Guided breathing exercise modulates blood pressure for people with spinal cord injury

BACKGROUND People with Spinal Cord Injury (SCI) often suffer from autonomic dysfunction, including orthostatic intolerance. These effects can be similar to those that astronauts experience while exposed to microgravity. To improve post-flight orthostatic intolerance, and other symptoms of autonomic dysfunction, scientists at NASA designed a biofeedback protocol, Autogenic Feedback Training Exercise (AFTE). AFTE combines specific autogenic exercises (e.g., self-suggestion of warmth in the hands) with biofeedback of multiple physiological responses (i.e., blood pressure [BP], heart rate, body temperature, breathing rate). We modified this protocol by adding guided breathing exercises and immersive virtual reality (VR) and tested it among people with and without SCI. The study aims to determine if AFTE is viable for improving autonomic dysfunction in individuals with SCI. We hypothesize that participants with SCI will improve symptoms of orthostatic hypotension and be able to modulate BP toward normotensive values after eight sessions of AFTE. METHODS/DESIGN A convenience sample of five (n=5) participants with chronic cervical SCI: two women (body weight 90+/−13Kg, height 164+/−2Cm, age 48+/−18), three men (body weight 96+/−37, height 180+/−5Kg, age 40+/−28) and four (n=4) participants without SCI: two women (body weight 57+/−9 Kg, height 164+/ 9 Cm, age 22+/−1) and two men (body weight 78 Kg +/−18, height 182 cm +/−5, age 27+/−2) participated in the study. Training consisted of eight 3-minute cycles of alternating relaxing then stimulating breathing, interoception (i.e., noticing inner body sensation), and VR. The relaxing breathing to lower BP consisted of making the “mmm” sound with three long nasal exhales to lower blood pressure. The stimulating breathing to raise BP consisted of three series of ten quick nasal exhales. After each of the eight cycles, participants were given feedback on whether they met their goal of increasing of decreasing MAP 5 mmHg during stimulation or relaxation cycles respectively. Training was performed twice a week for five weeks. RESULTS Participants successfully modulated their BP during the breathing exercise portion of the training. Participants reported they were able to use the technique at home after training was completed. CONCLUSIONS Guided breathing exercises could provide a readily available method of BP modification without side effects, potentially enabling more exercise compliance for people with SCI.