Pre-Labor exposure to carbon monoxide: should the neonate be treated with hyperbaric oxygenation?

A woman was admitted to hospital in the 39th week of gestation due to syncope, followed by nausea and headache. The patient's history revealed a 10-hour, unintentional exposure to carbon monoxide (CO), secondary to burning charcoal for indoor heating. Because of monitored fetal distress, a cesarean section was performed. The newborn had an Apgar score of 4, 9, and 10 at 1, 5, and 10 minutes post-delivery, respectively. The 1-minute Apgar was low due to lack of spontaneous breathing, reduced tonus, bluish coloration, and reduced response to pain. The neonate's carboxyhemoglobin level seven hours post-CO exposure was 22%, and arterial pH was 7.28. Neurological examination 30 minutes after delivery showed no pathology. The neonate was treated with 100% normobaric oxygen for 12 hours. We discuss the treatment options for fetal CO poisoning and specific considerations that had to be taken into account in the present case.

Hyperbaric oxygen in the treatment of sudden deafness.

Currently, the treatment of sudden deafness (SD) is based mainly on complete bed rest and the administration of corticosteroids. Hyperbaric oxygen therapy (HBOT) has previously been suggested as adjunctive treatment. We describe two cases of successful HBOT for SD. The first patient presented with moderate mid-frequency hearing loss without accompanying symptoms, whereas the second patient had moderate low-frequency hearing loss with persistent tinnitus and a single episode of vertigo. HBOT in addition to conventional treatment soon after diagnosis resulted in full recovery of hearing in both patients. The pathogenesis of SD may involve a reduction in cochlear blood flow and perilymph oxygenation, making early HBOT a reasonable treatment modality for this condition.

Hyperbaric therapy for bilateral visual loss during hemodialysis.

Bilateral vision loss during hemodialysis is a rare but devastating entity, with grim prognosis for sight. The etiologies are diverse but share ischemia as a common mechanism. This is a report of a patient with bilateral sight loss during hemodialysis, with early hyperbaric treatment and return of visual acuity to baseline. Hyperbaric treatment should be considered, where early administration is possible, for bilateral blindness during hemodialysis.

Inner ear decompression sickness and mal de debarquement.

OBJECTIVE: To present a case series of vestibular symptoms appearing after combined sailing and diving activity, and to discuss the differential diagnosis and the workup algorithm. STUDY DESIGN: Case series. SETTING: Tertiary referral center. PATIENTS: Three patients aged 25 to 31 years suffering from unsteadiness and movement sensations after sailing and scuba diving. INTERVENTIONS: Neurotologic evaluation and recompression therapy in a hyperbaric chamber. MAIN OUTCOME MEASURES: The increasing popularity of marine sports and leisure activities has resulted in the exposure of a growing number of people to unique abnormalities not encountered under terrestrial conditions. The otolaryngologist who is involved in the care of these patients is required to diagnose and treat diving-related sinus and ear injuries such as barotrauma and decompression sickness, and also to be familiar with sailing-related disorientation syndromes such as seasickness and mal de debarquement. Treatment modalities for the various abnormalities differ significantly, and early commencement of treatment is often crucial for a successful outcome. CONCLUSION: Whenever doubt exists, recompression treatment must be instituted as soon as possible because of the potential for severe sequelae if the patient is left untreated, and because the risks involved in this therapy are minimal.

Attenuation of cerebral oxygen toxicity by sound conditioning.

HYPOTHESIS: Sound conditioning might reduce cerebral oxygen toxicity. BACKGROUND: Cerebral oxygen toxicity is related to high levels of reactive oxygen species. Noise-induced hearing loss has been shown to result from ischemia-reperfusion, in which reactive oxygen species play a major role. Repeated exposure to loud noise at levels below that which produces permanent threshold shift prevented noise-induced hearing loss and was associated with significant elevation of the antioxidant enzymes measured in the inner ear. We tested the hypothesis that sound conditioning might reduce cerebral oxygen toxicity. METHODS: Forty-five guinea pigs were prepared for electroencephalography and auditory brainstem recording. The auditory brainstem recording detection threshold was determined to confirm baseline normal hearing. The animals were divided into three equal groups and subjected to the following procedures: Group 1, electroencephalography electrode implantation and auditory brainstem recording only; Group 2, exposure to oxygen at 608 kPa (the latency to the first electrical discharge in the electroencephalogram preceding the appearance of seizures was measured); and Group 3, sound conditioning followed by oxygen exposure. The animals were killed, and the brains were excised and homogenized. Brain levels of superoxide dismutase, catalase, glutathione peroxidase, glutathione transferase, glutathione reductase, glucose-6-phosphate dehydrogenase, and thiobarbituric acid reactive substances were compared among the groups. RESULTS: Latency to the first electrical discharge was compared between Groups 2 and 3, and was found to be significantly longer in Group 3 (27.9 +/- 11 versus 20.4 +/- 7.6 min, p < 0.03). No significant changes were found in brain levels of superoxide dismutase, catalase, glutathione peroxidase, glutathione transferase, glutathione reductase, glucose-6-phosphate dehydrogenase, or thiobarbituric acid reactive substances. CONCLUSION: Our data show that sound conditioning prolongs the latency to oxygen-induced convulsions. This effect was not accompanied by significant changes in whole-brain antioxidant enzyme activity or the magnitude of lipid peroxidation.

Cardiogenic shock complicating acute carbon monoxide poisoning despite neurologic and metabolic recovery.

We report the cases of 2 previously healthy young patients with acute carbon monoxide intoxication who deteriorated to cardiogenic shock in the face of apparent metabolic and neurologic recovery. Prolonged exposure to sublethal levels of carbon monoxide (>24 hours, carboxyhemoglobin level of 20.4% and 22.6%) and massive binding of the toxin to myocardial myoglobin and mitochondrial cytochrome chain enzymes might explain their protracted cardiac failure. The good response to inotropic agents and the findings of repeated echocardiographic studies support the probable diagnosis of myocardial stunning. Complete cardiac recovery was observed in both patients.

Performance of infusion pumps during hyperbaric conditions.

BACKGROUND: Many hyperbaric facilities use infusion pumps inside the chamber. It is therefore important to ensure that this equipment will perform accurately during hyperbaric conditions. The authors tested the function and accuracy of the Imed 965 and Infutec 520 volumetric infusion pumps, the Easy-pump MZ-257 peristaltic infusion pump, and the Graseby 3100 syringe pump. METHODS: The authors calculated the deviations of infused volumes at low and high rates (12-18 and 60-100 ml/h) on three different hyperbaric protocols (up to 2.5, 2.8, and 6 atmospheres absolute [ATA]), resembling a standard hyperbaric oxygen treatment and US Navy treatment tables used for decompression illness and for arterial gas embolism. Two examples of each pump model were examined in every experiment. RESULTS: The Easy-pump MZ-257 failed to function completely beyond a chamber pressure of 1.4 ATA, making it unsuitable for use inside the hyperbaric chamber. The Graseby 3100 failed to respond to all keyboard functions at 2.5-2.8 ATA, making it unsuitable for use in most hyperbaric treatments. The Imed 965 performed within an acceptable volume deviation (< or =10%) during most hyperbaric conditions. During the compression phase of the profiles used, and for the low infusion rates only, exceptional volume deviations of 20-40% were monitored. The Infutec 520 demonstrated an acceptable deviation (within 10%) throughout all the hyperbaric profiles used, unaffected by changes in ambient pressure or infusion rate. CONCLUSIONS: Commercially available infusion pumps operating during hyperbaric conditions demonstrate substantial variations in performance and accuracy. It is therefore important that the hyperbaric facility staff make a careful examination of such instruments to anticipate possible deviations in the accuracy of the equipment during use.