Prefrontal cortex activation during incremental inspiratory loading in healthy participants.

We aimed to investigate whether changes in prefrontal cortex (PFC) oxyhemoglobin (O2Hb) and deoxyhemoglobin (HHb) associates with inspiratory muscle effort during inspiratory threshold loading (ITL) in healthy participants. Participants performed an incremental ITL. Breathing pattern, partial pressure of end-tidal CO2 (PETCO2), mouth pressure and O2Hb and HHb over the right dorsolateral PFC, sternocleidomastoid (SCM), and diaphragm/intercostals (Dia/IC) were monitored. Fourteen healthy participants (8 men; 29 ± 5 years) completed testing. Dyspnea was higher post- than pre-ITL (5 ± 1 vs. 0 ± 1, respectively; P<0.05). PFC O2Hb increased (P < 0.001) and HHb decreased (P = 0.001) at low loads but remained stable with increasing ITL intensities. PFC total hemoglobin increased at task failure compared to rest. SCM HHb increased throughout increasing intensities. SCM and Dia/IC total hemoglobin increased in the at task failure compared to rest. PETCO2 did not change (P = 0.528). PFC is activated early during the ITL but does not show central fatigue at task failure despite greater dyspnea and an imbalance of SCM oxygen demand and delivery.

A Comparison of Acute Complications and Mortality Between Geriatric Knee and Hip Fractures: A Matched Cohort Study.

INTRODUCTION: To compare acute complication and mortality rates for operatively treated, closed, isolated, low-energy geriatric knee fractures (distal femur [DFF] or tibial plateau [TPF]) with hip fractures (HFs). METHODS: This is a retrospective cohort study using the American College of Surgeons National Surgical Quality Improvement Program. We identified all patients ≥ 70 years from 2011 to 2016 who underwent surgery for DFF, TPF, or HF. We recorded patient demographics, functional status, complications, and mortality. We matched DFF:TPF:HF patients on a 1:1:10 ratio based on age, sex, body mass index, baseline functional status, and comorbidity. We used the chi square, Fisher exact, and Mann Whitney U tests to compare unadjusted differences between groups and multivariable logistic regression to compare the risk of complications, readmission, or death while adjusting for relevant covariates. RESULTS: When compared with HF, patients in the DFF and TPF groups had longer length of stay and time to index surgery and were more likely to be discharged home. The rate of deep vein thrombosis was significantly higher in the TPF group (TPF = 3.9%, DFF = 1.3%, and HF = 1.2%, P = 0.005). CONCLUSION: Geriatric knee fractures pose a similar risk of acute complications, mortality, and readmission compared with patients with HF. Future studies investigating strategies to decrease risk in this patient cohort are warranted. LEVEL OF EVIDENCE: Therapeutic Level III.

Wear Rates of XLPE Nearly 50% Lower Than Previously Thought After Adjusting for Initial Creep: An RCT Comparing 4 Bearing Combinations.

BACKGROUND: The ideal bearing combination for total hip arthroplasty (THA) remains debatable. Highly cross-linked polyethylene (XLPE) is widely used, but long-term wear rates are not fully known, nor is how much the initial "creep," if any, affects overall wear. Additionally, the use of oxidized zirconium (OxZir) is purported to lower polyethylene wear rates, but this has not been proven. We present the 10-year data of a cohort of patients who underwent THA. Patients were prospectively randomized to 1 of 4 bearing combinations: a conventional ultra-high molecular weight polyethylene (UHMWPE) or XLPE acetabular liner coupled with either a cobalt-chromium (CoCr) or OxZir femoral head. The aims of the study were to (1) assess the extent to which creep affected overall wear rates and (2) assess wear rates between OxZir and CoCr with polyethylene. METHODS: A total of 92 hips (92 patients) between the ages of 22 and 65 years (mean, 52.2 ± 9.3 years) were randomized to 4 groups. At 10 years, 70 (76%) of the hips were available for analysis; patients who had undergone revision, had died, or were lost to follow-up were excluded from final analysis. Radiographic analysis was performed using a validated digital assessment program to determine linear, volumetric, and directional wear of the polyethylene for all 4 bearing couples. Radiographic assessments were performed immediately postoperatively, at 6 and 12 weeks, and then annually for a minimum of 10 years. RESULTS: XLPE had significantly lower wear rates than UHMWPE. Once creep was eliminated, annual and overall wear rates were nearly 50% lower than have been previously reported. This was proportionally more important in the XLPE group than in the UHMWPE group. There was a nonsignificant trend toward a lower wear rate with OxZir heads. CONCLUSIONS: Creep plays a notably more important role than first thought. Once creep was eliminated, the overall wear rate was even lower than previously assumed. This has important implications for the overall survivorship of hip arthroplasty implants. LEVEL OF EVIDENCE: Therapeutic Level I. See Instructions for Authors for a complete description of levels of evidence.

The effects of hypoxia on muscle deoxygenation and recruitment in the flexor digitorum superficialis during submaximal intermittent handgrip exercise.

BACKGROUND: Decreased oxygenation of muscle may be accentuated during exercise at high altitude. Monitoring the oxygen saturation of muscle (SmO2) during hand grip exercise using near infrared spectroscopy during acute exposure to hypoxia could provide a model for a test of muscle performance without the competing cardiovascular stresses that occur during a cycle ergometer or treadmill test. The purpose of this study was to examine and compare acute exposure to normobaric hypoxia versus normoxia on deoxygenation and recruitment of the flexor digitorum superficialis (FDS) during submaximal intermittent handgrip exercise (HGE) in healthy adults. METHODS: Twenty subjects (11 M/9 F) performed HGE at 50% of maximum voluntary contraction, with a duty cycle of 2 s:1 s until task failure on two occasions one week apart, randomly assigned to normobaric hypoxia (FiO2 = 12%) or normoxia (FiO2 = 21%). Near-infrared spectroscopy monitored SmO2, oxygenated (O2Hb), deoxygenated (HHb), and total hemoglobin (tHb) over the FDS. Surface electromyography derived root mean square and mean power frequency of the FDS. RESULTS: Hypoxic compared to normoxic HGE induced a lower FDS SmO2 (63.8 ± 2.2 vs. 69.0 ± 1.5, p = 0.001) and both protocols decreased FDS SmO2 from baseline to task failure. FDS mean power frequency was lower during hypoxic compared to normoxic HGE (64.0 ± 1.4 vs. 68.2 ± 2.0 Hz, p = 0.04) and both decreased mean power frequency from the first contractions to task failure (p = 0.000). Under both hypoxia and normoxia, HHb, tHb and root mean square increased from baseline to task failure whereas O2Hb decreased and then increased during HGE. Arterial oxygen saturation via pulse oximetry (SpO2) was lower during hypoxia compared to normoxia conditions (p = 0.000) and heart rate and diastolic blood pressure only demonstrated small increases. Task durations and the tension-time index of HGE did not differ between normoxic and hypoxic trials. CONCLUSION: Hypoxic compared to normoxic HGE decreased SmO2 and induced lower mean power frequency in the FDS, during repetitive hand grip exercise however did not result in differences in task durations or tension-time indices. The fiber type composition of FDS, and high duty cycle and intensity may have contributed greater dependence on anaerobiosis.

Mortality Rate of Geriatric Acetabular Fractures Is High Compared With Hip Fractures. A Matched Cohort Study.

OBJECTIVES: Compare acute complication and mortality rates of geriatric patients with acetabular fractures (AFs) matched to hip fractures (HFs). DESIGN: Retrospective cohort study. SETTING: American College of Surgeons National Surgical Quality Improvement Project. PATIENTS: Using Current Procedural Terminology codes, the American College of Surgeons National Surgical Quality Improvement Project registry was used to identify all patients ≥60 years from 2011 to 2016 treated for AFs undergoing open reduction internal fixation (ORIF) and HFs (undergoing ORIF, hemiarthroplasty, or cephalomedullary nail). OUTCOME MEASUREMENTS: Patient characteristics, comorbidities, functional status, acute complications, and mortality rates were recorded. Patients were matched 1:5 (AF:HF). Chi-square, Fisher exact, and Mann-Whitney U tests were used to compare groups, and multivariable logistic regression was used to compare the risk of complications or death while adjusting for relevant covariates. RESULTS: A total of 303 AF patients (age: 78.2 ± 9.2 years/59.7% females/27.1% wall, 28.4% one column and 45.2% 2 columns ORIF) were matched to 1511 HF patients (age: 78.3 ± 9.1 years/60.2% females/37.2% hemiarthroplasty, 16.3% ORIF and 47.4% cephalomedullary nail). Length of stay (8.4 ± 7.1 vs. 6.4 ± 5.9 days) and time to surgery [(TS) 2.3 ± 1.8 versus 1.2 ± 1.4 days] were longer in the AF group (P < 0.01). Unadjusted mortality rates were nonsignificantly higher for AFs versus HFs (6.6% vs. 4.6%, P = 0.14). After covariable adjustment, the risk of mortality was significantly higher for AFs versus HFs (odds ratio: 1.89, 95% confidence interval: 1.07-3.35). CONCLUSION: Geriatric AFs pose a significantly higher adjusted mortality risk when compared with HF patients. Strategies to mitigate risk factors in this population are warranted. LEVEL OF EVIDENCE: Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Neck and Inspiratory Muscle Recruitment during Inspiratory Loading and Neck Flexion.

PURPOSE: This study aimed to compare muscle activation of the diaphragm (DIA), scalenes (SA), parasternal intercostals (PS), and sternomastoid (SM) during submaximal intermittent neck flexion (INF) versus submaximal inspiratory threshold loading (ITL) until task failure in healthy adults. METHODS: Twelve healthy adults performed submaximal ITL or INF tests in random order for 2 d. Surface electromyography was monitored to acquire root mean square (RMS) and median power frequency (MPF) from the SA, PS, SM, and DIA. Maximal inspiratory pressures and maximal voluntary contraction for neck flexion were determined. Next, participants performed the first submaximal test-ITL or INF-targeting 50% ± 5% of the maximal inspiratory pressure or maximal voluntary contraction, respectively, until task failure. After a rest, they performed the other test until task failure. Two days later, they performed ITL and INF but in the opposite order. The Borg scale assessed breathlessness and perceived exertion. RESULTS: Endurance times for ITL and INF were 38.1 and 26.3 min, respectively. INF activated three of four inspiratory muscles at higher average RMS (PS, SM, and SA) and at different MPF (PS, SM, and DIA but not SA) compared with ITL. During ITL, RMS did not change in the four inspiratory muscles over time, but MPF decreased in PS, SM, and SA (P < 0.04). In contrast, RMS increased in three of four inspiratory muscles (SM, PS, and SA) during INF, but MPF did not change throughout its duration. Borg rating was 3.9-fold greater than ITL compared with INF. CONCLUSION: At a similar percentage of maximal load, INF evokes greater activation of primary muscles of inspiration (PS and SA) and a major accessory muscle of inspiration (SM) compared with ITL during a prolonged submaximal protocol.

Oxyhemoglobin changes in the prefrontal cortex in response to cognitive tasks: a systematic review.

PURPOSE OF THE STUDY: the aim of this study was to synthesize PFC fNIRS outcomes on the effects of cognitive tasks compared to resting/baseline tasks in healthy adults from studies utilizing a pre/post design. MATERIAL AND METHODS: original research studies were searched from seven databases (MEDLINE, EMBASE, CENTRAL, CINAHL, SCOPUS, PEDro and PubMed). Subsequently, two independent reviewers screened the titles and abstracts followed by full-text reviews to assess the studies' eligibility. RESULTS: eleven studies met the inclusion criteria and had data abstracted and quality assessed. Methodology varied considerably and yet cognitive tasks resulted in the ΔO2Hb increasing in 8 of the 11 and ΔHHb decreasing in 8 of 8 studies that reported this outcome. The cognitive tasks from 10 of the 11 studies were classified as "Working Memory" and "Verbal Fluency Tasks". CONCLUSIONS: although, the data comparison was challenging provided the heterogeneity in methodology, the results across studies were similar.

Inspiratory Muscle Rehabilitation in Critically Ill Adults. A Systematic Review and Meta-Analysis.

RATIONALE: Respiratory muscle weakness is common in critically ill patients; the role of targeted inspiratory muscle training (IMT) in intensive care unit rehabilitation strategies remains poorly defined. OBJECTIVES: The primary objective of the present study was to describe the range and tolerability of published methods for IMT. The secondary objectives were to determine whether IMT improves respiratory muscle strength and clinical outcomes in critically ill patients. METHODS: We conducted a systematic review to identify randomized and nonrandomized studies of physical rehabilitation interventions intended to strengthen the respiratory muscles in critically ill adults. We searched the MEDLINE, Embase, HealthSTAR, CINAHL, and CENTRAL databases (inception to September Week 3, 2017) and conference proceedings (2012 to 2017). Data were independently extracted by two authors and collected on a standardized report form. RESULTS: A total of 28 studies (N = 1,185 patients) were included. IMT was initiated during early mechanical ventilation (8 studies), after patients proved difficult to wean (14 studies), or after extubation (3 studies), and 3 other studies did not report exact timing. Threshold loading was the most common technique; 13 studies employed strength training regimens, 11 studies employed endurance training regimens, and 4 could not be classified. IMT was feasible, and there were few adverse events during IMT sessions (nine studies; median, 0%; interquartile range, 0-0%). In randomized trials (n = 20), IMT improved maximal inspiratory pressure compared with control (15 trials; mean increase, 6 cm H2O; 95% confidence interval [CI], 5-8 cm H2O; pooled relative ratio of means, 1.19; 95% CI, 1.14-1.25) and maximal expiratory pressure (4 trials; mean increase, 9 cm H2O; 95% CI, 5-14 cm H2O). IMT was associated with a shorter duration of ventilation (nine trials; mean difference, 4.1 d; 95% CI, 0.8-7.4 d) and a shorter duration of weaning (eight trials; mean difference, 2.3 d; 95% CI, 0.7-4.0 d), but confidence in these pooled estimates was low owing to methodological limitations, including substantial statistical and methodological heterogeneity. CONCLUSIONS: Most studies of IMT in critically ill patients have employed inspiratory threshold loading. IMT is feasible and well tolerated in critically ill patients and improves both inspiratory and expiratory muscle strength. The impact of IMT on clinical outcomes requires future confirmation.

Deoxygenation of inspiratory muscles during cycling, hyperpnoea and loaded breathing in health and disease: a systematic review.

Assessing inspiratory muscle deoxygenation and blood flow can provide insight into anaerobic stress, recruitment strategies and mechanisms of inspiratory muscle limitation. Therefore, this review aimed to synthesize measurements of inspiratory muscle oxyhaemoglobin (O2 Hb), deoxyhaemoglobin (HHb), blood volume and flow of the inspiratory muscles acquired via near-infrared spectroscopy (NIRS) during cycling, hyperpnoea and loaded breathing in healthy non-athletes, healthy athletes and patients with chronic obstructive pulmonary disease (COPD) or chronic heart failure (CHF). Searches were performed on Medline and Medline in-process, EMBASE, Central, Sportdiscus, PubMed and Compendex. Reviewers independently abstracted articles and assessed their quality using the modified Downs and Black checklist. Of the 644 articles identified, 21 met the inclusion criteria. Studies evaluated non-athletes (n = 9), athletes (n = 5), COPD (n = 2) and CHF (n = 5). The sample was 90% male and 73% were non-athletes and athletes. Interventions included cycle ergometry, hyperpnoea, loaded breathing, elbow flexor loading and combined loaded breathing and ergometry. Athletes and patients with CHF or COPD demonstrated deoxygenation of inspiratory accessory muscles that was often an opposite or exaggerated pattern compared to non-athletes. O2 Hb decreased and HHb increased significantly in inspiratory muscles during cycle ergometry and loaded breathing with accentuated changes during combined ergometry and loaded breathing. During different regimens of hyperpnoea or loaded breathing, comparisons of inspiratory muscles demonstrated that the sternocleidomastoid deoxygenated more than the intercostals, parasternals or scalenes. Evaluating inspiratory muscle deoxygenation via NIRS can inform mechanisms of inspiratory muscle limitation in non-athletes, athletes and patients with CHF or COPD.

Frutalin reduces acute and neuropathic nociceptive behaviours in rodent models of orofacial pain.

Orofacial pain is a highly prevalent clinical condition, yet difficult to control effectively with available drugs. Much attention is currently focused on the anti-inflammatory and antinociceptive properties of lectins. The purpose of this study was to evaluate the antinociceptive effect of frutalin (FTL) using rodent models of inflammatory and neuropathic orofacial pain. Acute pain was induced by formalin, glutamate or capsaicin (orofacial model) and hypertonic saline (corneal model). In one experiment, animals were pretreated with l-NAME and naloxone to investigate the mechanism of antinociception. The involvement of the lectin domain in the antinociceptive effect of FTL was verified by allowing the lectin to bind to its specific ligand. In another experiment, animals pretreated with FTL or saline were submitted to the temporomandibular joint formalin test. In yet another, animals were submitted to infraorbital nerve transection to induce chronic pain, followed by induction of thermal hypersensitivity using acetone. Motor activity was evaluated with the rotarod test. A molecular docking was performed using the TRPV1 channel. Pretreatment with FTL significantly reduced nociceptive behaviour associated with acute and neuropathic pain, especially at 0.5 mg/kg. Antinociception was effectively inhibited by l-NAME and d-galactose. In line with in vivo experiments, docking studies indicated that FTL may interact with TRPV1. Our results confirm the potential pharmacological relevance of FTL as an inhibitor of orofacial nociception in acute and chronic pain mediated by TRPA1, TRPV1 and TRPM8 receptor.