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.

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.

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.

Mechanistic Rationale and Clinical Efficacy of Hyperbaric Oxygen Therapy in Chronic Neuropathic Pain: An Evidence-Based Narrative Review.

Background: Chronic neuropathic pain is a condition affecting an increasing proportion of the general population and its management requires a comprehensive, multidisciplinary program. A growing body of evidence supports the use of hyperbaric oxygen therapy (HBOT) in several chronic neuropathic pain conditions; however, its role and efficacy remain unclear. Purpose: To summarize current evidence for the mechanistic rationale of HBOT in chronic neuropathic pain conditions and to evaluate its clinical efficacy. Methods: This narrative review was conducted after searching the following databases (Medline, Embase, Cochrane, PsycINFO, the Web of Science, Scopus, ClinicalTrials. gov, WHO ICTRP, and ProQuest Digital Dissertation) from January 1946 to March 2020. Articles published in English that involved either animal or human studies with acute or chronic neuropathic pain evaluating any HBOT-related intervention were included. Results: A total of 2971 citations were identified. A total of 29 studies were included in this review. The mechanisms of action for HBOT use in neuropathic conditions included the primary effects of hyperoxia and edema resolution, as well as the secondary effects pertinent to the production of oxygen and nitrogen reactive species (serving as pain signaling molecules), nitric oxide-dependent release of opioid peptides, and reduction of inflammatory mediators. A robust evidence for HBOT use in the clinical setting was associated with chronic regional pain syndrome and chronic primary bladder pain syndrome. Some evidence supported its use for chronic secondary (peripheral) neuropathic pain including radiation-induced plexus neuropathies, postherpetic neuralgia, and trigeminal neuralgia. Conclusions: HBOT has been shown to have antinociceptive and analgesic effects in animal models of inflammatory, neuropathic, and chronic pain. Human studies demonstrated beneficial effects of HBOT in improving clinical outcomes such as pain scores, pain-related symptoms, and quality of life. A systematic methodology of HBOT application is necessary to confirm its safety and efficacy.

Magnitude and Clinical Predictors of Blood Pressure Changes in Patients Undergoing Hyperbaric Oxygen Therapy: A Retrospective Study.

Hyperbaric oxygen therapy (HBOT) is widely used to treat several pathologies. The hemodynamic changes during HBOT, particularly the magnitude of arterial blood pressure (ABP) increase, are not completely understood. No clinical predictors for HBOT-induced ABP increase have been described. The purpose of this study was to quantify ABP changes in patients undergoing HBOT and to examine their predictors. This retrospective longitudinal cohort study examined 3291 elective HBOT sessions. Non-invasive ABP was recorded before and after each session. The primary outcome was to quantify the HBOT-induced ABP rise. The secondary outcome was to determine the ABP-rise predictors among demographic and clinical variables. Overall, ABP increased significantly after HBOT; this finding was more evident in the hypertensive subgroup compared to the normotensive one (+6 vs. +16.2 mmHg). Clinical predictors of significant post-HBOT ABP change were history of hypertension and pre-session baseline ABP classification. This study demonstrates an absolute HBOT-induced ABP rise. This change is clinically relevant in patients with history of hypertension. A higher baseline ABP seems a risk factor for clinically relevant ABP change. Pre-session ABP should be used clinically as an indicator for strict ABP monitoring during HBOT; future studies are recommended to explore the ABP optimization before starting an HBO treatment.

The Treatment of Perioperative Spinal Cord Injury With Hyperbaric Oxygen Therapy: A Case Report.

STUDY DESIGN: Case report (level IV evidence). OBJECTIVE: To describe a potential novel application of hyperbaric oxygen therapy (HBOT) in the successful treatment of a postoperative spinal cord injury. SUMMARY OF BACKGROUND DATA: A 68-year-old man presented with an acute spinal cord injury (ASIA impairment scale D), on the background of degenerative lower thoracic and lumbar canal stenosis. He underwent emergent decompression and instrumented fusion (T9-L5), with an uncomplicated intraoperative course and no electrophysiological changes. Immediate postoperative assessment demonstrated profound bilateral limb weakness (1/5 on the Medical Research Council [MRC] grading scale, ASIA impairment scale B), without radiological abnormality. METHODS: Conventional medical management (hypertension, level 2 care) was instigated with the addition of Riluzole, with no effect after 30 hours. At 36 hours 100% oxygen at 2.8 atmospheres was applied for 90 minutes, and repeated after 8 hours, with a further three treatments over 48 hours. RESULTS: The patient demonstrated near-immediate improvement in lower limb function to anti-gravity (MRC grading 3/5) after one treatment. Motor improvement continued over the following treatments, and after 2 weeks the patient was ambulatory. At 4 months, the patient demonstrated normal motor function with no sphincteric disturbance. CONCLUSION: The application of HBOT contributed to the immediate and sustained improvement (ASIA B to ASIA E) in motor recovery after postoperative spinal cord injury. HBOT may represent a new avenue of therapy for spinal cord injury, and requires further prospective investigation. LEVEL OF EVIDENCE: 4.