Comparison of Repeated Fluid-Air Exchange and Passive Drainage for Removing Residual Emulsified Silicone Oil Droplets

Purpose. To compare the efficacy of passive drainage (PD) and repeated fluid-air (FA) exchange for removing emulsified silicone oil (SO) droplets. Methods. Twenty rhegmatogenous retinal detachment (RRD) patients who underwent primary pars plana vitrectomy (PPV) with SO tamponade were randomly and evenly divided into two groups for PD and FA exchange. Once the bulk of SO was removed, the first 2 mL of the washout fluid was collected, and then, another 2 mL of the washout fluid was collected after PD or FA exchange. The size and number of SO droplets in the washout fluid were measured using a Coulter counter (Multisizer 3, Beckman Coulter, Indianapolis, IN, USA). The efficiencies of FA exchange and PD for removing emulsified SO were compared. Results. The number of SO droplets decreased significantly after FA exchange and PD. The decrease in the number of droplets was statistically significant for larger droplets (>4 µm) with PD and for all droplet sizes with FA exchange. The decrease in the number of SO droplets of <4 μm was significantly greater with FA exchange than with PD. However, at the end of the procedure, the overall number and size distribution of SO droplets were similar for both procedures. Conclusions. PD and FA exchange reduced the number of residual emulsified SO droplets after SO tamponade efficiently. FA exchange may have some advantages over PD in removing small droplets.

Theoretical and Experimental Gas Volume Quantification of Micro- and Nanobubble Ultrasound Contrast Agents

The amount of gas in ultrasound contrast agents is related to their acoustic activity. Because of this relationship, gas volume has been used as a key variable in normalizing the in vitro and in vivo acoustic behavior of lipid shell-stabilized bubbles with different sizes and shell components. Despite its importance, bubble gas volume has typically only been theoretically calculated based on bubble size and concentration that is typically measured using the Coulter counter for microbubbles and nanoparticle tracking analysis (NTA) for nanoscale bubbles. However, while these methods have been validated for the analysis of liquid or solid particles, their application in bubble analysis has not been rigorously studied. We have previously shown that resonant mass measurement (RMM) may be a better-suited technique for sub-micron bubble analysis, as it can measure both buoyant and non-buoyant particle size and concentration. Here, we provide validation of RMM bubble analysis by using headspace gas chromatography/mass spectrometry (GC/MS) to experimentally measure the gas volume of the bubble samples. This measurement was then used as ground truth to test the accuracy of theoretical gas volume predictions based on RMM, NTA (for nanobubbles), and Coulter counter (for microbubbles) measurements. The results show that the headspace GC/MS gas volume measurements agreed well with the theoretical predictions for the RMM of nanobubbles but not NTA. For nanobubbles, the theoretical gas volume using RMM was 10% lower than the experimental GC/MS measurements; meanwhile, using NTA resulted in an 82% lower predicted gas volume. For microbubbles, the experimental gas volume from the GC/MS measurements was 27% lower compared to RMM and 72% less compared to the Coulter counter results. This study demonstrates that the gas volume of nanobubbles and microbubbles can be reliably measured using headspace GC/MS to validate bubble size measurement techniques. We also conclude that the accuracy of theoretical predictions is highly dependent on proper size and concentration measurements.

Silicone Oil Emulsification after Vitrectomy for Rhegmatogenous Retinal Detachment

Purpose. To investigate the characteristics of silicone oil (SO) emulsification after vitrectomy for rhegmatogenous retinal detachment and their possible correlations with clinical factors. Methods. The first 2 mL of washing out fluid after SO removal was collected, and used for the measurement of the size and number of SO droplets using a Multisizer® 3 Coulter counter (Beckman Coulter, USA). The correlations between SO droplets and clinical factors were analyzed. Results. A total of 38 patients (23 males, 15 females) who underwent primary PPV with SO injection for RRD and whose retina stayed attached for ≥3 months after SO removal were included in the study. The average number of oil droplets was 1.96 × 106 ± 3.95 × 106/mL (range 0.17 × 106 to 21.71 × 106/ml), and 80.8% (range 64.23%–99.07%) of the droplets were 1-2 μm in diameter. The total number of emulsified SO droplets was not correlated with any clinical factor (all P>0.05). When the emulsified SO droplets were divided into groups by their diameter, multiple linear regression revealed that age was negatively correlated with the numbers of 5–7-μm-diameter and 7–12-μm-diameter droplets (both P<0.05). Patients using antiglaucoma medications had more 5–7-μm-diameter and 7–12-μm-diameter droplets than those not using (all P<0.05). Conclusion. Using a Multisizer® Coulter counter, we successfully determined the number and size of SO droplets after emulsification. We found that the number of 5–12-μm-diameter droplets was higher in younger-age patients and was higher in patients using antiglaucoma eyedrops.

Label-free counting of affinity-enriched circulating tumor cells (CTCs) using a thermoplastic micro-Coulter counter (μCC)

A micro-Coulter Counter (μCC) with simple and low cost fabrication process was developed and integrated with a circulating tumor cell (CTC) selection chip, providing label-free cell counting for CTC analysis.

Continuous Noninvasive Haemoglobin Monitoring in Vascular Surgery within the Goal-Directed Therapy Protocol

The optimisation of DO2, within the Goal-Direct Therapy Protocol (GDTP) in high-risk surgical patients, improves their outcome. Haemodynamic and haemoglobin monitoring become crucial to achieve optimal DO2. Our study compared Hb as measured by three methods: Coulter Counter (standard laboratory method) and CO-Oximetry (Masimo rainbow SET Radical 7 Pulse CO-Oximetry (SpHb) and Blood Gas Analysis) to establish the utility of the Hb continuous intraoperative monitoring, within the GDTP, in high-risk bleeding surgery. We studied 72 patients undergoing open abdominal aortic aneurysm repair. We compared the accuracy and the trending ability in measuring the haemoglobin concentration between the three methods (Coulter Counter, BGA and Masimo). We collected three simultaneous haemoglobin measurements: after induction of anaesthesia, pre- and post-aortic cross-clamping and at the end of the surgery. SpHb showed an excellent r-value for all samples (0.952, CI-95% (0.939, 0.961), p-value < 0.0001) compared to laboratory measurements. The results of the linear regression between SpHb and laboratory, for each time considered, demonstrated that SpHb showed excellent r and R2 value. All data were statistically significant, with a p-value <0.0001. A Bland-Altmann analysis for SpHb vs. laboratory showed a bias of −1.45 g/dL (CI-95% −1.51 and −1.39 g/dL, LOA from −2.42 to −0.48 g/dL) with a precision of 0.49 g/dL. Four-quadrant plot trend analyses showed a high concordance rate ≥90%. During elective high-risk surgery, Masimo Pulse CO-Oximetry is not enough sufficiently accurate to assess the current value of haemoglobin but may be useful for the trend value ensuring DO2 within intraoperative GDTP.

Processing code-multiplexed Coulter signals via deep convolutional neural networks

Deep learning-enhanced Coulter counter networks for electronic tracking of particles in microfluidic devices.