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Papers by John Treacy

Research paper thumbnail of Confidence limits of arteriovenous fistula flow rate measured by the 'on-line' thermodilution technique

Nephrology Dialysis Transplantation, 2003

Background. A method is presented for estimating the confidence limits (CLs), or accuracy, of the... more Background. A method is presented for estimating the confidence limits (CLs), or accuracy, of the arteriovenous fistula flow rate measured at haemodialysis by the 'on-line' thermodilution technique. Methods. This was by derivation of an expression to estimate what variance a set of repeated measures of flow would yield, using values pertaining to a single measure of flow. (Laws of variance were applied to the formula used to calculate flow, to account for its variables' values and measurement errors.) This enabled CLs of a single measure to be estimated.

Research paper thumbnail of Is Gastric Banding Appropriate in Indigenous Or Remote-Dwelling Persons?

Obesity Surgery, 2015

Gastric banding has been promoted as less suitable for indigenous persons or persons who live rem... more Gastric banding has been promoted as less suitable for indigenous persons or persons who live remotely as it requires in person follow-up for band adjustment and may have higher rates of reoperation. This study assessed being an indigenous Australian or living remotely (but not both) on outcomes following gastric banding. Data was prospectively recorded on all 559 patients who underwent gastric banding by one surgeon at one private hospital in Darwin, between February 1998 and August 2014. Forty persons (7 %) were indigenous and 93 (17 %) were remotely living (only 7 were both). At the last assessment (follow-up 37 (SD 31) months), overall percentage of excess weight loss (EWL) was 53 % (30 %), the percentage of total weight loss (TWL) was 23 (13), and 389 (70 %) achieved >50 % EWL. Seventy-two percent (43/60) ceased all diabetic medications. Ninety-two (17 %) came to reoperation. There was little difference between the indigenous and non-indigenous metropolitan-living groups, or between the remote and metropolitan non-indigenous groups in %EWL, %TWL, the proportion who achieved more than 50 % EWL, the time to achieve the goal weight, or cessation of diabetes medication. Similarly, there was little difference in the time to band removal or replacement. No person was directly compromised at band removal/replacement by delay due to dwelling remotely. In these select persons who underwent gastric banding in the private sector only, outcomes of weight loss and revisional surgery were acceptable and comparable between indigenous and non-indigenous metropolitan-dwelling persons as well as between remote and metropolitan-dwelling non-indigenous persons.

Research paper thumbnail of Risks to feet in the top end: Outcomes of diabetic foot complications

Australian and New Zealand Journal of Surgery, Apr 1, 2002

Research paper thumbnail of Flipped out of control: single-vehicle rollover accidents in the Northern Territory

The Medical journal of Australia, Jan 18, 2002

To study the incidence of and factors associated with single-vehicle rollover (SVRO) accidents in... more To study the incidence of and factors associated with single-vehicle rollover (SVRO) accidents in the "Top End" of the Northern Territory (NT); to identify factors associated with major injury and death from SVRO accidents. Retrospective analysis of records from the NT Department of Transport and Works' police database, Royal Darwin Hospital's trauma database, coroner's records, and case notes from public hospitals in the Top End. All patients involved in SVRO accidents in the Top End between 1 January 1996 and 31 December 1997 whose accident was documented by the police, who attended a public hospital, or who died. Types and incidence of all accidents; details of the accident scene, vehicle features, and population groups associated with SVRO accidents; factors associated with major injury and death. SVROs accounted for 30% of all accidents and 29% of all injuries and deaths (441 people) in the whole of the NT over the study period. Some of the factors associa...

Research paper thumbnail of Confidence limits of arteriovenous fistula flow rate measured by the 'on-line' thermodilution technique

Nephrology Dialysis Transplantation, 2003

Background. A method is presented for estimating the confidence limits (CLs), or accuracy, of the... more Background. A method is presented for estimating the confidence limits (CLs), or accuracy, of the arteriovenous fistula flow rate measured at haemodialysis by the 'on-line' thermodilution technique. Methods. This was by derivation of an expression to estimate what variance a set of repeated measures of flow would yield, using values pertaining to a single measure of flow. (Laws of variance were applied to the formula used to calculate flow, to account for its variables' values and measurement errors.) This enabled CLs of a single measure to be estimated.

Research paper thumbnail of Impact of a multidisciplinary team approach upon patency rates of arteriovenous fistulae

Nephrology, 2002

SUMMARY: A team approach to fistula surgery, with a weekly ward round and elective fistula list, ... more SUMMARY: A team approach to fistula surgery, with a weekly ward round and elective fistula list, was introduced at the Royal Darwin Hospital in April 1999. This study has evaluated the impact of this team approach and assessed factors influencing fistula ...

Research paper thumbnail of Emergency neurosurgery by general surgeons at a remote major hospital

ANZ Journal of Surgery, 2005

Background: Due to the geographical remoteness of Darwin, which has no resident neurosurgeon, eme... more Background: Due to the geographical remoteness of Darwin, which has no resident neurosurgeon, emergency transfer of patients for neurosurgery is usually impractical. In Darwin emergency neurosurgery must be undertaken by general surgeons. Methods: Data from the operating theatre, Emergency Department and Intensive Care Unit were prospectively recorded on all patients who underwent an emergency neurosurgical procedure between January 1992 and June 2004. Outcomes were assessed by retrospective case note review. Results: Three hundred and five neurosurgical procedures were performed upon 258 patients (average 26.5 procedures per year), including 130 craniotomies, 88 burr holes, 3 posterior fossa craniotomies, 2 decompressive frontal lobectomies, 4 decompressive craniectomies, 25 elevations of fracture and 33 ventricular drains only. Assault/domestic incident (31%) was a more common aetiology than motor vehicle accidents (29%). Outcome was best for extradural haematoma (82% good/moderate) and chronic subdural haematoma (84% good/moderate). In contrast, 44% with acute subdural haematoma and 77% with intracerebral haematoma died. Irrespective of type of bleed, Glasgow Coma Scale (GCS) score at presentation was a reliable predictor of outcome following surgery (61% correlation): 60% with GCS less than 9 died whereas 79% with GCS over 11 had a good recovery. Acute Physiology And Chronic Health Evaluation, version 2 and Simplified Acute Physiology Score, version 2 scores were also independent predictors of outcome. Time from presentation to operation for extradural haematoma and acute subdural haematoma was prolonged (more than 4 h) in 48% and was associated with worse outcome ( P = 0.0001). Neither extremes of age nor the particular surgeon performing the operation affected outcome. Conclusions: General surgeons undertake a substantial number of procedures across a broad spectrum of emergency neurosurgery in Darwin. Outcomes following surgery appear acceptable.

Research paper thumbnail of Evaluation of amylase and lipase in the diagnosis of acute pancreatitis

ANZ Journal of Surgery, 2001

The diagnosis of acute pancreatitis relies heavily on a raised amylase. Methods: In the present s... more The diagnosis of acute pancreatitis relies heavily on a raised amylase. Methods: In the present study patients were prospectively categorized, without knowledge of pancreatic enzyme levels, into acute pancreatitis (AP; n = 51), disease controls (n = 35), indeterminate as to pancreatitis (n = 189) or exclusions (non-pancreatitis diseases where amylase may be elevated; n = 53). Results: Enzyme levels were analysed by receiver operator characteristics (ROC) curves, with specificity > 80%. Day 1 serum lipase gave the greatest diagnostic accuracy (area under ROC curve = 0.128; P = 0.041 vs serum amylase). At the calculated diagnostic threshold of 208 U/L, lipase gave a sensitivity of 67% and a specificity of 97%. Other diagnostic thresholds (day 1) were: serum total amylase, 176 U/L (ROC 0.104, sensitivity 45%, specificity 97%), urinary total amylase, 550 U/L (ROC 0.108, sensitivity 62%, specificity 97%) and serum pancreatic isoamylase, 41 U/L (ROC 0.107, sensitivity 63%, specificity 85%). At delayed diagnosis (3 days) no enzyme was superior to lipase. The combination of lipase and amylase did not increase diagnostic accuracy. Conclusion: Serum lipase is recommended for diagnosis of AP, both early and late in the disease. Although highly specific when elevated, all pancreatic enzymes have low sensitivity for diagnosis.

Research paper thumbnail of Risks to feet in the top end: Outcomes of diabetic foot complications

ANZ Journal of Surgery, 2002

Research paper thumbnail of Prediction of failure of native arteriovenous fistulas using 'on-line' fistula flow measurements

Nephrology, Jan 1, 2005

Background: Measurement of blood flow within native arteriovenous fistula during haemodialysis i... more Background: Measurement of blood flow within native arteriovenous fistula during haemodialysis is recommended to detect incipient fistula failure. In the present study the value of such flow measurements was assessed in a group of patients on maintenance haemodialysis, with access via native arteriovenous fistulas.Methods: Flow was measured using the ‘on-line’ thermodilution technique, on three separate occasions, and correlated with subsequent fistula failure within 6 months.Results: Of the 53 patients studied, there were six failures (three thromboses and three inadequate dialysis filtration rates). Flow rates in patients who progressed to fistula failure were significantly less than flow rates in patients whose fistulas did not fail (U = 13.0, P < 0.0003). Failure was no more common in one type of fistula than another (type fistula: F = 0.29, P = 0.88; flow predicting failure: F = 7.22, P = 0.010). Receiver operating characteristic (ROC) curve analyses confirmed flow measurement to be a useful predictor of fistula failure (area under ROC curve 0.91). The optimal threshold of 576 mL/min flow gave a sensitivity of 89% and a specificity of 81%. Measurement of access resistance was less useful in predicting failure (area under ROC curve 0.87). Measurement of fall in flow from the previous measurement was of no use (area under ROC curve 0.535).Conclusion: On-line thermodilution measurement of flow within established native arteriovenous fistula is useful in surveillance and early prediction of fistula failure. Fistula flow <576 mL/min may indicate incipient native fistula failure, and should prompt further investigation.

Research paper thumbnail of Confidence limits of arteriovenous fistula flow rate measured by the 'on-line' thermodilution technique

Nephrology Dialysis Transplantation, 2003

Background. A method is presented for estimating the confidence limits (CLs), or accuracy, of the... more Background. A method is presented for estimating the confidence limits (CLs), or accuracy, of the arteriovenous fistula flow rate measured at haemodialysis by the 'on-line' thermodilution technique. Methods. This was by derivation of an expression to estimate what variance a set of repeated measures of flow would yield, using values pertaining to a single measure of flow. (Laws of variance were applied to the formula used to calculate flow, to account for its variables' values and measurement errors.) This enabled CLs of a single measure to be estimated.

Research paper thumbnail of Is Gastric Banding Appropriate in Indigenous Or Remote-Dwelling Persons?

Obesity Surgery, 2015

Gastric banding has been promoted as less suitable for indigenous persons or persons who live rem... more Gastric banding has been promoted as less suitable for indigenous persons or persons who live remotely as it requires in person follow-up for band adjustment and may have higher rates of reoperation. This study assessed being an indigenous Australian or living remotely (but not both) on outcomes following gastric banding. Data was prospectively recorded on all 559 patients who underwent gastric banding by one surgeon at one private hospital in Darwin, between February 1998 and August 2014. Forty persons (7 %) were indigenous and 93 (17 %) were remotely living (only 7 were both). At the last assessment (follow-up 37 (SD 31) months), overall percentage of excess weight loss (EWL) was 53 % (30 %), the percentage of total weight loss (TWL) was 23 (13), and 389 (70 %) achieved &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt;50 % EWL. Seventy-two percent (43/60) ceased all diabetic medications. Ninety-two (17 %) came to reoperation. There was little difference between the indigenous and non-indigenous metropolitan-living groups, or between the remote and metropolitan non-indigenous groups in %EWL, %TWL, the proportion who achieved more than 50 % EWL, the time to achieve the goal weight, or cessation of diabetes medication. Similarly, there was little difference in the time to band removal or replacement. No person was directly compromised at band removal/replacement by delay due to dwelling remotely. In these select persons who underwent gastric banding in the private sector only, outcomes of weight loss and revisional surgery were acceptable and comparable between indigenous and non-indigenous metropolitan-dwelling persons as well as between remote and metropolitan-dwelling non-indigenous persons.

Research paper thumbnail of Risks to feet in the top end: Outcomes of diabetic foot complications

Australian and New Zealand Journal of Surgery, Apr 1, 2002

Research paper thumbnail of Flipped out of control: single-vehicle rollover accidents in the Northern Territory

The Medical journal of Australia, Jan 18, 2002

To study the incidence of and factors associated with single-vehicle rollover (SVRO) accidents in... more To study the incidence of and factors associated with single-vehicle rollover (SVRO) accidents in the "Top End" of the Northern Territory (NT); to identify factors associated with major injury and death from SVRO accidents. Retrospective analysis of records from the NT Department of Transport and Works' police database, Royal Darwin Hospital's trauma database, coroner's records, and case notes from public hospitals in the Top End. All patients involved in SVRO accidents in the Top End between 1 January 1996 and 31 December 1997 whose accident was documented by the police, who attended a public hospital, or who died. Types and incidence of all accidents; details of the accident scene, vehicle features, and population groups associated with SVRO accidents; factors associated with major injury and death. SVROs accounted for 30% of all accidents and 29% of all injuries and deaths (441 people) in the whole of the NT over the study period. Some of the factors associa...

Research paper thumbnail of Confidence limits of arteriovenous fistula flow rate measured by the 'on-line' thermodilution technique

Nephrology Dialysis Transplantation, 2003

Background. A method is presented for estimating the confidence limits (CLs), or accuracy, of the... more Background. A method is presented for estimating the confidence limits (CLs), or accuracy, of the arteriovenous fistula flow rate measured at haemodialysis by the 'on-line' thermodilution technique. Methods. This was by derivation of an expression to estimate what variance a set of repeated measures of flow would yield, using values pertaining to a single measure of flow. (Laws of variance were applied to the formula used to calculate flow, to account for its variables' values and measurement errors.) This enabled CLs of a single measure to be estimated.

Research paper thumbnail of Impact of a multidisciplinary team approach upon patency rates of arteriovenous fistulae

Nephrology, 2002

SUMMARY: A team approach to fistula surgery, with a weekly ward round and elective fistula list, ... more SUMMARY: A team approach to fistula surgery, with a weekly ward round and elective fistula list, was introduced at the Royal Darwin Hospital in April 1999. This study has evaluated the impact of this team approach and assessed factors influencing fistula ...

Research paper thumbnail of Emergency neurosurgery by general surgeons at a remote major hospital

ANZ Journal of Surgery, 2005

Background: Due to the geographical remoteness of Darwin, which has no resident neurosurgeon, eme... more Background: Due to the geographical remoteness of Darwin, which has no resident neurosurgeon, emergency transfer of patients for neurosurgery is usually impractical. In Darwin emergency neurosurgery must be undertaken by general surgeons. Methods: Data from the operating theatre, Emergency Department and Intensive Care Unit were prospectively recorded on all patients who underwent an emergency neurosurgical procedure between January 1992 and June 2004. Outcomes were assessed by retrospective case note review. Results: Three hundred and five neurosurgical procedures were performed upon 258 patients (average 26.5 procedures per year), including 130 craniotomies, 88 burr holes, 3 posterior fossa craniotomies, 2 decompressive frontal lobectomies, 4 decompressive craniectomies, 25 elevations of fracture and 33 ventricular drains only. Assault/domestic incident (31%) was a more common aetiology than motor vehicle accidents (29%). Outcome was best for extradural haematoma (82% good/moderate) and chronic subdural haematoma (84% good/moderate). In contrast, 44% with acute subdural haematoma and 77% with intracerebral haematoma died. Irrespective of type of bleed, Glasgow Coma Scale (GCS) score at presentation was a reliable predictor of outcome following surgery (61% correlation): 60% with GCS less than 9 died whereas 79% with GCS over 11 had a good recovery. Acute Physiology And Chronic Health Evaluation, version 2 and Simplified Acute Physiology Score, version 2 scores were also independent predictors of outcome. Time from presentation to operation for extradural haematoma and acute subdural haematoma was prolonged (more than 4 h) in 48% and was associated with worse outcome ( P = 0.0001). Neither extremes of age nor the particular surgeon performing the operation affected outcome. Conclusions: General surgeons undertake a substantial number of procedures across a broad spectrum of emergency neurosurgery in Darwin. Outcomes following surgery appear acceptable.

Research paper thumbnail of Evaluation of amylase and lipase in the diagnosis of acute pancreatitis

ANZ Journal of Surgery, 2001

The diagnosis of acute pancreatitis relies heavily on a raised amylase. Methods: In the present s... more The diagnosis of acute pancreatitis relies heavily on a raised amylase. Methods: In the present study patients were prospectively categorized, without knowledge of pancreatic enzyme levels, into acute pancreatitis (AP; n = 51), disease controls (n = 35), indeterminate as to pancreatitis (n = 189) or exclusions (non-pancreatitis diseases where amylase may be elevated; n = 53). Results: Enzyme levels were analysed by receiver operator characteristics (ROC) curves, with specificity > 80%. Day 1 serum lipase gave the greatest diagnostic accuracy (area under ROC curve = 0.128; P = 0.041 vs serum amylase). At the calculated diagnostic threshold of 208 U/L, lipase gave a sensitivity of 67% and a specificity of 97%. Other diagnostic thresholds (day 1) were: serum total amylase, 176 U/L (ROC 0.104, sensitivity 45%, specificity 97%), urinary total amylase, 550 U/L (ROC 0.108, sensitivity 62%, specificity 97%) and serum pancreatic isoamylase, 41 U/L (ROC 0.107, sensitivity 63%, specificity 85%). At delayed diagnosis (3 days) no enzyme was superior to lipase. The combination of lipase and amylase did not increase diagnostic accuracy. Conclusion: Serum lipase is recommended for diagnosis of AP, both early and late in the disease. Although highly specific when elevated, all pancreatic enzymes have low sensitivity for diagnosis.

Research paper thumbnail of Risks to feet in the top end: Outcomes of diabetic foot complications

ANZ Journal of Surgery, 2002

Research paper thumbnail of Prediction of failure of native arteriovenous fistulas using 'on-line' fistula flow measurements

Nephrology, Jan 1, 2005

Background: Measurement of blood flow within native arteriovenous fistula during haemodialysis i... more Background: Measurement of blood flow within native arteriovenous fistula during haemodialysis is recommended to detect incipient fistula failure. In the present study the value of such flow measurements was assessed in a group of patients on maintenance haemodialysis, with access via native arteriovenous fistulas.Methods: Flow was measured using the ‘on-line’ thermodilution technique, on three separate occasions, and correlated with subsequent fistula failure within 6 months.Results: Of the 53 patients studied, there were six failures (three thromboses and three inadequate dialysis filtration rates). Flow rates in patients who progressed to fistula failure were significantly less than flow rates in patients whose fistulas did not fail (U = 13.0, P < 0.0003). Failure was no more common in one type of fistula than another (type fistula: F = 0.29, P = 0.88; flow predicting failure: F = 7.22, P = 0.010). Receiver operating characteristic (ROC) curve analyses confirmed flow measurement to be a useful predictor of fistula failure (area under ROC curve 0.91). The optimal threshold of 576 mL/min flow gave a sensitivity of 89% and a specificity of 81%. Measurement of access resistance was less useful in predicting failure (area under ROC curve 0.87). Measurement of fall in flow from the previous measurement was of no use (area under ROC curve 0.535).Conclusion: On-line thermodilution measurement of flow within established native arteriovenous fistula is useful in surveillance and early prediction of fistula failure. Fistula flow <576 mL/min may indicate incipient native fistula failure, and should prompt further investigation.