Spinal Cord Injury
Many authors recommend awake fiberoptic intubation as a safe alternative to DL in patients with cervical cord injuries – Schwartz et. al reported a series of 327 patients with cervical lesions who received nasal/oral fiberoptic intubation with 100% success rate. In 12 patients (3.6%), anatomic abnormalities transnasal endotracheal intubation and oral fiberoptic intubation was required. The minimal peripheral oxygen saturation during intubation exceeded 90% in 289 patients (88%). In the other 38 patients, the mean O2 saturation was 84.2+/-4.3% (range, 72-89%). Cervical stabilizers did not have to be removed for intubation in any patient. None of the patients had postoperative neurologic deficits attributable to the intubation procedure [Schwarz G et. al. J Neurosurg Anesthesiol. 11:11, 1999]. Other authors feel that routine fiberoptic intubation is overkill and claim that there is no evidence of improved outcome [McLeod et. al. Br J Anaesth 84: 705, 2000]
Goal is to reduce the incidence of secondary injuries, thus stabilization is key. Beware of spinal shock (loss of sympathetic innervation) in these patients, and treat with fluids, vasopressors if needed, and atropine if cardiac accelerator nerves [T1-T4] are affected. NG tube and bladder catheterization are required if the lesion affects either the GI tract or the bladder. Spinal cord injury patients are prone to heat loss because they cannot vasoconstrict
SCh is commonly avoided in spinal cord injury patients, although it is likely safe if given within 24 hours of injury [Stoelting RK. Basics of Anesthesia, 5th ed. Elsevier (China) p. 461, 2007].
Keep in mind that these patients often have reduced anesthetic requirements because they may have reduced or no sensation at the surgical site. Neurologic injury also predisposes them to decreased sympathetic tone and subsequent hypotension
The most fearsome complication of anesthesia in the chronic spinal cord injury patient is autonomic hyperreflexia, which results in hypertension and bradycardia (most commonly associated with a T6 lesion – surgical stimulation can produce SNS activity that leads to vasoconstriction below the leel of transection) – consider spinal anesthesia in these patients as it is generally effective at reducing autonomic hyperreflexia [Stoelting RK. Basics of Anesthesia, 5th ed. Elsevier (China) p. 462, 2007]
Anesthesia Key Points
Anesthesia Key Points – Protect an unstable spine during transport and intubation (consider fiberoptic, inline stabilization, data equivocal) – Beware of spinal shock and/or severe bradycardia (T1-4 cardioaccelerators) – SCh likely safe within 24 hours of injury – Reduced anesthetic requirements if surgery site distal to injury – Chronic patient: CONSIDER SPINAL ANESTHESIA (to avoid hyperreflexia)
Medical / Physiologic Considerations
An abundance of laboratory data suggests that elevating blood pressure improves blood flood to the spinal cord [Surg Neurol 10 71: 1978; Surg Neurol 10: 64, 1978; Surg Neurol 10: 63, 1978; J Trauma 28: 481, 1988], but so far no study has demonstrated benefit in human subjects. It is, however, generally accepted that SBP should be kept > 90 mm Hg
Early on, SCI patients should receive an NG tube due to aspiration/gastric atony [Spine 6: 538, 1981]. Additionally, these patients require stress ulcer prophylaxis – there are no trials which show a significant difference in outcomes between PPI and H2 blockers in this population
Initially after SCI, the bladder is hypotonic. Lesions proximal to the sacral cord ultimately produce a hypertonic bladder. Poor coordination between the detrussor muscle and the urinary sphincter results in incomplete emptying and progressively increasing urinary volumes
SCI patients can develop pressure ulcers in less than 6 hours on a rigid spine board [Arch PMR 74: 248, 1993; Arch PMR 81: 506. 2000]
Normally occurs with stimulation (including bladder or bowel dysfunction) below the lesion (pressure stimuli above the lesion do not usually change blood pressure). AD is an autonomic reflex which causes a sharp rise in blood pressure, reduced flow to the periphery, combined with flushing and sweating above the lesion as well as bradycardia. The hypertensive component of AD may be caused by a supersensitivity of adrenoreceptors, and, of note, blood pressure in quadriplegic patients may increase 5- to 10-fold in response to the exogenous administration of angiotensin and to catecholamines. Sensitivity is rarely increased when the lesion is below T5. There is apparently a normal level of adrenoreceptors in these patients, even those with long-standing quadriplegia.
Elective Spine Surgery
Prone cases require extra care with regards to securing the endotracheal tube as well as padding. Scoliosis surgery can be accompanied by significant blood loss, thus the anesthesiologist should consider using a Cell Saver (if one believes it spares allogenic transfusions, which, according to CABG data, it does not). Scoliosis surgery is accompanied by a 1-4% incidence of postoperative neurologic complications.