Predicting neurosurgical referral outcomes in patients with chronic subdural hematomas using machine learning algorithms - A multi-center feasibility study.

Background: Chronic subdural hematoma (CSDH) incidence and referral rates to neurosurgery are increasing. Accurate and automated evidence-based referral decision-support tools that can triage referrals are required. Our objective was to explore the feasibility of machine learning (ML) algorithms in predicting the outcome of a CSDH referral made to neurosurgery and to examine their reliability on external validation. Methods: Multicenter retrospective case series conducted from 2015 to 2020, analyzing all CSDH patient referrals at two neurosurgical centers in the United Kingdom. 10 independent predictor variables were analyzed to predict the binary outcome of either accepting (for surgical treatment) or rejecting the CSDH referral with the aim of conservative management. 5 ML algorithms were developed and externally tested to determine the most reliable model for deployment. Results: 1500 referrals in the internal cohort were analyzed, with 70% being rejected referrals. On a holdout set of 450 patients, the artificial neural network demonstrated an accuracy of 96.222% (94.444-97.778), an area under the receiver operating curve (AUC) of 0.951 (0.927-0.973) and a brier score loss of 0.037 (0.022-0.056). On a 1713 external validation patient cohort, the model demonstrated an AUC of 0.896 (0.878-0.912) and an accuracy of 92.294% (90.952-93.520). This model is publicly deployed: https://medmlanalytics.com/neural-analysis-model/. Conclusion: ML models can accurately predict referral outcomes and can potentially be used in clinical practice as CSDH referral decision making support tools. The growing demand in healthcare, combined with increasing digitization of health records raises the opportunity for ML algorithms to be used for decision making in complex clinical scenarios.

Universal ultracold collision rates for polar molecules of two alkali-metal atoms.

Universal collision rate constants are calculated for ultracold collisions of two like bosonic or fermionic heteronuclear alkali-metal dimers involving the species Li, Na, K, Rb, or Cs. Universal collisions are those for which the short range probability of a reactive or quenching collision is unity such that a collision removes a pair of molecules from the sample. In this case, the collision rates are determined by universal quantum dynamics at very long range compared to the chemical bond length. We calculate the universal rate constants for reaction of the reactive dimers in their ground vibrational state v = 0 and for vibrational quenching of non-reactive dimers with v ≥ 1. Using the known dipole moments and estimated van der Waals coefficients of each species, we calculate electric field dependent loss rate constants for collisions of molecules tightly confined to quasi-two-dimensional geometry by a one-dimensional optical lattice. A simple scaling relation of the quasi-two-dimensional loss rate constants with dipole strength, trap frequency and collision energy is given for like bosons or like fermions. It should be possible to stabilize ultracold dimers of any of these species against destructive collisions by confining them in a lattice and orienting them with an electric field of less than 20 kV cm(-1).

Development of a Spinal Cord Injury Model Permissive to Study the Cardiovascular Effects of Rehabilitation Approaches Designed to Induce Neuroplasticity.

As primary medical care for spinal cord injury (SCI) has improved over the last decades there are more individuals living with neurologically incomplete (vs. complete) cervical injuries. For these individuals, a number of promising therapies are being actively researched in pre-clinical settings that seek to strengthen the remaining spinal pathways with a view to improve motor function. To date, few, if any, of these interventions have been tested for their effectiveness to improve autonomic and cardiovascular (CV) function. As a first step to testing such therapies, we aimed to develop a model that has sufficient sparing of descending sympathetic pathways for these interventions to target yet induces robust CV impairment. Twenty-six Wistar rats were assigned to SCI (n = 13) or naïve (n = 13) groups. Animals were injured at the T3 spinal segment with 300 kdyn of force. Fourteen days post-SCI, left ventricular (LV) and arterial catheterization was performed to assess in vivo cardiac and hemodynamic function. Spinal cord lesion characteristics along with sparing in catecholaminergic and serotonergic projections were determined via immunohistochemistry. SCI produced a decrease in mean arterial pressure of 17 ± 3 mmHg (p < 0.001) and left ventricular contractility (end-systolic elastance) of 0.7 ± 0.1 mmHg/µL (p < 0.001). Our novel SCI model produced significant decreases in cardiac and hemodynamic function while preserving 33 ± 9% of white matter at the injury epicenter, which we believe makes it a useful pre-clinical model of SCI to study rehabilitation approaches designed to induce neuroplasticity.

The Economic Burden of Postoperative Complications Predicted by the Comprehensive Complication Index® in Patients Undergoing Elective Major Hepatopancreaticobiliary Surgery for Malignancy - A Prospective Cost Analysis.

BACKGROUND/AIM: Postoperative complications have a tremendous impact on in-hospital costs. The novel Comprehensive Complication Index® (CCI®) summarizes all complications together and is more sensitive than existing morbidity endpoints. The purpose of this study was to assess the correlation of CCI® with in-hospital costs and externally validate a novel cost prediction calculator. PATIENTS AND METHODS: This was a prospective study including consecutive patients undergoing elective major hepatopancreaticobiliary (HPB) surgery for malignancy at a London tertiary referral hospital. A priori sample size and post-hoc power calculations were performed. RESULTS: Thirty patients were included in the analysis, 14 were female, and the median age was 67 [interquartile range (IQR)=54-74] years. The median Charlson Comorbidity Index was 6 (IQR=5-8). Eighteen patients underwent liver, 9 pancreatic surgery and three a palliative bypass; 11 patients had a major complication (≥grade 3a) according to the Clavien-Dindo classification. The median CCI® was 30.2 (IQR=12.18-39.5). The mean cost per case was 13,908 (SD=4,600) GBP. There was no correlation between the Charlson Comorbidity Index or age with actual cost. However, there was very good correlation of actual cost with the CCI® (r=0.77, 95% confidence interval=0.57-0.89, p<0.001) as well as with the predicted cost (Clavien Cost Prediction Calculator) (r=0.70, 95% confidence interval=0.44-0.85, p<0.001). CONCLUSION: These findings support the hypothesis that complications are the most important predictor of overall cost in the setting of elective major HPB surgery for malignancy. Furthermore, CCI® and the novel Cost Prediction Calculator can be used in this setting to accurately predict costs using no additional resources.

Comparison of lipase and amylase for diagnosing post-operative pancreatic fistulae.

BACKGROUND: To ascertain if post-operative drain fluid lipase is superior to amylase in routinely detecting clinically significant post-operative pancreatic fistulae (POPF). METHOD: Between January 2015 and March 2016 data were collected on all patients undergoing pancreatic surgery at a regional referral centre. Routine drain fluid analysis was performed on post-operative patients as part of a locally defined enhanced recovery protocol. POPF was diagnosed in accordance with the recently updated International Study Group of Pancreatic Surgery guidance. RESULTS: During the study period, there were 68 pancreatic resections. The median age was 69.1 years. A total of 11 (15.9%) patients developed clinically significant POPF (nine type B and two type C). The median drain amylase result in patients with type B or C leak was 532 IU/L (interquartile range (IQR) 264-833). This was significantly higher than those without a clinical fistula (median 38, IQR 15-376, P = 0.012). The median drain lipase result was 1504 IU/L (IQR 746-2236). This was significantly higher than those without a clinical fistula (median 57, IQR 13-1277, P = 0.012). Fluid amylase had a sensitivity of 81.8% and specificity of 69.2%; fluid lipase had a sensitivity of 91% and specificity of 64.9%. CONCLUSION: Our experience suggests drain fluid amylase or lipase results are not sufficiently sensitive or specific to reassure clinicians and rule out clinically significant POPF. However, if biochemical tests are used to aid decision-making, then lipase is a more sensitive biochemical marker than amylase for the routine detection of clinically significant POPF.

Total parathyroidectomy in patients with chronic kidney disease: Avoiding repeat surgery.

Renal hyperparathyroidism (RHPT) is a common complication of renal failure and it is associated with significant morbidity and mortality. The aim of this study was to determine the patient characteristics which might predict persistent or recurrent hyperparathyroidism after surgery and to assess the long-term effect of unsuccessful surgery. This is a retrospective study of all chronic kidney disease patients who required a total parathyroidectomy (TP) because of failed medical management from January 1999 to December 2014. Patient characteristics, preoperative imaging, operative findings, and patient outcome were all studied. Differences between groups (dialysis-dependent and nondialysis-dependent; preoperative imaging and no imaging) were tested by the Chi-square statistic test and P <0.05 was regarded statistically significant. Eighty-eight patients underwent TP during this period and were followed up for a median of 35.5 months (range 1-119 months). Seventy (80%) had removal of all parathyroid glands with associated fall in parathyroid hormone level. There were no statistically significant differences in surgical success rates in neither the dialysis-dependent versus nondialysis-dependent groups nor the preoperative imaging versus no imaging groups. Two patients underwent repeat parathyroid surgery for persistent hyperparathyroidism and 16 were followed up without surgery. Preoperative imaging did not direct surgical management nor reduce surgical failure rate in this series. The long-term effects of pharmaceutical developments in this area are unknown but are likely to change indications for initial parathyroidectomy and reoperation. An agreed protocol is essential for the management of patients with RHPT.

Incidence of post-ERCP pancreatitis from direct pancreatic juice collection in hereditary pancreatitis and familial pancreatic cancer before and after the introduction of prophylactic pancreatic stents and rectal diclofenac.

OBJECTIVES: Individuals from hereditary pancreatitis (HP) and familial pancreatic cancer (FPC) kindreds are at increased risk of developing pancreatic cancer. Premalignant molecular changes may be detected in pancreatic juice collected by endoscopic retrograde cholangiopancreatography (ERCP). The objective was to determine the risk of post-ERCP pancreatitis (PEP). METHODS: A prospective study (1999-2013) was undertaken of 80 ERCPs (24 in HP and 56 in FPC) from 60 individuals and the impact of PEP prophylaxis using a self-expelling pancreatic stent and 50 mg diclofenac per rectum from 2008. RESULTS: There was no PEP in the HP cohort and 13 (23.2%) PEP from 56 procedures in the FPC cohort (P = 0.0077). Up to 2008 PEP had occurred in 7 (43.8%) of 16 procedures in FPC individuals versus none of 18 procedures in HP individuals (P = 0.0021). After the introduction of prophylaxis, the incidence of PEP fell to 6 (15.0%) of 40 procedures in FPC individuals (P = 0.0347).The odds ratio (95% confidence interval) was 0.23 (0.06-0.84) in favor of prophylaxis (0.035). CONCLUSIONS: Individuals with HP are at minimal risk for PEP. Although the risk of PEP in individuals with FPC can be reduced by using prophylactic self-expelling stents and diclofenac, it remains too high for routine screening.

Resonant control of polar molecules in individual sites of an optical lattice.

We study the resonant control of two nonreactive polar molecules in an optical lattice site, focusing on the example of RbCs. Collisional control can be achieved by tuning bound states of the intermolecular dipolar potential by varying the applied electric field or trap frequency. We consider a wide range of electric fields and trapping geometries, showing that a three-dimensional optical lattice allows significantly wider avoided crossings than free space or quasi-two dimensional geometries. Furthermore, we find that dipolar confinement-induced resonances can be created with reasonable trapping frequencies and electric fields, and have widths that will enable useful control in forthcoming experiments.

Urinary tract infection mimicking acute mesenteric ischaemia in an immunocompromised patient.

Bowel infarction due to acute mesenteric ischaemia (AMI) is an abdominal emergency with a high mortality rate. We report a case of exaggerated septic response to a urinary tract infection mimicking AMI in an immunosuppressed diabetic patient. A 56-year-old female was found collapsed at home with a 24 hour history of diarrhoea, a central abdominal pain and a complex past medical history. Examination showed her to be pyrexial, drowsy, profoundly dehydrated with evidence of cardiovascular collapse. She had a tender distended abdomen, raised inflammatory markers, raised lactate of 9.1 u/L and urinalysis was positive for leucocytes and nitrites. An abdominal computed tomography (CT) scan was reported to show small bowel ischaemia. She underwent a negative laparotomy and recovered following management in the intensive therapy unit. The negative laparotomy rate can be reduced by having abdominal CT performed and reported by an experienced radiologist or by the use of diagnostic laparoscopy.

Acute presentation of intestinal malrotation in adults: a report of two cases.

INTRODUCTION: Intestinal malrotation is a rare developmental abnormality occurring as a result of incomplete rotation during fetal life. It usually presents in the first few weeks of life, but may persist unrecognised into adult life. We report two interesting cases in elderly patients both characterised by a significant diagnostic challenge due to atypical clinical and radiological signs and in one case an unusual complication following laparotomy. CASE REPORTS: The first case was a 64-year-old man initially treated for diverticulitis but at laparotomy was found to have malrotation of the midgut and a perforated left-sided appendicitis. The second case was a 76-year-old woman admitted with multiple fractures and increasing abdominal distension following a fall. Ten days after admission, she underwent right hemicolectomy to treat faecal peritonitis due to multiple caecal perforations complicating volvulus in the presence of midgut malrotation. CONCLUSIONS: These cases illustrate challenges associated with managing patients with undiagnosed intestinal malrotation. Delayed diagnosis is a common feature in several case reports describing atypical presentation of appendicitis in patients with malrotation. While abdominal CT scan can remove much of the diagnostic uncertainty, the diagnosis of malrotation can be missed unless there is a high index of suspicion.