Hemostatic Profiles of Patients Who Underwent Transcatheter Versus Surgical Aortic Valve Replacement Versus Percutaneous Coronary Intervention

Guidelines for transcatheter aortic valve replacement (TAVR) antithrombotic prophylaxis are extrapolated predominantly from percutaneous coronary intervention (PCI) data. Here, we examined temporal coagulation changes occurring in the early perioperative period to determine the pathobiologic validity of this supposition. This was a prospective observational study of consecutive patients who underwent transfemoral TAVR (n = 27), PCI (n = 12), or surgical aortic valve replacement (SAVR) requiring cardiopulmonary bypass and cross-clamping (n = 12). Blood samples were taken at 4 time points: T1 (baseline), after general anesthesia or sedation; T2, after heparin administration; T3, at the end of the procedure; and T4, 6 hours after the procedure. The samples were assessed concurrently using standard laboratory coagulation tests and viscoelastic tests of whole blood clotting, including the latest generation thromboelastometry (ROTEM sigma) and thromboelastometry (TEG 6s). Patients in the TAVR cohort were older and a had lower baseline hemoglobin level than patients in the PCI and SAVR cohorts. The baseline platelet function was similar between the TAVR and PCI cohorts and impaired in the SAVR cohort Figure S1. The baseline hemostatic measures were comparable among cohorts. Regarding the per-patient change from baseline, the TAVR cohort showed an overall more prothrombotic state than the other cohorts, with the most marked differences from the SAVR cohort after intraoperative heparin administration and from the PCI cohorts 6 hours after the procedure. In addition, the ROTEM and TEG parameters were well correlated but not interchangeable. In conclusion, patients who underwent TAVR have a more prothrombotic hemostatic profile than PCI and SAVR patients. These findings question the current guidelines that extrapolate antithrombotic regimens from PCI to TAVR settings.

Nursing experiences in antimicrobial optimisation in the intensive care unit: A convergent analysis of a national survey

BACKGROUND

Recent evidence highlights the need for an interdisciplinary approach to antimicrobial stewardship (AMS). Nursing involvement in optimising antimicrobials in the intensive care unit (ICU) remains understudied.

OBJECTIVE

The objective of this study was to explore nurses' perceptions and experiences of antimicrobial optimisation or stewardship in ICUs in Australia.

METHODS

An anonymous web-based survey was deployed nationally in early 2021 through two ICU nursing networks. Associations between survey responses were analysed descriptively and by using nonparametric tests (with statistical significance established at p ≤ 0.05). Free-text survey responses underwent qualitative thematic analysis. Interpretation and reporting of quantitative and qualitative data were integrated.

RESULTS

A total of 226 ICU nurses completed the survey. The majority (197/226; 87%) responded that lack of education limits engagement in AMS. Only 13% (30/226) reported the presence of AMS education and training for nurses in their ICUs. Only about half (108/226; 48%) of the nurses were confident to question prescribers when they considered that the antimicrobial prescribed was unnecessary, with nurses in senior roles more likely to do so than nurses providing bedside care (p < 0.05). Gaps in education (including unfamiliarity with AMS roles), noninclusive antimicrobial discussions, moral distress, and potential workload burden were seen as potential barriers/challenges to engagement.

CONCLUSION

The multifactorial barriers identified that inhibit nurses from performing AMS tasks could be addressed by strengthening interprofessional education at all levels and by applying practical AMS interventions that are inclusive for nursing participation. A purposeful culture change that fosters psychological safety and collaborative practice is paramount to supporting nurses in these roles.

Haematological Trends and Transfusion during Adult Extracorporeal Membrane Oxygenation: A Single Centre Study

The temporal trends in haematological parameters and their associations with blood product transfusion requirements in patients supported with extracorporeal membrane oxygenation (ECMO) are poorly understood. We performed a retrospective data analysis to better understand the behaviour of haematological and coagulation parameters and their associations with transfusion requirements during ECMO.

METHODS

Patient demographics, haematological and coagulation parameters, plasma haemoglobin and fibrinogen concentrations, platelet count, the international normalised ratio (INR), the activated partial thromboplastin time (APTT), and blood product transfusion data from 138 patients who received ECMO in a single high-volume centre were analysed.

RESULTS

Ninety-two patients received venoarterial (VA) ECMO and 46 patients received venovenous (VV) ECMO. The median (IQR) duration of VA, and VV ECMO was 8 (5-13) days and 13 (8-23) days, respectively. There were significant reductions in haemoglobin, the platelet count, and the fibrinogen concentration upon initiation of ECMO. On average, over time, patients on VV ECMO had platelet counts 44 × 109/L higher than those on VA ECMO (p ≤ 0.001). Fibrinogen and APTT did not vary significantly based on the mode of ECMO (p = 0.55 and p = 0.072, respectively). A platelet count < 50 × 109/L or a fibrinogen level < 1.8 g/L was associated with 50% chance of PRBC transfusion, regardless of the ECMO type, and packed red blood cell (PRBC) transfusion was more common with VA ECMO. APTT was predictive of the transfusion requirement, and the decrement in APTT was discriminatory between VVECMO survivors and nonsurvivors.

CONCLUSION

ECMO support is associated with reductions in haemoglobin, platelet count, and fibrinogen. Patients supported with VA ECMO are more likely to receive a PRBC transfusion compared to those on VV ECMO. Thrombocytopaenia, hypofibrinogenaemia, and anticoagulation effect the likelihood of requiring PRBC transfusion. Further research is needed to define optimal blood management during ECMO, including appropriate transfusion triggers and the anticoagulation intensity.

Rib fracture-related morbidity and mortality for older persons in the era of fascial plane blocks: A cohort study

Introduction

Analgesia is key to successful conservative, nonsurgical management of patients admitted to the hospital with multiple rib fractures. Recently, new fascial plane regional anesthesia techniques have become widely available. We hypothesized that since the introduction of these new regional analgesia techniques, for patients over the age of 65 years, the effect of increasing numbers of rib fractures has been mitigated.

Methods

A retrospective study of patients admitted for the management of rib fractures between 2017 and 2020 was performed. Patients not admitted to the hospital, under the age of 65 years, or with chest trauma other than rib fractures were not eligible for inclusion. The primary outcome of interest was mortality. The secondary outcomes were the incidence of pneumonia and intensive care unit admission. Results were reported as the odds ratio and its 95% confidence interval and associated p-value. Statistical significance was set at [Formula: see text] < 0.05.

Results

Overall, 252 patients were included and 142 patients received a regional anesthesia. The mortality rate was 4% (n = 10) with no association between mortality and number of rib fractures ( p = 0.215). Twenty-four patients (9.5%) developed pneumonia during their hospital stay, again with no association with an increasing number of rib fractures. The intensive care unit admission rate was 13.1% (n = 33) and correlated with an increasing number of fractures (odds ratio = 1.15; 95% confidence interval = 1.01 to 1.31; p = 0.038).

Conclusion

Management including liberal utilization of regional anesthesia for at-risk patients appears to mitigate the effect of increasing numbers of rib fractures on the incidence of mortality and pneumonia.

Outcomes of Prolonged ICU Stay for Patients Undergoing Cardiac Surgery in Australia and New Zealand

OBJECTIVE

To determine the effect of intensive care unit (ICU) length of stay (LOS) on hospital mortality and non-home discharge for patients undergoing cardiac surgery over a 16-year period in Australia and New Zealand.

DESIGN

A retrospective, multicenter cohort study covering the period January 1, 2004 to December 31, 2019.

SETTING

One hundred one hospitals in Australia and New Zealand that submitted data to the Australia New Zealand Intensive Care Society Adult Patient Database.

PARTICIPANTS

Adult patients (aged >18) who underwent coronary artery bypass grafting, valve surgery, or combined valve + coronary artery surgery.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

The authors analyzed 252,948 cardiac surgical patients from 101 hospitals, with a median age of 68.3 years (IQR 60-75.5), of whom 74.2% (187,632 of 252,948) were male patients. A U-shaped relationship was observed between ICU LOS and hospital mortality, with significantly elevated mortality at short (<20 hours) and long (>5 days) ICU LOS, which persisted after adjustment for illness severity and across clinically important subgroups (odds ratio for mortality with ICU LOS >5 days = 3.21, 95% CI 2.88-3.58, p < 0.001).

CONCLUSIONS

Prolonged duration of ICU LOS after cardiac surgery is associated with increased hospital mortality in a U-shaped relationship. An ICU LOS >5 days should be considered a meaningful definition for prolonged ICU stay after cardiac surgery.

The impact of reduction in intensity of mechanical ventilation upon venovenous ECMO initiation on radiographically assessed lung edema scores: A retrospective observational study

Background

Patients with severe acute respiratory distress syndrome (ARDS) typically receive ultra-protective ventilation after extracorporeal membrane oxygenation (ECMO) is initiated. While the benefit of ECMO appears to derive from supporting “lung rest”, reductions in the intensity of mechanical ventilation, principally tidal volume limitation, may manifest radiologically. This study evaluated the relative changes in radiographic assessment of lung edema (RALE) score upon venovenous ECMO initiation in patients with severe ARDS.

Methods

Digital chest x-rays (CXR) performed at baseline immediately before initiation of ECMO, and at intervals post (median 1.1, 2.1, and 9.6 days) were reviewed in 39 Adult ARDS patients. One hundred fifty-six digital images were scored by two independent, blinded radiologists according to the RALE (Radiographic Assessment of Lung Edema) scoring criteria. Ventilatory data, ECMO parameters and fluid balance were recorded at corresponding time points. Multivariable analysis was performed analyzing the change in RALE score over time relative to baseline.

Results

The RALE score demonstrated excellent inter-rater agreement in this novel application in an ECMO cohort. Mean RALE scores increased from 28 (22–37) at baseline to 35 (26–42) (p < 0.001) on D1 of ECMO; increasing RALE was associated with higher baseline APACHE III scores [ß value +0.19 (0.08, 0.30) p = 0.001], and greater reductions in tidal volume [ß value −2.08 (−3.07, −1.10) p < 0.001] after ECMO initiation. Duration of mechanical ventilation, and ECMO support did not differ between survivors and non-survivors.

Conclusions

The magnitude of reductions in delivered tidal volumes correlated with increasing RALE scores (radiographic worsening) in ARDS patients receiving ECMO. Implications for patient centered outcomes remain unclear. There is a need to define appropriate ventilator settings on venovenous ECMO, counterbalancing the risks vs. benefits of optimal “lung rest” against potential atelectrauma.

Erector spinae plane versus paravertebral catheter techniques for rib fracture analgesia: A pilot matched cohort study

Background

Numerous regional techniques are available to provide analgesia and reduce complications related to rib fractures. There is a paucity of evidence comparing the efficacy of these techniques. This pilot study aims to assess the efficacy of erector spinae plane block (ESPB) versus paravertebral block (PVB) catheters for rib fracture analgesia.

Methods

Patients who received either an ESPB or PVB catheter for rib fracture analgesia over the study period (April 2017 to September 2020) were eligible for inclusion. Patients were matched based on demographics and injury characteristics. Outcomes of interest included pre and post catheter-insertion numerical pain scores at rest and with movement, and time to rescue analgesia following catheter insertion.

Results

Thirty-four matched patients were included in this study. Pain scores at rest and with movement were significantly reduced in both groups. There were no statistically significant differences in post-block pain scores or time to rescue analgesia between the two groups. Fifteen (88.2%) of those in both groups had a documented subjective improvement in pain, inspiratory effort or cough strength.

Conclusion

This pilot study is the first to show that the recently described ESPB technique provides non-inferior analgesia compared to PVB for the management of rib fractures. Both techniques were effective in reducing pain scores and had similar times to rescue analgesia. This study supports claim that the ESPB is an effective alternative to traditional regional techniques in the management of rib fractures.

Non-home discharge after cardiac surgery in Australia and New Zealand: a cross-sectional study

OBJECTIVE

To determine the proportion of patients surviving their cardiac surgery who experienced non-home discharge (NHD) over a 16-year period in Australia and New Zealand (ANZ).

DESIGN

Retrospective, multicentre, cross-sectional study over the time period 01 January 2004 to 31 December 2019.

SETTING

Adult patients who underwent cardiac surgery from the Australia New Zealand Intensive Care Society Adult Patient Database (APD).

PARTICIPANTS

Adult patients (age 18 and above) who underwent index coronary artery bypass grafting, cardiac valve surgery or combined valve/coronary surgery.

EXPOSURE

The primary exposure variable was the calendar year during the which the index surgery was performed.

OUTCOME

The primary outcome was NHD after the index surgery. NHD included discharge to locations such as nursing home, chronic care facility, rehabilitation and palliative care.

RESULTS

We analysed 252 924 index cardiac surgical admissions from 101 discrete sites with a median age of 68 years (IQR 60-76), of which 74.2% (187 662 out of 252 920) were males. Of these, 4302 (1.7%) patients died in hospital and 213 011 (84.2%) were discharged home, 18 010 (7.1%) were transferred to another hospital and 17 601 (7%) experienced NHD. In Australia, 14 457 (6.4%) of patients progressed to NHD, compared with 3144 (11.7%) in New Zealand. The rate of NHD increased significantly over time (adjusted OR per year=1.06, 95% CI, 1.06 to 1.07, p<0.001). Increasing age, female sex, non-elective surgery, surgery type and Acute Physiology and Chronic Health Evaluation III Score were all associated with significant increase in NHD.

CONCLUSIONS

There was significant increase in NHD after cardiac surgery over time in ANZ. This has significant clinical relevance for informed consent discussions between healthcare providers and patients, and for healthcare services planning.

The Association of Oxygenation, Carbon Dioxide Removal, and Mechanical Ventilation Practices on Survival During Venoarterial Extracorporeal Membrane Oxygenation

Introduction: Oxygenation and carbon dioxide removal during venoarterial extracorporeal membrane oxygenation (VA ECMO) depend on a complex interplay of ECMO blood and gas flows, native lung and cardiac function as well as the mechanical ventilation strategy applied. Objective: To determine the association of oxygenation, carbon dioxide removal, and mechanical ventilation practices with in-hospital mortality in patients who received VA ECMO. Methods: Single center, retrospective cohort study. All consecutive patients who received VA ECMO in a tertiary ECMO referral center over a 5-year period were included. Data on demographics, ECMO and ventilator support details, and blood gas parameters for the duration of ECMO were collected. A multivariable logistic time-series regression model with in-hospital mortality as the primary outcome variable was used to analyse the data with significant factors at the univariate level entered into the multivariable regression model. Results: Overall, 52 patients underwent VA ECMO: 26/52 (50%) survived to hospital discharge. The median PaO2 for the duration of ECMO support was 146 mmHg [IQR 131-188] and PaCO2 was 37.2 mmHg [IQR 35.3, 39.9]. Patients who survived to hospital discharge had a significantly lower median PaO2 (117 [98, 140] vs. 154 [105, 212] mmHg, P = 0.04) and higher median PaCO2 (38.3 [36.1, 41.1] vs. 36.3 [34.5, 37.8] mmHg, p = 0.03). Survivors also had significantly lower median VA ECMO blood flow rate (EBFR, 3.6 [3.3, 4.2] vs. 4.3 [3.8, 5.2] L/min, p = < 0.001) and greater measured minute ventilation (7.04 [5.63, 8.35] vs. 5.32 [4.43, 6.83] L/min, p = 0.01). EBFR, PaO2, PaCO2, and minute ventilation, however, were not independently associated with death in a multivariable analysis. Conclusion: This exploratory analysis in a small group of VA ECMO supported patients demonstrated that hyperoxemia was common during VA ECMO but was not independently associated with increased mortality. Survivors also received lower EBFR and had greater minute ventilation, but this was also not independently associated with survival. These findings highlight that interactions between EBFR, PaO2, and native lung ventilation may be more relevant than their individual association with survival. Further research is indicated to determine the optimal ECMO and ventilator settings on outcomes in VA ECMO.

Skeletal muscle microvascular perfusion responses to cuff occlusion and submaximal exercise assessed by contrast-enhanced ultrasound: The effect of age

Impairments in skeletal muscle microvascular function are frequently reported in patients with various cardiometabolic conditions for which older age is a risk factor. Whether aging per se predisposes the skeletal muscle to microvascular dysfunction is unclear. We used contrast‐enhanced ultrasound (CEU) to compare skeletal muscle microvascular perfusion responses to cuff occlusion and leg exercise between healthy young (n = 12, 26 ± 3 years) and older (n = 12, 68 ± 7 years) adults. Test–retest reliability of CEU perfusion parameters was also assessed. Microvascular perfusion (microvascular volume × flow velocity) of the medial gastrocnemius muscle was measured before and immediately after: (a) 5‐min of thigh‐cuff occlusion, and (b) 5‐min of submaximal intermittent isometric plantar‐flexion exercise (400 N) using CEU. Whole‐leg blood flow was measured using strain‐gauge plethysmography. Repeated measures were obtained with a 15‐min interval, and averaged responses were used for comparisons between age groups. There were no differences in post‐occlusion whole‐leg blood flow and muscle microvascular perfusion between young and older participants (p > .05). Similarly, total whole‐leg blood flow during exercise and post‐exercise peak muscle microvascular perfusion did not differ between groups (p > .05). The overall level of agreement between the test–retest measures of calf muscle perfusion was excellent for measurements taken at rest (intraclass correlation coefficient [ICC] 0.85), and in response to cuff occlusion (ICC 0.89) and exercise (ICC 0.95). Our findings suggest that healthy aging does not affect muscle perfusion responses to cuff‐occlusion and submaximal leg exercise. CEU muscle perfusion parameters measured in response to these provocation tests are highly reproducible in both young and older adults.

Novel chest wall blocks for severe chest wall injuries in older persons: A case series

Patients over the age of 65 years admitted to hospital with more than six rib fractures have a mortality rate as high as 38%. Of the survivors, 34% are likely to be admitted to an aged care facility. High-quality analgesia is paramount to the mitigation of rib fracture–associated morbidity and mortality. We report a series of ten consecutive patients over the age of 65 years with more than eight fractured ribs. All patients were managed with a novel chest wall block. There were no deaths, and only one patient was discharged into an aged care facility.

Development and validation of a tool to appraise guidelines on SARS-CoV-2 infection control strategies in healthcare workers

BACKGROUND

Clinical guidelines on infection control strategies in healthcare workers (HCWs) play an important role in protecting them during the severe acute respiratory syndrome coronavirus 2 pandemic. Poorly constructed guidelines that are incomprehensive and/or ambiguous may compromise HCWs' safety.

OBJECTIVE

The objective of this study was to develop and validate a tool to appraise guidelines on infection control strategies in HCWs based on the guidelines published early in the coronavirus disease 2019 pandemic.

DESIGN, SETTING, AND OUTCOMES

A three-stage, web-based, Delphi consensus-building process among a panel of diverse HCWs and healthcare managers was performed. The tool was validated by appraising 40 international, specialty-specific, and procedure-specific guidelines along with national guidelines from countries with a wide range of gross national income.

RESULTS

Overall consensus (≥75%) was reached at the end of three rounds for all six domains included in the tool. The Delphi panel recommended an ideal infection control guideline should encompass six domains: general characteristics (domain 1), engineering recommendations (domain 2), personal protective equipment (PPE) use (domain 3), and administrative aspects (domain 4-6) of infection control. The appraisal tool performed well across the six domains, and the inter-rater agreement was excellent for the 40 guidelines. All included guidelines performed relatively better in domains 1-3 than in domains 4-6, and this was more evident in guidelines originating from lower income countries.

CONCLUSION

The guideline appraisal tool was robust and easy to use. Engineering recommendations aspects of infection control, administrative measures that promote optimal PPE use, and HCW wellbeing were generally lacking in assessed guidelines. This tool may enable health systems to adopt high-quality HCW infection control guidelines during the severe acute respiratory syndrome coronavirus 2 pandemic and may also provide a framework for future guideline development.

Development and implementation of a clinical information system-based protocol to improve nurse satisfaction of end-of-life care in a single intensive care unit

BACKGROUND

Patients treated in Australian intensive care units (ICUs) have an overall mortality rate of 5.05%. This is due to the critical nature of their disease, the increasing proportion of patients with multiple comorbidities, and advanced age. This has made treating patients during the end of life an integral part of intensive care practice and requires a high quality of care. With the increased use of electronic clinical information systems, a standardised protocol encompassing end-of-life care may provide an efficient method for documentation, communication, and timely delivery of comfort care.

OBJECTIVE

The aim of the study was to determine if an electronic clinical information system-based end-of-life care protocol improved nurses' satisfaction with the practice of end-of-life care for patients in the ICU.

DESIGN

This is a prospective single-centre observational study.

SETTING

The study was carried out at a 20-bed cardiothoracic and general ICU between 2015 and 2017.

PARTICIPANTS

The study participants were ICU nurses.

INTERVENTION

Electronic clinical information-based end-of-life care protocol was used in the study.

OUTCOME

The primary outcome was nurse satisfaction obtained by a survey.

RESULTS

The number of respondents for the before survey and after survey was 58 (29%) and 64 (32%), respectively. There was a significant difference between the before survey and the after survey with regard to feeling comfortable in transitioning from curative treatment (median = 2 [interquartile range {IQR} = 2, 3] vs 3 [IQR = 2, 3], p = 0.03), feeling involved in the decision to move from curative treatment to end-of-life care (median = 2 [IQR = 2, 2] vs 2 [IQR 2, 3], p = 0.049), and feeling religious beliefs/rituals should be respected during the end-of-life process (median = 4 [IQR = 3, 4] vs. 4 [IQR = 4, 4], p = 0.02). There were some practices that had a low satisfaction rate on both the before survey and after survey. However, a high proportion of nurses were satisfied with many of the end-of-life care practices.

CONCLUSION

The nurses were highly satisfied with many aspects of end-of-life care practices in this unit. The use of an electronic clinical information system-based protocol improved nurse satisfaction and perception of quality of end-of-life care practices for three survey questions.

Nasogastric tube placement under sonographic observation: A comparison study of ultrasound and chest radiography in mechanically ventilated patients

BACKGROUND

Nasogastric tube insertion in the intensive care setting is common. Placement verification is required to avoid complications of bronchotracheal misplacement that range from aspiration of infused contents to death from associated causes. The gold standard of practice is chest radiography. Ultrasound is a growing modality and is readily available in most intensive care units.

OBJECTIVE

The objective of this study was to examine the diagnostic accuracy of ultrasound imaging of nasogastric tube placements by nonradiologists compared with chest radiography in mechanically ventilated patients.

METHODS

This is a dual-centre prospective, single-blind study. Correct placement was captured with a hyperechoic ultrasound image of a nasogastric tube in the oesophagus and epigastrium, which was compared with chest radiography. Patient enrolment included general adult intensive care unit admissions who were mechanically ventilated and required a nasogastric tube for either the treatment or monitoring of their illness.

RESULTS

A total of 25 patients were enrolled (15 men, 10 women), and their mean age was 68.1 ± 13.8 years. Outcome measures were the percentage of correctly identified nasogastric tubes in the oesophagus and epigastrium. The sensitivity of oesophagus ultrasound was 88%, and the positive predictive value was 100%. The subxiphoid sensitivity was 64%, and the positive predictive value was 100%. Comparison sensitivity and specificity of oesophagus versus subxiphoid ultrasound was 64% and 33%, respectively. There was a positive predictive value of 88% and a negative predictive value of 11%. The results showed a variance in detection sensitivity in the ultrasound scans of the oesophagus (0.88) and subxiphoid (0.64) (N = 25, p = 0.012).

CONCLUSION

Nasogastric tube placement verification via ultrasound in critically ill mechanically ventilated patients conducted by nonradiologists with minimal training is associated with diagnostic accuracy. These results add to the limited evidence in the current literature; however, they should be considered with awareness that placement in the stomach in this study was detected in 64% of cases, alongside the missed captured evidence of the sonographer's ability to identify misplacement.

Barriers-enablers-ownership approach: a mixed methods analysis of a social intervention to improve surgical antibiotic prescribing in hospitals

OBJECTIVES

To assess an intervention for surgical antibiotic prophylaxis (SAP) improvement within surgical teams focused on addressing barriers and fostering enablers and ownership of guideline compliance.

DESIGN

The Queensland Surgical Antibiotic Prophylaxis (QSAP) study was a multicentre, mixed methods study designed to address barriers and enablers to SAP compliance and facilitate engagement in self-directed audit/feedback and assess the efficacy of the intervention in improving compliance with SAP guidelines. The implementation was assessed using a 24-month interrupted time series design coupled with a qualitative evaluation.

SETTING

The study was undertaken at three hospitals (one regional, two metropolitan) in Australia.

PARTICIPANTS

SAP-prescribing decisions for 1757 patients undergoing general surgical procedures from three health services were included. Six bimonthly time points, pre-implementation and post implementation of the intervention, were measured. Qualitative interviews were performed with 29 clinical team members. SAP improvements varied across site and time periods.

INTERVENTION

QSAP embedded ownership of quality improvement in SAP within surgical teams and used known social influences to address barriers to and enablers of optimal SAP prescribing.

RESULTS

The site that reported senior surgeon engagement showed steady and consistent improvement in prescribing over 24 months (prestudy and poststudy). Multiple factors, including resource issues, influenced engagement and sites/time points where these were present had no improvement in guideline compliance.

CONCLUSIONS

The barriers-enablers-ownership model shows promise in its ability to facilitate prescribing improvements and could be expanded into other areas of antimicrobial stewardship. Senior ownership was a predictor of success (or failure) of the intervention across sites and time periods. The key role of senior leaders in change leadership indicates the critical need to engage other specialties in the stewardship agenda. The influence of contextual factors in limiting engagement clearly identifies issues of resource distributions/inequalities within health systems as limiting antimicrobial optimisation potential.

Evaluation of latest viscoelastic coagulation assays in the transcatheter aortic valve implantation setting

Background

Point of care viscoelastic measures with thromboelastography (TEG; Haemonetics Corporation, Switzerland) and thromboelastometry (ROTEM, Tem Innovations GmbH, Germany) now supersede laboratory assays in the perioperative assessment and management of coagulation. To the best of our knowledge, this sophisticated coagulation assessment has not been performed to characterise thrombotic changes in the transcatheter aortic valve implantation (TAVI) setting, nor have the two latest iteration cartridge-based systems been directly compared in the elective perioperative period.

Methods

Patients undergoing TAVI were prospectively recruited. Samples (n=44) were obtained at four timepoints (postinduction of anaesthesia, postheparin (100 IU/kg), postprotamine (1 mg/100 IU heparin) and 6 hours postoperatively). Each sample was concurrently assessed with standard laboratory tests (prothrombin time/international normalised ratio, activated partial thromboplastin time, thrombin clotting time, platelet count and direct fibrinogen, ROTEMSigma and TEG6s).

Results

Clot strength showed a statistically significant increase postheparin/TAVI deployment. When considering the subgroup of samples taken following the administration heparin, the heparinase channel of the TEG6s did not yield clotting strength results in 55% of samples and clotting time exceeded the upper limit of normal in 70% of samples. It was retrospectively recognised that the arachidonic acid channel of the TEG6s Platelet Mapping Cartridge had been decommissioned prohibiting assessment of aspirin effect.

Conclusions

This study demonstrated a small intraprocedural prothrombotic change of uncertain clinical importance during the transcatheter aortic valve procedure. Further comparison with percutaneous coronary intervention and aortic valve replacement cohorts are needed to assess the merits of current antithrombotic guidelines, which are extrapolated from the PCI setting. The heparin effect was more consistently quantified by ROTEM.

An Experimental Series Investigating the Effects of Hyperinsulinemic Euglycemia on Myocardial Blood Flow Reserve in Healthy Individuals and on Myocardial Perfusion Defect Size following ST-Segment Elevation Myocardial Infarction

BACKGROUND

Incomplete restoration of myocardial blood flow (MBF) is reported in up to 30% of ST-segment elevation myocardial infarction (STEMI) despite prompt mechanical revascularization. Experimental hyperinsulinemic euglycemia (HE) increases MBF reserve (MBFR). If fully exploited, this effect may also improve MBF to ischemic myocardium. Using insulin-dextrose infusions to induce HE, we conducted four experiments to determine (1) how insulin infusion duration, dose, and presence of insulin resistance affect MBFR response; and (2) the effect of an insulin-dextrose infusion given immediately following revascularization of STEMI on myocardial perfusion.

METHODS

The MBFR was determined using myocardial contrast echocardiography. Experiment 1 (insulin duration): 12 participants received an insulin-dextrose or saline infusion for 120 minutes. MBFR was measured at four time intervals during infusion. Experiment 2 (insulin dose): 22 participants received one of three insulin doses (0.5, 1.5, 3.0 mU/kg/minute) for 60 minutes. Baseline and 60-minute MBFRs were determined. Experiment 3 (insulin resistance): five metabolic syndrome and six type 2 diabetes (T2DM) participants received 1.5 mU/kg/minute of insulin-dextrose for 60 minutes. Baseline and 60-minute MBFRs were determined. Experiment 4 (STEMI): following revascularization for STEMI, 20 patients were randomized to receive either 1.5 mU/kg/minute insulin-dextrose infusion for 120 minutes or standard care. Myocardial contrast echocardiography was performed at four time intervals to quantify percentage contrast defect length.

RESULTS

Experiment 1: MBFR increased with time through to 120 minutes in the insulin-dextrose group and did not change in controls. Experiment 2: compared with baseline, MBFR increased in the 1.5 (2.42 ± 0.39 to 3.25 ± 0.77, P = .002), did not change in the 0.5, and decreased in the 3.0 (2.64 ± 0.25 to 2.16 ± 0.33, P = .02) mU/kg/minute groups. Experiment 3: compared with baseline, MBFR increase was only borderline significant in metabolic syndrome and T2DM participants (1.98 ± 0.33 to 2.59 ± 0.45, P = .04, and 1.67 ± 0.35 to 2.14 ± 0.21, P = .05). Experiment 4: baseline percentage contrast defect length was similar in both groups but with insulin decreased with time and was significantly lower than in controls at 60 minutes (2.8 ± 5.7 vs 13.7 ± 10.6, P = .02).

CONCLUSIONS

Presence of T2DM, insulin infusion duration, and dose are important determinants of the MBFR response to HE. When given immediately following revascularization for STEMI, insulin-dextrose reduces perfusion defect size at one hour. Hyperinsulinemic euglycemia may improve MBF following ischemia, but further studies are needed to clarify this.

Risk Factors for Mortality in Patients Undergoing Cardiothoracic Surgery for Infective Endocarditis

BACKGROUND

This study aimed to identify risk factors associated with mortality of patients who undergo cardiac surgery for infective endocarditis.

METHODS

A retrospective review was performed of patients with infective endocarditis who underwent cardiac surgery at a quaternary Australian hospital between 2004 and 2014. Patient data were collected and prospectively analyzed.

RESULTS

In all, 465 patients underwent surgery during the study period, with 30 deaths (6.45%). Factors independently associated with in-hospital mortality were increasing age (odds ratio [OR] 1.04; 95% confidence interval [CI], 1.01 to 1.07; P = .009), active bacterial endocarditis at time of operation (OR 4.91; 95% CI, 1.01 to 23.8; P = .048), preoperative invasive positive pressure ventilation (OR 3.65; 95% CI, 1.18 to 11.27; P = .025), increasing cardiopulmonary bypass time (OR 1.01; 95% CI, 1.006 to 1.014; P < .001), and increasing European System for Cardiac Operative Risk Evaluation score (OR 21.73; 95% CI, 2.12 to 223.11; P < .01).

CONCLUSIONS

The in-hospital mortality of patients with infective endocarditis remains significant, with potential risk factors including increasing age, active bacterial endocarditis, preoperative invasive positive pressure ventilation, increasing cardiopulmonary bypass time, and high European System for Cardiac Operative Risk Evaluation score.

Acute stroke patients not meeting their nutrition requirements: Investigating nutrition within the enriched environment

BACKGROUND & AIMS

Malnutrition is common after stroke. We investigated the impact of environmental enrichment strategies on dietary intake and rates of malnutrition in an acute stroke unit.

METHODS

We performed a before-after study. In standard care, meals were delivered to participants' rooms whilst in the enriched environment, communal meals with assistance were offered and nutritional intake reminders were placed at the patient bedside. Nutrition supplementation was provided to both groups if indicated. Breakfast and lunch meals were directly observed while remaining intake was calculated using food charts. Nutrition requirements were calculated for energy (ratio method), protein (1 g/kg) and proportion of requirements met. Malnutrition was assessed using the Subjective Global Assessment and body weight. ANCOVA adjusting for stroke severity was used to determine between group differences. Stepwise multivariable logistic regression was performed to assess predictors of nutritional outcomes, adjusting for intervention group, demographic, clinical and baseline nutritional factors.

RESULTS

Neither standard care (n = 30, age 76.0yrs ± SD12.8) nor enriched environment (n = 30, age 76.7yrs ± SD12.1, p = 0.84) met daily requirements for energy (70.7% ± SD16.8 vs. 70.7% ± SD17.3, p = 0.94) or protein intake (73.2% ± SD18.6 vs. 69.8% ± SD17.3, p = 0.70). Mean body weight dropped: standard care 0.92 kg ± SD2.47 vs. enriched 0.64 kg ± SD3.12 (p = 0.53) and malnutrition increased: standard care 3.3%-26.6% vs. enriched 6.6%-13.3% (p = 0.07). Predictors of malnutrition on discharge in logistic regression models were: length of stay (p < 0.01) and protein (p < 0.01) or energy intake (p = 0.02).

CONCLUSIONS

Acute stroke patients were not meeting nutritional requirements and losing body weight. The enriched environment showed no effect on nutritional intake. Malnutrition was associated with lower energy and protein intakes and increased length of stay.

A New Model for the Oxyhaemoglobin Dissociation Curve

This paper describes a new model for the oxygen-haemoglobin dissociation curve in humans.

The model is based on the known structural alterations that occur in the quaternary haemoglobin molecule during oxygenation and deoxygenation. The two alternative structures, tense and relaxed, are described using hyperbolic tangent curves and linked with a probability function to obtain the completed mathematical description of the oxygen-haemoglobin dissociation curve. Model accuracy is assessed by a bias/precision analysis of calculated logit (S) and P50 against gold standard data. A mechanism for the transition between the two structures involving the chloride ion as a major allosteric effector is proposed.

Results were analysed against the Siggaard-Andersen model for bias, precision and calculated P50 in four saturation ranges—0.00<SO 2< 1.00, 0.20<SO 2< 0.80, 0.90<SO 2< 1.00 and 0.97<SO 2< 1.00. In each range except for 0.20<SO 2 <0.80, bias, precision and calculated P50 for the new model are significantly better (P<0.05). Analysis of calculated P50 across the entire saturation range revealed significant drift out of the acceptable range in the Siggaard-Andersen model for SO 2 >0.92. The new model remained within tolerance across the saturation range 0.00<SO 2 <1.00.

The new model is significantly more accurate than the popular Siggaard-Andersen model, particularly in the range SO 2> 0.90.

Near-Hanging as Presenting to Hospitals in Queensland: Recommendations for Practice

Near-hanging is an increasing presentation to hospitals in Australasia. We reviewed the clinical management and outcome of these patients as they presented to public hospitals in Queensland. A retrospective clinical record audit was made at five public hospitals between 1991 and 2000. Of 161 patients enrolled, 82% were male, 8% were indigenous and 10% had made a previous hanging attempt. Chronic medical illnesses were documented in 11% and previous psychiatric disorders in 42%. Of the 38 patients with a Glasgow Coma Scale score (GCS) of 3 on arrival at hospital, 32% returned to independent living and 63% died. Fifty-two patients received CPR, of whom 46% had an independent functional outcome. Independent predictors of mortality were a GCS on hospital arrival of 3 (AOR 150, CI 95% 12.4–1818, P<0.001), taking plain X-rays of the cervical spine (AOR 0.06, CI 95% 0.004–0.97, P=0.047) and contact with the ground (AOR 0.03, CI 95% 0.002–0.62, P=0.02). Only 66% had imaging of the cervical spine performed with other imaging performed infrequently. There were three laryngeal, two hyoid bone and three cervical spine injuries and one carotid dissection. The number of cervical spine X-rays required to find a significant cervical spine fracture was 54. Near-hanging presenting to hospital with a poor conscious state or even cardiac arrest can have a favourable clinical outcome. Radiological investigations are infrequently performed despite a low GCS precluding early accurate assessment. Given the general favourable outcome, an aggressive approach to searching for correctable injuries is recommended.

Allostasis and sedation practices in intensive care evaluation: an observational pilot study

Background

A dysregulated stress response has been implicated in the pathogenesis of critical illness. Sedative agents utilised in the critically unwell patient may impact upon the stress response with a downstream negative effect on multiple organ systems. This study was designed to assess the feasibility of investigating components of the stress response as a sub-study of the current SPICE-III study (NCT01728558).

Methods

This pilot observational cohort study was conducted in a single intensive care unit in Queensland, Australia. Enrolled patients were over 18 years who had been commenced on mechanical ventilation requiring sedation for less than 12 h but expected to remain ventilated for > 24 h. Blood samples were taken at 12 h intervals over a 5-day period commencing at the time of enrolment, and subsequently tested for various markers of key efferent limbs of the stress axis.

Results

The 12 patients recruited closely mirrored the population within the pilot study used to design SPICE-III. Eighty-nine percent (107/120) of all planned blood samples were obtained and drawn within 0 h (0–0.3) of the planned sampling time point. Time from eligibility to enrolment was a median (IQR) 1.4 h (0.36–9.19), and time from eligibility to the first blood sample was 4.79 h (2.0–10.61). Physiological, hormonal, metabolic and cardiac biomarkers were consistent with an elevated stress response at baseline which mostly normalised over the 5-day study period. Plasma noradrenaline levels correlated with the dose of norepinephrine used.

Conclusions

A larger sub-study of the SPICE-III study is feasible. The study has demonstrated a predictable trend of variation of the components of the blood panel during the evolution of critical illness and supports multiple sampling time points for the follow-up study.

Trial registration

ANZCTR.org.au, ACTRN12616001200471, Registered on 22 January 2016.

An assessment of the tolerability of the Cook staged extubation wire in patients with known or suspected difficult airways extubated in intensive care

The Cook staged extubation set (Cook Medical) has been developed to facilitate management of the difficult airway. A guidewire inserted before tracheal extubation provides access to the subglottic airway should re-intubation be required. This prospective cohort study examines patients' tolerance of the guidewire and its impact on clinical status around tracheal extubation in the intensive care unit. Vital signs, incidence of symptoms and patient tolerance of the wire were recorded. Twenty-three patients were enrolled and 17 (73%) tolerated the wire for 4 h. Nasendoscopy was performed in 11 of these patients and revealed one wire was in the oesophagus. The most common symptom was a mild intermittent cough in 13 patients. There was no impact of the guidewire on nursing care in 16 patients, tolerable impact in five and severe impact necessitating removal of the wire in one patient.

Patients with Bacteraemia Discharged from the Department of Emergency Medicine: Distribution of Organisms and Associated Characteristics

Introduction

Although blood cultures are commonly used to investigate febrile patients presenting to an emergency department, treatment decisions usually have to be made before the results are available.

Methods

We performed a retrospective analysis of consecutive patients presenting with community-acquired bacteraemia at the emergency department of Nambour Hospital, Queensland, Australia between 2000 and 2008. We determined their clinical characteristics, the distribution of organisms and also assessed patient characteristics associated with discharge from the emergency department.

Results

A total of 885 patients with 915 presentations of community-acquired bacteraemia were included. While having bacteraemia, 33 patients (3.6%) were discharged from the emergency department. Age, mode of presentation, altered mental state, presence of immunocompromise, presence of respiratory distress, C reactive protein, Charlson score, age score and estimated 10 years survival were significant factors discriminating the admitted from discharged patients. The most commonly found organism in blood cultures of discharged patients was Staphylococcus aureus (27.3%), whereas in admitted patients it was E. coli (27.7%). Methicillin-resistant Staphylococcus aureus accounted for 1.7% of cases of community-acquired bacteraemia.

Conclusions

Emergency physicians only rarely discharge patients with community-acquired bacteraemia using current assessment tools and decision-making rules. However, they tend to discharge younger self-presenting patients with good baseline function.

Intraoperative Cerebral Perfusion Disturbances During Transcatheter Aortic Valve Replacement

BACKGROUND

Transcatheter aortic valve replacement entails profound and unavoidable hemodynamic perturbations that may contribute to the neurological injury associated with the procedure.

METHODS

Thirty-one patients were monitored with cerebral oximetry as a surrogate marker of perfusion while undergoing transcatheter aortic valve replacement via a transfemoral approach under general anesthesia to detect intraoperative hypoperfusion insult. Serial neurologic, cognitive, and cerebral magnetic resonance imaging assessments were administered to objectively quantify perioperative neurologic injury and ascertain any association with significant cerebral oximetry disturbances.

RESULTS

Cerebral oximetry reacted promptly to rapid ventricular pacing with significant cerebral desaturation, relative to baseline, of greater than 12% and greater than 20% in 12 of 31 (68%) and 9 of 31 (29%) patients, respectively; or to an absolute measurement of less than 50% in 10 of 31 (33%) patients. Hyperemia occurred immediately following relief of aortic stenosis exceeding baseline by greater than 10% and greater than 20% in 14 of 31 (45%) and 5 of 31 (16%) patients. Postoperative cognitive dysfunction was evident in 3 of 31 (10%) patients and new magnetic resonance imaging-defined ischemic lesions were seen in 17 of 28 (61%) patients. No patient experienced clinically apparent stroke.

CONCLUSIONS

Cerebral oximetry reacted promptly to rapid ventricular pacing with significant desaturation and hyperemia a common occurrence. However, no association between this intraoperative insult and objective neurologic injury was detected.

Reliability of thermodilution derived cardiac output with different operator characteristics

Cardiac output (CO) is commonly measured using the thermodilution technique at the time of right heart catheterisation (RHC). However inter-operator variability, and the operator characteristics which may influence that, has not been quantified. Therefore, this study aimed to assess inter-operator variability with the thermodilution technique using a mock circulation loop (MCL) with calibrated flow sensors. Participants were blinded and asked to determine 4 levels of CO using the thermodilution technique, which was compared with the MCL calibrated flow sensors. The MCL was used to randomly generate CO between 3.0 and 7.0 L/min through changes in heart rate, contractility and vascular resistance with a RHC inserted through the MCL pulmonary artery. Participant characteristics including gender, specialty, age, height, weight, body-mass index, grip strength and RHC experience were recorded and compared to determine their relationship with CO measurement accuracy. In total, there were 15 participants, made up of consultant cardiologists (6), advanced trainees in cardiology (5) and intensive care consultants (4). The majority (9) had performed 26-100 previous RHCs, while 4 had performed more than 100 RHCs. Compared to the MCL-measured CO, participants overestimated CO using the thermodilution technique with a mean difference of +0.75 ± 0.71 L/min. The overall r² value for actual vs measured CO was 0.85. The difference between MCL and thermodilution derived CO declined significantly with increasing RHC experience (P < 0.001), increasing body mass index (P < 0.001) and decreasing grip strength (P = 0.033). This study demonstrated that the thermodilution technique is a reasonable method to determine CO, and that operator experience was the only participant characteristic related to CO measurement accuracy. Our results suggest that adequate exposure to, and training in, the thermodilution technique is required for clinicians who perform RHC.

A Comparison between Two Dilute Citrate Solutions (15 vs. 18 mmol/l) in Continuous Renal Replacement Therapy: The Base Excess and Renal Substitution Solution Study

Background/Aims: The study aimed to compare the changes in biochemistry occurring in patients undergoing continuous renal replacement therapy (CRRT) using 2 trisodium citrate solutions, Baxter hemofiltration fluid containing 18 mmol/l (C18) and Baxter NamSol, a custom manufactured solution containing 15 mmol/l (C15), both delivered as regional citrate anticoagulation (RCA) predilution fluids for hemofiltration. Methods: This is a prospective randomized control trial conducted in a major regional adult intensive care unit. Patients were randomized to 1 of 2 RCA fluids. Progress was monitored using a standard daily panel of acid-base and biochemical tests. Results: Forty-eight patients, 23 C18 and 25 C15, were recruited. In both groups, acidosis resolved within 36 h of institution of CRRT. By day 3, there were significant differences in serum [Na+], standard base excess and serum bicarbonate concentration, all being higher in the C18 group (p < 0.01). By day 5, the PaCO2 had also risen in the C18 group (p = 0.03). Conclusions: The C15 solution provided equivalent filter life to the C18 solution but without significant hypernatremia and metabolic alkalosis.

Transition From Heparin to Citrate Anticoagulation for Continuous Renal Replacement Therapy: Safety, Efficiency, and Cost

Regional citrate anticoagulation (RCA) for continuous renal replacement therapy (CRRT) has recently been recommended as first-line over heparin. Evidence suggests that RCA prolongs filter life and may reduce bleeding risk, but there is little research on the benefits to dialysis dose delivery or cost, or the effectiveness of transitioning to RCA first-line. The aim of the present study was to assess the effect on dialysis delivery, cost and safety when transitioning from systemic heparin to RCA for first-line anticoagulation for CRRT. A single-center, retrospective observational study was conducted from 2006 to 2012, during which a transition from heparin to a simplified RCA protocol occurred. Demographic and dialysis data, pathology results and costs were obtained. Data were analyzed for both heparin and RCA, and for before and after the transition. 166 patients had 992 dialysis days (heparin 334 vs. RCA 658); demographics were well matched; RCA used less filters per day (P = 0.03), had more days when prescribed dialysis was achieved (85% vs. 60%, P < 0.001), and less filter "down-time" per day (2.4 vs. 6.1 h, P = 0.02). RCA was estimated to cost AU$487 per day, compared to heparin at $479 per day. When the data were analyzed, comparing before and after the transition, these results remained statistically significant. There was no statistical difference in clinical safety events. Transition to first-line RCA was safe, provided more time on filter and consumed less filter circuits using a simple and user friendly protocol. The adjusted cost difference appears negligible.

Protein-bound drugs are prone to sequestration in the extracorporeal membrane oxygenation circuit: results from an ex vivo study

Introduction

Vital drugs may be degraded or sequestered in extracorporeal membrane oxygenation (ECMO) circuits, with lipophilic drugs considered to be particularly vulnerable. However, the circuit effects on protein-bound drugs have not been fully elucidated. The aim of this experimental study was to investigate the influence of plasma protein binding on drug disposition in ex vivo ECMO circuits.

Methods

Four identical ECMO circuits comprising centrifugal pumps and polymethylpentene oxygenators and were used. The circuits were primed with crystalloid, albumin and fresh human whole blood and maintained at a physiological pH and temperature for 24 hours. After baseline sampling, known quantities of study drugs (ceftriaxone, ciprofloxacin, linezolid, fluconazole, caspofungin and thiopentone) were injected into the circuit to achieve therapeutic concentrations. Equivalent doses of these drugs were also injected into four polypropylene jars containing fresh human whole blood for drug stability testing. Serial blood samples were collected from the controls and the ECMO circuits over 24 hours, and the concentrations of the study drugs were quantified using validated chromatographic assays. A regression model was constructed to examine the relationship between circuit drug recovery as the dependent variable and protein binding and partition coefficient (a measure of lipophilicity) as explanatory variables.

Results

Four hundred eighty samples were analysed. There was no significant loss of any study drugs in the controls over 24 hours. The average drug recoveries from the ECMO circuits at 24 hours were as follows: ciprofloxacin 96%, linezolid 91%, fluconazole 91%, ceftriaxone 80%, caspofungin 56% and thiopentone 12%. There was a significant reduction of ceftriaxone (P = 0.01), caspofungin (P = 0.01) and thiopentone (P = 0.008) concentrations in the ECMO circuit at 24 hours. Both protein binding and partition coefficient were highly significant, with the model possessing a high coefficient of determination (R² = 0.88, P <0.001).

Conclusions

Recovery of the highly protein-bound drugs ceftriaxone, caspofungin and thiopentone was significantly lower in the ECMO circuits at 24 hours. For drugs with similar lipophilicity, the extent of protein binding may determine circuit drug loss. Future clinical population pharmacokinetic studies should initially be focused on drugs with greater lipophilicity and protein binding, and therapeutic drug monitoring should be strongly considered with the use of such drugs.

Has the incidence of hypoxic ischaemic encephalopathy in Queensland been reduced with improved education in fetal surveillance monitoring?

BACKGROUND

Hypoxic ischaemic encephalopathy (HIE) is secondary to intrapartum asphyxia and the fifth largest cause of death of children under five. Incorrect use and interpretation of intrapartum cardiotocographs has been identified as a contributing factor to the development of HIE. Therefore, RANZCOG introduced the Fetal Surveillance Education Program (FSEP) to improve education and practice of intrapartum care.

AIM

To investigate the incidence of HIE throughout Queensland between 2003 and 2011 during the introduction and implementation of RANZCOG FSEP.

METHODS

The incidence of HIE admissions at each hospital in Queensland (2003-2011) was collated from Queensland Health Statistics Centre. RANZCOG FSEP provided data regarding course attendees throughout Queensland (2006-2011). Hospitals were grouped into four regions. Statistical analysis was conducted using Stata(TM) (version 12.0) - data appeared to follow a damped harmonic model.

RESULTS

The posteducation (2006-2011) HIE rate was significantly lower (P = 0.02) than the pre-education (2003-2005) rate. The final model predicted a stabilisation of HIE occurrence rate at approximately 160 events/100,000 live births by 2012. This rate was stable if the level of education was maintained but rose back to the initial rate of 250 events/100,000 live births if the education participation was discontinued.

CONCLUSIONS

This study identified a significant reduction in the incidence of HIE--a potentially life-threatening newborn condition--between 2003 and 2011, during and following FSEP implementation. Notwithstanding the inevitable limitations of state-based data collection, these results are encouraging. For such improvements to be sustained, education must reach all staff engaged in intrapartum care and be regularly repeated.

Managing cardiovascular collapse in severe flecainide overdose without recourse to extracorporeal therapy

Flecainide overdose can rapidly result in profound cardiovascular collapse, and is associated with a relatively high mortality. A case is described where a woman with major toxicity and high serum levels was managed without recourse to invasive modalities such as cardiopulmonary bypass or extracorporeal therapies. Hypertonic sodium bicarbonate is recognized as effective therapy for hypotension and arrhythmias. More recent case reports have concentrated on the use of cardiopulmonary bypass. In this report and other reports describing successful resuscitation, the total dose of sodium bicarbonate is conspicuously higher than in reports describing extracorporeal interventions. Sodium bicarbonate should be given early in the resuscitation, and re-administered as frequently as required, targeting an alkaline pH and improved cardiac output, while accepting hypernatraemia. This case demonstrates the maxim that the correct dose of hypertonic sodium bicarbonate is 'enough'. Cardiopulmonary bypass support can be considered as a salvage therapy.

A new model for the oxyhaemoglobin dissociation curve

This paper describes a new model for the oxygen-haemoglobin dissociation curve in humans. The model is based on the known structural alterations that occur in the quaternary haemoglobin molecule during oxygenation and deoxygenation. The two alternative structures, tense and relaxed, are described using hyperbolic tangent curves and linked with a probability function to obtain the completed mathematical description of the oxygen-haemoglobin dissociation curve. Model accuracy is assessed by a bias/precision analysis of calculated logit (S) and P50 against gold standard data. A mechanism for the transition between the two structures involving the chloride ion as a major allosteric effector is proposed. Results were analysed against the Siggaard-Andersen model for bias, precision and calculated P50 in four saturation ranges--0.00 < SO2 < 1.00, 0.20 < SO2 < 0.80, 0.90 < SO2 < 1.00 and 0.97 < SO2 < 1.00. In each range except for 0.20 < SO2 < 0.80, bias, precision and calculated P50 for the new model are significantly better (P < 0.05). Analysis of calculated P50 across the entire saturation range revealed significant drift out of the acceptable range in the Siggaard-Andersen model for SO2 > 0.92. The new model remained within tolerance across the saturation range 0.00 < SO2 < 1.00. The new model is significantly more accurate than the popular Siggaard-Andersen model, particularly in the range SO2 > 0.90.

Dietary exposure of finfish to aromatic contaminants and tissue distribution

Large rainbow trout (400 g) were exposed to food pellets spiked with four polycyclic aromatic compounds (PACs). Muscle, liver, internal organs, fatty tissue, and blood were analyzed after 5, 10, 15, and 19 weeks for PAC, lipid, and moisture content. At all collection times, concentrations expressed on a per gram basis were higher in fatty tissue and internal organs, followed by liver and muscle, and lowest levels were observed in blood. When examining the tissue burden, the highest bioaccumulations of carbazole, dibenzofuran, dibenzothiophene, and fluorene were in muscle and internal organs, intermediate in fatty tissue, and lowest in blood and liver. Carbazole with the lowest log K(OW) showed the lowest concentration within any tissue. Levels in tissues were significantly correlated to log K(OW) (> 5% level of significance), especially with longer exposure, and were more highly correlated when examining muscle, fatty tissue, and internal organs (> 0.05%). Different tissues displayed different time trends, and ratios between organs help determine the length of exposure. The most striking change in levels observed with time was in internal organs relative to other tissues, particularly when compared to daily exposure. The elimination of contaminants in feces and gallbladder bile was also compared, because they represent additional tools to assess recent exposure.

The accuracy of in vivo P50 at high haemoglobin saturation

The in vivo P50 (P50iv) provides a useful index of haemoglobin-oxygen affinity and is calculated according to software algorithms incorporated into commercial blood gas analysers. These algorithms are known to be inaccurate at high haemoglobin saturation (SpO2 > 97%) although just how inaccurate has not been documented. This study examines the arterial blood gas profiles of patients admitted to a busy secondary referral Intensive Care Unit and stratifies them according to haemoglobin saturation in order to quantify the accuracy and potential clinical utility of the Siggaard-Andersen algorithm (SAA) for assessing P50iv in blood with SpO2 > 90%. Sicker patients, as identified by plasma pH < 7.35 or [lactate] > 2.0 mmol/l, were substratified and the SAA assessed as before. In both groups, the results show not only that the SAA is completely unreliable above 97% saturation, a fact acknowledged by Siggaard-Andersen in 1984, but it is also inaccurate in the range 92% < or = SpO2 < or = 97%, thus rendering P50iv calculations suspect in 90% of the patients in each of the study groups.