Surgery (Austin & Northern Health) - Research Publications

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    Modern Cardiac Surgical Outcomes in Nonagenarians: A Multicentre Retrospective Observational Study.
    Weinberg, L ; Walpole, D ; Lee, DK ; D'Silva, M ; Chan, JW ; Miles, LF ; Carp, B ; Wells, A ; Ngun, TS ; Seevanayagam, S ; Matalanis, G ; Ansari, Z ; Bellomo, R ; Yii, M (Frontiers Media SA, 2022)
    BACKGROUND: There have been multiple recent advancements in the selection, optimisation and management of patients undergoing cardiac surgery. However, there is limited data regarding the outcomes in nonagenarians, despite this cohort being increasingly referred for these interventions. The objective of this study was to describe the patient characteristics, management and outcomes of a cohort of nonagenarians undergoing cardiac surgery receiving contemporary peri-operative care. METHODS: After receiving ethics approval, we conducted a retrospective observational study of nonagenarians who had undergone cardiac surgery requiring a classic median sternotomy. All operative indications were included. We excluded patients who underwent transcatheter aortic valve implantation (TAVI), and surgery on the thoracic aorta via an endovascular approach (TEVAR). Patients undergoing TEVAR often have the procedure done under sedation and regional blocks with local anesthetic solution. There is no open incision and these patients do not require cardiopulmonary bypass. We also excluded patients undergoing minimally invasive mitral valve surgery via a videoscope assisted approach. These patients do not have a median sternotomy, have the procedure done via erector spinae block, and often are extubated on table. Data were collected from four hospitals in Victoria, Australia, over an 8-year period (January 2012-December 2019). The primary objective was to assess 6-month mortality in nonagenarian patients undergoing cardiac surgery and to provide a detailed overview of postoperative complications. We hypothesized that cardiac surgery in nonagenarian patients would be associated with a 6-month postoperative mortality <10%. As a secondary outcome, we hypothesized that significant postoperative complications (i.e., Clavien Dindo Grade IIIb or greater) would occur in > 30% of patients. RESULTS: A total of 12,358 adult cardiac surgery patients underwent surgery during the study period, of whom 18 nonagenarians (0.15%) fulfilled inclusion criteria. The median (IQR) [min-max] age was 91.0 years (90.0:91.8) [90-94] and the median body mass index was 25.0 (kg/m2) (22.3:27.0). Comorbidities, polypharmacy, and frailty were common. The median predicted mortality as per EuroSCORE-II was 6.1% (4.1:14.5). There were no cases of intra-operative, in-hospital, or 6-month mortality. One (5.6%) patient experienced two Grade IIIa complications. Three (16.7%) patients experienced Grade IIIb complications. Three (16.7%) patients had an unplanned hospital readmission within 30 days of discharge. The median value for postoperative length of stay was 11.6 days (9.8:17.6). One patient was discharged home and all others were discharged to an inpatient rehabilitation facility. CONCLUSION: In this selected, contemporary cohort of nonagenarian patients undergoing cardiac surgery, postoperative 6-month mortality was zero. These findings support carefully selected nonagenarian patients being offered cardiac surgery (Trials Registry: https://www.anzctr.org.au/ACTRN12622000058774.aspx).
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    Intraoperative low tidal volume ventilation and the risk of ICD-10 coded delirium and the use for antipsychotic medications
    Karalapillai, D ; Weinberg, L ; Serpa Neto, A ; Peyton, PJ ; Ellard, L ; Hu, R ; Pearce, B ; Tan, C ; Story, D ; O'Donnell, M ; Hamilton, P ; Oughton, C ; Galtieri, J ; Appu, S ; Wilson, A ; Eastwood, G ; Bellomo, R ; Jones, DA (BMC, 2022-05-16)
    BACKGROUND: Low tidal volume (VT) ventilation and its associated increase in arterial carbon dioxide (PaCO2) may affect postoperative neurologic function. We aimed to test the hypothesis that intraoperative low VT ventilation affect the incidence of postoperative ICD-10 coded delirium and/or the need for antipsychotic medications. METHODS: This is a post-hoc analysis of a large randomized controlled trial evaluating low vs. conventional VT ventilation during major non-cardiothoracic, non-intracranial surgery. The primary outcome was the incidence of ICD-10 delirium and/or the use of antipsychotic medications during hospital stay, and the absolute difference with its 95% confidence interval (CI) was calculated. RESULTS: We studied 1206 patients (median age of 64 [55-72] years, 59.0% males, median ARISCAT of 26 [19-37], and 47.6% of ASA 3). ICD-10 coded delirium and /or antipsychotic medication use was diagnosed in 11.2% with similar incidence between low and conventional VT ventilation (11.1% vs. 11.3%; absolute difference, -0.24 [95%CI, -3.82 to 3.32]; p = 0.894). There was no interaction between allocation group and type of surgery. CONCLUSION: In adult patients undergoing major surgery, low VT ventilation was not associated with increased risk of ICD-10 delirium and/or the use of antipsychotic medications during hospital stay. TRIAL REGISTRATION: ANZCTR Identifier: ACTRN12614000790640 .
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    Serum Creatinine Levels and Nephrocheck® Values With and Without Correction for Urine Dilution-A Multicenter Observational Study
    Hahn, RG ; Yanase, F ; Zdolsek, JH ; Tosif, SH ; Bellomo, R ; Weinberg, L (FRONTIERS MEDIA SA, 2022-02-18)
    BACKGROUND: The Nephrocheck® test is a single-use cartridge designed to measure the concentrations of two novel cell-cycle arrest biomarkers of acute kidney injury, namely tissue inhibitor of metalloproteinase 2 (TIMP-2) and insulin-like growth factor binding protein 7 (IGFBP7). Correlations of serum creatine values and TIMP-2 and IGFBP7 with and without correction for urine dilution have not been previously undertaken in patients undergoing major abdominal surgery. We hypothesized that the Nephrocheck® values would be significantly different with and without correction for urine dilution in patients with elevated creatinine values post major abdominal surgery. METHODS: We performed a post hoc analysis of serum and urine specimens sampled preoperatively and postoperatively in 72 patients undergoing major abdominal surgery. Thirty samples were measured from patients with the greatest decrease and the greatest increase in postoperative serum creatinine values. Urine was analyzed with the Nephrocheck to predict the risk of acute kidney injury (AKIRisk™). We then examined the relationship between serum creatinine and the urinary excretion of TIMP-2 and IGFBP7 as measured by the Nephrocheck test. The AKIRisk between the groups with and without correction for urine dilution was assessed. RESULTS: The median perioperative change in serum creatinine in the two groups was -19% and +57%, respectively. The uncorrected median baseline AKIRisk decreased from 0.70 (25th-75th percentiles, 0.09-1.98) to 0.35 (0.19-0.57) (mg/L)2 in the first group and rose from 0.57 (0.22-1.53) to 0.85 (0.67-2.20) (mg/L)2 in the second group. However, when corrected for the squared urine dilution, the AKIRisk™ in patients with postoperative increases in serum creatinine was not indicative of kidney injury; the corrected AKIRisk was 8.0 (3.2-11.7) μg2/mmol2 before surgery vs.6.9 (5.3-11.0) μg2/mmol2 after the surgery (P = 0.69). CONCLUSION: In the setting of major abdominal surgery, after correction of TIMP-2 and IGFBP7 for urine dilution, the Nephrocheck AKIRisk scores were significantly different from the uncorrected values. These finding imply that the AKIRisk index is a function of urine flow in addition to an increased release of the biomarkers.
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    Intra-operative ventilator mechanical power as a predictor of postoperative pulmonary complications in surgical patients A secondary analysis of a randomised clinical trial
    Karalapillai, D ; Weinberg, L ; Neto A, S ; Peyton, P ; Ellard, L ; Hu, R ; Pearce, B ; Tan, CO ; Story, D ; O'Donnell, M ; Hamilton, P ; Oughton, C ; Galtieri, J ; Wilson, A ; Eastwood, G ; Bellomo, R ; Jones, DA (LIPPINCOTT WILLIAMS & WILKINS, 2022-01)
    BACKGROUND: Studies in critically ill patients suggest a relationship between mechanical power (an index of the energy delivered by the ventilator, which includes driving pressure, respiratory rate, tidal volume and inspiratory pressure) and complications. OBJECTIVE: We aimed to assess the association between intra-operative mechanical power and postoperative pulmonary complications (PPCs). DESIGN: Post hoc analysis of a large randomised clinical trial. SETTING: University-affiliated academic tertiary hospital in Melbourne, Australia, from February 2015 to February 2019. PATIENTS: Adult patients undergoing major noncardiothoracic, nonintracranial surgery. INTERVENTION: Dynamic mechanical power was calculated using the power equation adjusted by the respiratory system compliance (CRS). Multivariable models were used to assess the independent association between mechanical power and outcomes. MAIN OUTCOME MEASURES: The primary outcome was the incidence of PPCs within the first seven postoperative days. The secondary outcome was the incidence of acute respiratory failure. RESULTS: We studied 1156 patients (median age [IQR]: 64 [55 to 72] years, 59.5% men). Median mechanical power adjusted by CRS was 0.32 [0.22 to 0.51] (J min-1)/(ml cmH2O-1). A higher mechanical power was also independently associated with increased risk of PPCs [odds ratio (OR 1.34, 95% CI, 1.17 to 1.52); P < 0.001) and acute respiratory failure (OR 1.40, 95% CI, 1.21 to 1.61; P < 0.001). CONCLUSION: In patients receiving ventilation during major noncardiothoracic, nonintracranial surgery, exposure to a higher mechanical power was independently associated with an increased risk of PPCs and acute respiratory failure. TRIAL REGISTRATION: Australia and New Zealand Clinical Trials Registry no: 12614000790640.
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    Characteristics and outcomes of rapid response team activations for hypotension in orthopaedic patients
    Ramos, JGR ; Zhang, R ; Maher, B ; Hardidge, A ; Weinberg, L ; Robbins, R ; Peyton, PJ ; Bellomo, R ; Jones, D (WILEY, 2020-01)
    BACKGROUND: Hypotension following orthopaedic surgery has been associated with increased morbidity and mortality. Rapid response teams (RRT) review patients on hospital wards with hypotension. AIM: To evaluate the epidemiology of hypotensive RRT activations in adult orthopaedic patients to identify contributing factors and areas for future quality improvement. METHODS: Timing of RRT activations, presumed causes of hypotension and associated treatments were assessed. RESULTS: Among 963 RRT activations in 605 patients over 3 years, the first calls of 226 of 605 patients were due to hypotension, and 213 (94.2%) of 226 had sufficient data for analysis. The median age was 79 (interquartile range 66-87) years; 58 (27.2%) were male, and comorbidities were common. Most (68%) surgery was emergent, and 75.1% received intraoperative vasopressors for hypotension. Most activations occurred within 24 h of surgery, and hypovolaemia, infection and arrhythmias were common presumed causes. Fluid boluses occurred in 173 (81.2%), and the time between surgery and RRT activation was 10 (4.0-26.5) h. in cases where fluid boluses were given, compared with 33 (15.5-61.5) h. where they were not (P < 0.001). Blood transfusion (30, 14.1%) and withholding of medications were also common. Hospital mortality was 8.5% (18), and 13.6% (29) were admitted to critical care at some stage. In-hospital death was associated with older age, functional dependence, arrhythmia and presumed infection. CONCLUSIONS: Hypotension-related RRT calls in orthopaedic patients are common. Future interventional studies might focus on perioperative fluid therapy and vaso-active medications, as well as withholding of anti-hypertensive medications preoperatively.
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    Postoperative complications and hospital costs following small bowel resection surgery
    Lee, D-K ; Frye, A ; Louis, M ; Koshy, AN ; Tosif, S ; Yii, M ; Ma, R ; Nikfarjam, M ; Perini, MV ; Bellomo, R ; Weinberg, L ; Farag, E (PUBLIC LIBRARY SCIENCE, 2020-10-21)
    BACKGROUND: Postoperative complications after major gastrointestinal surgery are a major contributor to hospital costs. Thus, reducing postoperative complications is a key target for cost-containment strategies. We aimed to evaluate the relationship between postoperative complications and hospital costs following small bowel resection. METHODS: Postoperative complications were recorded for 284 adult patients undergoing major small bowel resection surgery between January 2013 and June 2018. Complications were defined and graded according to the Clavien-Dindo classification system. In-hospital cost of index admission was calculated using an activity-based costing methodology; it was reported in US dollars at 2019 rates. Regression modeling was used to investigate the relationships among a priori selected perioperative variables, complications, and costs. FINDINGS: The overall complication prevalence was 81.6% (95% CI: 85.7-77.5). Most complications (69%) were minor, but 22.9% of patients developed a severe complication (Clavien-Dindo grades III or IV). The unadjusted median total hospital cost for patients with any complication was 70% higher than patients without complications (median [IQR] USD 19,659.64 [13,545.81-35,407.14] vs. 11,551.88 [8,849.46-15,329.87], P < 0.001). The development of 1, 2, 3, and ≥ 4 complications increased hospital costs by 11%, 41%, 50%, and 195%, respectively. Similarly, more severe complications incurred higher hospital costs (P < 0.001). After adjustments were made (for the Charlson Comorbidity Index, anemia, surgical urgency and technique, intraoperative fluid administration, blood transfusion, and hospital readmissions), a greater number and increased severity of complications were associated with a higher adjusted median hospital cost. Patients who experienced complications had an adjusted additional median cost of USD 4,187.10 (95% CI: 1,264.89-7,109.31, P = 0.005) compared to those without complications. CONCLUSIONS: Postoperative complications are a key target for cost-containment strategies. Our findings demonstrate a high prevalence of postoperative complications following small bowel resection surgery and quantify their associated increase in hospital costs. TRIAL REGISTRATION: Australian Clinical Trials Registration number: 12620000322932.
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    Assessing TEG6S reliability between devices and across multiple time points: A prospective thromboelastography validation study
    Lloyd-Donald, P ; Churilov, L ; Cheong, B ; Bellomo, R ; McCall, PR ; Martensson, J ; Glassford, N ; Weinberg, L (NATURE PUBLISHING GROUP, 2020-04-27)
    The TEG6S is a novel haemostasis analyser utilising resonance technology. It offers potentially greater coagulation information and ease of use, however has not been independently validated in a clinical setting. We aimed to determine if the TEG6S is reliable between devices and across time points. We performed a prospective observational study with ethical approval. For interdevice reliability, we performed simultaneous analysis on two TEG6S devices on 25 adult ICU patients. For time point reliability, we performed repeated sampling across five different time points on 15 adult participants. Blood was collected with informed consent, or as standard care, before four-channel citrated kaolin analysis. We observed almost perfect interdevice reliability across all TEG parameters. The Lin's concordance correlation coefficients (95% CI, major axis regression slope, intercept) were R-time: 0.96 (0.92-0.99, 0.88, 0.57); K-time: 0.93 (0.87-0.98, 1.07, 0.00); Alpha Angle: 0.87 (0.78-0.96, 1.20, -14.10); Maximum Amplitude: 0.99 (0.98-0.99, 1.02, -1.38); Clot Lysis: 0.89 (0.82-0.97, 1.20, 0.07). Additionally, we observed moderate-to-high reliability across time points. Demonstrating almost perfect agreement across different devices and moderate-to-high reliability across multiple time points, suggests the TEG6S platform can be used with haemostatic accuracy and generalisability. This has potentially significant implications for clinical practice and multi-site research programs.
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    Randomised controlled trial to investigate the relationship between mild hypercapnia and cerebral oxygen saturation in patients undergoing major surgery
    Wong, C ; Churilov, L ; Cowie, D ; Tan, CO ; Hu, R ; Tremewen, D ; Pearce, B ; Pillai, P ; Karalapillai, D ; Bellomo, R ; Weinberg, L (BMJ PUBLISHING GROUP, 2020-02)
    OBJECTIVES: The effects of hypercapnia on regional cerebral oxygen saturation (rSO2) during surgery are unclear. We conducted a randomised controlled trial to investigate the relationship between mild hypercapnia and rSO2. We hypothesised that, compared with targeted normocapnia (TN), targeted mild hypercapnia (TMH) during major surgery would increase rSO2. DESIGN: A prospective, randomised, controlled trial in adult participants undergoing elective major surgery. SETTING: A single tertiary centre in Heidelberg, Victoria, Australia. PARTICIPANTS: 40 participants were randomised to either a TMH or TN group (20 to each). INTERVENTIONS: TMH (partial pressure of carbon dioxide in arterial blood, PaCO2, 45-55 mm Hg) or TN (PaCO2 35-40 mm Hg) was delivered via controlled ventilation throughout surgery. PRIMARY AND SECONDARY OUTCOME MEASURES: The primary endpoint was the absolute difference between the two groups in percentage change in rSO2 from baseline to completion of surgery. Secondary endpoints included intraoperative pH, bicarbonate concentration, base excess, serum potassium concentration, incidence of postoperative delirium and length of stay (LOS) in hospital. RESULTS: The absolute difference between the two groups in percentage change in rSO2 from the baseline to the completion of surgery was 19.0% higher in both hemispheres with TMH (p<0.001). On both sides, the percentage change in rSO2 was greater in the TMH group than the TN group throughout the duration of surgery. The difference between the groups became more noticeable over time. Furthermore, postoperative delirium was higher in the TN group (risk difference 0.3, 95% CI 0.1 to 0.5, p=0.02). LOS was similar between groups (5 days vs 5 days; p=0.99). CONCLUSION: TMH was associated with a stable increase in rSO2 from the baseline, while TN was associated with a decrease in rSO2 in both hemispheres in patients undergoing major surgery. This resulted in a clear separation of percentage change in rSO2 from the baseline between TMH and TN over time. Our findings provide the rationale for larger studies on TMH during surgery. TRIAL REGISTRATION NUMBER: The Australian New Zealand Clinical Trials Registry (ACTRN12616000320459).
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    Comparison of Thromboelastography and Conventional Coagulation Tests in Patients With Severe Liver Disease
    Lloyd-Donald, P ; Vasudevan, A ; Angus, P ; Gow, P ; Martensson, J ; Glassford, N ; Eastwood, GM ; Hart, GK ; Jones, D ; Weinberg, L ; Bellomo, R (SAGE PUBLICATIONS INC, 2020-06-03)
    OBJECTIVE: Thromboelastography (TEG) may provide rapid and clinically important coagulation information in acutely ill patients with chronic liver disease (CLD). Our objective was to describe the relationship between TEG and conventional coagulation tests (CCTs), which has not been previously explored in this population. METHODS: In acutely ill patients with severe CLD (Child-Pugh score > 9, category C), we conducted a prospective observational study investigating coagulation assessment as measured by both CCTs and TEG. We used quantile regression to explore 30 associations between TEG parameters and corresponding CCTs. We compared TEG and CCT measures of coagulation initiation, clot formation, clot strength, and fibrinolysis. RESULTS: We studied 34 patients on a total of 109 occasions. We observed inconsistent associations between TEG and CCT measures of coagulation initiation: TEG (citrated kaolin [CK] assay) standard reaction time and international normalized ratio: R 2 = 0.117 (P = .044). Conversely, there were strong and consistent associations between tests of clot formation: TEG (CK) kinetics time and fibrinogen: R 2 = 0.202 (P < .0001) and TEG (CK) α angle and fibrinogen 0.263 (P < .0001). We also observed strong associations between tests of clot strength, specifically TEG MA and conventional fibrinogen levels, across all TEG assays: MA (CK) and fibrinogen: R 2 = 0.485 (P < .0001). There were no associations between TEG and D-dimer levels. CONCLUSIONS: In acutely ill patients with CLD, there are strong and consistent associations between TEG measures of clot formation and clot strength and conventional fibrinogen levels. There are weak and/or inconsistent associations between TEG and all other conventional measures of coagulation.