Tertiary Survey in the Days of Modern Imaging: Assessing the Detection Rate of Clinically Significant Injuries on Tertiary Survey in a Level 2 Trauma Centre.

AIM: To determine the utility of tertiary survey (TS) in patients subjected to whole-body CT (WBCT) or selective CT (SCT) following trauma. METHODS: A retrospective analysis was performed on trauma patients admitted to a level 2 trauma centre following the introduction of a standardised TS form in 2017. The initial imaging protocol (WBCT versus selective CT versus x-ray), subsequently requested imaging, standardised injury data, and length of stay (LOS) were recorded. Clinically significant injuries were defined as those with an Injury Severity Score (ISS) of 1 on the Abbreviated Injury Scale (AIS). RESULTS: Five hundred and seven patients were included. The rate of additional significant injuries at the time of TS was 1.18% (n=6), each requiring conservative management only. There was no significant difference in injury detection based on the initial imaging protocol; however, there were three near-misses identified. Of these patients, two underwent selective CT and one was subjected to a plain film series, with clinically significant injuries identified early upon completion of trauma imaging. Overall, 2.9% (n=15) of patients had completed trauma imaging during the same admission. WBCT was associated with higher ISS and length of stay (p<0.05). After controlling for ISS, there was no difference in length of stay between imaging modalities except in those patients with an ISS of 0 (no clinically significant injuries), who appeared to have longer admissions if subject to WBCT (p<0.001). CONCLUSION: The rate of missed injuries identified at TS is low. The imaging modality did not alter this. This may allow for the omission of the tertiary survey and earlier discharge in many trauma patients.

Multiple interventions with prolonged length of stay are required for treatment of necrotizing pancreatitis.

BACKGROUND: A proportion of patients with acute pancreatitis (AP) develop necrosis. Around a third will become infected, and this is associated with a significant requirement for intervention and support. We evaluated the burden of necrotizing pancreatitis (NP) in an Australian tertiary hospital with regards to morbidity, mortality and resource consumption. METHODS: This is a retrospective case series of patients with AP admitted for at least 5 days to identify those with NP between 2009 and 2014. Data were analysed in groups according to the determinant-based classification of AP severity. RESULTS: Of 1339 patients with AP, 546 stayed 5 days or longer, and 38 had necrosis. Overall mortality for those with necrosis was 10.5% (4/38). Infection complicated necrosis in 45% (17/38). Organ failure also occurred in 45% (17/38) of patients with necrosis. All patients in the critical category and severe category required admission to the intensive care unit for a median of 21 and 12 days, respectively. A total of 90% of patients with critical category disease developed multi-organ failure, whereas most with severe category disease developed single organ failure only. Overall length of stay increased with increasing severity of disease. Intervention was required in 82% of infected necrosis (median 4 procedures). Those without infection also required multiple radiological investigations (median 7). CONCLUSION: Necrosis is uncommon in our cohort but is associated with a significant health-care burden. Almost half the patients with necrosis develop organ failure requiring prolonged hospital and intensive care unit stay. Patients require multiple investigations and interventions for infected necrosis. NP remains a costly, morbid disease in our society.

A unifying view of synchronization for data assimilation in complex nonlinear networks.

Networks of nonlinear systems contain unknown parameters and dynamical degrees of freedom that may not be observable with existing instruments. From observable state variables, we want to estimate the connectivity of a model of such a network and determine the full state of the model at the termination of a temporal observation window during which measurements transfer information to a model of the network. The model state at the termination of a measurement window acts as an initial condition for predicting the future behavior of the network. This allows the validation (or invalidation) of the model as a representation of the dynamical processes producing the observations. Once the model has been tested against new data, it may be utilized as a predictor of responses to innovative stimuli or forcing. We describe a general framework for the tasks involved in the "inverse" problem of determining properties of a model built to represent measured output from physical, biological, or other processes when the measurements are noisy, the model has errors, and the state of the model is unknown when measurements begin. This framework is called statistical data assimilation and is the best one can do in estimating model properties through the use of the conditional probability distributions of the model state variables, conditioned on observations. There is a very broad arena of applications of the methods described. These include numerical weather prediction, properties of nonlinear electrical circuitry, and determining the biophysical properties of functional networks of neurons. Illustrative examples will be given of (1) estimating the connectivity among neurons with known dynamics in a network of unknown connectivity, and (2) estimating the biophysical properties of individual neurons in vitro taken from a functional network underlying vocalization in songbirds.

Assimilation of Biophysical Neuronal Dynamics in Neuromorphic VLSI.

Representing the biophysics of neuronal dynamics and behavior offers a principled analysis-by-synthesis approach toward understanding mechanisms of nervous system functions. We report on a set of procedures assimilating and emulating neurobiological data on a neuromorphic very large scale integrated (VLSI) circuit. The analog VLSI chip, NeuroDyn, features 384 digitally programmable parameters specifying for 4 generalized Hodgkin-Huxley neurons coupled through 12 conductance-based chemical synapses. The parameters also describe reversal potentials, maximal conductances, and spline regressed kinetic functions for ion channel gating variables. In one set of experiments, we assimilated membrane potential recorded from one of the neurons on the chip to the model structure upon which NeuroDyn was designed using the known current input sequence. We arrived at the programmed parameters except for model errors due to analog imperfections in the chip fabrication. In a related set of experiments, we replicated songbird individual neuron dynamics on NeuroDyn by estimating and configuring parameters extracted using data assimilation from intracellular neural recordings. Faithful emulation of detailed biophysical neural dynamics will enable the use of NeuroDyn as a tool to probe electrical and molecular properties of functional neural circuits. Neuroscience applications include studying the relationship between molecular properties of neurons and the emergence of different spike patterns or different brain behaviors. Clinical applications include studying and predicting effects of neuromodulators or neurodegenerative diseases on ion channel kinetics.

Nonlinear statistical data assimilation for HVC[Formula: see text] neurons in the avian song system.

With the goal of building a model of the HVC nucleus in the avian song system, we discuss in detail a model of HVC[Formula: see text] projection neurons comprised of a somatic compartment with fast Na[Formula: see text] and K[Formula: see text] currents and a dendritic compartment with slower Ca[Formula: see text] dynamics. We show this model qualitatively exhibits many observed electrophysiological behaviors. We then show in numerical procedures how one can design and analyze feasible laboratory experiments that allow the estimation of all of the many parameters and unmeasured dynamical variables, given observations of the somatic voltage [Formula: see text] alone. A key to this procedure is to initially estimate the slow dynamics associated with Ca, blocking the fast Na and K variations, and then with the Ca parameters fixed estimate the fast Na and K dynamics. This separation of time scales provides a numerically robust method for completing the full neuron model, and the efficacy of the method is tested by prediction when observations are complete. The simulation provides a framework for the slice preparation experiments and illustrates the use of data assimilation methods for the design of those experiments.

Quantitative study of voice dysfunction after thyroidectomy.

BACKGROUND: Up to 80% of patients without a recurrent laryngeal nerve palsy report alteration in their voice after a thyroid procedure. The aims of this study were (1) to quantify voice changes after thyroid operation; (2) to correlate the changes to the extent of operation; and (3) to correlate voice changes to intraoperative recurrent laryngeal nerve swelling. METHODS: Patients undergoing total and hemithyroidectomy were recruited prospectively from the Monash University Endocrine Surgery Unit during a 12-month period. Voice quality was scored subjectively using the Voice Disorder Index (score 0-40, from best to worst) and objectively using the Dysphonia Severity Index (score -5 to 5, from worst to best), before and after operation. These assessments were carried out by 2 speech pathologists. Recurrent laryngeal nerve diameter was measured intraoperatively at the commencement and conclusion of the lobectomy, using Vernier calipers with a resolution of 0.1 mm. Statistical methods used included Student t test, χ2, Wilcoxon signed-rank test, and linear regression. RESULTS: A total of 62 patients were included in the study, with a mean age of 48 ± 16 years and a female preponderance (6:1). Overall, the voice quality deteriorated both subjectively (mean Voice Disorder Index 4.2 ± 0.8-9.4 ± 1.2, P < .01) and objectively (mean Dysphonia Severity Index 3.9 ± 0.3-2.8 ± 0.3, P < .01) with thyroid operation. Patients who underwent either hemi- or total thyroidectomy both reported significant deterioration of voice (mean Voice Disorder Index 5.4 ± 1.5-7.9 ± 1.4, P = .02 and 3.4 ± 0.7-10.4 ± 1.8, P < .01 respectively). However, on objective assessment, only total thyroidectomy patients showed significant deterioration (Mean Dysphonia Severity Index 4.0 ± 0.3-2.5 ± 0.3, P < .01). At 6-12 months, both Voice Disorder Index and DSI returned to preoperative levels. Intraoperatively, the recurrent laryngeal nerve diameter increased by 0.58 ± 0.05 mm (1.82 ± 0.05 mm-2.40 ± 0.05 mm; P < .01). In hemithyroidectomy patients, the degree of nerve swelling correlated with the degree of deterioration in objective voice assessment, in that the greater the increase in recurrent laryngeal nerve diameter, the worse the Dysphonia Severity Index score (coefficient -0.4, P = .03). This was not the case in the total thyroidectomy patients. CONCLUSION: Voice quality deteriorates with thyroid operation despite functionally intact recurrent laryngeal nerve. While likely multifactorial, the degree of deterioration is related to the extent of operation and may also be related to the degree of recurrent laryngeal nerve swelling. Spontaneous resolution is expected in the majority of patients.

Perioperative complications in patients on low-molecular-weight heparin bridging therapy.

BACKGROUND: Patients taking warfarin are often given interim anticoagulation in the perioperative period. Institutional guidelines that use low-molecular-weight heparin (LMWH) 'bridging' while the international normalized ratio (INR) is sub-therapeutic are often based on the American College of Chest Physicians Anticoagulation Guidelines. PURPOSE: This study aims to identify if patients at a tertiary referral hospital were anticoagulated in line with these guidelines, and the incidence and nature of bleeding and thromboembolic complications. METHODS: A retrospective review of the Alfred Hospital General Surgical and 'Hospital at Home' databases was conducted, identifying patients who underwent elective general surgical procedures and received bridging anticoagulation with enoxaparin. Demographics, indication for anticoagulation, bleeding and thromboembolism rates were recorded. Thromboembolic risk was estimated. RESULTS: The study identified 108 patients. Three-quarters of all patients were anticoagulated with LMWH doses in accordance with the guidelines. Thirty of the 108 patients suffered bleeding complications. This group was younger, weighed less, received higher doses of enoxaparin and were at higher predicted risk of thromboembolism than non-bleeding patients. Wound haematoma, rectal bleeding and intra-abdominal bleeding were the most frequent complications. The peak time of bleeding was 3.5 days after surgery. Twelve patients returned to theatre, 13 were readmitted and 3 received blood transfusion. One patient suffered pulmonary emboli on the first post-operative day. CONCLUSION: LMWH bridging therapy when prescribed appropriately is associated with low rates of inpatient thromboembolism in elective general surgical patients within our institution, but an unexpectedly high rate of bleeding complications.

Parental satisfaction with paediatric care, triage and waiting times.

OBJECTIVE: The present study aims to determine parental and guardian's perceptions of paediatric emergency care and satisfaction with care, waiting times and triage category in a community ED. METHODS: A structured questionnaire was provided to parents or guardians of paediatric patients presenting to emergency. The survey evaluated parent perceptions of waiting time, environment/facilities, professionalism and communication skills of staff and overall satisfaction of care. RESULTS: One hundred and thirty-three completed questionnaires were received from parents of paediatric patients. Responses were overall positive with respect to the multiple domains assessed. Parents generally considered waiting times to be appropriate and consistent with triage categories. Overall satisfaction was not significantly different for varying treatment or waiting times. Patients triaged as semi-urgent were of the opinion that waiting times were less appropriate than urgent, less-urgent or non-urgent patients. CONCLUSION: On the basis of the present study, patient perceptions and overall satisfaction of care does not appear to be primarily influenced by time spent waiting or receiving treatment. Attempts made at the triage process to ensure that semi-urgent patients have reasonable expectations of waiting times might provide an opportunity to improve these patients' expectations and perceptions.