Safety of hyperbaric oxygen therapy in patients with heart failure: A retrospective cohort study.

BACKGROUND: Hyperbaric oxygen therapy (HBOT) has several hemodynamic effects including increases in afterload (due to vasoconstriction) and decreases in cardiac output. This, along with rare reports of pulmonary edema during emergency treatment, has led providers to consider HBOT relatively contraindicated in patients with reduced left ventricular ejection fraction (LVEF). However, there is limited evidence regarding the safety of elective HBOT in patients with heart failure (HF), and no existing reports of complications among patients with HF and preserved LVEF. We aimed to retrospectively review patients with preexisting diagnoses of HF who underwent elective HBOT, to analyze HBOT-related acute HF complications. METHODS: Research Ethics Board approvals were received to retrospectively review patient charts. Patients with a history of HF with either preserved ejection fraction (HFpEF), mid-range ejection fraction (HFmEF), or reduced ejection fraction (HFrEF) who underwent elective HBOT at two Hyperbaric Centers (Toronto General Hospital, Rouge Valley Hyperbaric Medical Centre) between June 2018 and December 2020 were reviewed. RESULTS: Twenty-three patients with a history of HF underwent HBOT, completing an average of 39 (range 6-62) consecutive sessions at 2.0 atmospheres absolute (ATA) (n = 11) or at 2.4 ATA (n = 12); only two patients received fewer than 10 sessions. Thirteen patients had HFpEF (mean LVEF 55 ± 7%), and seven patients had HFrEF (mean LVEF 35 ± 8%) as well as concomitantly decreased right ventricle function (n = 5), moderate/severe tricuspid regurgitation (n = 3), or pulmonary hypertension (n = 5). The remaining three patients had HFmEF (mean LVEF 44 ± 4%). All but one patient was receiving fluid balance therapy either with loop diuretics or dialysis. Twenty-one patients completed HBOT without complications. We observed symptoms consistent with HBOT-related HF exacerbation in two patients. One patient with HFrEF (LVEF 24%) developed dyspnea attributed to pulmonary edema after the fourth treatment, and later admitted to voluntarily holding his diuretics before the session. He was managed with increased oral diuretics as an outpatient, and ultimately completed a course of 33 HBOT sessions uneventfully. Another patient with HFpEF (LVEF 64%) developed dyspnea and desaturation after six sessions, requiring hospital admission. Acute coronary ischemia and pulmonary embolism were ruled out, and an elevated BNP and normal LVEF on echocardiogram confirmed a diagnosis of pulmonary edema in the context of HFpEF. Symptoms subsided after diuretic treatment and the patient was discharged home in stable condition, but elected not to resume HBOT. CONCLUSIONS: Patients with HF, including HFpEF, may develop HF symptoms during HBOT and warrant ongoing surveillance. However, these patients can receive HBOT safely after optimization of HF therapy and fluid restriction.

Successful treatment of neurologic injury after complex spinal surgery with hyperbaric oxygen therapy: a case report.

Background: Neurologic injury is relatively common in the context of spinal surgery, and is often treated with physiotherapy, pharmacotherapy, or surgical intervention. Emerging evidence supports a possible role for hyperbaric oxygen therapy (HBOT) in the treatment of peripheral and spinal nerve injuries. We describe the successful use of HBOT in improving neurologic recovery after complex spine surgery with new-onset postoperative unilateral foot drop. Case Description: A 50-year-old woman was found to have new right-sided foot drop and L2-S1 motor deficits following complex thoracolumbar revision spinal surgery. She received standard conservative management for a provisional diagnosis of acute traumatic nerve ischemia, but demonstrated no neurologic improvement. On postoperative day four, after other avenues of treatment were exhausted, she was referred for HBOT. The patient received a total of twelve sessions of HBOT at 2.0 absolute atmospheres (ATA) of pressure, for 90 minutes (including two air breaks) per session, before transfer to a rehabilitation facility. Conclusions: The patient displayed marked neurologic improvement after the first hyperbaric session, and further recovery thereafter. She concluded therapy with a significantly improved range of motion and lower limb power, ability to ambulate, and pain control. HBOT was associated with a rapid, sustained improvement when applied in this case as a salvage therapy for persistent postoperative neurologic deficit. Mounting evidence supports the consideration of hyperbaric therapy as a standard adjunct treatment for traumatic neurologic injury.

Pulmonary function following hyperbaric oxygen therapy: A longitudinal observational study.

Hyperbaric oxygen therapy (HBOT) is known to be associated with pulmonary oxygen toxicity. However, the effect of modern HBOT protocols on pulmonary function is not completely understood. The present study evaluates pulmonary function test changes in patients undergoing serial HBOT. We prospectively collected data on patients undergoing HBOT from 2016-2021 at a tertiary referral center (protocol registration NCT05088772). Patients underwent pulmonary function testing with a bedside spirometer/pneumotachometer prior to HBOT and after every 20 treatments. HBOT was performed using 100% oxygen at a pressure of 2.0-2.4 atmospheres absolute (203-243 kPa) for 90 minutes, five times per week. Patients' charts were retrospectively reviewed for demographics, comorbidities, medications, HBOT specifications, treatment complications, and spirometry performance. Primary outcomes were defined as change in percent predicted forced expiratory volume in one second (FEV1), forced vital capacity (FVC), and forced mid-expiratory flow (FEF25-75), after 20, 40, and 60 HBOT sessions. Data was analyzed with descriptive statistics and mixed-model linear regression. A total of 86 patients were enrolled with baseline testing, and the analysis included data for 81 patients after 20 treatments, 52 after 40 treatments, and 12 after 60 treatments. There were no significant differences in pulmonary function tests after 20, 40, or 60 HBOT sessions. Similarly, a subgroup analysis stratifying the cohort based on pre-existing respiratory disease, smoking history, and the applied treatment pressure did not identify any significant changes in pulmonary function tests during HBOT. There were no significant longitudinal changes in FEV1, FVC, or FEF25-75 after serial HBOT sessions in patients regardless of pre-existing respiratory disease. Our results suggest that the theoretical risk of pulmonary oxygen toxicity following HBOT is unsubstantiated with modern treatment protocols, and that pulmonary function is preserved even in patients with pre-existing asthma, chronic obstructive lung disease, and interstitial lung disease.

Clinical Considerations for Implanted Neurological Devices in Patients Undergoing Hyperbaric Oxygen Therapy: A Case Report and Review of Manufacturer Guidelines.

Patients with implanted medical devices are increasingly referred for hyperbaric oxygen therapy (HBOT), and the safety of exposing some of these devices to hyperbaric environments has not previously been explored. There is a paucity of evidence surrounding the management of implanted neurological devices such as neurostimulators and intrathecal drug delivery (IDD) pumps in the context of HBOT. However, these devices can be expected to harbor unique risks; for example, vacant space in the reservoir of an implanted IDD pump may change in pressure and volume during the compression and decompression phases of HBOT, resulting in a damaged or dysfunctional device. We present the case of a 27-year-old woman with cerebral palsy referred for HBOT to manage a necrotizing soft tissue infection cultured from a dehiscent abdominal wound at the previous implantation site of an intrathecal baclofen pump. An HBOT protocol was ultimately chosen in partnership with the patient and her family, but treatment was not performed due to a paucity of evidence that the implanted IDD pump could safely withstand hyperbaric exposure. In this review, we have synthesized manufacturer recommendations regarding the management of implanted neurological devices before, during, and after HBOT to inform future decision-making in this setting. Among these recommendations, we highlight that neurostimulators should be switched off for the duration of HBOT and implanted pumps should be refilled prior to each treatment session to minimize empty reservoir space.

Bygone theatres of events: A history of human anatomy and dissection.

Over the last four millennia, the discipline of anatomy and its relationships with medicine and society have evolved dramatically. Human dissection, the perennial tool for anatomical discovery and education, has both guided this evolution and matured alongside it. Soon after the first cadaveric dissections recorded in ancient Greece, China, India, and Persia, clear endorsements of its practice fell largely silent in the anatomical record for 1,500 years before reappearing in Europe at the dawn of the Renaissance. Between the 13th and 18th centuries CE, the performance of anatomical dissection became a popular form of education and public entertainment, and the demand for human cadavers steadily increased among European anatomical schools while supply remained limited by legal statute. This gave rise to an informal group of amateur and professional body snatchers called the Resurrectionists and, later, inspired the Anatomy Act of 1832 CE. In the 20th and 21st centuries CE, voluntary body bequeathal programs have enabled the practice of human dissection to continue in academic centers as a cornerstone of anatomical education, now with a newfound focus on the development of affective skills. This article provides an abridged account of anatomy's development, highlighting key moments in its growth, the valuable contributions of many different societies to the discipline, and the important roles of several luminary anatomists of antiquity. Within the broader context of this history, it offers an overview of anatomical dissection's evocative past, spanning from its inception to its present-day practice.