CONTINUOUS-INFUSION OF OPIOID AND BUPIVACAINE BY EXTERNALIZED INTRATHECAL CATHETERS IN LONG-TERM TREATMENT OF REFRACTORY NONMALIGNANT PAIN

Objective: To explore the possibility of obtaining pain relief by cont inuous intrathecal infusion of bupivacaine and opioid in patients with intractable nonmalignant pain. Design: Prospective, cohort, nonrandom ized, consecutive trial. Setting: Tertiary care center, institutional practice, hospitalized, and ambulatory care. Patients: A total of 90 p atients, 40 men and 50 women, 20 to 96 years old (median, 70 years), w ith various nonmalignant ''refractory'' pain conditions lasting for 0. 3 to 50 years (median, 3 years) with nociceptive (n = 9), neurogenic/n europathic (n = 17), and mixed pain (n = 64) were consecutively includ ed in the study when (a) the pain dominated their lives totally, (b) o ther methods failed to provide acceptable pain relief, and (c) unaccep table side effects from opioids had occurred. Moribund patients and th ose with overt psychoses at the time of the assessment were excluded f rom the study. Interventions: (a) Insertion of externalized, tunnelled intrathecal catheters (101 in 90 patients). ib) Intrathecal infusion of opioid (morphine 0.5 mg/ml; or buprenorphine 0.015 mg/ml, and/or bu pivacaine 4.75-5.0 mg/ml) from external electronic pumps was started i n the operating room at a basic rate of 0.2 ml/hour, with optional bol us doses (0.1 ml 1-4 times/hour) by patient-controlled analgesia (PCA) . Thereafter, the daily volumes were tailored to give the patients sat isfactory to excellent (60-100%) pain relief, with acceptable side eff ects from the infused drugs, by increase or decrease of the basic rate s and/or of the bolus doses, and their timing. (c) Supervision of the patients for 24 hours after catheterization in the postoperative ward. (d) Daily phone contact with the patients, their families, or the nur ses in charge. (e) The patients had ad libitum access to nonopioid ana lgesics/sedatives and to opioids administered by various routes, until they obtained satisfactory pain and anxiolytic relief. Main Outcome M easures: (a) Pain intensity (visual analog scores 0-10) and pain relie f (0-100%). (b) Daily dosages (opioid administered by intrathecal and other routes, and intrathecal bupivacaine). (c) Scores (0-5) of nonopi oid analgesics, gait and ambulation; duration of nocturnal sleep, and (d) rates of adverse effects. Results: During the intrathecal period [ range, 3-1,706 days; median, 60 days; totaling 14,686 days, 7,460 (50% of which were spent at home)], 86 patients (similar to 95%) obtained acceptable (60-100%) pain relief. The nocturnal sleep duration increas ed from <4 to 7 hours (median values), nonopioid analgesic and sedativ e daily consumption became approximately two times lower, whereas the gait ability and ambulation patterns remained practically unchanged. F ive patients still had ongoing treatment after durations of 30 to 1,70 7 (median, 206) days at the close of the study. In the remaining 85 pa tients, the intrathecal treatment was terminated because of patients' death (n = 23), replacement of the intrathecal treatment by dorsal col umn stimulation (n = 1), pain resolution (n = 32), refusal to continue the intrathecal treatment (n = 19), lack of cooperation due to deliri um or to manipulation of the pump (n = 8), and loss of efficacy of the intrathecal treatment (n = 2). Thus, in the long run, the intrathecal treatment failed in 29 of the 85 patients with terminated treatment ( 34%). The principal side-effects and complications, except those attri buted to the dural puncture, the equipment, and the long-term catheter ization of the subarachnoid space, which are presented separately, wer e severs bradypnea (n = 1), transient paresthesiae (n = 26), short-las ting pareses (n = 16), temporary urine retention(n = 34), episodic ort hostatic arterial hypotension (n = 11), anti attempted suicide (n = 5, 3 of which were successful). No neurologic sequelae or death could be attributed to the intrathecal procedure. Conclusions: (a) Intrathecal infusions of opioid and bupivacaine initially provided satisfactory; (60-100%) pain relief in 95% of the patients with ''refractory'' nonma lignant pain conditions. (b) In the long run, the intrathecal treatmen t with opioid/bupivacaine failed in 34% of the treated patients (insuf ficient pain relief 2.3%, lack of patient compliance 9.4%, refusal of further treatment 22.3%).