Dilution of rocuronium to 0.5 mg/mL with 0.9% NaCl eliminates the pain during intravenous injection in awake patients

In a randomized, double-blinded, controlled study, we evaluated the effect of diluting rocuronium 10 mg/mL to 1 or 0.5 mg/mL with 0.9% NaCl on the pain associated with IV administration of rocuronium with small doses given before succinylcholine or nondepolarizing agent administration. One hundred fifty patients undergoing surgical procedures that required general anesthesia were randomized into three groups. Group 1 received rocuronium 10 mg/mL. Groups 2 and 3 received 1 and 0.5 mg/mL of rocuronium, respectively. Patient demographics, pain scores, osmolality, and the pH of the solutions were recorded. Group 1 had the most intense and frequent pain response. Eighty percent of patients in this group reported pain on injection. In Group 2, the incidence and intensity of pain were significantly less when compared with those of Group 1. In this group, 38% of patients reported pain during injection. In Group 3, none of the patients experienced pain on injection. The pH values and osmolalities of study solutions were not significantly different among groups. In conclusion, in awake patients, dilution of rocuronium 10 mg/mL at small doses given before succinylcholine or nondepolarizing agent administration of 0.06 mg/kg to 0.5 mg/mL with 0.9% NaCl is a simple and cost-effective strategy for preventing pain during IV rocuronium injection.     

Bistable firing properties of soleus motor units in unrestrained rats

EMG recordings from single motor units in the soleus muscle were performed in alert unrestrained rats. A cuff electrode around the tibial nerve and subcutaneously placed electrodes in the foot permitted stimulation of afferent fibres. The movements of the rat and the simultaneous EMG activity were displayed together on a video monitor. Most motor units were tonically active for extended periods during quiet standing. During tonic discharge, maintained shifts between stable low (8-12 Hz; quartiles) and high (16-22.8 Hz) frequency ranges were initiated by short-lasting synaptic excitation of the motoneuron pool by stimulation of Ia afferents, or inhibition by stimulation of skin afferents. The shifts were not related to gross limb movements. This phenomenon is referred to as a bistable firing pattern. Bistable firing also occurred spontaneously during quiet standing. Typically the firing frequency shifted between a low (9-12.5 Hz) and a high (20-24.5 Hz) mode. During recordings of simultaneous activity in two units, spontaneous and stimulus-induced frequency jumps causing maintained changes in firing frequency were regularly seen to occur in one unit, while the frequency in the second unit was unchanged or only phasically influenced. These results demonstrate for the first time a bistable firing pattern during postural activity in the intact animal. The firing pattern closely resembles the bistable behaviour described in spinal motoneurons in reduced preparations, where it is due to the presence of a plateau potential. This suggests that the bistable firing is unexplained by plateau potentials also in the intact animal.     

The importance of frequency and amount of electrical stimulation for contractile properties of denervated rat muscles.

Soleus (SOL) and extensor digitorum longus (EDL) muscles were denervated and directly stimulated for 23-69 days through implanted electrodes employing three different patterns. The stimulation was delivered in impulse trains where the pulse frequency differed (20, 75, and 150 Hz), while the train duration (0.3 s) and train repetition rate (1 min-1) were identical. Consequently, the number of pulses varied such that higher frequency was combined with a higher amount of stimulation. In both SOL and EDL the high-frequency pattern resulted in shorter twitch time-to-peak, greater post-tetanic potentiation, and greater tetanic force than the low frequency. Isotonic shortening velocity was increased to the same extent by all the patterns in SOL whereas in EDL fast intrinsic shortening velocity was maintained by the low-frequency pattern while it was decreased by the high-frequency pattern. We attribute this unexpected effect on the EDL to the larger number of pulses in the high-frequency pattern. By combining the present findings with previous data on directly stimulated rat muscles we conclude: in SOL the twitch duration is influenced by both the frequency and the amount of impulse activity, higher frequencies and smaller amounts leading to faster twitches. The EDL twitch duration is similarly dependent on the amount of activity, but the role of frequency is more unclear. In both SOL and EDL the isotonic shortening velocity is reduced by increasing amounts of activity and there is no evidence that impulse frequency plays a role. In EDL force output is strongly influenced by the impulse frequency, low frequencies resulting in low force outputs irrespective of the amount of activity.     

Oxidative stress and antioxidant defense in patients with chronic hepatitis C patients before and after pegylated interferon alfa-2b plus ribavirin therapy

Background  

Oxidative stress could play a role in pathogenesis of hepatitis C virus (HCV) infection. The aim of our study is to determine oxidant/antioxidant status of patients with chronic hepatitis C (CHC), and the effect of pegylated interferon alfa-2b plus ribavirin combination therapy on oxidative stress.     

Amplitude integrated EEG 3 and 6 hours after birth in full term neonates with hypoxic-ischaemic encephalopathy.

AIM: To assess the prognostic value of amplitude integrated EEG (aEEG) 3 and 6 hours after birth. METHODS: Seventy three term, asphyxiated infants were studied (from two different centres), using the Cerebral Function Monitor (CFM Lectromed). The different aEEG tracings were compared using pattern recognition (flat tracing mainly isoelectric (FT); continuous extremely low voltage (CLV); burst-suppression (BS); discontinuous normal voltage (DNV); continuous normal voltage (CNV)) with subsequent outcome. RESULTS: Sixty eight infants were followed up for more than 12 months (range 12 months to 6 years).Twenty one out of 68 infants (31%) showed a change in pattern from 3 to 6 hours, but this was only significant in five cases (24%). In three this changed from BS to CNV with a normal outcome. One infant showed a change in pattern from CNV to FT and had a major handicap at follow up. Another infant showed a change in pattern from DNV to BS, and developed a major handicap at follow up. The other 16 infants did not have any significant changes in pattern: 11 infants had CLV, BS, or FT at 3 and 6 hours and died (n = 9) in the neonatal period or developed a major handicap (n = 2). Five infants had a CNV or DNV pattern at 3 and 6 hours, with a normal outcome. The sensitivity and specificity of BS, together with FT and CLV, for poor outcome at 3 hours was 0.85 and 0.77, respectively; at 6 hours 0.91 and 0.86, respectively. The positive predictive value (PPV) was 78% and the negative predictive value (NPV) 84% 3 hours after birth. At 6 hours the PPV was 86% and the NPV was 91%. CONCLUSION: aEEG could be very useful for selecting those infants who might benefit from intervention after birth asphyxia.     

The effects of hyperbaric oxygen treatment on oxidative stress and SCE frequencies in humans

OBJECTIVES: Hyperbaric oxygen (HBO) therapy is a useful method for treatment of various clinical conditions but it can also cause an increased production of free radicals and oxidative DNA damage. In this study, our aim was to investigate the effects of hyperbaric oxygen on oxidative stress and genetic toxicity. DESIGN AND METHODS: Fifteen patients were exposed to HBO treatment for various pathologies related to hypoxia. Blood samples were taken before HBO therapy and at the end of the 1st, 10th and 20th HBO sessions. Antioxidant parameters and genetic toxicity were studied. RESULTS: We have observed that an increment of lymphocyte sister chromatid exchange (SCE) frequency was detected at the end of the 1st, 10th and 20th HBO sessions compared to before HBO treatment (P<0.05). No significant difference in erythrocyte copper-zinc superoxide dismutase (CuZn-SOD), selenium dependent glutathione peroxidase (SeGSH-Px) and malondialdehyde (MDA) levels were observed at the end of the 1st HBO therapy and the prolonged HBO exposure as compared to before HBO treatment (P>0.05). CONCLUSIONS: Our results indicate that HBO treatment did not cause significant changes on erythrocyte antioxidant capacity and lipid peroxidation; however, it could induce genotoxicity due to different mechanisms.     

In acute organophosphate poisoning, the efficacy of hemoperfusion on clinical status and mortality

The aims of this study were to report experience in patients with organophosphate poisoning (OPP) and to discuss the potential role for hemoperfusion (HP) in the management of severe OPP. At the emergency service of a university hospital, 52 patients with acute OPP were included in this retrospective study. The patients were divided into 2 groups (Group 1, severe poisoning, n = 25; and Group 2, mild poisoning, n = 27). All patients with mild OPP survived. Seven patients (28%) of the 25 with severe OPP died. This study supports previous data documenting that HP is unnecessary in the management of mild OPP. Although there was not a control group (severe poisoning without HP treatment) in this study, experience suggests that HP can be useful in severe cases. Reports from centers having experience with severe OPP can help clarify this controversial issue. Randomized controlled (prospective) studies investigating the possible beneficial effects of HP on patient survival in patients with severe OPP with control group are needed.     

The impact of patient volume on surgical trauma training in a Scandinavian trauma centre

OBJECTIVE: Some of the problems faced in trauma surgery are increasing non-operative management of abdominal injuries, decreasing work hours and increasing sub-specialisation. We wanted to document the experience of trauma team leaders at the largest trauma centre in Norway, hypothesising that the patient volume would be inadequate to secure optimal trauma care. METHODS: Patients registered in the hospital based Trauma Registry during the 2-year period from 1 August 2000 to 31 July 2002 were included. RESULTS: Of a total of 1667 patients registered, 645 patients (39%) had an Injury Severity Score (ISS)>15. Abdominal injuries were diagnosed in 205 patients with a median ISS of 30. An average trauma team leader assessed a total of 119 trauma cases a year (46 patients with ISS>15) and participated in 10 trauma laparotomies. CONCLUSION: Although the total number of trauma cases seems adequate, the experience of the trauma team leaders with challenging abdominal injuries is limited. With increasing sub-specialisation and general surgery vanishing, fewer surgical specialties provide operative competence in dealing with complicated torso trauma. A system of additional education and quality assurance measures is a prerequisite of high quality, and has consequently been introduced in our institution.