Clinical application of clot waveform analysis / 中华检验医学杂志

Bleeding and thrombotic diseases are closely related to various clinical departments. Laboratory-related tests play an important role in disease diagnosis and differential diagnosis, risk assessment, cause finding, and efficacy monitoring. Clot waveform analysis (CWA), as an automated coagulation detection technology, can provide more valuable information about the entire coagulation process of a plasma sample. A large number of studies have showed that CWA has certain value in the evaluation of coagulation status of COVID-19 patients, the judgment of clinical phenotype of hemophilia A (HA) patients, and the monitoring of direct oral anticoagulant drugs (DOAC). In-depth interpretation and application of CWA in different clinical settings can provide more laboratory information for diagnosis and treatment of bleeding and thrombotic diseases.

Measurement of FVIII:C Level by Clot Waveform Analysis / 임상소아혈액종양

BACKGROUND: By using ACL 9000 coagulation analyzer (Instrumentation Laboratory Co., Lexington, Massachusetts, USA), we tried to investigate the possibility that activated partial thromboplastin time (aPTT) clot waveform analysis (CWA) may provide additional information on patients with hemophilia A. METHODS: Plasma samples were obtained from 35 patients with hemophilia A. The factor VIII levels of those patients were measured by a conventional one-stage factor VIII:C clotting assay and a factor VIII antigen assay. The data were applied to a Microsoft excel program calculating the index of the second derivative, and the time at point b (Min2), the point in time that clotting is initiated was also calculated. RESULTS: The corresponding aPTT clotting times were prolonged in all 9 patients with severe hemophilia A. The CWA could further discriminate between different levels of FVIII:C in the patients (n=20), with a FVIII:C level <4 IU/dL by conventional assay. The correlation between FVIII:C and the recalculated aPTT using Min2 was very high in patients with FVIII:C < or =4 IU/dL (r=0.952). Among the 9 patients who showed a lot of discrepancy from the FVIII:C level, there was 8 patients with mild hemophilia and 1 patient with moderate hemophilia (FVIII:C level 4.5%). CONCLUSION: Our study suggested that CWA and Min2 values might have greater discriminatory power in assessing low clotting factor activity. Further study is needed, including more patients with hemophilia A using CWA, correlation according to the severity group, a lower limit of detection for VIII:C, and a multiple one-stage assay.

Similarity measurement of blood pressure waveforms for pulsatile flow simulation system / 医用生物力学

Objective To study a quantitative indicator for measuring the similarity between blood pressure waveforms and its application in the analysis on the simulated blood pressure waveform for pulsatile flow simulation system.Methods Based on the past similarity measurement algorithm and the known feature of blood pressure waveforms, the weighted average algorithm was presented in this paper, which possessed advantages of both global matching and partial matching by integrating the correlation coefficient with the characteristic parameter algorithm, and calculating similarity degrees through overall and partial waveform.Results The weighted average algorithm was proved to be more suitable for the analysis on the blood pressure waveform similarity compared with the angle cosine method, average absolute deviation method, and numeric similarity coefficient method.Conclusions The weighted average algorithm showed excellent ability in calculating the similarity degree between different waveforms, or in comparing the performance with different pulsatile flow simulation systems, and it could be applied to other physiological waveforms with further improvement.

Measurement of FVIII:C Level by Clot Waveform Analysis / 임상소아혈액종양

BACKGROUND: By using ACL 9000 coagulation analyzer (Instrumentation Laboratory Co., Lexington, Massachusetts, USA), we tried to investigate the possibility that activated partial thromboplastin time (aPTT) clot waveform analysis (CWA) may provide additional information on patients with hemophilia A.METHODS: Plasma samples were obtained from 35 patients with hemophilia A. The factor VIII levels of those patients were measured by a conventional one-stage factor VIII:C clotting assay and a factor VIII antigen assay. The data were applied to a Microsoft excel program calculating the index of the second derivative, and the time at point b (Min2), the point in time that clotting is initiated was also calculated.RESULTS: The corresponding aPTT clotting times were prolonged in all 9 patients with severe hemophilia A. The CWA could further discriminate between different levels of FVIII:C in the patients (n=20), with a FVIII:C level <4 IU/dL by conventional assay. The correlation between FVIII:C and the recalculated aPTT using Min2 was very high in patients with FVIII:C < or =4 IU/dL (r=0.952). Among the 9 patients who showed a lot of discrepancy from the FVIII:C level, there was 8 patients with mild hemophilia and 1 patient with moderate hemophilia (FVIII:C level 4.5%).CONCLUSION: Our study suggested that CWA and Min2 values might have greater discriminatory power in assessing low clotting factor activity. Further study is needed, including more patients with hemophilia A using CWA, correlation according to the severity group, a lower limit of detection for VIII:C, and a multiple one-stage assay.

Evaluation of the effects of carbon dioxide pneumoperitoneum on cardiovascular system with arterial pressure waveform analysis / 中国医师进修杂志

Objective Toinvestigate the effects of carbon dioxide pneumoperitoneum on cardiovascular system by making use of arterial pressure waveform analysis( FloTrac/Vigileo system) to observe the change of heart function of patients undergoing laparoscopy cholecystotomy. Methods Forty patients scheduled for elective laparoscopy cholecystotomy were divided into two groups with 20 cases each by random sampling.Ventilatory capacity was fixed (tidal volume was 10 ml/kg, frequency was 12 times/min) in group A and adjusted to keep arterial carbon dioxide tension (PaCO2) and end expiration carbon dioxide tension(PETCO2)in normal range in group B. The parameters, such as mean arterial pressure (MAP), cardiac output(CO),stroke volume (SV), stroke volume variability (SVV), heart rate(HR), pulse oxygen saturation (SpO2),PETCO2, PaCO2 were recorded and analyzed. Results In group A:HR,MAP,CI,SVV,PaCO2 and PETCO2 were increased at 10,30 min after pneumoperitoneum (P ＜0.05 or ＜0.01),there was no significant difference in SVV between the end of pneumoperitoneum and 5 min after intubation [(8 ±2)% vs. (9 ±3 )%](P＞ 0.05 ) ,but HR, MAP, CI,SVI,PaCO2 and PETCO2 increased significantly (P＜ 0.05 or ＜ 0.01 ). In group B: HR, MAP, CI, SVI, PaCO2 and PETCO2 at 10,30 min after pneumoperitoneum were no changes (P ＞0.05 ), SVV was higher than that at 5 min after intubation (P ＜ 0.01 ), there was no significant difference in SVV between the end of pneumoperitoneum and 5 ain after intubation [(9 ± 2)% vs. ( 10 ± 2)%] (P ＞0.05 ). HR, CI, SVI, PaCO2, PETCO2 at 30 min after pneumoperitoneum and the end of pneumoperitoneun were significantly higher in group A than those in group B (P ＜ 0.05 or ＜ 0.01 ). Conclusions During carbon dioxide pneumoperitoneum, hypercapnia can increase MAP, HR, CO,SV significantly, and intra abdominal pressure can decrease preload by hindering the reflow of inferior vena cava and abdominal viscera veins. Arterial pressure waveform analysis can promptly reflect the effects of carbon dioxide pneumoperitoneum on cardiovascular system and be in favour of adjusting the respiration parameters and managing transfusion in laparoscopic surgery.

The Accuracy of Arterial Waveform Analysis in Predicting Arterial Lesions Diagnosed by CT Angiography in Symptomatic Patients

PURPOSE: CT angiography (CTA) is established as a standard method for the evaluation of patients with peripheral arterial disease. However, there are some drawbacks including overestimation of stenotic lesions as well as dye toxicity and allergic reactions and renal function impairment. Arterial waveform analysis (AWA) is widely accepted as a diagnostic as well as a screening tool in the vascular laboratory. The purpose of this study was to determine the diagnostic accuracy of the AWA compared to the CTA. METHOD: One hundred thirty-eight AWA procedures were performed among symptomatic patients in our laboratory between October 2004 and February 2007. Sixty patients were entered into the study; they were eligible to have AWA and CTA synchronously. There were 5 women and 55 men with an average age of 64 years. The disease entities were atherosclerosis in 53, Burger's disease in three, popliteal entrapment in 2, arterial embolism in 1 and vascular trauma in one. Continuous-wave Doppler velocity waveforms were recorded at the common femoral, popliteal and dorsal pedal and posterior tibial arterial levels with compression cuffs. Four hundred and eighty segmental interpretations were analyzed and compared with the CTA findings. RESULT: The sensitivity of the AWA to detect iliac, femoropopliteal and tibial lesions were 93.8%, 64.4% and 88.4% respectively. The specificity of the AWA for the iliac, femoropopliteal and tibial lesions were 87.3%, 93.4% and 95.6% respectively. Overall, the accuracy of the AWA was 88.9% compared to the CT findings. Additional exercise AWA improved the results from 82.8 % to 88.6% for the overall sensitivity of the AWA. The 20 false positives included technical problems in 14 and reference errors (CTA) in six that were due to calcifications. There were 33 false negatives mostly from cases with stenosis and good collaterals. CONCLUSION: The results of this study showed that the AWA was a valuable method for the prediction of hemodynamically significant arterial lesions. The addition of highly skilled operators and a protocol including a high thigh cuff application might improve the accuracy of this diagnostic method.

A New Marker as Perinatal Predictor: Notch Index of Uterine Artery Doppler Velocimetry / 대한산부인과학회잡지

Uterine Artery Doppler velocimetry is widely applied to predict pregnancy outcomes.Recent studies of uterine artery early diastolic notch demonstrate that it is good marker forfetal well-being. The early diastolic notch represents the reflected wave of uteroplacentalcirculation. The degree of back flow is reflected by the depth of the notch. The authorspropose a new Doppler parameter, notch index(early diastolic velocity/maximum diastolicvelocity) which is a better indicator of adverse perinatal outcomes than the isolated findingof an early diastolic notch. Its ability to predict adverse perinatal outcomes was evaluatedin 121 pregnant women beyond the 28th weeks of gestation showing early diastolic notch.The incidence of adverse perinatal outcome(five minute Apgar score<7, cesarean sectiondue to fetal distress, admission to neonatal intensive care unit, or perinatal death) was 100% when the notch index was below 0.7. When the notch index range was 0.7~0.8, 0.8~0.9and greater than 0.9, the incidence of adverse perinatal outcome was 72.4%, 46.6%, and 25%, respectively. This study suggests that notch index could be used as new a marker topredict adverse perinatal outcome.