.76 s). Fibreendoscopic laryngoscopic oral (52.91 +/- 56.27 s) and nasal (82.32 +/- 54.06 s) intubation resulted in further prolongation of the times to intubation.

CONCLUSIONS

The intubating laryngeal mask airway with manual in-line stabilization is a potentially useful adjunct to intubation of patients with potential cervical spine injury, if there are no contraindications to these methods. These results predict that fibreoptic procedures may be a safe instrument for airway management in patients with potential cervical spine injuries; however, the main disadvantages are the longer intubation times.

Geriatric trauma: special considerations in the anesthetic management of the injured elderly patient

Modern society is characterized as having an ever enlarging population of older adults. There are more elderly patients, and the average age of this group is increasing. The anesthetic management of surgery for the elderly trauma victim is more complicated than in younger adults. Evaluation of the physiologic status of the geriatric patient should take into account the variability of the changes associated with advancing age. Care of the injured elderly patient requires thorough preoperative assessment and planning and the involvement of a multidisciplinary clinical team knowledgeable about and interested in the management of the elderly surgical patient.

Potential cervical spine injury and difficult airway management for emergency intubation of trauma adults in the emergency department--a systematic review

BACKGROUND

Emergency airway management for trauma adults is practised by physicians from a range of training backgrounds and with differing levels of experience. The indications for intubation and technique employed are factors that vary within EDs and between hospitals.

OBJECTIVES

To provide practical evidence based guidance for airway management in trauma resuscitation: first for the trauma adult with potential cervical spine injury and second the management when a difficult airway is encountered at intubation.

SEARCH STRATEGY AND METHODOLOGY

Full literature search for relevant articles in Medline (1966-2003), EMBASE (1980-2003), and the Cochrane Central Register of Controlled Trials. Relevant articles relating to adults and written in English language were appraised. English language abstracts of foreign articles were included. Studies were critically appraised on a standardised data collection sheet to assess validity and quality of evidence. The level of evidence was allocated using the methods of the Australian National Health and Medical Research Council.

Central cord syndrome after total hip arthroplasty: a patient report

STUDY DESIGN

Case report.

OBJECTIVE

To present a patient with central cord syndrome injury after total hip arthroplasty performed under general endotracheal anesthesia.

SUMMARY OF BACKGROUND DATA

Central cord syndrome, a common injury usually sustained as a result of an extension injury to the cervical spine, often occurs in geriatric patients with underlying spondylotic changes. The injury results in weakness and sensory changes, which are more pronounced in the upper than in the lower extremities. Patients with this syndrome experience variable return of function, but some degree of residual deficit and spasticity is likely.

METHODS

The medical record, including the intraoperative anesthesia records, operative notes, progress notes, discharge summary, clinic notes, and radiology studies and reports, was reviewed.

RESULTS

The patient developed signs of central cord syndrome after total hip arthroplasty. Despite nonoperative intervention, including physiotherapy, the patient's upper and lower extremity weakness continued. Magnetic resonance imaging revealed evidence of cervical cord compression, and the patient underwent a cervical laminectomy, which produced mild improvement in his symptoms.

CONCLUSIONS

To avoid life-altering complications, it is important to evaluate the cervical spine (especially in the elderly), avoid neck extension during intubation, and use careful airway management in patients with suspected stenosis/spondylosis.

Anesthetic management of a patient in prone position with a drill bit penetrating the spinal canal at C1-C2, using a laryngeal mask

Airway management in patients with penetrating neck trauma must guarantee cervical spine stability. Moreover, the prone position increases the risk of difficult ventilation and cervical spine injury. A 19-yr-old patient was brought to the emergency room in prone position with a drill bit protruding from the posterolateral aspect of his neck. The bit had entered the spinal canal below the first cervical vertebra, and placed near the odontoid peg. He was referred for surgical removal of the drill. The use of an inhaled induction of anesthesia, avoiding muscle relaxants, and ventilation through a laryngeal mask airway inserted in the prone position seemed to offer a satisfactory approach.

IMPLICATIONS

Management of patients with penetrating neck trauma must guarantee cervical spine stability. Moreover, the prone position increases the risk of difficult ventilation and cervical spine injury. Anesthesia may be induced and the airway can be managed with the patient already in the prone position for surgery.

Anesthetic management of traumatic brain injury

The management of TBI remains an important and frustrating component of the practice of anesthesiology and critical care medicine. The difficulties in management of TBI as well as the poor response rates to medical therapy after TBI are not new. The following passage appeared in the introductory chapter of a text on TBI from 1897: "The manner of treatment is of importance in only a minority of cases, since many subjects of intracranial injury are fated to die whatever measures may be adopted for their relief, and a still greater number are destined to recover though left entirely to the resources of nature. It is probable that in by far the larger proportion of cases in which the issue is determined by treatment it is met in the initial stage, and by insuring restoration from primary shock" [111]. Although secondary insults from factors such as hypotension, hypoxemia, and hyperventilation increase morbidity and mortality, data are not yet available to indicate whether scrupulous prevention and prompt treatment of secondary injuries will reduce morbidity and mortality. In addition, no specific intervention to date has improved overall long-term outcome. With ongoing research, perhaps active interventions will become available. Until that time, thoughtful and careful attention to physiologic management provides the greatest opportunity for a good outcome.

Cervical spine injury and airway management

Cervical spine injuries occur in 2-5% of blunt trauma patients, and 1-5% of these injuries are initially missed. Data from the large National Emergency X-Radiography Utilisation Study have helped to define the problem in some detail. There is a consensus on how to clear the cervical spine in patients who are alert, but in patients with altered mental status the choice of strategy for spinal clearance is more controversial. Despite obtaining extensive radiological studies, some clinicians will not clear the patient's cervical spine until full recovery of consciousness. As long as manual in-line neck stabilization is applied, rapid sequence induction of anaesthesia, followed by direct laryngoscopy and oral intubation appears to be safe in the patient with a cervical spine injury. If intubation is not urgent, an awake fibreoptic technique is a useful option. If intubation of the patient with a potential cervical spine injury fails, or appropriate experienced personnel are unavailable, the laryngeal mask airway or one of its various modifications are useful alternatives.

The effect of single-handed cricoid pressure on cervical spine movement after applying manual in-line stabilisation -- a cadaver study

Six adult cadavers had 40 N cricoid pressure applied using a cricoid 'yoke' whilst maintaining manual in-line stabilisation of the cervical spine. No other spinal supports were used. Lateral radiographs were taken before and after applying pressure to the cricoid cartilage and the degree of cervical spine movement accurately determined. The median vertical displacements measured from the body of C5 and two other reference points (A and B) on the cervical spine were 0.5 mm (range 0-1.5 mm) and 0.5 mm (range 0-3 mm), respectively. There was no disruption to the lines formed by the anterior or posterior borders of the cervical bodies. We have been unable to demonstrate that single-handed cricoid pressure causes clinically significant displacement of the cervical spine in a cadaver model. This conflicts with previous studies.

Cervical spinal motion during intubation: efficacy of stabilization maneuvers in the setting of complete segmental instability

OBJECT

The purpose of this study was to characterize and compare segmental cervical motion during orotracheal intubation in cadavers with and without a complete subaxial injury, as well as to examine the efficacy of commonly used stabilization techniques in limiting that motion.

METHODS

Intubation procedures were performed in 10 fresh human cadavers in which cervical spines were intact and following the creation of a complete C4-5 ligamentous injury. Movement of the cervical spine during direct laryngoscopy and intubation was recorded using video fluoroscopy and examined under the following conditions: 1) without stabilization; 2) with manual in-line cervical immobilization; and 3) with Gardner-Wells traction. Subsequently, segmental angular rotation, subluxation, and distraction at the injured C4-5 level were measured from digitized frames of the recorded video fluoroscopy.

CONCLUSIONS

After complete C4-5 destabilization, the effects of attempted stabilization on distraction, angulation, and subluxation were analyzed. Immobilization effectively eliminated distraction, and diminished angulation, but increased subluxation. Traction significantly increased distraction, but decreased angular rotation and effectively eliminated subluxation. Orotracheal intubation without stabilization had intermediate results, causing less distraction than traction, less subluxation than immobilization, but increased angulation compared with either intervention. These results are discussed in terms of both statistical and clinical significance and recommendations are made.

Tracheal intubation and cervical spine excursion: direct laryngoscopy vs. intubating laryngeal mask

Until recently, the most appropriate technique of intubating a patient with a cervical spine injury has been the subject of debate. Tracheal intubation by means of the intubating laryngeal mask (Fastrach), a modified conventional laryngeal mask airway, seems to require less neck manipulation. The aim of this study was to compare the excursion of the upper cervical spine during tracheal intubation using direct laryngoscopy with that during intubation via the laryngeal mask (Fastrach), by examination of lateral cervical spine radiographs in healthy young patients. The intubating laryngeal mask (Fastrach) caused less extension (at C1-2 and C2-3) than intubation by direct laryngoscopy. Direct laryngoscopy is still the fastest method to secure an airway provided no intubating difficulties are present. However, in trauma patients requiring rapid sequence induction and in whom cervical spine movement is limited or undesirable, the intubating laryngeal mask (Fastrach) is a safe and fast method by which to secure the airway.

Effect of surgical cricothyrotomy on the unstable cervical spine in a cadaver model of intubation

Cricothyrotomy is indicated for patients who require an immediate airway and in whom orotracheal or nasotracheal intubation is unsuccessful or contraindicated. Cricothyrotomy is considered safe with cervical spine (c-spine) injury; however, the amount of c-spine movement that occurs during the procedure has not been determined. In this experimental study, an established cadaver model of c-spine injury was used to quantify movement during cricothyrotomy. A complete C5--6 transection was performed by using an osteotome on 13 fresh-frozen cadavers. Standard open cricothyrotomy was performed on each cadaver, with c-spine images recorded in real time on fluoroscopy, then transferred to video and Kodachrome still images. Outcome measures included movement across the C5--6 site with regard to angulation expressed in degrees of rotation and linear measures of axial distraction and anterior-posterior (AP) displacement expressed as a proportion of C5 body width. Data were analyzed by using descriptive statistics to determine mean change from baseline in each of three planes of movement. Significance was assumed if 95% confidence intervals did not include zero. A significant amount of movement was observed with regard to AP displacement (6.3% of C5 width) and axial distraction (-4.5% of C5 width, indicating narrowing of the intervertebral space). These correspond to 1--2 mm AP displacement and less than 1 mm axial compression. No significant angular displacement was observed. In conclusion, cricothyrotomy results in a small but significant amount of movement across an unstable c-spine injury in a cadaver model. This degree of movement is less than the threshold for clinical significance.

Cervical spine motion during airway management: a cinefluoroscopic study of the posteriorly destabilized third cervical vertebrae in human cadavers

We conducted a randomized, controlled, crossover study to determine cervical spine motion for six airway management techniques in human cadavers with a posteriorly destabilized third cervical (C-3) vertebra. A destabilized C-3 segment was created in 10 cadavers (6-24 h postmortem). Cervical motion was recorded by continuous lateral fluoroscopy. The following airway management techniques were performed in random order on each cadaver with manual in-line stabilization applied: face mask ventilation (FM), laryngoscope-guided orotracheal intubation (OETT), fiberscope-guided nasal intubation (FOS-NETT), esophageal tracheal Combitube((R)) (Kendall-Sheridan, Neustadt, Germany) insertion (ETC), intubating laryngeal mask insertion with fiberscope-guided tracheal intubation (ILM-OETT), and laryngeal mask airway insertion (LMA). Afterward, maximum head-neck flexion (FLEX-MAX) and maximum head-neck extension (EXT-MAX) without manual in-line stabilization was performed to determine maximum motion. The maximum posterior displacement of C-3 and the maximum segmental sagittal motion of C2-3 were determined. There was a significant increase in posterior displacement for the FM (1.9 +/- 1.2 mm, P: < 0.01), OETT (2.6 +/- 1.6 mm, P: < 0.0001), ETC (3.2 +/- 1.6 mm, P: < 0.0001), ILM-OETT (1.7 +/- 1.3 mm, P: < 0. 01), LMA (1.7 +/- 1.3 mm, P: < 0.01), FLEX-MAX (3.7 +/- 1.9 mm, P: < 0.0001), EXT-MAX (1.8 +/- 1.7, P: < 0.01), however, not for FOS-NETT (0.1 +/- 0.7 mm). Posterior displacement was less for the ILM-OETT and LMA than for the ETC (both P: < 0.04). There were no significant increases in segmental sagittal motion with any airway manipulation other than with FLEX-MAX (-4.5 +/- 4.0 degrees, P: < 0.01). Posterior displacement was similar to FLEX-MAX for the OETT and ETC; however, it was less for the FM, FOS-NETT, ILM-OETT, and LMA (all P: < 0.01). Posterior displacement was similar to EXT-MAX for all airway manipulations other than for FOS-NETT (P: < 0.001). For cervical motion and the techniques tested, the safest method of airway management in a patient with a posteriorly destabilized C-3 segment is FOS-NETT. LMA devices may be preferable to the ETC.

IMPLICATIONS

In the cadaver model of a destabilized third cervical vertebrae, significant displacement of the injured segment occurs during airway management with the face mask, laryngoscope-guided oral intubation, the esophageal tracheal Combitube (Kendall-Sheridan, Neustadt, Germany), the intubating and standard laryngeal mask airway; but not with fiberscope-guided nasal intubation. For cervical motion and the techniques tested, the safest airway technique with this injury is fiberscope-guided nasotracheal intubation. Laryngeal mask devices are preferable to the esophageal tracheal Combitube.

Segmental cervical spine motion during orotracheal intubation of the intact and injured spine with and without external stabilization

OBJECT

The purpose of this study was to establish a cadaveric model for evaluating cervical spine motion in both the intact and injured states and to examine the efficacy of commonly used stabilization techniques in limiting that motion.

METHODS

Intubation was performed in fresh human cadavers with intact cervical spines, following the creation of a C4-5 posterior ligamentous injury. Movement of the cervical spine during direct laryngoscopy and intubation was recorded using video fluoroscopy and examined under the following conditions: 1) without external stabilization; 2) with manual in-line cervical immobilization; and 3) with Gardner-Wells traction. Subsequently, segmental motion of the occiput through C-5 (Oc-C5) was measured from digitized frames of the recorded video fluoroscopy. The predominant motion, at all levels measured in the intact spine, was extension. The greatest degree of motion occurred at the atlantooccipital (Oc-C1) junction, followed by the C1-2 junction, with progressively less motion at each more caudal level. After posterior destabilization was induced, the predominant direction of motion at C4-5 changed from extension to flexion, but the degree of motion remained among the least of all levels measured. Traction limited but did not prevent motion at the Oc-C1 junction, but neither traction nor immobilization limited motion at the destabilized C4-5 level.

CONCLUSIONS

Cadaveric cervical spine motion accurately reflected previously reported motion in living, anesthetized patients. Traction was the most effective method of reducing motion at the occipitocervical junction, but none of the interventions significantly reduced movement at the subaxial site of injury. These findings should be considered when treating injured patients requiring orotracheal intubation.

The use of bedside fluoroscopy to evaluate the cervical spine in obtunded trauma patients

BACKGROUND

Recognition of a cervical spine injury is important to prevent further injury and in planning for future care. The management of the patient with a possible cervical spine injury who remains unresponsive is controversial.

METHODS

A retrospective evaluation of obtunded trauma patients admitted to the surgical intensive care unit who underwent bedside fluoroscopic cervical spine evaluation. Fluoroscopic findings and all complications were noted.

RESULTS

Twenty obtunded patients with possible cervical spine injuries underwent bedside fluoroscopic cervical spine evaluation. All patients had at minimum a normal three-view cervical spine series before fluoroscopy. Thirteen patients (65%) had the fluoroscopic examination completed at the bedside and were cleared. The complete cervical spine could not be evaluated in six patients (30%). One patient (5%) was found to have a C4-5 subluxation in the bedside examination. None of the patients had progression of their neurologic symptoms after cervical spine flexion/extension, and none developed evidence of spinal cord injury after being cleared during their hospital course. Cervical collars remained in place for 5.7+/-1.41 days (range, 1- 26 days). Three patients (15%) were noted to have decubiti under the cervical collar.

CONCLUSION

In this small study, the use of bedside fluoroscopy to evaluate the cervical spine appears safe and easy to perform. One unrecognized injury was identified. The technique is usually successful and gives reassurance that a significant cervical spine injury is not present.

Helmet and shoulder pad removal from a player with suspected cervical spine injury. A cadaveric model

STUDY DESIGN

Video fluoroscopy was used to evaluate the motion in an unstable spine during helmet and shoulder pad removal.

OBJECTIVE

To observe the amount of motion that occurs during the removal of helmet and shoulder pads in an injured spine.

SUMMARY OF BACKGROUND DATA

Removal of shoulder pads and helmet from a football player with suspected cervical spine injury can be particularly hazardous. How much flexion occurs at the unstable level during removal of equipment is unknown.

METHODS

Six fresh cadavers were used in the study. In three, an unstable C1-C2 segment was created by transoral osteotomy of the base of C2. In the remaining three, instability was created at C5-C6 by a posterior release. Under fluoroscopic recording, the helmets were removed by first removing the chin strap, face mask, and ear pieces. With the neck stabilized, the helmet was carefully removed. The shoulder pads were carefully removed, with the head stabilized. Angulation, distraction, and space available for the cord were measured at C1-C2. Translation, angulation, distraction, and change in disc height were measured in the specimens with unstable C5-C6.

RESULTS

In cadavers with C1-C2 instability, the mean change in angulation was 5.47 degrees, and space available for the cord was 3.91 mm. Shoulder pads were removed while the head was stabilized. The mean change in angulation at C1-C2 was less during removal of shoulder pads than during helmet removal at 2.9 degrees. Space available for the cord was 2.64 mm. Distraction was also greater during helmet removal (2.98 mm) than during shoulder pad removal (1.76 mm). In the unstable spine, the change in displacement in translation was greater during shoulder pad removal (3.87 mm), than during helmet removal (0.41 mm). Disc height change was similar. Distraction of the spinous processes was greater during helmet removal (3.68 mm) than during shoulder pad removal (1.37 mm). Angulation was similar in both maneuvers.

CONCLUSIONS

Helmet and shoulder pad removal in the unstable cervical spine is a complex maneuver. In the unstable C1-C2 segment, helmet removal causes more angulation in flexion, more distraction, and more narrowing of the space available for the cord. In the lower cervical spine (C5-C6), helmet removal causes flexion of 9.32 degrees, and during shoulder pad removal the neck extends 8.95 degrees, a total of approximately 18 degrees. Disc height changes from 1.24 mm of distraction to 1.06 mm of compression during helmet removal and shoulder pad removal for a total 2.3-mm change. Translation, which correlates with the change in the space available for the cord, is greater at C5-C6 during shoulder pad removal. Because most of the cadavers had C5 anteriorly displaced on C6 to begin with, the extension force during shoulder pad removal caused a 3.87-mm change in reduction of C5 on C6. Because of the motion observed in the unstable spine, helmet and shoulder pad removal should be performed in a carefully monitored setting. They should be removed together by at least three, preferably four, trained people.

Dynamic motion study of the whole lumbar spine by videofluoroscopy

STUDY DESIGN

Dynamic lumbar flexion-extension motion was assessed by videofluoroscopy.

OBJECTIVES

To identify the motion patterns of the whole lumbar spine in normal subjects and in patients with low back pain or spondylolisthesis during actual movement.

SUMMARY OF BACKGROUND DATA

Assessment of lumbar instability on terminal radiographs is controversial. Information regarding spinal kinematics during actual movement in vivo is scarce.

METHODS

Fluoroscopic lumbar sagittal motion videos were recorded in volunteers (n = 13; mean age, 22.3) and in patients with chronic low back pain (n = 8; mean age, 43.5) and degenerative spondylolisthesis (n = 8; mean age, 63.1) while the subjects bent forward from a standing neutral position (eccentric motion) and then returned to the original position (concentric motion). The videos recorded approximately 8 seconds of motion and were converted to still images at 5 frames per second. Disc angles from the horizontal line were measured to estimate sagittal rotation of each segment. Disc degeneration was evaluated on T2-weighted midsagittal magnetic resonance image.

RESULTS

In the volunteer group, six exhibited sequentially spreading motion, four exhibited simultaneous motion, and three showed an altered motion-spreading pattern in the eccentric phase. The first two patterns were considered normal. Six (67%) of the patients with chronic low back pain also showed normal patterns, but seven (88%) of the patients with degenerative spondylolisthesis showed disordered patterns. The order of motion in the concentric phase was also different among the three groups. Prolonged deflection of the slipped segment was observed more frequently in the patients with degenerative spondylolisthesis. Disc degeneration was not always associated with motion-spreading order and the motion patterns.

CONCLUSION

Segmental instability influences the whole lumbar motion in patients with degenerative spondylolisthesis. The patients with chronic low back pain did not show a significant difference when compared with the volunteers.

The intubating laryngeal mask. Use in failed and difficult intubation

The use of the intubating laryngeal mask in three patients is described. In two patients for whom tracheal intubation using traditional techniques had failed, the intubating laryngeal mask was used to achieve successful tracheal intubation. The trachea of one of these patients was subsequently re-intubated for a second procedure using the same technique. A third patient with a cervical spine fracture whose trachea was electively intubated using the intubating laryngeal mask is also presented.

The effect of airway maneuvers on the unstable C1-C2 segment. A cadaver study

STUDY DESIGN

This is a cadaver study in which video fluoroscopy is used to measure motion of the unstable spine at C1-C2 during intubation maneuvers.

OBJECTIVES

To quantify the amount of motion that occurs at an unstable C1-C2 spinal segment during the use of various intubation techniques using a cadaver model.

SUMMARY OF BACKGROUND DATA

In previous work by the authors, a methodology and measurements for the unstable C5-C6 segment in a cadaver model were developed. These studies showed that the most motion was created by a chin lift and jaw thrust and that oral techniques created more motion than nasal intubation. The potential motion that occurs during intubation with instability at C1-C2 is yet unstudied. Therefore, a study to determine the effects of intubation on the spine with an unstable C1-C2 segment was designed.

METHODS

Six human cadavers were used for the study. Measurements before and after transoral osteotomy of the odontoid were performed using video fluoroscopy. Pre-intubation maneuvers and oral and nasal intubation were studied.

RESULTS

Oral intubation and nasal intubation caused similar diminution of space available for the cord. Chin lift and jaw thrust caused a larger diminution of space available for the cord than either nasal or oral intubation techniques.

CONCLUSIONS

Although nasal intubation is the accepted procedure for intubation of the unstable spine, nasal and oral intubation seemed to have the same ability to narrow the space available for the cord in the model in this study. Great care should be taken while performing the chin lift/jaw thrust maneuvers in preparation for intubation, because these pre-intubation techniques caused the most motion and hence narrowed the space available for the cord in the unstable cervical spine.