Surgery (Austin & Northern Health) - Research Publications

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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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    Reported definitions of intraoperative hypotension in adults undergoing non-cardiac surgery under general anaesthesia: a review
    Weinberg, L ; Li, SY ; Louis, M ; Karp, J ; Poci, N ; Carp, BS ; Miles, LF ; Tully, P ; Hahn, R ; Karalapillai, D ; Lee, D-K (BMC, 2022-03-11)
    BACKGROUND: Intraoperative hypotension (IOH) during non-cardiac surgery is common and associated with major adverse kidney, neurological and cardiac events and even death. Given that IOH is a modifiable risk factor for the mitigation of postoperative complications, it is imperative to generate a precise definition for IOH to facilitate strategies for avoiding or treating its occurrence. Moreover, a universal and consensus definition of IOH may also facilitate the application of novel and emerging therapeutic interventions in treating IOH. We conducted a review to systematically record the reported definitions of intraoperative hypotension in adults undergoing non-cardiac surgery under general anaesthesia. METHODS: In accordance with Cochrane guidelines, we searched three online databases (OVID [Medline], Embase and Cochrane Library) for all studies published from 1 January 2000 to 6 September 2020. We evaluated the number of studies that reported the absolute or relative threshold values for defining blood pressure. Secondary aims included evaluation of the threshold values for defining IOH, the methodology for accounting for the severity of hypotension, whether the type of surgical procedure influenced the definition of IOH, and whether a study whose definition of IOH aligned with the Perioperative Quality Initiative-3 workgroup (POQI) consensus statement for defining was more likely to be associated with determining an adverse postoperative outcome. RESULTS: A total of 318 studies were included in the final qualitative synthesis. Most studies (n = 249; 78.3%) used an absolute threshold to define hypotension; 150 (60.5%) reported SBP, 117 (47.2%) reported MAP, and 12 (4.8%) reported diastolic blood pressure (DBP). 126 (39.6%) used a relative threshold to define hypotension. Of the included studies, 153 (48.1%) did not include any duration variable in their definition of hypotension. Among the selected 318 studies 148 (46.5%) studies defined IOH according to the POQI statement. When studies used a "relative blood pressure change" to define IOH, there was a weaker association in detecting adverse postoperative outcomes compared to studies who reported "absolute blood pressure change" (χ2(2) = 10.508, P = 0.005, Cramér's V = 0.182). When studies used the POQI statement definition of hypotension or defined IOH by values higher than the POQI statement definition there were statistical differences observed between IOH and adverse postoperative outcomes (χ2(1) = 6.581, P = 0.037, Cramér's V = 0.144). When both the duration of IOH or the numbers of hypotensive epochs were evaluated, we observed a significantly stronger relationship between the definition of IOH use the development of adverse postoperative outcomes. (χ2(1) = 4.860, P = 0.027, Cramér's V = 0.124). CONCLUSIONS: Most studies defined IOH by absolute or relative changes from baseline values. There are substantial inconsistencies in how IOH was reported. Further, definitions differed across different surgical specialities. Our findings further suggest that IOH should be defined using the absolute values stated in the POQI statement i.e., MAP < 60-70 mmHg or SBP < 100 mmHg. Finally, the number of hypotensive epochs or time-weighted duration of IOH should also be reported.
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    Serum Creatinine Levels and Nephrocheck (R) 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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    Preliminary experience with continuous right ventricular pressure and transesophageal echocardiography monitoring in orthotopic liver transplantation
    Miles, LF ; Couture, EJ ; Potes, C ; Makar, T ; Fernando, MC ; Hungenahally, A ; Mathieson, MD ; Perlman, H ; Perini, MV ; Thind, D ; Weinberg, L ; Denault, AY ; Lionetti, V (PUBLIC LIBRARY SCIENCE, 2022-02-04)
    BACKGROUND: Despite increasing attention in the cardiac anesthesiology literature, continuous measurement of right ventricular pressure using a pulmonary artery catheter has not been described in orthotopic liver transplantation, despite similarities in the anesthetic approach to the two populations. We describe our preliminary experience with this technique in orthotopic liver transplantation, and by combining various derived measures with trans-esophageal echocardiography, make some early observations regarding the response of these measures of right ventricular function during the procedure. METHODS: In this case series, ten patients (five men and five women) undergoing orthotopic liver transplantation in our institution had their surgeries performed while monitored with a pulmonary artery catheter with continuous right ventricular port transduction and trans-esophageal echocardiography. We recorded various right ventricular waveform (early-to-end diastolic pressure difference, right ventricular outflow tract gradient, right ventricular dP/dT and right ventricular end-diastolic pressure) and echocardiographic (right ventricular fractional area change, tricuspid annular plane systolic excursion, right ventricular lateral wall strain) and described their change relative to baseline at timepoints five minutes before and after portal vein reperfusion, immediately after hepatic artery reperfusion and on abdominal closure. RESULTS: Except for tricuspid annular plane systolic excursion at five minutes prior to reperfusion (mean -0.8 cm; 95% CI-1.4, -0.3; p = 0.007), no echocardiographic metric was statistically significantly different at any timepoint relative to baseline. In contrast, changes in right ventricular outflow tract gradient and right ventricular dP/dt were highly significant at multiple timepoints, generally peaking immediately before or after reperfusion before reducing, but not returning to baseline in the neohepatic phase. Nine of 10 participants in this series demonstrated a degree of dynamic right ventricular outflow tract obstruction, which met criteria for hemodynamic significance (> 25 mmHg) in two participants. These changes were not materially affected by cardiac index. CONCLUSIONS: Dynamic right ventricular outflow tract obstruction of varying severity appears common in patients undergoing orthotopic liver transplantation. These results are hypothesis generating and will form the basis of future prospective research.
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    Rapid response team activation after major hip surgery: A case series.
    Weinberg, L ; Pritchard, A ; Louis, M ; Jones, D ; Hardidge, A ; Churilov, L (Elsevier BV, 2022-01)
    INTRODUCTION: We describe the demographic, preoperative, surgical, anesthetic, and postoperative characteristics of patients who required a rapid response team (RRT) activation after major hip surgery. We determined the characteristics and outcomes of patients that require RRTs after major hip surgery, and their associations with mortality. PRESENTATION OF CASES: We retrospectively reviewed adult patients undergoing major hip surgery in a university teaching hospital. We included patients who had an RRT or "code blue" activation post-surgery and within the index hospital admission. We extracted patient, surgical, anesthetic, and postoperative variables. We explored differences between patients who survived their index hospital stay and those who died. DISCUSSION: 187 (9%) patients had a postoperative RRT activation. The median age was 84.0 (78-90) years; 125 (67%) were female, and most patients had significant comorbidities. The median Charlson Comorbidity Index (CCI) was 5.0 (4.0-7.0). Patients were frail (68%), ASA physical status ≥Class 3 (91%) and underwent emergency surgery (88%). Death after RRT activation occurred in 1 in 7 patients. Compared to patients who survived RRT activation, those who died had a higher mean CCI (6.5 [1.8] vs. 5.5 [2.1], P = 0.02), were more frail (80.1% vs. 56.5%, OR = 3.2, 95% CI: 1.2,8.1; P = 0.03), and received less intraoperative opioids (intravenous morphine equi-analgesia: median = 5.8 (0.1-8.20 vs. 11.7 (3.7-19.0) mg, P = 0.03). CONCLUSION: Mortality after RRT activation is associated with non-modifiable patients factors rather than surgical or anesthesia factors. Our findings provide opportunities for the implementation of strategies aimed at improving postoperative outcomes.
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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 (Ovid Technologies (Wolters Kluwer Health), 2022-01-01)
    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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    A spontaneous retroperitoneal haemorrhage resulting in abdominal compartment syndrome requiring laparotomy: A case report and proposed management algorithm
    Tully, P ; Moshinsky, J ; Spanger, M ; Koshy, AN ; Yii, M ; Weinberg, L (ELSEVIER SCI LTD, 2021-06-15)
    INTRODUCTION AND IMPORTANCE: Spontaneous Retroperitoneal Haemorrhage (SRH) is a rare condition, which in its extreme state can result in Abdominal Compartment Syndrome (ACS). The aim of this case report is to provide an overview of the diagnosis and management of SRH and to present an algorithm to inform and guide clinical decision-making in the context of ACS. CASE PRESENTATION: A 74-year-old woman with multiple risk factors for SRH developed a tense abdomen in ICU post-cardiac graft study. Radiological imaging confirmed multiple bleeding points to the contralateral side of the graft access site. She underwent endovascular treatment for her condition, however, developed ACS necessitating surgical evacuation of the haematoma. CLINICAL DISCUSSION: SRH is a rare condition that may be difficult to diagnose on physical exam. Medical, endovascular and surgical approaches are recognised treatments. ACS is an extreme variant of SRH and although endovascular management can specifically address the acute bleed, surgical evacuation of the haematoma is the only treatment that can effectively reduce abdominal compartment pressures. CONCLUSION: SRH can cause abdominal compartment syndrome with subsequent multiorgan failure. Ultimately, as outlined in this case, surgical evacuation of the haematoma was the only treatment able to reduce abdominal compartment pressures.
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    Fast-track recovery program after cardiac surgery in a teaching hospital: a quality improvement initiative
    Lloyd-Donald, P ; Lee, W-S ; Hooper, JW ; Lee, DK ; Moore, A ; Chandra, N ; McCall, P ; Seevanayagam, S ; Matalanis, G ; Warrillow, S ; Weinberg, L (SPRINGERNATURE, 2021-05-22)
    OBJECTIVE: Fast-track cardiac anesthesia (FTCA) is a technique that may improve patient access to surgery and maximize workforce utilization. However, feasibility and factors impacting FTCA implementation remain poorly explored both locally and internationally. We describe the specific intraoperative and postoperative protocols for our FTCA program, assess protocol compliance and identify reasons for FTCA failure. RESULTS: We tested the program in 16 patients undergoing elective cardiac surgery requiring cardiopulmonary bypass. There was 100% compliance with the FTCA protocols. Four (25%) patients successfully completed the FTCA protocol (extubated < 4 h postoperatively and discharged from the intensive care unit on the same operative day).
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    Effects of a short message service (SMS) by cellular phone to improve compliance with fasting guidelines in patients undergoing elective surgery: a retrospective observational study
    Zia, F ; Cosic, L ; Wong, A ; Levin, A ; Lu, P ; Mitchell, C ; Shaw, M ; Rosewarne, F ; Weinberg, L (BMC, 2021-01-06)
    BACKGROUND: Contemporary perioperative fasting guidelines aim to alleviate patient discomfort before surgery and enhance postoperative recovery whilst seeking to reduce the risk of pulmonary aspiration during anesthesia. The impact of a short message service (SMS) reminder on fasting guideline compliance is unknown. Therefore, we performed a retrospective observational study and quality improvement project aiming to quantify the extent of excessive and prolonged fasting, and then assessed the impact of a SMS reminder in reducing fasting times. METHODS: After ethics committee approval we performed a retrospective observational study investigating preoperative fasting times of adult patients undergoing elective surgery. First, we assessed whether the fasting guideline times were adhered to (Standard Care group). All patients received internationally recommended fasting guidelines in the form of a written hospital policy document. We then implemented an additional prompt via a mobile phone SMS 1 day prior to surgery containing a reminder of fasting guideline times (SMS group). The primary aims were to compare fasting times between the Standard Care group and the SMS group. RESULTS: The fasting times of 160 patients in the Standard Care group and 110 patients in the SMS group were evaluated. Adherence to the fasting guidelines for solids occurred in 14 patients (8.8%) in the Standard Care group vs. Twenty-two patients (13.6%) in the SMS group (p=0.01). Adherence to the fasting guidelines for fluids occurred in 4 patients (2.5%) in the Standard Care group vs. Ten patients (6.3%) in the SMS group (p=0.023). Patients in the Standard Care group had a longer median (inter-quartile range (IQR)) fasting time for fluids compared the SMS group [6.5 h (IQR 4.5:11) vs 3.5 h (IQR 3:8.5), p< 0.0001]. Median fasting times for solids were 11 h (IQR 7:14) in the Standard Care group and 11.5 h (IQR 7:13.5) in the SMS group (p=0.756). CONCLUSION: Adherence to internationally recommended fasting guidelines for patients undergoing elective surgery is poor. The introduction of a fasting guideline reminder via a mobile phone SMS in addition to a written hospital policy improved adherence to fasting advice and reduced the fasting times for fluids but not for solids. The use of an SMS reminder of fasting guidelines is a simple, feasible, low-cost, and effective tool in minimising excessive fasting for fluids among elective surgical patients. TRIAL REGISTRATION: ACTRN12619001232123 (Australia New Zealand Clinical Trials Registry). Registered 6th September 2019 (retrospectively registered).
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    Complete opioid transition to sublingual Buprenorphine after abdominal surgery is associated with significant reductions in opioid requirements, but not reduction in hospital length of stay: a retrospective cohort study
    Heldreich, C ; Ganatra, S ; Lim, Z ; Meyer, I ; Hu, R ; Weinberg, L ; Tan, CO (BMC, 2022-01-21)
    BACKGROUND: The use of sublingual buprenorphine (SLBup) for acute pain after major abdominal surgery may offer the potential advantages of unique analgesic properties and more reliable absorption during resolving ileus. We hypothesized that complete opioid transition to SLBup rather than oral oxycodone (OOxy) in the early postoperative period after major abdominal surgery would reduce hospital length of stay, and acute pain and total OMEDD (Oral Morphine Equivalent Daily Dose) requirements in the first 24 h from post-parenteral opioid transition. METHODS: We reviewed 146 patients who had undergone elective and emergency abdominal surgery under our quaternary referral centre's Upper Gastro-Intestinal and Colo-Rectal Surgical Units 6 months before and after the introduction of complete postoperative transition to sublingual buprenorphine, rather than oral oxycodone, in July 2017. Our primary endpoint was 24-hourly post-transition OMEDDs; secondary endpoints were 24-hourly post-transition Mean NRS-11 pain scores on movement (POM) and length of hospital stay (LOS). Univariate analysis and linear multivariate regression analyses were used to quantify effect size and identify surgical, patient & other analgesic factors associated with these outcome measures. RESULTS: Patients transitioning to SLBup had reduced 24-hourly post-transition OMEDD requirements on postoperative day 2 (POD) (26 mg less, p = 0.04) and NRS-11 POM at POD1 (0.7 NRS-11 units less, p = 0.01). When adjusting for patient, surgical and special analgesic factors, SLBup was associated with a similar reduction in OMEDDs (Unstandardised beta-coefficient -26 mg, p = 0.0001), but not NRS-11 POM (p = 0.47) or hospital LOS (p = 0.16). CONCLUSIONS: Our change of practice from use of OOxy to SLBup as primary transition opioid from patient-controlled analgesia delivered full opioid agonists was associated with a clinically significant decrease in 24-hourly post-parenteral opioid transition OMEDDs and improved NRS-11 POM, but without an association with hospital LOS after major abdominal surgery. Further prospective randomized work is required to confirm these observed associations and impact on other important patient-centred outcomes.