[On the opportunity of treating with hyperbaric oxygenation (hyperbaric oxygen) for the prevention of post-interventional anoxic encephalopathy (delayed neurologic sequelae)].
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Adult↗
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Treatment of acute intestinal ischemia with hyperbaric oxygen.
Hyperbaric oxygen has been shown to improve oxygen tension and promote wound healing. We did a pilot study in which we created ischemic jejunal segments measuring 3, 6, and 9 cm, 10 of each length, in 30 rats. Half of the rats were given hyperbaric oxygen at 100%, 30 psi, for 90 minutes twice daily for 7 days to determine whether hyperbaric oxygen therapy could overcome the ischemic intestinal injury and prevent ischemic necrosis. In the rats with 6- and 9-cm ischemic segments, no difference was seen between the hyperbaric oxygen and control groups. Of the rats with 3-cm ischemic segments, ischemic infarction of the bowel developed in 40% of the hyperbaric oxygen group and 100% of the controls (P = 0.167, Fisher's Exact Test). We then created 3-cm ischemic intestinal segments in 30 additional rats. Again, half were treated with hyperbaric oxygen as previously described for 7 days. There was no difference between the controls and the hyperbaric oxygen group in the rate of perforation (4 of 15 [27%] versus 1 of 15 [7%]) or stricture rate (8 of 15 [53%] versus 9 of 15 [60%]). We concluded that hyperbaric oxygen therapy is of limited value for the treatment of intestinal ischemias.
Acute Disease↗
The mechanisms by which hyperbaric oxygen and carbogen improve tumour oxygenation.
Hyperbaric oxygen (HBO) has been proposed to reduce tumour hypoxia by increasing the amount of dissolved oxygen in the plasma. That this actually occurs has not been verified experimentally. This study was performed to explore changes in tumour oxygenation induced by treatment with normobaric and hyperbaric oxygen and carbogen. R3230Ac mammary adenocarcinomas were implanted into Fisher 344 rats. Arterial blood gases, blood pressure and heart rate were monitored. Tumour oxygenation was measured polarographically in five sets of animals. They received either normobaric 100% oxygen, hyperbaric (3 atmospheres; atm) 100% oxygen, normobaric carbogen or hyperbaric (3 atm) carbogen (HBC) +/- bretylium. HBO reduced the mean level of low pO2 values (< 5 mmHg) from 0.49 to 0.07 (P = 0.0003) and increased the average median pO2 from 8 mmHg to 55 mmHg (P = 0.001). HBC reduced the level of low pO2 values from 0.82 to 0.51 (P = 0.002) an increased median pO2 from 2 mmHg to 6 mmHg (P = 0.05). Normobaric oxygen and carbogen did not change tumour oxygenation significantly. Sympathetic blockade with bretylium before HBC exposure improved oxygenation significantly more than HBC alone (low pO2 0.55-0.17, median pO2 4-17 mmHg). HBO and hyperbaric carbogen improved tumour oxygenation in this model, while normobaric oxygen or carbogen had no effect. Sympathetic-mediated vasoconstriction during hyperbaric carbogen caused it to be less effective than HBO. This mechanism also appeared to operate during normobaric carbogen breathing.
Adenocarcinoma↗
Experimental ischemic neuropathy: salvage with hyperbaric oxygenation.
Hyperbaric oxygenation is effective in augmenting the delivery of oxygen to tissue, but also causes oxidative stress. As part of our focus on improving peripheral nerve salvage from ischemic fiber degeneration, we evaluated whether hyperbaric oxygenation rescues peripheral nerve, rendered ischemic by microembolization, from ischemic fiber degeneration. The supplying arteries of rat sciatic nerve were embolized with microspheres of 14 microns diameter at moderate (2 x 10(6)) and high (5.6 x 10(6)) doses. Rats were randomized to receive hyperbaric oxygenation treatment (2.5 atm 100% oxygen for 2 hours/day for 7 days beginning within 30 minutes of ischemia), or room air. End points for the embolized limb were (1) behavioral scores (0-11 in increasing levels of limb function), (2) nerve action potential of sciatic-tibial nerve, (3) nerve blood flow, and (4) histological grade as percentage of fibers undergoing ischemic fiber degeneration (0 = < 5%; 1 = 5-25%; 2 = 26-50%; 3 = 51-75%; 4 = > 76%). Nerve blood flow and nerve action potential were uniformly absent and more than 90% of fibers had degenerated in both control and treatment groups receiving high doses. Control and treatment groups receiving moderate doses were well matched by level of ischemia (8.5 +/- 0.3 [N = 18] vs 7.7 +/- 0.4 ml/100 gm/min [N = 18], p > 0.05) but were significantly different by behavior score (5.6 +/- 0.7 vs 9.2 +/- 0.5 [N = 19], p < 0.001), nerve action potential (1.4 +/- 1.0 vs 3.9 +/- 0.5 [N = 6], p < 0.05), and histology (2.4 +/- 0.4 [N = 5] vs 0.8 +/- 0.5 [N = 4], p < 0.05). On single teased fiber evaluation, the predominant abnormality was E (axonal degeneration). We conclude that hyperbaric oxygenation will effectively rescue fibers from ischemic fiber degeneration, providing the ischemia is not extreme.
Action Potentials↗
Treatment of radiation-induced tissue injury by hyperbaric oxygen.
Hyperbaric oxygen therapy appears to be a beneficial adjunctive treatment modality in the management of radionecrosis of bone and soft tissue in the head and neck. The mechanism of such wound healing enhancement appears to be related to oxygen stimulation of fibroblastic activity and neovasculation. In this pilot study, involving 13 cases of refractory mandibular radionecrosis treated with hyperbaric oxygen, complete healing of soft tissue disease with covering of exposed bone has been noted in seven cases 11 to 27 months posttreatment; transient healing was seen in three cases; moderate to marked improvement in soft tissue disease has been noted in three cases. Pain relief was marked in six cases, moderate in four cases, and slight in one case of the 11 patients with significant pretreatment pain. Radiographic improvement was slight to moderate in ten cases. Four of the five patients with pathologic fractures developed a firm fibrous union of the mandibular segments during or shortly after treatment. Three additional cases of head and neck radionecrosis of other sites have noted significant improvement in their lesions during treatment. Three other patients with radionecrosis of the foot, hip, and vagina have also been treated with good results only in the vaginal case. None of the 19 patients treated with hyperbaric oxygen developed persistent or significant complications.
Female↗
[Accumulation of gaseous products of lipid peroxidation in the expired air of human subjects during hyperbaric oxygenation].
Hyperbaric oxygenation (1 atm. of pure oxygen, 60 min. exposure) resulted in a sharp increase of the endogenous lipoperoxidation level in humans which was evaluated by the pentane content in the exhaled air. That activation of endogenous lipid peroxidation was a short-term process: 2-3-fold increase of pentane content 10 min after exposure to hyperbaric oxygenation and levelling off to control values in 1 hour. It is recommended to use determination of endogenous lipid peroxidation by the pentane content in the exhaled air in order to find optimal regimens of hyperbaric oxygenation.
Adolescent↗
[Microcirculation in patients with systemic scleroderma during treatment using hyperbaric oxygenation].
Hyperbaric oxygenation treatment of systemic scleroderma has a favourable effect on microcirculatory changes whose positive dynamics can be demonstrated by conjunctival biomicroscopy. These changes include accelerated blood flow and decrease in the degree of erythrocyte aggregation. The method can be used for the objective assessment and for prognosis of the effectiveness of hyperbaric oxygenation treatment in patients with systemic scleroderma.
Adult↗
Effect of artificial airway on ear complications from hyperbaric oxygen.
Hyperbaric oxygen treatment is associated with an increased risk of barotrauma to the tympanic membrane and middle ear. An artificial airway may compromise normal eustachian tube function and equilibration of middle ear pressures. This retrospective study was designed to evaluate the risk of middle ear complications in 267 patients receiving hyperbaric oxygen (HBO) therapy and to compare those with and without artificial airways. Charts of all patients were reviewed for middle ear and tympanic membrane complications and myringotomy tube placement. Eighteen of the 267 patients had artificial airways. Seventeen (94%) of these 18 patients developed middle ear or tympanic membrane complications, and 11 (61%) required tympanostomy tubes for pain, hemotympanum, or serous otitis. In contrast, 114 (45.8%) of the 249 patients without airways developed ear complications, and 53 (21.3%) required tympanostomy tubes. These results suggest that patients with an artificial airway who are receiving HBO therapy are at greater risk for developing tympanic membrane and middle ear complications than nonintubated patients. Similarly, patients with artificial airways receiving HBO frequently require placement of tympanostomy tubes.
Barotrauma↗
Acutely administered melatonin reduces oxidative damage in lung and brain induced by hyperbaric oxygen.
Hyperbaric oxygen exposure rapidly induces lipid peroxidation and cellular damage in a variety of organs. In this study, we demonstrate that the exposure of rats to 4 atmospheres of 100% oxygen for 90 min is associated with increased levels of lipid peroxidation products [malonaldehyde (MDA) and 4-hydroxyalkenals (4-HDA)] and with changes in the activities of two antioxidative enzymes [glutathione peroxidase (GPX) and glutathione reductase (GR)], as well as in the glutathione status in the lungs and in the brain. Products of lipid peroxidation increased after hyperbaric hyperoxia, both GPX and GR activities were decreased, and levels of total glutathione (reduced+oxidized) and glutathione disulfide (oxidized glutathione) increased in both lung and brain areas (cerebral cortex, hippocampus, hypothalamus, striatum, and cerebellum) but not in liver. When animals were injected with melatonin (10 mg/kg) immediately before the 90-min hyperbaric oxygen exposure, all measurements of oxidative damage were prevented and were similar to those in untreated control animals. Melatonin's actions may be related to a variety of mechanisms, some of which remain to be identified, including its ability to directly scavenge free radicals and its induction of antioxidative enzymes via specific melatonin receptors.
Aldehydes↗
Other modalities of oxygen therapy: hyperbaric oxygen, nitric oxide, and ECMO.
Novel therapies for the next decade include hyperbaric oxygen, nitric oxide, and extracorporeal membrane oxygenation. Hyperbaric oxygen delivers oxygen at a pressure greater than one atmosphere and has been used in diseases ranging from decompression sickness to carbon monoxide poisoning. Inhaled nitric oxide, a potent vasodilator, has been used in the acute respiratory distress syndrome and for the diagnosis and treatment of pulmonary hypertension. Extracorporeal membrane oxygenation (ECMO) has been used to provide cardiopulmonary bypass support, particularly in the pediatric and neonatal population.
Administration, Inhalation↗
Recovery of the hypoxic ventilatory drive of rats from the toxic effect of hyperbaric oxygen.
Hyperbaric oxygen (HBO) exposure reduces the hypoxic ventilatory drive (HVD), probably by damaging the carotid bodies. The recovery of the HVD from HBO exposure was studied. The HVD was calculated from whole body plethysmographic recordings of the ventilatory response to greater than 85% and 2% O2 in N2 mixtures. Five groups of rats were exposed to HBO for 9 h at pressures of 1.9, 2.0, 2.1, 2.2, and 2.4 ATA, respectively. Each rat underwent three control measurements on different days prior to HBO exposures and then at various intervals following the exposure. Postexposure HVD was reduced to 28% of control values in the high PO2s. Ninety percent recovery of pre-exposure HVD was evident by 12-48 h although in some animals exposed to relatively low PO2s (1.9 and 2.0 ATA) HVD stabilized at a level lower than 100%. The recovery of the HVD in percent during the first 4 d following exposure can be expressed as an exponential function of the time from the termination of HBO: HVD = 28 + 72(1 - exp-0.053t) (t in hours). This information may be of importance in cases of repeated exposures to HBO where one tries to avoid cumulative damage to the carotid bodies, and in the care of the poorly oxygenated patient after HBO treatment.
Air Pressure↗
Assessment of visual contrast sensitivity in hyperbaric oxygen.
Hyperbaric oxygen therapy is used in ophthalmology in ischemic pathologies of the anterior and posterior segments. Our experiment was done on a healthy group of volunteers aged between 10 and 50 yr. We examined the subject's vision before and after acute HBO exposure (60 min at 2.5 atm abs with pure oxygen) to verify whether vasoconstriction induced by hyperoxemia can influence eyesight. We measured the psychophysical determination of the threshold contrast according to Maione-Maffei's zebra test. The results demonstrated that contrast sensitivity is significantly improved for almost all the studied frequencies in normal subjects after acute HBO exposure. We hypothesize that the visual system has a reserve which is activated by an improvement of retinal oxygenation.
Adolescent↗
[Reproducibility of somatosensory evoked potentials and EEG in normal humans under hyperbaric oxygenation].
Hyperbaric oxygenation (HBO) was reported to have a favorable influence on ischemic brain dysfunction, and also appeared to be useful in improving brain edema. Somatosensory evoked potentials (SEP) and EEG would be available as indicators of brain function. The purpose of this paper is to study reproducibility of the N1-amplitude of SEP and EEG under HBO. Materials were 10 normal volunteers, from 21 to 31 (mean age: 26) years old. Two stimulating needle electrodes were inserted into the skin at the wrist and somatosensory stimulations were applied to the median nerve with 1 msec duration square pulses. Stimulation pulses were generated regularly every 1 sec., and stimulus intensity was adjusted just above the thumb twitch threshold. Monopolar EEGs were recorded from 16 silver-cup electrodes on the scalp, and SEPs were recorded by averaging 250 responses in those EEGs using computer technique. N1-amplitude was determined by the vertical distance between peaks of the P1 and N1 components. EEGs were analyzed by Fast Fourier Transform and the square root of the averaged power of each frequency band (delta, theta, alpha 1, alpha 2, beta) was obtained and evaluated as the equivalent potential. EEGs under the influence of sleeping or artifacts, such as electromyograms, eye lid movements and wandering of the base line, were excluded in evaluating the EEGs. SEPs and EEGs recorded consecutively. The first record was taken before HBO under air breathing at 1ATA, the second during HBO under pure oxygen breathing at 2ATA, and the third after HBO under air breathing at 1ATA once again.(ABSTRACT TRUNCATED AT 250 WORDS)
Adult↗
[Indicators of the sympathetico-adrenal system in patients with peritonitis after hyperbaric oxygenation].
Hyperbaric oxygenation was used in 32 patients with acute peritonitis and terminal phases of the disease. Changes in the sympatho-adrenal system indices in the blood and excretion of catecholamines with urine during HBO course were investigated. The general pool of adrenaline and noradrenaline in the blood was shown to decrease, their excretion with urine to increase. Normalization of biosynthesis of precursors under the influence of HBO sessions was found.
Acute Disease↗
Osteoradionecrosis of the mandible. Treatment with hyperbaric oxygen.
Hyperbaric oxygen used in the treatment of 14 patients with intractable osteonecrosis of the mandible produced a favorable response in relief of pain, elimination of extraoral draining sinus tracts, the return of osseous union in areas of the abnormal fracture, and the rapid dissolution of sequestrum without suppuration, so that further loss of hard and soft tissue was minimized. This treatment is a more conservative approach in the management of osteoradionecrosis.
Adult↗
Management of chronic staphylococcal osteomyelitis of the temporal bone: the use of hyperbaric oxygen.
Hyperbaric oxygen (HBO) is an effective adjunct in the management of selected otolaryngologic problems including radiation-induced necrosis of the temporal bone, malignant external otitis, mandibular osteoradionecrosis and refractory osteomyelitis, soft tissue head and necrotizing fasciitis, compromised skin flaps and grafts, acute air or gas embolism, and otologic barotrauma. We describe the management of a patient with insidious Staphylococcus aureus osteomyelitis of the temporal bone by the use of HBO preoperatively and postoperatively in conjunction with surgical debridement. The possible application of angiogenic agents and tetracycline bone-labeling in combination with HBO therapy in the management of refractory neurotologic disease is discussed.
Chronic Disease↗
Genotoxicity of hyperbaric oxygen.
Hyperbaric oxygen (HBO) treatment is applied as a therapy for a wide variety of diseases with symptoms caused by lack of oxygen in the target tissues. However, it is known that exposure to high concentrations of oxygen may lead to oxidative stress and cause cell and tissue damage. Oxygen toxicity and possible cancer-promoting effects of HBO therapy have been a matter of serious concern. Although a cancer-inducing effect of HBO was not found to date, recent studies clearly indicated an induction of oxidative DNA damage in blood cells of healthy subjects after HBO under therapeutic conditions. The biological significance of this finding has been investigated in a series of in vitro and in vivo tests. This review summarizes these studies and critically discusses potential adverse genetic effects of HBO therapy. Furthermore, since an induction of anti-oxidative defense mechanisms has been determined after HBO exposure, a modified treatment regimen of HBO therapy is proposed which avoids genotoxic effects.
Animals↗
Experimental mandibular osteomyelitis: therapeutic trials with hyperbaric oxygen.
Hyperbaric oxygen (HBO) has been reported to be beneficial in the treatment of mandibular osteomyelitis; however, controlled laboratory studies have been limited to the long bones. In this study, osteomyelitis was created in surgically fractured rabbit mandibles by inoculation of Bacteroides melaninogenicus. Two months after inoculation, osteomyelitis was verified by bacterial cultures and inspection of the fracture sites. The animals were then randomly divided into treatment and control groups. The treatment group received HBO (2 atmospheres) for two hours daily for 40 treatment days, whereas the control group was maintained on ambient air. Although HBO therapy did not eliminate the chronic osteomyelitis, it did result in a significant improvement in sinus tract healing, osseous repair, and diminished mobility at the fracture site.
Animals↗