The superiority of midazolam-pethidine combination in three different anesthetic methods applied in conscious sedation during transesophageal echocardiography procedure

Background: During the transesophageal echocardiography (TEE) procedure, as in many other diagnostic semi-invasive applications, moderate sedation is preferred over deep sedation. Rarely, patients who cannot tolerate moderate sedation may require deep sedation when difficulties are encountered during TEE probe insertion. Although many different methods have been tried for the TEE procedure in clinical practice, the most appropriate sedation method is still controversial. Aims and Objectives: We aimed to evaluate the clinical effects of three different sedoanalgesia methods consisting of midazolam, propofol, and midazolam-pethidine combination protocols applied for conscious sedation in the patients undergoing a TEE procedure, and to evaluate the patient and doctor satisfaction during the procedure. Materials and Methods: One-hundred twenty five patients who underwent TEE for diagnostic purposes in our hospital were included consecutively in our prospective randomized trial. The patients were divided into three groups as those who were administered midazolam (group M), propofol (group Pr), and midazolam-pethidine (group MPe) during the TEE procedure. Results: In the MPe group, both patient and doctor satisfaction were significantly higher than the two groups. The rate of difficulty in probe placement was lower in the Pr and MPe groups compared to the M group (P<0.05). Conclusion: In this study, it has been observed that conscious sedation with the combination of midazolam-pethidine was significantly advantageous in terms of patient and physician satisfaction compared to the use of only midazolam and only propofol.

Measurement of Tissue Oximetry in Standing Unsedated and Sedated Horses

Near infrared spectroscopy (NIRS) noninvasively measures peripheral tissue oxygen saturation (StO2) and may be useful to detect early changes in StO2 in anaesthetized and critically ill horses. This study aimed to identify the muscle belly that provided the highest percentage of successful StO2 readings and the highest mean StO2 value. Fifty adult horses were enrolled in a prospective controlled study. StO2 was measured at six different muscles in each horse, for each intervention: hair overlying the muscle was clipped (post clipping: PC), clipped skin was cleaned with chlorhexidine (post-surgical prepping: PP) and medetomidine was administered intravenously (post medetomidine: PM). Mean StO2 values were calculated for each muscle, and a linear effects model was used to assess the effect of muscle group and intervention on StO2. The sartorius muscle gave the highest percentage of successful StO2 values (p < 0.001) and the highest mean (90% CI) StO2 values for the PC, PP and PM interventions. Surgical prepping of the skin increased the success for measurement of StO2 values. For all muscles, administration of medetomidine was associated with lower StO2 values (p < 0.001). In conclusion, of the muscles examined, the sartorius muscle may be the preferred muscle to measure StO2 in horses, and clipping and cleaning of the probe placement site is recommended.

Analytical Modeling of Sensitivity Parameters Influenced by Practically Feasible Arrangement of Bio-molecules in Dielectric Modulated FET Biosensor

In this paper, analytical modeling of a Dielectric Modulated Double Gate Field Effect Transistor (DM-DGFET) for biosensing application is presented with extensive data analysis. Firstly, the size of the nanogaps and arrangements of biomolecules in those gaps are optimized with respect to the sensitivity of the above sensor. The optimized DM-DGFET is next analyzed on the basis of its modeling and simulation. This paper addresses novel issues arising from arrangements of biomolecules, especially from practical point of view. Effect of probe placement due to steric hindrance and random nature of biomolecules, are also considered. The capacitances associated with the nanogaps occupied by biomolecules, following various arrangements, are modeled. Expressions of the threshold voltage, drain current and its sensitivity in terms of variations are also derived using the capacitance model. A comparative study of the proposed and the existing architectures is made. The influence of process variation on the sensitivity of the sensor is also studied. The results from the proposed analytical model are validated with the simulated data obtained from TCAD device simulator. In conclusion, the proposed DM-DGFET based biosensor architecture will emerge as an optimal model, very useful for the study on this field in future.

Accuracy of pedicle localization using a 3D ultrasound navigator on vertebral phantoms for posterior spinal surgery

Severe adolescent idiopathic scoliosis (AIS) requires surgery to halt curve progression. Accurate insertion of pedicle screws is important. This study reports a newly developed 3D ultrasound (3DUS) to localize pedicles intraoperatively and register a pre-op 3D vertebral model to the surface to be displayed for navigation. The objective was to determine speed of the custom 3DUS navigator and accuracy of pedicle probe placement. The developed 3DUS navigator integrated an ultrasound scanner with motion capture cameras. Two adolescent 3D printed spine models T2-T8 and T7-T11 were modified to include pedicle holes with known trajectory and be mounted on a high precision LEGO pegboard in a water bath for imaging. Calibration of the motion cameras and the 3DUS were conducted prior to the study. A total of 27 scans from T3 to T11 vertebrae with 3 individual scans were performed to validate the repeatability. Three accuracy tests that varied vertebral a) orientation, b) position and c) a combination of location and orientation were completed. Based on all experiments, the acquisition-to-display time was 18.9±3.1s. The repeatability of the trajectory error and positional error were 0.5±0.2° and 0.3±0.1mm, respectively. The a) center orientation, b) position and c) orientation/position on trajectory and positional error were for a) 1.4±0.9° and 0.5±0.4mm, b) 1.4±0.8° and 0.3±0.3mm and c) 2.0±0.8° and 0.5±0.5mm, respectively. These results demonstrated that a high precision real-time 3DUS navigator for screw placement in scoliosis surgery is feasible. The next step will study the effect of surrounding soft tissues on navigation accuracy.

Placement of finger oximeter on the ear: comparison with oxygen saturation values taken from the finger

Pulse oximetry is widely used to assess oxygen saturation (SpO2) in order to guide patient care and monitor the response to treatment. However, inappropriate oximeter probe placement has been shown to affect the measured oximetry values in healthy and normoxic outpatients. This study evaluated how treatment decisions might be impacted by SpO2 values obtained using a finger probe placed on the pinna of the ear in a cohort of 46 patients receiving non-invasive ventilation compared with values obtained from a probe on the finger and the results of arterial blood gas (ABG) (SaO2) analysis. Bland-Altman analysis was performed to evaluate agreement between the methods. Finger probe saturation was not statistically different from SaO2, with a mean difference of -0.66% (P>0.05). Saturation from the ear was significantly different (-4.29%; P<0.001). Subgroup analysis in hypoxic patients (SaO2<90%) showed a significant difference between ABG SaO2, and finger and ear SpO2. The study provides evidence that placement of a finger probe on the ear is unsafe clinical practice, potentially leading to patient mismanagement.

Changes in Muscle Hardness from Resting to Mid-Range Lengthened Positions Detected by Shear Wave Elastography (SWE) with a Novel Protocol of Ultrasound Probe Placement

Muscle hardness and its relationship with different muscle lengths/positions are important for understanding its underlying physiological status, and yet remained unclear. This study aimed to detect the local muscle hardness at different muscle lengths and identify the influence of muscle position on muscle hardness in healthy adults. A total of 26 healthy adults participated in this study. Shear wave elastography (SWE) was used to measure the muscle hardness of the Rectus Femoris (RF), Tibialis Anterior (TA) and Gastrocnemius Medialis (GM). Each muscle was tested at both resting (RST) and mid-range lengthened (MRL) positions. A novel ultrasound probe placing method was introduced, applied, and evaluated in this study. Moderate to excellent intra-/inter-rater reliability (Intraclass Correlation Coefficient, ICC ≥ 0.70) was found for muscle hardness measurements. The muscle hardness significantly increased from the RST to MRL position for all three muscles (p < 0.001). This study found that the muscle hardness increased at its mid-range lengthened position from the resting position. The mid-range lengthened muscle position of TA and GM could also be sensitive enough to reflect the age-related changes in local muscle hardness. This study also highlights the importance of placing the assessed extremities in an appropriate and consistent position when assessing muscle qualities by ultrasonics in clinical practice.

Individualized Brain Tissue Oxygen-Monitoring Probe Placement Helps to Guide Therapy and Optimizes Outcome in Neurocritical Care

Background/Objective In order to monitor tissue oxygenation in patients with acute neurological disorders, probes for measurement of brain tissue oxygen tension (ptO2) are often placed non-specifically in a right frontal lobe location. To improve the value of ptO2 monitoring, placement of the probe into a specific area of interest is desirable. We present a technique using CT-guidance to place the ptO2 probe in a particular area of interest based on the individual patient’s pathology. Methods In this retrospective cohort study, we analyzed imaging and clinical data from all patients who underwent CT-guided ptO2 probe placement at our institution between October 2017 and April 2019. Primary endpoint was successful placement of the probe in a particular area of interest rated by two independent reviewers. Secondary outcomes were complications from probe insertion, clinical consequences from ptO2 measurements, clinical outcome according to the modified Rankin Scale (mRS) as well as development of ischemia on follow-up imaging. A historical control group was selected from patients who underwent conventional ptO2 probe placement between January 2010 and October 2017. Results Eleven patients had 16 CT-guided probes inserted. In 15 (93.75%) probes, both raters agreed on the correct placement in the area of interest. Each probe triggered on average 0.48 diagnostic or therapeutic adjustments per day. Only one infarction within the vascular territory of a probe was found on follow-up imaging. Eight out of eleven patients (72.73%) reached a good outcome (mRS ≤ 3). In comparison, conventionally placed probes triggered less diagnostic and therapeutic adjustment per day (p = 0.007). Outcome was worse in the control group (p = 0.024). Conclusion CT-guided probe insertion is a reliable and easy technique to place a ptO2 probe in a particular area of interest in patients with potentially reduced cerebral oxygen supply. By adjusting treatment aggressively according to this individualized monitoring data, clinical outcome may improve.

Colour-Doppler echocardiography flow field velocity reconstruction using a streamfunction–vorticity formulation

We introduce a new method ( Do ppler Ve locity R econstruction or DoVeR), for reconstructing two-component velocity fields from colour Doppler scans. DoVeR employs the streamfunction–vorticity equation, which satisfies mass conservation while accurately approximating the flow rate of rotation. We validated DoVeR using artificial colour Doppler images generated from computational fluid dynamics models of left ventricle (LV) flow. We compare DoVeR against the conventional intraventricular vector flow mapping (iVFM 1D ) and reformulated iVFM (iVFM 2D ). LV model error analysis showed that DoVeR is more robust to noise and probe placement, with noise RMS errors ( nRMSE ) between 3.81% and 6.67%, while the iVFM methods delivered 4.16–24.17% for iVFM 1D and 4.06–400.21% for iVFM 2D . We test the DoVeR and iVFM methods using in vivo mouse LV ultrasound scans. DoVeR yielded more haemodynamically accurate reconstructions, suggesting that it can provide a more reliable approach for robust quantification of cardiac flow.