Variant-derived SARS-CoV-2 spike protein does not directly cause platelet activation or hypercoagulability.

Thrombosis has been associated with severity and mortality in COVID-19. SARS-CoV-2 infects the host via its spike protein. However, direct effects of spike proteins from SARS-CoV-2 variants on platelet activity and coagulability have not been examined. An ethically approved ex vivo study was performed under a preplanned power analysis. Venous blood was collected from 6 healthy subjects who gave prior written consent. The samples were divided into 5 groups: without spike proteins (group N) and with spike proteins derived from alpha, beta, gamma, and delta SARS-CoV-2 variants (groups A, B, C, and D, respectively). Platelet aggregability, P-selectin expression, platelet-associated complement-1 (PAC-1) binding, platelet count, and mean platelet volume (MPV) were measured in all 5 groups, and thromboelastography (TEG) parameters were measured in groups N and D. The % change in each parameter in groups A to D was calculated relative to the value in group N. Data were analyzed by Friedman test, except for TEG parameters, which were evaluated by Wilcoxon matched pairs test. P < 0.05 was considered significant. This study included 6 participants based on a power analysis. There were no significant differences in platelet aggregability under stimulation with adenosine diphosphate 5 µg/ml, collagen 0.2 or 0.5 µg/ml, and Ser-Phe-Leu-Leu-Arg-Asn-amide trifluoroacetate salt (SFLLRN) 0.5 or 1 µM in groups A-D compared to group N. There were also no significant differences in P-selectin expression and PAC-1 binding under basal conditions or SFLLRN stimulation, and no significant differences in platelet count, MPV and TEG parameters. Platelet hyperactivity and blood hypercoagulability have been reported in COVID-19 patients, but spike proteins at 5 µg/ml from SARS-CoV-2 variants (alpha, beta, gamma, delta) did not directly cause these effects in an ex vivo study. This study was approved by the Ethics Committee of Kyoto University Hospital (R0978-1) on March 06, 2020.

Platelet function of whole blood after short-term cold storage: A prospective in vitro observational study.

BACKGROUND: There is no standardized storage temperature of whole blood for acute normovolemic hemodilution (ANH). STUDY DESIGN AND METHODS: We conducted a prospective observational study to examine the difference in platelet function between short-term whole blood storage at 4 and 22°C. Venous blood (40 ml) was collected from seven healthy subjects who gave prior written consent. The samples were divided into three groups: before storage (group Pre), cold (4°C) storage (group C), and room temperature (22°C) storage (group R). Groups C and R were tested after 6 h of blood storage. Platelet aggregability, platelet factor 4 (PF4), ß-thromboglobulin (ß-TG), P-selectin expression, pH, PO2 , PCO2 , glucose, lactate, blood count, and thromboelastography (TEG) parameters were measured. The percentage change in each parameter in groups C and R was calculated using the value in group Pre as a reference. These data were then compared between groups C and R using a Wilcoxon matched pairs test. p < 0.05 was considered to be statistically significant. RESULTS: Compared with group R, group C showed significantly higher platelet aggregability with adenosine diphosphate (ADP) 2, 4, and 6 µM (all p = 0.016) and collagen 1 µg/ml (p = 0.047) stimulation, and significantly lower PF4 and ß-TG elevation (both p = 0.031), glucose consumption (p = 0.031), and lactate production (p = 0.016). The ADP channel in TEG showed a significant increase in platelet aggregation rate in group C compared to group R. DISCUSSION: Cold storage of whole blood in ANH may provide improved storage conditions for platelets and contribute to improved hemostasis compared to room temperature storage.

Utility of thromboelastogram in cardiac surgery in Jacobsen syndrome associated with platelet dysfunction: a case report.

BACKGROUND: Jacobsen syndrome is a rare genetic disorder with multiple congenital anomalies and platelet abnormalities caused by chromosome 11 deletion. CASE PRESENTATION: A 7-month-old boy with thrombocytopenia underwent ventricular septal defect closure. At the beginning of surgery, the platelet count was 168 × 103/µL, and heparinized kaolin with heparinase reaction time (HKH-R), which represents clot formation time, was prolonged at 30.4 min. Platelet transfusion was continued, and at the end of surgery, the platelet count and HKH-R values improved to 215 × 103/µL and 15 min, respectively. CONCLUSIONS: As anesthetic management of patients with abnormal platelet function, the viscoelasticity test might be useful in evaluating hemostatic capacity.

Use of remimazolam in living donor liver transplantation: a case report.

BACKGROUND: Remimazolam is an intravenous ultra-short-acting benzodiazepine with the benefit of hemodynamic stability, including blood pressure and pulse rate. We report a case in which remimazolam was used in living donor liver transplantation with stable hemodynamics. CASE PRESENTATION: A 19-year-old woman underwent living donor liver transplantation due to end-stage liver disease, which is associated with a hyperdynamic state and hemodynamic instability. The patient's sister had a history of malignant hyperthermia, so we chose total intravenous anesthesia with remimazolam. Intraoperative bleeding of seven liters occurred, but she had mild intraoperative blood pressure changes, and continuous catecholamine administration was not necessary. The patient had no memories or discomfort during the surgery. CONCLUSIONS: We maintained stable hemodynamics using remimazolam for anesthetic management of a patient undergoing a liver transplantation, which is characterized by a hyperdynamic state and circulatory instability.

Agreement between continuous cardiac output measured by the fourth-generation FloTrac/Vigileo system and a pulmonary artery catheter in adult liver transplantation.

In liver transplantation for end-stage liver failure, monitoring of continuous cardiac output (CCO) is used for circulatory management due to hemodynamic instability. CCO is often measured using the minimally invasive FloTrac/Vigileo system (FVS-CCO), instead of a highly invasive pulmonary artery catheter (PAC-CCO). The FVS has improved accuracy due to an updated cardiac output algorithm, but the effect of this change on the accuracy of FVS-CCO in liver transplantation is unclear. In this study, we assessed agreement between fourth-generation FVS-CCO and PAC-CCO in 20 patients aged ≥ 20 years who underwent scheduled or emergency liver transplantation at Kyoto University Hospital from September 2019 to June 2021. Consent was obtained before surgery and data were recorded throughout the surgical period. Pearson correlation coefficient (r), Bland-Altman and 4-quadrant plot analyses were performed on the extracted data. A total of 1517 PAC-CCO vs. FVS-CCO data pairs were obtained. The mean PAC-CCO was 8.73 L/min and the mean systemic vascular resistance was 617.5 dyne·s·cm-5, r was 0.48, bias was 1.62 L/min, the 95% limits of agreement were - 3.04 to 6.27, and the percentage error was 54.36%. These results show that agreement and trending between fourth-generation FVS-CCO and PAC-CCO are low in adult liver transplant recipients.

Effects of whole blood storage in a polyolefin blood bag on platelets for acute normovolemic hemodilution.

Acute normovolemic hemodilution (ANH) is a potential transfusion method for platelets, as well as for red blood cells. However, previous studies have shown that whole blood storage in ANH decreases platelet aggregability by 14.7-76.3% and that this decrease is not recovered by reinfusion. We investigated whether a new whole blood storage method for 6 h using a polyolefin bag, based on the platelet concentrates storage method, would maintain platelet function better than the conventional method using a polyvinyl chloride bag. We demonstrated that storage of whole blood in a polyolefin bag maintained ADP-induced aggregation rates at more than twofold higher than those in a polyvinyl chloride bag, and also significantly suppressed P-selectin expression, a platelet activation marker (ADP-induced aggregation rates: 24.6 ± 5.1% vs. 51.7 ± 11.5%, p = 0.002; P-selectin expression; 50.3 ± 8.4MFI vs. 31.6 ± 9.3MFI, p = 0.018). These results could be attributed to the high gas permeability of polyolefin, which lowered PCO2 and maintained a high pH with or without agitation. There were no significant changes in platelet count and red blood cell parameters due to the storage methods. Our results suggest that ANH using polyolefin bags is advantageous in improving hemostatic function compared to the conventional method.

A case of left ventricular free wall rupture after insertion of an IMPELLA® left ventricular assist device diagnosed by transesophageal echocardiography.

BACKGROUND: The IMPELLA® is a minimally invasive left ventricular assist device. We report a case in which transesophageal echocardiography (TEE) was useful in diagnosis of left ventricular rupture after IMPELLA® insertion. CASE PRESENTATION: A 75-year-old man presented to the emergency room with chest pain and underwent percutaneous coronary intervention for 100% stenosis of the left anterior descending branch #7. An IMPELLA® was inserted to stabilize the circulation, but hypotension persisted. Transthoracic echocardiography revealed increased pericardial effusion and suspicion of free wall left ventricular rupture, leading to emergency surgery. TEE revealed the IMPELLA® straying into the left ventricle apical wall and cardiac tamponade. Hemorrhage was observed from the thinning free wall and the tip of the IMPELLA® was palpable. The IMPELLA® was removed and the left ventricular wall was repaired. CONCLUSIONS: The IMPELLA® requires implantation of the tip in the left ventricle, but it should be noted that a fragile ventricular wall can be easily perforated.

Rocuronium Has a Suppressive Effect on Platelet Function via the P2Y12 Receptor Pathway In Vitro That Is Not Reversed by Sugammadex.

Rocuronium is an aminosteroid nondepolarizing neuromuscular blocker that is widely used for anesthesia and intensive care. In this study, we investigated the effect of rocuronium on human platelet functions in vitro. The effects of rocuronium on platelet aggregation, P-selectin expression, and cyclic adenosine monophosphate (cAMP) levels in platelets were measured using an aggregometer, an enzyme immunoassay, and flow cytometry, respectively. Rocuronium inhibited ADP-induced platelet aggregation, P-selectin expression and suppression of cAMP production. These effects were not antagonized by equimolar sugammadex, a synthetic γ-cyclodextrin derivative that antagonizes rocuronium-induced muscle relaxation by encapsulating the rocuronium molecule. Morpholine, which constitutes a part of the rocuronium molecule but is not encapsulated by sugammadex, inhibited ADP-induced platelet aggregation. Vecuronium, which has a molecular structure similar to that of rocuronium but does not possess a morpholine ring, had no significant effect on ADP-induced platelet aggregation. These results indicate that rocuronium has a suppressive effect on platelet functions in vitro that is not reversed by sugammadex and suggest that this effect is mediated by blockade of the P2Y12 receptor signaling pathway via the morpholine ring of rocuronium.

Use of argatroban in combination with nafamostat mesilate in open-heart surgery for a pediatric patient with heparin-induced thrombocytopenia type II: a case report.

BACKGROUND: Heparin-induced thrombocytopenia type II (HIT II) is a rare, immune-mediated complication of heparin therapy and can cause life-threatening thromboembolism. However, perioperative anticoagulation therapy for patients with a complication of HIT II has not been established. CASE PRESENTATION: A 6-year-old boy with tetralogy of Fallot underwent radical intracardiac repair with administration of argatroban at 1 year old due to positive HIT antibody. Reoperation was scheduled for pulmonary valve insufficiency, using argatroban and nafamostat mesilate as anticoagulants. Argatroban has a long onset time and the activated coagulation time (ACT) requires 7-26 h to return to the preadministration level, making hemorrhage control difficult, while half-life of nafamostat mesilate is shorter than that of argatroban. Celite ACT reflects the effects of both argatroban and nafamostat mesilate, but kaolin ACT reflects only the effect of argatroban. Due to the early termination of argatroban administration based on Celite and kaolin ACTs, ACT recovered to ≤ 200 s at 5 h after the end of argatroban administration. CONCLUSION: Celite and kaolin ACTs can be used as markers to obtain close control of the required dose of argatroban in combination with nafamostat mesilate for the management of HIT II patients.

Successful perioperative management of living-donor liver transplantation for a patient with severe methylmalonic acidemia: a case report.

BACKGROUND: Methylmalonic acidemia (MMAemia) is a rare hereditary disease affecting organic acid metabolism. It causes recurrent metabolic acidosis and secondary mitochondrial dysfunction, resulting in a poor prognosis. Liver transplantation (LT) has been performed to facilitate the metabolism of organic acids and improve the prognosis of MMAemia. However, there have been few reports on perioperative management of LT. CASE PRESENTATION: A 22-month-old female with severe MMAemia was scheduled to receive LT to relieve recurrent metabolic acidosis despite dietary and pharmacological treatment. General anesthesia was maintained without propofol or nitrous oxide, which can worsen MMAemia-induced metabolic acidosis during anesthesia for LT. Strict metabolic and respiratory management enabled the operation to be successfully performed without metabolic acidosis. CONCLUSION: Perioperative management of LT for MMAemia is challenging for anesthesiologists because of the possibility of serious metabolic acidosis. We succeeded in preventing metabolic decompensation by avoiding the use of propofol and nitrous oxide.

Bidirectional effects of dexmedetomidine on human platelet functions in vitro.

Platelets express the imidazoline (I)-receptor, I1 and I2, as well as the α2-adrenoceptor. Although dexmedetomidine, a selective α2-adrenoceptor agonist with some affinity for the I-receptor is expected to affect platelet function, the effects of dexmedetomidine on platelet functions remain unclear. In the present study, we investigated the effects of dexmedetomidine on human platelet functions in vitro. The effects of dexmedetomidine on platelet aggregation were examined using aggregometers. The formation of cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP) in platelets was measured by an enzyme immunoassay. In addition, P-selectin expression in platelets was estimated by flow cytometry. We showed that dexmedetomidine enhances platelet aggregation. But in the presence of yohimbine, an α2-antagonist, dexmedetomidine suppressed platelet aggregation. Efaroxan, an I1-antagonist, and methylene blue, a soluble guanylate cyclase inhibitor, abolished the suppressive effect of dexmedetomidine, whereas idazoxan, an I2-antagonist, showed no effect. Dexmedetomidine suppressed cAMP formation and enhanced P-selectin expression in platelets, and these effects were inhibited by yohimbine. Dexmedetomidine increased cGMP formation in platelets in the presence of yohimbine, and this increase was suppressed by efaroxan. These results demonstrated that dexmedetomidine has both enhancing and suppressive effects on human platelet functions through its action on the α2-adrenoceptor and on the I1-imidazoline receptor, respectively.

[Comparison of intrathecal morphine and buprenorphine for postoperative analgesia in cesarean delivery].

BACKGROUND: It has become a popular practice to add opioids to spinal solutions to enhance and prolong intraoperative and postoperative analgesia in cesarean section. Morphine is the opioid most widely used for this purpose, but there are few reports about intrathecal buprenorphine. We evaluated the postoperative analgesic effect of intrathecal buprenorphine compared with intrathecal morphine after cesarean section. METHODS: We retrospectively compared group B (n = 20) receiving tetracaine 10mg plus intrathecal buprenorphine 0.05 mg with group M (n = 24) receiving tetracaine 10 mg with intrathecal morphine 0.1 mg in elective cesarean section under spinal anesthesia. RESULTS: There were no significant differences between the groups in time to first postoperative supplemental analgesics, times of using postoperative supplemental analgesics and antiemetics within 24 hours after operation, and the incidence of postoperative nausea and vomiting and pruritus. CONCLUSIONS: It is concluded that intrathecal buprenorphine 0.05 mg provides similar postoperative analgesic effect with intrathecal morphine 0.1 mg without any increases of side-effects in cesarean section.

[Evaluation of the side effects of intravenous patient controlled analgesia after spine surgery].

BACKGROUND: We have adopted intrravenous patient controlled analgesia (IV-PCA) for spine surgery. We could not find reports about detailed examinations of the side effects of IV-PCA using morphine after spine surgery, so we investigated retrospectively side effects in cases using morphine IV-PCA. METHODS: Eighty-five patients underwent IV-PCA after spine surgery. The contents of PCA pump were morphine 20 mg (= 2 ml), droperidol 2 mg (= 0.8 ml), and saline 77 ml. We fixed continuous infusion at 2 ml x hr(-1), bolus infusion at 2 ml x hr(-1), and lockout time at 15 minutes. Respiration time, SpO2, blood pressure, pulse rate, nausea and vomiting, and VAS were monitored while IV-PCA was in use. When severe side effects were noticed, IV-PCA was discontinued by physician in charge. We judged discontinuation of IV-PCA as occurrence of severe side effects. RESULTS: IV-PCA was discontinued in seven patients. The causes of discontinuation were nausea and vomiting, hypotension, and bradycardia. Nausea and vomiting was the most common cause and found mostly in women. CONCLUSIONS: Because IV-PCA was discontinuated in 8.2% of patients, it was thought that its management depending on patients' personal state was necessary to utilize IV-PCA as a method of postoperative analgesia.