Force models for needle insertion created from measured needle puncture data.

The focus of this paper is to present a force-feedback model that has been developed for the epidural needle insertion procedure. The model is based on data collected from biomaterials testing studies, and consists of separate force models for each of the tissue types relevant to the epidural needle insertion procedure. These tissue force models were generalized to create force-feedback models to drive haptic devices for needle insertion simulation.

Relationship between physiological factors and clinical pain in dogs scored using a numerical rating scale.

A study was designed to investigate the association between heart rate, respiratory rate and pupil dilation and a subjective pain score allocated using a numerical rating scale (NRS). Four groups of dogs (n = 17 to 20 per group) were included: orthopaedic surgery cases, soft tissue surgery cases, dogs with medical conditions and healthy dogs. Each dog was examined by five veterinary surgeons within a four-hour period. When examining each dog, the observers recorded heart rate, respiratory rate, pupil dilation (present or absent) and a pain score using a NRS (range 0 to 10). For surgical cases, all study assessments were carried out between 21 and 27 hours following the end of surgery. The correlation coefficients between physiological parameters and NRS score were small but, depending on the analysis, were significant for heart rate and NRS score (P < 0.05). However, the size of the coefficient, 0.168, indicated that the relationship was not biologically significant. There was no association between respiratory rate and NRS score. Analysis of the relationship between NRS score and pupil dilation indicated that there was an association between this factor and pain, depending on the analysis. This was significant for the surgical groups (P < 0.05) but not for the other groups. These findings indicate that heart rate and respiratory rate are not useful indicators of pain in hospitalised dogs. It is also unlikely that pupil dilation will be a useful tool in the assessment of pain.

Comparison of three methods used for assessment of pain in dogs.

OBJECTIVE: To investigate the reliability of 3 scales used for assessment of pain in dogs. DESIGN: Prospective study. ANIMALS: 50 dogs that had surgery. PROCEDURE: Dogs were allocated into 3 groups (group 1, 25 dogs assessed 1 hour after the end of surgery; group 2, 41 dogs assessed between 21 and 27 hours after the end of surgery; group 3, 16 dogs assessed on the day of surgery and on the subsequent day). Each dog was scored for pain 4 times by 3 (groups 1 and 3) or 4 (group 2) veterinarians, using all 3 scales (i.e. simple descriptive, numerical rating, and visual analogue) during each scoring period. Analysis of data was performed using ANOVA, log-linear modeling, calculation of reproducibility coefficients, and Cohen's kappa statistic. RESULTS: Significant variability existed among observers for use of all 3 scales. Variability among observers and between observers and dogs accounted for 29 to 36% of the total variability (group 1, 36.1 and 32.3% and group 2, 35.1 and 29.7%, for visual analogue scale and numerical rating scale scores, respectively). Kappa statistic values calculated for data obtained by use of the simple descriptive scale indicated that agreement was fair for the observers (group 1, 0.244 to 0.299; group 2, 0.211 to 0.368; group 3, 0.233 to 0.321). CLINICAL IMPLICATIONS: Analysis of pain score data in dogs must incorporate observer variability when more than 1 observer is used. Comparative analysis of data accrued from pain studies in various hospitals must account for this variability.