Cardiovascular and Hormonal Responses to Food Ingestion

Persons with chronic primary autonomic failure and widespread sympathetic denervation and postural hypotension often have postprandial hypotension (Mathias 1991). Food consumption often exacerbates symptoms and the degree of postural hypotension in certain groups. The cardiovascular responses to food ingestion in individuals with tetraplegia have been investigated.

Discussion

A fall in BP following the ingestion of food has been described in individuals with secondary autonomic failure of various causes. A single study has assessed cardiovascular and hormonal responses to food ingestion among individuals with tetraplegia from cervical spinal cord transection. Baliga et al. (1997) investigated the effects of a standard liquid meal (300 mL total liquid volume, 550 kilocalories, 66 grams carbohydrate, 22 grams fat, 18 grams protein) on BP, HR and neurohormonal levels. Five individuals with paraplegia with complete lesions (T12-L3) and essentially intact sympathetic nervous systems who did not experience postural hypotension served as the control group. The experimental group consisted of six individuals with tetraplegia (C4-7) with chronic and complete cervical spinal cord transection. All had postural hypotension. After food ingestion there was no change in BP or HR in either group. Plasma noradrenaline was unchanged for those with tetraplegia but rose in those with paraplegia. Conversely, plasma renin activity rose among those with tetraplegia but not paraplegia.

Conclusion

There is level 2 evidence (from one prospective controlled trial: Baliga et al. 1997) that consumption of a standard liquid meal does not change blood pressure, heart rate or noradrenalin levels in individuals with tetraplegia and postural hypotension.