Postoperative patient-controlled analgesia with sufentanil: analgesic efficacy and minimum effective concentrations.

Sufentanil has so far seldom been used for intravenous postoperative patient-controlled analgesia (PCA), and the resulting serum concentrations have not yet been determined. Forty ASA I-III patients recovering from major gynecological operations were investigated to evaluate analgesic efficacy, side effects, patient acceptance and threshold concentrations of sufentanil in serum during the early postoperative period, using the On-Demand Analgesia Computer (ODAC). Following an individualized intravenous loading dose of 19.1 +/- 35.7 micrograms (mean +/- 1 s.d.), sufentanil demand doses were 6 micrograms with a concurrent infusion of 1.15 micrograms/h and a maximum hourly dose of 40 micrograms/h; the lockout time was set to 1 min. The duration of PCA was 17.3 +/- 2.1 h. During this time 16 +/- 11 demands per patient were recorded, resulting in an average sufentanil consumption of 131.1 +/- 69.4 micrograms or 7.5 +/- 3.7 micrograms/h (including loading dose). analgesia was mostly judged good. Side effects were only of minor intensity. Sufentanil proved to be about 2.2 to 3.8 times as potent an analgesic as fentanyl when both analgesic effect and duration were considered. Minimum effective sufentanil serum concentration (MEC) as determined by radioimmunoassay varied greatly and could be best described by a log-normal distribution (range less than 0.01-0.56 ng/ml, median 0.024 ng/ml). Intraindividual MEC variability was slightly lower than intersubject variability (76.0 vs. 84.8%). It is concluded that sufentanil is suitable for postoperative PCA. To get into the therapeutic window for analgesia, a serum sufentanil concentration of more than 0.03 ng/ml seems to be necessary.

Postoperative patient-controlled analgesia with tramadol: analgesic efficacy and minimum effective concentrations.

Forty patients (ASA status I-III) recovering from major orthopedic or gynecological operations were investigated to evaluate analgesic efficacy and threshold concentrations of tramadol and its main metabolite O-demethyltramadol (M1) in serum during the early postoperative period, using patient-controlled analgesia (PCA) by means of the Abbott Lifecare Infuser. Following an individualized intravenous loading dose of 97.5 +/- 42.3 mg (mean, SD), tramadol demand doses were 20 mg with a limit of 500 mg within 4 h; the lockout time was set to 5 min. The duration of PCA was 20.5 +/- 4.8 h. During this time 8.0 +/- 5.0 demands per patient were recorded, resulting in an average tramadol consumption of 257.5 +/- 102.8 mg (including loading dose). Analgesia was mostly judged good to excellent. Side effects were only of minor intensity and never gave rise to concern. There were no statistically significant differences between the types of surgery. Tramadol proved to be about 1/6 to 1/10 as potent an analgesic as morphine when both intensity and duration of effect were considered. Minimum effective tramadol serum concentration (MEC) varied greatly and could be best described by a log-normal distribution (range 20.2-986.3 ng/ml, median 287.7 ng/ml). Intraindividual MEC variability was lower than intersubject variability (38.2 vs 59.1%). Median M1 concentrations were 36.2 ng/ml.

Postoperative patient-controlled analgesia with alfentanil: analgesic efficacy and minimum effective concentrations.

Forty ASA I-III patients recovering from major abdominal or orthopedic operations were investigated in an open clinical study to evaluate analgesic efficacy and threshold plasma concentrations of alfentanil during the early postoperative period using patient-controlled analgesia (PCA) by means of the On-Demand Analgesia Computer. Alfentanil demand dose was 212 micrograms, continuous infusion rate 25 micrograms/hr, hourly maximum dose 1.5 mg/hr; the lockout time was set to 1 min. The duration of PCA was 18.1 +/- 5.2 hr (mean, SD) during which time 23.8 +/- 14.2 demands per patient were recorded, resulting in an average alfentanil consumption of 4.99 +/- 3.03 micrograms/kg/hr. Patient acceptance of PCA was high. Side effects were only of minor intensity and never gave rise to concern. Based on our own earlier PCA experience with other opiate analgesics, alfentanil proved to be about 1/15th as potent an analgesic as fentanyl and about 6-7 times more potent than morphine if both intensity and duration of effect were considered. Minimum effective alfentanil plasma concentration (MEC) varied greatly and could be best described by a lognormal distribution (range 0.6-99.2 ng/mL, median 14.9 ng/mL). Intraindividual MEC variability was consistently lower than intersubject variability (37.0% vs 65.2%).

[Postoperative pain therapy with 1-methadone and metamizole. A randomized study within the scope of intravenous on-demand analgesia]. / Postoperative Schmerztherapie mit 1-Methadon und Metamizol. Eine randomisierte Untersuchung im Rahmen der intravenösen On-Demand Analgesie.

Methadone, a potent long-acting opioid analgesic, is only seldom prescribed for postoperative pain relief in Germany. It was the aim of the present investigation to evaluate its efficacy and to establish an adequate dose range using intravenous patient-controlled analgesia (PCA), as well as to determine possible drug interactions with the antipyretic analgesic metamizol (dipyrone). 120 patients recovering from elective major abdominal, gynaecological or orthopaedic surgery under standardized balanced anaesthesia were randomly allocated to three groups to self-administer intravenous 1-methadone. Demand doses were 0.573 mg (group LD), 1.145 mg (group HD) or 0.573 mg to which 50 mg metamizol (dipyrone) were added (group LM). Infusion rate was set to 0.137 mg 1-methadone/h in every group, lockout time was 1 min. Hourly maximum dose was set to 5.95 mg 1-methadone/h. During an average PCA duration of 21 hours patients demanded mean dosages of 16.4 mg (LD), 18.7 mg (HD) or 13.4 mg (LM) 1-methadone. Although individual variation in drug consumption was high, effective pain relief was possible in all cases. Cardiovascular and respiratory status during the observation period was always normal. 88-93% of patients preferred PCA in comparison with earlier experienced conventional postoperative pain treatment. It is concluded that patients are able to control adequate drug consumption, i.e. to avoid overdosage, by adjusting demand frequency if variable demand dosages are offered. Thus 13-19 mg 1-methadone per day can be recommended as reasonable dose range for pain relief during the early postoperative period.(ABSTRACT TRUNCATED AT 250 WORDS)

[Occlusion of an implanted peridural catheter by a plug of epidermis]. / Okklusion implantierter Periduralkatheter durch Epidermisstanzen.

A patient suffering from intensive perianal pain due to recurrent rectal cancer, not controllable by systemic analgesics, was treated by continuous epidural morphine for a period of 8 months. Satisfactory pain relief was achieved although sometimes problems arose with the permeability of the epidural catheter. As a reason for increased resistance, the literature mentions nonspecific foreign-body reactions next to the catheter. In our patient, tumour infiltration into both the lumbosacral plexus and the epidural space leading to compression of the catheter could not positively be excluded. At autopsy an unexpected obstruction of the catheter by epidermis was observed. It could be demonstrated that pieces of epidermis may enter the catheter, bypassing the bacterial filter of the port, and can then clog the tip of the catheter.

[Pain relief in the final stage of cancer.]. / Schmerztherapie in der Finalphase maligner Erkrankungen.

Most patients with very advanced cancer suffer from severe pain, and many studies have demonstrated how this pain can be sufficiently controlled. It is of great importance to find out if the findings are also true during the final stage of cancer and how the treatment must be adapted. We therefore examined the methods and efficacy of providing pain relief for dying cancer patients. This study included 160 patients with cancer in different sites. The pain treatment and pain severity during the last few days and hours of their lives are described and discussed. Analgesic drugs administered orally in 53% and parenterally in 39% of the patients were the mainstay of therapy. Non-opioid analgesics alone were effective in 10% and in combination with weak opioids in 15% of the patients. In 68% strong opioids were necessary to achieve sufficient pain reduction. Morphine was the most frequently used opioid for 96 patients. Oral doses of morphine were 86+/-60 mg/day (15-240 mg/day), and parenteral doses 89+/-74 mg/day (15-360 mg/d). Additional adjuvant drugs to treat specific types of pain or other symptoms of cancer disease were described for 80% of the patients. Non-pharmacological measures, such as radiation, nerve blocks or neurosurgery, were of no real importance. Only 4% of the patients treated in the way described experienced severe pain during the final stage of cancer. Systemic administration of drugs is very effective in relieving pain in dying patients. No signs of tolerance to opioids could be observed, even in patients who had been taking opioids for a longer period of time (average 39 days).