Temporal variation of oxidant stress in critically ill patients.

AIM: Our aim was to investigate indicators of lipid peroxidation via observing temporal changes or daily fluctuations in cytoprotective enzymes such as superoxide dismutase (SOD) and glutathione peroxidase (GSH-PX), and serum components possessing antioxidant activity against free radicals and malondialdehyde (MDA) such as uric acid. This study was conducted in a small number of critically ill patients versus healthy volunteers in order to design an effective antioxidant therapy regimen under oxidative stress. METHODS: Six critically ill patients and 6 young healthy volunteers were recruited. Blood samples were collected 6 times a day with 4 h intervals starting from 8 a.m. From the blood samples, SOD and GSH-PX activities and uric acid and MDA levels were determined. One-way ANOVA and unpaired t-test were used to assess differences within and between the groups, respectively. A two dimensional table curve cosine formulation was performed to elucidate rhythmycity. RESULTS: No significant differences were found in SOD and GSH-PX activities or uric acid levels within the 24 h period or between the groups. MDA levels were significantly higher in the study group at 8 p.m. than that of control group (P<0.05), but no significant difference was found within the 24 h period. We showed that GSH-PX activities in control and study groups revealed temporal variation, whereas uric acid levels varied temporally only in the study group. CONCLUSION: We concluded that there are signs of oxidative stress in ICU patients that vary in time but further studies are required in order to design appropriate antioxidant treatments.

Relief of posttonsillectomy pain with low-dose tramadol given at induction of anesthesia in children.

OBJECTIVE: Pain is major problem regarding quality of life in children undergoing tonsillectomy. Preemptive analgesia by medicine given before commencement of surgery is a new way recommended for relief of pain during and after operation. The purpose in this study to evaluate preemptive efficacy and safety of lower dose of tramadol, which was recently introduced in children undergoing tonsillectomy. METHODS: This study was performed on 45 children undergoing tonsillectomy with or without adenoidectomy as a double-blinded trial, by using tramadol in two dosages (1 and 0.5 mg kg(-1)) and placebo. Pain assessment was done by facial pain score (FPS), visual analog scale (VAS) and postoperative analgesic requirement; further, duration of anesthesia and duration of awakening time, heart rate (HR) and mean arterial pressure (MAP) during and after anesthesia, postoperative nausea and vomiting (PONV) and recall of intraoperative events were recorded. RESULTS: It was found that 73% children in placebo group needed analgesic medicine at the end of the first hour after operation, although no analgesic medicine was needed in tramadol groups (chi(2) test, P<0.001). However, statistically significant decrease in FPS and VAS in tramadol groups were only found up to 15th and 30th min after operation, respectively (Kruskall-Wallis test, P<0.05). On the other hand, intraoperative HR (10th, 20th and 30th min) and MAP (10th and 20th min) were found to be higher in placebo groups (ANOVA variance analysis, Tukey-Kramer test adjusted paired t-test, P<0.001 and <0. 01, respectively). No significant difference was found in the other parameters, and no surgical complication and adverse side effect were occurred in this number of study sample. CONCLUSION: Tramadol in lower doses (0.5-1 mg kg(-1)) was an efficient preemptive analgesic that could be used at induction of anesthesia in adenotonsillectomies of children for providing both good analgesia during operation as supplementation to propofol anesthesia and postoperative analgesia in only early period.

Pulmonary microvascular injury following general anaesthesia with volatile anaesthetics--halothane and isoflurane: a comparative clinical and experimental study.

Pulmonary microvascular injury has become a recently studied phenomenon that may be responsible for most of the complications associated with the lungs. Thirty patients undergoing partial hemilaminectomy or discectomy due to hernia of nucleus pulposus underwent Tc-99m HMPAO lung clearance as well as Tc-99m pertechnetate lung scintigraphy pre-operatively, and following general anaesthesia with halothane and isoflurane (third, fourth and tenth post-operative days). The results were compared with conventional techniques and haemodynamic parameters during the peri-operative period. In order to demonstrate acute phase changes under general anaesthesia and to perform pathological examinations, 21 New Zealand rabbits underwent radionuclide studies with Tc-99m HMPAO or Tc-99m pertechnetate. Lung biopsies were also performed. Despite no significant differences in any of the conventional diagnostic techniques, Tc-99m pertechnetate lung scintigraphy was performed for both the halothane and isoflurane groups, and Tc-99m HMPAO lung clearance was performed for the isoflurane group pre- or post-operatively. Tc-99m HMPAO lung clearance was impaired significantly in the halothane group on the third post-operative day (half time: 6.4 +/- 1.6 pre-operative and 13.76 +/- 3.3 s, P < 0.001) decreasing to pre-operative levels on the tenth post-operative day. Acute phase exposure to halothane was characterized with extremely abnormal Tc-99m HMPAO lung clearance in rabbits with respect to isoflurane, diminishing to control levels on the third day (half time: 8.7 +/- 86 control and 28.65 +/- 4.6, P < 0.001). Pathological examinations also demonstrated endothelial damage on acute exposure in the halothane group. General anaesthesia with halothane may give rise to alveolar microvascular injury, which generally seems to be underdiagnosed and may lead to serious post-operative complications.

Perineural pethidine: effects of different doses on nerve conduction.

Forty healthy young volunteers were divided randomly into four equal groups. 2 ml of solutions of pethidine (meperidine) in concentrations of 0.5%, 1% and 1.5% were given to three groups of 10 subjects: a fourth group received saline. Sensory evoked responses obtained via surface electrodes from both sural nerves simultaneously in the pethidine groups and unilaterally in the control group, were evaluated for latency, conduction velocity and amplitude. Sensory changes at the innervation zone were monitored by means of a pinprick. All recordings were obtained prior to injection and at 5 min intervals for 30 min. Concentrations of 1% and 1.5% pethidine were associated with significantly lower amplitudes and with hypoalgesia. Other parameters did not change.

Effects of perineural opioids on nerve conduction of N. suralis in man.

In this study the effects of agonist acting drugs (morphine sulphate, fentanyl citrate and meperidine hydrochloride) on nerve conduction were studied in 43 healthy young volunteers divided into four groups randomly. According to analgesic equivalent doses, the first group received 2 mg morphine sulphate, the second group 0.02 mg fentanyl citrate, the third group 20 mg meperidine hydrochloride, and as control the fourth group received 2 ml of saline. The latencies, amplitudes of the responses and nerve conduction velocities were obtained immediately before and every 5 min after injections up to 30 min. No significant change was observed within or among the morphine sulphate, fentanyl citrate and saline groups whereas in the meperidine hydrochloride group the amplitudes diminished significantly and this finding was still apparent at 30 min. Four of the cases displayed complete blocks. Nerve conduction velocity did not change in the other 6 cases. The significant decrement of the amplitude of the compound nerve action potential in the meperidine hydrochloride group is probably due to local anesthetic-like action of this drug. Morphine sulphate, fentanyl citrate or saline did not show this effect.

The histopathological comparison of the results of the intra-arterial injections of propofol and thiopentone in rabbits.

The results of injections of propofol and thiopentone intra-arterially are compared in rabbits according to histopathological criteries. Thirteen New Zealand type rabbits are used. Two ml of 2.5% Thiopentone and 2 ml of 1% Propofol are administered to the rabbits under anesthesia. Three days after, their ears are amputated and sent to this pathological blind examination. In both groups, we saw neither a morphological change along the vessel walls nor significant bleeding. But between the groups there was a significant difference about oedema. Consequently, 2.5% thiopentone which is routinely used after intra-arterial administration, may be responsible of the gangrenous change but it is discussable and it makes significant oedema in animal models although propofol does not have this effect.