Long term effects of diving

Aims and Background: We tested the hypothesis that repeated hyperbaric O2 preconditioning (HBO-PC) may have a protective effect against CNS oxygen toxicity (CNS-OT) in the rat. Methods: The rats in control group 1 (C1) were kept in normobaric air together with five sham rats. Rats in the experimental group and control group 2 (C2) were exposed to HBO at 202 kPa for 1 h as preconditioning once every other day for a total of three sessions. Twenty-four hours after preconditioning, the rats in both the experimental and C1 groups were exposed to 608 kPa. We measured the latency to CNS-OT, after which all of the animals were sacrificed and tissues were harvested from the hippocampus and frontal cortex for biochemical examination. Results: Time to CNS-OT increased significantly following preconditioning. There was a 20%, statistically significant increase in the activity of glutathione-S-transferase (GST) and glutathione-peroxidase (GP) in the cortex of the preconditioned rats. Nitrotyrosine levels in the cortex did not demonstrate any significant trend. In the hippocampus of the preconditioned rats, a significant decrease was found in the activity of glutathionereductase (GR) and G6PD, whereas there was a significant increase in the activity of GP. Nitrotyrosine levels in the hippocampus demonstrated the same trend in all five marked proteins. The highest levels were found in the C1 group, whereas the lowest levels were found in the experimental group. Conclusions: This study demonstrates that under well defined conditions, repeated exposure to HBO may have a preconditioning effect, providing protection against CNS-OT. The protective mechanism involves alterations in the enzymatic activity of ROS scavengers induced by HBO exposure, mainly in the hippocampus. These alterations result in lower levels of distractive RNS (and probably ROS) and prolonged latency. NONINVASIVE EVALUATION OF SYSTEMIC HEMODYNAMIC AND MICROCIRCULATORY RESPONSE TO HBO IN MECHANICALLY VENTILATED INTENSIVE-CARE PATIENTS Ledoux-Houcke S, Ratzenhofer-Komenda B, Salleron J, Favory R, Juille JL, Mathieu D Service d’Urgence Respiratoire de Réanimation Médicale et de Médecine Hyperbare, Hôpital Calmette, Centre Hospitalier Régional et Universitaire de Lille, CHRU Lille, 59037 Lille Cedex, France Dept of Anaesthesia and Intensive Care Medicine, University Medical School of Graz, LKH-Universitätsklinikum, Auenbrugger Platz 29, A-8036 Graz, Austria Aims: The study aimed at observing the the behaviour of microvascular perfusion and systemic hemodynamics in ventilated and sedated ICU patients before, during and after HBO therapy, at determining the correlation between microand macrocirculation with regard to elevated ambient pressure, and at recording the catecholamine demand during the study period. Patients and methods: Inclusion criteria: routine HBO treatment according to the disease, stable hemodynamic condition without modification of the treatment within 6 h before the session. After approval by the local ethics committee, 10 mechanically ventilated and sedated ICU patients (Ramsay Sedation Scale grading 5-6) undergoing routine HBO therapy were enrolled in this prospective observational study. Patient data: 4f, 6m, mean age: 60 yr; diagnosis: cellulitis in 8 pts., acute cerebral hypoxia in 2 pts, catecholamine support in 4 pts. The following parameters were obtained every 5-10 min at 30 min before treatment , during a stabilization phase of 15 min after transport to the chamber with normobaric oxygen breathing(NBO), during and until 90 min, and at 120, 150 and 180 min after the session: standard monitoring of heart rate (HR), arterial blood pressure, central venous pressure (CVP), peripheral oxygen saturation (SaO2), cardiac output (thoracic bioimpedance), and, in the subclavian region, transcutaneous oxygen (tcPO2) and carbon dioxide (tcPCO2) tension, microvascular perfusion (flux, laser-Doppler flowmetry). Routine arterial blood gas sampling at 1 h after the session. HBO protocol: 252.5 kPa, 90 min. Statistics: linear mixed model , Wilcoxon rank test. P< 0.05 = significant. Results: Macrocirculation: HR declined significantly by 4.6% after transport to the chamber (p= 0.041), afterwards no significant difference. No change of blood pressures and cardiac output. Microcirculation: Significant change of tcPO2 with inspired oxygen pressures (p< 0.0001), no change of tcPCO2 and flux. Correlation coefficient between cardiac output and flux: 0.43 (P= 0.0007), no correlation between flux and tcPO2. Significant mean decline of arterial oxygen tension by 10.1 % (P= 0.0039) after the session. No increased catecholamine demand during and after the session. Discussion and conclusion: The exposure to HBO was well tolerated by hemodynamically stable ventilated intensive-care patients. In our collective, there was a positive correlation between laser Doppler flowmetry flux values and bioimpedance-based cardiac output values, contarily to the flux-tcPO2 interrelationship. The early postsessional decline of arterial PO2 might be attributed to atelectasis formation and is likely to be reversible by applying a recruitment maneuver. This study was created within the frame of the COST B14 action on hyperbaric medicine. HYPERBARİC OXYGEN THERAPY USED TO TREAT CHRONİC RADİATİON PROCTİTİS Maide Cimsit, Abdullah Arslan, Yavuz Dizdar, Selva Mert 1 Department of Underwater and Hyperbaric Medicine, Istanbul Faculty of Medicine, Istanbul University 2 Institute of Radiation Oncology Aims: To evaluate the effects of hyperbaric oxygen therapy (HBOT) in chronic radiation proctitis (CRP) which is refractory to conventional therapies. Introduction: CRP is a late complication of pelvic radiotherapy which occurs after a latent period. In general incidence is reported as less than 5% (1,2). CRP is progressive by its nature and can be devastating. Clinical presentations are pain, urgency and diarrhea, constipation, tenesmus, mucoid or bloody discharge, bleeding or combination of these. There is no standard treatment exist, and the results of conventional treatment are poor. HBOT has been used in recent years for treatment of CRP and reported to be beneficial (3,4). Methods: Present study reports the results of 7 cases of CRP who were non-responding to conventional treatment and referred to our center for HBOT between the years of 2001-2009. Patients’ diagnosis was confirmed by endoscopy before initiating the HBOT. HBOT was given once a day, 5 days in a week. 6 patients received HBOT in a monoplace chamber. Treatment protocol was 100% O2 for 90 minutes at 2.1 ATA. One patient treated in a multiplace chamber at 2.4 ATA, as three 25 minutes periods of 100% O2 dispersed by 5 minutes of air breaks. Results: The mean age of the patients (4 male, 3 female) was 63.5 (range 50-75). Common complaints were pain, frequency,diarrhea, bloody discharge, tenesmus and occasional bleeding. The primary diagnosis were prostat carcinoma in 4 cases, others were rectal carcinoma, endometrial carcinoma and malign melanoma. Pelvic radiotherapy doses were minimum 45 Gy, maximum 73.8 Gy. The mean latent period was 5.5 months (range 2-11). The mean number of total HBOTs were 40. Endoscopic evaluation performed after completion of HBOT showed significant healing in 5 and partial improvement in two patients. All patients were free of pain. Frequency and diarrhea absent in 6, and bloody discharge stopped in 5 patients. 5 patients (%71) discharged with complete healing and two patients with partial improvement. No complications developed due to HBOT. Discussion: Though this study is a retrospective and non-controlled one and number of patients are few, clinical and laboratory results of this study emphasize that HBOT can be effectively used for the treatment of refractory chronic radiation proctitis.