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

[Cervical spine instability in the surgical patient]

Many congenital and acquired diseases, including trauma, may result in cervical spine instability. Given that airway management is closely related to the movement of the cervical spine, it is important that the anesthesiologist has detailed knowledge of the anatomy, the mechanisms of cervical spine instability, and of the effects that the different airway maneuvers have on the cervical spine. We first review the normal anatomy and biomechanics of the cervical spine in the context of airway management and the concept of cervical spine instability. In the second part, we review the protocols for the management of cervical spine instability in trauma victims and some of the airway management options for these patients.

Pediatric transtracheal and cricothyrotomy airway devices for emergency use: which are appropriate for infants and children?

Cricothyrotomy or insertion of a transtracheal device is a life-saving maneuver that may be performed on an emergent or semi-elective basis as a means of bypassing an obstructed upper airway. A surgeon is trained to perform this life-saving procedure whereas most anesthesiologists are not facile with the scalpel. It is for this reason that many percutaneous devices have been developed for use by surgeons and nonsurgeons alike. Unfortunately, the majority of such devices are designed for use in adults and/or teenagers but are not appropriate for neonates and infants. The unique anatomy of the infant larynx, the small size of the cricothyroid membrane, and the technical difficulty of locating the correct anatomical structures make the use of most of these devices impractical if not outright dangerous in neonates and infants. This paper will review many (but not all) of the available devices, associated literature, pitfalls and dangers. It is emphasized that each clinician should become familiar with the advantages and disadvantages of these devices and obtain training with simulators or animal models. A strategy for management of the 'cannot ventilate, cannot oxygenate, cannot intubate' situation should be developed with age and size appropriate equipment.

A cervical spine model to predict injury scenarios and clinical instability

A complete and detailed three-dimensional finite element model of the human cervical spine (C1-C7), including soft and hard tissues, was created using a digitized geometric measurement tool. The model was validated against existing experimental studies in flexion, extension, lateral bending, and axial rotation. The aims of this study were to use the model to simulate the mechanisms of injury scenarios, such as diving and football accidents, and to correlate the external and internal responses of the spinal components to disc herniation and clinical instability. It was determined that a shear-generated flexion moment of about 10 Nm or a compression-flexion load of 450 N would generate significant stresses and strains in the discs, together with sufficient posterior-anterior displacement and rotational angulation of the vertebrae, to place the mid and lower cervical spine at risk of clinical instability or disc herniation. The results revealed that the location of the maximum stresses in the discs could not be directly correlated with the type of loads. In addition, for the loadings considered, the maximum displacement of the spine could be reduced by as much as 50% when the restraint of the cervical spine is changed from a C7-T1 to C7-T1 and C1-C2 fixed conditions.

Considerations for airway management for cervical spine surgery in adults

Surgery on the cervical spine runs the gamut from minor interventions done in a minimally invasive fashion on a short-stay or ambulatory basis, to major surgical undertakings of a high-risk, high-threat nature done to stabilize a degraded skeletal structure to preserve and protect neural elements. Planning for optimum airway management and anesthesia care is facilitated by an appreciation of the disease processes that affect the cervical spine and their biomechanical implications and an understanding of the imaging and operative techniques used to evaluate and treat these conditions. This article provides background information and evidence to allow the anesthesia practitioner to develop a conceptual framework within which to develop strategies for care when a patient is presented for surgery on the cervical spine.

Airway Management in Trauma: An Update

This article reviews the more recent theoretic and practical information that pertains to airway management in the trauma setting. This is followed by a presentation of the newer airway devices that may be advantageous in the management of the airway in trauma as well as a discussion of other devices, techniques, or maneuvers that are useful in the trauma setting but may be underused. Each clinician needs to be knowledgeable about the various airway options and then, based on one's own particular skills and resources, construct an airway management algorithm that works best for him or her. Each clinician needs to be knowledgeable about the various airway options, and then, based on the clinician's particular skills and resources, construct an airway management algorithm that works best.

Cervical spine motion: a fluoroscopic comparison of Shikani Optical Stylet® vs Macintosh laryngoscope

PURPOSE

The optimal technique to manage the airway in patients presenting with a potential or documented cervical spine (C-spine) injury remains unresolved. Using fluoroscopic video assessment, C-spine motion during laryngoscopy with a Shikani Optical Stylet (SOS) was compared to C-spine motion during intubation using a Macintosh blade.

METHODS

Twenty-four healthy surgical patients gave written consent to participate in a crossover randomized controlled trial; all patients were subjected to both Macintosh and Shikani laryngoscopy with manual inline stabilization following induction of anesthesia. The C-spine motion was examined at four areas: the occiput-C1 junction, C1-C2 junction, C2-C5 motion segment, and C5-thoracic motion segment. The time required for laryngoscopy was also measured (duration > 120 sec was deemed a failure of the laryngoscopy technique).

RESULTS

On average, C-spine motion was 52% less (P < 0.02) at three of the motion segments studied, occiput-C1, C2-C5, and C5-thoracic when comparing SOS vs Macintosh laryngoscopy. There was no difference between techniques at the C1-C2 segment. Laryngoscopy with SOS (28 +/- 17 sec) took longer than with Macintosh blade (17 +/- 7 sec), P < 0.01. There were two failures out of 23 using the SOS, vs none with the Macintosh blade.

CONCLUSION

For patients in whom C-spine movement is undesirable, use of the SOS may limit neck movement, while modestly increasing the time required to intubate, and/or the risk of procedure failure.

Educating Anesthesiology Residents to Perform Percutaneous Cricothyrotomy, Retrograde Intubation, and Fiberoptic Bronchoscopy Using Preserved Cadavers

Experience with invasive airway procedures may be difficult to obtain during residency training, and anesthesiologists may therefore be hesitant to use these life-saving techniques. We designed a prospective study to determine whether using embalmed cadavers to teach percutaneous cricothyrotomy (PC), retrograde intubation (RI), and fiberoptic intubation to anesthesiology residents would improve their perceived procedural confidence and ability. After demonstration of these techniques by experienced attending physicians, residents were allowed to practice, with instructor guidance, on the cadavers. Residents completed surveys before and after the workshop about their perceived confidence using these techniques. Eighteen residents attended the lecture workshop and completed surveys. The number of residents who reported that they would use PC increased from 0% to 78% (P <or= 0.001) and those who reported they could correctly perform PC technique increased from 17% to 94% (P <or= 0.001). Likewise, the number of residents who reported they would use RI increased from 6% to 67% (P <or= 0.001) and those who reported they could correctly perform RI technique increased from 28% to 83% (P <or= 0.001). There were no significant changes in residents' confidence with fiberoptic intubation. The results of this study demonstrate an improvement in the confidence of anesthesiology residents in performing PC and RI after training using embalmed cadavers.

Surgical approach in difficult airway management

In all difficult airway algorithms, cricothyroidotomy is the life-saving procedure and is the final 'cannot ventilate, cannot intubate' option, whether in pre-hospital, emergency department, intensive care unit, or operating room patients. Cricothyroidotomy is a relatively safe and rapid means of securing an emergency airway. As with all other critical procedures in emergency medicine, a thorough knowledge of the technique and adequate practice prior to attempting to perform an emergency cricothyroidotomy are essential.

Emergency care in facial trauma--a maxillofacial and ophthalmic perspective

Facial trauma, with or without life- and sight-threatening complications, may arise following isolated injury, or it may be associated with significant injuries elsewhere. Assessment needs to be both systematic and repeated, with the establishment of clearly stated priorities in overall care. Although the American College of Surgeons Advanced Trauma Life Support (ATLS) system of care is generally accepted as the gold standard in trauma care, it has potential pitfalls when managing maxillofacial injuries, which are discussed. Management of facial trauma can arguably be regarded as "facial orthopaedics", as both specialities share common management principles. This review outlines a working approach to the identification and management of life- and sight-threatening conditions following significant facial trauma.

Invasive Techniken in der Notfallmedizin

Cricothyrotomy is a very invasive technique to secure the airway in an emergency but is irreplacable when less invasive techniques fail or cannot be instigated under the prevailing circumstances. Various techniques have been reported which can be subdivided into anatomical-surgical preparation or puncture techniques. The preferred strategy is mostly oriented towards the departmental standard procedure which will be decided by the clinical situation. Training for each procedure can be carried out in intensive care departments, and using autopsy material or a manekin. Various methods of cricothyrotomy will be discussed here, and additionally an anatomical preparation and two puncture techniques will be demonstrated in detail.

Airway management after upper cervical spine injury: what have we learned?

PURPOSE

Survival after atlanto-axial-occipital ligamentous injury is uncommon and experience with the immediate clinical management of these patients is similarly low. There has been considerable work published recently with respect to airway management in similar patients and a review of this material was undertaken.

METHODS

Medline searches were performed to seek out the English language literature using the key words and phrases: cervical spinal injury; atlanto-occipital dislocation; atlanto-occipital disarticulation; and airway management after spinal injury. The titles were culled for materials relevant particularly to upper cervical spinal injury, these were obtained and reviewed. The bibliographies of these articles were searched to ensure that the review would be complete.

RELEVANT FINDINGS

The majority of cervical spinal movement occurring during direct laryngoscopy is concentrated in the upper cervical spine. The magnitude of movement during airway management rarely exceeds the physiological limits of the spine. Movement is reduced by in-line immobilization but traction forces cause clinically important distraction and should be avoided. Indirect techniques for tracheal intubation cause less cervical movement than does the direct laryngoscope. Survival after severe upper ligamentous injury is uncommon but intact survival occurs. Missed diagnosis is common and associated with a high incidence of severe secondary injury. Failure to immobilize the spine is deemed to be the most relevant factor in secondary injury.

CONCLUSIONS

Patients who survive severe upper cervical ligamentous injury and present to hospital are uncommon. However, of those who do, both intact survival and survival with limited neurological sequelae do occur. Meticulous airway care with maintenance of alignment and provision of continuous cervical immobilization are an integral component of care in these patients.

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.