Pain scores in infants: a modified infant pain scale versus visual analogue.

This study describes an observational system (modified infant pain scale, MIPS) with elements from a previously published observational scale and from assessments of video-recorded infant facial expressions. It was designed to allow rapid and repeated assessments of pain in infants after brief training by an observer without pediatric experience. Forty healthy term infants (17 +/- 7 weeks) undergoing elective surgery had simultaneous independent assessment of pain using two scales: a naive observer used the MIPS and an experienced pediatric nurse used a 10-cm unmarked horizontal visual analogue scale (VAS). This validation of the MIPS included its division during analysis into partial (P-MIPS, without data on sleep or vital signs) and total scores. Infants had a broad range of MIPS scores, and the two scales categorized infants as "comfortable" or "not comfortable" with a high degree of concordance. The MIPS was easily incorporated into an infant's physical examination. We recommend its use for two-point clinical pain assessment.

Epidural and intravenous bolus morphine for postoperative analgesia in infants.

PURPOSE: To compare two doses of bolus epidural morphine with bolus iv morphine for postoperative pain after abdominal or genitourinary surgery in infants. METHODS: Eighteen infants were randomly assigned to bolus epidural morphine (0.025 mg.kg-1 or 0.050 mg.kg-1) or bolus iv morphine (0.050-0.150 mg.kg-1). Postoperative pain was assessed and analgesia provided, using a modified infant pain scale. Monitoring included continuous ECG, pulse oximetry, impedance and nasal thermistor pneumography. The CO2 response curves and serum morphine concentrations were measured postoperatively. RESULTS: Postoperative analgesia was provided within five minutes by all treatment methods. Epidural groups required fewer morphine doses (3.8 +/- 0.8 for low dose [LE], 3.5 +/- 0.8 for high dose epidural [HE] vs. 6.7 +/- 1.6 for iv, P < 0.05) and less total morphine (0.11 +/- 0.04 mg.kg-1 for LE, 0.16 +/- 0.04 for HE vs 0.67 +/- 0.34 for iv, P < 0.05) on POD1. Dose changes were necessary in all groups for satisfactory pain scores. Pruritus, apnoea, and haemoglobin desaturation occurred in all groups. CO2 response curve slopes, similar preoperatively (range 36-41 ml.min-1.mmHg ETCO2-1.kg-1) were generally depressed (range, 16-27 ml.min-1.mmHg ETCO2-1.kg-1) on POD1. Serum morphine concentrations, negligible in LE (< 2 ng.ml-1), were similar in the HE and iv groups (peak 8.5 +/- 12.5 and 8.6 +/- 2.4 ng.ml-1, respectively). CONCLUSION: Epidural and iv morphine provide infants effective postoperative analgesia, although side effects are common. Epidural morphine gives satisfactory analgesia with fewer doses (less total morphine); epidural morphine 0.025 mg.kg-1 is appropriate initially. Infants receiving epidural or iv morphine analgesia postoperatively need close observation in hospital with continuous pulse oximetry.

Variation in opioid use during PCA in adolescents.

The objective of this investigation was to determine if the variability in the use of opioids for pain following surgery is related to variability in blood concentration of opioids used for pain relief. We measured morphine use and morphine blood concentration in a group of otherwise healthy adolescent girls following spinal surgery. There was considerable variability in morphine use and morphine blood levels as indicated by a large range of values and a moderately large standard deviation. Morphine blood concentration correlated with morphine use. Neither morphine use nor morphine concentration correlated with pain scores. The data indicate that there is considerable variability among patients in the amount of opioid needed to achieve comfort and in the blood concentration associated with comfort. The cause of this variability does not appear to be related to metabolism of opioid, but may be related to psychological differences, differences in pain tolerance and threshold, or differences in the way patients use PCA.