A proposal to use confidence intervals for visual analog scale data for pain measurement to determine clinical significance

Is lidocaine-prilocaine cream (EMLA) always useful for venous puncture in preoperative autologous blood donation?

PURPOSE

The goal of the present study was to evaluate in adults the benefit of the Eutectic Mixture of Local Anesthetics (EMLA) for preoperative autologous blood donation.

METHODS

Twenty-six adult patients requiring three blood samples were studied. The pain of venipuncture was assessed by the patient using a 100 mm Visual Analogue Scale (VAS) and a four-category Verbal Rating Scale (VRS). The first puncture was performed without anaesthesia, as a "reference puncture". The second and third punctures were performed with EMLA and placebo in a double-blind cross-over randomization. For statistical analysis, the patients were allocated to two groups according to the VAS scores of the reference puncture: (Group 1) VASref < 20 mm; (Group 2) VASref > or = 20 mm.

RESULTS

For the whole 26 patients, the VAS and the VRS pain scores were lower for EMLA puncture than for both the placebo and reference punctures (P < 0.05). Twenty patients had a VASref < 20 mm and six patients a VASref > or = 20 mm. In Group 1, there was no difference between EMLA and placebo for both the VAS and VRS scores. In contrast, in Group 2, the VAS score was lower for EMLA than for both the placebo and the reference punctures (respectively 11 +/- 7.1, 28.9 +/- 7.9, 29.1 +/- 6.4; P < 0.01); the VRS score was also lower for EMLA puncture than for placebo puncture (P < 0.05).

CONCLUSION

In adults requiring repeated venous punctures, pain from cannulation may be evaluated at the first puncture with a Visual Analogue Scale, thus indicating or not the need for EMLA.

[Comparative study of buprenorphine and its combination to ketoprofen or propacetamol for postoperative analgesia in urologic surgery]

OBJECTIVE

To compare the analgesic effect of subcutaneous buprenorphine alone and in combination with propacetamol and ketoprofen following urologic surgery.

STUDY DESIGN

Open randomized clinical trial.

PATIENTS

Sixty ASA II/III patients undergoing urologic surgery.

METHODS

The patients were randomized into three groups to receive either buprenorphine (0.3 mg subcutaneous) on demand (group 1, n = 20), or a combination of buprenorphine (0.3 mg)-propacetamol (2 g)-ketoprofen (100 mg) by intravenous route over 2 hours followed by an infusion of propacetamol (2 g) and ketoprofen (100 mg) at a constant rate over. The remaining 22 hours (group 2, n = 20), or the same loading dose as in group 2 prolonged by a continuous infusion of buprenorphine (0.3 mg), propacetamol (2 g) and ketoprofen (100 mg) over the same period (group 3, n = 20). Visual analogue scale pain scores (0-10) were assessed every hour during the 24 hours of the study. When the VAS score exceeded 5, an additional dose of 0.3 mg of buprenorphine was administered.

RESULTS

Groups were similar for age, surgery, anaesthesia and initial pain levels. Compared to group 1, the onset of analgesia was earlier in groups 2 and 3 at the 1st hour (P < 0.05); the level of analgesia was lower at the 3rd hour (P < 0.05). The maintenance of this analgesia level required constant buprenorphine administration. Buprenorphine requirements were decreased to 56% and 37% in groups 2 and 3 respectively, compared to group 1 (P < 0.05). Incidence of nausea and vomiting was lowered to 15% in group 3 (P < 0.05).

CONCLUSION

A combination of buprenorphine, propacetamol and ketoprofen provides effective postoperative analgesia with a low incidence of nausea and vomiting and decreased requirements of buprenorphine.

A new axillary approach for continuous brachial plexus block. A clinical and anatomic study

Catheter insertion in the neurovascular space by axillary approach allows a continuous brachial plexus block and/or postoperative analgesia. We developed a perivenous technique whereby the approach to the neurovascular sheath is guided under fluoroscopy by a preopacified axillary vein. A randomized study compared this technique to the technique of Selander in ASA grade I-II patients scheduled for surgery or painful physiotherapy of the hand. The study was performed in 36 patients randomly divided into two groups. In Group 1 (n = 18), the catheter was placed according to the technique described by Selander. In Group 2 (n = 18), the catheter was placed using our perivenous technique. A complete block was obtained in all the patients of Group 2 vs only 50% of the patients in Group 1 (P < 0.05). In Group 1 a partial block was observed in 17%, with failure in 33% of the patients. There was no difference in the two groups regarding the time required to perform either technique, the duration of the complete block, the pain score, or the amount of continuously administrated bupivacaine during the first 48 h postoperatively. The plasma concentrations of total bupivacaine (high-performance liquid chromatography) were low in successful blocks, with no differences in the two groups; the median value was 0.68 microgram/mL (95% confidence interval: 0.62-0.89). The concentrations were higher (P < 0.01) in failed blocks; the median value was 1.69 micrograms/mL (95% confidence interval: 0.58-2.8). A complementary anatomic study of three arms from fresh cadavers allowed verification of the correct localization of the Teflon cannula and flexible catheter, as well as homogeneous diffusion of the methylene blue inside the brachial plexus. The perivenous technique for continuous axillary brachial plexus block may improve the success rate due to its radiologic and accurate location of the neurovascular sheath.

Comparative analgesic efficacy of patient-controlled analgesia with ketorolac versus morphine after elective intraabdominal operations

We conducted a randomized, double-blind trial to compare analgesia and side effects produced by ketorolac and morphine during postoperative patient-controlled analgesia (PCA). Fifty-one patients (ASA classes I and II) undergoing elective intraabdominal procedures were assigned to one of two groups. When postoperative pain first increased to 4/10 (by visual analog scale [VAS]), patients were randomly assigned to one of two groups. Group 1 (n = 25) received up to two intravenous (IV) boluses of 5 mg of morphine followed by IV morphine PCA, whereas those in Group 2 (n = 26) received up to two IV boluses of 30 mg ketorolac, then IV ketorolac PCA. Up to two rescue doses of morphine (5 mg per dose, subcutaneously) were given in either group when pain during deep inhalation exceeded 5/10 on VAS. Ten patients from Group 1 required rescue doses of morphine compared to 22 patients from Group 2 (P < 0.0011). Two and 16 patients from Groups 1 and 2, respectively, were withdrawn because of inadequate analgesia (P < 0.01). Mean pain scores were less in Group 1 than in Group 2 at each time, but only significantly so at 15 min (P < 0.0021), 30 min (P < 0.0336), and 24 h (P < 0.0358) after starting PCA. Time to acceptance of oral liquids was equivalent in Groups 1 and 2 (22 h and 21 h, respectively). IV ketorolac PCA, although well tolerated, has limited effectiveness as the sole postoperative analgesic after intraabdominal operations.

Comparison of tetracaine-adrenaline-cocaine (TAC) with topical lidocaine-epinephrine (TLE): efficacy and cost

Topical anesthesia in the form of TAC (tetracaine, adrenaline, cocaine) solution has been used for wound repair. This pilot study was designed to determine if the topical anesthesia achieved using a mixture of lidocaine (5%) and epinephrine (1:2000) (TLE) is equivalent to the topical anesthesia obtained using a solution of tetracaine (0.5%), epinephrine (1: 2000), and cocaine (10.4%) (TAC). A prospective, randomized, double-blind trial was carried out from May 1992 to August 1992 at a community-based teaching hospital Emergency Department (ED) that receives 50,000 annual visits. Patients with facial or scalp lacerations suitable for topical anesthesia presenting to the ED were included when study physicians were in attendance. Exclusion criteria included the presence of a sensory altering substance (eg, ethanol), age younger than two years, hypertension, pregnancy, allergy to any of the study's pharmacological agents, wounds greater than six hours old, grossly contaminated wounds, and wounds longer than six centimeters. Either a TAC or TLE solution was applied to lacerations before suturing. The laceration was repaired and the patient or physician evaluated the degree of pain from the procedure by using a standardized visual pain scale. A total of 35 patients were studied. Seventeen patients were in the TLE group; 18 in the TAC group. The mean ages were compared and found to be similar (P = .40) between the two test groups. The pain scale values, the diameter of tissue blanch around laceration (halo size), and the time to laceration repair from the onset of application of anesthetic were compared and no difference was shown between the TAC and TLE groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Painless needle insertion in regional anesthesia of the eye

We examined a new technique of applying topical anesthetic with cotton tip sticks to the conjunctiva before needle insertion in regional anesthesia of the eye. Oxybuprocaine 0.4% and lidocaine 4% were compared with balanced salt solution (BSS) as topical anesthetics of the conjunctiva in Study 1. Ninety patients were randomly assigned into three groups (n = 30) to receive one of the three topical anesthetics in a double-blind manner. Pain of the needle insertions was measured with visual analog scale score (VAS) and quantitative surface electromography (qEMG). Both oxybuprocaine and lidocaine reduced pain significantly when compared to BSS. In Study 2, with healthy volunteers, we compared our previous practice of merely applying three consecutive drops of oxybuprocaine on the conjunctiva before needle insertions to the new technique of placing additional cotton tip sticks soaked in oxybuprocaine on the conjunctiva. We found the needle insertion virtually pain free when the cotton tip sticks were added to the topical anesthesia. The use of this simple method of topical anesthesia before the eye block increases patient comfort significantly.

Effect of interpleural administration of bupivacaine or lidocaine on pain and morphine requirement after esophagectomy with thoracotomy: a randomized, double-blind and controlled study

The purpose of the present study was to investigate the efficacy of interpleural (IP) analgesia with bupivacaine or lidocaine after esophageal surgery and to measure the plasma concentrations of bupivacaine and lidocaine after intermittent IP administrations. Two IP catheters were inserted percutaneously in the seventh intercostal space during operation. Patients in the bupivacaine group (Gr B) received 1 mg/kg of 0.5% bupivacaine with epinephrine 1:200000 in 20 mL of saline 0.9%, patients in the lidocaine group (Gr L) received 3 mg/kg of 2% lidocaine with epinephrine in 20 mL of saline 0.9%, and patients in the placebo group (Gr P) received 20 mL of saline 0.9% every 4 h during 2 days. Pain was assessed by visual analog scale (VAS) every 4 h at rest (VASR), after a deep breath or cough (VASC), at the thoracotomy (VAST), and at the laparotomy (VASL). Morphine consumption using a patient-controlled analgesia (PCA) device was recorded. There was no significant difference in the mean VASR, VASC, and VASL scores among the three groups. VAST scores were significantly lower in Gr B at 12, 16, 28, and 32 h when compared with Gr P and Gr L (P < 0.05). There was no statistical difference in mean VAST between Gr L and Gr P. Total consumption of morphine was lower in Gr B than in Gr P and Gr L (41.2 +/- 13 mg vs 66.1 +/- 21 mg in Gr P (P < 0.02) and 75.5 +/- 27 mg in Gr L (P < 0.01)), but were similar in Gr L when compared with Gr P.(ABSTRACT TRUNCATED AT 250 WORDS)

[Comparison of extrapleural and intrapleural analgesia with bupivacaine after thoracotomy]

OBJECTIVE

To compare the analgesic and the ventilatory effects as well as blood concentrations of bupivacaine, administered either in the extrapleural or interpleural space after posterolateral thoracotomy.

STUDY DESIGN

Randomized clinical trial.

PATIENTS

Twenty ASA class I and II patients, scheduled for elective thoracic surgery were randomly allocated either in the IP group (catheter inserted into the interpleural space) or the EP group (catheter inserted in extrapleural position, paravertebrally above the posterior parietal pleura).

METHODS

In the catheter, inserted at the Th4 level at the end of the surgical procedure, 20 mL of 0.5% bupivacaine were injected after full recovery from anaesthesia, with the thoracic drains clamped for 30 min. The injection was repeated every six hours. Pain was evaluated after a deep inspiration with a visual analog scale (VAS), before and 1.3 and 6 hours after the injection. Analgesia was considered as effective if the VAS score at the end of the first hour was less than 30 mm. Otherwise 0.1 mg.kg-1 of morphine was administered subcutaneously. The forced vital capacity (FVC) and the forced expiratory volume one second (FEV1) were measured preoperatively and on 1st (D1) and 2nd postoperative Day (D2). Blood samples for measurements of plasma bupivacaine concentrations were obtained at 5, 10, 20, 30, 60, 90, 120, 150, 180 and 250 min respectively after the first injection.

RESULTS

Bupivacaine provided a more rapid, deep and prolonged analgesia by extrapleural than by interpleural route. Analgesia was effective in 9 patients in EP group vs 4 patients in IP group (P < 0.05). Morphine requirements were 4 +/- 8 mg in EP group vs 17 +/- 10 mg in the IP group (P < 0.05). The FVC and FEV1 values were similarly decreased on D1, but recovery was better in EP group on D2 (P < 0.05). Bupivacaine peak concentrations in plasma were lower in EP group (0.86 +/- 0.42 microgram.mL-1) than in IP group (1.63 +/- 1.44 micrograms.mL-1), however the difference was not significant.

CONCLUSIONS

Extrapleural administration of bupivacaine provides better analgesia as the anaesthetic agent comes in closer contact with intercostal nerves and with lower risk of loss of agent through the pleural drainage. Therefore its use is recommended preferentially over the interpleural route for analgesia after posterolateral thoracotomy.