Clinical Focus

  • General Surgery

Academic Appointments

Professional Education

  • Fellowship: UCSF Surgery Fellowships (2022) CA
  • Fellowship: UCSF Surgery Fellowships (2021) CA
  • Residency: Mayo Clinic General Surgery Residency (2020) MN
  • Medical Education: University of Washington School of Medicine (2015) WA

All Publications

  • Small bowel obstruction managed without hospital admission: A safe way to reduce both cost and time in the hospital? Surgery Mahony, C. R., Traynor, M. D., Knight, A. W., Hughes, J. D., Hernandez, M. C., Finnesgard, E. J., Musa, J., Selby, S. L., Rivera, M., Kim, B. D., Heller, S. F., Zielinski, M. D. 2022; 171 (6): 1665-1670


    Small bowel obstruction management has evolved to incorporate the Gastrografin challenge. We expanded its use to the emergency department observation unit, potentially avoiding hospital admission for highly select small bowel obstruction patients. We hypothesized that the emergency department observation unit small bowel obstruction protocol would reduce admissions, costs, and the total time spent in the hospital without compromising outcomes.We reviewed patients who presented with small bowel obstruction from January 2015 to December 2018. Patients deemed to require urgent surgical intervention were admitted directly and excluded. The emergency department observation unit small bowel obstruction guidelines were introduced in November 2016. Patients were divided into pre and postintervention groups based on this date. The postintervention group was further subclassified to examine the emergency department observation unit patients. Cost analysis for each patient was performed looking at number of charges, direct costs, indirect cost, and total costs during their admission.In total, 125 patients were included (mean age 69 ± 14.3 years). The preintervention group (n = 62) and postintervention group (n = 63) had no significant difference in demographics. The postintervention group had a 51% (36.7 hours, P < .001) reduction in median duration of stay and a total cost reduction of 49% (P < .001). The emergency department observation unit subgroup (n = 46) median length of stay was 23.6 hours. The readmission rate was 16% preintervention compared to 8% in the postintervention group (P = .18).Management of highly selected small bowel obstruction patients with the emergency department observation unit small bowel obstruction protocol was associated with decreased length of stay and total cost, without an increase in complications, surgical intervention, or readmissions.

    View details for DOI 10.1016/j.surg.2021.10.041

    View details for PubMedID 34815095

  • Factors associated with receipt of intracranial pressure monitoring in older adults with traumatic brain injury. Trauma surgery & acute care open Ghneim, M., Albrecht, J., Brasel, K., Knight, A., Liveris, A., Watras, J., Michetti, C. P., Haan, J., Lightwine, K., Winfield, R. D., Adams, S. D., Podbielski, J., Armen, S., Zacko, J. C., Nasrallah, F. S., Schaffer, K. B., Dunn, J. A., Smoot, B., Schroeppel, T. J., Stillman, Z., Cooper, Z., Stein, D. M. 2021; 6 (1): e000733


    The Brain Trauma Foundation (BTF) Guidelines for the Management of Severe Traumatic Brain Injury (TBI) include intracranial pressure monitoring (ICPM), yet very little is known about ICPM in older adults. Our objectives were to characterize the utilization of ICPM in older adults and identify factors associated with ICPM in those who met the BTF guidelines.We analyzed data from the American Association for the Surgery of Trauma Geriatric TBI Study, a registry study conducted among individuals with isolated, CT-confirmed TBI across 45 trauma centers. The analysis was restricted to those aged ≥60. Independent factors associated with ICPM for those who did and did not meet the BTF guidelines were identified using logistic regression.Our sample was composed of 2303 patients, of whom 66 (2.9%) underwent ICPM. Relative to Glasgow Coma Scale (GCS) score of 13 to 15, GCS score of 9 to 12 (OR 10.2; 95% CI 4.3 to 24.4) and GCS score of <9 (OR 15.0; 95% CI 7.2 to 31.1), intraventricular hemorrhage (OR 2.4; 95% CI 1.2 to 4.83), skull fractures (OR 3.6; 95% CI 2.0 to 6.6), CT worsening (OR 3.3; 95% CI 1.8 to 5.9), and neurosurgical interventions (OR 3.8; 95% CI 2.1 to 7.0) were significantly associated with ICPM. Restricting to those who met the BTF guidelines, only 43 of 240 (18%) underwent ICPM. Factors independently associated with ICPM included intraparenchymal hemorrhage (OR 2.2; 95% CI 1.0 to 4.7), skull fractures (OR 3.9; 95% CI 1.9 to 8.2), and neurosurgical interventions (OR 3.5; 95% CI 1.7 to 7.2).Worsening GCS, intraparenchymal/intraventricular hemorrhage, and skull fractures were associated with ICPM among older adults with TBI, yet utilization of ICPM remains low, especially among those meeting the BTF guidelines, and potential benefits remain unclear. This study highlights the need for better understanding of factors that influence compliance with BTF guidelines and the risks versus benefits of ICPM in this population.Prognostic and epidemiological, level III.

    View details for DOI 10.1136/tsaco-2021-000733

    View details for PubMedID 34395918

    View details for PubMedCentralID PMC8311332

  • Predicting the Outcome of Non-operative Management of Splenic Trauma in South Africa. World journal of surgery Hernandez, M. C., Traynor, M. D., Knight, A. W., Kong, V. Y., Laing, G. L., Bruce, J. L., Bekker, W., Zielinski, M. D., Clarke, D. L. 2020; 44 (5): 1485-1491


    We aimed to expand on the global surgical discussion around splenic trauma in order to understand locally and clinically relevant factors for operative (OP) and non-operative management (NOM) of splenic trauma in a South African setting.A retrospective cohort study was performed using 2013-2017 data from the Pietermaritzburg Metropolitan Trauma Service. All adult patients (≥15 years) were included. Those managed with OP or NOM for splenic trauma were identified and analyzed descriptively. Multiple logistic regression analysis identified patients and clinical factors associated with management type.There were 127 patients with splenic injury. Median age was 29 [19-35] years with 42 (33%) women and 85 (67%) men. Blunt injuries occurred in the majority (81, 64%). Organ Injury Scale (OIS) grades included I (25, 20%), II (43, 34%), III (36, 28%), IV (15, 11%), and V (8, 6%). Nine patients expired. On univariate analysis, increasing OIS was associated with OP management, need for intensive care unit (ICU) admission, and hospital and ICU duration of stay, but not mortality. In patients with a delayed compared to early presentation, ICU utilization (62% vs. 36%, p = 0.008) and mortality (14% vs. 4%, p = 0.03) were increased. After adjusting for age, sex, presence of shock, and splenic OIS, penetrating trauma (adjusted odds ratio, 5.7; 95%CI, 1.7-9.8) and admission lactate concentration (adjusted odds ratio, 1.4; 95%CI 1.1-1.9) were significantly associated with OP compared to NOM (p = 0.002; area under the curve 0.81).We have identified injury mechanism and admission lactate as factors predictive of OP in South African patients with splenic trauma. Timely presentation to definitive care affects both ICU duration of stay and mortality outcomes. Future global surgical efforts may focus on expanding non-operative management protocols and improving pre-hospital care in patients with splenic trauma.

    View details for DOI 10.1007/s00268-020-05370-z

    View details for PubMedID 31933042

  • Disease Severity and Cost in Adhesive Small Bowel Obstruction. World journal of surgery Hernandez, M. C., Finnesgard, E. J., Shariq, O. A., Knight, A., Stephens, D., Aho, J. M., Kim, B. D., Schiller, H. J., Zielinski, M. D. 2019; 43 (12): 3027-3034


    Adhesive small bowel obstruction (ASBO) severity has been associated with important clinical outcomes. However, the impact of ASBO severity on hospitalization cost is unknown. The American Association for the Surgery of Trauma (AAST) developed an Emergency General Surgery (EGS) disease severity grading system for ASBO. We stratified patients' ASBO severity and captured hospitalization costs hypothesizing that increased disease severity would correlate with greater costs.This was a single-center study of hospitalized adult patients with SBO during 2015-2017. Clinical data and estimated total cost (direct + indirect) were abstracted. AAST EGS grades (I-IV) stratified disease severity. Costs were normalized to the median grade I cost. Univariate and multivariate analyses evaluated the relationship between normalized cost and AAST EGS grade, length of hospital and ICU stay, operative time, and Charlson comorbidity index.There were 214 patients; 119 (56%) were female. AAST EGS grades included: I (62%, n = 132), II (23%, n = 49), III (7%, n = 16), and IV (8%, n = 17). Relative to grade I, median normalized cost increased by 1.4-fold for grade II, 1.6-fold for grade III, and 4.3-fold for grade IV disease. No considerable differences in patient comorbidity between grades were observed. Pair-wise comparisons demonstrated that grade I disease cost less than higher grades (corrected p < 0.001). Non-operative management was associated with lower normalized cost compared to operative management (1.1 vs. 4.5, p < 0.0001). In patients who failed non-operative management, normalized cost was increased 7.2-fold. Collectively, the AAST EGS grade correlated well with cost (Spearman's p = 0.7, p < 0.0001). After adjustment for covariates, AAST EGS grade maintained a persistent relationship with cost.Increasing ASBO severity is independently associated with greater costs. Efforts to identify and mitigate costs associated with this burdensome disease are warranted.III, economic/decision.

    View details for DOI 10.1007/s00268-019-05148-y

    View details for PubMedID 31555867

  • Opioid utilization in minimally invasive versus open inguinal hernia repair. Surgery Knight, A. W., Habermann, E. B., Ubl, D. S., Zielinski, M. D., Thiels, C. A. 2019; 166 (5): 752-757


    Open inguinal hernia repair is thought to cause worse postoperative pain than minimally invasive surgery, and thus patients are often prescribed more opioids at discharge. This study evaluates opioid use in inguinal hernia repair patients to optimize discharge prescribing practices for this common procedure.Opioid-naive adults undergoing open or minimally invasive surgery inguinal hernia repair were identified prospectively from 3 centers to complete a 29-question telephone interview after discharge as part of a larger initiative. Opioid prescription and consumption data were converted into morphine milligram equivalents and compared between minimally invasive surgery and open inguinal hernia repair. Univariate χ2, Fisher exact test, univariate, and multivariable logistic regression were used.Of 249 contacted patients, 195 (74%) completed the survey (n = 97 open, n = 98 minimally invasive surgery). Patients undergoing open inguinal hernia repair were slightly older (71 vs 65 years, P < .001) and less likely to be female (3% vs 17%, P = .001) than minimally invasive surgery patients. Open patients were more likely to have a unilateral inguinal hernia repair (95% open vs 52% minimally invasive surgery, P < .001). Discharge pain scores using the 10-point, patient-reported Numeric Pain Rating scale were similar (open 2.3 ± 1.7 vs minimally invasive surgery 2.4 ± 1.6; P = .80), and most patients were satisfied with postoperative pain control (open 86% vs minimally invasive surgery 95%; P = .13). Open inguinal hernia repair patients were just as likely to receive opioids at discharge as those undergoing minimally invasive surgery inguinal hernia repair (98% vs 91% minimally invasive surgery; P = .06) and were prescribed similar amounts of opioids (open 155 [IQR 113, 225] morphine milligram equivalents vs 150 [IQR 100, 210] minimally invasive surgery; P = .08). There was no difference in opioid use by approach (open 15 [IQR 0, 60] morphine milligram equivalents vs 9 [IQR 0, 50] minimally invasive surgery; P = .33). More than one-third of patients used no opioids (open 38% vs minimally invasive surgery 44%; P = .42). Bilateral repair was not associated with increased opioid use (univariate odds ratio 1.23, P = .58). On multivariable analysis, low discharge pain and normal body mass index were independently associated with needing no opioids at discharge. Overall, 75% of prescribed opioids remained unused at time of survey, yet only 12% of patients had disposed of unused opioids at the time of survey.Postdischarge opioid utilization was clinically similar between patients undergoing open and minimally invasive surgery inguinal hernia repair and those requiring unilateral or bilateral repair. Given that more than one-third of patients required no opioids after discharge, 0 to 8 tablets of 5 mg oxycodone is sufficient for most opioid-naive patients undergoing inguinal hernia repair.

    View details for DOI 10.1016/j.surg.2019.05.012

    View details for PubMedID 31229314

  • The cost burden of clinically significant esophageal anastomotic leaks-a steep price to pay. The Journal of thoracic and cardiovascular surgery Agzarian, J., Visscher, S. L., Knight, A. W., Allen, M. S., Cassivi, S. D., Nichols, F. C., Shen, K. R., Wigle, D., Blackmon, S. H. 2019; 157 (5): 2086-2092


    The purpose of this retrospective cohort study was to evaluate resource consumption of clinically significant esophageal anastomotic leaks.Between September 1, 2008, to December 31, 2014, a prospectively maintained database was queried to identify patients with grade III to IV anastomotic leaks after esophagectomy for esophageal cancer. Inflation-adjusted standardized costs were applied to billed services related to leak diagnosis and treatment, from time of leak detection to resumption of oral diet. A matched analysis was used to compare average expenditures in patients without vs. those with an anastomotic leak.Of 448 patients undergoing esophagectomy after neoadjuvant treatment, 399 patients met inclusion criteria. Twenty-four grade III to IV anastomotic leaks were identified (6% leak rate). Five transhiatal esophagectomies accounted for 20.8% of cases, whereas 9 Ivor Lewis and 10 McKeown esophagectomies accounted for 37.5% and 41.7%, respectively. The median time required to treat an anastomotic leak was 73 days (range 14-701). The additional median standardized cost per leak was $68,296 (mean $119,822). Matched analysis demonstrated that mean treatment costs were 2.6 times greater for patients with an anastomotic leak. This was primarily attributed to prolonged hospitalization, with post-leak detection length of stay ranging from 7 to 73 days. The largest contributors to cost for all patients were intensive care stay (30%), hospital room (17%), pharmacy (16%), and surgical intervention (13%).Grade III to IV esophageal anastomotic leaks more than double the cost of an esophagectomy and have a significant cost burden. Focus should be placed on preventative measures to avoid leaks at the time of the index operation.

    View details for DOI 10.1016/j.jtcvs.2018.10.137

    View details for PubMedID 30558876

  • The ongoing debate regarding optimal nutritional routes following esophagectomy. Journal of thoracic disease Knight, A. W., Blackmon, S. H. 2016; 8 (11): 3006-3008

    View details for DOI 10.21037/jtd.2016.11.56

    View details for PubMedID 28066569

    View details for PubMedCentralID PMC5179412

  • Comparing Robotic Lung Resection With Thoracotomy and Video-Assisted Thoracoscopic Surgery Cases Entered Into The Society of Thoracic Surgeons Database INNOVATIONS-TECHNOLOGY AND TECHNIQUES IN CARDIOTHORACIC AND VASCULAR SURGERY Farivar, A. S., Cerfolio, R. J., Vallieres, E., Knight, A. W., Bryant, A., Lingala, V., Aye, R. W., Louie, B. E. 2014; 9 (1): 10-15


    The use of robotic lung surgery has increased dramatically despite being a new, costly technology with undefined benefits over standard of care. There is a paucity of published comparative articles justifying its use or cost. Furthermore, outcomes regarding robotic lung resection are either from single institutions with in-house historical comparisons or based on limited numbers. We compared consecutive robotic anatomic lung resections performed at two institutions with matched data from The Society of Thoracic Surgeons (STS) National Database for all open and video-assisted thoracoscopic surgery (VATS) resections. We sought to define any benefits to a robotic approach versus national outcomes after thoracotomy and VATS.Data from all consecutive robotic anatomic lung resections were collected from two institutions (n = 181) from January 2010 until January 2012 and matched against the same variables for anatomic resections via thoracotomy (n = 5913) and VATS (n = 4612) from the STS National Database. Patients with clinical N2, N3, and M1 disease were excluded.There was a significant decrease in 30-day mortality and postoperative blood transfusion after robotic lung resection relative to VATS and thoracotomy. The patients stayed in the hospital 2 days less after robotic surgery than VATS and 4 days less than after thoracotomy. Robotic surgery led to fewer air leaks, intraoperative blood transfusions, need for perioperative bronchoscopy or reintubation, pneumonias, and atrial arrhythmias compared with thoracotomy.This is the first comparative analysis using national STS data. It suggests potential benefits of robotic surgery relative to VATS and thoracotomy, particularly in reducing length of stay, 30-day mortality, and postoperative blood transfusion.

    View details for DOI 10.1097/imi.0000000000000043

    View details for Web of Science ID 000217654700002

    View details for PubMedID 24553055

  • The laparoscopic Nissen-Hill hybrid: pilot study of a combined antireflux procedure. Surgical endoscopy Qureshi, A. P., Aye, R. W., Buduhan, G., Knight, A., Orlina, J., Farivar, A. S., Wagner, O. J., McHugh, S., Louie, B. E. 2013; 27 (6): 1945-52


    Laparoscopic antireflux surgery is highly effective in patients with uncomplicated gastroesophageal reflux disease (GERD). However, long-term failure rates in paraesophageal hernia (PEH) and Barrett's metaplasia (BE) are higher and warrant a more durable repair. Outcomes for the laparoscopic Nissen fundoplication (LNF) and Hill repair (LHR) are equivalent, but their anatomic components are different and may complement each other (Aye R Ann Thorac Surg, 2012). We designed and tested the feasibility and safety of an operation that combines the essential components of each repair.A prospective, phase II pilot study was performed on patients with symptomatic giant PEH hernias and/or GERD with nondysplastic Barrett's metaplasia. Pre- and postoperative esophagogastroduodenoscopy (EGD), upper gastrointestinal study (UGI), 48-hour pH testing, manometry, and three quality-of-life metrics were obtained.Twenty-four patients were enrolled in the study. Three patients did not complete the planned procedure, leaving 21 patients, including 12 with PEH, 7 with BE, and 2 with both. There were no 30-day or in-hospital mortalities. At a median follow-up of 13 (range 6.4-30.2) months, there were no reoperations or clinical recurrences. Two patients required postoperative dilation for dysphagia, with complete resolution. Mean DeMeester scores improved from 54.3 to 7.5 (p < 0.0036). Mean lower esophageal sphincter pressures (LESP) increased from 8.9 to 21.3 mmHg (p < 0.013). Mean short-term and long-term QOLRAD scores improved from 4.09 at baseline to 6.04 and 6.48 (p < 0.0001). Mean short-term and long-term GERD-HQRL scores improved from 22.9 to 7.5 and 6.9 (p < 0.03). Mean long-term Dysphagia Severity Score Index improved from 33.3 to 40.6 (p < 0.064).The combination of a Nissen plus Hill hybrid reconstruction of the gastroesophageal junction (GEJ) is technically feasible, safe, and not associated with increased side effects. Short-term clinical results in PEH and BE suggest that this may be an effective repair, supporting the value of further study.

    View details for DOI 10.1007/s00464-012-2692-7

    View details for PubMedID 23306589

  • A randomized multiinstitution comparison of the laparoscopic Nissen and Hill repairs. The Annals of thoracic surgery Aye, R. W., Swanstrom, L. L., Kapur, S., Buduhan, G., Dunst, C. M., Knight, A., Malmgren, J. A., Louie, B. E. 2012; 94 (3): 951-7; discussion 957-8


    Laparoscopic Hill repair (LHR) and laparoscopic Nissen fundoplication (LNF) are established surgical antireflux procedures but have never been compared in a prospective trial. This trial was designed to compare the effectiveness of LHR against the gold-standard LNF.Patients with uncomplicated gastroesophageal reflux from two esophageal centers were randomly assigned and blinded from 2003 to 2007. Preoperative and postoperative evaluation included two quality of life metrics--Quality of Life in Reflux and Dyspepsia, and Dysphagia--as well as endoscopy, video esophogram, manometry, and pH testing.Of 121 patients who consented to the trial, 102 underwent surgery; 46 LNF and 56 LHR were performed, with a mean follow-up of 12 months. Postoperatively, the DeMeester score normalized for both repairs, with no difference between them (LNF 6.8, LHR 11.1, p=0.26). Postoperative medication use was 4%, and the groups were equivalent. Lower esophageal sphincter pressure increased significantly for LNF (14.93 to 24.10, p=0.001) but not for LHR (19.91 to 20.25, p=0.87). Quality of life scores improved significantly for both repairs (LNF 3.77 to 6.65; LHR 3.84 to 6.54, p<0.001), and postoperative results were equivalent (p=0.99). Dysphagia scores preoperative/postoperative were LNF 33.88 to 38.33 and LHR 35.44 to 38.72, and were equivalent postoperatively (p=0.94). Two LNF and two LHR required reoperation for failed repair.The LHR and the LNF both yield excellent and equivalent results for uncomplicated gastroesophageal reflux at 12 months. Their mechanisms of action may be different.

    View details for DOI 10.1016/j.athoracsur.2012.04.083

    View details for PubMedID 22818965