Nanoparticle-Based Therapies in Hypertension

Nearly 1.4 billion people worldwide suffer from arterial hypertension, a significant risk factor for cardiovascular disease which is now the leading cause of death. Despite numerous drugs designed to treat hypertension, only ≈14% of hypertensive individuals have their blood pressure under control. A critical factor negatively impacting the efficacy of available treatments is their poor bioavailability. This leads to increased dosing requirements which can result in more side effects, resulting in patient noncompliance. A recent solution to improve dosing and bioavailability issues has been to incorporate drugs into nanoparticle carriers, with over 50 nanodrugs currently on the market across all diseases, and another 51 currently in clinical trials. Given their ability to improve solubility and bioavailability, nanoparticles may offer significant advantages in the formulation of antihypertensives to overcome pharmacokinetic shortcomings. To date, however, no antihypertensive nanoformulations have been clinically approved. This review assesses in vivo study data from preclinical antihypertensive nanoformulation development and testing. Combined, the results of these studies suggest nanoformulation of antihypertensive drugs may be a promising solution to overcome the poor efficacy of currently available antihypertensives, and with further advances has the potential to open paths for new substances that have heretofore been clinically unrealistic due to poor bioavailability.

Dual pH and microbial-sensitive galactosylated polymeric nanocargoes for multi-level targeting to combat ulcerative colitis

Ulcerative colitis (UC) is a type of inflammatory bowel disease characterized by inflammation, ulcers and irritation of the mucosal lining. Oral drug delivery in UC encounters challenges because of multifaceted barriers. Dexamethasone-loaded galactosylated-PLGA/Eudragit S100/pullulan nanocargoes (Dexa-GP/ES/Pu NCs) have been developed with a dual stimuli-sensitive coating responsive to both colonic pH and microbiota, and an underneath galactosylated-PLGA core (GP). The galactose ligand of the GP preferentially binds to the macrophage galactose type-lectin-C (MGL-2) surface receptor. Therefore, both stimuli and ligand-mediated targeting facilitate nanocargoes to deliver Dexa specifically to the colon with enhanced macrophage uptake. Modified emulsion method coupled with a solvent evaporation coating technique was employed to prepare Dexa-GP/ES/Pu NCs. The nanocargoes were tested using in vitro, ex vivo techniques and dextran sodium sulfate (DSS) induced UC model. Prepared nanocargoes had desired physicochemical properties, drug release, cell uptake and cellular viability. Investigations using a DSS-colitis model showed high localization and mitigation of colitis with downregulation of NF-ĸB and COX-2, and restoration of clinical, histopathological, biochemical indices, antioxidant balance, microbial alterations, FTIR spectra, and epithelial junctions' integrity. Thus, Dexa-GP/ES/Pu NCs found to be biocompatible nanocargoes capable of delivering drugs to the inflamed colon with unique targeting properties for prolonged duration.

Effects of preoperative physiotherapy on signs and symptoms of pulmonary collapse and infection after major abdominal surgery: secondary analysis of the LIPPSMAck-POP multicentre randomised controlled trial

Background

Preoperative education and breathing exercise training by a physiotherapist minimises pulmonary complications after abdominal surgery. Effects on specific clinical outcomes such as antibiotic prescriptions, chest imaging, sputum cultures, oxygen requirements, and diagnostic coding are unknown.

Methods

This post hoc analysis of prospectively collected data within a double-blinded, multicentre, randomised controlled trial involving 432 participants having major abdominal surgery explored effects of preoperative education and breathing exercise training with a physiotherapist on postoperative antibiotic prescriptions, hypoxemia, sputum cultures, chest imaging, auscultation, leukocytosis, pyrexia, oxygen therapy, and diagnostic coding, compared to a control group who received a booklet alone. All participants received standardised postoperative early ambulation. Outcomes were assessed daily for 14 postoperative days. Analyses were intention-to-treat using adjusted generalised multivariate linear regression.

Results

Preoperative physiotherapy was associated with fewer antibiotic prescriptions specific for a respiratory infection (RR 0.52; 95% CI 0.31 to 0.85, p = 0.01), less purulent sputum on the third and fourth postoperative days (RR 0.50; 95% CI 0.34 to 0.73, p = 0.01), fewer positive sputum cultures from the third to fifth postoperative day (RR 0.17; 95% CI 0.04 to 0.77, p = 0.01), and less oxygen therapy requirements (RR 0.49; 95% CI 0.31 to 0.78, p = 0.002). Treatment effects were specific to respiratory clinical coding domains.

Conclusions

Preoperative physiotherapy prevents postoperative pulmonary complications and is associated with the minimisation of signs and symptoms of pulmonary collapse/consolidation and airway infection and specifically results in reduced oxygen therapy requirements and antibiotic prescriptions.

Trial registration

ANZCTR 12613000664741; 19/06/2013.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13741-021-00206-3.

Housing R6/2 Mice with Wild-Type Littermates Increases Lifespan

The R6/2 murine model of Huntington's disease (HD) is extensively used in HD research. The current study replicates and extends previous work assessing the impact of housing R6/2 mice with healthy wild-type (WT) littermates on disease progression. The current study extends the previous finding by including male cohorts and the use of a standard diet and water regimen, as opposed to the enhanced diet used in the previous study. This study found that the inclusion of healthy wild-type (WT) littermates, alone, improved survivabilty in R6/2 mice, but did not have a significant impact on weight loss.

Solid Lipid Curcumin Particles Protect Medium Spiny Neuronal Morphology, and Reduce Learning and Memory Deficits in the YAC128 Mouse Model of Huntington's Disease

Huntington's disease (HD) is a genetic neurodegenerative disorder characterized by motor, cognitive, and psychiatric symptoms, accompanied by massive neuronal degeneration in the striatum. In this study, we utilized solid lipid curcumin particles (SLCPs) and solid lipid particles (SLPs) to test their efficacy in reducing deficits in YAC128 HD mice. Eleven-month-old YAC128 male and female mice were treated orally with SLCPs (100 mg/kg) or equivalent volumes of SLPs or vehicle (phosphate-buffered saline) every other day for eight weeks. Learning and memory performance was assessed using an active-avoidance task on week eight. The mice were euthanized, and their brains were processed using Golgi-Cox staining to study the morphology of medium spiny neurons (MSNs) and Western blots to quantify amounts of DARPP-32, brain-derived neurotrophic factor (BDNF), TrkB, synaptophysin, and PSD-95. We found that both SLCPs and SLPs improved learning and memory in HD mice, as measured by the active avoidance task. We also found that SLCP and SLP treatments preserved MSNs arborization and spinal density and modulated synaptic proteins. Our study shows that SLCPs, as well as the lipid particles, can have therapeutic effects in old YAC128 HD mice in terms of recovering from HD brain pathology and cognitive deficits.

The effect of advanced recovery room care on postoperative outcomes in moderate-risk surgical patients: a multicentre feasibility study

Postoperative complications are common and may be under-recognised. It has been suggested that enhanced postoperative care in the recovery room may reduce in-hospital complications in moderate- and high-risk surgical patients. We investigated the feasibility of providing advanced recovery room care for 12-18 h postoperatively in the post-anaesthesia care unit. The primary hypothesis was that a clinical trial of advanced recovery room care was feasible. The secondary hypothesis was that this model may have a sustained impact on postoperative in-hospital and post-discharge events. This was a multicentre, prospective, feasibility before-and-after trial of moderate-risk patients (predicted 30-day mortality of 1-4%) undergoing non-cardiac surgery and who were scheduled for postoperative ward care. Patients were managed using defined assessment checklists and goals of care in an advanced recovery room care setting in the immediate postoperative period. This utilised existing post-anaesthesia care unit infrastructure and staffing, but extended care until the morning of the first postoperative day. The advanced recovery room care trial was deemed feasible, as defined by the recruitment and per protocol management of > 120 patients. However, in a specialised cancer centre, recruitment was slow due to low rates of eligibility according to narrow inclusion criteria. At a rural site, advanced recovery room care could not be commenced due to logistical issues in establishing a new model of care. A definitive randomised controlled trial of advanced recovery room care appears feasible and, based on the indicative data on outcomes, we believe this is warranted.

An Introductory Guide to Survey Research in Anaesthesia

Surveys allow convenient and inexpensive research. Surveys include mail-out questionnaires, email questionnaires, telephone interviews, and personal interviews. Despite a widespread perception that surveys are easy to conduct, good surveys need rigorous design, implementation and analysis. This requires substantial planning, time and effort. The most important step in designing a survey is to clearly define the question (s) the survey aims to answer. The target population, measured variables and types of associations being investigated should be specific and unambiguous. Investigators should concentrate on what they ‘need to know’ rather than what would be ‘nice to know’. During development surveys should be piloted to identify problems. The main goal when implementing a survey is to maximize the response rate to avoid misleading results. Evidence-based strategies, including brief personalized surveys with stamped return envelopes, can be used to maximize the response rate. A poorly conducted survey can lead to misleading or invalid conclusions and may undermine participation in subsequent surveys by the target population.

The Pregnant Trauma Patient

Trauma is the leading non-obstetric cause of maternal death. Optimal management of the pregnant trauma patient requires a multidisciplinary approach. The anaesthetist and critical care physician play a pivotal role in the entire continuum of fetomaternal care, from initial assessment, resuscitation and intraoperative management, to postoperative care that often involves critical care support and patient transfer. Primary goals are aggressive resuscitation of the mother and maintenance of uteroplacental perfusion and fetal oxygenation by the avoidance of hypoxia, hypotension, hypocapnia, acidosis and hypothermia. Recognizing and understanding the mechanisms of injury, the factors that may predict fetal outcome, and the pathophysiological changes that can result from trauma, will allow early identification and treatment of fetomaternal injury. This in turn should improve morbidity and mortality. A framework for the acute care of the pregnant trauma patient is presented.

Perioperative Pulse Contour Cardiac Output Analysis in a Patient with Severe Cardiac Dysfunction

We describe a patient with severe left ventricular dysfunction simultaneously monitored with pulse contour cardiac output (PiCCO) analysis, a continuous cardiac output pulmonary artery catheter (continuous COPAC) and intraoperative transoesophageal echocardiography (TOE).

There was good agreement between cardiac output (CO) measurements obtained by the three techniques prior to cardiopulmonary bypass (CPB). Agreement of CO measurements following CPB was initially poor, but improved following recalibration of PiCCO.

PiCCO-derived global end-diastolic volume index (GEDVI) and cardiac function index (CFI), were assessed as markers of left ventricular preload and myocardial contractility, respectively. GEDVI correlated well with CO in the postoperative period.

CFI increased more than two -fold following coronary revascularization and milrinone administration, and there was also a temporal relationship between the CFI and the dose of milrinone in the first 24 hours of treatment.

Global end-diastolic volume and cardiac function index may be useful additional measures of left ventricular preload and myocardial contractility in patients with severe left ventricular dysfunction.

Transplantation of mesenchymal stem cells genetically engineered to overexpress interleukin-10 promotes alternative inflammatory response in rat model of traumatic brain injury

Background

Traumatic brain injury (TBI) is a major cause for long-term disability, yet the treatments available that improve outcomes after TBI limited. Neuroinflammatory responses are key contributors to determining patient outcomes after TBI. Transplantation of mesenchymal stem cells (MSCs), which release trophic and pro-repair cytokines, represents an effective strategy to reduce inflammation after TBI. One such pro-repair cytokine is interleukin-10 (IL-10), which reduces pro-inflammatory markers and trigger alternative inflammatory markers, such as CD163. In this study, we tested the therapeutic effects of MSCs that were engineered to overexpress IL-10 when transplanted into rats following TBI in the medial frontal cortex.

Methods

Thirty-six hours following TBI, rats were transplanted with MSCs and then assessed for 3 weeks on a battery of behavioral tests that measured motor and cognitive abilities. Histological evaluation was then done to measure the activation of the inflammatory response. Additionally, immunomodulatory effects were evaluated by immunohistochemistry and Western blot analyses.

Results

A significant improvement in fine motor function was observed in rats that received transplants of MSCs engineered to overexpress IL-10 (MSCs + IL-10) or MSCs alone compared to TBI + vehicle-treated rats. Although tissue spared was unchanged, anti-inflammatory effects were revealed by a reduction in the number of glial fibrillary acidic protein cells and CD86 cells in both TBI + MSCs + IL-10 and TBI + MSC groups compared to TBI + vehicle rats. Microglial activation was significantly increased in the TBI + MSC group when compared to the sham + vehicle group. Western blot data suggested a reduction in tumor necrosis factor-alpha in the TBI + MSCs + IL-10 group compared to TBI + MSC group. Immunomodulatory effects were demonstrated by a shift from classical inflammation expression (CD86) to an alternative inflammation state (CD163) in both treatments with MSCs and MSCs + IL-10. Furthermore, co-labeling of both CD86 and CD163 was detected in the same cells, suggesting a temporal change in macrophage expression.

Conclusions

Overall, our findings suggest that transplantation of MSCs that were engineered to overexpress IL-10 can improve functional outcomes by providing a beneficial perilesion environment. This improvement may be explained by the shifting of macrophage expression to a more pro-repair state, thereby providing a possible new therapy for treating TBI.

Diabetes and Associated Cardiovascular Complications in American Indians/Alaskan Natives: A Review of Risks and Prevention Strategies

Diabetes mellitus (DM) is the seventh leading cause of death in the United States and the leading cause of death in the U.S. American Indian/Alaskan Natives (AI/ANs), who comprise only 2% of the total population. The AI/AN population has a high prevalence of DM in adults aged 20 years or older and is developing DM at a younger age than the general U.S.

POPULATION

DM is a major risk factor for cardiovascular disease (CVD), and mortality from CVD is higher in AI/ANs than the general population, as is the prevalence of stroke and 1-year poststroke mortality for both genders when compared to non-Hispanic whites. A genome-wide scan found a number of chromosome linkages in the AI/AN population that suggest that genetic factors may contribute to their high risk of DM and CVD. Importantly, studies also suggest that in addition to race/ethnicity, cultural norms and historic conditions play important roles in the prevalence of DM and CVD in this population. Therefore, multiple factors should be taken into consideration when establishing prevention programs to decrease the prevalence of obesity, diabetes, and CVD incidence among adults and children in the AI/AN population. Prevention programs should focus on behavioral risk factors and lifestyle changes like encouraging smoking cessation, healthy diet, and increased physical activity while taking into consideration cultural, economic, and geographic factors.

Induced Pluripotent Stem Cell-Derived Neural Stem Cell Transplantations Reduced Behavioral Deficits and Ameliorated Neuropathological Changes in YAC128 Mouse Model of Huntington's Disease

Huntington's disease (HD) is a genetic neurodegenerative disorder characterized by neuronal loss and motor dysfunction. Although there is no effective treatment, stem cell transplantation offers a promising therapeutic strategy, but the safety and efficacy of this approach needs to be optimized. The purpose of this study was to test the potential of intra-striatal transplantation of induced pluripotent stem cell-derived neural stem cells (iPS-NSCs) for treating HD. For this purpose, we developed mouse adenovirus-generated iPSCs, differentiated them into neural stem cells in vitro, labeled them with Hoechst, and transplanted them bilaterally into striata of 10-month old wild type (WT) and HD YAC128 mice. We assessed the efficiency of these transplanted iPS-NSCs to reduce motor deficits in YAC128 mice by testing them on an accelerating rotarod task at 1 day prior to transplantation, and then weekly for 10 weeks. Our results showed an amelioration of locomotor deficits in YAC128 mice that received iPS-NSC transplantations. Following testing, the mice were sacrificed, and their brains were analyzed using immunohistochemistry and Western blot (WB). The results from our histological examinations revealed no signs of tumors and evidence that many iPS-NSCs survived and differentiated into region-specific neurons (medium spiny neurons) in both WT and HD mice, as confirmed by co-labeling of Hoechst-labeled transplanted cells with NeuN and DARPP-32. Also, counts of Hoechst-labeled cells revealed that a higher proportion were co-labeled with DARPP-32 and NeuN in HD-, compared to WT- mice, suggesting a dissimilar differentiation pattern in HD mice. Whereas significant decreases were found in counts of NeuN- and DARPP-32-labeled cells, and for neuronal density measures in striata of HD vehicle controls, such decrements were not observed in the iPS-NSCs-transplanted-HD mice. WB analysis showed increase of BDNF and TrkB levels in striata of transplanted HD mice compared to HD vehicle controls. Collectively, our data suggest that iPS-NSCs may provide an effective option for neuronal replacement therapy in HD.

Financial and environmental costs of reusable and single-use anaesthetic equipment

BACKGROUND.

An innovative approach to choosing hospital equipment is to consider the environmental costs in addition to other costs and benefits.

METHODS.

We used life cycle assessment to model the environmental and financial costs of different scenarios of replacing reusable anaesthetic equipment with single-use variants. The primary environmental costs were CO 2 emissions (in CO 2 equivalents) and water use (in litres). We compared energy source mixes between Australia, the UK/Europe, and the USA.

RESULTS.

For an Australian hospital with six operating rooms, the annual financial cost of converting from single-use equipment to reusable anaesthetic equipment would be an AUD$32 033 (£19 220), 46% decrease. In Australia, converting from single-use to reusable equipment would result in an increase of CO 2 emissions from 5095 (95% CI: 4614-5658) to 5575 kg CO 2 eq (95% CI: 5542-5608), a 480 kg CO 2 eq (9%) increase. Using the UK/European power mix, converting from single-use (5575 kg CO 2 eq) to reusable anaesthetic equipment (802 kg CO 2 eq) would result in an 84% reduction (4873 kg CO 2 eq) in CO 2 emissions, whilst in the USA converting to reusables would have led to a 2427 kg CO 2 eq (48%) reduction. In Australia, converting from single-use to reusable equipment would more than double water use from 34.4 to 90.6 kilolitres.

CONCLUSIONS.

For an Australian hospital with six operating rooms, converting from single-use to reusable anaesthetic equipment saved more than AUD$30 000 (£18 000) per annum, but increased the CO 2 emissions by almost 10%. The CO 2 offset is highly dependent on the power source mix, while water consumption is greater for reusable equipment.

A randomised controlled trial of peri-operative lidocaine infusions for open radical prostatectomy

We allocated 76 men scheduled for radical retropubic prostatectomy to peri‐operative lidocaine 2% or saline 0.9%: a pre‐operative 0.075 ml.kg⁻¹ intravenous bolus; an intra‐operative intravenous infusion at 0.075 ml.kg⁻¹.h⁻¹; and 24 hours' postoperative subcutaneous infusion at 0.075 ml.kg⁻¹.h⁻¹. Lidocaine reduced the postoperative hospital stay by a mean (95% CI) of 1.3 (0.3–2.4) days, p = 0.017, from a mean (SD) of 4.6 (3.2) days with saline. Lidocaine reduced pain at rest during the first 24 postoperative hours by a mean (95% CI) of 1.8 (0.7–2.9) mm.h⁻¹, p = 0.001. Lidocaine reduced 24‐h morphine consumption by a mean (95% CI) of 13.9 (2.2–25.7) mg, p = 0.021, from a mean (SD) of 52.3 (26.9) mg with saline. There were no differences in other outcomes.

The effects of plasmalyte-148 vs. Hartmann's solution during major liver resection: a multicentre, double-blind, randomized controlled trial

BACKGROUND

The acid-base, biochemical and hematological effects of crystalloid solutions have not been comprehensively evaluated in patients with liver resection.

DESIGN

multicenter, prospective, double-blind randomized controlled trial investigating the biochemical effects of Hartmann's solution (HS) or Plasmalyte-148 (PL) in 60 patients undergoing major liver resection.

PRIMARY OUTCOME

base excess immediately after surgery.

SECONDARY OUTCOMES

changes in blood biochemistry and hematology.

RESULTS

At completion of surgery, patients receiving HS had equivalent mean standard base excess (-1.7±2.2 vs. -0.9±2.3 meq/L; P=0.17) to those treated with PL. However, patients treated with HS were more hyperchloremic (difference 1.7 mmol/L, 95% CI: 0.2 to 3.2, P=0.03) and hyperlactatemic (difference 0.8 mmol/L, 95% CI: 0.2 to 1.3; P=0.01). In contrast, patients receiving PL had higher mean plasma magnesium levels and lower ionized calcium levels. There were no significant differences in pH, bicarbonate, albumin and phosphate levels. Immediately after surgery, mean PT and aPTT were significantly lower in the PL group. Intraoperatively, the median (IQR) blood loss in the PL group was 300 mL (200:413) vs. 500 mL (300:638) in the HS group (P=0.03). Correspondingly, the postoperative hemoglobin was higher in the PL group. Total complications were more frequent in the HS Group (56% vs. 20%, relative risk 2.8; 95% CI: 1.3 to 6.1; P=0.007).

CONCLUSION

In liver resection patients, HS and PL led to similar base excess values but different post operative plasma biochemistry and hematology values. Understanding of these effects may help clinicians individualize fluid therapy in these patients.

Strong ion and weak acid analysis in severe preeclampsia: potential clinical significance

BACKGROUND

The influence of common disturbances seen in preeclampsia, such as changes in strong ions and weak acids (particularly albumin) on acid-base status, has not been fully elucidated. The aims of this study were to provide a comprehensive acid-base analysis in severe preeclampsia and to identify potential new biological predictors of disease severity.

METHODS

Fifty women with severe preeclampsia, 25 healthy non-pregnant- and 46 healthy pregnant controls (26-40 weeks' gestation), were enrolled in this prospective case-control study. Acid-base analysis was performed by applying the physicochemical approach of Stewart and Gilfix.

RESULTS

Mean [sd] base excess was similar in preeclamptic- and healthy pregnant women (-3.3 [2.3], and -2.8 [1.5] mEq/L respectively). In preeclampsia, there were greater offsetting contributions to the base excess, in the form of hyperchloraemia (BE(Cl) -2 [2.3] vs -0.4 [2.3] mEq/L, P<0.001) and hypoalbuminaemia (BE(Alb) 3.6 [1] vs 2.1 [0.8] mEq/L, P<0.001). In preeclampsia, hypoalbuminaemic metabolic alkalosis was associated with a non-reassuring/abnormal fetal heart tracing (P<0.001). Quantitative analysis in healthy pregnancy revealed respiratory and hypoalbuminaemic alkalosis that was metabolically offset by acidosis, secondary to unmeasured anions and dilution.

CONCLUSIONS

While the overall base excess in severe preeclampsia is similar to that in healthy pregnancy, preeclampsia is associated with a greater imbalance offsetting hypoalbuminaemic alkalosis and hyperchloraemic acidosis. Rather than the absolute value of base excess, the magnitude of these opposing contributors may be a better indicator of the severity of this disease. Hypoalbuminaemic alkalosis may also be a predictor of fetal compromise.

CLINICAL TRIAL REGISTRATION

clinicaltrials.gov: NCT 02164370.

Markers of coagulation activation after hepatic resection for cancer: evidence of sustained upregulation of coagulation

We investigated the possibility that despite postoperative derangements of routine laboratory coagulation tests, markers of coagulation activation and thrombin generation would be normal or increased in patients undergoing hepatic resection for cancer In addition to the conventional coagulation tests prothrombin time and activated partial thromboplastin time, we measured select markers of coagulation activation prothrombin fragments 1 and 2 (PF1 + 2), thrombin-antithrombin complexes and plasma von Willebrand Factor antigen in 21 patients undergoing hepatic resection. The impact of hepatic resection on coagulation and fibrinolysis was studied with thromboelastography. Preoperatively, routine laboratory coagulation and liver function tests were normal in all patients. On the first postoperative day, prothrombin time was prolonged (range 16 to 22 seconds) in eight patients (38%). For these patients, thromboelastography was normal in six (75%), PF1 + 2 was elevated in four (50%), and thrombin-antithrombin complexes and von Willebrand Factor antigen were elevated in all, which was evidence of acute phase reaction, sustained coagulation factor turnover and activation. By the fifth postoperative day, despite normalisation of prothrombin time, markers of increased coagulation activity remained greater than 85% of baseline values. The findings indicate that in patients undergoing liver resection for cancer, there is significant and prolonged postoperative activation of the haemostatic system despite routine coagulation tests being normal or even prolonged. Before considering therapeutic interventions an integrated approach to interpreting haematological data with clinical correlation is essential.

Pharmacoeconomics of Volatile Inhalational Anaesthetic Agents: An 11-Year Retrospective Analysis

With continuously increasing expenditure on health care resources, various cost containment strategies have been suggested in regard to controlling the cost of inhalational anaesthetic agents. We performed a cost identification analysis assessing inhalational anaesthetic agent expenditure at a tertiary level hospital, along with an evaluation of strategies to contain the cost of these agents.

The number of bottles of isoflurane, sevoflurane and desflurane used during the financial years 1997 to 2007 was retrospectively determined and the acquisition costs and cumulative drug expenditure calculated. Pharmacoeconomic modelling using low fresh gas flow anaesthesia was performed to evaluate practical methods of cost reduction.

The use of isoflurane decreased from 384 bottles during 1997 to 204 in 2007. In contrast, use of sevoflurane increased from 226 bottles during 1998 to 875 during 2007. Desflurane use increased from 34 bottles per year during 2002 (its year of introduction) to 163 bottles per year in 2007. While the inflation-adjusted cumulative expenditure for these inhalational agents (Australian dollars) increased from $132,000 in 1997 to over $326,000 in 2007, an increase of 168%, patient workload over the same period increased by only 11%. Pharmacoeconomic modelling demonstrated that sevoflurane at 2 l/minute costs 19 times more than isoflurane at 0.5 l/minute.

For the financial years 1997 to 2007, we found a progressive shift from the cheaper isoflurane to the more expensive agents, sevoflurane and desflurane, a shift associated with marked increases in costs. Low flow anaesthesia with isoflurane is one strategy to reduce costs.

What are we Telling Our Patients? A Survey of Risk Disclosure for Anaesthesia in Australia and New Zealand

The aim of our study was to determine the range of risks disclosed in four commonly-encountered clinical scenarios: knee arthroscopy, lumbar laminectomy, laparoscopic appendicectomy and laparotomy, and then to determine how often five commonly-disclosed risks were disclosed for each scenario. We conducted a pilot survey of consultant anaesthetists in the Auckland City Hospital, the Royal Melbourne Hospital and the Austin Hospital (response rate 59%). A web survey was then sent to 500 randomly-selected Australian and New Zealand College of Anaesthetists Fellows (response rate 29%). In the pilot survey, a wide range of risks were disclosed: five (range 0 to 13) for knee arthroscopy, seven (0 to 16) for lumbar laminectomy, six (0 to 13) for appendicectomy and nine (0 to 24) for laparotomy. In the web survey, the disclosure rates for all risks varied widely from “rarely” to “always”. Respondents were more likely to disclose risks infrequently if they were male (odds ratio 5.7, P=0.002) or exclusively in private practice (odds ratio 4.1, P=0.02). Age >45 years was not associated with disclosure frequency (odds ratio 1.65, P=0.23).

While the low response rate limits the validity and generalisability of many of our findings, we can nevertheless confidently conclude that risk disclosure varies widely in Australia and New Zealand. This large variation should be of concern to all anaesthetists. More work is needed to understand the reasons for this variation, and to develop a stronger consensus among anaesthetists about what risks should be disclosed.

Anaesthetic Aspects of Implanting Diaphragmatic Pacing in Patients with Spinal Cord Injury

Some patients with high cervical spinal cord injury are largely or completely dependent on mechanical ventilator support. Diaphragmatic phrenic nerve pacing is a new technique that offers some patients greater independence from mechanical ventilation. In selected patients, electrodes are placed on the abdominal side of the diaphragm via laparoscopy. An external pacing box provides the pacing stimulus. We report our experience with four patients with spinal cord injury in a pilot project, presenting for laparoscopic insertion of diaphragmatic phrenic nerve pacing leads inserted. The surgery took about two hours and diaphragmatic mapping precluded muscle relaxants. We used desflurane with remifentanil for maintenance. Apart from transferring the patients to and from their usual ventilators, other anaesthesia issues were difficult venous and arterial access for lines and long-term tracheostomies with no cuff or cuffs filled with water. While hypotension was a frequent problem, one patient also developed intraoperative hypertension secondary to autonomic dysreflexia. Preoperative testing predicted pacing outcome with three of the four patients having successful pacing with tidal volumes of up to 10 ml/kg at the end of surgery. This initial Australian experience may lead to greater use of the technique.

The financial and environmental costs of reusable and single-use plastic anaesthetic drug trays

We modelled the financial and environmental costs of two commonly used anaesthetic plastic drug trays. We proposed that, compared with single-use trays, reusable trays are less expensive, consume less water and produce less carbon dioxide, and that routinely adding cotton and paper increases financial and environmental costs. We used life cycle assessment to model the financial and environmental costs of reusable and single-use trays. From our life cycle assessment modelling, the reusable tray cost (Australian dollars) $0.23 (95% confidence interval [CI] $0.21 to $0.25) while the single-use tray alone cost $0.47 (price range of $0.42 to $0.52) and the single-use tray with cotton and gauze added was $0.90 (no price range in Melbourne). Production of CO2 was 110 g CO2 (95% CI 98 to 122 g CO2) for the reusable tray, 126 g (95% CI 104 to 151 g) for single-use trays alone (mean difference of 16 g, 95% CI -8 to 40 g) and 204 g CO2 (95% CI 166 to 268 g CO2) for the single-use trays with cotton and paper Water use was 3.1 l (95% CI 2.5 to 3.7 l) for the reusable tray, 10.4 l (95% CI 8.2 to 12.7 l) for the single-use tray and 26.7 l (95% CI 20.5 to 35.4 l) for the single-use tray with cotton and paper Compared with reusable plastic trays, single-use trays alone cost twice as much, produced 15% more CO2 and consumed three times the amount of water Packaging cotton gauze and paper with single-use trays markedly increased the financial, energy and water costs. On both financial and environmental grounds it appears difficult to justify the use of single-use drug trays.

Interpleural analgesia for attenuation of postoperative pain after hepatic resection

SUMMARY

We performed a prospective randomised trial to evaluate the analgesic efficacy of interpleural analgesia in patients undergoing hepatic resection. The control group (n = 25) received multimodal analgesia with intravenous morphine patient-controlled analgesia; in addition, the interventional group (n = 25) received interpleural analgesia with a 20-ml loading dose of levo bupivacaine 0.5% followed by a continuous infusion of levobupivacaine 0.125%. Outcome measures included pain intensity on movement using a visual analogue scale over 24 h, cumulative morphine and rescue analgesia requirements, patient satisfaction, hospital stay and all adverse events. Patients in the interpleural group were less sedated and none required treatment for respiratory depression compared to 6 (24%) in the control group (p< 0.01). Patients in the interpleural group also had lower pain scores during movement in the first 24 h. Patients' satisfaction, opioid requirements and duration of hospital stay were similar. We conclude that continuous interpleural analgesia augments intravenous morphine analgesia, decreases postoperative sedation and reduces respiratory depression after hepatic resection.

Boosting enrollment in neurology trials with Local Identification and Outreach Networks (LIONs)

OBJECTIVE

Our purpose was to develop a geographically localized, multi-institution strategy for improving enrolment in a trial of secondary stroke prevention.

METHODS

We invited 11 Connecticut hospitals to participate in a project named the Local Identification and Outreach Network (LION). Each hospital provided the names of patients with stroke or TIA, identified from electronic admission or discharge logs, to researchers at a central coordinating center. After obtaining permission from personal physicians, researchers contacted each patient to describe the study, screen for eligibility, and set up a home visit for consent. Researchers traveled throughout the state to enroll and follow participants. Outside the LION, investigators identified trial participants using conventional recruitment strategies. We compared recruitment success for the LION and other sites using data from January 1, 2005, through June 30, 2007.

RESULTS

The average monthly randomization rate from the LION was 4.0 participants, compared with 0.46 at 104 other Insulin Resistance Intervention after Stroke (IRIS) sites. The LION randomized on average 1.52/1,000 beds/month, compared with 0.76/1,000 beds/month at other IRIS sites (p = 0.03). The average cost to randomize and follow one participant was $8,697 for the LION, compared with $7,198 for other sites.

CONCLUSION

A geographically based network of institutions, served by a central coordinating center, randomized substantially more patients per month compared with sites outside of the network. The high enrollment rate was a result of surveillance at multiple institutions and greater productivity at each institution. Although the cost per patient was higher for the network, compared with nonnetwork sites, cost savings could result from more rapid completion of research.

Nurses' attitudes to a medical emergency team service in a teaching hospital

BACKGROUND

Cultural barriers including allegiance to traditional models of ward care and fear of criticism may restrict use of a medical emergency team (MET) service, particularly by nursing staff. A 1-year preparation and education programme was undertaken before implementing the MET at the Austin Hospital, Melbourne, Australia. During the 4 years after introduction of the MET, the programme has continued to inform staff of the benefits of the MET and to overcome barriers restricting its use.

OBJECTIVE

To assess whether nurses value the MET service and to determine whether barriers to calling the MET exist in a 400-bed teaching hospital.

METHODS

Immediately before hand-over of ward nursing, we conducted a modified personal interview, using a 17-item Likert agreement scale questionnaire.

RESULTS

We created a sample of 351 ward nurses and obtained a 100% response rate. This represents 50.9% of the 689 ward nurses employed at the hospital. Most nurses felt that the MET prevented cardiac arrests (91%) and helped manage unwell patients (97%). Few nurses suggested that they restricted MET calls because they feared criticism of their patient care (2%) or criticism that the patient was not sufficiently unwell to need a MET call (10%). 19% of the respondents indicated that MET calls are required because medical management by the doctors has been inadequate; many ascribed this to junior doctors and a lack of knowledge and experience. Despite hospital MET protocol, 72% of nurses suggested that they would call the covering doctor before the MET for a sick ward patient. However, 81% indicated that they would activate the MET if they were unable to contact the covering doctor. In line with hospital MET protocol, 56% suggested that they would make a MET call for a patient they were worried about even if the patient's vital signs were normal. Further, 62% indicated that they would call the MET for a patient who fulfilled MET physiological criteria but did not look unwell.

CONCLUSIONS

Nurses in the Austin Hospital value the MET service and appreciate its potential benefits. The major barrier to calling the MET appears to be allegiance to the traditional approach of initially calling parent medical unit doctors, rather than fear of criticism for calling the MET service. A further barrier seems to be underestimation of the clinical significance of the physiological perturbations associated with the presence of MET call criteria.

Spatial learning deficits and emotional impairments in pentylenetetrazole-kindled rats

Pentylenetetrazole (PTZ) is a chemical kindling agent used to examine the efficacy of potential anticonvulsants in rats. However, the extent to which PTZ mimics postseizure symptoms of epilepsy has not been thoroughly examined. This study assessed whether PTZ-induced seizures produce cognitive and emotional deficits that mimic those observed in many epileptic patients. Rats were given 30mg/kg PTZ or vehicle (intraperitoneally) every other day for 28 days. Those rats exhibiting consistent seizure activity were tested for learning ability and emotional reactivity, beginning 1 week following a single challenge dose of PTZ. Rats given PTZ made more reference memory errors in a radial arm water maze task, and exhibited emotional abnormalities in the forced swim test, the systematic handling test, and the open-field exploratory maze. Histological analysis revealed neuronal loss in the CA1 area and increased mossy fiber sprouting in the dentate gyrus, similar to what is observed in human epilepsy. These results indicate that PTZ kindling provides a useful model of postseizure dysfunction, which can serve as a screen for potential treatments for those cognitive, emotional, and neuropathological deficits that resemble those symptoms observed in human epilepsy.

Role of pump prime in the etiology and pathogenesis of cardiopulmonary bypass-associated acidosis

BACKGROUND

The development of metabolic acidosis during cardiopulmonary bypass (CPB) is well recognized but poorly understood. The authors hypothesized that the delivery of pump prime fluids is primarily responsible for its development. Accordingly, acid-base changes induced by the establishment of CPB were studied using two types of priming fluid (Haemaccel, a polygeline solution, and Ringer's Injection vs. Plasmalyte 148) using quantitative biophysical methods.

METHODS

A prospective, double-blind, randomized trial was conducted at a tertiary institution with 22 patients undergoing CPB for coronary artery bypass surgery. Sampling of arterial blood was performed at three time intervals: before CPB (t1), 2 min after initiation of CPB at full flows (t2), and at the end of the case (t3). Measurements of Na+, K+, Mg2+, Cl-, HCO3-, phosphate, Ca2+, albumin, lactate, and arterial blood gases at each collection point were performed. Results were analyzed in a quantitative manner.

RESULTS

Immediately on delivery of pump prime fluids, all patients developed a metabolic acidosis (base excess: 0. 95 mEq/l (t1) to -3.65 mEq/l (t2) (P < 0.001) for Haemaccel-Ringer's and 1.17 mEq/l (t1) to -3.20 mEq/l (t2). The decrease in base excess was the same for both primes (-4.60 vs. -4.37; not significant). However, the mechanism of metabolic acidosis was different. With the Haemaccel-Ringer's prime, the metabolic acidosis was hyperchloremic (Delta Cl-, +9.50 mEq/l; confidence interval, 7.00-11.50). With Plasmalyte 148, the acidosis was induced by an increase in unmeasured anions, most probably acetate and gluconate. The resolution of these two processes was different because the excretion of chloride was slower than that of the unmeasured anions (Delta base excess from t1 to t3 = -1.60 for Haemaccel-Ringer's vs. +1.15 for Plasmalyte 148; P = 0.0062).

CONCLUSIONS

Cardiopulmonary bypass-induced metabolic acidosis appears to be iatrogenic in nature and derived from the effect of pump prime fluid on acid-base balance. The extent of such acidosis and its duration varies according to the type of pump prime.