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.

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.

Impact of Discontinuation of Antiplatelet Therapy Prior to Isolated Valve and Combined Coronary Artery Bypass Graft and Valve Procedures on Short and Intermediate Term Outcomes.

BACKGROUND: A change in cardiac surgery practice over the past decade has seen an increase in urgent or inpatient referrals for surgery, with antiplatelet therapy often continued up until surgery. This study aims to identify the optimal timing for administration of aspirin to minimise risk of perioperative morbidity and mortality. METHODS: From a prospectively compiled database collected by the Australian and New Zealand Society of Cardiac and Thoracic Surgeons, we identified 8294 patients undertaking combined CABG and valve or isolated valve procedures while discontinuing aspirin. Time points for cessation of antiplatelet therapy were categorised as follows: <2 days, 3-7 days or >7 days preoperatively. We evaluated the association of adverse in-hospital events and intermediate term survival in each time category. RESULTS: Discontinuing aspirin 3 to 7 days from surgery decreased rates of perioperative MI (HR=0.300, p=0.027), return to theatre (HR=0.560, p=0.002) reduced drain output (HR=0.757, p=0.000) and red blood cell and platelet transfusions (HR=0.719, p=0.000 and HR=0.604, p=0.000 respectively) compared to patients continuing aspirin until <2 days from the procedure. Stopping aspirin <2 days from the date of surgery increased risk of perioperative MI (HR=5.919, p=0.000), reoperation for bleeding (HR=2.076, p=0.001), returning to theatre (HR=1.781, p=0.000), ICC drain losses (HR=1.337, p=0.000) and transfusion demands for red blood cells (HR=1.381, p=0.000) and platelets (HR=1.450, p=0.000) when compared to those discontinuing aspirin >7 days from surgery. CONCLUSION: Late discontinuation of aspirin before combined coronary artery bypass graft and valve procedures results in greater rates of bleeding and transfusion requirements. Earlier discontinuation of aspirin results in no benefit in intermediate term survival.

Two Long-Term Mortality Risk Models For Coronary Artery Bypass Graft Surgery Produced in American Populations Validated in an Australian Population.

BACKGROUND: Short-term mortality prediction models have an important role in current cardiac surgical practice. There has been much less attention paid to prediction of long-term outcomes which are probably an equal marker both of surgeon performance and appropriateness of surgical treatment. The aim of this study was to assess the performance of the New York State Cardiac Surgery Reporting System (NYSCSRS) risk model and the Northern New England Cardiovascular Disease Study Group (NNECDSG) risk model on the Australian and New Zealand Society of Cardiac and Thoracic Surgeons (ANZSCTS) patient database. METHODS: The NYSCSRS and the NNECDSG risk models were applied to all patients undergoing isolated coronary artery bypass graft (CABG) surgery that had complete data, were over the age of 18 and had a body mass index between 12 and 78 kg/m2. Predicted mortality was calculated using the published risk model formulae and compared with observed mortality, obtained via linkage with the National Death Index, at four time-points (one, three, five and seven years following surgery). Model discrimination and model calibration were tested at all four time points by determining the C-statistics for receiver operator characteristic (ROC) curves, and studying the Hosmer-Lemeshow chi-square tests, respectively. RESULTS: The NYSCSRS and NNECDSG risk models were applied to 34,961 and 34,998 patients, respectively. The NYSCSRS risk model over-predicted mortality by between 130% and 216% at all four time-points while the NNECDSG risk model under-predicted mortality at one year by 4.3% but over-predicted mortality at three, five and seven years by between 42.5% and 145.7%. The C-statistics obtained fell between 0.779 and 0.741 for the NYSCSRS risk model and between 0.785 and 0.752 for the NNECDSG risk model at all four time-points. Hosmer-Lemeshow chi-square tests returned p-values <0.001 at all four time-points for both risk models. CONCLUSION: The NYSCSRS and NNECDSG risk models do not accurately predict long-term mortality following isolated CABG surgery in the ANZSCTS patient population. The use of either of these risk models is not appropriate in Australia.