Evaluation of machine learning models as decision aids for anesthesiologists.

Machine Learning (ML) models have been developed to predict perioperative clinical parameters. The objective of this study was to determine if ML models can serve as decision aids to improve anesthesiologists' prediction of peak intraoperative glucose values and postoperative opioid requirements. A web-based tool was used to present actual surgical case and patient information to 10 practicing anesthesiologists. They were asked to predict peak glucose levels and post-operative opioid requirements for 100 surgical patients with and without presenting ML model estimations of peak glucose and opioid requirements. The accuracies of the anesthesiologists' estimates with and without ML estimates as reference were compared. A questionnaire was also sent to the participating anesthesiologists to obtain their feedback on ML decision support. The accuracy of peak glucose level estimates by the anesthesiologists increased from 79.0 ± 13.7% without ML assistance to 84.7 ± 11.5% (< 0.001) when ML estimates were provided as reference. The accuracy of opioid requirement estimates increased from 18% without ML assistance to 42% (p < 0.001) when ML estimates were provided as reference. When ML estimates were provided, predictions of peak glucose improved for 8 out of the 10 anesthesiologists, while predictions of opioid requirements improved for 7 of the 10 anesthesiologists. Feedback questionnaire responses revealed that the anesthesiologist primarily used the ML estimates as reference to modify their clinical judgement. ML models can improve anesthesiologists' estimation of clinical parameters. ML predictions primarily served as reference information that modified an anesthesiologist's clinical estimate.

Lower, Variable Intrathecal Opioid Doses, and the Incidence of Prolonged Fetal Heart Rate Decelerations After Combined Spinal Epidural Analgesia for Labor: A Quality Improvement Analysis.

BACKGROUND: Combined spinal-epidurals with low-dose intrathecal opioids and local anesthetics are commonly used to initiate labor analgesia due to the fast onset of analgesia and good patient satisfaction. Intrathecal fentanyl has been associated with fetal bradycardia, and the rate may be higher at doses of 25 mcg and above. As such, our institution limits intrathecal fentanyl doses to less than 15 mcg for labor. Prompted by a few incidents of prolonged fetal bradycardia at even these low doses, we sought to audit the side effects associated with varying low doses of intrathecal fentanyl. METHODS: After IRB approval, a retrospective review was performed on 555 labor records from May-December, 2016. All the patients received combined spinal epidurals for labor analgesia. Intrathecal medication consisted of 1 mL of 0.25% bupivacaine, and varying fentanyl doses: 2.5, 5, 10, and 15 mcg. The incidences of prolonged fetal heart rate decelerations, emergent cesarean delivery, magnitude of pain reduction, pruritus requiring treatment, and hypotension were compared. RESULTS: Demographic variables were equivalent between the groups. There were no differences in the rates of prolonged fetal decelerations (in order of increasing fentanyl dose: 4.4%, 2.3%, 7.6%, 3.0%, p-value = 0.11), emergent cesarean delivery, magnitude of pain reduction, pruritus, or maternal hypotension. CONCLUSIONS: In conclusion, the rates of prolonged fetal heart rate decelerations after combined spinal epidural with intrathecal bupivacaine and fentanyl does not differ for fentanyl doses of 15 mcg and below.

Continuous Quadratus Lumborum Block for Postoperative Pain in Total Hip Arthroplasty: A Case Report.

A 69-year-old man with a history of chronic pain and opioid use presented for total hip arthroplasty. In the interests of ensuring early mobilization and pain control, we chose a continuous quadratus lumborum block technique, a novel ultrasound-guided block that has not yet been described for total hip arthroplasty, hypothesizing that it would be motor-sparing. While the perineural catheter was infused, the patient required no IV opioids. He was able to ambulate on the first postoperative day, reporting pain scores between 0 and 3/10. The quadratus lumborum block is a promising technique that, in our patient, was motor-sparing and provided excellent pain control.

Detection of pulse trains in the electrically stimulated cochlea: effects of cochlear health.

Perception of electrical stimuli varies widely across users of cochlear implants and across stimulation sites in individual users. It is commonly assumed that the ability of subjects to detect and discriminate electrical signals is dependent, in part, on conditions in the implanted cochlea, but evidence supporting that hypothesis is sparse. The objective of this study was to define specific relationships between the survival of tissues near the implanted electrodes and the functional responses to electrical stimulation of those electrodes. Psychophysical and neurophysiological procedures were used to assess stimulus detection as a function of pulse rate under the various degrees of cochlear pathology. Cochlear morphology, assessed post-mortem, ranged from near-normal numbers of hair cells, peripheral processes and spiral ganglion cells, to complete absence of hair cells and peripheral processes and small numbers of surviving spiral ganglion cells. The psychophysical and neurophysiological studies indicated that slopes and levels of the threshold versus pulse rate functions reflected multipulse integration throughout the 200 ms pulse train with an additional contribution of interactions between adjacent pulses at high pulse rates. The amount of multipulse integration was correlated with the health of the implanted cochlea with implications for perception of more complex prosthetic stimuli.

Development and characterization of a novel variable low dose-rate irradiator for in vivo mouse studies.

Radiation exposure of humans generally results in low doses delivered at low dose rate. Our limited knowledge of the biological effects of low dose radiation is mainly based on data from the atomic bomb Life Span Study (LSS) cohort. However, the total doses and dose rates in the LSS cohort are still higher than most environmental and occupational exposures in humans. Importantly, the dose rate is a critical determinant of health risks stemming from radiation exposure. Understanding the shape of the dose-rate response curve for different biological outcomes is thus crucial for projecting the biological hazard from radiation in different environmental and man-made conditions. A significant barrier to performing low dose-rate studies is the difficulty in creating radiation source configurations compatible with long-term cellular or animal experiments. In this study the design and characterization of a large area, I-based irradiator is described. The irradiator allows continuous long-term exposure of mice at variable dose rates and can be sited in standard animal care facilities. The dose rate is determined by the level of I activity added to a large NaOH-filled rectangular phantom. The desired dose rate is maintained at essentially constant levels by weekly additions of I to compensate for decay. Dosimetry results for long-term animal irradiation at targeted dose rates of 0.00021 and 0.0021 cGy min are presented.

18F-4V for PET-CT imaging of VCAM-1 expression in atherosclerosis.

OBJECTIVES: The aim of this study was to iteratively develop and validate an (18)F-labeled small vascular cell adhesion molecule (VCAM)-1 affinity ligand and demonstrate the feasibility of imaging VCAM-1 expression by positron emission tomography-computed tomography (PET-CT) in murine atherosclerotic arteries. BACKGROUND: Hybrid PET-CT imaging allows simultaneous assessment of atherosclerotic lesion morphology (CT) and may facilitate early risk assessment in individual patients. The early induction, confinement of expression to atherosclerotic lesions, and accessible position in proximity to the blood pool render the adhesion molecule VCAM-1 an attractive imaging biomarker for inflamed atheroma prone to complication. METHODS: A cyclic, a linear, and an oligomer affinity peptide, internalized into endothelial cells by VCAM-1-mediated binding, were initially derivatized with DOTA to determine their binding profiles and pharmacokinetics. The lead compound was then (18)F-labeled and tested in atherosclerotic apoE(-/-) mice receiving a high-cholesterol diet as well as wild type murine models of myocardial infarction and heart transplant rejection. RESULTS: The tetrameric peptide had the highest affinity and specificity for VCAM-1 (97% inhibition with soluble VCAM-1 in vitro). In vivo PET-CT imaging using (18)F-4V showed 0.31 +/- 0.02 SUV in murine atheroma (ex vivo %IDGT 5.9 +/- 1.5). (18)F-4V uptake colocalized with atherosclerotic plaques on Oil Red O staining and correlated to mRNA levels of VCAM-1 measured by quantitative reverse transcription polymerase chain reaction (R = 0.79, p = 0.03). Atherosclerotic mice receiving an atorvastatin-enriched diet had significantly lower lesional uptake (p < 0.05). Furthermore, (18)F-4V imaging in myocardial ischemia after coronary ligation and in transplanted cardiac allografts undergoing rejection showed high in vivo PET signal in inflamed myocardium and good correlation with ex vivo measurement of VCAM-1 mRNA by quantitative polymerase chain reaction. CONCLUSIONS: (18)F-4V allows noninvasive PET-CT imaging of VCAM-1 in inflammatory atherosclerosis, has the dynamic range to quantify treatment effects, and correlates with inflammatory gene expression.

Nanoparticle PET-CT imaging of macrophages in inflammatory atherosclerosis.

BACKGROUND: Macrophages participate centrally in atherosclerosis, and macrophage markers (eg, CD68, MAC-3) correlate well with lesion severity and therapeutic modulation. On the basis of the avidity of lesional macrophages for polysaccharide-containing supramolecular structures such as nanoparticles, we have developed a new positron emission tomography (PET) agent with optimized pharmacokinetics to allow in vivo imaging at tracer concentrations. METHODS AND RESULTS: A dextranated and DTPA-modified magnetofluorescent 20-nm nanoparticle was labeled with the PET tracer 64Cu (1 mCi/0.1 mg nanoparticles) to yield a PET, magnetic resonance, and optically detectable imaging agent. Peak PET activity 24 hours after intravenous injection into mice deficient in apolipoprotein E with experimental atherosclerosis mapped to areas of high plaque load identified by computed tomography such as the aortic root and arch and correlated with magnetic resonance and optical imaging. Accumulated dose in apolipoprotein E-deficient aortas determined by gamma counting was 260% and in carotids 392% of respective wild-type organs (P<0.05 both). Autoradiography of aortas demonstrated uptake of the agent into macrophage-rich atheromata identified by Oil Red O staining of lipid deposits. The novel nanoagent accumulated predominantly in macrophages as determined by fluorescence microscopy and flow cytometry of cells dissociated from aortas. CONCLUSIONS: This report establishes the capability of a novel trimodality nanoparticle to directly detect macrophages in atherosclerotic plaques. Advantages include improved sensitivity; direct correlation of PET signal with an established biomarker (CD68); ability to readily quantify the PET signal, perform whole-body vascular surveys, and spatially localize and follow the trireporter by microscopy; and clinical translatability of the agent given similarities to magnetic resonance imaging probes in clinical trials.