Effects of spinal immobilization at 20° on end-tidal carbon dioxide

The aim was to determine the effect on end-tidal carbon dioxide (ETCO₂) of spinal immobilization (SI) at a conventional 0° angle and to investigate the usefulness of immobilization at a 20° angle for preventing possible hypoventilation.

The study included 80 healthy volunteers, randomly divided into two groups. Spinal backboards and cervical collars were applied in Group 1 using a 0° angle and in Group 2 using a 20° angle, with the head up. SI was continued for 1 h, and ETCO₂ values were measured at the 0th, 30th and 60th minute.

There were no significant differences between the groups in 0th and 30th minute ETCO₂. However, after 60th minute, results showed a statistically significant increase in ETCO₂ in Group 1 (35.5 mmHg [IQR 25-75:35-38]) compared to Group 2 (34 mmHg [IQR 25-75:33-36]) (p < 0.001). During SI, there was a statistically significant increase in ETCO₂ in Group 1 (35 mmHg [IQR 25-75:34-36], 35.5 mmHg [IQR 25-75:34-37] and 36 mmHg [IQR 25-75:35-38] respectively at the 0th, 30th and 60th minute after SI) (p < 0.001) and no change in Group 2. Also, we found statistically significant differences between ΔETCO₂ levels in Groups 1 and 2 at all 3 time intervals.

Conventional SI with an angle of 0° led to an increase in ETCO₂ while subjects immobilization at a 20° angle maintained their initial ETCO₂ values. Immobilization at 20° may prevent decompensation in patients who have thoracic trauma or lung diseases or those who are elderly, pregnant, or obese.