RESUMO
OBJECTIVE: The study assesses user acceptance and effectiveness of a surgeon-authored virtual reality (VR) training module authored by surgeons using the Toolkit for Illustration of Procedures in Surgery (TIPS). METHODS: Laparoscopic adrenalectomy was selected to test the TIPS framework on an unusual and complex procedure. No commercial simulation module exists to teach this procedure. A specialist surgeon authored the module, including force-feedback interactive simulation, and designed a quiz to test knowledge of the key procedural steps. Five practicing surgeons, with 15 to 24 years of experience, peer reviewed and tested the module. In all, 14 residents and 9 fellows trained with the module and answered the quiz, preuse and postuse. Participants received an overview during Surgical Grand Rounds session and a 20-minute one-on-one tutorial followed by 30 minutes of instruction in addition to a force-feedback interactive simulation session. Additionally, in answering questionnaires, the trainees reflected on their learning experience and their experience with the TIPS framework. RESULTS: Correct quiz response rates on procedural steps improved significantly postuse over preuse. In the questionnaire, 96% of the respondents stated that the TIPS module prepares them well or very well for the adrenalectomy, and 87% indicated that the module successfully teaches the steps of the procedure. All participants indicated that they preferred the module compared to training using purely physical props, one-on-one teaching, medical atlases, and video recordings. CONCLUSIONS: Improved quiz scores and endorsement by the participants of the TIPS adrenalectomy module establish the viability of surgeons authoring VR training.
Assuntos
Adrenalectomia/educação , Feedback Formativo , Laparoscopia/educação , Treinamento por Simulação , Atitude do Pessoal de Saúde , Competência Clínica , Simulação por Computador , Currículo , Humanos , Transferência de Experiência , Interface Usuário-ComputadorRESUMO
BACKGROUND: A standardized scoring system does not exist in virtual reality-based assessment metrics to describe safe and crucial surgical skills in robot-assisted surgery. This study aims to develop an assessment score along with its construct validation. MATERIALS AND METHODS: All subjects performed key tasks on previously validated Fundamental Skills of Robotic Surgery curriculum, which were recorded, and metrics were stored. After an expert consensus for the purpose of content validation (Delphi), critical safety determining procedural steps were identified from the Fundamental Skills of Robotic Surgery curriculum and a hierarchical task decomposition of multiple parameters using a variety of metrics was used to develop Robotic Skills Assessment Score (RSA-Score). Robotic Skills Assessment mainly focuses on safety in operative field, critical error, economy, bimanual dexterity, and time. Following, the RSA-Score was further evaluated for construct validation and feasibility. Spearman correlation tests performed between tasks using the RSA-Scores indicate no cross correlation. Wilcoxon rank sum tests were performed between the two groups. RESULTS: The proposed RSA-Score was evaluated on non-robotic surgeons (n = 15) and on expert-robotic surgeons (n = 12). The expert group demonstrated significantly better performance on all four tasks in comparison to the novice group. Validation of the RSA-Score in this study was carried out on the Robotic Surgical Simulator. CONCLUSION: The RSA-Score is a valid scoring system that could be incorporated in any virtual reality-based surgical simulator to achieve standardized assessment of fundamental surgical tents during robot-assisted surgery.
Assuntos
Educação de Pós-Graduação em Medicina/métodos , Educação de Pós-Graduação em Medicina/normas , Avaliação Educacional/métodos , Avaliação Educacional/normas , Cirurgia Geral/educação , Robótica/educação , Adulto , Educação Baseada em Competências/métodos , Educação Baseada em Competências/normas , Simulação por Computador/normas , Feminino , Humanos , Internato e Residência/métodos , Internato e Residência/normas , Masculino , Estudos Prospectivos , Interface Usuário-ComputadorRESUMO
OBJECTIVE: To assess whether TNODS is an independent prognostic factor after adjusting for the lymph node ratio (LNR). SUMMARY BACKGROUND DATA: The medical literature has suggested that the TNODS is associated with better survival in stage II and III colon cancer. Thus TNODS was endorsed as a quality measure for patient care by American College of Surgeons, National Quality Forum. There is, however, little biologic rationale to support this linkage. METHODS: : A total of 24,477 stage III colon cancer patients were identified from Surveillance, Epidemiology, and End Results cancer registry and categorized into 4 groups, LNR1 to LNR4, according to LNR interval: <0.07, 0.07 to 0.25, 0.25 to 0.50, and >0.50. Patients were also stratified according to TNODS into high TNODS (> or = 12) and low TNODS (<12) groups. The method of Kaplan-Meier was used to estimate the 5-year survival and the log-rank test was used to test the survival difference among the different groups. RESULTS: Patients with high TNODS have better survival compared with those with low TNODS (5-year survival 51.0% vs. 45.0%, P < 0.0001). However, after stratifying by LNR status, there was no significant survival difference between patients with high TNODS and those with low TNODS within strata LNR2 (5-year survival 56.3% vs. 56.0%, P = 0.26). Ironically, patients with high TNODS had significantly worse survival than those with low TNODS within strata LNR3 (5-year survival 41.2% vs. 47.4%, P = 0.0009) and LNR 4 (5-year survival 22.0% vs. 32.1%, P < 0.0001). CONCLUSIONS: The previously reported prognostic effect of TNODS on node-positive colon cancer was confounded by LNR. This observation calls into question the use of TNODS as a quality measure for colon cancer patients' care.
Assuntos
Neoplasias do Colo/mortalidade , Neoplasias do Colo/patologia , Linfonodos/patologia , Invasividade Neoplásica/patologia , Indicadores de Qualidade em Assistência à Saúde , Adulto , Fatores Etários , Idoso , Idoso de 80 Anos ou mais , Análise de Variância , Neoplasias do Colo/terapia , Terapia Combinada , Intervalo Livre de Doença , Feminino , Humanos , Excisão de Linfonodo , Linfonodos/cirurgia , Masculino , Pessoa de Meia-Idade , Estadiamento de Neoplasias , Valor Preditivo dos Testes , Probabilidade , Prognóstico , Modelos de Riscos Proporcionais , Sistema de Registros , Estudos Retrospectivos , Medição de Risco , Programa de SEER , Sensibilidade e Especificidade , Fatores Sexuais , Análise de Sobrevida , Resultado do Tratamento , Adulto JovemRESUMO
BACKGROUND: Recent literature has shown that lymph node ratio (LNR) is superior to the number of positive lymph nodes (pLNs) in predicting the prognosis in several malignances other than colon cancer. We hypothesize that LNR may play a similar role in stage III colon cancer. METHODS: We included 24,477 stage III colon cancer cases from the Surveillance, Epidemiology, and End Results cancer registry. Patients were categorized into four groups, LNR1 to 4, according to cutoff points 1/14, 0.25, and 0.50. Kaplan-Meier and Cox proportional hazard model were used to evaluate the prognostic effect and estimate the relative risk (RR) and 95% confidence interval (CI) of LNR. RESULTS: The 5-year survival for patients with stage IIIA, IIIB, and IIIC was 71.3%, 51.7%, and 34.0%, respectively (P < .0001). There was no survival difference among LNR1 to LNR4 for stage IIIA patients. In stage IIIB patients, the 5-year survival for those with LNR1 to LNR4 was 63.5%, 54.7%, 44.4%, and 34.2%, respectively (P < .0001). In stage IIIC patients, the 5-year survival for those with LNR2 to LNR4 was 49.6%, 41.7%, and 25.2%, respectively (P < .0001). LNR is an independent predictor of survival after adjusting patient's age, tumor size, tumor grade, race, number of pLNs, and total number of LNs harvested. (RR 2.30, 95% CI 2.08-2.55). CONCLUSION: Patients with stage IIIB and IIIC colon cancer represent a heterogeneous group of patients with the majority either overstaged or understaged. LNR is a more accurate prognostic method for stage III colon cancer patients. We propose an algorithm to incorporate LNR into current AJCC staging system.
Assuntos
Neoplasias do Colo/patologia , Linfonodos/patologia , Estadiamento de Neoplasias/métodos , Idoso , Idoso de 80 Anos ou mais , Algoritmos , Feminino , Humanos , Metástase Linfática , Masculino , Pessoa de Meia-Idade , Prognóstico , Estudos Retrospectivos , Programa de SEER , Análise de Sobrevida , Estados UnidosRESUMO
OBJECTIVES: Central venous catheter (CVC) and chest tube (CT) insertions are common bedside procedures frequently performed by surgery residents. Despite published guidelines, variability in the practice exists. We sought to characterize the surgery residents' practice patterns surrounding these two bedside procedures. MATERIALS AND METHODS: Over the last 1½ months of the academic year in 2012 and 2013, surgery residents across the US were surveyed online. Participants reported levels of agreement for 15 questions in a 5-point Likert scale format. RESULTS: A total of 219 residents completed the survey. Majority of residents agreed that they received appropriate education and training. Over half of the respondents reported that they did not have attending staff physician's supervision during the procedures. Junior residents felt less confident in performing CVC or CT insertions. Those younger than 29 years old and of female sex were also less confident in performing CT insertion. Although almost all residents reported using maximal sterile barrier precautions, 7% reported not securing their gowns and another 7% reported inadequate draping of patients. About â reported no hand cleansing before the procedures. Those from community programs compared to university programs less frequently used antibiotics. Sixty-five percent of residents reported routine use of ultrasound for CVC insertion. CONCLUSION: Surgery residents do not strictly adhere to the guidelines for CVC and CT insertions, and there is substantial variation in the practice of the procedures, which may contribute to complications associated with these procedures. This survey opens new areas for in-service education, feedback, and practices for these procedures to reduce the risk of complications, especially the infectious one.
RESUMO
BACKGROUND: This project was designed to determine the growth of interpersonal skills during the first year of a surgical residency. METHODS: All categorical surgical residents were given a clinical skills examination of abdominal pain using standardized patients during their orientation (T1). The categorical residents were retested after 11 months (T2). The assessment tool was based on a 12-item modified version of the 5-point Likert Interpersonal Scale (IP) used on the National Board of Medical Examiners prototype Clinical Skills Examination and a 24-item, done-or-not-done, history-taking checklist. Residents' self-evaluation scores were compared to standardized patients' assessment scores. Data were analyzed using the Pearson correlation coefficient, Wilcoxon signed rank test, Student t test, and Cronbach alpha. RESULTS: Thirty-eight categorical residents were evaluated at T1 and T2. At T1, in the history-taking exercise, the scores of the standardized patients and residents correlated (Pearson = .541, P = .000). In the interpersonal skills exercise, the scores of the standardized patients and residents did not correlate (Pearson = -0.238, P = .150). At T2, there was a significant improvement in the residents' self-evaluation scores in both the history-taking exercise (t = -3.280, P = .002) and the interpersonal skills exercise (t = 2.506, P = 0.017). In the history-taking exercise, the standardized patients' assessment scores correlated with the residents' self-evaluation scores (Pearson = 0.561, P = .000). In the interpersonal skills exercise, the standardized patients' assessment scores did not correlate with the residents' self-evaluation scores (Pearson = 0.078, P = .646). CONCLUSIONS: Surgical residents demonstrate a consistently low level of self-awareness regarding their interpersonal skills. Observed improvement in resident self-evaluation may be a function of growth in self-confidence.
Assuntos
Cirurgia Geral/educação , Internato e Residência/métodos , Relações Interpessoais , Relações Médico-Paciente , Dor Abdominal/cirurgia , Educação de Pós-Graduação em Medicina/métodos , Humanos , Anamnese , Autoavaliação (Psicologia)RESUMO
Severe ischemia of the upper extremity causing tissue necrosis occurs much less frequently than in the lower extremity. The clinical outcome of patients diagnosed with digital nonhealing ulcer or gangrene is largely unknown. A retrospective review of patients with upper extremity tissue loss was performed. Patients with ischemia from embolic disease, steal syndromes, and vasospastic or connective tissue disorders were excluded. Thirteen patients with upper extremity ischemic gangrene and/or nonhealing ulcers were treated from January 1995 to June 2002. Comorbid conditions included diabetes mellitus in 10 patients and renal failure in 11 patients. Five patients developed bilateral upper extremity ischemia during the period of evaluation, while 8 had unilateral involvement. Nine patients had dry gangrene of a digit, 5 had nonhealing ulcers, and 1 patient developed wet gangrene from an ischemic ulcer. All 13 patients received local wound care and medical treatment with anticoagulants, calcium channel blockers, or antiplatelet agents. Ischemic lesions healed in 3 of the 5 patients with conservative management. Surgical intervention was performed on 6 patients with dry gangrene, and the patient with wet gangrene underwent amputation of the hand (53.8%). Two patients underwent sympathectomy without improvement. In the remaining 3 patients, tissue loss remained stable. Seven patients died within 2 years of presentation with upper extremity ischemia, with a survival at 24 months of only 14% by lifetable analysis. The local outcome of severe upper extremity ischemia is generally favorable, with good response to either medical management or digit amputation. However, the life expectancy of the patients with upper extremity ischemia from true atherosclerotic disease is dismal. Therefore, surgical intervention should be reserved for infection control or pain relief only.
Assuntos
Arteriosclerose/mortalidade , Isquemia/terapia , Úlcera/terapia , Extremidade Superior/irrigação sanguínea , Adulto , Idoso , Idoso de 80 Anos ou mais , Arteriosclerose/complicações , Arteriosclerose/epidemiologia , Comorbidade , Diabetes Mellitus/epidemiologia , Feminino , Humanos , Isquemia/etiologia , Isquemia/mortalidade , Falência Renal Crônica/epidemiologia , Masculino , Pessoa de Meia-Idade , Necrose , Avaliação de Resultados em Cuidados de Saúde , Estudos Retrospectivos , Análise de Sobrevida , Úlcera/etiologia , Extremidade Superior/patologiaRESUMO
BACKGROUND: Regulatory requirements for resident working hours were designed to improve patient care. Compliance challenges a training program to meet procedural and clinical requirements. This is a retrospective study of a 5-year experience in addressing the challenges and studying the impact of compliance on resident caseload and board performance. METHODS: Our surgical program adopted strict start/stop working hours for clinical contact. Program leadership modified the program to establish procedural and performance criteria. Procedures were prioritized and assignments were changed to maximize clinical and procedural experience while reducing redundancy of experience. Procedural activity was monitored frequently. Compliance with working hour regulations was monitored and behavior modified where necessary. A web based computer program was developed to improve measurement of compliance and provide feedback. Outcome measures included both the number of procedures as reported by the ACGME and performance on the American Board of Surgery, Qualifying Examination. RESULTS: Working hour compliance is greater than 95%. First time pass rate on the Qualifying examination is 90% (45/50). There is no significant difference in the procedural activity. CONCLUSION: Complying with working hour regulations improves the quality of a resident's life and can be achieved while maintaining procedural experience and guaranteeing academic development.
Assuntos
Cirurgia Geral/educação , Internato e Residência/organização & administração , Internato e Residência/normas , Admissão e Escalonamento de Pessoal/legislação & jurisprudência , Cirurgia Geral/legislação & jurisprudência , Humanos , New York , Garantia da Qualidade dos Cuidados de SaúdeRESUMO
BACKGROUND: To evaluate hospital costs and reimbursement for open (OAAA) and endovascular (EVAAA) repair of abdominal aortic aneurysm. STUDY DESIGN: Review of all patients who underwent OAAA or EVAAA in two teaching hospitals during the period January 1, 2000, to December 31, 2000, was completed for the following: demographics, Diagnosis Related Group (DRG), resource use, length of stay, hospital costs, and reimbursement data. RESULTS: There were 130 abdominal aortic aneurysm procedures performed. Fifty-seven (44%) OAAA were completed; EVAAA was attempted in 73 (56%). Seventy EVAAA patients (96%) had endografts placed, and three (4%) required conversion to open repair. Significant differences were noted between OAAA and EVAAA in operative time (311.7 +/- 107.5 minutes versus 263.4 +/- 110.8 minutes, respectively, p = 0.02), ICU admission and length of stay (100%, 5.0 +/- 6.1 days versus 29%, 1.4 +/- 7.1 days, respectively, p = 0.003), and hospital length of stay (12.6 +/- 14.8 days versus 4.9 +/- 13.4 days, respectively, p = 0.002). Total costs were $17,539.00 for EVAAA and $9,042.00 for OAAA. EVAAA was profitable ($3,072.00) for Medicare DRG 110 classification, but significant loss occurred with DRG 111 ($5,065.00). Contract renegotiation with private payers (to cover graft costs) was necessary to avoid substantial per- patient loss ($12,108.00). Overall net per-patient profit for EVAAA was $737.00. CONCLUSIONS: Endovascular abdominal aortic aneurysm repair is significantly more expensive than open repair, with the major portion attributed to graft cost. Although ICU use and total length of stay decreased with EVAAA, overall costs were not substantially reduced. Hospitals must develop new financial strategies and improve the efficiency of their infrastructures in order to offer EVAAA.
Assuntos
Aneurisma da Aorta Abdominal/economia , Aneurisma da Aorta Abdominal/cirurgia , Implante de Prótese Vascular/economia , Custos Hospitalares , Procedimentos Cirúrgicos Vasculares/economia , Análise Custo-Benefício , Humanos , Reembolso de Seguro de Saúde/economia , Estudos RetrospectivosRESUMO
The efficacy and safety of intravenous (IV) ertapenem, 1 and 1.5 g once a day, for treatment of adults with complicated intra-abdominal infection were compared with those of IV ceftriaxone 2 g once a day plus IV metronidazole 500 mg every 8 h. After at least 3 days of IV therapy and satisfactory clinical response, patients could be switched to oral ciprofloxacin plus metronidazole. Fifty-nine patients were randomized to receive ertapenem 1 g and 51 to receive ertapenem 1.5 g; 55 patients were randomized to each comparator group. At the test of cure, 4-6 weeks post therapy, in the 1 g cohort, 84% (26/31) of patients treated with ertapenem and 85% (35/41) with comparator therapy had a favourable clinical and microbiological assessment. Success rates in the 1.5 g cohort were 83% (22/29) and 77% (24/31) in the ertapenem and comparator groups, respectively. Drug-related adverse events were generally similar in both treatment groups. Ertapenem 1 or 1.5 g once a day followed by optional oral therapy appeared similar to combined therapy with ceftriaxone plus metronidazole with the same optional oral switch for treatment of complicated intra-abdominal infections in adults. Although not compared directly in a randomized fashion, the efficacy and safety profiles of ertapenem 1 and 1.5 g appeared comparable. Ertapenem was generally well tolerated and had an overall safety profile similar to ceftriaxone plus metronidazole.
Assuntos
Abdome/microbiologia , Antibacterianos/uso terapêutico , Anti-Infecciosos/uso terapêutico , Infecções Bacterianas/tratamento farmacológico , Ceftriaxona/uso terapêutico , Lactamas , Metronidazol/uso terapêutico , Adolescente , Adulto , Idoso , Antibacterianos/administração & dosagem , Antibacterianos/efeitos adversos , Anti-Infecciosos/administração & dosagem , Anti-Infecciosos/efeitos adversos , Ceftriaxona/administração & dosagem , Ceftriaxona/efeitos adversos , Método Duplo-Cego , Quimioterapia Combinada , Ertapenem , Feminino , Humanos , Injeções Intravenosas , Masculino , Metronidazol/administração & dosagem , Metronidazol/efeitos adversos , Pessoa de Meia-Idade , beta-LactamasRESUMO
OBJECTIVE: To develop and establish effectiveness of simulation-based robotic curriculum--fundamental skills of robotic surgery (FSRS). METHODS: FSRS curriculum was developed and incorporated into a virtual reality simulator, Robotic Surgical Simulator (RoSS). Fifty-three participants were randomized into an experimental group (EG) or control group (CG). The EG was asked to complete the FSRS and 1 final test on the da Vinci Surgical System (dVSS). The dVSS test consisted of 3 tasks: ball placement, suture pass, and fourth arm manipulation. The CG was directly tested on the dVSS then offered the chance to complete the FSRS and re-tested on the dVSS as a crossover (CO) group. RESULTS: Sixty-five percent of participants had never formally trained using laparoscopic surgery. Ball placement: the EG demonstrated shorter time (142 vs 164 seconds, P = .134) and more precise (1.5 vs 2.5 drops, P = .014). The CO took less time (P <.001) with greater precision (P <.001). Instruments were rarely lost from the field. Suture pass: the EG demonstrated better camera utilization (4.3 vs 3.0, P = .078). Less instrument loss occurred (0.5 vs 1.1, P = .026). Proper camera usage significantly improved (P = .009). Fourth arm manipulation: the EG took less time (132 vs 157 seconds, P = .302). Meanwhile, loss of instruments was less frequent (0.2 vs 0.8, P = .076). Precision in the CO improved significantly (P = .042) and camera control and safe instrument manipulation showed improvement (1.5 vs 3.5, 0.2 vs 0.9, respectively). CONCLUSION: FSRS curriculum is a valid, feasible, and structured curriculum that demonstrates its effectiveness by significant improvements in basic robotic surgery skills.
Assuntos
Robótica/educação , Procedimentos Cirúrgicos Urológicos/educação , Adulto , Competência Clínica , Simulação por Computador , Currículo , Avaliação Educacional , HumanosAssuntos
Estado Terminal , Tomada de Decisões , Eutanásia Passiva , Alocação de Recursos para a Atenção à Saúde , Assistência ao Paciente , Seleção de Pacientes , Qualidade de Vida , Reabilitação , Direito a Morrer , Recusa do Paciente ao Tratamento , Ferimentos e Lesões , Tecnologia Biomédica , Cognição , Compreensão , Análise Custo-Benefício , Aconselhamento , Pessoas com Deficiência , Serviços Médicos de Emergência , Família , Liberdade , Humanos , Cuidados para Prolongar a Vida , Competência Mental , Dor , Paternalismo , Pacientes , Autonomia Pessoal , Médicos , Alocação de Recursos , Risco , Medição de Risco , Estresse Psicológico , Valor da VidaRESUMO
BACKGROUND: Attitudes of young surgeons regarding professional organizations are unclear. We surveyed young surgeons to assess their opinions regarding the role of The American College of Surgeons in the future of surgery. METHODS: A 21-question on-line survey was distributed to all young (age <45 years) ACS members. Questions were related to demographics, membership, educational, and health policy initiatives. RESULTS: Among 2689 respondents, reimbursement and malpractice were the most important issues to surgeons at all levels of training. Organizational attributes of importance to young surgeons included leadership, educational tools, mentorship, and avenues to participate in organized medicine. They value programs to address patient safety, surgical quality, reimbursement, and health policy. CONCLUSIONS: Methods to recruit and retain young surgeons into medical organizations should include educational efforts, mentorship programs, practice-management courses, health policy reform, and opportunities for involvement in organizational activities.
Assuntos
Atitude do Pessoal de Saúde , Cirurgia Geral/organização & administração , Padrões de Prática Médica/normas , Sociedades Médicas , Adulto , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Inquéritos e Questionários , Estados UnidosRESUMO
BACKGROUND: Literature showed that lymph node ratio (LNR) and total number of lymph nodes (TNODS) are independent prognostic factors in node-positive colon cancer. Our study assesses the prognostic superiority of the log odds of positive lymph nodes (LODDS) in the same patient population. MATERIAL AND METHODS: A total of 24,477 stage III colon cancer cases from the SEER registry were reviewed. Patients were categorized based on LNR into LNR1 to LNR4, according to cutoff points 0.07, 0.25, and 0.50, and based on LODDS into LODDS1 to LODDS5, according to cutoff points -2.2, -1.1, 0, and 1.1. The relative risk (RR), and 95% confidence interval (CI) were evaluated using the method of Kaplan-Meier and Cox model. RESULTS: Patients with LNR4 could be classified into LODDS4 (61.4%) and LODDS5 (38.4%). The survival in these two groups was significantly different (5-year survival, 33.5% vs. 23.3%, p < 0.0001). Univariate analysis showed that the higher LNR (RR = 3.45, 95% CI = 3.26-3.66) or low TNODS (RR = 0.99, 95% CI = 0.986-0.99) was significantly associated with poor survival. However, after adjusting for LODDS status, the association did not appear to be significant (LNR, RR = 0.90, 95% CI = 0.65-1.24, p = 0.52; TNODS, RR = 1.001, 95% CI = 0.997-1.005, p = 0.54). CONCLUSION: Colon cancer patients with LNR4 disease represent a heterogeneous group. The previously reported prognostic association of TNODS and LNR and outcome of stage III disease were confounded by LODDS.
Assuntos
Neoplasias do Colo/patologia , Linfonodos/patologia , Idoso , Idoso de 80 Anos ou mais , Neoplasias do Colo/mortalidade , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Estadiamento de Neoplasias , Prognóstico , Modelos de Riscos Proporcionais , Estudos Retrospectivos , Programa de SEER , Análise de Sobrevida , Estados UnidosRESUMO
Geostatistics offers two fundamental contributions to environmental contaminant exposure assessment: (1) a group of methods to quantitatively describe the spatial distribution of a pollutant and (2) the ability to improve estimates of the exposure point concentration by exploiting the geospatial information present in the data. The second contribution is particularly valuable when exposure estimates must be derived from small data sets, which is often the case in environmental risk assessment. This article addresses two topics related to the use of geostatistics in human and ecological risk assessments performed at hazardous waste sites: (1) the importance of assessing model assumptions when using geostatistics and (2) the use of geostatistics to improve estimates of the exposure point concentration (EPC) in the limited data scenario. The latter topic is approached here by comparing design-based estimators that are familiar to environmental risk assessors (e.g., Land's method) with geostatistics, a model-based estimator. In this report, we summarize the basics of spatial weighting of sample data, kriging, and geostatistical simulation. We then explore the two topics identified above in a case study, using soil lead concentration data from a Superfund site (a skeet and trap range). We also describe several areas where research is needed to advance the use of geostatistics in environmental risk assessment.