Transition-metal-catalyzed domino reactions of strained bicyclic alkenes.

This review presents a comprehensive overview of transition-metal-catalyzed domino reactions of strained bicyclic alkenes, including both homo- and heterobicyclic alkenes. These compounds are important synthons in organic synthesis, providing an important platform for the construction of biologically/medicinally significant compounds which bear multiple stereocenters. The review has been divided according to the metal used in the reaction. An overview of the substrate scope, reaction conditions, and their potential applications in organic synthesis is discussed. A comprehensive outlook on the reactivity paradigms of homo- and heterobicyclic alkenes is discussed and should shed light on future directions for further development in this field.

Relationship Between Preoperative Nutritional Status and Predicting Short-Term Complications Following Revision Total Hip Arthroplasty.

BACKGROUND: The association between malnutrition and complications following primary total joint arthroplasty is well-delineated; however, nutritional status has yet to be explored specifically in revision total hip arthroplasty (THA). Therefore, our objective was to examine if a patient's nutritional status based on body mass index, diabetic status, and serum albumin predicted complications following a revision THA. METHODS: A retrospective national database review identified 12,249 patients who underwent revision THA from 2006 to 2019. Patients were stratified based on body mass index (<18.5 = underweight, 18.5-29.9 = healthy/overweight, ≥30 = obese), diagnosis of diabetes (no diabetes, insulin-dependent diabetes mellitus (IDDM), non-insulin-dependent diabetes mellitus), and preoperative serum albumin (<3.5 = malnourished, ≥3.5 = non-malnourished). Multivariate analyses were performed using chi-square tests and multiple logistic regressions. RESULTS: In all groups including underweight (1.8%), healthy/overweight (53.7%), and obese (44.5%), those without diabetes were less likely to be malnourished (P < .001), while those with IDDM had a higher rate of malnutrition (P < .001). Underweight patients were significantly more malnourished compared to healthy/overweight or obese patients (P < .05). Malnourished patients had an increased risk of wound dehiscence/surgical site infections (P < .001), urinary tract infection (P < .001), requiring a blood transfusion (P < .001), sepsis (P < .001), and septic shock (P < .001). Malnourished patients also have worse postoperative pulmonary and renal function. CONCLUSION: Patients who are underweight or have IDDM are more likely to be malnourished. The risk of complications within 30 days of surgery following revision THA significantly increases with malnutrition. This study shows the utility of screening underweight and IDDM patients for malnutrition prior to revision THA to minimize complications.

Effects of Premixing Betamethasone and Lidocaine on Chondrocyte Inflammation in an In Vitro Model.

BACKGROUND: It is common practice for hand surgeons to premix corticosteroids with a local anesthetic and store the mixture in pre-loaded syringes for rapid use during clinic. However, any possible loss of efficacy with this practice has never been studied. The purpose of this study, therefore, is to determine whether premixing betamethasone sodium phosphate/betamethasone acetate (BSP) and lidocaine (L) at different time intervals from injection has diminishing anti-inflammatory effects on chondrocytes in vitro. METHODS: Human articular chondrocytes were partitioned into six groups: two controls and four experimental conditions. The negative control had growth media only. The positive control had growth media and inflammatory cytokines (interleukin-1ß and oncostatin M). Experimental conditions were additionally treated with BSP alone or BSP mixed with lidocaine (BSP + L) at the time of treatment (0 hours), or at 4 or 24 hours prior. Relative expressions of inflammatory genes were measured. RESULTS: Relative to the positive control, chondrocytes in all experimental conditions decreased expression of TNF-α, MMP-3, and ADAMTS-4. Chondrocytes exposed to BSP only or BSP + L at 4 hours or 24 hours prior to treatment decreased expression of IL-8. Chondrocytes exposed to BSP only or BSP + L at 0 hours or 4 hours prior to treatment decreased expression of MMP-1. There were no significant differences in expression of IL-6 or MMP-13. CONCLUSIONS: Treatment with BSP + L prepared in pre-loaded syringes at varying time intervals up to 24 hours prior to injection does not significantly impact the ability of the mixture to reduce expression of certain key inflammatory mediators in vitro.

The Effects of Autologous Fat Transfer in an In Vitro Model of Basal Joint Osteoarthritis.

PURPOSE: Basal joint osteoarthritis (OA) is a highly prevalent and debilitating condition. Recent clinical evidence suggests that autologous fat transfer (AFT) may be a promising, minimally invasive treatment for this condition. However, the mechanism of action is not fully understood. It is theorized that AFT reduces inflammation in the joint, functions to regenerate cartilage, or acts as a mechanical buffer. The purpose of this study was to better understand the underlying mechanism of AFT using an in vitro model. We hypothesize that the addition of stromal vascular fraction (SVF) cells will cause a reduction in markers of inflammation. METHODS: Articular chondrocytes were expanded in culture. Liposuction samples were collected from human subjects and processed similarly to AFT protocols to isolate SVF rich in adipose-derived stem cells. A control group was treated with standard growth media, and a positive control group (OA group) was treated with inflammatory cytokines. To mimic AFT, experimental groups received inflammatory cytokines and either a low or high dose of SVF. Expression of relevant genes was measured, including interleukin (IL)-1ß, IL-1 receptor antagonist, and matrix metalloproteinases (MMP). RESULTS: Compared to the OA group, significant decreases in IL-1ß, MMP3, and MMP13 expression on treatment day 3 were found in the high-dose SVF group, while MMP13 expression was also significantly decreased in the low-dose SVF group on day 3. CONCLUSIONS: In this study, we found that SVF treatment reduced expression of IL-1ß, MMP3, and MMP13 in an in vitro model of OA. These results suggest that an anti-inflammatory mechanism may be responsible for the clinical effects seen with AFT in the treatment of basal joint OA. CLINICAL RELEVANCE: An anti-inflammatory mechanism may be responsible for the clinical benefits seen with AFT for basal joint arthritis.

Effect of Real-Time Feedback on Power Output Using a Novel Smart-Resisted Sled Push.

Prior studies have demonstrated the beneficial effects of real-time data feedback (RTF) on athletic performance and motivation. Despite this evidence, the lack of practical means to implement RTF has hindered its widespread adoption. Recently, a smart-resisted sled push was developed to improve athletic power by utilizing electromagnetic motors as a resistance mechanism, coupled with an RTF display. Thirty healthy college-aged male football players were recruited in this randomized, crossover designed study to examine the efficacy of the RTF to improve power output. Participants were randomized into either group 1 (receiving RTF first then no RTF) or group 2 (receiving no RTF first then RTF) during six, 10-meter sled pushes with 3 min rest intervals. The first three pushes were set to an easier level (L1) and the last three were set to a resistance level twice that of the first three runs (L2). A one-month washout period was enforced. For trials 1-3 (L1) (p = 0.026, t = -2.34, ES = -0.428) and 4-6 (L2) (p = 0.035, t = -2.22, ES = -0.405), peak power output (the average peak power output over the course of trials 1-3 and 4-6) was greater in both groups when receiving RTF compared to no-RTF. These findings demonstrate the effectiveness of RTF in augmenting power output during performance training.

What is a better value for your time? Anterior cervical discectomy and fusion versus cervical disc arthroplasty.

Introduction: Compared to anterior cervical discectomy and fusion (ACDF), the motion preservation of cervical disc arthroplasty (CDA) provides an attractive alternative with similar short-term results. However, there is a paucity of the economics of performing CDA over ACDF. Study Design: This was retrospective study. Objective: The objective of this study is to evaluate relative-value-units (RVUs), operative time, and RVUs-per-minute between single-level ACDF and CDA. Secondary outcomes included 30-day readmission, reoperation, and morbidity. Methods: Adults who underwent ACDF or CDA in 2011-2019 National Surgical Quality Improvement Program database datasets. Multivariate quantile regression was utilized. Results: There were 26,595 patients (2024 CDA). ACDF patients were older, more likely to be female, discharged to inpatient rehabilitation, and have a history of obesity, smoking, diabetes, steroid use, and the American Society of Anesthesiologists-class ≥3. ACDF had greater median RVUs-per-case (41.2 vs. 24.1) and RVUs-per-minute (0.36 vs. 0.27), despite greater operative-time (109 min vs. 92 min) (P < 0.001). ACDF predicted a 16.9 unit increase in median RVUs per case (P < 0.001, confidence interval [CI]95: 16.3-17.5), an 8.81 min increase in median operative time per case (P < 0.001, CI95: 5.69-11.9), and 0.119 unit increase in median RVUs-per-minute (P < 0.001, CI95: 0.108-0.130). ACDF was associated with greater unadjusted rates of readmission (3.2% vs. 1.4%) morbidity (2.3% vs. 1.1%) (P < 0.001), but similar rates of reoperation (1.3% vs. 0.8%, P = 0.080). After adjusting for significant patient-related and procedural factors, readmission (odds ratio [OR] = 0.695, P = 0.130, CI95: 0.434-1.113) and morbidity (OR = 1.102, P = 0.688, CI95: 0.685-1.773) was similar between ACDF and CDA. Conclusions: Median RVUs-per-minute increased by 0.119 points for ACDF over CDA, or $257.7/h for each additional-hour of surgery. Adjusted 30-day outcomes were similar between procedures. Reimbursement for CDA does not appear to be in line with ACDF and may be a barrier to widespread usage.

Liposomal bupivacaine does not decrease postoperative opioid use or length of hospital stay in patients undergoing anterior cervical discectomy and fusion.

Background: Despite its widespread use, definitive data demonstrating the efficacy of liposomal bupivacaine (LB) is limited especially in patients undergoing anterior cervical discectomy and fusion (ACDF). Therefore, this investigation examined whether ACDF patients who received intra-operative LB (LB cohort) exhibited decreased post-operative opioid use and lengths of hospital stay (LOS) compared to ACDF patients who did not receive intra-operative LB (controls). Methods: Eighty-two patients who underwent primary ACDF by a single surgeon from 2016 to 2019 were identified from an institutional database. Fifty-nine patients received intra-operative LB while twenty-three did not. Patient characteristics, medical comorbidities, complications, post-operative opioid consumption, and LOS data were collected. Results: The LB cohort did not require fewer opioids on post-operative day (POD) 0, POD1, POD2, or throughout the hospital course after normalizing by LOS (total per LOS). The number of cervical vertebrae involved in surgery, but not LB use, predicted opioid consumption on POD0, POD1, and total per LOS. For every vertebral level involved, 242 additional morphine milligram equivalents (MME) were consumed on POD0, 266 additional MME were utilized on POD1, and 130 additional MME were consumed in total per LOS. Conclusions: ACDF patients who received intra-operative LB did not require fewer post-operative opioids or exhibit a decreased LOS compared to controls. Patients whose procedures involved a greater number of cervical vertebrae were associated with greater opioid consumption on POD0, POD1, and total per LOS. ACDF patients, especially those who had a high number of vertebrae involved, may require alternative analgesia to LB.

Knee Disarticulation Versus Transfemoral Amputation: The Prosthetist's Perspective.

OBJECTIVES: The objective of this study was to survey a broad group of prosthetists on their experience with amputees with knee disarticulation (KD) and transfemoral amputation (TFA) to determine their preference of amputation level, opinions on patient preference, and common problematic issues to guide decision-making for patients and surgeons faced with the decision of a high-level lower extremity amputation. DESIGN: This is a survey-based study. INTERVENTION: A blinded electronic mail survey was completed by 102 prosthetists. MAIN OUTCOME MEASUREMENTS: Each prosthetist was asked (1) what amputation level (KD or TFA) do they prefer and why and (2) which amputation level do they believe patients prefer and why. RESULTS: There was no consensus among prosthetists regarding amputation level preference. Fifty-four (53%) prosthetists preferred KD and 48 (47%) preferred TFA. Fifty-five (54%) prosthetists believed patients preferred TFA and 47 (46%) believed patients preferred KD. Amputation level preference often depended on age, functional goals, and concerns with cosmesis. The most common benefits given for KD over TFA included distal-end weight-bearing (n = 53), a lower subischial socket (n = 43), and better function (n = 30). The most common disadvantages given for KD over TFA included component limitations due to space available below amputation (n = 56), poor cosmesis (n = 49), an asymmetrical knee axis (n = 42), and difficulties with sitting/standing (n = 13). CONCLUSION: No consensus exists between prosthetists regarding preference for KD versus TFA. The advantages and disadvantages of KD reported in this study, along with the associated decision tree, can be used for future counseling of patient's faced with high-level lower extremity amputations.

Visualization Tools for Genomic Conservation.

SynVisio and Accusyn ( genomevis.usask.ca ) are freely available web-based tools for visualizing genomic conservation that provide easy-to-access visualizations for researchers to interact with their datasets and change parameters in real time to carry out synteny exploration and analysis through multiple coordinated visual representations. The tools use standard file formats and outputs from existing synteny detection systems such as MCScanX or DAGChainer, and provide several features that are valuable for large-scale genomic analysis: a range of visualization scales from full genomes down to single collinearity blocks; single-level and multiple-level plots that enable the analysis of more than two genomic regions; annotation tracks that can be loaded using standard BedGraph files; several techniques for reducing visual clutter in visualizations; the ability to download high-quality images of the visualizations; and a snapshot panel for storing configurations of the interface for later revisitation.

Muscle Activity During Immersive Virtual Reality Exergaming Incorporating an Adaptive Cable Resistance System.

The purpose of this exploratory study was to characterize muscle activation via surface electromyography (sEMG), user-perceived exertion, and enjoyment during a 30-minute session of immersive virtual reality (IVR) cable resistance exergaming. Ten healthy, college-aged males completed a signature 30-minute exergaming session using an IVR adaptive cable resistance system that incorporated six traditional compound exercises. Muscle activation (sEMG) was captured during the session with a wearable sEMG system. Rated of Perceived Exertion (RPE) and Physical Activity Enjoyment Scale (PACES) were recorded following the session. Pectoralis major showed the highest activation during chest press, deltoids showed the highest activation on overhead press, latissimus dorsi showed the highest activation during lat pulldown and row exercises, hamstrings were the most activated muscles during Romanian deadlift, and glutes showed the highest activity during squats. RPE and PACES mean scores were 14 (1) and 4.27 (0.38), respectively. IVR exergaming with resistance cable training provides an enjoyable experience and distracts practitioners from exertion while exercising at a high intensity. Results from this study suggest similar muscle activation responses compared to traditional resistance exercises as demonstrated with prior evidence. This novel form of exercise might have important repercussions for improving health outcomes among those who find it challenging to adhere to and enjoy exercise routines, as well as with little knowledge on how to progress in their resistance training. Further investigations are needed to explore long-term adaptations and to assess if IVR exergaming has additional benefits compared to traditional resistance training.

Lifestyle Modification Using a Wearable Biometric Ring and Guided Feedback Improve Sleep and Exercise Behaviors: A 12-Month Randomized, Placebo-Controlled Study.

Purpose: Wearable biometric monitoring devices (WBMD) show promise as a cutting edge means to improve health and prevent disease through increasing accountability. By regularly providing real-time quantitative data regarding activity, sleep quality, and recovery, users may become more aware of the impact that their lifestyle has on their health. The purpose of this study was to examine the efficacy of a biometric tracking ring on improving sleep quality and increasing physical fitness over a one-year period. Methods: Fifty-six participants received a biometric tracking ring and were placed in one of two groups. One group received a 3-month interactive behavioral modification intervention (INT) that was delivered virtually via a smartphone app with guided text message feedback (GTF). The other received a 3-month non-directive wellness education control (CON). After three months, the INT group was divided into a long-term feedback group (LT-GTF) that continued to receive GTF for another nine months or short-term feedback group (ST-GTF) that stopped receiving GTF. Weight, body composition, and VO2max were assessed at baseline, 3months, and 12months for all participants and additionally at 6 and 9months for the ST-GTF and LT-GTF groups. To establish baseline measurements, sleep and physical activity data were collected daily over a 30-day period. Daily measurements were also conducted throughout the 12-month duration of the study. Results: Over the first 3months, the INT group had significant (p<0.001) improvements in sleep onset latency, daily step count, % time jogging, VO2max, body fat percentage, and heart rate variability (rMSSD HRV) compared to the CON group. Over the next 9months, the LT-GTF group continued to improve significantly (p<0.001) in sleep onset latency, daily step count, % time jogging, VO2max, and rMSSD HRV. The ST-GTF group neither improved nor regressed over the latter 9months except for a small increase in sleep latency. Conclusion: Using a WBMD concomitantly with personalized education, encouragement, and feedback, elicits greater change than using a WBMD alone. Additionally, the improvements achieved from a short duration of personalized coaching are largely maintained with the continued use of a WBMD.

Physiological and Metabolic Requirements, and User-Perceived Exertion of Immersive Virtual Reality Exergaming Incorporating an Adaptive Cable Resistance System: An Exploratory Study.

Objective: To measure metabolic and physiological demand, subjective fatigue, and enjoyment during a signature 30-minute immersive virtual reality (IVR) adaptive cable resistance exergaming session. Methods: Fourteen healthy college-aged individuals (seven females) were initially acquainted with the IVR equipment and gameplay dynamics. Participants then underwent a 30-minute IVR exergaming session performing six different cable resistance exercises. A portable metabolic gas exchange analyzer concurrently assessed energy expenditure (EE) through indirect calorimetry while a chest-worn monitor captured heart rate (HR). Participants subsequently completed questionnaires, including the Borg scale for rating of perceived exertion (RPE), Physical Activity Enjoyment Scale (PACES), and Simulator Sickness Questionnaire (SSQ). Results: The mean EE, mean metabolic equivalent, and average total calories expended during the 30-minute session were 14.7 (standard deviation [SD] 2.8) kcal/minute, 12.9 (SD 0.5), and 440 (SD 84) kcals respectively. The mean HR was 176 (SD 3.1) beats per minute (bpm) with a mean max HR of 188 SD (SD 2.9) bpm. The combined training volume among all participants was 16,102 kg (SD 4137). Participants classified the IVR training session to be "somewhat hard-to-hard" with a RPE score of 14 (SD 1) while indicating the session to be "enjoyable" with a PACES score of 4.31 (SD 0.36). The participants did not report any cybersickness symptoms, demonstrating an average total SSQ score of 24.04 (SD 24.13). Conclusions: IVR exergaming incorporating cable resistance training elicits high EE and physiological demand with high enjoyment scores while attenuating perceived fatigue. The potential for IVR to elicit these acute training effects over long-term training periods warrants further investigation into its contribution to fitness and health.

COVID-19 Lockdowns: Exacerbating the Silent Pandemic.

The global medical community has exalted the vaccine as the champion solution to end the violent toll inflicted by COVID-19. While the role of vaccines cannot be undervalued in wide-scale intervention, presenting them as the sole solution exonerates individuals of the importance of taking ownership over their lifestyle choices. This editorial focuses on the importance of physical activity as a crucial component of COVID-19 prevention programs and a long-term investment against chronic diseases.

A Multidomain Approach to Assessing the Convergent and Concurrent Validity of a Mobile Application When Compared to Conventional Methods of Determining Body Composition.

Determining body composition via mobile application may circumvent limitations of conventional methods. However, the accuracy of many technologies remains unknown. This investigation assessed the convergent and concurrent validity of a mobile application (LS) that employs 2-dimensional digital photography (LS2D) and 3-dimensional photonic scanning (LS3D). Measures of body composition including circumferences, waist-to-hip ratio (WHR), and body fat percentage (BF%) were obtained from 240 healthy adults using LS and a diverse set of conventional methods-Gulick tape, bioelectrical impedance analysis (BIA), and skinfolds. Convergent validity was consistently high-indicating these methods vary proportionally and can thus reliably detect changes despite individual measurement differences. The span of the Limits of Agreement (LoA) using LS were comparable to the LoA between conventional methods. LS3D exhibited high agreement relative to Gulick tape in the measurement of WHR, despite poor agreement with individual waist and hip circumferences. In BF%, LS2D exhibited high agreement with BIA and skinfold methods, whereas LS3D demonstrated low agreement. Interestingly, the low inferred bias between LS3D and DXA using existing data suggests that LS3D may have high agreement with dual-energy x-ray absorptiometry. Overall, the suitability of LS2D and LS3D to replace conventional methods must be based on an individual user's criteria.

Remote Patient Monitoring for the Detection of COPD Exacerbations.

Background: COPD exacerbations occur more frequently with disease progression and are associated with worse prognosis and higher healthcare expenditure. Purpose: To utilize a networked system, optimized with statistical process control (SPC), for remote patient monitoring (RPM) and to identify potential predictors of COPD exacerbations. Methods: Seventeen subjects, mean (SD) age of 69.7 (7.2) years, with moderate to severe COPD received RPM. Over 2618 patient-days (7.17 patient-years) of monitoring, we obtained daily symptom scores, treatment adherence, self-reported activity levels, daily spirometry (SVC, FEV1, FVC, PEF), inspiratory capacity (IC), and oxygenation (SpO2). These data were used to identify predictors of exacerbations defined using Anthonisen and other criteria. Results: After implementation of SPC, concordance analysis showed substantial agreement between FVC (decrease below the 7-day rolling average minus 1.645 SD) and self-reported healthcare utilization events (κ=0.747, P<0.001) as well as between increased use of inhaled short-acting bronchodilators and exacerbations defined by two Anthonisen criteria (κ=0.611, P<0.001) or modified Anthonisen criteria (κ=0.622, P<0.001). There was a moderate agreement between FEV1 (decrease >1.645 SD below the 7-day rolling average) and self-reported healthcare utilization events (κ=0.475, P<0.001) and between SpO2 less than 90% and exacerbations defined by two Anthonisen criteria (κ=0.474, P<0.001) or modified Anthonisen criteria (κ=0.564, P<0.001). Conclusion: Exacerbations were best predicted by FVC and FEV1 below the one-sided 95% confidence interval derived from SPC but also by increased use of inhaled short-acting bronchodilators and fall in oxygen saturation. An RPM program that captures these parameters may be used to guide appropriate interventions aimed at reducing healthcare utilization in COPD patients.

Not All HIFT Classes Are Created Equal: Evaluating Energy Expenditure and Relative Intensity of a High-Intensity Functional Training Regimen.

The demand for efficient and effective exercises has grown in concert with increased attention to fitness as a determinant of overall health. While past studies have examined the benefits traditional conditioning exercises, there have been few investigations of high intensity functional training (HIFT). The aim of this study was to measure the energy expenditure and relative intensity from participation in a signature, 35-minute group-based HIFT regimen. During the HIFT session, 13 volunteers (aged 23-59 years, 6 females) donned a portable breath-by-breath gas analyzer and a heart rate monitor. Mean caloric expenditure (528 ± 62 kcal), maximum heart rate (172 ± 8 bpm), and metabolic equivalents (12.2 ± 1.4 kcal/kg/h) were characterized as a vigorous-intensity activity according to the Compendium of Physical Activities guidelines. Moreover, implementing this high energy expenditure session twice weekly may comport with Physical Activity Guidelines for Americans weekly physical activity recommendations. HIFT training may provide time-efficient exercise for those seeking exercise-related health benefits.

Donning a Novel Lower-Limb Restrictive Compression Garment During Training Augments Muscle Power and Strength.

The popularity of graduated compression garments (GCG) in sport and exercise is largely driven by the abundance of anecdotal claims suggesting their efficacy. A new line of compression apparel, restrictive compression garments (RCG), integrate novel resistance technology into lower-limb compression garments designed to provide variable resistance to movement. This study aimed to investigate the effect of donning an RCG during a 4-week training program on selected performance variables. Twelve college-aged males were recruited for four weeks of lower-body strength-power resistance training. Participants were randomized 1:1 and blinded to (i) an intervention group (RCG; n = 6) that donned a lower-body RCG during training or (ii) a control group (SHAM; n = 6) that donned a sham during identical training. Both groups demonstrated significant increases in 1-repetition maximum (1-RM) on a seated leg press after 4 weeks (both p < 0.001), with RCG showing a significantly greater increase compared SHAM (p = 0.005, g = 3.35). Similarly, RCG demonstrated significantly greater increases in jump height, peak power, and average power compared to SHAM (p = 0.032, g = 3.44; p < 0.001, g = 4.40; p < 0.001, g = 4.50, respectively). Donning a RCG while engaging in lower-body strength-power training may augment increases 1-RM on a seated leg press, jump height, peak and average power, compared with same exercise training without an RCG.

Reference Values for Chronotropic Index from 1280 Incremental Cycle Ergometry Tests.

PURPOSE: Clinical cardiopulmonary exercise testing can determine causes of exercise limitation. The slope of heart rate (fC) versus oxygen uptake (V˙O2), which we call the chronotropic index (CI), can help identify cardiovascular impairment. We aimed to develop a reference equation for CI based on a large number of subjects considered to have normal exercise responses. METHODS: From a database of 13,728 incremental cycle ergometry exercise tests, we identified 1280 normal tests based on the absence of a clinical diagnosis, normal body mass index, and normal aerobic performance plus absence of cardiovascular disease, medications, or ventilatory limitation. A linear mixed-model approach was used to analyze the relationship between CI and other variables. RESULTS: Subjects were age 18-84 yr, and 693 (54.1%) were men. Mean ± SD CI in men was lower than in women, 41.2 ± 9.3 beats per liter versus 63.4 ± 15.7 L. Age (in years), sex (0, male; 1, female), height (in centimeters), and weight (in kilograms) were significant predictors for CI:CIi = 106.9 + 0.16 × agei + 14.3 × sexi - 0.31 × heighti - 0.24 × weighti. The SE of estimates ranged from 10.6 to 11.2 L (median of 10.7 L). CONCLUSIONS: We report a reference equation for CI derived from normal subjects. The CI can be used in conjunction with V˙O2max to interpret maximal cardiopulmonary exercise tests. We consider a high CI to be cardiovascular impairment and a low CI plus low V˙O2max to be chronotropic insufficiency.

The Cumulative Effect of Substance Abuse Disorders and Depression on Postoperative Complications After Primary Total Knee Arthroplasty.

BACKGROUND: Substance abuse disorder (SUD), alcohol abuse disorder (AUD), and depression have been identified as independent risk factors for complications after total knee arthroplasty (TKA). However, these mental health disorders are highly co-associated, and their cumulative effect on postoperative complications have not been investigated. Therefore, this study aimed to determine if patients who have more than one mental health disorder (SUD, AUD, or depression) were at an increased risk for postoperative complications following TKA. METHODS: A total of 11,403 TKA patients were identified from a prospectively collected institutional database between January 1, 2017 and April 1, 2019. Patients who had depression, SUD, and AUD were separated into 7 mental health subgroups including each of these diagnoses alone and their combined permeations. Patient demographics, body mass indices, medical comorbidities, and 15 postoperative complications were collected. Univariate analyses were performed using independent Student's t-tests. Multivariate analyses were then performed to identify odds ratios (ORs) for mental health disorders subgroups associated with complications. RESULTS: We found a total of 2073 (18%) patients diagnosed with either SUD (4%), AUD (0.6%), or depression (12%). Univariate analyses showed that depression was associated with mechanical failures (P < .001). SUD was associated with periprosthetic joint infection (PJI) (P < .001), wound complications (P = .022), and aseptic loosening (P = .007). AUD was associated with PJI (P < .001) and deep vein thromboses (P = .003). Multivariate analyses found that AUD (OR: 19.419, P < .001) and SUD (OR:3.693, P = .010) were independent risk factors for PJI. Compared with SUD alone, patients with depression plus SUD were found to have a 4-fold (OR: 13.639, P < .001) and 2-fold (OR:4.401, P = .021) increased risk for PJI and cellulitis, respectively. CONCLUSIONS: Patients who had depression, SUD, or AUD were at increased risk for postoperative complications following primary TKA. When patients have more than one mental health diagnosis, their risk for complications was amplified. The results of this study can help identify those patients who are at greater risk of postoperative complications to enable improved preoperative optimization and patient education.