Effect of spinal immobilization on heart rate, blood pressure and respiratory rate

Vital signs remain important clinical indicators in the management of trauma. Tissue injury and ischemia cause tachycardia and hypertension, which are mediated via the sympathetic nervous system (SNS). Spinal immobilization is known to cause discomfort, and it is not known how this might influence the SNS and contribute to abnormal vital signs. Hypothesis This study aimed to establish whether the pain and discomfort associated with spinal immobilization and the maneuvers commonly used in injured patients (eg, log roll) affect the Heart rate (HR), Systolic Blood Pressure (SBP) and Respiratory rate (RR). The null hypothesis was that there are no effects.

A prospective, unblinded, repeated-measure study of 53 healthy subjects was used to test the null hypothesis. Heart rate, BP and RR were measured at rest (five minutes), after spinal immobilization (10 minutes), following log roll, with partial immobilization (10 minutes) and again at rest (five minutes). A visual analog scale (VAS) for both pain and discomfort were also collected at each stage. Results were statistically compared.

Pain VAS increased significantly during spinal immobilization (3.8 mm, P < .01). Discomfort VAS increased significantly during spinal immobilization, after log roll and during partial immobilization (17.7 mm, 5.8 mm and 8.9 mm, respectively; P < .001). Vital signs however, showed no clinically relevant changes. Discussion Spinal immobilization does not cause a change in vital signs despite a significant increase in pain and discomfort. Since no relationship appears to exist between immobilization and abnormal vital signs, abnormal vital signs in a clinical situation should not be considered to be the result of immobilization. Likewise, pain and discomfort in immobilized patients should not be disregarded due to lack of changes in vital signs.