Comparison between epidural infusion of fentanyl/bupivacaine and morphine/bupivacaine after orthopaedic surgery

0 Marco Berti MD, Guido Fanelli MD, Andrea Casati MD, Daniele Lugani MD, Giorgio Aldegheri MD, Giorgio Torri MD P u r p o s e : To compare epidural infusions of bupivacaine-fentanyl and bupivacaine-morphine mixtures for postoperative pain relief after total hip replacement. M.r In a prospective, randomized, double-blind study, 30 ASA physical status I-II patients undergoing total hip replacement were studied. Anaesthesia was provided by combined general/epidural anaesthesia without epidural opioids. Postoperative epidural analgesiawas by continuous infusion of bupivacaine 0.125% (4 ml.hr :~) with either 0.05 mg.ml -~ morphine (morphine, n = I 5) or 0.005 mg'ml-u fentanyl (fentanyl, n = 15). Visual analogue pain scale 0/AS), sedation (fourpoint scale), respiratory rate, pulse oximetry, rescue analgesicsand supplemental oxygen were recorded by a blind observer at 1,3, 6, 9, 12 and 24 hr after surgery. Results" No differences in pain relief, sedation, or non-respiratory side effects were observed between the two groups. Rescue analgesics were required in three patients in the fentanyl group (20%) and in two receiving morphine (13.3%) (P:NS). Two patients in the fentanyl group and three in the morphine group required oxygen due to SpO2 < 90% (P:NS). Both opioidlbupivacaine mixtures decreased haemoglobin oxygen saturation compared with preoperative values. The mean -_+SD SpOz values measured at 3, 6, 12 and 24 hr were 94.4 --- I, 92.6 ___0.9, 92 _ 0.8, and 92.8 _ I in the morphine group, 95.3 ___0.5, 95 __+0.S, 94.6 __. 1.2, and 95.6 --- I in the fentanyl group (P < 0.05). Conclusion: Continuous epidural infusion of bupivacaine-morphine or bupivacaine-fentanyl mixtures provided similar pain relief. Patients receiving morphine showed a more marked decrease in SpO2 than those receiving fentanyl. However, the average SpO2 remained > 90% in both groups. O b j e c t i f 9 Comparer des perfusions Epidurales de melanges de bupivacai'ne-fentanyl et de bupivaca'(ne-morphine utilis~s comme analg&ique post op&atoire ~ la suite de la mise en place d'une proth~se totale de la hanche. M & h o d e s : Dans une &ude prospective, randomis~e et en double insu, on a &udi(~ 30 patients ASA de condition phy sique I et II, devant subir la mise en place d'une prothEse totale de la hanche. On a proc~d~ ~ une anesth&ie gEn&ale combinEe ~ une anesth&ie ~pidurale sans opio'ides Epiduraux. l'analgEsie Epidurale post opEratoire consistait en une perfusion continue de bupivaca'(ne 0, 125 % (4ml'hr-i) avec, soit 0,05 mg.mlIde morphine (morphine, n = IS), soit 0,005 mg.ml'Ide fentanyl (fentanyl, n = 15). l'~chelle visuelle analogique (EVA) de la douleur, la sedation (&helle en quatre points), la frEquence respiratoire, l'oxym~trie de pouls, les doses analg&iques de rattrapage et l'oxyg~ne de suppl~ment ont Et~ enregistr& par un observateur aveugle ~ la r~partition ~ I, 3, 6, 9 12 et 24 heures aprEs la chirurgie. R ~ i x l t a t s : Aucune difference dans l'analg~sie, la s(~dation ou les effets secondaires non respiratoires n'a ~t~ observ~e entre les deux groupes. Des analg&iques de rattrapage ont Et~ n&essaires pour trois patients dans le groupe qui avait re~u du fentanyl (20 %) et pour deux patients dans le groupe ayant re~u de la morphine ( 13,3 %) (P : NS). Deux patients dans le groupe fentanyl et trois dans le groupe morphine ont eu besoin d'oxygEne ~ la suite d'une SpO2 < 90 % (P : NS). Les deux melanges d'opio'(de et de bupivaca'l'ne diminuent la saturation en oxyg~ne de l'h~moglobine par rapport aux valeurs pr~ op&atoires. La moyenne _+ l'Ecart type des valeurs de la SpO2 mesurEe ~ 3, 6, 12 et 24 heures ont ~t~ de 94,4 --- I ; 92,6 --- 0,9 ; 92 --- 0,8 et 92,8 --- I dans le groupe morphine, 95,3 ___0,5 ; 95 --. 0,5 ; 94,6 --- 1,2 et 95,6 --. I dans le groupe fentanyl (m < 0,05). C_~nclmion : Une perfusion ~pidurale continue du m~lange de bupivaca~'ne-morphine ou du m~lange de bupivaca'~'ne-fen tanyl foumit une analg&ie semblable. Les patients qui ont re~u de la morphine ont montr~ une plus grande diminution de la SpO~ que ceux qui ont recju du fentanyl. Toutefois, la moyenne de la SpO2 demeure > 90 % darts les deux groupes. - OSTOPERATIVE epidural analgesia by means of opioid and local anaesthetic mixtures is an effective method for the management o f postoperative pain. Although contrasting results have been reported in humans studies,1-7 a synergistic effect between local anaesthetic and opioids has been demonstrated in animal models, in which the antinociceptive effects of opioid/local anaesthetic mixtures were greater than those of opioid or local anaesthetic alone,s Since hydrophilic opioids, such as morphine, remain in the cerebrospinal fluid and may be responsible for undesirable side effects (e.g. delayed onset o f peak analgesic effect and late respiratory depression), highly lipophilic opioids such as fentanyl have been used to reduce the side effects of extradural opioid administration, sq~ The goal o f the present investigation was to compare, in a double-blind study, the analgesic effect o f postoperative epidural infusions o f either bupivacainemorphine or bupivacaine-fentanyl mixtures after total hip replacement. M e t h o d s The study protocol was approved by Hospital Ethics Committee, and informed consent was obtained from each patient. Patients undergoing elective total hip replacement and having an epidural catheter as part o f their anaesthetic technique participated in the study. Obese patients as well as patients with pulmonary, cardiac, renal, hepatic, cerebrovascular, or psychiatric disease were excluded from the study. The day before surgery baseline peripheral haemoglobin oxygen saturation was measured with the patients spontaneously breathing room air (Oxypac Station, Dr~iger, Germany), and all patients were educated in the use o f the 100 mm visual analogue pain scale (VAS). After arrival in the operating theatre, patients received a standard intravenous infusion o f 10 ml-kg-1 Ringer's lactate solution, then an epidural catheter was inserted at the Ls-L4 or L2-Ls interspace. After an epidural test dose (60 mg lidocaine 2%) confirmed the correct catheter location, epidural block up to T~0 (loss of pinprick sensation) was induced by 10-12 ml lidocaine 2%. Before induction o f general anaesthesia, all patients received 1 lag.kg-1 fentanyl iv; then combined general (isofluranerT 0.2 - 0.6%) and epidural anaesthesia (continuous infusion 3-5 ml-hrq bupivacaine 0.5%) was provided. No epidural opioids were given until the start o f postoperative epidural infusion. Standard ASA monitoring was used during surgery. Before the cement for the prosthesis had been applied, the lungs were ventilated with oxygen 100% and 5 mg.kg-1 hydrocortisone iv were administered. Patients developing a sudden decrease in oxygen saturation and hypocapnia at the time of prosthesis cementation were excluded from the study. Using sealed envelopes, patients were randomly allocated to two grou (...truncated)