What is the proper technique for manual in-line stabilization during intubation of a patient with a spinal cord injury?

Manual In-Line Stabilization Technique for Intubation in Spinal Cord Injury

Apply manual in-line stabilization (MILS) during intubation by having an assistant position themselves at the patient's head, placing their hands on both sides of the patient's head and neck to maintain the cervical spine in a neutral position without applying traction, while simultaneously removing the anterior portion of the cervical collar to improve mouth opening and glottic visualization. 1

Specific Technique for MILS Application

Positioning and Hand Placement

• The assistant stands at the head of the bed, placing one hand on each side of the patient's head and mastoid processes 1, 2
• Maintain the cervical spine in neutral alignment without applying any traction or distraction forces, as traction causes clinically significant distraction and must be avoided 3
• The goal is to prevent flexion, extension, and rotation of the cervical spine during airway manipulation 1

Cervical Collar Management

• Remove the anterior portion of the cervical collar before intubation attempts while maintaining MILS 1, 4, 2, 5
• This removal facilitates mouth opening and significantly improves glottic exposure, which is critical since MILS alone increases the rate of difficult intubations 1
• Keep the posterior portion of the collar in place to provide some baseline stability 4, 2

Intubation Approach with MILS

Recommended Technique

• Use rapid sequence induction with direct laryngoscopy and a gum elastic bougie without Sellick maneuver 1, 2, 5
• Avoid Sellick maneuver entirely as it increases cervical spine movement 1, 2, 5
• The gum elastic bougie facilitates successful first-attempt intubation even with suboptimal glottic views 1

Laryngoscopy Considerations

• MILS significantly worsens laryngoscopic view, with the majority of patients demonstrating Modified Cormack-Lehane Grade 3a or 3b views when MILS is applied 6
• Consider applying backward-upward-rightward pressure (BURP) if needed, as this significantly improves the view compared to MILS alone 6
• Videolaryngoscopy may be considered as an alternative, though in the prehospital setting it cannot be recommended as first-line based on prospective data 1
• The operator's experience with the chosen device is paramount—use the technique with which you are most proficient 1, 7

Critical Evidence and Rationale

Why MILS is Recommended Despite Limitations

• Historical series demonstrate major reduction in complications with MILS application, even though the level of evidence is low 1
• MILS is recommended during both mask ventilation and orotracheal intubation to limit cervical spine mobilization 1
• However, MILS does not effectively immobilize the cervical spine and increases the likelihood of difficult and failed intubation 7

Actual Risk of Neurological Injury

• The risk of spinal cord injury during intubation appears minimal even with gross cervical spine instability 7
• All airway interventions cause some cervical spine movement, but whether these movements are clinically significant in terms of spinal cord impingement remains unclear 7
• Studies on cadavers with type-2 odontoid fractures show that the space available for the spinal cord is preserved during laryngoscopy and intubation with MILS 8
• Only a few published case reports suggest possible neurological aggravation related to intubation 1

Common Pitfalls to Avoid

Traction Application

• Never apply traction to the cervical spine during MILS—the goal is stabilization in neutral position, not distraction 3
• Traction causes clinically significant distraction and should be completely avoided 3

Collar Management Errors

• Do not attempt intubation with the anterior cervical collar in place, as this severely limits mouth opening and worsens glottic visualization 1
• Failure to remove the anterior collar is a common error that significantly increases intubation difficulty 4, 2

Technique Selection

• Do not delay intubation attempting unfamiliar techniques—choose the method with which you have the most proficiency 1, 7
• All patients requiring MILS should be considered difficult airways and preparation should be made accordingly 6
• Have backup airway equipment immediately available given the increased difficulty associated with MILS 6

Hemodynamic Considerations

• Maintain systolic blood pressure >110 mmHg before and during intubation to reduce mortality 1, 4, 2, 5
• Target mean arterial pressure of 85-90 mmHg in the post-intubation period 2, 5