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.

A Prospective Cohort Study of Acute Pain and In-Hospital Opioid Consumption After Cardiac Surgery: Associations With Psychological and Medical Factors and Chronic Postsurgical Pain.

BACKGROUND: Understanding the association of acute pain intensity and opioid consumption after cardiac surgery with chronic postsurgical pain (CPSP) can facilitate implementation of personalized prevention measures to improve outcomes. The objectives were to (1) examine acute pain intensity and daily mg morphine equivalent dose (MME/day) trajectories after cardiac surgery, (2) identify factors associated with pain intensity and opioid consumption trajectories, and (3) assess whether pain intensity and opioid consumption trajectories are risk factors for CPSP. METHODS: Prospective observational cohort study design conducted between August 2012 and June 2020 with 1-year follow-up. A total of 1115 adults undergoing cardiac surgery were recruited from the preoperative clinic. Of the 959 participants included in the analyses, 573 completed the 1-year follow-up. Main outcomes were pain intensity scores and MME/day consumption over the first 6 postoperative days (PODs) analyzed using latent growth mixture modeling (GMM). Secondary outcome was 12-month CPSP status. RESULTS: Participants were mostly male (76%), with a mean age of 61 ± 13 years. Three distinct linear acute postoperative pain intensity trajectories were identified: "initially moderate pain intensity remaining moderate" (n = 62), "initially mild pain intensity remaining mild" (n = 221), and "initially moderate pain intensity decreasing to mild" (n = 251). Age, sex, emotional distress in response to bodily sensations, and sensitivity to pain traumatization were significantly associated with pain intensity trajectories. Three distinct opioid consumption trajectories were identified on the log MME/day: "initially high level of MME/day gradually decreasing" (n = 89), "initially low level of MME/day remaining low" (n = 108), and "initially moderate level of MME/day decreasing to low" (n = 329). Age and emotional distress in response to bodily sensations were associated with trajectory membership. Individuals in the "initially mild pain intensity remaining mild" trajectory were less likely than those in the "initially moderate pain intensity remaining moderate" trajectory to report CPSP (odds ratio [95% confidence interval, CI], 0.23 [0.06-0.88]). No significant associations were observed between opioid consumption trajectory membership and CPSP status (odds ratio [95% CI], 0.84 [0.28-2.54] and 0.95 [0.22-4.13]). CONCLUSIONS: Those with moderate pain intensity right after surgery are more likely to develop CPSP suggesting that those patients should be flagged early on in their postoperative recovery to attempt to alter their trajectory and prevent CPSP. Emotional distress in response to bodily sensations is the only consistent modifiable factor associated with both pain and opioid trajectories.

Adjunctive hyperbaric oxygen therapy for spinal cord ischemia after complex aortic repair.

OBJECTIVE: Spinal cord ischemia (SCI) with paraplegia or paraparesis is a devastating complication of complex aortic repair (CAR). Treatment includes cerebrospinal fluid drainage, maintenance of hemoglobin concentration (>10 g/L), and elevating mean arterial blood pressure. Animal and human case series have reported improvements in SCI outcomes with hyperbaric oxygen therapy (HBOT). We reviewed our center's experience with HBOT as a rescue treatment for spinal cord ischemia post-CAR in addition to standard treatment. METHODS: A retrospective review of the University Health Network's Hyperbaric Medicine Unit treatment database identified HBOT sessions for patients with SCI post-CAR between January 2013 and June 2021. Mean estimates of overall motor function scores were determined for postoperative, pre-HBOT, post-HBOT (within 4 hours of the final HBOT session), and at the final assessment (last available in-hospital evaluation) using a linear mixed model. A subgroup analysis compared the mean estimates of overall motor function scores between improvement and non-improvement groups at given timepoints. Improvement of motor function was defined as either a ≥2 point increase in overall muscle function score in patients with paraparesis or an upward change in motor deficit categorization (para/monoplegia, paraparesis, and no deficit). Subgroup analysis was performed by stratifying by improvement or non-improvement of motor function from pre-HBOT to final evaluation. RESULTS: Thirty patients were treated for SCI. Pre-HBOT, the motor deficit categorization was 10 paraplegia, three monoplegia, 16 paraparesis, and one unable to assess. At the final assessment, 14 patients demonstrated variable degrees of motor function improvement; eight patients demonstrated full motor function recovery. Seven of the 10 patients with paraplegia remained paraplegic despite HBOT. The estimated mean of overall muscle function score for pre-HBOT was 16.6 ± 2.9 (95% confidence interval [CI], 10.9-22.3) and for final assessment was 23.4 ± 2.9 (95% CI, 17.7-29.1). The estimated mean difference between pre-HBOT and final assessment overall muscle function score was 6.7 ± 3.1 (95% CI, 0.6-16.1). The estimated mean difference of the overall muscle function score between pre-HBOT and final assessment for the improved group was 16.6 ± 3.5 (95% CI, 7.5-25.7) vs -4.9 ± 4.2 (95% CI, -16.0 to 6.2) for the non-improved group. CONCLUSIONS: HBOT, in addition to standard treatment, may potentially improve recovery in spinal cord function following SCI post-CAR. However, the potential benefits of HBOT are not equally distributed among subgroups.

Hyperbaric oxygen therapy for treatment of COVID-19-related parosmia: a case report.

Parosmia is a qualitative olfactory dysfunction characterized by distortion of odor perception. Traditional treatments for parosmia include olfactory training and steroids. Some patients infected with COVID-19 have developed chronic parosmia as a result of their infection. Here, we present the case of a patient who developed parosmia after a COVID-19 infection that was not improved by traditional treatments but found significant improvement after hyperbaric oxygen therapy[A1].

Impact of a Transitional Pain Service on postoperative opioid trajectories: a retrospective cohort study.

INTRODUCTION: It has been well described that a small but significant proportion of patients continue to use opioids months after surgical discharge. We sought to evaluate postdischarge opioid use of patients who were seen by a Transitional Pain Service compared with controls. METHODS: We conducted a retrospective cohort study using administrative data of individuals who underwent surgery in Ontario, Canada from 2014 to 2018. Matched cohort pairs were created by matching Transitional Pain Service patients to patients of other academic hospitals in Ontario who were not enrolled in a Transitional Pain Service. Segmented regression was performed to assess changes in monthly mean daily opioid dosage. RESULTS: A total of 209 Transitional Pain Service patients were matched to 209 patients who underwent surgery at other academic centers. Over the 12 months after surgery, the mean daily dose decreased by an estimated 3.53 morphine milligram equivalents (95% CI 2.67 to 4.39, p<0.001) per month for the Transitional Pain Service group, compared with a decline of only 1.05 morphine milligram equivalents (95% CI 0.43 to 1.66, p<0.001) for the controls. The difference-in-difference change in opioid use for the Transitional Pain Service group versus the control group was -2.48 morphine milligram equivalents per month (95% CI -3.54 to -1.43, p=0.003). DISCUSSION: Patients enrolled in the Transitional Pain Service were able to achieve opioid dose reduction faster than in the control cohorts. The difficulty in finding an appropriate control group for this retrospective study highlights the need for future randomized controlled trials to determine efficacy.

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.

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.

Prevention and Management of Chronic Postsurgical Pain and Persistent Opioid Use Following Solid Organ Transplantation: Experiences From the Toronto General Hospital Transitional Pain Service.

BACKGROUND: With >700 transplant surgeries performed each year, Toronto General Hospital (TGH) is currently one of the largest adult transplant centers in North America. There is a lack of literature regarding both the identification and management of chronic postsurgical pain (CPSP) after organ transplantation. Since 2014, the TGH Transitional Pain Service (TPS) has helped manage patients who developed CPSP after solid organ transplantation (SOT), including heart, lung, liver, and renal transplants. METHODS: In this retrospective cohort study, we describe the association between opioid consumption, psychological characteristics of pain, and demographic characteristics of 140 SOT patients who participated in the multidisciplinary treatment at the TGH TPS, incorporating psychology and physiotherapy as key parts of our multimodal pain management regimen. RESULTS: Treatment by the multidisciplinary TPS team was associated with significant improvement in pain severity and a reduction in opioid consumption. CONCLUSIONS: Given the risk of CPSP after SOT, robust follow-up and management by a multidisciplinary team should be considered to prevent CPSP, help guide opioid weaning, and provide psychological support to these patients to improve their recovery trajectory and quality of life postoperatively.

The role of hyperbaric oxygen therapy in the management of perioperative peripheral nerve injury: a scoping review of the literature.

BACKGROUND/IMPORTANCE: Peripheral nerve injury is an uncommon but potentially catastrophic complication of anesthesia and surgery, for which there are limited effective treatment options. Hyperbaric oxygen therapy is a unique medical intervention which improves tissue oxygen delivery and reduces ischemia via exposure to oxygen at supra-atmospheric partial pressures. While the application of hyperbaric oxygen therapy has been evidenced for other medical conditions involving relative tissue ischemia, its role in the management of peripheral nerve injury remains unclear. OBJECTIVE: This scoping review seeks to characterize rehabilitative outcomes when hyperbaric oxygen therapy is applied as an adjunct therapy in the treatment of perioperative peripheral nerve injury. EVIDENCE REVIEW: The review was conducted according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines for scoping reviews, using a systematic screening and extraction process. The search included articles published from database inception until June 11, 2022, which reported clinical outcomes (in both human and non-human models) of peripheral nerve injury treated with hyperbaric oxygen therapy. FINDINGS: A total of 51 studies were included in the narrative synthesis. These consisted of animal (40) and human studies (11) treating peripheral nerve injury due to various physiological insults. Hyperbaric oxygen therapy protocols were highly heterogenous and applied at both early and late intervals relative to the time of peripheral nerve injury. Overall, hyperbaric oxygen therapy was reported as beneficial in 88% (45/51) of included studies (82% of human studies and 90% of animal studies), improving nerve regeneration and/or time to recovery with no reported major adverse events. CONCLUSIONS: Existing data suggest that hyperbaric oxygen therapy is a promising intervention in the management of perioperative peripheral nerve injury, in which tissue ischemia is the most common underlying mechanism of injury, neurological deficits are severe, and treatment options are sparse. This positive signal should be further investigated in prospective randomized clinical trials.

The role of routine pulmonary imaging before hyperbaric oxygen treatment.

Respiratory injury during or following hyperbaric oxygen treatment (HBOT) is rare, but associated pressure changes can cause iatrogenic pulmonary barotrauma with potentially severe sequelae such as pneumothoraces. Pulmonary blebs, bullae, and other emphysematous airspace abnormalities increase the risk of respiratory complications and are prevalent in otherwise healthy adults. HBOT providers may elect to use chest X-ray routinely as a pre-treatment screening tool to identify these anomalies, particularly if a history of preceding pulmonary disease is identified, but this approach has a low sensitivity and frequently provides false negative results. Computed tomography scans offer greater sensitivity for airspace lesions, but given the high prevalence of incidental and insignificant pulmonary findings among healthy individuals, would lead to a high false positive rate because most lesions are unlikely to pose a hazard during HBOT. Post-mortem and imaging studies of airspace lesion prevalence show that a significant proportion of patients who undergo HBOT likely have pulmonary abnormalities such as blebs and bullae. Nevertheless, pulmonary barotrauma is rare, and occurs mainly in those with known underlying lung pathology. Consequently, routinely using chest X-ray or computed tomography scans as screening tools prior to HBOT for low-risk patients without a pertinent medical history or lack of clinical symptoms of cardiorespiratory disease is of low value. This review outlines published cases of patients experiencing pulmonary barotrauma while undergoing pressurised treatment/testing in a hyperbaric chamber and analyses the relationship between barotrauma and pulmonary findings on imaging prior to or following exposure. A checklist and clinical decision-making tool based on suggested low-risk and high-risk features are offered to guide the use of targeted baseline thoracic imaging prior to HBOT.

Efficacy and safety of hyperbaric oxygen treatment to treat COVID-19 pneumonia: a living systematic review update.

INTRODUCTION: As the COVID-19 pandemic evolves, new effective treatment options are essential for reducing morbidity and mortality as well as the strain placed on the healthcare system. Since publication of our initial review on hyperbaric oxygen treatment (HBOT) for hypoxaemic COVID-19 patients, interest in HBOT for COVID-19 has grown and additional studies have been published. METHODS: For this living systematic review update the previously published search strategy (excluding Google Scholar) was adopted with an extension from 01 February 2021 to 01 April 2022. Study inclusion criteria, data extraction, risk of bias estimation and dispute resolution methods were repeated. RESULTS: Two new studies enrolling 127 patients were included in this update, taking the total to eight studies with 224 patients. Both new studies were randomised controlled trials, one at moderate and one at high risk of bias. Across these eight studies, 114 patients were treated with HBOT. All reported improved clinical outcomes without observation of any serious adverse events. Meta-analysis remained unjustified given the high heterogeneity between studies and incomplete reporting. CONCLUSIONS: This updated living systematic review provides further evidence on the safety and effectiveness of HBOT to treat acute hypoxaemic COVID-19 patients.

Presurgical distress about bodily sensations predicts chronic postsurgical pain intensity and disability 6 months after cardiothoracic surgery.

ABSTRACT: Chronic postsurgical pain (CPSP) and disability after cardiothoracic surgery are highly prevalent and difficult to treat. Researchers have explored a variety of presurgical risk factors for CPSP and disability after cardiothoracic surgery, including one study that examined distress from bodily sensations. The current prospective, longitudinal study sought to extend previous research by investigating presurgical distress about bodily sensations as a risk factor for CPSP and disability after cardiothoracic surgery while controlling for several other potential psychosocial predictors. Participants included 543 adults undergoing nonemergency cardiac or thoracic surgery who were followed over 6 months postsurgically. Before surgery, participants completed demographic, clinical, and psychological questionnaires. Six months after surgery, participants reported the intensity of CPSP on a 0 to 10 numeric rating scale and pain disability, measured by the Pain Disability Index. Multinomial logistic regression analyses were conducted to evaluate the degree to which presurgical measures predicted pain outcomes 6 months after surgery. The results showed that CPSP intensity was significantly predicted by age and presurgical scores on the Symptom Checklist-90-Revised Somatization subscale (Nagelkerke R2 = 0.27, P < 0.001), whereas chronic pain disability was only predicted by presurgical Symptom Checklist-90-Revised Somatization scores (Nagelkerke R2 = 0.29, P < 0.001). These findings demonstrate that presurgical distress over bodily sensations predicts greater chronic pain intensity and disability 6 months after cardiothoracic surgery and suggest that presurgical treatment to diminish such distress may prevent or minimize CPSP intensity and disability.

Efficacy and safety of hyperbaric oxygen treatment in SARS-COV-2 (COVID-19) pneumonia: a systematic review.

INTRODUCTION: The need for intubation and mechanical ventilation among COVID-19 patients is associated with high mortality rates and places a substantial burden on the healthcare system. There is a strong pathophysiological rationale suggesting that hyperbaric oxygen treatment (HBOT), a low-risk and non-invasive treatment, may be beneficial for COVID-19 patients. This systematic review aimed to explore the potential effectiveness and safety of HBOT for treating patients with COVID-19. METHODS: Medline, Embase, Scopus, and Google Scholar were searched from December 2019 to February 2021, without language restrictions. The grey literature was searched via an internet search engine and targeted website and database searches. Reference lists of included studies were searched. Independent reviewers assessed studies for eligibility and extracted data, with disagreements resolved by consensus or a third reviewer. Risk of bias was assessed using the Newcastle Ottawa Scale. Data were summarised descriptively. RESULTS: Six publications (one cohort study, five case reports/series) met the inclusion criteria with a total of 37 hypoxaemic COVID-19 patients treated with HBOT. Of these 37 patients, the need for intubation and mechanical ventilation and in-hospital survival were assessed for 26 patients across three studies. Of these 26 patients, intubation and mechanical ventilation were not required for 24, and 23 patients survived. No serious adverse events of HBOT in COVID-19 patients were reported. No randomised trials have been published. CONCLUSIONS: Limited and weak evidence from non-randomised studies including one propensity-matched cohort study suggests HBOT is safe and may be a promising intervention to optimise treatment and outcomes in hypoxaemic COVID-19 patients. Randomised controlled studies are urgently needed.

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.

Predictors of one year chronic post-surgical pain trajectories following thoracic surgery.

PURPOSE: Chronic post-surgical pain (CPSP) is a highly prevalent complication following thoracic surgery. This is a prospective cohort study that aims to describe the pain trajectories of patients undergoing thoracic surgery beginning preoperatively and up to 1 year after surgery METHODS: Two hundred and seventy nine patients undergoing elective thoracic surgery were enrolled. Participants filled out a preoperative questionnaire containing questions about their sociodemographic information, comorbidities as well as several psychological and pain-related statuses. They were then followed-up during their immediate postoperative period and at the three, six and 12 month time-points to track their postoperative pain, complications and pain-related outcomes. Growth mixture modeling was used to construct pain trajectories. RESULTS: The first trajectory is characterized by 185 patients (78.1%) with mild pain intensity across the 12 month period. The second is characterized by 32 patients (7.5%) with moderate pain intensity immediately after surgery which decreases markedly by 3 months and remains low at the 12 month follow-up. The final trajectory is characterized by 20 patients (8.4%) with moderate pain intensity immediately after surgery which persists at 12 months. Patients with moderate to severe postoperative pain intensity were much more likely to develop CPSP compared to patients with mild pain intensity. Initial pain intensity levels immediately following surgery as well as levels of pain catastrophizing at baseline were predicting pain trajectory membership. None of the surgical or anesthetic-related variables were significantly associated with pain trajectory membership. CONCLUSION: Patients who undergo thoracic surgery can have postoperative pain that follows one of the three different types of trajectories. Higher levels of immediate postoperative pain and preoperative pain catastrophizing were associated with moderately severe CPSP.

Engagement with Manage My Pain mobile health application among patients at the Transitional Pain Service.

OBJECTIVE: Mobile health platforms have become an important component of pain self-management programs and hundreds of mobile applications are commercially available for patients to monitor pain. However, few of these applications have been developed in collaboration with healthcare professionals or have been critically evaluated. Manage My Pain is a user-driven mobile health platform developed by ManagingLife in collaboration with clinician researchers. Manage My Pain allows patients to keep a "pain record" and supports communication of this information with clinicians. The current report describes a user engagement study of Manage My Pain among patients at the Transitional Pain Service (TPS) at Toronto General Hospital, a multidisciplinary clinic for patients at high risk of developing postsurgical pain. METHODS: Patients at the TPS were encouraged to register on Manage My Pain as one component of a larger, non-randomized prospective study of treatment predictors and treatment enhancement. Uptake of the application and rates of registration, use, and retention were tracked for 90 days. RESULTS: Of the 196 patients who consented to the larger study, 132 (67%) also provided consent to the Manage My Pain component, indicating that they found this to be an acceptable treatment adjunct, and 119 (61%) completed registration. Of those who used the app, 67.9% and 43.2% continued to use Manage My Pain beyond 30 and 90 days, respectively. On average, users engaged with the app for 93.14 days (SD = 151.9 days) logged an average of 47.39 total records (SD = 136.1). CONCLUSIONS: Manage My Pain was found acceptable by a majority of patients at an academic pain management program. Rates of user registration and retention were favorable compared to those reported by other applications. Further research is needed to develop strategies to retain users and maximize patient benefit.

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.

Hyperbaric Oxygen for Radiation Necrosis of the Brain.

INTRODUCTION: Hyperbaric oxygen therapy (HBOT) shows promising results in treating radionecrosis (RN) but there is limited evidence for its use in brain RN. The purpose of this study is to report the outcomes of using HBOT for symptomatic brain RN at a single institution. METHODS: This was a retrospective review of patients with symptomatic brain RN between 2008 and 2018 and was treated with HBOT. Demographic data, steroid use, clinical response, radiologic response and toxicities were collected. The index time for analysis was the first day of HBOT. The primary endpoint was clinical improvement of a presenting symptom, including steroid dose reduction. RESULTS: Thirteen patients who received HBOT for symptomatic RN were included. The median time from last brain radiation therapy to presenting symptoms of brain RN was 6 months. Twelve patients (92%) had clinical improvement with median time to symptom improvement of 33 days (range 1-109 days). One patient had transient improvement after HBOT but had recurrent symptomatic RN at 12 months. Of the eight patients with evaluable follow-up MRI, four patients had radiological improvement while four had stable necrosis appearance. Two patients had subsequent deterioration in MRI appearances, one each in the background of initial radiologic improvement and stability. Median survival was 15 months with median follow-up of 10 months. Seven patients reported side effects attributable to HBOT (54%), four of which were otologic in origin. CONCLUSIONS: HBOT is a safe and effective treatment for brain RN. HBOT showed clinical and radiologic improvement or stability in most patients. Prospective studies to further evaluate the effectiveness and side effects of HBOT are needed.

Utilisation de l'oxygénothérapie hyperbare à la suite de séances de radiothérapie entraînant la mort du tissu cérébral. Introduction: Si l'oxygénothérapie hyperbare (OHB) laisse entrevoir des résultats prometteurs dans le traitement des radionécroses (RN), les preuves demeurent limitées quant à son utilisation dans le cas de RN du cerveau. L'objectif de cette étude est de présenter des résultats de recherche liés, dans un seul établissement de santé, à l'utilisation de l'OHB dans le cas de RN symptomatiques du cerveau. Méthodes: Pour ce faire, nous avons effectué une analyse rétrospective des dossiers de patients atteints de RN symptomatiques du cerveau entre 2008 et 2018 et ayant été traités lors de séances d'OHB. Nous avons aussi recueilli des données de nature démographique et d'autres portant sur l'utilisation de stéroïdes, sur la réponse clinique et radiologique des patients et sur les toxicités. Le point de départ (index time) de notre étude a été la première séance d'OHB alors que son principal indicateur de résultat a été l'amélioration sur le plan clinique d'un symptôme particulier, ce qui a inclus une réduction des doses de stéroïdes. Résultats: Au total, treize patients atteints de RN symptomatiques ont été inclus dans cette étude. Le temps médian entre une ultime séance de radiothérapie et l'apparition de symptômes de RN a été de 6 mois. Douze patients (92 %) ont donné à voir une amélioration de leur état médical, la période médiane d'amélioration de leurs symptômes étant de 33 jours (étendue : 1­109 jours). On a observé chez un seul patient une amélioration transitoire à la suite de séances d'OHB, les symptômes de RN étant réapparus au douzième mois. Sur les huit patients ayant subi un examen d'imagerie de suivi, quatre d'entre eux ont montré des signes d'amélioration sur le plan radiologique tandis que quatre autres ont donné à voir une RN stable. Fait à noter, deux patients chez qui l'on avait observé une amélioration radiologique initiale ou une stabilité de leur état ont montré une détérioration ultérieure à la suite d'un examen d'IRM. Le taux de survie médian de ces patients et leur suivi médian ont été respectivement de 15 mois et de 10 mois. Enfin, sept d'entre eux ont signalé des effets secondaires attribuables à l'OHB, dont quatre d'origine otologique. Conclusions: L'OHB demeure un traitement efficace et sécuritaire dans le cas des RN du cerveau. Elle a permis d'observer chez la plupart des patients une amélioration clinique et radiologique ou à tout le moins une stabilité de leurs symptômes. Cela dit, des études prospectives sont nécessaires afin de pouvoir évaluer plus en profondeur son efficacité et ses effets secondaires.