Analgesic and Respiratory Effects of Epidural Sufentanil in Patients Following Thoracotomy

Abstract

Immediately following thoracotomy, 22 patients were entered into a randomized, double blind study comparing the effects of three lumbar epidural doses of sufentanil on postoperative pain and respiratory pattern. Patients were given either 30 μg (group I), 50 μg (group II), or 75 μg (group III) of epidural sufentanil in 20 ml N saline. Repeat doses were given on request for the 24-h study period. Linear analogue pain score (PS), heart rate (HR), and mean arterial pressure (MAP) were measured at 15-min intervals after each dose. Respiratory depression was assessed by the presence of: I) slow respiratory rate (SRR-less than 10 breaths per minute for greater than 5 min), 2) apnea (AP-cessation of tidal ventilation for greater than 15 s), and 3) increased Paco2, in arterial blood gases (ABG) drawn at regular intervals. SRR and AP were measured using respiratory inductive plethysmography (RIP). A further group of ten patients (group IV) underwent preoperative RIP monitoring during sleep and in the absence of any drug. Maximum analgesia was achieved within 15 min after a dose of sufentanil for all groups. Analgesia was not significantly prolonged by increasing the dose of sufentanil. SRR occurred in all four groups (group I: 2/9; group II: 2/6; group III: 7/7; group IV: 2/10 P < 0.05 I, IV:II, I, IV:III, II:III). The number of episodes of SRR/hr was highest in group II (group I: 0.6 ± 0.8, group II: 4.12 ± 0.6, group III: 1.8 ± 2.0, group IV: 0.5 ± 0.2) (NS). Mean onset time of SRR after a dose of sufentanil was 38 ± 12 min (group I), 17 ± 12 min (group II), and 19 ± 21 min (group III) (NS). AP occurred in all four groups (group I: 5/9, group II: 3/6, group III: 7/7, group IV: 6/10) (NS). The number of apneas per hour were significantly increased in group III (group I: 1.3 ± 1.2, group II: 3.0 ± 2.8, group III: 4.3 ± 3.7, group IV: 0.4 ± 0.5 P < 0.05 IV:III). Mean onset time of AP after a dose of sufentanil was 18 ± 15 min (group I), 32 ±57 min (group II), and 10 ± 10 min (group III) (NS). Mean duration of AP was 19 ±3 s (group I), 18 ± 3 s (group II), 22 ± 5 s (group III), and 17.5 ± 3 (group IV) (NS). Mean Paco, measured within 30 min of a dose of sufentanil was significantly increased in all groups receiving sufentanil (preoperative PaCo2: group 1:37 ± 3, group II: 36 ±4, group III: 35 ± 1, group IV: 36 ± 3, post-dose PaCo2,: group 1:41 ±5, group II: 46 ± 8, group III: 49 ± 14, P < 0.05 I:III). Three patients receiving 75 μg developed life-threatening respiratory depression. Lumbar epidural sufentanil in patients following thoracotomy produced rapid onset of pain relief that was of short duration. Increasing the dose did not extend the duration of analgesia, but increased respiratory depression.