ABSTRACT
BACKGROUND: There is a suggestion that tissue acidosis may contribute to the induction of pain in inflammation and ischemia. High local proton concentrations have been found in painful inflammatory and ischemic conditions. We assessed tissue pH and pain behavior in a rat model for postoperative pain. METHODS: An incision of skin, fascia, and muscle was performed in the right foot. Pain behaviors to von Frey, blunt probe stimulation, and resting pain were evaluated on the incised feet. Then tissue pH was measured in each of the five rats at 4 hours, 1, 2, 4, and 7 days after incision. RESULTS: The withdrawal threshold to von Frey was decreased, the response frequency to blunt probe and pain scores were elevated from 4 hours to 1 - 2 days after the incision. The deep tissue pH decreased from pH 7.16 in sham to pH 6.95, 6.90, 6.89, and 6.95 at 4 h and 1, 2, and 4 days after incision respectively. CONCLUSIONS: In this study, the tissue pH of the wound decreased after surgery. However, the change of tissue pH was not always consistent with pain behaviors. Our results suggest that tissue acidosis may relate partially to the induction of pain after tissue injury.
Subject(s)
Animals , Rats , Acidosis , Acute Pain , Fascia , Foot , Hydrogen-Ion Concentration , Inflammation , Ischemia , Models, Animal , Pain, Postoperative , Protons , Skin , Wounds and InjuriesABSTRACT
BACKGROUND: A Stellate ganglion block (SGB) is a sympathetic nerve block method which has been used most frequently in pain clinics due to its wide range of indications. However, SGB leads to regional sympathetic denervation of the heart and to changes in the hemodynamics. The aim of this study was to compare hemodynamic effects as well as echocardiographic changes after a left SGB (LSGB). METHODS: Fourteen healthy male volunteers were studied. The LSGB was performed with 1% mepicacaine 6 ml. Arterial blood pressure, electrocardiographic and echocardiographic variables were measured before the LSGB, 15 and 30 minutes after the LSGB. RESULTS: Arterial blood pressure, ejection fraction and transmitral inflow velocity variables showed no significant changes compared to pre-LSGB values. P-P interval increased significantly 15 minutes after the LSGB, and the Q-T interval increased significantly 30 minutes after the LSGB. The diastolic pulmonary venous flow velocity decreased significantly 15 minutes after the LSGB. CONCLUSIONS: These results showed that a LSGB decreased the heart rate without detrimental changes of left ventricular relaxation in healthy male volunteers.