Jean D. Powers

Pediatric Pain Measurement Using a Visual Analogue Scale: A Comparison of Two Teaching Methods

The goals of this study were to evaluate the validity of the visual analogue scale (VAS) for young children and to compare a newly developed method of teaching children to use a VAS with one used in our previous studies. It was hypothesized that the new method would increase the number of children who understand the VAS and correctly mark their responses on the VAS line. The association between childs age and ability to understand the VAS was also evaluated. One hundred-six children with a laceration requiring sutures and receiving a lidocaine injection for local anesthesia participated in the study. They ranged in age from 5 to 14 years. Two outcome measures were used to assess the baseline and lidocaine injection pain: a 5-point Likert scale and a VAS. A calibration study was used to determine whether the subjects were able to use the VAS to make proportional judgments about their perceptions. Teaching method had no effect on the number of subjects who could correctly mark their responses on the VAS line, nor did it significantly increase the number of subjects who could understand the concept of the VAS. Subjects who were able to understand the VAS were significantly older (mean = 9.8 years, SD = 2.8) than those who did not (mean = 8.2 years, SD = 2.5). Overall, only about one third of the subjects were able to correctly mark the VAS and understand the concept of the VAS. Other measures of pain that are better understood by young children may be more valid indicators of pain than the VAS.

Prilocaine-phenylephrine and bupivacaine-phenylephrine topical anesthetics compared with tetracaine-adrenaline-cocaine during repair of lacerations

The effectiveness of two new topical anesthetics that do not contain cocaine (prilocaine-phenylephrine and bupivacaine-phenylephrine) was compared with that of tetracaine-adrenaline-cocaine (TAC) during laceration repair in children. This study was a prospective, randomized, double-blind trial conducted in the emergency department of a large childrens hospital. Participants were 180 children 1 year of age or older with a laceration 5 cm or less in length that required suturing. Pain felt during suturing was scored by suture technicians, research assistants, parents, and patients 5 years of age and older using a visual analogue scale (VAS). There was no statistical difference demonstrated between the effectiveness of prilocaine-phenylephrine and that of TAC for any of the observer groups. A statistically significant difference was seen among anesthetics when comparing VAS scores of research assistants (P = .002), suture technicians (P = .006), and parents (P = .03), but not when comparing VAS ratings of patients (P = .07). Based on Tukeys post hoc test, these statistically significant differences were between TAC and bupivacaine-phenylephrine. When power analyses were performed using alpha = 0.05 and beta = 0.20, it was possible to detect a difference of 1.3 VAS units for each rater group. In conclusion, this study demonstrated the effectiveness and safety of prilocaine-phenylephrine and bupivacaine-phenylephrine. Prilocaine-phenylephrine statistically outperformed bupivacaine-phenylephrine and offers an effective alternative to TAC during laceration repair in children.

Statistical Considerations in Pharmacokinetic Study Design

SummaryPharmacokinetic studies may generally be categorised into 3 types: (a) population-based investigations, (b) individual-based compartmental, or (c) individual-based noncompartmental research projects. Each type of study has advantages and limitations.Population-based investigations pool drug concentrations across more than 1 individual subject. From these data, estimates of pharmacokinetic parameters are calculated. NONMEM is the only computer program available to evaluate this type of information. Recently a method has been proposed which derives individual estimates from the information available from NONMEM. By combining these 2 procedures it is possible for the clinician to review and adjust the dosage regimen if necessary.Population-based studies require fewer design criteria than other methods and are adaptable to the clinical setting, i.e. subjects can be patients currently being treated with the drug under consideration. One distinct advantage to this type of study is the flexibility of sampling times and the capability of the clinician to use information from the critically ill, the geriatric patient or the very young child. These subjects would not be available for the individual-based type of study because of the relatively large number of samples needed.Individual-based pharmacokinetic studies can be divided into 2 types with respect to their evaluation: (a) compartmental and (b) noncompartmental investigations. The latter type of study was originally thought to require fewer assumptions than the former but subsequently it has been shown that noncompartmental analyses are more restrictive and are basically compartmental in their approach. These studies estimate parameters which the compartmental investigation does not usually consider. These include area under the moment curve (AUMC) and mean residence time (MRT).The individual-based compartmental approach to pharmacokinetics is best carried out in the laboratory setting. Estimates of the pharmacokinetic parameters are calculated for each individual in the study. This requires obtaining many samples from each subject and hence is not suitable for the critically ill patient.Hypothesis testing and interval estimation are predicated on the underlying sampling distributions of the estimates. Without information regarding these distributions the investigator is advised to use the appropriate nonparametric statistical procedures.

Comparison of Topical Anesthetics with Lidocaine Infiltration During Laceration Repair in Children

This study is a randomized, blinded trial that compares the effectiveness of a new topical anesthetic preparation of 2% mepivacaine and 1:100,000 norepinephrine (Mepivanor); a topical solution of 1% tetracaine, 1:4,000 adrenaline, and 4% cocaine (TAC); and 1 % lidocaine infiltration during laceration repair in children. The study was conducted in the emergency department of a large academic childrens hospital. Study participants were children 2 years of age or older with a laceration on the face or scalp, 5 cm or less in length, that required suturing. Patients were randomly assigned to receive Mepivanor topical solution, TAC topical solution, or lidocaine infiltration anesthesia prior to laceration repair. Seventy-one patients were enrolled in the study during a 2-month period. Outcome measures assessed pain perceptions using a Visual Analogue Scale (VAS) and a seven-point Likert scale. There was statistical power to detect differences of 1.2 to 1.7 units for the VAS outcome measures using alpha = 0.05 and beta = 0.20. There were no statistically significant (P >0.05) differences between TAC and 1% lidocaine infiltration in providing effective anesthesia. Mepivanor was generally less effective in providing adequate anesthesia during laceration repair than TAC and lidocaine infiltration, with Tukeys post hoc test for ANOVA demonstrating statistically significant (P <0.05) differences between Mepivanor and these agents for research assistant and suture technician VAS scores. Wound blanching was judged to be less with Mepivanor than with TAC, although this difference was not statistically significant. There were no adverse reactions, wound infections, or healing difficulties for any of the patients who received TAC or Mepivanor. It was concluded that non-cocaine-containing Mepivanor was generally less effective than TAC and lidocaine infiltration in providing adequate local anesthesia during laceration repair. TAC containing only 120 mg of cocaine (3 mL of 4% cocaine) was as effective as 1% lidocaine infiltration in providing local anesthesia during laceration repair. This will allow the amount of cocaine in TAC to be reduced, thereby decreasing costs and the likelihood of adverse reactions.

The Role of Developmental and Contextual Factors in Predicting Children's Use of a Visual Analogue Scale

Our goal was to determine if age, combined with estimated IQ, is an accurate predictor of a childs successful use of a visual analogue scale (VAS) in a nonclinical situation versus an acute, clinically emergent situation. For children 5 to 11 years old, we found that the VAS is used most accurately in a nonclinical environment by children 7 years of age and older who can perform a seriation task. Estimated IQ and correct performance of a seriation task were the best predictors of 5- and 6-year-old childrens ability to use a VAS.

Prilocaine-phenylephrine topical anesthesia for repair of mucous membrane lacerations.

Objective: To compare the effectiveness of prilocaine‐phenylephrine (Prilophen), a new topical anesthetic that does not contain cocaine, to that of lidocaine infiltration during repair of lacerations on or near mucous membranes in children. Design: A prospective, randomized, blinded trial. Setting: The emergency department of a large academic childrens hospital. Patients: Children one year of age or older with a laceration 5 cm or less in length on or near a mucous membrane. Interventions: Forty patients were randomly assigned one of the two local anesthetics, with 20 patients in each treatment group. Outcome measures: Pain felt during suturing was scored by suture technicians, research assistants, a videotape reviewer, parents, and patients five years of age and older using a visual analog scale (VAS). Results: There was no statistically significant difference in performance between topical Prilophen and lidocaine infiltration when VAS pain scores of research assistants, parents, and patients were compared. However, lidocaine infiltration performed significantly better than topical Prilophen when comparing VAS scores of suture technicians (P = 0.003) and the videotape reviewer (P = 0.02). When power analyses were performed using &agr; = 0.05 and &bgr; = 0.20, it was possible to detect a difference of 2 units for VAS scores of suture technicians, 2 VAS units for research assistants, 3 VAS units for the videotape reviewer and parents, and 7 VAS units for patients. There were no wound healing or other complications. Conclusions: Prilophen is a new topical anesthetic alternative to lidocaine infiltration for closure of lacerations on or near mucous membranes, where use of tetracaine‐adrenaline‐cocaine is contraindicated. The performance of Prilophen was rated by two of the observer groups as statistically inferior to that of lidocaine infiltration; however, the differences in pain scores were small and may not be clinically significant. Further investigation of this new topical anesthetic is warranted.

The lipid composition of milk from mice fed high or low fat diets

Total fatty acids and the proportions of methyl esters of individual fatty acids were measured in mouse milk. Pregnant mice were fed either a high fat (OF) diet or a low fat (LF) diet from 14 days of gestation. After parturition, each dam was milked once a day for a period of 18 days. The mean total fatty acid concentration over the entire study period was 110 mg/g of milk (approximately 11·7% fat as triglyceride) for both dietary treatment groups. During days 2 to 6 postpartum, the mean total fatty acid concentration for dams fed OF diet was lower than for the LF group. Although the concentration of total fatty acids of mouse milk was not affected by the level of dietary fat fed to the dam, several variations in the proportions of individual fatty acids were observed.

Body weights of C3H/HeN mice fed semipurified or commercial diets of different fat content

Oncology studies often require specially formulated diets to be fed to laboratory animals. To determine the effect of dietary fat on body weight, C3H/HeN mice were carefully assigned by weight into three groups. The first group was fed a high-fat semipurified diet (23% fat by weight) from 21 to 73 days of age then returned to a low-fat semipurified diet (5% fat by weight). A second group was fed the low-fat diet from 21 to 73 days of age, then the high-fat diet until 129 days of age, then returned to the low-fat diet. A final group was fed a 4.5% fat commercial diet for the entire 193-day study. The results showed that the mice fed the semipurified diets did not differ significantly from each other in weight over the course of the study but did differ significantly between 21 and 73 days of age, possibly from a taste preference for the high-fat diet. Mice fed the commercial diet always weighed significantly less. It was estimated that mice fed the commercial diet consumed more food and were less efficient in their food utilization. Mice should be carefully assigned, by weight, into experimental groups, and all groups, including untreated controls, should be fed the same type of diet.