Total knee arthroplasty component templating: a predictive model

Preoperative planning is essential to total knee arthroplasty (TKA); however, TKA templating is historically inaccurate. To improve on templating accuracy and streamline preoperative planning, we set out to predict component sizes based on patient characteristics without radiographs. A total of 123 consecutive patients undergoing unilateral TKA were identified and included in the model study. Input variables consisted of age, gender (as a binary number), height, weight, and body mass index. A linear regression model was created. The models predicted component size exactly in 74% of femurs and 85% of tibias. All model predictions were within a ±1 size of the actual components implanted. Our models were more accurate than any previous model for TKA reported.     

Occam's razor: Intervene early to prevent more strokes!

The early risk of stroke after a patient suffers a transient ischemic attack (TIA)/minor stroke is significantly higher than previously thought. In most health systems, this (unfortunately) means that many vulnerable patients will have suffered their stroke before having had any chance of being considered for carotid endarterectomy (CEA) or carotid angioplasty with stenting (CAS). The problem is then compounded by institutional delays in finally undertaking CEA/CAS, which leads to even greater diminishing benefit to the patient. Notwithstanding the fact that the international trials used a 6-month threshold for inclusion, it remains an unpalatable fact that if CEA/CAS is delayed beyond 12 weeks in symptomatic patients with North American Symptomatic Carotid Endarterectomy Trial (NASCET) 50% to 99% stenoses, the patient is exposed to all of the risks of intervening, but gains little in the way of long-term stroke prevention. The take-home message is, therefore, very simple; "intervene early to prevent more strokes". Occam's razor has never been sharper!     

Development and validation of a predictive model for acute kidney injury in patients with moderately severe and severe acute pancreatitis

Clinical and Experimental Nephrology - Acute kidney injury is a serious complication of moderately severe and severe acute pancreatitis, which significantly increases mortality. There are currently...     

Assessing the utility of a prognostication model to predict 1-year mortality in patients undergoing radiation therapy for spinal metastases

Background Context

Predicting survival outcomes after radiation therapy (RT) alone for metastatic disease of the spine is a challenging task that is important to guiding treatment decisions (eg, determining dose fractionation and intensity). The New England Spinal Metastasis Score (NESMS) was recently introduced and validated in independent cohorts as a tool to predict 1-year survival following surgery for spinal metastases. This metric is composed of three factors: preoperative albumin, ambulatory status, and modified Bauer score, with the total score ranging from 0 to 3.

A novel hybrid model predictive control design with application to a quadrotor helicopter

In this paper, a novel control design strategy based on a hybrid model predictive control in combination with fuzzy logic control is presented for a quadrotor helicopter system. In the proposed scheme, a 2‐part control structure is used. In the first part, a linear model predictive controller with receding horizon design strategy is combined with a nonlinear model predictive controller, which is applied as the main controller. In the second part, a 2‐level fuzzy logic controller is utilized to assist the first controller when the error exceeds a predefined value. The proposed nonlinear predictive control method utilizes a novel approach in which a prediction of the future outputs is used in the modeling stage. Using this simple technique, the problem can be solved using linear methods and, thereby, due to considerable reduction in the computational cost, it will be applicable for the systems with fast dynamics. Moreover, the fuzzy logic controller is used as a supervisor to adjust a proportional‐integral‐derivative controller to enhance the system performance by decreasing the tracking error. The proposed scheme is applied to a model of quadrotor system such that the difference between the predicted output of the system and the reference value is minimized while there are some constraints on inputs and outputs of the nonlinear quadrotor system. Simulation results demonstrate the efficiency of the proposed control scheme for the quadrotor system model.     

Applying a cognitive‐emotional model to nonsuicidal self‐injury

The recently proposed cognitive‐emotional model of nonsuicidal self‐injury (NSSI) draws on emotion regulation models and social cognitive theory to understand the onset, maintenance, and cessation of NSSI. We tested the prediction of the model that the relationship between emotional reactivity and NSSI is moderated by specific cognitions about self‐injury (i.e., self‐efficacy to resist NSSI, NSSI outcome expectancies), emotion regulation, and rumination. A sample of 647 university students aged 17–25 years (M = 19.92, SD = 1.78) completed self‐report measures of the constructs of interest. As expected, we found that emotional reactivity was positively related to NSSI, particularly for people who had weak self‐efficacy to resist NSSI. However, emotional reactivity was negatively related to NSSI for people who were more likely to use expressive suppression to regulate emotion. Implications for the theoretical understanding of NSSI are discussed.     

Creation of a model of chronic pancreatitis]

A model of chronic pancreatitis has been created in 13 mongrel dogs. The animals were withdrawn from the experiment 2 months after the beginning of it. According to the author's data, artifically created insufficiency of the constrictors of the common bile and pancreatic ducts in dogs is analogous to unfitness of the sphincter in man and results in the development of the changes in the abdominal cavity, specific for chronic pancreatitis.     

A model to study acute pancreatitis in the dog

An acute pancreatitis model was developed which was consistently lethal and which allowed assessment of the excretory function of the pancreas without catheterization of the pancreatic ducts. The minor pancreatic duct was ligated and cut, a modified Thomas cannula was inserted in the duodenum opposite the major pancreatic duct and exteriorized on the right ventrolateral abdominal wall. This allowed production of pancreatitis by retrograde injection of bile-trypsin mixture in the major duct. The minimum lethal dose of bile-trypsin mixture, as determined in 22 dogs, was 1.02 ml of bile/kg of body weight, containing 2000 units of trypsin in each 1 ml of bile used. Injection of this mixture into the major pancreatic duct resulted in severe damage to approximately 38% of the gland.A plastic sleeve was inserted into the cannula during collections of pancreatic juice, insolating the pancreatic duct from the intestine. Collection of pancreatic secretion could be accomplished without significant contamination by intestinal content and required minimum cooperation from the dog.     

Stochastic model predictive control approaches applied to drinking water networks

Control of drinking water networks is an arduous task, given their size and the presence of uncertainty in water demand. It is necessary to impose different constraints for ensuring a reliable water supply in the most economic and safe ways. To cope with uncertainty in system disturbances due to the stochastic water demand/consumption and optimize operational costs, this paper proposes three stochastic model predictive control (MPC) approaches, namely, chance‐constrained MPC, tree‐based MPC, and multiple‐scenario MPC. A comparative assessment of these approaches is performed when they are applied to real case studies, specifically, a sector and an aggregate version of the Barcelona drinking water network in Spain. Copyright © 2016 John Wiley & Sons, Ltd.     

Presymptomatic spondylotic cervical myelopathy: an updated predictive model

Spondylotic cervical cord compression detected by imaging methods is a prerequisite for the clinical diagnosis of spondylotic cervical myelopathy (SCM). Little is known about the spontaneous course and prognosis of clinically “silent” presymptomatic spondylotic cervical cord compression (P-SCCC). The aim of the present study was to update a previously published model predictive for the development of clinically symptomatic SCM, and to assess the early and late risks of this event in a larger cohort of P-SCCC subjects. A group of 199 patients (94 women, 105 men, median age 51 years) with magnetic resonance signs of spondylotic cervical cord compression, but without clear clinical signs of myelopathy, was followed prospectively for at least 2 years (range 2–12 years). Various demographic, clinical, imaging, and electrophysiological parameters were correlated with the time for the development of symptomatic SCM. Clinical evidence of the first signs and symptoms of SCM within the follow-up period was found in 45 patients (22.6%). The 25th percentile time to clinically manifested myelopathy was 48.4 months, and symptomatic SCM developed within 12 months in 16 patients (35.5%). The presence of symptomatic cervical radiculopathy and electrophysiological abnormalities of cervical cord dysfunction detected by somatosensory or motor-evoked potentials were associated with time-to-SCM development and early development (≤12 months) of SCM, while MRI hyperintensity predicted later (>12 months) progression to symptomatic SCM. The multivariate predictive model based on these variables correctly predicted early progression into SCM in 81.4% of the cases. In conclusion, electrophysiological abnormalities of cervical cord dysfunction together with clinical signs of cervical radiculopathy and MRI hyperintensity are useful predictors of early progression into symptomatic SCM in patients with P-SCCC. Electrophysiological evaluation of cervical cord dysfunction in patients with cervical radiculopathy or back pain is valuable. Meticulous follow-up is justified in high-risk P-SCCC cases.     

Severity scoring for prognostication in patients with severe acute pancreatitis: comparative analysis of the Ranson score and the APACHE III score

BACKGROUND: Despite a paucity of validation, the Ranson score is still the most popular method for gauging the severity of pancreatitis. HYPOTHESES: The Ranson score more accurately predicts outcomes in patients with severe acute pancreatitis (SAP) when compared with APACHE (Acute Physiology and Chronic Health Evaluation) III scores, and the individual components of the Ranson score differ in their capacities to predict outcome in patients with SAP. METHODS: Patients admitted with SAP to a university surgical intensive care unit (ICU) were studied prospectively. Each component and the total Ranson score were recorded. Also recorded were the APACHE II and III scores. These Ranson variables were compared using univariate analysis of variance for mortality, need for operative debridement, and need for an ICU stay for longer than 7 days. Significant variables were then analyzed by a multivariate analysis of variance to assess independent predictors of mortality, the need for debridement, and prolonged length of stay. Data are given as the mean +/- SEM. RESULTS: Seventy-six patients (21.1% mortality), aged 61.8 +/- 1.9 years, were studied. The mean APACHE III score was 48.2 +/- 3.3, and the mean ICU stay was 10.4 +/- 2.1 days. The number of positive Ranson variables was significantly higher in nonsurvivors compared with survivors (5.6 +/- 0.5 vs 3.4 +/- 0.2; P<.001), as were the APACHE III score (76.9 +/- 9.9 vs 40.5 +/- 2.5; P<.001) and ICU stay (24.9 +/- 7.5 vs 76.5 +/- 1.9 days; P =.002). Ranson variables that predicted mortality included values for blood urea nitrogen, calcium, base deficit, and fluid sequestration. CONCLUSIONS: The Ranson score remains a valid predictor of outcomes in patients with SAP, and individual Ranson variables determined 48 hours after hospital admission predicted adverse outcomes more accurately than early Ranson variables in patients with SAP.     

Gastric ultrasound in the third trimester of pregnancy: a randomised controlled trial to develop a predictive model of volume assessment

Bedside gastric ultrasonography can be performed reliably by anaesthetists to assess gastric content in the peri‐operative period. We aimed to study the relationship between gastric cross‐sectional area, assessed by ultrasound, and volumes of clear fluids ingested by pregnant women. We recruited 60 non‐labouring third‐trimester pregnant women in a randomised controlled and assessor‐blinded study. A standardised scanning protocol of the gastric antrum was performed in the 45° semirecumbent and 45° semirecumbent‐right lateral positions. Subjects were randomly allocated to drink one out of six predetermined volumes of apple juice (0 ml, 50 ml, 100 ml, 200 ml, 300 ml, 400 ml). Qualitative and quantitative assessments at a baseline period after an 8‐h fast, and immediately after the drink, were used to establish the correlation between antral cross‐sectional area and volume ingested. A predictive model to estimate gastric volume was developed. Antral cross‐sectional area in the semirecumbent right lateral position significantly correlated with the ingested volume (Spearman rank correlation = 0.7; p < 0.0001). A cut‐off value of 9.6 cm² discriminated ingested volumes ≥ 1.5 ml.kg^?1 with a sensitivity of 80%, a specificity of 66.7%, and an area under the curve of 0.82. A linear predictive model was developed for gastric volume based only on antral cross‐sectional area (Volume (ml) = ?327.1 + 215.2 × log (cross‐sectional area) (cm²)). We conclude that in pregnant women in the third trimester of gestation, the antral cross‐sectional area correlates well with volumes ingested, and this cut‐off value in the semirecumbent right lateral position discriminates high gastric volumes.     

Patient-Controlled Expansion: Applying a New Technique to Breast Reconstruction

Tissue expansion has been used as a technique to increase the amount of skin (and/or soft tissues) available for closing a defect or reconstructing an anatomic unit. Although the technique has undergone many modifications, the basic principles have remained more or less constant. The shortcomings of tissue expansion have remained unsolved for many years, namely, long periods of expansion with concomitant abnormal appearance with increased risk of complications over this extended period. Decreasing the expansion period would significantly contribute to patient convenience, decreased costs, and improved acceptance of the technique. This would need to be done within a background of safety without compromise to the reconstructive effort. With minor modification to the existing tissue expanders and their attachments together with modified patient-controlled infusion devices, a new method has been devised for tissue expansion in which the patient can control and expedite the entire process. As “proof of concept,” 10 patients were selected for this trial. All had undergone mastectomies without concomitant radiotherapy. Successful full expansion, beginning the day after surgery, was achieved in all cases in approximately 3 weeks with minimal complications. Patent pending design modifications have been made that expedite the process, making it easier, more efficient, and cheaper to achieve full expansion. Although the numbers in this series were small, proof of concept was achieved, and trials are ongoing with increasing numbers expected. The concept is applicable to all forms of tissue expansion, including aesthetic indications such as hair restoration, tubular breast correction, and the like.     

Local recurrence and the EEA stapler--examination of a predictive model

The overall local recurrence rate following resection of colorectal cancer with restoration of continuity with staples in Wellington was 24%. Nine of 11 patients with local recurrence following resection of rectal tumours had distant metastases at the time of diagnosis of their local recurrence. Using a predictive model to retrospectively estimate the probability of local recurrence it was found that nine of these 11 patients would have been expected to have had a lower local recurrence rate had they undergone abdominoperineal resection of the rectum initially. Since local recurrence is simply a local manifestation of systemic disease in 90% of patients, however, it is suggested that patients would prefer restoration of bowel continuity in preference to rectal excision and stoma formation, there being such little survival advantage for the latter procedure. The utility of the predictive model is therefore questioned.     

Surgical upgrade rate of breast atypia to malignancy: An academic center's experience and validation of a predictive model

Atypical ductal hyperplasia (ADH), atypical lobular hyperplasia (ALH), and lobular carcinoma in situ (LCIS) are commonly seen on breast core needle biopsy (CNB). Many institutions recommend excision of these lesions to exclude malignancy. A retrospective chart review was performed on patients who had ADH, ALH, or LCIS on breast CNB from 1/1/08 to 12/31/10 who subsequently had surgical excision of the biopsy site. Study objectives included determining upgrade to malignancy at surgical excision, identification of predictors of upgrade, and validation of a recently published predictive model. Clinical and demographic factors, pathology, characteristics of the biopsy procedure and visible residual lesion were recorded. T test and chi‐squared test were used to identify predictors. Classification tree was used to predict upgrade. 151 patients had mean age of 53 years. The mean maximum lesion size on imaging was 11 mm. The primary atypia was ADH in 63.6%, ALH in 27.8%, and LCIS in 8.6%. 16.6% of patients had upgrade to malignancy, with 72% DCIS and 28% invasive carcinoma. Risk factors for upgrade included maximum lesion size (P = .002) and radiographic presence of residual lesion (P = .001). A predictive model based on these factors had sensitivity 78%, specificity 80% and AUC = 0.88. Validating a published nomogram with our data produced accuracy figures (AUC = 0.65) within published CI of 0.63‐0.82. In CNB specimens containing ADH, ALH, or LCIS, initial lesion size and presence of residual lesion are predictors of upgrade to malignancy. A validated model may be helpful in developing patient management strategies.