Surgery in the Era of Immunotherapy for Advanced Head and Neck Non-melanoma Skin Cancer.

PURPOSE OF REVIEW: Surgery remains the mainstay of treatment for non-melanoma skin cancer (NMSC). Immunotherapy (IO) has emerged as an alternative option. This review provides a contemporary summary of how to incorporate IO into the management of advanced NMSC. Evidence-based outcomes and recent clinical trials are provided with emphasis on the three most common NMSC diagnoses: cutaneous squamous cell carcinoma (cSCC), basal cell carcinoma (BCC), and merkel cell carcinoma (MCC). RECENT FINDINGS: Surgical resection while preserving form and function remains the standard of care for the majority of NMSCs. In recalcitrant cases failing traditional surgery and/or primary radiation, patient ineligible for such treatments, or unresectable disease, IO has emerged as a promising alternative. In the majority of cases, it is a supplanting primary chemotherapy. Surgery remains the standard of care for NMSC. Immunotherapy has emerged as an alternative option for non-surgical candidates and as a neoadjuvant means to minimize morbidity.

Co-opting regulation bypass repair as a gene-correction strategy for monogenic diseases.

With the development of CRISPR-Cas9-mediated gene-editing technologies, correction of disease-causing mutations has become possible. However, current gene-correction strategies preclude mutation repair in post-mitotic cells of human tissues, and a unique repair strategy must be designed and tested for each and every mutation that may occur in a gene. We have developed a novel gene-correction strategy, co-opting regulation bypass repair (CRBR), which can repair a spectrum of mutations in mitotic or post-mitotic cells and tissues. CRBR utilizes the non-homologous end joining (NHEJ) pathway to insert a coding sequence (CDS) and transcription/translation terminators targeted upstream of any CDS mutation and downstream of the transcriptional promoter. CRBR results in simultaneous co-option of the endogenous regulatory region and bypass of the genetic defect. We validated the CRBR strategy for human gene therapy by rescuing a mouse model of Wolcott-Rallison syndrome (WRS) with permanent neonatal diabetes caused by either a large deletion or a nonsense mutation in the PERK (EIF2AK3) gene. Additionally, we integrated a CRBR GFP-terminator cassette downstream of the human insulin promoter in cadaver pancreatic islets of Langerhans, which resulted in insulin promoter regulated expression of GFP, demonstrating the potential utility of CRBR in human tissue gene repair.

Cross Talk Inhibition Nullified by a Receiver Domain Missense Substitution.

UNLABELLED: In two-component signal transduction, a sensor protein transmitter module controls cognate receiver domain phosphorylation. Most receiver domain sequences contain a small residue (Gly or Ala) at position T + 1 just distal to the essential Thr or Ser residue that forms part of the active site. However, some members of the NarL receiver subfamily have a large hydrophobic residue at position T + 1. Our laboratory previously isolated a NarL mutant in which the T + 1 residue Val-88 was replaced with an orthodox small Ala. This NarL V88A mutant confers a striking phenotype in which high-level target operon expression is both signal (nitrate) and sensor (NarX and NarQ) independent. This suggests that the NarL V88A protein is phosphorylated by cross talk from noncognate sources. Although cross talk was enhanced in ackA null strains that accumulate acetyl phosphate, it persisted in pta ackA double null strains that cannot synthesize this compound and was observed also in narL(+) strains. This indicates that acetate metabolism has complex roles in mediating NarL cross talk. Contrariwise, cross talk was sharply diminished in an arcB barA double null strain, suggesting that the encoded sensors contribute substantially to NarL V88A cross talk. Separately, the V88A substitution altered the in vitro rates of NarL autodephosphorylation and transmitter-stimulated dephosphorylation and decreased affinity for the cognate sensor, NarX. Together, these experiments show that the residue at position T + 1 can strongly influence two distinct aspects of receiver domain function, the autodephosphorylation rate and cross talk inhibition. IMPORTANCE: Many bacterial species contain a dozen or more discrete sensor-response regulator two-component systems that convert a specific input into a distinct output pattern. Cross talk, the unwanted transfer of signals between circuits, occurs when a response regulator is phosphorylated inappropriately from a noncognate source. Cross talk is inhibited in part by the high interaction specificity between cognate sensor-response regulator pairs. This study shows that a relatively subtle missense change from Val to Ala nullifies cross talk inhibition, enabling at least two noncognate sensors to enforce an inappropriate output independently of the relevant input.

Cofilin under control of ß-arrestin-2 in NMDA-dependent dendritic spine plasticity, long-term depression (LTD), and learning.

Dendritic spines are dynamic, actin-rich structures that form the postsynaptic sites of most excitatory synapses in the brain. The F-actin severing protein cofilin has been implicated in the remodeling of dendritic spines and synapses under normal and pathological conditions, by yet unknown mechanisms. Here we report that ß-arrestin-2 plays an important role in NMDA-induced remodeling of dendritic spines and synapses via translocation of active cofilin to dendritic spines. NMDAR activation triggers cofilin activation through calcineurin and phosphatidylinositol 3-kinase (PI3K)-mediated dephosphorylation and promotes cofilin translocation to dendritic spines that is mediated by ß-arrestin-2. Hippocampal neurons lacking ß-arrestin-2 develop mature spines that fail to remodel in response to NMDA. ß-Arrestin-2-deficient mice exhibit normal hippocampal long-term potentiation, but significantly impaired NMDA-dependent long-term depression and spatial learning deficits. Moreover, ß-arrestin-2-deficient hippocampal neurons are resistant to Aß-induced dendritic spine loss. Our studies demonstrate unique functions of ß-arrestin-2 in NMDAR-mediated dendritic spine and synapse plasticity through spatial control over cofilin activation.

Hunter-gatherer genomic diversity suggests a southern African origin for modern humans.

Africa is inferred to be the continent of origin for all modern human populations, but the details of human prehistory and evolution in Africa remain largely obscure owing to the complex histories of hundreds of distinct populations. We present data for more than 580,000 SNPs for several hunter-gatherer populations: the Hadza and Sandawe of Tanzania, and the ≠Khomani Bushmen of South Africa, including speakers of the nearly extinct N|u language. We find that African hunter-gatherer populations today remain highly differentiated, encompassing major components of variation that are not found in other African populations. Hunter-gatherer populations also tend to have the lowest levels of genome-wide linkage disequilibrium among 27 African populations. We analyzed geographic patterns of linkage disequilibrium and population differentiation, as measured by F(ST), in Africa. The observed patterns are consistent with an origin of modern humans in southern Africa rather than eastern Africa, as is generally assumed. Additionally, genetic variation in African hunter-gatherer populations has been significantly affected by interaction with farmers and herders over the past 5,000 y, through both severe population bottlenecks and sex-biased migration. However, African hunter-gatherer populations continue to maintain the highest levels of genetic diversity in the world.

Developmental and physiological impacts of pathogenic human huntingtin protein in the nervous system.

Huntington's Disease (HD) is a neurodegenerative disorder, part of the nine identified inherited polyglutamine (polyQ) diseases. Most commonly, HD pathophysiology manifests in middle-aged adults with symptoms including progressive loss of motor control, cognitive decline, and psychiatric disturbances. Associated with the pathophysiology of HD is the formation of insoluble fragments of the huntingtin protein (htt) that tend to aggregate in the nucleus and cytoplasm of neurons. To track both the intracellular progression of the aggregation phenotype as well as the physiological deficits associated with mutant htt, two constructs of human HTT were expressed with varying polyQ lengths, non-pathogenic-htt (Q15, NP-htt) and pathogenic-htt (Q138, P-htt), with an N-terminal RFP tag for in vivo visualization. P-htt aggregates accumulate in the ventral nerve cord cell bodies as early as 24 hours post hatching and significant aggregates form in the segmental nerve branches at 48 hours post hatching. Organelle trafficking up-and downstream of aggregates formed in motor neurons showed severe deficits in trafficking dynamics. To explore putative downstream deficits of htt aggregation, ultrastructural changes of presynaptic motor neurons and muscles were assessed, but no significant effects were observed. However, the force and kinetics of muscle contractions were severely affected in P-htt animals, reminiscent of human chorea. Reduced muscle force production translated to altered locomotory behavior. A novel HD aggregation model was established to track htt aggregation throughout adulthood in the wing, showing similar aggregation patterns with larvae. Expressing P-htt in the adult nervous system resulted in significantly reduced lifespan, which could be partially rescued by feeding flies the mTOR inhibitor rapamycin. These findings advance our understanding of htt aggregate progression as well the downstream physiological impacts on the nervous system and peripheral tissues.

Flap outcomes when training residents in microvascular anastomosis in the head and neck.

OBJECTIVE: Microvascular anastomosis is generally performed by attending surgeons or fellows, with published success rates >95%. Since otolaryngology residents do not typically perform microvascular anastomosis, it is unknown if they achieve similar results. The objective of this study is to determine the success rate and complication rate during free flap reconstruction when microvascular anastomosis is performed in part by otolaryngology chief residents. STUDY DESIGN: Multi-institutional retrospective review. SETTING: Academic, tertiary-care referral centers. SUBJECTS AND METHODS: Consecutive patients who underwent microvascular reconstruction by the Department of Otolaryngology from 2004 through 2011. All patients had >50% of the arterial and venous anastomoses performed by the chief resident. RESULTS: The study included 93 consecutive free flaps in 88 patients: 43 radial forearm, 14 anterolateral thigh, and 36 fibula. There were 71 males and 22 females with mean age of 53. The pre-operative diagnosis was squamous cell carcinoma in 78%, with 27% of patients having previously received radiotherapy and 13% of patients having had previous neck surgery. There were no instances when resident-placed sutures required revision, nor was there a perceived need to revise such an anastomosis intraoperatively. Overall flap success rate was 97%. The anastomotic complication rate was 4.3%, with venous thrombosis in three cases and arterial hemorrhage in one case. CONCLUSION: Overall free flap success rate and anastomosis-related complications with residents performing portions of the microvascular anastomosis are comparable to published studies. Otolaryngology chief residents can safely participate in microsuturing, which is a single facet in the broader skill set of a microvascular surgeon.

Scalp and Calvarium Reconstruction.

Defects of the scalp and calvarium pose unique reconstructive challenges due to the importance of this area in protecting the brain and its distance from larger donor vessels for free flap transfer. The wide range and complexity of reconstructive options make this a broad topic because the simplest defects are often closed or managed in the outpatient setting and the most complex require multilayer closure in the operating room with a multidisciplinary team and intensive postoperative care. In hair-bearing individuals, the scalp is an esthetically important area due to the importance of hair to self-esteem and sexual attraction.

Novel Generative Recurrent Neural Network Framework to Produce Accurate, Applicable, and Deidentified Synthetic Medical Data for Patients With Metastatic Cancer.

PURPOSE: Sensitive patient data cannot be easily shared/analyzed, severely limiting the innovative progress of research, specifically for marginalized/under-represented populations. Existing methods of deidentification are subject to data breaches. The objective of this study was to develop a neural network capable of generating a synthetic version of data for patients with novel postoperative metastatic cancer. METHODS: We analyzed a metastatic cancer patient cohort of 167,474 patients obtained from the National Surgical Quality Improvement Program. Twenty-seven clinical features were analyzed. We created a volume-matched synthetic cohort of 167,474 patients and a reduced-size synthetic cohort of 5,000 patients. The volume-matched and reduced-size synthetic cohorts were compared against the ground truth data to analyze differences in principal component distribution, underlying statistical properties/associations, intervariable correlations, and machine learning classifier performance when developed on the synthetic data. RESULTS: Among 167,474 patients with metastatic cancer in the original data, 50,669 (30.3%) died within 30 days of their index surgery. Our model was able to accurately capture underlying statistical properties, principal components, and intervariable correlations within the ground truth data, yielding an accuracy of 93.2% with a loss of 0.21%, and develop synthetic data capable of training accurate machine learning classifiers. The reduced-size synthetic data accurately replicated all categorical variables and every continuous variable with statistically similar records (P > .05), with the sole exception of preoperative albumin (P < .05). The volume-matched synthetic data frame was able to accurately replicate all categorical variables (P > .05). CONCLUSION: This described methodology can be applied to any structured medical data from any setting, significantly expedite scientific analysis/innovation, and be used to develop improved predictive classifiers with boosted tree-based algorithms, serving as the potential new gold standard of medical data sharing and data augmentation.

Activity-dependent ectopic action potentials in regular-spiking neurons of the neocortex.

Introduction: Action potentials usually travel orthodromically along a neuron's axon, from the axon initial segment (AIS) toward the presynaptic terminals. Under some circumstances action potentials also travel in the opposite direction, antidromically, after being initiated at a distal location. Given their initiation at an atypical site, we refer to these events as "ectopic action potentials." Ectopic action potentials (EAPs) were initially observed in pathological conditions including seizures and nerve injury. Several studies have described regular-spiking (RS) pyramidal neurons firing EAPs in seizure models. Under nonpathological conditions, EAPs were reported in a few populations of neurons, and our group has found that EAPs can be induced in a large proportion of parvalbumin-expressing interneurons in the neocortex. Nevertheless, to our knowledge there have been no prior reports of ectopic firing in the largest population of neurons in the neocortex, pyramidal neurons, under nonpathological conditions. Methods: We performed in vitro recordings utilizing the whole-cell patch clamp technique. To elicit EAPs, we triggered orthodromic action potentialswith either long, progressively increasing current steps, or with trains of brief pulses at 30, 60, or 100 Hz delivered in 3 different ways, varying in stimulus and resting period duration. Results: We found that a large proportion (72.7%) of neocortical RS cells from mice can fire EAPs after a specific stimulus in vitro, and that most RS cells (56.1%) are capable of firing EAPs across a broad range of stimulus conditions. Of the 37 RS neurons in which we were able to elicit EAPs, it took an average of 863.8 orthodromic action potentials delivered over the course of an average of ~81.4 s before the first EAP was seen. We observed that some cells responded to specific stimulus frequencies while less selective, suggesting frequency tuning in a subset of the cells. Discussion: Our findings suggest that pyramidal cells can integrate information over long time-scales before briefly entering a mode of self-generated firing that originates in distal axons. The surprising ubiquity of EAP generation in RS cells raises interesting questions about the potential roles of ectopic spiking in information processing, cortical oscillations, and seizure susceptibility.

American Head and Neck Society position statement on the use of PD-1 inhibitors for treatment of advanced cutaneous squamous cell carcinoma.

BACKGROUND: A position statement put forth by the American Head and Neck Society (AHNS) was constructed to provide evidence-based treatment recommendations for PD-1 inhibitor use in advanced cutaneous squamous cell carcinoma (cSCC). Secondarily, we sought to identify knowledge gaps warranting further investigation. METHODS: A literature search utilizing key terms: cutaneous squamous cell carcinoma, cutaneous cancer, checkpoint inhibitors, systemic therapy, Program Cell Death, PD-1 (PubMed, Cochrane, and Google Scholar) was carried out to generate evidence-based statements. The statements were distributed among the AHNS membership. Delphi methodology was applied to identify statements achieving 70% or greater consensus among the leadership team. RESULTS: Twenty-six position statements achieved consensus. Knowledge gaps for future research included: impact of immunosuppression on cSCC staging and associated treatment; role of PD-1 inhibitors in immunosuppressed patients. CONCLUSION: This comprehensive position statement put forth by the AHNS represents majority consensus by practicing head and neck surgeons throughout the country.

Tracheostomies of Patients With COVID-19: A Survey of Infection Reported by Health Care Professionals.

BACKGROUND: Health care professionals (HCPs) performing tracheostomies in patients with COVID-19 may be at increased risk of infection. OBJECTIVE: To evaluate factors underlying HCPs' COVID-19 infection and determine whether tracheostomy providers report increased rates of infection. METHODS: An anonymous international survey examining factors associated with COVID-19 infection was made available November 2020 through July 2021 to HCPs at a convenience sample of hospitals, universities, and professional organizations. Infections reported were compared between HCPs involved in tracheostomy on patients with COVID-19 and HCPs who were not involved. RESULTS: Of the 361 respondents (from 33 countries), 50% (n = 179) had performed tracheostomies on patients with COVID-19. Performing tracheostomies on patients with COVID-19 was not associated with increased infection in either univariable (P = .06) or multivariable analysis (odds ratio, 1.48; 95% CI, 0.90-2.46; P = .13). Working in a low- or middle-income country (LMIC) was associated with increased infection in both univariable (P < .001) and multivariable analysis (odds ratio, 2.88; CI, 1.50-5.53; P = .001). CONCLUSIONS: Performing tracheostomy was not associated with COVID-19 infection, suggesting that tracheostomies can be safely performed in infected patients with appropriate precautions. However, HCPs in LMICs may face increased infection risk.

AZD5582 plus SIV-specific antibodies reduce lymph node viral reservoirs in antiretroviral therapy-suppressed macaques.

The main barrier to HIV cure is a persistent reservoir of latently infected CD4+ T cells harboring replication-competent provirus that fuels rebound viremia upon antiretroviral therapy (ART) interruption. A leading approach to target this reservoir involves agents that reactivate latent HIV proviruses followed by direct clearance of cells expressing induced viral antigens by immune effector cells and immunotherapeutics. We previously showed that AZD5582, an antagonist of inhibitor of apoptosis proteins and mimetic of the second mitochondrial-derived activator of caspases (IAPi/SMACm), induces systemic reversal of HIV/SIV latency but with no reduction in size of the viral reservoir. In this study, we investigated the effects of AZD5582 in combination with four SIV Env-specific Rhesus monoclonal antibodies (RhmAbs) ± N-803 (an IL-15 superagonist) in SIV-infected, ART-suppressed rhesus macaques. Here we confirm the efficacy of AZD5582 in inducing SIV reactivation, demonstrate enhancement of latency reversal when AZD5582 is used in combination with N-803 and show a reduction in total and replication-competent SIV-DNA in lymph-node-derived CD4+ T cells in macaques treated with AZD5582 + RhmAbs. Further exploration of this therapeutic approach may contribute to the goal of achieving an HIV cure.

Machine learning methods to predict presence of residual cancer following hysterectomy.

Surgical management for gynecologic malignancies often involves hysterectomy, often constituting the most common gynecologic surgery worldwide. Despite maximal surgical and medical care, gynecologic malignancies have a high rate of recurrence following surgery. Current machine learning models use advanced pathology data that is often inaccessible within low-resource settings and are specific to singular cancer types. There is currently a need for machine learning models to predict non-clinically evident residual disease using only clinically available health data. Here we developed and tested multiple machine learning models to assess the risk of residual disease post-hysterectomy based on clinical and operative parameters. Data from 3656 hysterectomy patients from the NSQIP dataset over 14 years were used to develop models with a training set of 2925 patients and a validation set of 731 patients. Our models revealed the top postoperative predictors of residual disease were the initial presence of gross abdominal disease on the diaphragm, disease located on the bowel mesentery, located on the bowel serosa, and disease located within the adjacent pelvis prior to resection. There were no statistically significant differences in performances of the top three models. Extreme gradient Boosting, Random Forest, and Logistic Regression models had comparable AUC ROC (0.90) and accuracy metrics (87-88%). Using these models, physicians can identify gynecologic cancer patients post-hysterectomy that may benefit from additional treatment. For patients at high risk for disease recurrence despite adequate surgical intervention, machine learning models may lay the basis for potential prospective trials with prophylactic/adjuvant therapy for non-clinically evident residual disease, particularly in under-resourced settings.

Sensitive and selective detection of peanut allergen Ara h 1 by ELISA and lateral flow immunoassay.

The Ara h1 protein is a peanut allergen and it provides a useful biomarker for the detection of peanut protein. In this manuscript, we describe the generation of monoclonal antibodies (MAbs) against the Ara h1 protein and their development into sensitive and selective immunoassays for peanut detection. Our enzyme-linked immunosorbent assay (sELISA) detects a peanut meal standard with a sensitivity of 10 ng/mL and 500 ng/mL by lateral flow immunoassay (LFIA). MAb Ara h1 binding epitopes were identified, and immunoassay detection was limited to peanut meal varieties irrespective of thermal treatment. No binding was observed from tree nut meals (100-0.4 µg/mL). Peanut allergen detection during food manufacturing can limit the incidence of product recall resulting from cross-contact contamination or improper labeling of finished food products. Detection of Ara h1 by immunoassay can provide a cost-effective method for rapid surveillance of peanut during food production and prior to consumption.

A Review of Functional Restoration From Spinal Cord Stimulation in Patients With Spinal Cord Injury.

Traumatic spinal cord injury often leads to loss of sensory, motor, and autonomic function below the level of injury. Recent advancements in spinal cord electrical stimulation (SCS) for spinal cord injury have provided potential avenues for restoration of neurologic function in affected patients. This review aims to assess the efficacy of spinal cord stimulation, both epidural (eSCS) and transcutaneous (tSCS), on the return of function in individuals with chronic spinal cord injury. The current literature on human clinical eSCS and tSCS for spinal cord injury was reviewed. Seventy-one relevant studies were included for review, specifically examining changes in volitional movement, changes in muscle activity or spasticity, or return of cardiovascular pulmonary, or genitourinary autonomic function. The total participant sample comprised of 327 patients with spinal cord injury, each evaluated using different stimulation protocols, some for sensorimotor function and others for various autonomic functions. One hundred eight of 127 patients saw improvement in sensorimotor function, 51 of 70 patients saw improvement in autonomic genitourinary function, 32 of 32 patients saw improvement in autonomic pulmonary function, and 32 of 36 patients saw improvement in autonomic cardiovascular function. Although this review highlights SCS as a promising therapeutic neuromodulatory technique to improve rehabilitation in patients with SCI, further mechanistic studies and stimulus parameter optimization are necessary before clinical translation.

Machine learning models to prognose 30-Day Mortality in Postoperative Disseminated Cancer Patients.

Patients with disseminated cancer at higher risk for postoperative mortality see improved outcomes with altered clinical management. Being able to risk stratify patients immediately after their index surgery to flag high risk patients for healthcare providers is vital. The combination of physician uncertainty and a demonstrated optimism bias often lead to an overestimation of patient life expectancy which can precent proper end of life counseling and lead to inadequate postoperative follow up. In this cohort study of 167,474 postoperative patients with multiple types of disseminated cancer, patients at high risk of 30-day postoperative mortality were accurately identified using our machine learning models based solely on clinical features and preoperative lab values. Extreme Gradient Boosting, Random Forest, and Logistic Regression machine learning models were developed on the cohort. Among 167,474 disseminated cancer patients, 50,669 (30.3%) died within 30 days of their index surgery; After preprocessing, 28 features were included in the model development. The cohort was randomly divided into 133,979 patients (80%) for training the models and 33,495 patients (20%) for testing. The extreme gradient boosting model had an AUC of 0.93 (95% CI: 0.926-0.931), the random forest model had an AUC of 0.93 (95% CI: 0.930-0.934), and the logistic regression model had an AUC of 0.90 (95% CI: 0.900-0.906 the index operation. Ultimately, Machine learning models were able to accurately predict short-term postoperative mortality among a heterogenous population of disseminated cancer patients using commonly accessible medical features. These models can be included in electronic health systems to guide clinical judgements that affect direct patient care, particularly in low-resource settings.

Outcomes of Early Versus Late Tracheostomy in Patients With COVID-19: A Multinational Cohort Study.

Timing of tracheostomy in patients with COVID-19 has attracted substantial attention. Initial guidelines recommended delaying or avoiding tracheostomy due to the potential for particle aerosolization and theoretical risk to providers. However, early tracheostomy could improve patient outcomes and alleviate resource shortages. This study compares outcomes in a diverse population of hospitalized COVID-19 patients who underwent tracheostomy either "early" (within 14 d of intubation) or "late" (more than 14 d after intubation). DESIGN: International multi-institute retrospective cohort study. SETTING: Thirteen hospitals in Bolivia, Brazil, Spain, and the United States. PATIENTS: Hospitalized patients with COVID-19 undergoing early or late tracheostomy between March 1, 2020, and March 31, 2021. INTERVENTIONS: Not applicable. MEASUREMENTS AND MAIN RESULTS: A total of 549 patients from 13 hospitals in four countries were included in the final analysis. Multivariable regression analysis showed that early tracheostomy was associated with a 12-day decrease in time on mechanical ventilation (95% CI, -16 to -8; p < 0.001). Further, ICU and hospital lengths of stay in patients undergoing early tracheostomy were 15 days (95% CI, -23 to -9 d; p < 0.001) and 22 days (95% CI, -31 to -12 d) shorter, respectively. In contrast, early tracheostomy patients experienced lower risk-adjusted survival at 30-day post-admission (hazard ratio, 3.0; 95% CI, 1.8-5.2). Differences in 90-day post-admission survival were not identified. CONCLUSIONS: COVID-19 patients undergoing tracheostomy within 14 days of intubation have reduced ventilator dependence as well as reduced lengths of stay. However, early tracheostomy patients experienced lower 30-day survival. Future efforts should identify patients most likely to benefit from early tracheostomy while accounting for location-specific capacity.