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PubMed2001

Arterial and venous Thrombelastograph variables differ during cardiac surgery.

UNLABELLED: The Thrombelastograph (TEG; Haemoscope Corp., Skokie, IL) coagulation analyzer is an effective point-of-care monitor for routine clinical practice and clinical research. Prior investigators have used either arterial or venous samples of blood for TEG measurements. We conducted this prospective cohort study to determine potential differences in TEG variables between arterial and venous blood samples. Arterial and venous samples were drawn from 40 cardiac surgical patients, yielding 134 pairs for comparison. Twenty-nine comparisons (control) were between arterial and arterial samples and were not significantly different. For the arterial and venous comparisons (n = 105), mean (+/-sd) arterial and venous values were the following: reaction time, 10 +/- 2 mm vs 13 +/- 4 mm, P = 0.004; maximum amplitude, 59 +/- 9 mm vs 49 +/- 12 mm, P < 0.001; alpha angle, 61 +/- 10 degrees vs 51 +/- 14 degrees, P < 0.001; K, 5 +/- 2 mm vs 8 +/- 4 mm, P = 0.007; and lysis, 2.5 +/- 1.7 vs 2.5 +/- 2.0 (not significant), arterial versus venous, respectively. Arterial blood samples demonstrated TEG values reflecting stronger (larger maximum amplitude) and faster (shorter reaction time and K value, wider alpha angle) clot formation. The results suggest that users of TEG coagulation analyzers should be consistent with the site of blood sampling given the potential differences obtained. IMPLICATIONS: Thrombelastograph (TEG) values obtained from venous blood samples differ from values obtained from arterial blood samples. When the TEG coagulation analyzer is used for clinical purposes, it is important to be consistent in the blood collection site.

Adult↗
PubMed2001

Hemostatic changes in pediatric neurosurgical patients as evaluated by thrombelastograph.

UNLABELLED: Thromboembolic events are a known complication in neurosurgical patients. There is evidence to suggest that a hypercoagulable state may develop perioperatively. Thrombelastograph (TEG) coagulation analysis is a reliable method of evaluating hypercoagulability. We evaluated coagulation by using TEG data in pediatric neurosurgical patients undergoing craniotomy to determine whether a hypercoagulable state develops intraoperatively or postoperatively. Thirty children undergoing craniotomy for removal of a tumor or seizure focus were studied. Blood was analyzed with TEG) data by using native and celite techniques, at three time points for each patient: preoperatively after induction of anesthesia; intraoperatively during closure of the dura; and on the first postoperative day. Compared with preoperative indices, closing and postoperative celite TEG values were indicative of hypercoagulability with shortened coagulation time values (P < 0.001), prolonged alpha angle divergence values (P < 0.001), and above-normal TEG coagulation indices (P < or = 0.002). Reaction time values were shortened, and maximal amplitude of clot strength values were prolonged but did not reach statistical significance. Hypercoagulation develops early after resection of brain tissue in pediatric neurosurgical patients as assessed by using TEG data. Further studies are needed to determine the clinical significance of this hypercoagulable state. IMPLICATIONS: Hypercoagulability in postoperative neurosurgical patients has been demonstrated in the adult population, but few studies have dealt with the pediatric population. We found that children undergoing craniotomy for focal resection, lobectomy, and hemispherectomy are hypercoagulable as detected by thrombelastograph coagulation analysis. Further studies are needed to determine whether this is clinically significant.

Adolescent↗
PubMed2002

The effect of the combined administration of colloids and lactated Ringer's solution on the coagulation system: an in vitro study using thrombelastograph coagulation analysis (ROTEG.

UNLABELLED: Gelatin solutions are often given in clinical practice once the maximal dose of a median-weight hydroxyethyl starch (HES) has been reached. Colloids are usually combined with lactated Ringer's solution (RL). Whether the combined administration of colloids and/or crystalloids affects blood coagulation is not known. We diluted blood by 20%, 40%, and 60% with RL, gelatin (Gelofusin), 6% HES 130/0.4 (Voluven), and 6% HES 200/0.5 (Iso-Hes), as well as with combinations of these solutions at a ratio of 1:1 (gelatin/RL, 6% HES 130/0.4:RL, 6% HES 200/0.5:RL, 6% HES 130/0.4:gelatin, 6% HES 200/0.5:gelatin). Thereafter, blood was analyzed by using modified thrombelastograph coagulation analysis (ROTEG) and clotting time, clot formation time, and maximal clot firmness were determined. RL had the least effect on hemostasis. Gelatin administered alone impaired the coagulation system significantly less than each median-weight HES administered alone. We conclude that gelatin combined with 6% HES 200/0.5 or 6% HES 130/0.4 decreases hemostasis <6% HES 200/0.5 or 6% HES 130/0.4 administered alone. IMPLICATIONS: The effect of the combined administration of different colloids and/or crystalloids on coagulation is not known. We show that hemostasis is less impaired using a combination of gelatin and median-weight starches than using median-weight starches alone. Furthermore, the combination of lactated Ringer's solution and gelatin decreases the coagulation system to the same extent as the combination of lactated Ringer's solution and 6% hydroxyethyl starch 130/0.4.

Adult↗
PubMed2002

In vitro fertilization-induced alterations in coagulation and fibrinolysis as measured by thromboelastography.

Supraphysiologic increases in estrogen produced by in vitro fertilization (IVF) promote the expression of hemostatic markers. Although quantitative studies of individual markers have been performed during IVF, their results are conflicting and do not reveal the qualitative effect of each marker on the overall coagulation and fibrinolytic processes. Thrombelastograph (TEG) coagulation analysis, by contrast, provides a global measure of coagulation and fibrinolysis and can indicate the relative contributions of clotting factors, fibrinogen, and platelets to each process. We studied the serum estrogen concentrations and TEG variables in 24 women at the beginning and conclusion of an IVF stimulation cycle. Serum estradiol (E(2)) concentrations (mean +/- SD) increased from 26.9 +/- 8.6 to 2098 +/- 913 pg/mL (P < 0.005) at baseline and oocyte retrieval, respectively. The measured TEG indices demonstrated alterations in coagulation rather than fibrinolysis. Although significant changes were noted in both the clot formation time and the coagulation index (P < 0.005), all TEG values remained within the normal range. In addition, an increased role of fibrinogen in promoting clot strength was observed. These findings may assist in the treatment of IVF patients who ultimately develop thromboembolic complications as a result of ovarian hyperstimulation. IMPLICATIONS. The dramatic changes in estrogen produced by in vitro fertilization therapies result in hemostatic marker alterations. Thrombelastograph coagulation analysis, which provides a global assessment of these changes, demonstrated significant alterations in two coagulation indices (clot formation time, coagulation index), although all variables remained within normal limits. The relative importance of fibrinogen versus platelets in determining clot strength was observed. No significant alterations in fibrinolysis were detected.

Adult↗
PubMed2003

The influence of crystalloid and colloid replacement solutions in acute normovolemic hemodilution: a preliminary survey of hemostatic markers.

Acute normovolemic hemodilution (ANH), in which blood for autologous use is collected immediately before the onset of surgical blood loss, is a recommended autologous blood procurement technique for blood conservation. Both crystalloid and colloid replacement fluids have been used to maintain normovolemia during ANH, but few data are available to justify the use of a particular replacement fluid. Therefore, we designed a prospective, randomized study to determine if the replacement fluid choice affects various coagulation variables and perioperative blood loss. Forty adult patients, ASA physical status 1-3, scheduled for ANH during radical prostatectomy were randomly assigned to one of four replacement fluid groups: (a) Ringer's lactate, (b) 5% albumin, (c) 6% dextran 70 (DEX), or (d) 6% hetastarch (HES). After the induction of a standardized general anesthetic, all patients underwent ANH to a final hemoglobin level of 9 g/dL. Complete blood count, prothrombin time, partial thromboplastin time, fibrinogen, factors V and VIII levels, bleeding time, and thromboelastography (TEG measurements were obtained at similar time points in the procedure. When compared with baseline, activated partial thromboplastin time decreased and factor VIII levels increased in the postanesthesia care unit in both the Ringer's lactate and 5% albumin groups. The DEX and HES groups demonstrated a decrease in TEG maximum amplitude between preoperative and postanesthesia care unit measurements and TEG alpha (angle) was decreased from baseline in the DEX group. The changes in factor VIII, activated partial thromboplastin time, and TEG measurements indicate that HES and DEX may attenuate the hypercoagulability related to surgery.

Aged↗
PubMed1992

The role of desmopressin acetate in patients undergoing coronary artery bypass surgery. A controlled clinical trial with thromboelastographic risk stratification.

The role of desmopressin acetate in attenuating blood loss and reducing homologous blood component therapy after cardiopulmonary bypass is unclear. The purpose of this investigation was to identify a subgroup of patients that may benefit from desmopressin acetate therapy. One hundred fifteen patients completed a prospective randomized double-blind, placebo-controlled trial designed to evaluate the effect of desmopressin acetate (0.3 microgram.kg-1) on mediastinal chest tube drainage after elective coronary artery bypass grafting surgery in patients with normal and abnormal platelet-fibrinogen function as diagnosed by the maximal amplitude (MA) on thromboelastographic (TEG) evaluation. The 115 patients evaluated were divided into two groups based on the MA of the post-cardiopulmonary bypass TEG tracing. Group 1 (TEG:MA greater than 50 mm) consisted of 86 patients, of whom 44 received desmopressin and 42 received placebo. Twenty-nine patients had abnormal platelet function (TEG:MA less than 50 mm) and were designated as group 2. In group 2, 13 received desmopressin and 16 placebo. During the first 24 h after cardiopulmonary bypass, the placebo-treated patients in group 2 had significantly greater mediastinal chest tube drainage when compared to placebo patients in group 1 (1,352.6 +/- 773.1 ml vs. 865.3 +/- 384.4 ml, P = 0.002). In addition to increases in blood loss, group 2 placebo patients also were administered an increased number of blood products (P less than 0.05). The desmopressin-treated patients in group 2 neither experienced increased mediastinal chest tube drainage nor received increased amounts of homologous blood products when compared to those in group 1.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1999

Assessment of changes in coagulation in parturients with preeclampsia using thromboelastography.

BACKGROUND: Preeclampsia is associated with a risk of abnormal hemostasis that occurs most commonly secondary to thrombocytopenia. Thromboelastography measures whole blood coagulation and has been used to manage coagulation defects in obstetric patients. The authors conducted this investigation in a large number of preeclamptic women to assess changes in coagulation using thromboelastography. METHODS: Thromboelastography and platelet counts were performed in 52 healthy pregnant women, 140 mild preeclamptic women, and 114 severe preeclamptic women in active labor using disposable plastic cups and pins and native whole blood. In preeclamptic patients with a platelet count <100,000/mm3, conventional coagulation tests were also performed. Epidural analgesia was provided in some women when they requested pain relief. RESULTS: Fifteen percent of all preeclamptic women (38 of 254) and 2% (1 of 52) of healthy pregnant women had a platelet count <100,000/mm3. The incidence of thrombocytopenia <100,000/mm3 was 3% (4 of 140) and 30% (34 of 114) in mild preeclamptic patients and severe preeclamptic patients, respectively. Severe preeclamptic patients with a platelet count <100,000/mm3 were significantly hypocoagulable when compared to the other study groups. Ten severe preeclamptic women with a platelet count <100,000/mm3 had a maximum amplitude <54 mm (the lower limit of maximum amplitude in healthy pregnant women enrolled in this investigation). None of the mild preeclamptic women had a maximum amplitude <54 mm. Five severe preeclamptic women with a platelet count <100,000/mm3 had an abnormal coagulation profile, whereas all four mild preeclamptic women with a platelet count <100,000/mm3 had a normal coagulation profile. CONCLUSION: This study shows that severe preeclamptic women with a platelet count <100,000/mm3 are hypocoagulable when compared to healthy pregnant women and other preeclamptic women.

Adult↗
PubMed2000

Citrate storage affects Thrombelastograph analysis.

BACKGROUND: Thrombelastograph analysis (TEG) is used to evaluate blood coagulation. Ideally, whole blood is immediately processed. If impossible, blood may be citrated and assessed after recalcification. No data describe the effect of such treatment and storage on TEG parameters. METHODS: Three studies were performed in 90 surgical patients. In 30 patients, blood was citrated (1:10, 0. 129 M) and recalcified (20 microl 2 M CaCl2 to 340 microl citrated blood), and TEG was performed with native blood and after recalcification after 0, 15, and 30 min of citrate storage. In another 30 patients, TEG was performed with citrated blood recalcified immediately and after 1-72 h storage. In a third study, thrombin-antithrombin complex, prothrombin fragment 1+2, and beta-thromboglobulin were measured (using enzyme-linked immunoabsorbant assay tests) at corresponding time points. Data were compared using repeated-measures analysis of variance and post hocpaired t tests. RESULTS: TEG parameters were different in recalcified citrated blood compared with native blood (P < 0.05) and changed significantly during 30-min (P < 0.025) and 72-h (P < 0.001) citrate storage. TEG parameters measured between 1 and 8 h of citrate storage were stable. Thrombin-antithrombin complex and prothrombin fragment 1+2 values were not elevated in native blood. After 30 min of citrate storage a gradual thrombin activation was observed, as evidenced by increasing thrombin-antithrombin complex and prothrombin fragment 1+2 values (P < 0.05). beta-Thromboglobulin level was increased after 2 and 8 h of citrate storage (P < 0.01). CONCLUSIONS: Analysis of native blood yields the most reliable TEG results. Should immediate TEG processing not be possible, citrated blood may be used if recalcified after 1-8 h.

Analysis of Variance↗
PubMed2000

Low- and medium-molecular-weight hydroxyethyl starches: comparison of their effect on blood coagulation.

BACKGROUND: High-molecular-weight hydroxyethyl starch (HES) compromises blood coagulation more than medium-molecular-weight HES. The authors compared medium molecular weight HES (200 kd [HES200]) and low-molecular-weight HES (70 kd [HES70]). METHODS: In a prospective, double-blind, randomized-sequence crossover study, 22 male volunteers received 15 ml/kg HES200 and HES70. Blood samples were taken before and 5 min, 30 min, 1 h, 2 h, 4 h, 8 h, and 24 h after infusion. The following parameters were analyzed at all time points: prothrombin time, activated partial thromboplastin time, fibrinogen, factor VIII, antigenetic and functional von Willebrand factor, platelets, Thrombelastograph analysis parameters (reaction time, coagulation time, maximum amplitude, angle alpha, and clot lysis 30 and 60 min after maximum amplitude), ionized calcium, hematocrit, HES plasma concentration, molecular weight (weight average and number average), molar substitution, and polydispersity (weight average/number average). Repeated-measures analysis of variance (P < 0.05) was used to compare the response of the aforementioned parameters to the infusion of HES70 and HES200. RESULTS: Both HES solutions had a significant impact on all parameters. A slightly greater compromise with HES200 was found in activated partial thromboplastin time (P = 0.010), factor VIII (P = 0.009), antigenetic von Willebrand factor (P = 0.041), functional von Willebrand factor (P = 0.026), maximum amplitude (P = 0.008), and angle alpha (P = 0.003). No difference was established with the other parameters. HES concentration (P < 0.001), weight average (P < 0.001), number average (P < 0.001), and polydispersity (P < 0.001) were higher with HES200. There was no difference with molar substitution (P = 0.091). CONCLUSIONS: Low-molecular-weight hydroxyethyl starch (70 kd) compromises blood coagulation slightly less than HES200, but it is unclear whether this is clinically relevant.

Adult↗
PubMed2001

The effects of aprotinin on thromboelastography with three different activators.

BACKGROUND: Thromboelastography is used for assessment of hemostasis. Adherence to thromboelastography-guided algorithms and aprotinin administration each decrease bleeding and blood product usage after cardiac surgery. Aprotinin, through inhibition of kallikrein, causes prolongation of the celite-activated clotting time and the activated partial thromboplastin ratio. The aim of this study was to assess the effects of aprotinin on the thromboelastography trace. METHODS: Three activators were used in the thromboelastography: celite (which is widely established), kaolin, and tissue factor. Assessment was performed on blood from volunteers and from patients before and after cardiac surgery. RESULTS: The tissue factor-activated thromboelastography trace was unaffected by the addition of aprotinin. When celite and kaolin were used as activators in the presence of aprotinin, the reaction time (time to clot formation) of the thromboelastography trace was prolonged (P < 0.0001) and the maximum amplitude (clot strength) was decreased (P < 0.05). With celite as an activator, the addition of aprotinin decreased (P < 0.05) the thromboelastography alpha angle (rate of clot extension). The reaction time of the celite-activated trace correlated with the activated partial thromboplastin ratio (P < 0.01). The reaction time of the tissue factor-activated trace correlated with the international normalized ratio (P < 0.01). CONCLUSION: The thromboelastography trace is altered in the presence of aprotinin when celite and kaolin are used as activators but not when tissue factor is the activator.

Aprotinin↗
PubMed2001

Sevoflurane inhibits unstimulated and agonist-induced platelet antigen expression and platelet function in whole blood in vitro.

BACKGROUND: Previous studies have reported conflicting results about the effect of sevoflurane on platelet aggregation. To clarify this point, we investigated the effects of sevoflurane on platelet antigen expression and function in vitro. METHODS: Human whole blood was incubated for 1 h with 0.5 and 1 minimum alveolar concentration sevoflurane, 21% O(2), and 5% CO(2). A control sample was kept at the same conditions without sevoflurane. After stimulation with adenosine diphosphate or thrombin receptor agonist peptide 6, samples were stained with fluorochrome conjugated antibodies, and the expression of platelet glycoproteins GPIIb/IIIa, GPIb, and P-selectin, as well as activated GPIIb/IIIa, were measured with two-color flow cytometry. In addition, platelet function was assessed by means of thromboelastography and using the platelet function analyzer 100. RESULTS: Already in subanesthetic concentrations, sevoflurane inhibits unstimulated and agonist-induced GPIIb/IIIa surface expression and activated GPIIb/IIIa expression on platelets in whole blood. The agonist-induced redistribution of GPIb into the open canalicular system was also impaired by sevoflurane, whereas no effect on P-selectin expression in activated platelets could be found. Sevoflurane significantly reduced the maximum thromboelastographic amplitude. Furthermore, platelet function analyzer 100 closure times were significantly prolonged. CONCLUSION: The results show that sevoflurane significantly impairs platelet antigen expression in vitro. It is especially the inhibition of GPIIb/IIIa expression and activation that impairs bleeding time as reflected in thromboelastographic measurements and platelet function analyzer 100 closure times. The exact inhibitory mechanism remains unclear.

Anesthetics, Inhalation↗