Senol Yildiz

Hyperbaric oxygen therapy as an anti-infective agent

Hyperbaric oxygen therapy (HBOT) involves inhalation of 100% oxygen at supra-atmospheric ambient pressure. HBOT is used as either a primary or adjunctive treatment in the management of infections such as gas gangrene, necrotizing fasciitis, diabetic foot infections, refractory osteomyelitis, neurosurgical infections and fungal infections. HBOT acts as a bactericidal/bacteriostatic agent against anerobic bacteria by increasing the formation of free oxygen radicals. HBOT restores the bacterial-killing capacity of leukocytes in hypoxic wounds by increasing tissue oxygen tensions. In addition, HBOT acts synergistically with a number of antibiotics. This article reviews the anti-infective effects of HBOT and the use of HBOT in the treatment of certain infectious diseases.

Effects of Different Doses of Hyperbaric Oxygen on Cisplatin-Induced Nephrotoxicity

Cisplatin, an effective antineoplastic agent, frequently induces acute renal failure in animals and humans. Hyperbaric oxygen (HBO) has been shown to prevent cisplatin-induced nephrotoxicity in rats. This study investigated the effect of two different HBO regimes on renal functions, oxidative stress, and histopathological changes in rat kidneys after cisplatin treatment. Wistar rats were divided into five groups: control, HBO, cisplatin, cisplatin plus once daily HBO, and cisplatin plus twice daily HBO. Cisplatin was given as a single intraperitoneal dose of 6 mg/kg, and HBO was applied for 60 min at 2.5 atm for six days. HBO alone did not alter any biochemical parameters or histopathological findings compared with the control group. Cisplatin increased serum urea and creatinine levels and caused severe histopathological injury. In addition, cisplatin increased lipid peroxidation and impaired superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activities in kidney tissue. Once daily HBO after cisplatin treatment slightly reduced serum urea and creatinine levels and attenuated histopathological injury. HBO also reduced lipid peroxidation and increased SOD and GSH-Px activities significantly. Although twice daily HBO was determined to be more effective than once daily HBO on oxidative stress parameters, it increased serum creatinine levels and histopathological injury compared with the cisplatin group. It was concluded that HBO alone does not induce nephrotoxicity and oxidative stress in rat kidneys; once daily HBO may prevent cisplatin-induced nephrotoxicity, an effect that is partially mediated by the modification of oxidant/antioxidant systems in the kidneys; and twice daily HBO potentiates cisplatin nephrotoxicity by a ROS-independent mechanism.

Long-term exposure to repetitive hyperbaric oxygen results in cumulative oxidative stress in rat lung tissue

Context: Despite its known benefits, hyperbaric oxygen (HBO) is also reported to enhance the production of reactive oxygen species and can cause oxidative stress in several tissues. Previous studies had shown that HBO-induced oxidative stress is directly proportional to both its exposure pressure and duration. Nevertheless, these studies were usually performed with single-session HBO exposure but its clinical use commonly depends on long-term exposure periods. Objective: To clarify the oxidative effect of long-term repetitive HBO in the lung tissue of rats. Materials and methods: Male Sprague-Dawley rats were divided into six study groups exposed to consecutive HBO sessions (2.8 atm/90 min) for 5, 10, 15, 20, 30, and 40 days. Animals were sacrificed 24 h after the last HBO session. An additional control group was set to obtain normal data. Lung malondialdehyde (MDA) and carbonylated protein (PCC) levels were determined as measures of oxidative stress along with the activities of the antioxidant enzymes superoxide dismutase (SOD) and glutathione peroxidase. Results: None of the measured parameters showed any changes among the groups exposed to 5–15 HBO sessions. However, MDA, PCC, and SOD were found to be significantly increased in the 20 to 40 session groups. Discussion and conclusion: These results indicate that repetitive treatment with HBO may cause oxidative stress in critical tissues including the lung. Although HBO-mediated free radicals are accepted to be responsible for the benefits of this therapeutic modality, especially in cases with prolonged exposure, possible injurious effects of supranormal values of bio-oxidative products need to be considered.

Cerebral white-matter lesions in asymptomatic military divers.

INTRODUCTION There is some concern that over a period of years, diving may produce cumulative neurological injury even in divers who have no history of decompression sickness. We evaluated asymptomatic divers and controls for cerebral white-matter lesions using magnetic resonance imaging (MRI). METHODS The study enrolled 113 male military divers (34.4 +/- 5.6 yr) and 65 non-diving men (33.1 +/- 9.0 yr) in good health. Exclusion criteria included any condition that might be expected to produce neurological effects. Patent foramen ovale was not assessed. A questionnaire was used to elicit diving history. A 1.5-T MRI device was used to acquire T1, T2-weighted, and fluid attenuated inversion recovery (FLAIR) images of the brain. A lesion was counted if it appeared hyperintense on both T2-weighted and FLAIR images. RESULTS MRI revealed brain lesions in 26 of 113 divers (23%) and in 7 of 65 (11%) controls, a difference that was statistically significant. There was no significant difference between the groups with respect to blood pressure, smoking history, or alcohol consumption, and no subject reported a history of head trauma or migraine. There was no relationship between MRI findings and age, diving history, or lipid profile in divers. DISCUSSION The higher incidence of lesions in the cerebral white matter of divers confirms the possibility that cumulative, subclinical injury to the neurological system may affect the long-term health of military and recreational divers.

Performance of the probe-to-bone test in a population suspected of having osteomyelitis of the foot in diabetes.

BACKGROUND We investigated the validity of probe-to-bone testing in the diagnosis of osteomyelitis in a selected subgroup of patients clinically suspected of having diabetic foot osteomyelitis. METHODS Between January 1, 2007, and December 31, 2008, inpatients and outpatients with a diabetic foot ulcer were prospectively evaluated, and those having a clinical diagnosis of foot infection and at least one of the osteomyelitis clinical suspicion criteria were consecutively included in this study. RESULTS Sixty-five patients met the inclusion criteria and were prospectively enrolled in the study. Forty-nine patients (75.4%) were hospitalized, and the remaining 16 (24.6%) were followed as outpatients. Osteomyelitis was diagnosed in 39 patients (60.0%). Probe-to-bone test results were positive in 30 patients (46.1%). The positive predictive value for the probe-to-bone test was fairly high (87%), but the negative predictive value was only 62%. The sensitivity and specificity of the test were 66% and 84%, respectively. White blood cell counts and mean C-reactive protein levels did not statistically significantly differ between groups. However, erythrocyte sedimentation rates greater than 70 mm/h reached statistical significance between groups. Wound area and depth were not found to be statistically significantly different between groups. CONCLUSIONS Positive probe-to-bone test results and erythrocyte sedimentation rates greater than 70 mm/h provide some support for the diagnosis of diabetic foot osteomyelitis, but it is not strong; magnetic resonance imaging or bone biopsy will probably be required in cases of doubt.

Hyperbaric Oxygen as Adjunctive Therapy in Experimental Mediastinitis

BACKGROUND Mediastinitis is a dreaded complication of cardiac surgical procedures. The purpose of our study was to research the role of hyperbaric oxygen therapy (HBO) in the treatment of experimental mediastinitis and to investigate whether it potentiates the antibiotic effects of linezolid, teicoplanin, and vancomycin. METHODS The study included nine groups; an uncontaminated and a contaminated untreated control groups, and seven contaminated groups that received HBO or systemic antibiotics with linezolid, vancomycin, or teicoplanin, or a combination therapy consisting of one of these antibiotics and HBO. There were six adult male Wistar rats in each group. Contaminated groups were inoculated with 0.5 mL 10(8) CFU/mL methicillin resistant Staphylococcus aureus in the mediastinal and in the sternal layers. The antibiotic treatment continued 7 d. Twelve hours later at the end of the treatment, the rats were sacrificed, a sternotomy was performed for each rat and tissue samples from the upper ends of the sternum were aseptically obtained and evaluated microbiologically. RESULTS There was no difference between the therapeutic efficacy of linezolid, teicoplanin, or vancomycin (P>0.05). When the groups were analyzed separately, treatment with a combination of HBO and antibiotic therapy reduced the bacterial count in comparison with HBO or antibiotic treatment alone (P<0.05). The combination of teicoplanin or vancomycin and HBO, respectively, was not more effective in reducing the bacterial count in comparison with the combination of linezolid and HBO (P>0.05). CONCLUSIONS Linezolid and teicoplanin therapy was found as effective as standard vancomycin therapy for methicillin resistant Staphylococcus aureus (MRSA) mediastinitis. Adjunctive HBO offered additional benefit to the antibiotic treatment of mediastinitis.

Hyperbaric Oxygen Therapy Attenuates Renal Ischemia/Reperfusion Injury in Rats

Objective: Renal ischemia/reperfusion (I/R) injury occurs in both native and transplanted kidneys. Hyperbaric oxygen (HBO) has been shown to prevent I/R injury in different tissues. The aim of this study was to evaluate the effect of HBO on renal I/R injury in rats. Materials and Methods: Sprague-Dawley rats were randomly assigned to one of three groups. The Control group (n = 6) received right nephrectomy. The I/R (n = 6) and I/R+HBO groups (n = 6) received 30 min left renal ischemia followed by 24 h of reperfusion after right nephrectomy. The I/R+HBO group (n = 6) received additional HBO therapy for 60 min at 2.5 absolute atmospheres starting at the initial 15th minute of reperfusion. Results: In the I/R group, blood urea nitrogen (BUN) and creatinine levels increased significantly compared with the Control and I/R+HBO groups (p < 0.05). BUN and creatinine levels were similar in the Control and I/R+HBO groups. Kidney samples from I/R group rats revealed severe tubular damage and neutrophil infiltration at histopathological examination. The animals treated with HBO showed markedly improved lesions and less neutrophil infiltration compared with the I/R group (p < 0.05). Conclusions: HBO exhibited marked protection against I/R injury in this study as measured using BUN and creatinine levels and renal histopathology. However, further studies are needed to clarify the renoprotective effect of HBO on I/R injury.

Can procalcitonin predict bone infection in people with diabetes with infected foot ulcers? A pilot study

AIMS The diagnosis of osteomyelitis is a key step of diabetic foot management. Previous studies showed that procalcitonin (PCT), a novel infection marker, is superior to conventional infection markers in the diagnosis of diabetic foot infection. This study aimed to investigate the serum levels of PCT and other conventional infection markers in diabetic persons with and without osteomyelitis. METHODS Twenty-four patients (18 male, mean age: 61.9±10.8 years) with infected foot ulcers were prospectively enrolled. Clinical characteristics of the wounds were noted. Blood samples were obtained for biochemical analysis. Magnetic resonance imaging of the foot was performed in all patients to diagnose osteomyelitis. RESULTS Osteomyelitis was found in 13 of 24 (54%) patients. PCT levels were 66.7±43.5 pg/ml in patients with osteomyelitis and 58.6±35.5 pg/ml in patients without osteomyelitis. The difference did not reach statistical significance (p=0.627). Erythrocyte sedimentation rate, but not C-reactive protein and white blood cell count, was found significantly higher in patients with osteomyelitis. CONCLUSION In this group of patients, PCT failed to discriminate patients with bone infection. Erythrocyte sedimentation rate can be used as a marker of osteomyelitis in diabetic persons.

Carbon Monoxide-Induced Cortical Visual Loss: Treatment with Hyperbaric Oxygen Four Years Later

Objective: We present a patient who developed visual loss after carbon monoxide (CO) poisoning and was treated with hyperbaric oxygen. Clinical Presentation and Intervention: A 21-year-old woman poisoned with CO (with coma lasting 4 h and carboxyhemoglobin level 46%) developed seizures and cortical blindness 3 days after poisoning. Four years later, her visual acuity was 0.2 in both eyes. An 18F-fluorodeoxyglucose positron emission tomography (PET) scan showed reduced metabolism in the bilateral posterior temporal and occipital lobes. The patient received a total of 50 hyperbaric oxygen sessions over 3 months for visual loss and the visual acuity improved to 0.5 in both eyes. In addition, increased metabolism was detected in the brain in post-treatment PET scans. Conclusion: PET documented brain hypoperfusion 4 years after CO poisoning and hyperbaric oxygen therapy improved visual acuity. However, we cannot endorse routine use of hyperbaric oxygen for such patients, until results of further clinical trials demonstrate efficacy of hyperbaric oxygen in CO-induced chronic brain injury.

The effect of hyperbaric oxygen therapy on the delay procedure.

Background: This study evaluates the possibility of enhancing the beneficial effect of the delay procedure by using hyperbaric oxygen therapy, and the possibility of lessening the time required for maximal effect of delay procedure. Methods: Eight male Wistar rats were used in each of 10 groups. The surgical delay method was applied to the caudally based dorsal rat flap by incising the longitudinal borders and undermining the flap. In the first five groups, 3-, 7-, 10-, 14-, and 21-day delay periods were applied, and in the other five groups, hyperbaric oxygen therapy was applied during the delay periods. Blood circulation was measured with a laser Doppler flowmeter, and flap survival lengths were recorded. Histological analysis for vascular counting and determining vascular areas and microangiographic analysis for monitoring vascular status were performed. Results: In addition to the flap viabilities being increased, the maximum effect of the delay procedure could be achieved earlier with hyperbaric oxygen therapy. Blood circulation in the flaps, vascular counts, and vascular areas were increased by applying hyperbaric oxygen during the delay period. Microangiographic results confirmed the beneficial effect of hyperbaric oxygen treatment. Conclusions: Hyperbaric oxygen treatment during the delay period can lessen the time period needed for the delay procedure and increase the effect of the delay itself.