Outline the respiratory and cardiovascular consequences of an acute complete spinal cord transection at C6.
The main respiratory consequences of an acute C6 transection include the effects on the
inspiratory muscles, the expiratory muscles, lung volumes, effects of changes in posture and
effects on gas exchange. Sparing of the phrenic nerve, the main muscle of inspiration (C3 -
5), but paralysis of the external intercostal muscles innervated by thoracic nerve roots
results in paradoxical inward movement of the chest wall on inspiration. Paralysis of all the
expiratory muscles including the internal intercostal muscles innervated by thoracic nerve
roots and the abdominal wall muscles, which are innervated by lower thoric and lumbar
nerves. Many candidates did not mention these muscles or their innervation in their
answers. While expiration is normally passive these muscles are required for manoeuvres
involving forced exhalation like coughing. Forced expiratory lung volumes (FEV1 and FVC)
are reduced. Work of breathing is increased. Static lung volumes reveal a restrictive lung
defect with most lung volumes decreased but in particular expiratory reserve volume (ERV)
is significantly reduced. The reduction in FRC leads to airway closure, atelectasis and
pathologic low V/Q and shunt and hence hypoxemia. These mechanisms can result in
significant hypoxemia but were not described by many candidates. The second part of the
question concerning the cardiovascular consequences of C6 transection was better
answered. Areas that required mention in this section included the early massive
sympathetic outflow and hypertension via the release of catecholamines from the adrenal
medulla. Neurogenic shock is also seen due to interruption of the sympathetic outflow and
impaired reflex vasoconstriction secondary to hypotension of any cause. Finally the loss of
sympathetic innervation of the heart (T1-T4) results in unopposed parasympathetic cardiac
stimulation and bradycardia and bradyarrthymias.
A quick answer in point form would look like this:
Respiratory consequences
Cardiovascular consequences
Cardozo, Christopher P. "Respiratory complications of spinal cord injury." The journal of spinal cord medicine 30.4 (2007): 307.
Freeman, L. Willard. "The metabolism of calcium in patients with spinal cord injuries." Annals of surgery 129.2 (1949): 177.
Baydur, Ahmet, Rodney H. Adkins, and Joseph Milic-Emili. "Lung mechanics in individuals with spinal cord injury: effects of injury level and posture." Journal of applied Physiology 90.2 (2001): 405-411.
Teasell, Robert W., et al. "Cardiovascular consequences of loss of supraspinal control of the sympathetic nervous system after spinal cord injury." Archives of physical medicine and rehabilitation 81.4 (2000): 506-516.
Claus-Walker, J., and L. S. Halstead. "Metabolic and endocrine changes in spinal cord injury: I. The nervous system before and after transection of the spinal cord." Archives of physical medicine and rehabilitation 62.12 (1981): 595-601.
Claus-Walker, J., and L. S. Halstead. "Metabolic and endocrine changes in spinal cord injury: II (section 1). Consequences of partial decentralization of the autonomic nervous system." Archives of physical medicine and rehabilitation63.11 (1982): 569-575.
Claus-Walker, J., and L. S. Halstead. "Metabolic and endocrine changes in spinal cord injury: II (section 2). Partial decentralization of the autonomic nervous system." Archives of physical medicine and rehabilitation 63.11 (1982): 576-580.
Claus-Walker, J., and L. S. Halstead. "Metabolic and endocrine changes in spinal cord injury: III. Less quanta of sensory input plus bedrest and illness."Archives of physical medicine and rehabilitation 63.12 (1982): 628-631.
Claus-Walker, J., and L. S. Halstead. "Metabolic and endocrine changes in spinal cord injury: IV. Compounded neurologic dysfunctions." Archives of physical medicine and rehabilitation 63.12 (1982): 632-638.
GORE, RICHARD M., RICHARD A. MINTZER, and LEONID CALENOFF. "Gastrointestinal complications of spinal cord injury." Spine 6.6 (1981): 538-544.
Ebert, Ellen. "Gastrointestinal involvement in spinal cord injury: a clinical perspective." Journal of Gastrointestinal & Liver Diseases 21.1 (2012).
Tong, M., and G. M. Holmes. "Gastric dysreflexia after acute experimental spinal cord injury in rats." Neurogastroenterology & Motility 21.2 (2009): 197-206.
Gondim, F. A. A., G. R. De Oliveira, and F. P. Thomas. "Upper gastrointestinal motility changes following spinal cord injury." Neurogastroenterology & Motility22.1 (2010): 2-6.
Berk, Robert N., and David B. Coulson. "The body cast syndrome." Radiology94.2 (1970): 303.
Kennedy, R. H., and M. J. Cooper. "An unusually severe case of the cast syndrome." Postgraduate medical journal 59.694 (1983): 539-540.
Kewalramani, L. S. "Neurogenic gastroduodenal ulceration and bleeding associated with spinal cord injuries." Journal of Trauma-Injury, Infection, and Critical Care 19.4 (1979): 259-265.
Anwar, Fahim, et al. "Gastrointestinal bleeding in spinal injuries patient: Is prophylaxis essential?." British Journal of Medical Practitioners 6.1 (2013).
Lin, Vernon W., et al. "Temperature Regulation in Spinal Cord Disease." (2003). Spinal Cord Medicine: Principles and Practice. Demos Medical Publishing, Inc.
Hambly, P. R., and B. Martin. "Anaesthesia for chronic spinal cord lesions."Anaesthesia 53.3 (1998): 273-289.
TOBEY, RAYMOND E. "Paraplegia, succinylcholine and cardiac arrest."Anesthesiology 32.4 (1970): 359-363.