Surgery (Austin & Northern Health) - Research Publications

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    High Frequency, Low Background Rate Extrapleural Programmed Intermittent Bolus Ropivacaine Provides Superior Analgesia Compared with Continuous Infusion for Acute Pain Management Following Thoracic Surgery: A Retrospective Cohort Study.
    Bishop, B ; Pearce, B ; Willshire, L ; Kilpin, M ; Howard, W ; Weinberg, L ; Tan, C (Briefland, 2019-10)
    BACKGROUND: Thoracic surgery often results in severe postoperative pain. Regional analgesia via surgically placed extrapleural local anaesthetic (LA) and continuous infusion (CI) is an effective technique, however usually requires supplemental opioid to achieve satisfactory patient analgesia. We hypothesized that high frequency, low background rate extrapleural programmed intermittent boluses (PIB) of LA by could achieve superior patient analgesia and reduced oral morphine equivalent daily dosage (OMEDD) requirements for up to 3 days after thoracic surgery vs. CI. METHODS: We retrospectively analysed data from 84 adult patients receiving extrapleural analgesia after thoracic surgery in a single tertiary teaching hospital. The primary outcome measure was the effect of PIB vs. CI on maximum daily 11-point numerical rating scale (NRS-11) ratings as determined by multivariate linear regression analysis, corrected for OMEDD use, total daily LA dose, surgery type, age, opioid type, and use of ketamine analgesia. Secondary outcome measures were the effect on OMEDD use, the effect of total 'rescue' LA boluses, and univariate analyses of the above outcomes and variables. RESULTS: PIB on day 0, and a higher proportion of LA given as rescue boluses on day 1 were associated with reduced maximum NRS-11 ratings [standardized/ [unstandardized] beta coefficient -0.34/ [-0.92 NRS-11 if PIB] (P = 0.007); and -0.26/ [-0.029 NRS-11 per mg/kg extrapleural ropivacaine] (P = 0.03)], respectively. Only patient age was associated with reduced OMEDD use [day 0: -0.58/ [-4.4 OMEDDs per year of age] (P ≤ 0.005); day 1: -0.49/ [-3.56 OMEDDs per year of age] (P ≤ 0.005); day 2: -0.32/ [-1.9 OMEDDs per year of age] (P = 0.04)]. OMEDD use on day 2, however, was associated with slightly higher maximum NRS-11 ratings [+0.28/ +0.006 NRS-11 per mg OMEDD (P = 0.036)]. On univariate analysis, PIB patients achieved the largest difference in OMEDD use [-98 mg (95% CI -73 to -123 mg)] and NRS-11 ratings [-1.1 (-0.4 to -1.8)] against CI patients on day 3. CONCLUSIONS: Use of high frequency, low background rate PIB extrapleural LA after thoracic surgery appears to have a modest beneficial effect on acute pain, but not OMEDD use, over CI when adjusted for patient, surgical and other analgesic factors after thoracic surgery. Further work is required to elucidate the potential magnitude of effect that extrapleural LA given by PIB over CI can achieve.
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    Airway strategies for lung isolation in a patient with high-velocity nail gun injuries to the right cardiac ventricle and floor of the mouth: a case report.
    Lim, H ; Weinberg, L ; Tan, CO ; Tay, S ; Kolivas, C ; Peyton, P (Springer Science and Business Media LLC, 2013-05-28)
    INTRODUCTION: We report a case of deliberate self-harm in which three three-inch nails were fired from a nail gun resulting in mandibular fixation and two penetrating injuries to the right cardiac ventricle. This combination of high-velocity penetrating injury has not been previously described. CASE PRESENTATION: A 69-year-old Caucasian man with a medical history of chronic depression was brought to hospital after a failed suicide attempt. The attempt consisted of self-asphyxiation with car exhaust fumes and shooting himself thrice with a three-inch nail gun. He sustained a penetrating nail injury to the floor of his mouth, effectively pinning his mouth closed, and penetrating injuries to the right ventricular free wall and at the junction of the right atrioventricular septum. The patient required emergency surgery with requirements for thoracotomy and sternotomy, lung isolation and cardiopulmonary bypass. CONCLUSIONS: This is the first reported case of a combination high-velocity penetrating nail gun injury to the face and the right cardiac ventricle. This rare case offers airway strategies to accommodate the surgical requirement for lung separation for penetrating chest trauma in a patient with iatrogenically limited mouth opening.
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    The impact of fluid intervention on complications and length of hospital stay after pancreaticoduodenectomy (Whipple's procedure)
    Weinberg, L ; Wong, D ; Karalapillai, D ; Pearce, B ; Tan, CO ; Tay, S ; Christophi, C ; McNicol, L ; Nikfarjam, M (BIOMED CENTRAL LTD, 2014-05-14)
    BACKGROUND: There is limited information on the impact on perioperative fluid intervention on complications and length of hospital stay following pancreaticoduodenectomy. Therefore, we conducted a detailed analysis of fluid intervention in patients undergoing pancreaticoduodenectomy at a university teaching hospital to test the hypothesis that a restrictive intravenous fluid regime and/or a neutral or negative cumulative fluid balance, would impact on perioperative complications and length of hospital stay. METHODS: We retrospectively obtained demographic, operative details, detailed fluid prescription, complications and outcomes data for 150 consecutive patients undergoing pancreaticoduodenectomy in a university teaching hospital. Prognostic predictors for length of hospital stay and complications were determined. RESULTS: One hundred and fifty consecutive patients undergoing pancreaticoduodenectomy were evaluated between 2006 and 2012. The majority of patients were, middle-aged, overweight and ASA class III. Postoperative complications were frequent and occurred in 86 patients (57%). The majority of complications were graded as Clavien-Dindo Class 2 and 3. Postoperative pancreatic fistula occurred in 13 patients (9%), and delayed gastric emptying occurred in 25 patients (17%). Other postoperative surgical complications included sepsis (22%), bile leak (4%), and postoperative bleeding (2%). Serious medical complications included pulmonary edema (6%), myocardial infarction (8%), cardiac arrhythmias (13%), respiratory failure (8%), and renal failure (7%). Patients with complications received a higher median volume of intravenous therapy and had higher cumulative positive fluid balances. Postoperative length of stay was significantly longer in patients with complications (median 25 days vs. 10 days; p < 0.001). After adjustment for covariates, a fluid balance of less than 1 litre on postoperative day 1 and surgeon caseloads were associated with the development of complications. CONCLUSIONS: In the context of pancreaticoduodenectomy, restrictive perioperative fluid intervention and negative cumulative fluid balance were associated with fewer complications and shorter length of hospital stay. These findings provide good opportunities to evaluate strategies aimed at improving perioperative care.
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    Postoperative wristwatch-induced compressive neuropathy of the hand: a case report.
    Weinberg, L ; Spanger, M ; Tan, C ; Nikfarjam, M (Springer Science and Business Media LLC, 2015-06-16)
    INTRODUCTION: Postoperative peripheral nerve injuries are well-recognised complications of both surgery and anaesthesia and a leading cause of litigation claims. We present a rare cause of compressive sensory and motor neuropraxia of the median, ulnar and radial nerves of the right hand resulting from a wristwatch that was worn on the first postoperative night following minor surgery. Mechanisms of this compressive neuropathy are discussed, with specific recommendations made regarding the wearing of wristwatches, jewellery and constrictive clothing in the immediate postoperative period. CASE PRESENTATION: A 12-year-old white boy presented with a complete glove and stocking sensory and motor neuropathy involving his right hand from a wristwatch that was worn on the first postoperative night following uneventful surgery for a minor procedure. Over the following 12 hours the oedema and erythema resolved with complete return of motor function. After 18 hours, the sensory deficit completely resolved. CONCLUSIONS: Postoperative neuropraxia is often preventable. Paediatric patients, especially if thin, may be particularly susceptible to a compression neuropathy from constrictive clothing or jewellery, in particular circumferential varieties such as wristwatches. These items should not be worn in the immediate postoperative period as pressure on peripheral nerves can result in severe and debilitating nerve injury. Education should be given to all medical staff, carers or parents of children undergoing surgery on the avoidance of wearing wristwatches, jewellery or constrictive clothing in the immediate postoperative period. Early medical evaluation of any postoperative nerve injury is of paramount importance.
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    Surgical predictors of acute postoperative pain after hip arthroscopy
    Tan, CO ; Chong, YM ; Tran, P ; Weinberg, L ; Howard, W (BIOMED CENTRAL LTD, 2015-07-02)
    BACKGROUND: Pain following hip arthroscopy is highly variable and can be severe. Little published data exists demonstrating reliable predictors of significant pain after hip arthroscopy. The aim of this study was to identify influence of intraoperative factors (arthroscopic fluid infusion pressure, operative type) on the severity of postoperative pain. METHODS: A retrospective review of 131 patients who had received a variety of arthroscopic hip interventions was performed. A standardized anaesthetic technique was used on all patients and postoperative pain was analysed using recovery pain severity outcomes and analgesic use. A multivariate logistic regression analysis was performed on intraoperative factors including patient age, sex and BMI, arthroscopic infusion pressures (40 vs 80 mm Hg), amount of fluid used, length of surgery and types of arthroscopic interventions performed. Thirty six patients were also prospectively examined to determine arthroscopic fluid infusion rates for 40 and 80 mm Hg infusion pressures. RESULTS: Use of a higher infusion pressure of 80 mm Hg was strongly associated with all pain severity endpoints (OR 2.8 - 8.2). Other significant factors included hip arthroscopy that involved femoral chondro-ostectomy (OR 5.8) and labral repair (OR 7.5). Length of surgery and total amount of infusion fluid used were not associated with increased pain. CONCLUSIONS: 80 mm Hg arthroscopic infusion pressures, femoral chondro-osteoectomy and labral repair are strongly associated with significant postoperative pain, whereas intraoperative infusion volumes or surgical duration are not. Identification of these predictors in individual patients may guide clinical practice regarding the choice of more invasive regional analgesia options. The use of 40 mm Hg arthroscopic infusion pressures will assist in reducing postoperative pain.
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    Plasma-Lyte 148: A clinical review.
    Weinberg, L ; Collins, N ; Van Mourik, K ; Tan, C ; Bellomo, R (Baishideng Publishing Group Inc., 2016-11-04)
    AIM: To outline the physiochemical properties and specific clinical uses of Plasma-Lyte 148 as choice of solution for fluid intervention in critical illness, surgery and perioperative medicine. METHODS: We performed an electronic literature search from Medline and PubMed (via Ovid), anesthesia and pharmacology textbooks, and online sources including studies that compared Plasma-Lyte 148 to other crystalloid solutions. The following keywords were used: "surgery", "anaesthesia", "anesthesia", "anesthesiology", "anaesthesiology", "fluids", "fluid therapy", "crystalloid", "saline", "plasma-Lyte", "plasmalyte", "hartmann's", "ringers" "acetate", "gluconate", "malate", "lactate". All relevant articles were accessed in full. We summarized the data and reported the data in tables and text. RESULTS: We retrieved 104 articles relevant to the choice of Plasma-Lyte 148 for fluid intervention in critical illness, surgery and perioperative medicine. We analyzed the data and reported the results in tables and text. CONCLUSION: Plasma-Lyte 148 is an isotonic, buffered intravenous crystalloid solution with a physiochemical composition that closely reflects human plasma. Emerging data supports the use of buffered crystalloid solutions in preference to saline in improving physicochemical outcomes. Further large randomized controlled trials assessing the comparative effectiveness of Plasma-Lyte 148 and other crystalloid solutions in measuring clinically important outcomes such as morbidity and mortality are needed.
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    The effects of intravenous lignocaine on depth of anaesthesia and intraoperative haemodynamics during open radical prostatectomy.
    Weinberg, L ; Jang, J ; Rachbuch, C ; Tan, C ; Hu, R ; McNicol, L (Springer Science and Business Media LLC, 2017-07-06)
    BACKGROUND: Lignocaine is a local anaesthetic agent, which is also commonly used as a perioperative analgesic adjunct to accelerate rehabilitation and enhance recovery after surgery. Lignocaine's systemic effects on intraoperative haemodynamics and volatile anaesthetic requirements are not well explored. Therefore, we evaluated the effects of intravenous lignocaine on intraoperative volatile agent requirements and haemodynamics in patients undergoing major abdominal surgery. METHODS: We performed an analysis of 76 participants who underwent elective open radical retropubic prostatectomy. Patients received lignocaine (1.5 mg/kg loading dose) followed by an infusion (1.5 mg/kg/h) for the duration of surgery, or saline at an equivalent rate. The aims of the study were to evaluate the end-tidal sevoflurane concentration required to maintain a bispectral index of between 40 and 60. Measurements included intraoperative blood pressure, heart rate, and the volume of intravenous fluids and dosage of vasoactive medications administered. RESULTS: The average end-tidal sevoflurane concentration was lower in the Lignocaine group compared to saline [1.49% (SD: 0.32) vs. 1.89% (SD: 0.29); 95% CI 0.26-0.5, p < 0.001]. In the Lignocaine group, the average mean arterial pressure was 80.3 mmHg (SD: 4.9) compared to 85.1 mmHg (SD: 5.4) in the Saline group (95% CI 2.4-7.1, p < 0.001). Systolic blood pressure was also lower in the Lignocaine group: 121.7 mmHg (SD: 6.1) vs. 128.0 mmHg (SD: 6.4) in the Saline group; 95% CI 3.5-9.2, p < 0.001, as was the mean heart rate [Lignocaine group: 74.9 beats/min (SD: 1.8) vs. 81.5 beats/min (SD: 1.7) in the Saline group, 95% CI 4.1-9.1, p < 0.001]. Maintenance fluid requirements were higher in the Lignocaine group: 3281.1 mL (SD: 1094.6) vs. 2552.6 mL (SD: 1173.5) in the Saline group, 95% CI 206-1251, p = 0.007. There were no differences in the use of vasoactive drugs. CONCLUSIONS: Intravenous lignocaine reduces volatile anaesthetic requirements and lowers blood pressure and heart rate in patients undergoing open radical prostatectomy.
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    Impact of a goal directed fluid therapy algorithm on postoperative morbidity in patients undergoing open right hepatectomy: a single centre retrospective observational study
    Weinberg, L ; Mackley, L ; Ho, A ; Mcguigan, S ; Ianno, D ; Yii, M ; Banting, J ; Muralidharan, V ; Tan, CO ; Nikfarjam, M ; Christophi, C (BMC, 2019-07-31)
    BACKGROUND: Right hepatectomy is a complex procedure that carries inherent risks of perioperative morbidity. To evaluate outcome differences between a low central venous pressure fluid intervention strategy and a goal directed fluid therapy (GDFT) cardiac output algorithm we performed a retrospective observational study. We hypothesized that a GDFT protocol would result in less intraoperative fluid administration, reduced complications and a shorter length of hospital stay. METHODS: Patients undergoing hepatectomy using an established enhanced recovery after surgery (ERAS) programme between 2010 and 2017 were extracted from a prospectively managed electronic hospital database. Inclusion criteria included adult patients, undergoing open right (segments V-VIII) or extended right (segments IV-VIII) hepatectomy. PRIMARY OUTCOME: amount of intraoperative fluid administration used between the two groups. SECONDARY OUTCOMES: type and amount of vasoactive medications used, the development of predefined postoperative complications, hospital length of stay, and 30-day mortality. Complications were defined by the European Perioperative Clinical Outcome definitions and graded according to Clavien-Dindo classification. The association between GDFT and the amount of fluid and vasoactive medication used was investigated using logistic and linear regression models. RESULTS: Fifty-eight consecutive patients were identified. 26 patients received GDFT and 32 received Usual care. There were no significant differences in baseline patient characteristics. Less intraoperative fluid was used in the GDFT group: median (IQR) 2000 ml (1175 to 2700) vs. 2750 ml (2000 to 4000) in the Usual care group; p = 0.03. There were no significant differences in the use of vasoactive medications. Postoperative complications were similar: 9 patients (35%) in the GDFT group vs. 18 patients (56%) in the Usual care group; p = 0.10, OR: 0.41; (95%CI: 0.14 to 1.20). Median (IQR) length of stay for patients in the GDFT group was 7 days (6:8) vs. 9 days (7:13) in the Usual care group; incident rate ratio 0.72 (95%CI: 0.56 to 0.93); p = 0.012. There was no difference in perioperative mortality. CONCLUSIONS: In patients undergoing open right hepatectomy with an established ERAS programme, use of GDFT was associated with less intraoperative fluid administration and reduced hospital length of stay when compared to Usual care. There were no significant differences in postoperative complications or mortality. TRIAL REGISTRATION: Australian New Zealand Clinical Trials Registry: no 12619000558123 on 10/4/19.
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    Relationship between acute hypercarbia and hyperkalaemia during surgery
    Weinberg, L ; Russell, A ; Mackley, L ; Dunnachie, C ; Meyerov, J ; Tan, C ; Li, M ; Hu, R ; Karalapillai, D (BAISHIDENG PUBLISHING GROUP INC, 2019-11-26)
    BACKGROUND: The relationship between hyperkalaemia and metabolic acidosis is well described in the critical care setting; however, the relationship between acute respiratory acidosis and plasma potassium concentration is less well understood. In a controlled model of increasing levels of hypercarbia, we tested the hypothesis of whether increasing levels of hypercarbia are associated with changes in plasma potassium concentrations. AIM: To determine whether increasing levels of hypercarbia are associated with changes in plasma potassium concentrations. METHODS: We performed a post-hoc study examining changes in serum potassium in 24 patients who received increased levels of hypercarbia during cardiac surgery. Arterial blood gases and plasma concentrations of potassium were measured at baseline, 3 min prior to, and then every 3 min for 15 min during the intervention of hypercarbia. The primary endpoint was the absolute change in serum K+ at 15 min compared to the baseline K+ value. The following secondary endpoints were evaluated: (1) The association between CO2 and serum K+ concentration; and (2) The correlation between plasma pH and serum K+ concentrations. RESULTS: During the intervention, PaCO2 increased from 43.6 mmHg (95%CI: 40.1 to 47.1) at pre-intervention to 83.9 mmHg (95%CI: 78.0 to 89.8) at 15 min after intervention; P < 0.0001. The mean (SD) serum potassium increased from 4.16 (0.35) mmol/L at baseline to 4.28 (0.33) mmol/L at 15 min (effect size 0.09 mol/L; P = 0.22). There was no significant correlation between PaCO2 and potassium (Pearson's coefficient 0.06; 95%CI: -0.09 to 0.21) or between pH and potassium (Pearson's coefficient -0.07; 95%CI: -0.22 to 0.09). CONCLUSION: Acute hypercarbia and subsequent respiratory acidaemia were not associated with hyperkalaemia in patients undergoing major surgery.
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    Fluid prescription practices of anesthesiologists managing patients undergoing elective colonoscopy: an observational study.
    Weinberg, L ; Faulkner, M ; Tan, CO ; Liu, DH ; Tay, S ; Nikfarjam, M ; Peyton, P ; Story, D (Springer Science and Business Media LLC, 2014-06-10)
    BACKGROUND: Routine fluid prescription is common practice amongst anesthesiologists caring for patients undergoing colonoscopy. However there is limited information about routine procedural fluid prescription practices of anesthesiologists in this setting. Routine fluid administration may also have important pharmaco-economic implications for the health care budget. Therefore we performed a prospective observational study assessing the fluid prescription practices of anesthesiologists caring for patients undergoing elective colonoscopy. METHODS: With Institutional Review Board approval, adult patients receiving procedural fluid intervention during elective colonoscopy were included. DATA COLLECTED: size of intravenous cannula inserted, volumes of fluid administered, adverse events, procedure duration, and pharmaco-economic costs associated with fluid prescription. Anesthesiologists and gastroenterologists were blinded to the study. RESULTS: We collected data on 289 patients who received fluid prescription by their attending anesthesiologist. Median patient age: 48 yrs (range 18-83), gender: 174 (60%) female; median duration of procedure: 24 minutes (range 12-48). Cannula size: 181 (63%) patients received a 22G cannula or smaller. Median volume of fluid administered during the colonoscopy was 325 ml (range 0 to 1000 ml). Median duration of the procedure: 25 minutes (range 12 to 48 minutes). Median volume of fluid administered in the post anaesthesia recovery unit: 450 ml (range 0 to 1000 ml). Fifteen patients (5%) became hypotensive during the procedure and two patients (<1%) developed hypotension in the PACU. There was no difference in the median fluid requirements between patients with hypotension and those without. Fluid volumes were strongly associated with increasing cannula diameter (p = 0.0001), however there was no association between fluid volumes administered and vasopressor use, peri-procedural adverse events, or procedure duration. At our institution fluid therapy currently cost about AUD$4.90 per patient: 1 L crystalloid $1.18 and fluid delivery set $3.77 Our institution performs over 9000 endoscopic procedures annually with fluid therapy costing about $45,000/year. CONCLUSIONS: Routine fluid prescription by anesthesiologists managing patients undergoing colonoscopy was ineffective with low actual fluid volumes delivered during the procedure. There was no association between volumes of fluid delivered and procedural hypotension, adverse events, or procedure duration. Anesthesiologists should question the clinical and pharmaco-economic value of routine fluid administration for patients undergoing elective endoscopy.