BACKGROUND: Distal ulnar nerve injury leads to impairment of hand function due to motor and sensorial changes. Stimulus electrodiagnosis (SE) is a method of assessing and monitoring the development of this type of injury. OBJECTIVE: To identify the most sensitive electrodiagnostic parameters to evaluate ulnar nerve recovery and to correlate these parameters (Rheobase, Chronaxie, and Accommodation) with motor function evaluations. METHOD: A prospective cohort study of ten patients submitted to ulnar neurorrhaphy and evaluated using electrodiagnosis and motor assessment at two moments of neural recovery. A functional evaluation using the DASH questionnaire (Disability of the Arm, Shoulder, and Hand) was conducted at the end to establish the functional status of the upper limb. RESULTS: There was significant reduction only in the Chronaxie values in relation to time of injury and side (with and without lesion), as well as significant correlation of Chronaxie with the motor domain score. CONCLUSION: Chronaxie was the most sensitive SE parameter for detecting differences in neuromuscular responses during the ulnar nerve recovery process and it was the only parameter correlated with the motor assessment.

CONTEXTUALIZAÇÃO: A asssistência ventilória mecânica (AVM) prolongada associada a altas frações de oxigênio produz impacto negativo na função diafragmática. No entanto, não são claros os efeitos agudos da AVM associada a altas frações de oxigênio em pulmões aparentemente sadios. OBJETIVO: Analisar os efeitos agudos da ventilação mecânica com hiperóxia na morfometria do diafragma de ratos. Métodos: Estudo experimental prospectivo, com nove ratos Wistar, com peso de 400±20 g, randomizados em dois grupos: controle (n=4), anestesiados, traqueostomizados e mantidos em respiração espontânea em ar ambiente por 90 minutos e experimental (n=5), também anestesiados, curarizados, traqueostomizados e mantidos em ventilação mecânica controlada pelo mesmo tempo. Foram submetidos à toracotomia mediana para coleta da amostra das fibras costais do diafragma que foram seccionadas a cada 5 μm e coradas pela hematoxilina e eosina para o estudo morfométrico. Para a análise estatística, foi utilizado o teste t de Student não pareado, com nível de significância de p<0,05. RESULTADOS: Não foram encontrados sinais indicativos de lesão muscular aguda, porém observou-se dilatação dos capilares sanguíneos no grupo experimental. Os dados morfométricos do diâmetro transverso máximo da fibra muscular costal foram em média de 61,78±17,79 µm e de 70,75±9,93 µm (p=0,045) nos grupos controle e experimental respectivamente. CONCLUSÃO: A ventilação mecânica de curta duração com elevada concentração de O2 produziu marcantes alterações microvasculares e musculares, podendo refletir o início do processo inflamatório.

BACKGROUND: Prolonged mechanical ventilatory support (MVS) combined with high oxygen concentrations has a negative impact on diaphragm function. However, the acute effects of MVS with hyperoxia have not been elucidated. Objective: To analyze the acute effects of mechanical ventilation with hyperoxia on the morphometry of the rat diaphragm. METHODS: An experimental, prospective study was conducted with Wistar rats (weight: 400±20 g), which were randomly allocated to two groups. The control group (n=4) was anesthetized, tracheostomized and kept spontaneously breathing room air for 90 minutes. The experimental group (n=5) was also anesthetized, curarized, tracheostomized and kept in controlled mechanical ventilation for the same amount of time. Both groups were submitted to median thoracotomy for sample collection of costal fibers from the diaphragm muscle, which were sectioned every 5 μm and stained with hematoxylin and eosin for the morphometric study. Independent Student's t tests were employed to investigate differences between groups, with a significance level of p<0.05. RESULTS: There were no signs of acute muscle lesions, however the blood capillaries became dilated in the experimental group. The mean morphometric data related to the maximum cross-sectional diameter of the diaphragm costal fibers were 61.78 ±17.79 µm and 70.75±9.93 µm (p=0.045) for the control and experimental groups, respectively. CONCLUSIONS: Short-term mechanical ventilation with hyperoxia led to significant microvascular and muscle changes, which may reflect the onset of an inflammatory process.