The impact of obesity on body surface area adjusted estimated glomerular filtration rate in patients with chronic kidney disease.

BACKGROUND: Assessment of kidney function is necessary for prescribing renally excreted drugs. The estimated glomerular filtration rate (eGFR) routinely reported by laboratories is indexed to a body surface area (BSA) of 1.73 m2. In obese patients, the indexed eGFR may underestimate directly measured GFR. AIMS: To determine the prevalence of obesity in patients with chronic kidney disease (CKD) and examine the effect of adjusting the indexed eGFR for patient BSA (deindexing) across CKD Stages 2-5. METHODS: We conducted a cross-sectional study of 575 adults with stable CKD from two general nephrology clinics over 6 months. Dialysis and kidney transplant patients were excluded. We used four equations (Mosteller, Dubois, Haycock and Schlich) to determine BSA based on actual body weight and applied Bland-Altman plots and piecewise linear regression to examine the relationship between deindexed and indexed eGFR. RESULTS: The median age was 68 years (58% male). The prevalence of overweight and obesity was 31% and 47% respectively. Mean body mass index was 29.7 kg/m2. The Schlich equation for BSA produced the smallest adjustment in eGFR, while the Haycock equation produced the largest adjustment. Males experienced the largest change in eGFR from deindexing because of larger BSAs. Although bias became increasingly positive with higher eGFR, the linear regression stratified by CKD stage indicated that deindexing had little impact with eGFR <45 mL/min/1.73 m2. CONCLUSIONS: In CKD, deindexing the Chronic Kidney Disease Epidemiology Collaboration eGFR may not be necessary when the eGFR is <45 mL/min/1.73 m2, particularly if the patient is female.

Impact of electronic medical records and COVID-19 on adult Goals-of-Care document completion and revision in hospitalised general medicine patients.

BACKGROUND: Conversion from paper-based to electronic medical records (EMR) may affect the quality and timeliness of the completion of Goals-of-Care (GOC) documents during hospital admissions and this may have been further impacted by the COVID-19 pandemic. AIMS: To determine the impact of EMR and COVID-19 on the proper completion of GOC forms and the factors associated with inpatient changes in GOC. METHODS: We conducted a cross-sectional study of adult general medicine admissions (August 2018-September 2020) at Dandenong Hospital (Victoria, Australia). We used interrupted time series to model the changes in the rates of proper GOC completion (adequate documented discussion, completed ≤2 days) after the introduction of EMR and the arrival of COVID-19. RESULTS: We included a total of 5147 patients. The pre-EMR GOC proper completion rate was 27.7% (overall completion, 86.5%). There was a decrease in the proper completion rate by 2.21% per month (95% confidence interval (CI): -2.83 to -1.58) after EMR implementation despite an increase in overall completion rates (91.2%). The main reason for the negative trend was a decline in adequate documentation despite improvements in timeliness. COVID-19 arrival saw a reversal of this negative trend, with proper completion rates increasing by 2.25% per month (95% CI: 1.35 to 3.15) compared with the EMR period, but also resulted in a higher proportion of GOC changes within 2 days of admission. CONCLUSIONS: EMR improved the timeliness and overall completion rates of GOC at the cost of a lower quality of documented discussion. COVID-19 reversed the negative trend in proper GOC completion but increased the number of early revisions.

Intraoperative vasopressor use and early postoperative acute kidney injury in elderly patients undergoing elective noncardiac surgery.

BACKGROUND: Intraoperative hypotension is a risk factor for postoperative acute kidney injury (AKI). Elderly patients are susceptible due to reduced responses to acute hemodynamic changes. AIMS: Determine the association between hypotension identified from anesthetic charts and postoperative AKI in elderly patients. METHODS: Retrospective cohort study of elective noncardiac surgery patients ≥65 years, at an Australian tertiary hospital (December 2019-March 2021), with the primary outcome of AKI ≤48 h of surgery. Factors of interest were intraoperative hypotension determined from anesthetic charts (mean arterial pressure <60 mmHg, systolic blood pressure <90 mmHg, recorded 5-min) and intraoperative vasopressor use. RESULTS: In 830 patients (mean age 75 years), systolic hypotension was more frequent than mean arterial hypotension (25.7% vs. 11.9%). Most hypotensive episodes were brief (7.2% of systolic and 4.2% of mean arterial hypotension lasted >10 min) but vasopressors were used in 84.7% of cases. The incidence of postoperative AKI was 13.9%. Systolic hypotension >20 min was associated with AKI (OR, 3.88; 95% CI: 1.38-10.9), which was not significant after adjusting for vasopressors, creatinine, American Society of Anesthesiologists class, and hemoglobin drop. The cumulative dose of any specific vasopressor >20 mg (or >10 mg epinephrine) was independently associated with AKI (adjusted OR, 2.47; 95% CI: 1.34-4.58). Every 5 mg increase in the total dose of all intraoperative vasopressors used during surgery was associated with 11% increased odds of AKI (95% CI: 3-19%). CONCLUSIONS: High vasopressor use was associated with postoperative AKI in elderly patients undergoing noncardiac surgery, independent of hypotension identified from anesthetic charts.

Observational study of the incidence and factors associated with patient readmission from home-based care under the Hospital in the Home programme.

BACKGROUND: Hospital in the Home (HITH) provides home-based care by hospital staff, which reduces inpatient length of stay and promotes a better quality of life. The frequency and precipitants for readmission from HITH back to the acute inpatient service are currently poorly defined. AIMS: To determine the incidence of hospital readmissions and risk factors for readmissions in a HITH programme of a large hospital network. METHODS: We conducted a retrospective cohort study of adult patients admitted to a large HITH service within a hospital network in Victoria, Australia, from 1 July to 30 September 2017. We used logistic regression to determine if patient characteristics or specific clinical factors were associated with hospital readmission. RESULTS: In a cohort of 605 patients under HITH, 72 were readmitted (incidence 11.9%). The median duration under HITH prior to readmission was 7 days (interquartile range, 3-23 days). Most readmissions were due to treatment failure, an associated complication or new clinical problem. In the univariable analysis, older age, direct admission from the emergency department (ED), recent intensive care admission, high Charlson comorbidity index, advanced chronic kidney disease, negative pressure wound therapy and use of antihypertensives were factors associated with readmission. In the multivariable analysis, the variables independently associated with readmissions were the Charlson comorbidity index (odds ratio, OR 1.17, 95% CI: 1.08-1.25) and referrals from the ED (OR 0.18, 95% CI: 0.06-0.58). CONCLUSIONS: Older age and greater comorbidity increased the odds of readmission, but patients from the ED were low risk compared to inpatient referrals.

Patient factors affecting the proper completion of a goals-of-care form in a general medicine hospital admission.

BACKGROUND: The goals-of-care (GOC) form is a resuscitation planning tool used to document informed decisions tailored for individual patients admitted to hospital. Proper and timely completion of the GOC form is essential for its effective utility. AIMS: To identify patient factors which may affect the timely discussion and documentation of GOC forms in patients admitted under a general medicine unit. METHODS: We performed a cross-sectional study of 2589 patients during 3093 admissions under the general medicine unit from January 2017 to July 2017 at Dandenong Hospital in Melbourne, Australia. The main outcome was the proper completion of GOC forms, defined as GOC completion within 48 h of admission and adequate discussion with the patient or substitute decision maker. We used logistic regression to determine the association between the main outcome and several patient-related independent variables. RESULTS: A GOC form was completed in 66% of all admissions but only 35% were considered properly completed (timely and adequately discussed). In the general multivariable logistic regression model, the variables associated with proper completion of GOC forms were age (OR = 1.58), English as the main spoken language (OR = 1.43) and readmissions (OR = 1.27). In patients 75 years and older, additional factors associated with proper GOC completion were confusion on admission (OR = 1.31) and number of comorbidities (OR = 1.27). CONCLUSIONS: The proper GOC form completion rates were suboptimal in general medicine admissions, particularly in younger patients with fewer comorbidities. Additional effort is needed to improve GOC completion in these patients and those whose primary spoken language is not English.

An International Report on the Adaptations of Rapid Transient Ischaemic Attack Pathways During the COVID-19 Pandemic.

BACKGROUND: This report aims to describe changes that centres providing transient ischaemic attack (TIA) pathway services have made to stay operational in response to the SARS-CoV-2 pandemic. METHODS: An international cross-sectional description of the adaptions of TIA pathways between 30th March and 6th May 2020. Experience was reported from 18 centres with rapid TIA pathways in seven countries (Australia, France, UK, Canada, USA, New Zealand, Italy, Canada) from three continents. RESULTS: All pathways remained active (n = 18). Sixteen (89%) had TIA clinics. Six of these clinics (38%) continued to provide in-person assessment while the majority (63%) used telehealth exclusively. Of these, three reported PPE use and three did not. Five centres with clinics (31%) had adopted a different vascular imaging strategy. CONCLUSION: The COVID pandemic has led TIA clinics around the world to adapt and move to the use of telemedicine for outpatient clinic review and modified investigation pathways. Despite the pandemic, all have remained operational.

Progression to Severe Hypernatremia in Hospitalized General Medicine Inpatients: An Observational Study of Hospital-Acquired Hypernatremia.

Background and objectives: Hypernatremia can be community or hospital-acquired, and there may be specific factors unique to the hospital environment, such as intravenous fluid treatment, which contribute to hypernatremia. The aim of this study was to determine the factors associated with the progression from moderate to severe hospital-acquired hypernatremia among patients admitted under general medicine. Materials and Methods: In this retrospective, single-center cohort study (2012 to 2017), we used ICD-10 coding and medical records to identify adult patients who developed moderate hypernatremia and followed them for progression to severe hypernatremia. We profiled the serum biochemistry and the volume and composition of prescribed intravenous fluids. We applied logistic regression to determine the factors associated with the progression to severe hypernatremia, using the patients with moderate hypernatremia as reference. Results: Of the 180 medical inpatients (median age of 81 years) with moderate hospital-acquired hypernatremia, 9.4% progressed to severe hypernatremia. Normal saline comprised 76% of intravenous fluid volume administered prior to onset of moderate hypernatremia. After the onset, 38% of fluid volume prescribed remained normal saline. The factors independently associated with progression to severe hypernatremia included chronic kidney disease stage (odds ratio 2.38, 95% CI: 1.26-4.50, P = 0.008) and serum creatinine increase (per 10 µmol/L, OR 1.29, 95% CI: 1.07-1.57, P = 0.009). Conclusions: Patients with chronic kidney disease and acute kidney injury may have an increased risk of severe hospital-acquired hypernatremia.

Illicit drug use and acute kidney injury in patients admitted to hospital with rhabdomyolysis.

BACKGROUND: Severe rhabdomyolysis is associated with acute kidney injury, but it is unclear if patients developing rhabdomyolysis after illicit drug use have a higher risk of acute kidney injury compared to other causes. AIMS: To provide a descriptive analysis of patients admitted with rhabdomyolysis, with a focus on illicit drug use, and to determine if illicit drug use was an independent predictor for acute kidney injury or renal replacement therapy. METHODS: We conducted a 5-year cohort study of patients admitted to Monash Health, a tertiary referral hospital network. We identified adult patients with muscle injury from ICD-10 AM codes, serum creatine kinase level greater than 1000 U/mL, and a clinical history consistent with rhabdomyolysis. We determined the prevalence and type of illicit drug involved and determined the association between illicit drug use and renal outcomes by logistic regression. RESULTS: Of 643 patients, illicit drug use was identified in 12%. Acute kidney injury developed in 51%, and 5% required renal replacement therapy. Compared to the rest of the cohort, patients who used illicit drugs were younger and had higher peak serum creatine kinase, and developed a higher severity of acute kidney injury. In multivariable analysis, the factors associated with acute kidney injury were illicit drug use, peak creatine kinase, cardiovascular disease, concurrent sepsis and a clinically-evident pressure injury. Chronic kidney disease and need for fasciotomy were additional risk factors for renal replacement therapy. CONCLUSIONS: Illicit drug use was associated with acute kidney injury and renal replacement therapy independent of creatine kinase levels.

Intracranial haemorrhage detected by cerebral computed tomography after falls in hospital acute medical wards.

BACKGROUND: There is little published data on brain imaging and intracranial haemorrhage after hospital inpatient falls. Imaging protocols for inpatient falls have been adopted from head injury guidelines developed from data in patients presenting to the Emergency Department. We sought to describe the use of brain computed tomography (CT) following inpatient falls, and determine the incidence and potential risk factors for intracranial haemorrhage. METHODS: We identified inpatient falls in acute medical wards at Monash Health, a large hospital network in the southeast region of Melbourne in Australia, from the incident reporting system during a 32 month period. We examined the post-fall medical assessment form, neurological observation chart and the diagnostic imaging system for details of the fall and brain CT findings. We used survival analysis to evaluate the timeliness of brain imaging and determined potential risk factors for intracranial haemorrhage by logistic regression. RESULTS: From 934 falls in 789 medical inpatients, 191 brain CT scans were performed. The median age of patients was 77 years. Only 55% of falls were from standing height and 24% experienced a head strike. Less than 10% of patients received an urgent scan within one hour, and timeliness of imaging was influenced by anticoagulation status rather than guideline determination of urgency. The overall incidence of intracranial haemorrhage was 0.9%. The factors associated with intracranial haemorrhage were head strike, anticoagulation, loss of consciousness or amnesia, drop in Glasgow Coma Scale and advanced chronic kidney disease. CONCLUSIONS: The incidence of intracranial haemorrhage was low as most inpatient falls were at low risk for head injury. Research is needed to determine if guidelines specific for hospital inpatients may reduce unnecessary scans without compromising case detection, and improve timeliness of urgent scans.

Factors associated with anaemia in kidney transplant recipients in the first year after transplantation: a cross-sectional study.

BACKGROUND: Anaemia after kidney transplantation may reduce quality of life, graft or patient survival. We aimed to determine the prevalence and risk factors for anaemia in the initial 12 months after transplantation. METHODS: We conducted a cross-sectional study at 6 and 12 months after transplantation. Anaemia was defined by World Health Organization criteria taking into consideration erythropoietin use. Logistic regression was used to determine the association between demographic, clinical and pharmacological risk factors for the main outcome of moderate-severe anaemia. RESULTS: A total of 336 transplant recipients were included and the prevalence of moderate-severe anaemia was 27.4% at 6 months and 15.2% at 12 months. Lower kidney function, female gender, transferrin saturation below 10% and proteinuria were associated with moderate-severe anaemia at both time points. Recent intravenous immunoglobulin treatment was associated with anaemia at 6 months. Recent infection and acute rejection were also associated with anaemia 12 months. Around 20% of patients had at least one blood transfusion but they were uncommon beyond 3 months. CONCLUSIONS: Anaemia remains highly prevalent requiring treatment with erythropoietin and transfusions. Most identifiable risk factors relate to clinical problems rather than pharmacological management, while markers of iron-deficiency remain difficult to interpret in this setting.

Germanium-on-SOI waveguides for mid-infrared wavelengths.

We report on the development of Germanium-on-SOI waveguides for mid-infrared wavelengths. The strip waveguides have been formed in 0.85 and 2 µm thick Ge grown on SOI substrate with 220 nm thick Si overlayer. The propagation loss for various waveguide widths has been measured using the Fabry-Perot method with temperature tuning. The minimum loss of ~8 dB/cm has been achieved for 0.85 µm thick Ge core using 3.682 µm laser excitation. The transparency of these waveguides has been measured up to at least 3.82 µm.

Fish oil for kidney transplant recipients.

BACKGROUND: Calcineurin inhibitors used in kidney transplantation for immunosuppression have adverse effects that may contribute to nephrotoxicity and increased cardiovascular risk profile. Fish oils are rich in very long chain omega-3 fatty acids, which may reduce nephrotoxicity by improving endothelial function and reduce rejection rates through their immuno-modulatory effects. They may also modify the cardiovascular risk profile. Hence, fish oils may potentially prolong graft survival and reduce cardiovascular mortality. OBJECTIVES: This review aimed to look at the benefits and harms of fish oil treatment in ameliorating the kidney and cardiovascular adverse effects of CNI-based immunosuppressive therapy in kidney transplant recipients. SEARCH METHODS: We searched the Cochrane Kidney and Transplant Specialised Register (up to 17 March 2016) through contact with the Information Specialist using search terms relevant to this review. SELECTION CRITERIA: All randomised controlled trials (RCTs) and quasi-RCTs of fish oils in kidney transplant recipients on a calcineurin inhibitor-based immunosuppressive regimen. RCTs of fish oil versus statins were included. DATA COLLECTION AND ANALYSIS: Data was extracted and the quality of studies assessed by two authors, with differences resolved by discussion with a third independent author. Dichotomous outcomes were reported as risk ratio (RR) and continuous outcome measures were reported as the mean difference (MD) with 95% confidence intervals using the random effects model. Heterogeneity was assessed using a Chi(2) test on n-1 degrees of freedom and the I(2) statistic. Data not suitable for pooling were tabulated and described. MAIN RESULTS: Fifteen studies (733 patients) were suitable for analysis. All studies were small and had variable methodology. Fish oil did not significantly affect patient or graft survival, acute rejection rates, or calcineurin inhibitor toxicity when compared to placebo. Overall SCr was significantly lower in the fish oil group compared to placebo (5 studies, 237 participants: MD -30.63 µmol/L, 95% CI -59.74 to -1.53; I(2) = 88%). In the subgroup analysis, this was only significant in the long-course (six months or more) group (4 studies, 157 participants: MD -37.41 µmol/L, 95% CI -69.89 to -4.94; I(2) = 82%). Fish oil treatment was associated with a lower diastolic blood pressure (4 studies, 200 participants: MD -4.53 mm Hg, 95% CI -7.60 to -1.45) compared to placebo. Patients receiving fish oil for more than six months had a modest increase in HDL (5 studies, 178 participants: MD 0.12 mmol/L, 95% CI 0.03 to 0.21; I(2) = 47%) compared to placebo. Fish oil effects on lipids were not significantly different from low-dose statins. There was insufficient data to analyse cardiovascular outcomes. Fishy aftertaste and gastrointestinal upset were common but did not result in significant patient drop-out. AUTHORS' CONCLUSIONS: There is insufficient evidence from currently available RCTs to recommend fish oil therapy to improve kidney function, rejection rates, patient survival or graft survival. The improvements in HDL cholesterol and diastolic blood pressure were too modest to recommend routine use. To determine a benefit in clinical outcomes, future RCTs will need to be adequately powered with these outcomes in mind.

Acute kidney injury due to glomerular haematuria and obstructive erythrocyte casts associated with thrombocytopaenia and thin basement membrane disease: a case report.

BACKGROUND: Acute kidney injury due to glomerular bleeding has been described with IgA nephropathy and supratherapeutic warfarin anticoagulation. There is usually demonstrable tubular obstruction by erythrocyte casts associated with acute tubular injury. Although severe thrombocytopaenia increases the risk of bleeding, most cases of haematuria have been ascribed to non-glomerular or urological bleeding without a direct link to acute kidney injury. We describe a patient with acute kidney injury due to glomerular bleeding and tubular injury related to severe thrombocytopaenia, who was subsequently found to have thin basement membrane disease. CASE PRESENTATION: A 56 year old man presented with macroscopic haematuria, acute kidney injury and a platelet count of 35 × 10(9)/L, in the absence of anticoagulation. Urinalysis demonstrated an active urinary sediment. His kidney biopsy demonstrated extensive intraluminal erythrocyte casts associated with acute tubular injury, along with haemosiderin deposition suggestive of recurrent glomerular bleeding. There was no histological evidence of glomerular pathology but electron microscopy analysis demonstrated thin basement membrane disease and effacement of podocyte foot processes. During long term follow-up, thrombocytopaenia and intermittent haematuria persisted. At 9 months, the patient progressed to Stage 5 chronic kidney disease with the development of gross renal atrophy. CONCLUSION: Recurrent macroscopic haematuria may be a risk factor for progressive renal injury in patients with thin basement membrane. The mechanism may be due to recurrent acute kidney injury from glomerular bleeding leading to repeated tubular damage. In the absence of anticoagulation, severe thrombocytopaenia may be a risk factor for heavy glomerular bleeding and acute kidney injury in these patients.

CMOS-compatible highly efficient polarization splitter and rotator based on a double-etched directional coupler.

We present a highly efficient polarization splitter and rotator (PSR), fabricated using 248 nm deep ultraviolet lithography on a silicon-on-insulator substrate. The PSR is based on a double-etched directional coupler with a length of 27 µm. The fabricated PSR yields a TM-to-TE conversion loss better than 0.5 dB and TE insertion loss better than 0.3 dB, with an ultra-low crosstalk (-20 dB) in the wavelength regime 1540-1570 nm.

Sagnac loop mirror and micro-ring based laser cavity for silicon-on-insulator.

An integrated laser is a key component in silicon based photonic integrated circuits. Beyond incorporating the gain medium, on-chip cavity design is critical to device performance and yield. Typical recent results involve cavities utilizing distributed Bragg gratings that require ultra-fine feature sizes. We propose to build laser cavity on silicon using a Sagnac loop mirror and a micro-ring wavelength filter for the first time. The Sagnac loop mirror provides broadband reflection, which is simple to fabricate, has an accurately-controlled reflectivity, and negligible excess loss. Single-mode operation is achieved with the intra-cavity micro-ring filter and, using a 248 nm stepper, the laser wavelength can be lithographically controlled within a standard deviation of 3.6 nm. We demonstrate a proof-of-concept device lasing at 1551.7 nm, with 44 dB SMSR, 1.2 MHz linewidth and 4.8 mW on-chip output power.

Silicon microring modulator for 40 Gb/s NRZ-OOK metro networks in O-band.

A microring-based silicon modulator operating at 40 Gb/s near 1310 nm is demonstrated for the first time to our knowledge. NRZ-OOK signals at 40 Gb/s with 6.2 dB extinction ratio are observed by applying a 4.8 Vpp driving voltage and biasing the modulator at 7 dB insertion loss point. The energy efficiency is 115 fJ/bit. The transmission performance of 40 Gb/s NRZ-OOK through 40 km of standard single mode fiber without dispersion compensation is also investigated. We show that the link suffers negligible dispersion penalty. This makes the modulator a potential candidate for metro network applications.

A single adiabatic microring-based laser in 220 nm silicon-on-insulator.

We demonstrate a laser for the silicon photonics platform by hybrid integration with a III/V reflective semiconductor optical amplifier coupled to a 220 nm silicon-on-insulator half-cavity. We utilize a novel ultra-thin silicon edge coupler. A single adiabatic microring based inline reflector is used to select a lasing mode, as compared to the multiple rings and Bragg gratings used in many previous results. Despite the simplified design, the laser was measured to have on-chip 9.8 mW power, less than 220 KHz linewidth, over 45 dB side mode suppression ratio, less than -135 dB/Hz relative intensity noise, and 2.7% wall plug efficiency.

A high-responsivity photodetector absent metal-germanium direct contact.

We report a Ge-on-Si photodetector without doped Ge or Ge-metal contacts. Despite the simplified fabrication process, the device shows a responsivity of 1.14 A/W at -4 V reverse bias and 1.44 A/W at -12V, at 1550 nm wavelength. Dark current is less than 1µA under both bias conditions. We also demonstrate open eye diagrams at 40Gb/s.