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1.
ASAIO J ; 2024 Apr 18.
Article in English | MEDLINE | ID: mdl-38635489

ABSTRACT

The study aimed to investigate the effect of red blood cell (RBC) morphology on oxygenator perfusion, focusing on stages of echinocytosis and their correlation with blood viscosity. A test circuit with an oxygenator and human RBC mixtures was used to induce changes in RBC shape by increasing sodium salicylate concentrations (0, 10, 20, 30, 60, and 120 mmol/L), while hematocrit, blood temperature, and anticoagulation were maintained. Blood viscosity was measured using a continuous blood viscosity monitoring system based on pressure-flow characteristics. Under a scanning electron microscope, the percentages of discocytes, echinocytes I-III, spheroechinocytes, and spherocytes were determined from approximately 400 cells per RBC sample. Early echinocytes, mainly discocytes and echinocytes I and II in the range of 0-30 mmol/L were predominant, resulting in a gradual increase in blood viscosity from 1.78 ± 0.12 to 1.94 ± 0.12 mPa s. At 60 mmol/L spherocytes emerged, and at 120 mmol/L, spheroidal RBCs constituted 50% of the population, and blood viscosity sharply rose to 2.50 ± 0.15 mPa s, indicating a 40% overall increase. In conclusion, the presence of spherocytes significantly increases blood viscosity, which may affect oxygenator perfusion.

2.
IEEE J Transl Eng Health Med ; 11: 435-440, 2023.
Article in English | MEDLINE | ID: mdl-37534100

ABSTRACT

Cardiopulmonary bypass (CPB) is an indispensable technique in cardiac surgery, providing the ability to temporarily replace cardiopulmonary function and create a bloodless surgical field. Traditionally, the operation of CPB systems has depended on the expertise and experience of skilled perfusionists. In particular, simultaneously controlling the arterial and venous occluders is difficult because the blood flow rate and reservoir level both change, and failure may put the patient's life at risk. This study proposes an automatic control system with a two-degree-of-freedom model matching controller nested in an I-PD feedback controller to simultaneously regulate the blood flow rate and reservoir level. CPB operations were performed using glycerin and bovine blood as perfusate to simulate flow-up and flow-down phases. The results confirmed that the arterial blood flow rate followed the manually adjusted target venous blood flow rate, with an error of less than 5.32%, and the reservoir level was maintained, with an error of less than 3.44% from the target reservoir level. Then, we assessed the robustness of the control system against disturbances caused by venting/suction of blood. The resulting flow rate error was 5.95%, and the reservoir level error 2.02%. The accuracy of the proposed system is clinically satisfactory and within the allowable error range of 10% or less, meeting the standards set for perfusionists. Moreover, because of the system's simple configuration, consisting of a camera and notebook PC, the system can easily be integrated with general CPB equipment. This practical design enables seamless adoption in clinical settings. With these advancements, the proposed system represents a significant step towards the automation of CPB.


Subject(s)
Cardiac Surgical Procedures , Cardiopulmonary Bypass , Humans , Animals , Cattle , Catheters, Indwelling , Heart-Lung Machine
3.
Clin Plast Surg ; 50(1): 91-100, 2023 Jan.
Article in English | MEDLINE | ID: mdl-36396265

ABSTRACT

A primary concern in facial aesthetics is the rejuvenation of periorbital areas through soft tissue recontouring, skin texture improvement, and harmoniousness with souring anatomic tissues. Currently, the ease of harvesting, abundance in volume, and lack of immune rejection make autologous fat transplantation a disruptive strategy in aesthetic medicine. The evolution and improvements made by myriad surgeons have contributed to the popularity of periorbital rejuvenation and have highlighted its indispensability in Asian patients. Lin and colleagues have advocated the technique of microautologous fat transplantation since 2007 for facial recontouring and rejuvenation. This article illustrates more in-depth technical details and innovative concepts for the improvement of the periorbita.


Subject(s)
Face , Rejuvenation , Humans , Face/surgery , Esthetics , Transplantation, Autologous/methods , Asian People
4.
Asian Cardiovasc Thorac Ann ; : 2184923211072595, 2022 Jan 18.
Article in English | MEDLINE | ID: mdl-35040360

ABSTRACT

BACKGROUND: The purpose of this study was to clarify the efficacy of the combination of low-voltage coagulation plus staple line coverage with a polyglycolic acid sheet after bullectomy for primary spontaneous pneumothorax to prevent a postoperative recurrence. METHODS: A total of 143 patients who underwent bullectomy for primary spontaneous pneumothorax between January 2014 and December 2019 were enrolled in this study. We classified the patients into two groups based on additional procedures after bullectomy, namely, low-voltage coagulation for the margin of the staple line plus coverage with a polyglycolic acid sheet (Group A) and staple line coverage with a polyglycolic acid sheet alone (Group B). We evaluated perioperative factors and recurrence-free survival after surgery in the two groups. RESULTS: Nine patients in Group B developed postoperative recurrences. In contrast, there was no postoperative recurrence in Group A. According to the Kaplan-Meier curves, the 2-year recurrence-free survival rates of the patients were 100% and 90.3%, in Group A and Group B, respectively. The log-rank test showed a significant difference between the two groups (p = 0.031). CONCLUSION: Low-voltage coagulation for the margin of a staple line plus coverage with a polyglycolic acid sheet is a useful option as an additional technique after bullectomy for primary spontaneous pneumothorax to prevent a postoperative recurrence.

5.
Annu Int Conf IEEE Eng Med Biol Soc ; 2021: 5011-5014, 2021 11.
Article in English | MEDLINE | ID: mdl-34892332

ABSTRACT

The operation of the cardiopulmonary bypass (CPB) system requires skilled techniques and experience. Intraoperatively, the perfusionist needs to intermittently manipulate both of the occluders on the venous- and arterial-line sides to achieve the desired blood flow rates. To facilitate the occluder operation, we propose an automatic control system for the arterial-line side blood flow rate based on a dynamic model that addresses the relationship between the occluder operation and blood flow rate in the CPB system. The simulation results demonstrated that the proposed system was able to control the blood flow rate even when the estimation error of the model parameters was presented. Then, we implemented this control system in the CPB system and conducted an experiment to automatically control the arterial-line side blood flow rate. We confirmed that the blood flow rate on the arterial-line side could follow the manually operated venous-line side blood flow rate.Clinical Relevance--- The automatic blood flow rate control system for a cardiopulmonary bypass system, proposed in this paper, contributes to reducing the burden of occluder operation on a perfusionist.


Subject(s)
Cardiopulmonary Bypass
6.
J Surg Case Rep ; 2021(9): rjab385, 2021 Sep.
Article in English | MEDLINE | ID: mdl-34522322

ABSTRACT

Lipomas are benign tumors that originate from mesenchymal tissue, such as subcutaneous tissue. Intrathoracic lipomas are rare, and they can occur in the chest wall, mediastinum and bronchi. In the present case, the patient had an intrathoracic lipoma that was located in the horizontal fissure of the right lung. Retrospective review of chest radiographs taken at a previous health checkup confirmed that the tumor was growing. The patient had no symptoms, and computed tomography and magnetic resonance imaging suggested that the tumor was a hamartoma. The tumor was resected by video-assisted thoracic surgery, and was diagnosed by pathological analysis as an intrathoracic lipoma consisting of no atypical fats.

7.
Aesthet Surg J ; 41(6): NP260-NP266, 2021 05 18.
Article in English | MEDLINE | ID: mdl-33400770

ABSTRACT

BACKGROUND: Severe blepharoptosis with poor levator function (LF) has traditionally been managed with exogenous frontalis suspension but complications such as lagophthalmos, infection, and rejection are often reported. OBJECTIVES: The aim of this study was to design a function-preserving frontalis orbicularis oculi muscle (FOOM) flap to correct severe blepharoptosis with poor LF. The long-term surgical outcome of the technique was assessed. METHODS: This retrospective study included only adult patients with severe blepharoptosis and poor LF, all of whom had their surgery performed by the senior surgeon over a 6-year period. Clinical assessment of LF, palpebral fissure height (PFH), marginal reflex distance 1 (MRD1), duration of follow-up, and postoperative complications were recorded. RESULTS: A total of 34 patients and 59 eyelids were recorded during a mean follow-up period of 17.7 months. Postoperative evaluation yielded mean [standard deviation] improvements of PFH gain of 5.62 [1.61] mm (P < 0.001), and MRD1 and PFH increases of 4.03 [0.82] mm (P < 0.001) and 8.94 [0.81] mm (P < 0.001), respectively. All patients demonstrated normalization of orbicularis function: no lagophthalmos was observed at the 8-month postoperative follow-up. Recurrence of ptosis was recorded in 4 eyelids (6.78%). Revisions were performed in 2 eyelids (3.39%). No infection or granuloma was noted. CONCLUSIONS: The function-preserving FOOM flap is a useful vector for frontalis suspension. Not only does it effectively address lagophthalmos as well as other complications, but it provides aesthetically pleasing outcomes in patients with severe blepharoptosis and poor LF.


Subject(s)
Blepharoplasty , Blepharoptosis , Adult , Blepharoplasty/adverse effects , Blepharoptosis/surgery , Eyelids/surgery , Humans , Oculomotor Muscles/surgery , Retrospective Studies , Treatment Outcome
8.
Clin Plast Surg ; 47(1): 91-98, 2020 Jan.
Article in English | MEDLINE | ID: mdl-31739902

ABSTRACT

The concept of microautologous fat transplantation (MAFT), proposed by Lin and colleagues in 2007, emphasized that the volume of each delivered parcel should be less than 0.01 mL to avoid potential fat grafting morbidities. The MAFT-GUN facilitates control of the parcel volume and therefore substantially avoids central necrosis and associated complications. In this article, the authors present a simple, reliable, and consistent procedure based on MAFT for profiloplasty. Favorable outcomes with sustainable long-term effectiveness were obtained, further confirming that the MAFT technique is an alternative for facial contouring in the nose and chin.


Subject(s)
Adipose Tissue/transplantation , Body Contouring , Chin/surgery , Nose/surgery , Humans , Transplantation, Autologous
9.
Medicine (Baltimore) ; 98(23): e15853, 2019 Jun.
Article in English | MEDLINE | ID: mdl-31169689

ABSTRACT

INTRODUCTION: Meningioma is mostly a benign tumor, but sometimes it is malignant, and there have been reports of distant metastases. PATIENT CONCERNS: The patient, a woman in her 40s, was under follow-up after resection of an ectopic malignant meningioma originating in the left axilla. She was referred to our department because of a nodule shadow in the right lung on chest computed tomography (CT) 3 years and 5 months postoperatively. DIAGNOSIS: Chest CT showed a 1.0 cm nodule shadow in the right S4, which was positive on positron emission tomography-CT; no abnormality was found in any other organ. Therefore, it was considered to be a metastatic lung tumor. INTERVENTIONS: Right middle lobe partial resection was performed using thoracoscopic surgery, and a diagnosis of pulmonary metastasis of ectopic malignant meningioma was made by histopathology and immunohistochemistry. OUTCOMES: In this case, complete resection was possible. CONCLUSION: Meningioma occurs mainly in the cranium, and occurrence in the soft tissue of the extremities is extremely rare. To our knowledge, ours is the first report of a histologically malignant ectopic meningioma with metastasis to the thoracic cavity.


Subject(s)
Lung Neoplasms/secondary , Meningeal Neoplasms/pathology , Meningioma/pathology , Adult , Female , Humans , Lung Neoplasms/surgery , Meningeal Neoplasms/surgery , Meningioma/surgery
10.
Oncol Lett ; 17(6): 5125-5131, 2019 Jun.
Article in English | MEDLINE | ID: mdl-31186726

ABSTRACT

Epidermal growth factor receptor (EGFR) is the most important driver gene of non-small cell lung cancer (NSCLC) as EGFR mutations determine the efficacy of EGFR tyrosine kinase inhibitor (EGFR-TKI) therapy. In the present study, the comprehensive ability of widely used polymerase chain reaction (PCR) methods to detect EGFR mutations was determined. Among the 35 EGFR mutations detected via the direct sequencing of 73 patients with NSCLC, 11 types were identified in exons 18, 19 and 21. Among the 11 mutation types, all exon 18 and 21 mutations were identified by 2 widely used PCR methods, namely, Scorpion-Amplification Refractory Mutation System and cobas v2. However, among the 9 different exon 19 deletions, 3 types were not identified by the 2 methods. In addition, 25 samples with EGFR mutations were analyzed by the 2 methods, including a sample from a patient with an unidentified exon 19 deletion, the T751_I759 deletion and insertion S; this patient had long-term disease control as a result of EGFR-TKI therapy. The 2 methods could not detect this unidentified deletion, whereas sizing capillary electrophoresis for the comprehensive detection of exon 19 deletions detected this deletion. It is generally thought that patients with exon 19 mutations have higher response rates to EGFR-TKI therapy than patients with exon 21 mutations. The present study confirmed the EGFR mutation status by comparing the mutations with the Catalog Of Somatic Mutations In Cancer, which is the world's largest and most comprehensive resource for analyzing the effects of somatic mutations in human cancers. The predicted frequency of EGFR mutations identified by the 2 methods was 85%. The frequency of mutations detectable by the 2 methods was less for exon 19 than exon 21. Therefore, the results of the present study suggest that decreasing false-negative detection of exon 19 deletions is crucial for the clinical testing of EGFR mutations.

11.
Aesthet Surg J ; 39(11): 1163-1177, 2019 10 15.
Article in English | MEDLINE | ID: mdl-30668643

ABSTRACT

BACKGROUND: Lower blepharoplasty has been used for rejuvenating lower eyelids, and diverse modifications have been used to treat conjunct deformities at the tear trough/lid-cheek junction. Strategies for recontouring prominent tear trough/lid-cheek junctions, including orbital fat manipulation, have been reported with good results in the literature. Micro-autologous fat transplantation (MAFT) is a previously unevaluated, potentially advantageous approach to blending the prominent tear trough/lid-cheek junction. OBJECTIVES: We determined the long-term results after 3-step transcutaneous lower blepharoplasty with MAFT for patients with aging eyelids and prominent tear trough/lid-cheek junctions. METHODS: We evaluated 205 patients with aging lower eyelids who underwent transcutaneous lower blepharoplasty with MAFT between October 2010 and September 2016. The 3-step procedure involved a subciliary elliptical skin excision, resection of 3 orbital fat compartments, and MAFT for the tear trough/lid-cheek junction employing a MAFT-GUN under intravenous anesthesia. RESULTS: The mean patient age was 52 years (range, 34-78 years). The mean operating time was 61 minutes. The mean fat volumes delivered to the tear trough/lid-cheek junctions were 2.80 mL and 2.76 mL for the left and right sides, respectively. The average weights of the 3 resected orbital fat compartments were 0.58 g for the left side and 0.56 g for the right side. Patients showed significant improvement and maintenance at an average follow-up of 60.2 months (range, 18-90 months). CONCLUSIONS: Three-step transcutaneous lower blepharoplasty with MAFT is an effective, reliable, and promising method with high patient satisfaction and minimal risk of complications. Long-term results demonstrated its utility for aging lower eyelid treatment.


Subject(s)
Adipose Tissue/transplantation , Blepharoplasty/methods , Microinjections/methods , Patient Satisfaction , Skin Aging , Adult , Aged , Blepharoplasty/instrumentation , Eyelids/surgery , Feasibility Studies , Female , Follow-Up Studies , Humans , Male , Microinjections/instrumentation , Middle Aged , Operative Time , Rejuvenation , Transplantation, Autologous/methods , Treatment Outcome
13.
Perfusion ; 33(7): 512-519, 2018 10.
Article in English | MEDLINE | ID: mdl-29635960

ABSTRACT

INTRODUCTION: Body temperature maintained during open distal anastomosis in patients who undergo aortic surgery has been showing an upward trend; however, a higher temperature may increase visceral organ and spinal cord injury. Distal perfusion may reduce abdominal organ injury, especially acute kidney injury (AKI). METHODS: From 2009 to 2016, 56 patients who underwent ascending aortic and/or aortic arch surgery were enrolled. Open distal anastomosis was performed using one of three protection strategies: 1) systemic temperature of 25°C followed by selective cerebral perfusion (SCP) with lower body circulatory arrest (Group CA25, n=27); 2) systemic temperature of 28°C followed by SCP with lower body circulatory arrest (Group CA28, n=4); and 3) systemic temperature of 28°C followed by SCP with distal aortic perfusion (Group DP, n=25). RESULTS: During the postoperative course, levels of blood urea nitrogen, creatinine, liver enzymes, lactate dehydrogenase and lactate in Groups CA28 and CA25 were significantly higher than those in Group DP. AKI defined by the AKI Network occurred in 28 cases (50%) and 3 cases required permanent hemodialysis. AKI was significantly higher in Groups CA25 and CA28 than in Group DP (p=0.026). Mid-term follow-up showed that patients who developed postoperative AKI were more likely to suffer from cardiovascular events. CONCLUSIONS: Distal perfusion during open distal anastomosis reduced kidney and liver injury after thoracic aortic surgery despite an increased body temperature of up to 28°C. This strategy may be useful to prevent AKI, liver dysfunction, the need for hemodialysis and multiple organ failure and could improve mid-term results.


Subject(s)
Abdomen/surgery , Acute Kidney Injury/etiology , Aortic Aneurysm/surgery , Adult , Aged , Aged, 80 and over , Female , Humans , Male , Middle Aged , Perfusion , Risk Factors , Young Adult
14.
Aesthet Surg J ; 38(9): 925-937, 2018 Aug 16.
Article in English | MEDLINE | ID: mdl-29566216

ABSTRACT

BACKGROUND: A gummy smile is treated using many techniques, including botulinum toxin injection and various surgical interventions. Micro-autologous fat transplantation (MAFT) is a potentially advantageous alternative approach that has not been previously evaluated. OBJECTIVES: This study sought to determine the long-term results of MAFT in patients with a gummy smile. METHODS: Seven patients with gummy smiles were evaluated for MAFT treatment between October 2015 and April 2017. Centrifuged purified fat was micro-transplanted into the nasolabial groove, ergotrid, and upper lip areas using the MAFT-GUN while the patients were under total intravenous anesthesia. RESULTS: The mean age of the 7 patients was 31 years (range, 23-40 years). The mean operating time for MAFT was 52 minutes (range, 40-72 minutes), and the mean volume of fat delivered to the nasolabial groove, ergotrid, and upper lip was 16.1 mL. The mean decreases of gingival display in the right canine incisor, left canine incisor, right canine, and left canine teeth were 4.9, 4.6, 3.8, and 4.4 mm, respectively. The smiles of the 7 patients showed significant improvement at an average follow-up time of 12.9 months. CONCLUSIONS: Gummy smile treatment using MAFT is an effective, reliable, and relatively simple method, with high patient satisfaction and minimal risk of complications.


Subject(s)
Abdominal Fat/transplantation , Cosmetic Techniques , Smiling , Adult , Female , Follow-Up Studies , Humans , Injections/methods , Lip/surgery , Male , Nasolabial Fold/surgery , Patient Satisfaction , Reproducibility of Results , Transplantation, Autologous/methods , Treatment Outcome , Young Adult
16.
Peptides ; 96: 31-37, 2017 Oct.
Article in English | MEDLINE | ID: mdl-28887046

ABSTRACT

Elegantin and angustatin, which were isolated from the snake venoms of Protobothrops elegans and Dendroaspis angusticeps, markedly inhibit binding between platelet integrins and fibrinogen via the Arg-Gly-Asp (RGD) sequence. Angustatin, which is a three-finger toxin containing the RGD sequence, inhibits platelet aggregation almost ten times more strongly than disintegrin isolated from the venoms of Viperidae and Crotalidae. The RGD sequences of both polypeptides are located at the top of hairpin loops, and the composition of the RGD loop is very important for binding to integrin. We investigated the effects of synthetic RGD loop peptides from angustatin and elegantin on ADP- or collagen-induced platelet aggregation and αIIbß3-fibrinogen binding. Synthetic angustatin (PRGDMP)-type peptides inhibited platelet aggregation more strongly than elegantin (ARGDDX)-type peptides. In particular, the cyclic angustatin peptide (CPRGDMPC) inhibited ADP- and collagen-induced platelet aggregation at least 10-50 times more strongly than the other peptides. The cyclic angustatin peptide (CPRGDMPC) was also the strongest inhibitor of binding between αIIbß3 and fibrinogen, the IC50 of this peptide was approximately 2.58µM. Regarding the inhibition of binding between αIIbß3 and fibrinogen, CPRGDMPC demonstrated a stronger inhibitory and more stable effect in the presence of Mg2+ than in the presence of Ca2+.


Subject(s)
Fibrinogen/metabolism , Integrin alpha2/metabolism , Integrin beta3/metabolism , Oligopeptides/chemistry , Peptides/chemistry , Humans , Peptides/chemical synthesis , Peptides/pharmacology , Protein Binding/drug effects
17.
Molecules ; 22(8)2017 Aug 04.
Article in English | MEDLINE | ID: mdl-28777331

ABSTRACT

Snake venom metalloproteinases (SVMP) are widely distributed among the venoms of Crotalinae and Viperidae, and are organized into three classes (P-I, P-II and P-III) according to their size and domain structure. P-I SVMP are the smallest SVMP, as they only have a metalloproteinase (M) domain. P-II SVMP contain a disintegrin-like (D) domain, which is connected by a short spacer region to the carboxyl terminus of the M domain. P-III SVMP contain a cysteine-rich (C) domain, which is attached to the carboxyl terminus of the D domain. Some SVMP exhibit hemorrhagic activity, whereas others do not. In addition, SVMP display fibrinolytic/fibrinogenolytic (FL) activity, and the physiological functions of SVMP are controlled by their structures. Furthermore, these proteinases also demonstrate fibrinogenolytic and proteolytic activity against synthetic substrates for matrix metalloproteinases and ADAM (a disintegrin and metalloproteinase). This article describes the structures and FL, hemorrhagic, and platelet aggregation-inhibiting activity of SVMP derived from Protobothrops snake venom that was collected in Japan.


Subject(s)
Crotalid Venoms/chemistry , Crotalinae , Metalloproteases/chemistry , Reptilian Proteins/chemistry , Animals , Japan , Protein Domains , Structure-Activity Relationship
18.
J Craniofac Surg ; 28(3): 629-634, 2017 May.
Article in English | MEDLINE | ID: mdl-28468137

ABSTRACT

OBJECTIVE: Sunken temporal fossa appears oftentimes in Asians and resembles bad fortune that people wish to change. Numerous techniques and materials have been applied clinically for augmenting the sunken temporal fossa with variable results. The microautologous fat transplantation (MAFT) technique proposed by Lin et al in 2006 has demonstrated favorable results in facial rejuvenation. In the present study, the authors applied the MAFT technique with an innovative instrument in sunken temporal fossa and reported its results. METHODS: Microautologous fat transplantation was performed on 208 patients during the 4-year period starting in January 2010. Fat was harvested by liposuction, processed and refined by centrifugation at 1200 g for 3 minutes. Then purified fat was microtransplanted to the temporal fossa with the assistance of an instrument, MAFT-Gun. The patients were followed up regularly and photographs were taken for comparison. RESULTS: On average, the MAFT procedure took 48 minutes to complete. The average delivered fat was 6.8 ±â€Š0.2 mL/6.5 ±â€Š0.3 mL for the right/left side. The average follow-up period was 18 months. No complication including skin necrosis, vascular compromise, nodulation, fibrosis, and asymmetry was noted. The patient-rated satisfaction 5-point Likert scale demonstrated that 81.3% of all patients had favorable results (38.5% very satisfied and 42.8% satisfied). CONCLUSIONS: The concept and technique of MAFT along with the micro- and precise controlling instrument enabled surgeons to perform fat grafting accurately and consistently. In comparison with other strategies for volume restoration, the MAFT procedure demonstrated the patients' high satisfaction with the long-term results. Therefore, the potential of MAFT as an alternative strategy in sunken temporal fossa in Asians was emphasized.


Subject(s)
Cosmetic Techniques , Subcutaneous Fat/transplantation , Adult , Face , Female , Follow-Up Studies , Humans , Lipectomy , Male , Middle Aged , Patient Satisfaction/statistics & numerical data , Retrospective Studies , Transplantation, Autologous
19.
Artif Organs ; 41(3): 262-266, 2017 Mar.
Article in English | MEDLINE | ID: mdl-27782314

ABSTRACT

During cardiopulmonary bypass (CPB), blood viscosity conspicuously increases and decreases due to changes in hematocrit and blood temperature. Nevertheless, blood viscosity is typically not evaluated, because there is no technology that can provide simple, continuous, noncontact monitoring. We modeled the pressure-flow characteristics of an oxygenator in a previous study, and in that study we quantified the influence of viscosity on oxygenator function. The pressure-flow monitoring information in the oxygenator is derived from our model and enables the estimation of viscosity. The viscosity estimation method was proposed and investigated in an in vitro experiment. Three samples of whole bovine blood with different hematocrit levels (21.8, 31.0, and 39.8%) were prepared and perfused into the oxygenator. As the temperature changed from 37°C to 27°C, the mean inlet pressure (Pin ) and outlet pressure (Pout ) of the oxygenator and the flow (Q) and viscosity of the blood were measured. The estimated viscosity was calculated from the pressure gradient (ΔP = Pin - Pout ) and Q and was compared to the measured blood viscosity. A strong correlation was found between the two methods for all samples. Bland-Altman analysis revealed a mean bias of -0.0263 mPa.s, a standard deviation of 0.071 mPa.s, limits of agreement of -0.114-0.166 mPa.s, and a percent error of 5%. Therefore, this method is considered compatible with the torsional oscillation viscometer that has plus or minus 5% measurement accuracy. Our study offers the possibility of continuously estimating blood viscosity during CPB.


Subject(s)
Blood Pressure , Blood Viscosity , Cardiopulmonary Bypass/instrumentation , Models, Cardiovascular , Oxygenators , Animals , Blood Flow Velocity , Cattle , Hematocrit , Predictive Value of Tests , Reproducibility of Results , Temperature , Time Factors
20.
IEEE Trans Biomed Eng ; 64(7): 1503-1512, 2017 07.
Article in English | MEDLINE | ID: mdl-27662668

ABSTRACT

This paper proposes an algorithm that estimates blood viscosity during cardiopulmonary bypass (CPB) and validates its application in clinical cases. The proposed algorithm involves adjustable parameters based on the oxygenator and fluid types and estimates blood viscosity based on pressure-flow characteristics of the fluid perfusing through the oxygenator. This novel nonlinear model requires four parameters that were derived by in vitro experiments. The results estimated by the proposed method were then compared with a conventional linear model to demonstrate the former's optimal curve fitting. The viscosity (ηe) estimated using the proposed algorithm and the viscosity (η) measured using a viscometer were compared for 20 patients who underwent mildly hypothermic CPB. The developed system was applied to ten patients, and ηe was recorded for comparisons with hematocrit and blood temperature. The residual sum of squares between the two curve fittings confirmed the significant difference, with p < 0.001. ηe and η showed a very strong correlation with R2 = 0.9537 and p < 0.001. Regarding the mean coefficient of determination for all cases, the hematocrit and temperature showed weak correlations at 0.33 ± 0.14 and 0.22 ± 0.21, respectively. For CPB measurements of all cases, ηe was more than 98% distributed in the range from 1 to 3 mPa⋅s. This new system for estimating viscosity may be useful for detecting various viscosity-related effects that may occur during CPB.


Subject(s)
Algorithms , Blood Viscosity , Cardiopulmonary Bypass/instrumentation , Cardiopulmonary Bypass/methods , Models, Cardiovascular , Monitoring, Intraoperative/instrumentation , Rheology/instrumentation , Computer Simulation , Equipment Design , Equipment Failure Analysis , Hemorheology , Humans , Reproducibility of Results , Sensitivity and Specificity
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