Non-invasive monitoring of carboxyhemoglobin during hyperbaric oxygen therapy.

Introduction: This study aimed to assess the capability of a pulse CO-oximeter to continuously monitor carboxyhemoglobin (COHb) during hyperbaric oxygen (HBO2) therapy. We estimated limits of agreement (LOA) between blood gas analysis and pulse CO-oximeter for COHb during HBO2 therapy in patients suffering from acute CO poisoning. Furthermore, we did a medicotechnical evaluation of the pulse CO-oximeter in hyperbaric conditions. Methods: We conducted a prospective, non-clinical, observational study in which we included n=10 patients with acute CO poisoning referred for HBO2 therapy. We did five repeated measurements of COHb for each patient during the HBO2 therapy. Bland-Altman analysis for multiple observations per individual was used to assess the agreement. The a priori LOA was ±6% for COHb. For the medicotechnical evaluation continuous measurements were obtained throughout each complete HBO2 therapy. The measurements were visually inspected and evaluated. Results: The Bland-Altman analysis showed that the pulse CO-oximeter overestimated COHb by 2.9 % [±1.0%] and the LOA was ±7.3% [±1.8%]. The continuous measurements by pulse CO-oximetry showed fluctuating levels of COHb and summarized saturations reached levels above 100%. Measurements were not affected by changes in pressure. Conclusion: To our knowledge, this study is the first to assess LOA and demonstrate use of a non-invasive method to measure COHb during HBO2 therapy. The pulse CO-oximeter performed within the manufactures reported LOA (±6%) despite hyperbaric conditions and was unaffected by changes in pressure. However, summarized saturations reached levels above 100%.

Quantitative Romberg's test in acute carbon monoxide poisoning treated by hyperbaric oxygen.

OBJECTIVE: The aim of this study was to evaluate whether monitoring of acute carbon monoxide-poisoned (COP) patients by means of quantitative Romberg's test (QR-test) during a hyperbaric oxygen (HBO2) therapy regimen could be a useful supplement in the evaluation of neurological status. METHODS: We conducted a retrospective study (2000-2014) in which we evaluated data containing quantitative sway measurements of acute COP patients (n = 58) treated in an HBO2 regimen. Each patient was tested using QR-test before and after each HBO2 treatment. Data were analyzed using linear mixed models (LMM). In each LMM, sway prior to HBO2 therapy was set as the fixed effect and change in sway after HBO2 therapy was set as the response variable. Patient, treatment number, weight and age were set as random effects for all LMMs. RESULTS: From the LMMs we found that larger values of sway prior to HBO2 produced a negative change in sway. We found no correlation between CO level and sway (P=0.1028; P=0.8764; P=0.4749; P=0.5883). Results showed that loss of visual input caused a significant increase in mean sway (P=0.028) and sway velocity (P⟨0.0001). CONCLUSIONS: The Quantitative Romberg's test is a fast, useful supplement to neurological evaluation and a potential valuable tool for monitoring postural stability during the course of treatment in acute COP patients.

Decompression illness treated in Denmark 1999-2013.

INTRODUCTION: The incidence, diver characteristics and symptomatology of decompression illness (DCI) in Denmark has not been assessed since 1982, and the presence of long-term residual symptoms among divers receiving hyperbaric oxygen therapy in Denmark has never been estimated to our knowledge. METHODS: We undertook a retrospective study of the incidence and characteristics of DCI cases in Denmark for the period of 1999 to 2013. Medical records and voluntary questionnaires were reviewed, extracting data on age, gender, weight, height, diver certification level, diving experience, number of previous dives, type of diving, initial type of hyperbaric treatment and DCI symptoms. Trend in annual case numbers was evaluated using run chart analysis and Spearman's correlation. Age, height, weight, and BMI were evaluated using linear regression. The presence of long-term residual symptoms was investigated by phone interviewing the subgroup of divers treated in 2009 and 2010. RESULTS: Two-hundred-and-five DCI cases were identified. The average annual case load was 14 with no significant trend during the study period (P = 0.081). Nor did we find any trend in age, weight, height or BMI. The most frequent symptoms were paraesthesia (50%), pain (42%) and vertigo (40%). Thirteen out of the subgroup of 30 divers had residual symptoms at discharge from hospital, and six out of 24 of these divers had residual symptoms at the time of follow-up. CONCLUSIONS: We observed a more than ten-fold increase in DCI-cases since the period 1966-1980. In the subgroup of divers treated in 2009/2010, a quarter had long-term residual symptoms as assessed by telephone interview, which is in keeping with the international literature, but still a reminder that DCI can have life-long consequences.

Survey of referral patterns and attitudes toward hyperbaric oxygen treatment among Danish oncologists, ear, nose and throat surgeons and oral and maxillofacial surgeons.

In head and neck cancer patients with late radiation injury, hyperbaric oxygen (HBO) is used for therapeutic or prophylactic reasons against soft-tissue and osteoradionecrosis (ORN). Twenty-nine departments of oncology, ENT, oral and maxillofacial (OMF) surgery were surveyed using the Enalyzer tool (www.enalyzer.com), of whom 21 responded. Data were incomplete in four returns. Within the previous year, 14 departments had referred at least one patient for hyperbaric oxygen therapy (HBOT). There appears to be a generally positive attitude in Danish OMF, ENT and oncology departments towards referral of patients with ORN for HBOT. However, there is an increasing desire for better evidence for its role in head and neck cancer in the prevention and treatment of soft-tissue injury and osteonecrosis following radiotherapy.

Cerebral proton magnetic resonance spectroscopy demonstrates reversibility of N-acetylaspartate/creatine in gray matter after delayed encephalopathy due to carbon monoxide intoxication: a case report.

INTRODUCTION: Predictive markers for long-term outcome in carbon monoxide-intoxicated patients with late encephalopathy are desired. Here we present the first data demonstrating a full reversibility pattern of specific brain substances measured by cerebral proton magnetic resonance spectroscopy in a carbon monoxide-intoxicated victim. This may provide clinicians with important information when estimating patient outcome. CASE PRESENTATION: We report the case of a 40-year-old Caucasian woman with severe carbon monoxide poisoning who was treated with five repetitive sessions of hyperbaric oxygen therapy in a multiplace chamber (100 percent oxygen with a ventilator, 90 minutes exposure to 2.8 atmospheres absolute). Initially, our patient recovered completely after three days of hospitalization, but became encephalopathic after a lucid interval of four weeks. An examination of the brain with cerebral proton magnetic resonance spectroscopy showed a dramatically decrease in N-acetylaspartate to total creatine ratios and elevated lactate levels in the gray matter. Subsequently, our patient received six additional sessions of hyperbaric oxygen therapy with only minimal recovery. At six-month follow-up our patient showed significant improvement in cognition and neuromuscular coordination. Extraordinarily, the cerebral proton magnetic resonance spectroscopy measurements at relapse compared to measurements at follow-up (217 days post insult) revealed full reversal of the severe abnormalities in mid-occipital gray matter and partial reversal in white matter. CONCLUSIONS: The present case indicates that cerebral proton magnetic spectroscopy provides valuable information on brain metabolism in patients presenting with delayed encephalopathy after acute carbon monoxide intoxication. The full reversal of N-acetylaspartate to total creatine ratios in gray matter has, to our knowledge, never been described before and shows that severe, initial measurements may not predict poor long-term patient outcome.

Monitoring cardiac output during hyperbaric oxygen treatment of haemodynamically unstable patients.

INTRODUCTION: Patients suffering from necrotizing fasciitis (NF) are often haemodynamically unstable and require extended monitoring of cardiovascular parameters; yet this is limited during hyperbaric oxygen treatment (HBOT). We aimed to evaluate the use and safety of transoesophageal Doppler (TED) monitoring of cardiac output (CO) under hyperbaric conditions in haemodynamically unstable patients diagnosed with NF and sepsis or septic shock. METHODS: Cardiac output was measured prior to, during and after HBOT with the use of TED in seven consecutive patients diagnosed with NF and sepsis or septic shock. The HBOT followed our standard protocol for NF patients, consisting of 90 minutes' exposure to 100% oxygen at 284 kPa. The difference between mean CO just prior to HBOT initiation and at near-maximum treatment duration was assessed using the Student's paired t-test. RESULTS: TED was feasible and easy to use under hyperbaric conditions. We experienced no problems with the measurement of CO or with equipment-related safety during HBOT. Five patients had an increase in CO from initiation of HBOT to near-maximum treatment duration, one patient had a stable CO, while one patient experienced a slight decrease in CO. Overall, there was an increase in mean CO of 1.7 L min-1 (95% CI 0.02 to 3.34 L min-1, P = 0.048) from initiation of HBOT to near-maximum treatment duration. CONCLUSION: This is, to the best of our knowledge, the first study to document that TED can provide a minimally-invasive estimate of CO in haemodynamically unstable patients with NF and sepsis or septic shock during HBOT.