Agreement between arterial and end-tidal carbon dioxide in adult patients admitted with serious traumatic brain injury.

BACKGROUND: Low-normal levels of arterial carbon dioxide (PaCO2) are recommended in the acute phase of traumatic brain injury (TBI) to optimize oxygen and CO2 tension, and to maintain cerebral perfusion. End-tidal CO2 (ETCO2) may be used as a surrogate for PaCO2 when arterial sampling is less readily available. ETCO2 may not be an adequate proxy to guide ventilation and the effects on concomitant injury, time, and the impact of ventilatory strategies on the PaCO2-ETCO2 gradient are not well understood. The primary objective of this study was to describe the correlation and agreement between PaCO2 and ETCO2 in intubated adult trauma patients with TBI. METHODS: This study was a retrospective analysis of prospectively-collected data of intubated adult major trauma patients with serious TBI, admitted to the East of England regional major trauma centre; 2015-2019. Linear regression and Welch's test were performed on each cohort to assess correlation between paired PaCO2 and ETCO2 at 24-hour epochs for 120 hours after admission. Bland-Altman plots were constructed at 24-hour epochs to assess the PaCO2-ETCO2 agreement. RESULTS: 695 patients were included, with 3812 paired PaCO2 and ETCO2 data points. The median PaCO2-ETCO2 gradient on admission was 0.8 [0.4-1.4] kPa, Bland Altman Bias of 0.96, upper (+2.93) and lower (-1.00), and correlation R2 0.149. The gradient was significantly greater in patients with TBI plus concomitant injury, compared to those with isolated TBI (0.9 [0.4-1.5] kPa vs. 0.7 [0.3-1.1] kPa, p<0.05). Across all groups the gradient reduced over time. Patients who died within 30 days had a larger gradient on admission compared to those who survived; 1.2 [0.7-1.9] kPa and 0.7 [0.3-1.2] kPa, p<0.005. CONCLUSIONS: Amongst adult patients with TBI, the PaCO2-ETCO2 gradient was greater than previously reported values, particularly early in the patient journey, and when associated with concomitant chest injury. An increased PaCO2-ETCO2 gradient on admission was associated with increased mortality.

Utilizing generative conversational artificial intelligence to create simulated patient encounters: a pilot study for anaesthesia training.

PURPOSE OF THE STUDY: Generative conversational artificial intelligence (AI) has huge potential to improve medical education. This pilot study evaluated the possibility of using a 'no-code' generative AI solution to create 2D and 3D virtual avatars, that trainee doctors can interact with to simulate patient encounters. METHODS: The platform 'Convai' was used to create a virtual patient avatar, with a custom backstory, to test the feasibility of this technique. The virtual patient model was set up to allow trainee anaesthetists to practice answering questions that patients' may have about interscalene nerve blocks for open reduction and internal fixation surgery. This tool was provided to anaesthetists to receive their feedback and evaluate the feasibility of this approach. RESULTS: Fifteen anaesthetists were surveyed after using the tool. The tool had a median score [interquartile range (IQR)] of 9 [7-10] in terms of how intuitive and user-friendly it was, and 8 [7-10] in terms of accuracy in simulating patient responses and behaviour. Eighty-seven percent of respondents felt comfortable using the model. CONCLUSIONS: By providing trainees with realistic scenarios, this technology allows trainees to practice answering patient questions regardless of actor availability, and indeed from home. Furthermore, the use of a 'no-code' platform allows clinicians to create customized training tools tailored to their medical specialties. While overall successful, this pilot study highlighted some of the current drawbacks and limitations of generative conversational AI, including the risk of outputting false information. Additional research and fine-tuning are required before generative conversational AI tools can act as a substitute for actors and peers.

Ultrasonographic visualization of anatomical variations of the supraclavicular nerves.

Typical anatomy of the supraclavicular nerve (SCN) is described as originating from the cervical plexus and dividing into medial, intermediate, and lateral branches. The SCN is vulnerable to injury during clavicular surgery, leading to altered sensation post-operatively. There is also increasing interest in anesthetizing the SCN in shoulder or clavicular surgery. Utilizing a high-frequency (20 MHz) ultrasound probe, 20 healthy volunteers were scanned, giving data for 40 SCNs. For each nerve, anatomical course and branches were graphically plotted using a custom Python 3.8.12 program and Microsoft Excel. Of 40 nerves, only 19 (47.5%) demonstrated a typical course, with the rest showing considerable variability of branching patterns. Crossing branches (CBs) were found in 24 (60%) with a total of 54. Just over half (29, 54.7%) of these crossed the clavicle lateral to its midpoint, with 32 (59.6%) CBs having a diameter of ≥25% compared to that of the SCN main trunk. The distance from the mid-clavicular point at which the branches crossed the clavicle was recorded. This study demonstrated that over half the SCNs had atypical branching patterns with intra-volunteer variability. Preoperative mapping may be useful in preventing injury and subsequent numbness.

Polytraumatized patient lower extremity nonunion development: Raw data.

In this article we report data collected to evaluate the pathomechanistic effect of acute anaerobic metabolism in the polytraumatized patient and its subsequent effect on fracture nonunion; see "Base Deficit ≥6 within 24 Hours of Injury is a Risk Factor for Fracture Nonunion in the Polytraumatized Patient" (Sardesai et al., 2021) [1]. Data was collected on patients age ≥16 with an Injury Severity Score (ISS) >16 that presented between 2013-2018 who sustained a fracture of the tibia or femur distal to the femoral neck. Patients presenting to our institution greater than 24 hours post-injury and those with less than three months follow-up were excluded. Medical charts were reviewed to collect patient demographic information and known nonunion risk-factors, including smoking, alcohol use, and diabetes. In addition, detailed injury characteristics to quantify injury magnitude including ISS, Glasgow Coma Scale (GCS) at admission, and ICU length of stay were recorded. ISS values were obtained from our institutional trauma database where they are entered by individuals trained in ISS calculations. Associated fracture-related features including fracture location, soft-tissue injury (open vs. closed fracture), vascular injury, and compartment syndrome were recorded. Finally, vital signs, base deficit (BD), and blood transfusions over 24 hours from admission were recorded. We routinely measure BD and less consistently measure serum lactate in trauma patients at the time of presentation or during resuscitation. BD values are automatically produced by our laboratory with any arterial blood gas order, and we recorded BD values from the medical record. Clinical notes and radiographs were reviewed to confirm fracture union versus nonunion and assess for deep infection at the fracture site. Patients were categorized as having a deep infection if they were treated operatively for the infection prior to fracture healing or classification as a nonunion. Nonunion was defined by failure of progressive healing on sequential radiographs and/or surgical treatment for nonunion repair at least six months post-injury.

Base Deficit ≥ 6 within 24 h of Injury is a risk factor for fracture nonunion in the polytraumatized patient.

BACKGROUND: Polytrauma patients are at risk for fracture nonunion, but the reasons are poorly understood. Increased base deficit (BD) is associated with hypovolemic shock. Although shock delays bone healing in animal models, there have been no clinical studies evaluating the impact of BD on nonunion risk. MATERIALS AND METHODS: Patients age ≥ 16 with injury severity score > 16 that presented to an academic Level One trauma center with an operative femur or tibia fracture were reviewed. Clinical notes and radiographs were assessed to determine fracture healing status. Patient demographics, injury characteristics, BD, and number of packed red blood cell transfusions were recorded. Bivariate and multivariate analyses of multiple risk factors associated with nonunion were conducted to investigate the association of BD with nonunion. RESULTS: The union group was comprised of 243 fractures; there were 36 fractures in the nonunion group. The following predictors were associated with nonunion: smoking (p = 0.009), alcohol use (p < 0.001), open fracture (p < 0.001), and treatment for deep infection at fracture site (p = 0.016). Additionally, worst BD over 24 h ≥ 6 (p = 0.031) was significant for nonunion development. A multivariate logistic regression analysis revealed worst BD ≥6 over 24 h remained significantly associated with the development of nonunion (odds ratio 3.02, p = 0.011) when adjusting for other risk factors. CONCLUSIONS: A BD ≥ 6 within 24 h of admission was associated with a significantly increased risk of developing lower extremity fracture nonunion in polytrauma patients, even after adjusting for multiple other risk factors. Acute post-traumatic acidosis may have effects on long-term fracture healing.

Acute total hip arthroplasty for older patients with acetabular fractures: A meta-analysis.

OBJECTIVE: Multiple treatment options for acetabular fractures in geriatric patients exist. However, no large-scale studies have reported the outcomes of acute total hip arthroplasty (THA) in this patient population. We systematically evaluated all available evidence to characterize clinical outcomes, complications, and revisions of acute THA for acetabular fractures in geriatric patients. METHODS: Meta-analysis of 21 studies of 430 acetabular fractures with mean follow-up of 44 months (range, 17-97 months). Two independent researchers searched and evaluated the databases of Ovid, Embase, and United States National Library of Medicine using a Boolean search string up to December 2019. Population demographics and complications, including presence of heterotopic ossification (HO), dislocation, infection, revision rate, neurological deficits, and venous thromboembolic event (VTE), were recorded and analyzed. RESULTS: Weighted mean Harris Hip Score was 83.3 points, and 20% of the patients had reported complications. The most common complication was HO, with a rate of 19.5%. Brooker grade III and IV HO rates were lower at 6.8%. Hip dislocation occurred at a rate of 6.1%, 4.1% of patients developed VTE, deep infection occurred in 3.8%, and neurological complications occurred in 1.9%. Although the revision rate was described in most studies, we were unable to perform a survival analysis because the time to each revision was described in only a few studies. The revision rate was 4.3%. CONCLUSIONS: Acute THA is a viable option for treatment of acetabular fracture and can result in acceptable clinical outcomes and survivorship rates in older patients but with an associated complication rate of approximately 20%. Considering the limited treatment options, THA might be a viable alternative for appropriately selected patients.

Effect of Surgical Setting on Hospital-Reported Outcomes for Elective Lumbar Spinal Procedures: Tertiary Versus Community Hospitals.

STUDY DESIGN: Retrospective cohort study. OBJECTIVE: As hospital compensation becomes increasingly dependent on pay-for-performance and bundled payment compensation models, hospitals seek to reduce costs and increase quality. To our knowledge, no reported data compare these measures between hospital settings for elective lumbar procedures. The study compares hospital-reported outcomes and costs for elective lumbar procedures performed at a tertiary hospital (TH) versus community hospitals (CH) within a single health care system. METHODS: Retrospective review of a physician-maintained, prospectively collected database consisting of 1 TH and 4 CH for 3 common lumbar surgeries from 2015 to 2016. Patients undergoing primary elective microdiscectomy for disc herniation, laminectomy for spinal stenosis, and laminectomy with fusion for degenerative spondylolisthesis were included. Patients were excluded for traumatic, infectious, or malignant pathology. Comparing hospital settings, outcomes included length of stay (LOS), rates of 30-day readmissions, potentially preventable complications (PPC), and discharge to rehabilitation facility, and hospital costs. RESULTS: A total of 892 patients (n = 217 microdiscectomies, n = 302 laminectomies, and n = 373 laminectomy fusions) were included. The TH served a younger patient population with fewer comorbid conditions and a higher proportion of African Americans. The TH performed more decompressions (P < .001) per level fused; the CH performed more interbody fusions (P = .007). Cost of performing microdiscectomy (P < .001) and laminectomy (P = .014) was significantly higher at the TH, but there was no significant difference for laminectomy with fusion. In a multivariable stepwise linear regression analysis, the TH was significantly more expensive for single-level microdiscectomy (P < .001) and laminectomy with single-level fusion (P < .001), but trended toward significance for laminectomy without fusion (P = .052). No difference existed for PPC or readmissions rate. Patients undergoing laminectomy without fusion were discharged to a facility more often at the TH (P = .019). CONCLUSIONS: We provide hospital-reported outcomes between a TH and CH. Significant differences in patient characteristics and surgical practices exist between surgical settings. Despite minimal differences in hospital-reported outcomes, the TH was significantly more expensive.

Unicompartmental knee arthroplasty for spontaneous osteonecrosis of the knee: A meta-analysis.

BACKGROUND: Spontaneous osteonecrosis of the knee (SONK) is a poorly understood but debilitating disease entity. Total knee arthroplasty (TKA) is the standard of care for those patients who fail conservative management, but considering SONK's predilection for affecting a single knee compartment, unicompartmental knee arthroplasty (UKA) appears to be a more tailored option. Unfortunately, conflicting data exist on the utility of UKA in SONK. Thus, the purpose of this study was to evaluate functional outcomes and revision rates of UKA in the setting of SONK. METHODS: A systematic literature search was performed to evaluate all studies examining patients who underwent UKA for SONK. Screening of the articles was performed using multiple Boolean search strings, methodological index for non-randomized studies criteria, and other selected exclusion criteria. RESULTS: Seven studies were included, with a total of 276 knees (273 patients). The mean age was 68 years (64-74 years), with a mean body mass index of 26 kg/m2 (25-29 kg/m2). The final range of motion was 125° (124-126°). Standardized mean difference (SMD) of clinical improvement pre- and post-outcome was 3.39 ( p < 0.001). The improvement in the visual analog score was 57.03 points, with an SMD of 4.57 ( p < 0.001). Revision rates were determined to be 5.51% (95% confidence interval of 1.96-10.69%). CONCLUSION: Our meta-analysis demonstrated that in properly selected patients, UKA could be an excellent alternative to TKA for patients with SONK. These data show that UKA has few complications, significant improvements on functional outcomes, and good survivorship at a mean follow-up of 6 years.

Operative management of acetabulum fractures in the obese patient: challenges and solutions.

In this review, we aim to increase our knowledge of the treatment of acetabular fractures in the obese patient population. The extremely high incidence of obesity in the USA is a looming health care concern that impacts aspects of health care in all medical specialties. There are specific concerns to the orthopedic surgeon when treating obese patients for acetabular fracture. Patients with body mass index ≥30 present particular challenges to the surgeon in terms of preexisting medical conditions, diagnostic imaging, and perioperative complications. Specifically, this patient population experiences worse functional outcomes and greater incidence of surgical site infection, intraoperative blood loss, deep venous thrombosis, post-traumatic osteoarthritis, heterotopic ossification, and increased hospital length of stay. These problems are further exacerbated in the morbidly obese, as a scaling effect exists between increasing body mass index and worsening complication profile. This is problematic given the current high incidence of morbid obesity in the USA and particularly worrisome in light of the projected increase in obesity rates for the future.