| BACKGROUND: Most studies concerning the effect of a chiropractic spinal adjustment on blood pressure have shown either no significant effect of the adjustment or no conclusive relationship between the level of the spinal adjustment and the nature of the blood pressure changes. This paper presents the results of a pilot study that investigates the effect of a diversified spinal adjustment on blood pressure with respect to the region of the spine adjusted. METHODS: Participants that met the selection criteria of the study included 63 patients reporting to a private chiropractic practice in Auckland, New Zealand. Informed consent was obtained before the patients were included in the study and the study gained ethics approval from the New Zealand College of Chiropractic Ethics Committee. Blood pressure was manually recorded from both arms in the sitting position after patients were allowed five minutes of quiet relaxation. Patients were then examined for the presence of vertebral subluxations using motion and static palpatory findings and a coin was tossed to determine the allocation of the patient to the control or experimental group for that trial. In the experimental group, an adjustment was performed in each trial based on motion and static palpation findings and the trial was then allocated to a subgroup depending on the region of the spine that was adjusted. The control group received only gentle digital pressure at the site of suspected vertebral subluxation. The subgroup sizes ranged from 36-46 trials. Blood pressure was retaken at the end of each trial by the same chiropractor who performed the adjustment or digital pressure and the initial recording. RESULTS: The ‘pre’ and ‘post’ blood pressure recordings were compared using a 2-tailed paired t-test. The experimental subgroups all showed statistically significant changes of systolic and diastolic blood pressure (p<0.001). The cervical and lumbosacral adjustment groups showed a decrease of both systolic and diastolic pressure, while the thoracic adjustment group showed an increase. In the control groups, the only statistically significant change following adjustment setup and gentle digital pressure was for the diastolic pressure of the cervical group, which showed a small decrease (p=0.02). DISCUSSION: The results of the present study support previous assertions that a sympathetic excitatory response may occur after adjustments to the thoracic spine and a sympathetic inhibitory response after adjustments to the lumbosacral and cervical spine. It is likely that considerable integration occurs at both spinal segmental and supraspinal levels of the neuraxis as a consequence of parallel processing of primary afferent inputs. Varying degrees of activation and inhibition of both segmental and supraspinal pathways may contribute to the different blood pressure responses depending on the region that was adjusted. Clinically, it is not known how important the results of this study are as blood pressure was not monitored long-term. Experimental design should be enhanced in future studies by using a blinded examiner, considering longer term follow up and the use of a digital oscillometric sphygmomanometer to record blood pressure. This abstract is reproduced with the permission of the publisher. |
