Spinal anaesthesia with hyperbaric tetracaine: effect of age and body mass.

To discover the influence of age and body mass on spinal analgesia with hyperbaric tetracaine, 60 patients (17-82 years) were administered a subarachnoid injection of 15 mg tetracaine in 3 ml of 5% glucose. The patients were in the lateral position during the injection and in the supine position thereafter. The maximal spread of analgesia (mean T4, range T1-T11) did not correlate with age or body mass. Any variable studied was not significantly different for the different age groups. In 29 patients (48%) the block required supplementation with fentanyl or general anaesthesia (five patients). Tourniquet-induced pain occurred in eight patients (28% of patients with tourniquet). Decreases in systolic arterial blood pressure, greater than 30% of the preanaesthetic value, correlated with the level of analgesia and were more frequent in patients over 50 years (P less than 0.01). Severe hypotension and bradycardia with transient serious changes in QRS-complexes occurred in one patient (analgesia level, T3). In conclusion, 15 mg of hyperbaric tetracaine provided a relatively high sensory spinal blockade without correlating with age or body mass. Supplementation of analgesia during surgery was needed in almost half of the patient material.