The effect of inhaled anesthetics on the platelet aggregation and the ligand-binding affinity of the platelet thromboxane A2 receptor

The Role of Anesthetic Selection in Perioperative Bleeding

Perioperative bleeding is one of the major comorbidities associated with surgery. While anesthesia is a critical component to perform surgery, a number of clinical studies supported the contribution of anesthetic drugs to perioperative bleeding. Here, we reviewed the literature on this topic including the underlying mechanism and discussed the future direction on coagulation research in anesthesia.

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.

Negative pressure pulmonary edema-related diffuse alveolar hemorrhage associated with Sevoflurane and cigarette smoking

Negative-pressure pulmonary edema (NPPE)-related diffuse alveolar hemorrhage (DAH) is an underdiagnosed clinical entity seen with alveolar capillary damage. The pathophysiology of type I NPPE is generation of a negative pleural pressure against an upper airway obstruction. We suspect this process was facilitated by preexisting alveolar damage with smoking and administration of the irritating and coagulopathic inhaled anesthetic sevoflurane. We present a case of a healthy 31-year-old man who developed postoperative hemoptysis, diffuse ground-glass opacity and infiltrates on computed tomography (CT) of the chest, anemia, and hypoxic respiratory failure. A diagnosis of DAH was made and a serologic workup for systemic disorders including vasculitis and connective tissue diseases was negative. The patient rapidly improved with supportive care and had complete resolution of his bilateral infiltrates on repeat chest x-ray two weeks later. Our literature review identified three cases of DAH in the setting of sevoflurane administration. Our case illustrates the importance of including NPPE-related DAH on the differential of post-operative hemoptysis, especially in association with sevoflurane administration and a history of cigarette smoking.

Volatile anesthetics, not intravenous anesthetic propofol bind to and attenuate the activation of platelet receptor integrin αIIbβ3

Background

In clinical reports, the usage of isoflurane and sevoflurane was associated with more surgical field bleeding in endoscopic sinus surgeries as compared to propofol. The activation of platelet receptor αIIbβ3 is a crucial event for platelet aggregation and clot stability. Here we studied the effect of isoflurane, sevoflurane, and propofol on the activation of αIIbβ3.

Methods

The effect of anesthetics on the activation of αIIbβ3 was probed using the activation sensitive antibody PAC-1 in both cell-based (platelets and αIIbβ3 transfectants) and cell-free assays. The binding sites of isoflurane on αIIbβ3 were explored using photoactivatable isoflurane (azi-isoflurane). The functional implication of revealed isoflurane binding sites were studied using alanine-scanning mutagenesis.

Results

Isoflurane and sevoflurane diminished the binding of PAC-1 to wild-type αIIbβ3 transfectants, but not to the high-affinity mutant, β3-N305T. Both anesthetics also impaired PAC-1 binding in a cell-free assay. In contrast, propofol did not affect the activation of αIIbβ3. Residues adducted by azi-isoflurane were near the calcium binding site (an important regulatory site termed SyMBS) just outside of the ligand binding site. The mutagenesis experiments demonstrated that these adducted residues were important in regulating integrin activation.

Conclusions

Isoflurane and sevoflurane, but not propofol, impaired the activation of αIIbβ3. Azi-isoflurane binds to the regulatory site of integrin αIIbβ3, thereby suggesting that isoflurane blocks ligand binding of αIIbβ3 in not a competitive, but an allosteric manner.

Haematological effects of anaesthetics and anaesthesia

Halothane is still unique in its ability to inhibit platelet aggregation and to increase bleeding time in vivo at clinical concentrations, although sevoflurane inhibits platelet aggregation induced by weak agonists. Propofol itself, but not its fat emulsion, inhibits platelet aggregation and suppresses calcium mobilization. Extradural anaesthesia has been shown to prevent hypercoagulability during the perioperative period. Aprotinin reduces both blood loss and the incidence of blood transfusion during major orthopaedic and cardiac surgery.