27th July 2018, Volume 131 Number 1479

Closing the loop: post-operative dual antiplatelet therapy following coronary artery bypass grafting

Josephine HY Mak,1 Sinthuri Raveendran,2 Rory J Kelleher,3 Paul Conaglen,1 Zaw Lin,1 Nand Kejriwal,1 Nick Odom,1 Grant Parkinson,1 David J McCormack,1,4 Adam El-Gamel1,4

1Waikato Cardiothoracic Unit, Waikato Hospital, Hamilton; 2King’s College London, London, England; 3Queen’s University, Belfast, Northern Ireland; 4Department of Surgery, The University of Auckland, Auckland.


Dual antiplatelet therapy (DAPT) improves outcomes following coronary artery bypass grafting (CABG). Recent guidelines stipulate that DAPT should be continued for one year post-operatively in those presenting with ACS (Level 1) and considered in those with stable ischaemic heart disease (Level 2b). An audit previously conducted at a single centre showed 17 different regimens of antiplatelet prescribing post-CABG with no clear pattern. Following this, new departmental guidelines were established. Registrars checked discharge summaries for DAPT instructions. CABG patients received DAPT cards highlighting their indication for DAPT to other healthcare professionals. We present a closed-loop audit to assess for improvement in our practice.


A retrospective analysis was conducted. We analysed discharge summaries of those patients discharged post-CABG in the three months of October to December 2017. The type and duration of antiplatelet regimen in each discharge summary was recorded. Patients with contraindications for DAPT were excluded.


Seventy-one patients were discharged post CABG in the specified three months. Eight patients were excluded as they received anticoagulation. DAPT was thus indicated in 63 patients. 93.7% (n=59) of these patients had an appropriate dual antiplatelet regime documented at discharge.


We demonstrate an improvement in post-operative DAPT prescribing and documentation after our quality improvement initiative. Future directions include auditing whether cardiologists and general practitioners are continuing to prescribe the DAPT in the community and whether patients are taking their medications as prescribed.

Factors associated with the prescription of antipsychotic medication in secure dementia units in the Waikato

Wang D,1 Burton J,2 Ma’u E2

1University of Otago, Dunedin; 2Mental Health Services for Older People, Waikato District Health Board, Hamilton.


Behavioural and psychological symptoms of dementia (BPSD) will affect ~90% of people with dementia at some point in the disease process. Antipsychotic or sedative medications have been a popular choice for first-line management of BPSD, but clinical trials suggest the benefit of antipsychotics, at best, is small.1 Furthermore, long-term use of antipsychotic medication is associated with increased morbidity and mortality.2 The aim of this study was to determine the proportion and characteristics of antipsychotic and sedative use in dementia patients resident in secure dementia units in the Waikato.


The medication chart and residential care files of 280 residents from 14 secure dementia units in the Waikato were reviewed to determine the prevalence of antipsychotic and sedative use, and the factors associated with their prescription.


Antipsychotic medications were prescribed to 140 (50%) residents, with a mean duration of 394 days since the medication was last prescribed. Being prescribed an antipsychotic was associated with male gender (57.1% vs 44.1%, p=.031), being in psychogeriatric level care (63.3% vs 42.9%, p=.002), and having at least one incident form in the preceding six months (60.5% vs 46.4%, p=.039). Following regression analysis, only level of care (p=.007) and not age (p=.600), gender (p=.163) or incident forms (p=.111) predicted antipsychotic prescription, with those in psychogeriatric care 2.04 (95% CI 1.14–3.63) times as likely to be on an antipsychotic compared to those in dementia units.


The prevalence of antipsychotic medication prescribing in secure dementia units is high and increases with higher levels of care. Duration since an antipsychotic prescription was last altered suggests these medications are not being reviewed in line with best practice guidelines.


  1. Reus V, Foctmann L, Eyler E, Hilty M, Horvitz-Lennon M, Jibson M, et al. The American Psychiatric Association Practice Guideline on the Use of Antipsychotics to Treat Agitation or Psychosis in Patients with Dementia. Am J Psychiatry 2016; 173(5):543–46.
  2. Maust D, Kim H, Seyfried L, Chiang C, Kavanagh J, Schneider L, et al. Antipsychotics, other psychotropics, and the risk of death in patients with dementia: number needed to harm. JAMA Psychiatry 2015; 72(5):438–45.

Early discharge from intensive care after cardiac surgery is feasible with an adequate fast track, stepdown unit: Waikato experience

Damian Gimpel,1 Satya Shanbhag,1 Tushar Srivastava,3 Melanie MacLeod,4 Paul Conaglen,1 Nand Kerjiwal,1 Nicholas Odom,1 Zaw Lin,1 David J McCormack,1,2 A El-Gamel1,2

1Waikato Cardiothoracic Unit, Waikato Hospital, Hamilton; 2Faculty of Medical and Health Sciences, The University of Auckland, Auckland; 3School of Medicine, The University of Auckland, Auckland; 4ERU (Enhanced Recovery Unit) Nurse Specialist in charge, Waikato Hospital, Hamilton.


Enhanced recovery programmes within cardiothoracic surgery are a well-described benefit to patient post-operative outcomes. We describe our Australasian unit’s experience of a day 0 discharge enhanced recovery unit from the intensive care department.


Retrospective study from July 2014 till November 2017 with 1,804 patients undergoing cardiac surgery. The primary end point was non-inferiority in 30-day mortality in the day 0 cohort when compared to >1 day discharge from ICU cohort. The secondary outcomes were non-inferiority in 30-day morbidity in the day 0 cohort.


One hundred and sixty-three patients were discharge to the ERU day 0. Mean number of hours spent in ICU for day 0 cohort was 7.1 (+/-1.1). Mean Age 62.52 (+/-11.25), M:F 3.03:1. Patients were more likely to be discharged day 0 if they had a lower Euroscore 1.58 (+/1.67), lower preoperative creatinine 88.48 (+/-27.2), determined non-critical and required less PRBC during ICU stay. Those admitted to the ERU on day 0 post-operatively were more likely to be discharged with a lower creatinine level, a higher Hb level, discharged directly to home and have less readmissions per 30 days (p<0.05).


The utilisation of an enhanced recovery unit in appropriately selected patients is not detrimental to patient care. It enhances the efficiency of a cardiac ICU and decreases costs associated with ICU stay. There is also an ability to utilise pre-operative risk stratification in order to highlight those patients likely to be discharged on day 0 from ICU in order to further enhance the efficiency of a cardiac ICU and hospital management planning.

The pain buster study: Low volume local anaesthetic infusion via an elastometric pump for analgesia following laparotomy

PI: Dr Kelly Byrne; Research assistants: Jono Termaat, Gay Mans, Margaret He; Summer Student: Samuel McCabe

Anaesthetic Research Department, Waikato Hospital, Hamilton.

This study investigated the benefit of low-volume infusion of local anaesthetic into rectus sheath using an elasto-metric pump following midline laparotomy. This device has advantages of being portable as well as needing less nursing input in the ward setting.

Inclusion criteria were patients aged 18–85 having mid-line laparotomies with the ability to consent to the trial and be available for follow up, and no contraindications to the placement of the catheters or infusion of local anaesthetic. All patients received an initial bolus of 40ml of 0.2% Ropivicaine at time of catheter placement. The elastometric pump was connected post-operatively and the patients were allocated to one of three groups: Normal Saline, 0.2% Ropivicaine or 0.5% Ropivicaine. The contents were drawn up by the anaesthetic technician outside of theatre so all staff involved in patient care were blinded to treatment allocation. To show a 30% reduction in pain scores or opiate use, it was calculated that we needed to recruit 120 patients, 40 in each group. Due to slow recruitment the study was truncated at 110 patients.

The primary end point was average pain score and opiate use for the four days following surgery. Secondary end-points were patient rating of analgesia, patient satisfaction and measures of functional recovery.

The patients in the treatment groups had lower pain scores at rest and on movement, with the difference being larger on movement. These differences were significant on days 1 and 2 but not on days 3 and 4. There was no statistically significant difference in opiate requirement for the duration of the study. No differences seen in functional measures such as time to mobilisation, oral intake or return of bowel function.

The elastometric infusion device seems to show a modest benefit in reducing pain scores for people having laparotomies. There was no additional benefit to using 0.5% Ropivicaine compared to 0.2% Ropivicaine.

EuroSCORE II cardiac surgical risk scoring system—the Waikato experience

Navneet Singh, Damian Gimpel, David J McCormack, Adam El Gamel

Waikato Hospital, Hamilton.

EuroSCORE II is a well-established cardiac surgery risk scoring tool. This risk stratification system was derived from a predominantly international patient cohort. No calibration analysis of this operative risk model has been undertaken for New Zealand cardiac surgery patients. We aim to assess the efficacy of EuroSCORE II to the Waikato population.


A retrospective study was carried out to include patients undergoing cardiac surgery at the Waikato Cardiothoracic Unit from September 2014 to September 2017. Patients received either isolated first-time coronary artery bypass grafting (CABG), isolated valve surgery, isolated aortic surgery or a combination of these procedures. Patient demographic information and preoperative medical risk factors were obtained from review of patient records. The primary outcome was the correlation of predicted EuroSCORE II risk scores for 30-day mortality in cardiac surgery patients compared with observed mortality events.


One thousand six hundred and sixty-six cardiac surgery patients were included during the study period. Nine hundred and thirty-three patients underwent isolated CABG, 384 underwent isolated valve surgery, 48 received isolated aortic surgery and 301 received combination procedures. Thirty-day mortality events in each of these groups was 7, 4, 2 and 13 deaths respectively. Receiver operating characteristic curve analysis demonstrated the area under the curve (representing average predictive sensitivity and specificity) of EuroSCORE II in each of these groups as 93.4% (95% confidence interval: 91.6–94.9), 66.3% (95% confidence interval: 61.3–71.0), 37.2% (95% confidence interval: 23.9–52.2) and 74.8% (95% confidence interval: 69.5–79.6) respectively.


EuroSCORE II showed a strong predictive ability for isolated first-time CABG 30-day mortality in a Waikato patient cohort. However, EuroSCORE II performed poorly across non-coronary or combination cardiac surgical procedures. There is an importance to adapt this internationally-derived risk scoring system to our local patient cohort for non-coronary and combination surgery.

Measuring the change in interstitial glucose concentration after feeding in the first five days after birth

Weston PJ,1 Harris DL,1 Harding JE2

1Waikato Hospital, Hamilton; 2Liggins Institute, University of Auckland, Auckland.


Continuous interstitial glucose monitoring may present an opportunity to explore changes in tissue glucose delivery after feeding in newborns. However, suitable metrics are needed to quantify these changes, and to assess factors that may influence them.


Data from the Sugar Babies Study were reviewed and included in this analysis if 90–180min of interstitial glucose concentrations were available from the start of a feeding in the first five days after birth. Interstitial glucose concentration metrics assessed were: maximum deviation from baseline (MD), area under the curve per hour (AUC) and time to peak (TTP) for those feedings with a peak concentration, which was a turning point. Metrics were developed using Stata version 14.2.


Data were available for 4,014 feedings in 367 babies with mean gestation 37.6 weeks (range 34.9–42.7 weeks). Both MD and AUC were positive (mean (95% confidence interval): MD 0.12mmol/l (0.10, 0.14), p<0.001, AUC: 0.06mmol.hr/L (0.05, 0.07), p<0.001). TTP was available for 46% of feedings and occurred at (median, range) 80 minutes (0 to 175) after the beginning of the feed.


Changes in interstitial glucose concentrations after feeding in the first five days can be identified and quantified. These metrics may be useful in future analyses to determine factors that influence glucose responses to feeding and other interventions in newborn babies.

Quality of life after prostate cancer treatment

Ross Lawrenson, Tania Blackmore

University of Waikato, Hamilton.

Prostate cancer is the most commonly diagnosed male cancer in New Zealand, and 2.7% of men in general practice over age 40 have had a previous prostate cancer diagnosis. The side effects of prostate cancer treatment are well recognised. We were interested in the supportive care needs of men who had been diagnosed with prostate cancer two years after diagnosis. One hundred and ninety-six men who were diagnosed in 2014/2015 were sent a postal survey designed to capture post-treatment information such as level of continuing GP involvement and quality of life using the Extended Prostate Cancer Index (EPIC26) and EQ-ED-5L Quality of Life tools. One hundred and thirty-two men responded to the follow-up survey.

The EPIC26 showed that for most men, quality of life following prostate cancer appeared to be good, with only 8 (6.0%) and 7 men (5.0%) reporting moderate or big problems with overall urinary and bowel function respectively. Erectile function was the most reported ongoing symptom, with 46 men (35.0%) indicating that sexual function was a moderate to big problem. The EQ-5D-5L recorded that 28 men (21.2%) had some problems with anxiety or depression, although when asked if they wanted to see a counsellor or psychologist, 120 men (90.9%) responded that they did not want to seek psychological support. Ninety-six (72.7%) men had seen their GP in the previous three months, but 59 (44.7%) considered that their GP was not involved in their ongoing prostate cancer management.

These data suggest that while many men reported relatively few problems and a return to life as normal, there is still some ongoing need for support. We believe GPs could be more involved in the ongoing management of men with prostate cancer.

The role of the FitAB toxin-antitoxin system in the maintenance of the carrier population of Neisseria gonorrhoeae

Hicks JL, Arcus VL

School of Science, University of Waikato, Hamilton.

Gonorrhoea is a sexually transmitted infection caused by the bacteria Neisseria gonorrhoeae. The bacterium adheres to and invades epithelial cells lining the urogenital tract, then traffics across the epithelium and exits into the sub-epithelial layer where it initiates infection. The success of gonorrhoea is in part due to a population of carriers who harbour the bacteria but show no symptoms of disease, yet can still transmit the bacteria to other humans via sexual contact. The carrier population of bacteria are hypothesised to persist in epithelial cells, remaining invisible to surveillance by the immune system. The mechanism by which it is able to persist within epithelial cells is unknown. Toxin-antitoxin systems have been hypothesised to play a role in the persistence of tuberculosis and other bacteria.1 A toxin-antitoxin system termed FitAB (belonging to the VapBC toxin-antitoxin family2) from N. gonorrhoeae is involved in trafficking of the bacteria and replication within epithelial cells.

We have previously shown that VapC, the toxic component of the VapBC system in Mycobacterium smegmatis regulates metabolism by cleaving at specific sites in mRNA transcripts involved in glycerol uptake and metabolism, to regulate and ‘fine tune’ growth of the organism.3 Characterisation of the cellular target of FitB (the toxic component of the FitAB system) would provide a better understanding as to the mechanisms of persistence of this bacterial pathogen. Using the structure of FitAB4 and methods previously established in our lab for the characterisation of VapBC systems from mycobacteria, we are determining the cellular target(s) of FitB, using a combination of pentaprobes and mass spectrometry.5 We can then compare this with RNA-seq data to determine RNA transcripts targeted by FitB.

With emerging multi-drug resistant strains of N. gonorrhoeae treatment options are becoming limited with no alternative treatments in the pipeline. Understanding the molecular mechanism by which the bacterium can slow replication within epithelial cells is crucial for future treatment of the disease.

  1. Sala A, Bordes P Genevaux P. Multiple toxin-antitoxin systems in Mycobacterium tuberculosis. Toxins, 2014; 6(3):1002–1020.
  2. Hopper S, Wilbur JS, Vasquez BL, Larson J, Clary S, Mehr IJ, Seifert HS, So M. Isolation of Neisseria gonorrhoeae Mutants That Show Enhanced Trafficking across Polarized T84 Epithelial Monolayers. Infection and Immunity, 2000; 68(2):896–905. doi: 10.1128/iai.68.2.896-905.2000
  3. McKenzie JL, Robson J, Berney M, Smith TC, Ruthe A, Gardner PP, Arcus VL, Cook GM. A VapBC Toxin-Antitoxin Module Is a Posttranscriptional Regulator of Metabolic Flux in Mycobacteria. Journal of Bacteriology, 2012; 194(9):2189–2204. doi: 10.1128/JB.06790-11
  4. Mattison K, Wilbur JS, So M, Brennan RG. Structure of FitAB from Neisseria gonorrhoeae Bound to DNA Reveals a Tetramer of Toxin-Antitoxin Heterodimers Containing Pin Domains and Ribbon-Helix-Helix Motifs. Journal of Biological Chemistry, 2006; 281(49):37942–37951. doi: 10.1074/jbc.M605198200
  5. McKenzie JL, Duyvestyn JM, Smith T, Bendak K, MacKay J, Cursons R, Arcus VL. Determination of ribonuclease sequence-specificity using Pentaprobes and mass spectrometry. RNA, 2012; 18(6), 1267–1278. doi: 10.1261/rna.031229.111

Pre-operative full blood count markers as a predictor of mortality and morbidity risk after cardiac surgery

Damian Gimpel, Satya Shanbhag, Chey Haran, Paul Conaglen, Nand Kerjiwal, Zaw Lin, Nicholas Odom, David J McCormack, A El-Gamel

Waikato Hospital, Hamilton.


The use of inflammatory markers for risk stratification of post-operative morbidity and mortality in patients with cardiovascular disease may provide benefit in patient selection.1 White cell subtypes such as neutrophils and lymphocytes may be predictive of peri-operative outcomes following cardiac surgery.2 The aim of this study was to investigate the association between preoperative neutrophil to leucocyte ratio (NLR) and lymphocyte to monocyte ratio (LMR) after cardiac surgery. This study planned to add new data from a New Zealand-specific patient cohort to the literature on the effect of LMR and NLR on cardiac surgery patient outcomes.


We present a retrospective study from September 2014 till November 2017 with 1,694 patients undergoing cardiac surgery. Pre-operative haematological profiles were obtained as well as data on pre-operative patient factors and primary end points. The primary end point was 30-day composite of new post-operative atrial fibrillation requiring treatment, new neurological insult, readmission within 30 days and 30-day mortality. The secondary endpoint was long-term all-cause mortality. Pearsons coefficient was utilised to examine the correlation between NLR and LMR and common markers of inflammation (WCC and CRP).


We recorded 356 incidents of new AF requiring treatment, 31 neurological insults, 179 readmissions within 30 days and 46 deaths within 30 days. The aforementioned composite end points are reported versus NLR and LMR (three categories of ratios <2.1, 2.1–3.2 and >3.2). KM curve was analysed against composite end point and the grading of the LM ratio. A high LM ratio trended towards lower composite end points. A ROC curve utilised for the sensitivity and specificity of LM ratio in prediction of composite end point at a cut off of 2.5. An elevated LMR correlated with raised inflammatory markers (WCC and CRP p <0.05) whereas NLR did not.


The interpretation and utilisation of ready available haematological markers can provide inside into the inflammatory status of a patient and highlight those more at risk of peri-operative morbidity and mortality.


  1. Newall N, Grayson AD, Oo AY, et al. Preoperative white blood cell count is independently associated with higher perioperative cardiac enzyme release and increased 1-year mortality after coronary artery bypass grafting. Ann Thorac Surg. 2006; 81(2):583–589.
  2. Giakoumidakis K, Fotos NV, Patelarou A, Theologou S, Argiriou M, Chatziefstratiou AA, Katzilieri C, Brokalaki H. Perioperative neutrophil to lymphocyte ratio as a predictor of poor cardiac surgery patient outcomes. Pragmat Obs Res. 2017 Feb 15; 8:9–14.