Evaluation of a new hyperbaric oxygen ventilator during volume-controlled ventilation.

INTRODUCTION: The performance of the Shangrila590 hyperbaric ventilator (Beijing Aeonmed Company, Beijing, China) was evaluated during volume-controlled ventilation. METHODS: Experiments were conducted in a multiplace hyperbaric chamber at 101, 152, 203, and 284 kPa (1.0, 1.5, 2.0 and 2.8 atmospheres absolute [atm abs]). With the ventilator in volume control ventilation (VCV) mode and connected to a test lung, comparison was made of the set tidal volume (VTset) versus delivered tidal volume (VT) and minute volume (MV) at VTset between 400 and 1,000 mL. Peak inspiratory pressure was also recorded. All measurements were made across 20 respiratory cycles. RESULTS: Across all ambient pressures and ventilator settings the difference between VTset and actual VT and between predicted MV and actual MV were small and clinicially insignificant despite reaching statistical significance. Predictably, Ppeak increased at higher ambient pressures. With VTset 1,000 mL at 2.8 atm abs the ventilator produced significantly greater VT, MV and Ppeak. CONCLUSIONS: This new ventilator designed for use in hyperbaric environments performs well. It provides relatively stable VT and MV during VCV with VTset from 400 mL to 800 mL at ambient pressures from 1.0 to 2.8 atm abs, as well as VTset 1,000 mL at ambient pressures from 1.0 to 2.0 atm abs.

EEG microstate changes during hyperbaric oxygen therapy in patients with chronic disorders of consciousness.

Hyperbaric oxygen (HBO) therapy is an effective treatment for patients with disorders of consciousness (DOC). In this study, real-time electroencephalogram (EEG) recordings were obtained from patients with DOC during HBO therapy. EEG microstate indicators including mean microstate duration (MMD), ratio of total time covered (RTT), global explained variance (GEV), transition probability, mean occurrence, and mean global field power (GFP) were compared before and during HBO therapy. The results showed that the duration of microstate C in all patients with DOC increased after 20 min of HBO therapy (p < 0.05). Further statistical analysis found that the duration of microstate C was longer in the higher CRS-R group (≥8, 17 cases) than in the lower group (<8, 24 cases) during HBO treatment. In the higher CRS-R group, the transition probabilities from microstate A to microstate C and from microstate C to microstate A also increased significantly compared with the probability before treatment (p < 0.05). Microstate C is generally considered to be related to a salience network; an increase in the transition probability between microstate A and microstate C indicates increased information exchange between the auditory network and the salience network. The results of this study show that HBO therapy has a specific activating effect on attention and cognitive control in patients and causes increased activity in the primary sensory cortex (temporal lobe and occipital lobe). This study demonstrates that real-time EEG detection and analysis during HBO is a clinically feasible method for assessing brain function in patients with DOC. During HBO therapy, some EEG microstate indicators show significant changes related to the state of consciousness in patients with chronic DOC. This will be complementary to important electrophysiological indicators for assessing consciousness and may also provide an objective foundation for the precise treatment of patients with DOC.

A Novel Diagnostic Prediction Model for Vestibular Migraine.

BACKGROUND: Increasing morbidity and misdiagnosis of vestibular migraine (VM) gravely affect the treatment of the disease as well as the patients' quality of life. A powerful diagnostic prediction model is of great importance for management of the disease in the clinical setting. MATERIALS AND METHODS: Patients with a main complaint of dizziness were invited to join this prospective study. The diagnosis of VM was made according to the International Classification of Headache Disorders. Study variables were collected from a rigorous questionnaire survey, clinical evaluation, and laboratory tests for the development of a novel predictive diagnosis model for VM. RESULTS: A total of 235 patients were included in this study: 73 were diagnosed with VM and 162 were diagnosed with non-VM vertigo. Compared with non-VM vertigo patients, serum magnesium levels in VM patients were lower. Following the logistic regression analysis of risk factors, a predictive model was developed based on 6 variables: age, sex, autonomic symptoms, hypertension, cognitive impairment, and serum Mg2+ concentration. The area under the curve (AUC) of the receiver operating characteristic (ROC) curve was 0.856, which was better than some of the reported predictive models. CONCLUSION: With high sensitivity and specificity, the proposed logistic model has a very good predictive capability for the diagnosis of VM. It can be used as a screening tool as well as a complementary diagnostic tool for primary care providers and other clinicians who are non-experts of VM.

Effect of large dose hyperbaric oxygenation therapy on prognosis and oxidative stress of acute permanent cerebral ischemic stroke in rats.

OBJECTIVE: To evaluate the therapeutic effect and the oxidative stress effect of 9 and 18 hour hyperbaric oxygenation therapy (HBOT) protocols on the earliest stage of acute permanent middle cerebral artery occlusion (MCAO) in rats. METHODS: The permanent MCAO model of rats was used. The animals were randomly divided into 9 and 18 hour HBOT groups, as well as a control group. MAIN OUTCOME MEASURES: (1) The Garcia neurological grading system was used to assess the therapeutic effect of hyperbaric oxygenation therapy; (2) the infarct volume was calculated with the 2,3,5-triphenyltetrazolium chloride (TTC) pathologic staining and NIH Image J software 24 and 120 hours after MCAO; (3) the level of reactive oxygen species determined by superoxide dismutase (SOD), malondialdehyde (MDA) and nitric oxide (NO) in ischemic brain tissue were separately examined at the 18, 48 and 120 hour post-ischemia time points using spectrophotometry. RESULTS: (1) There were significant improvements in the neurobehavioral outcome of the rats in the 9 and the 18 hour groups, as compared with rats from the control group (p<0.01); (2) cerebral infarct volume decreased 63-64% in the rats of 9 hour group and 51-66% in the 18 hour group at the 24 and 120 hour time points, as compared with that of the control group; (3) the SOD levels of the 9 and 18 hour groups were remarkably lower than those of control group after both 18 and 48 hours (p<0.01 and p<0.05); (4) the MDA level of the 9 and 18 hour groups were both remarkably lower than the control groups, especially at 18 hours (p<0.05). Meanwhile, the MDA level in the 9 hour group was remarkably lower than both the 18 hour group and the control group (p<0.01 and p<0.05); (5) the level of NO in both hyperbaric oxygenation therapy groups were remarkably higher than that of the control at 18 and 48 hour time points (p<0.01). While the level in 18 hour group was remarkably lower than that of 9 hour group at 18 hour time point (p<0.05). At the 120 hour mark, the NO levels were basically the same in all the three groups. CONCLUSIONS: (1) The two protocols of large dose hyperbaric oxygenation therapy are highly efficient in reducing infarct volume and improving neurobehavioral outcome in permanent MCAO rats within the earliest stages of stroke; (2) increased duration of hyperbaric oxygenation therapy does not appear to equate to improved outcomes; in fact, the longer duration may aggravate the oxidative stress in ischemic tissue.