Anesthesia with sevoflurane, but not isoflurane, prolongs bleeding time in humans

Ethnic disparities in postpartum hemorrhage after cesarean delivery: a retrospective case-control study

Purpose

To explore the relationship of ethnicity and postpartum hemorrhage (PPH) for women who underwent cesarean delivery (CD) and examine the risk factors for PPH in distinct ethnic groups in China.

Methods

We conducted case–control studies with the maternity data from the 11,778 CD cases, in Xinjiang Uygur Autonomous Region. Initially, multivariable logistic regression was used to estimate the disparity of race-ethnicity on the risk of PPH in ethnic Han, Uygur, Hui and Kazakh. Then, we performed case–control studies within two major ethnic groups, identifying the specific risk factors for PPH.

Results

Ethnic Uygur were associated with a statistically significant increased odds [adjusted odds ratios (aOR) 2.05; 95% confidence interval (CI) 1.26–3.33] of PPH compared with ethnic Han. For subgroup analyses, in Uygur subgroup, general anesthesia (aOR 7.78; 95% CI 2.31–26.20); placenta previa (aOR 11.18; 95% CI 3.09–40.45); prenatal anemia (aOR 4.84; 95% CI 2.44–9.60); emergency surgery (aOR 4.22; 95% CI 1.95–9.13) were independently associated with PPH. In Han subgroup, general anesthesia (aOR 5.70; 95% CI 1.89–17.26); placenta previa (aOR 20.08; 95% CI 6.35–63.46); multiple pregnancy (aOR 7.21; 95% CI 1.61–32.37); body mass index (aOR 1.19; 95% CI 1.07–1.31) were the risk factors to PPH.

Conclusion

Uygur have more tendency to PPH compared to Han, and risk factors for PPH in Uygur and Han groups may differ. Knowing these differences may be meaningful when planning interventions and resources for high-risk patients undergoing cesarean delivery, and we need more research aimed at risk factors for PPH.

Low-Dose Sevoflurane May Reduce Blood Loss and Need for Blood Products After Cardiac Surgery: A Prospective, Randomized Pilot Study

Patients undergoing cardiac surgery often experience abnormal bleeding, due primarily to cardiopulmonary bypass (CPB)-induced activation of platelets. Sevoflurane may inhibit platelet activation, raising the possibility that administering it during CPB may reduce blood loss.Patients between 18 and 65 years old who were scheduled for cardiac surgery under CPB at our hospital were prospectively enrolled and randomized to receive intravenous anesthetics alone (control group, n = 77) or together with sevoflurane (0.5-1.0 vol/%) from an oxygenator (sevoflurane group, n = 76). The primary outcome was postoperative blood loss, the secondary outcome was postoperative need for blood products.Volume of blood loss was 48% lower in the sevoflurane group than the control group at 4 hours after surgery, and 33% lower at 12 hours after surgery. Significantly fewer patients in the sevoflurane group lost >700 mL blood within 24 hours (9 of 76 vs 28 of 77, P < 0.001). As a result, the sevoflurane group received significantly smaller volumes of packed red blood cells (1.25 ± 2.36 vs 2.23 ± 3.75 units, P = 0.011) and fresh frozen plasma (97 ± 237 vs 236 ± 344 mL, P = 0.004). Thus the sevoflurane group was at significantly lower risk of requiring complex blood products after surgery (adjusted odds ratio [OR] 0.34, 95% confidence interval [CI] 0.17-0.68, P = 0.002).Sevoflurane inhalation from an oxygenator during CPB may reduce blood loss and need for blood products after cardiac surgery.

Anesthetic management as a risk factor for postpartum hemorrhage after cesarean deliveries

OBJECTIVE

This population-based study aimed to compare the risk of postpartum hemorrhage (PPH) for patients who underwent cesarean section delivery (CS) with general vs spinal/epidural anesthesia.

STUDY DESIGN

We identified 67,328 women who had live singleton births by CS by linking the Taiwan National Health Insurance Research Dataset and the national birth certificate registry. Multivariate logistic regression was carried out to explore the relationship between anesthetic management type and PPH.

RESULTS

Women who received general anesthesia had a higher rate of PPH than women who received epidural anesthesia (5.1% vs 0.4%). The odds of PPH in women who had CS with general anesthesia were 8.15 times higher (95% confidence interval, 6.43-10.33) than for those who had CS with epidural anesthesia, after adjustment was made for the maternal and fetal characteristics.

CONCLUSION

The odds that women will experience cesarean PPH with general anesthesia are approximately 8.15 times higher than for women who undergo CS with epidural anesthesia.

Delayed inhibition of agonist-induced granulocyte-platelet aggregation after low-dose sevoflurane inhalation in humans

BACKGROUND

Sevoflurane can be used as sedative-analgesic drug with endothelial protective properties. We tested whether low-dose sevoflurane inhalation provides sustained inhibition of detrimental granulocyte-platelet aggregation in humans.

METHODS

Ten healthy male volunteers were enrolled in this crossover study. Each subject inhaled sevoflurane for 1 h at 0.5-1 vol % end-tidal concentration in oxygen (50 vol %). Inhaling oxygen (50 vol %) alone served as control. Venous blood samples were collected at baseline before inhalation, immediately after inhalation, and 24 h thereafter, and were used for flow cytometry to determine platelet surface marker (CD41, CD42b, CD62P/P-selectin, and PAC-1) on platelets and granulocytes and for kaolin-induced clot formation, as assessed by thromboelastography. In flow cytometry experiments, platelets were stimulated with arachidonic acid (AA, 30 microM), adenosine diphosphate (ADP, 1 microM), and thrombin receptor agonist peptide-6 (TRAP-6, 6 microM).

RESULTS

AA, ADP, and TRAP-6 markedly increased the expression of CD62P on platelets, whereas CD42b (shedding) and PAC-1 (heterotypic conjugates) expression decreased. The amount of granulocyte-platelet aggregates increased upon agonist stimulation. Low-dose sevoflurane inhalation reduced ADP-induced CD62P expression on platelets 24 h after inhalation, and inhibited the formation of granulocyte-platelet aggregates under stimulation with AA and ADP after 1 and 24 h, and with TRAP-6 after 24 h compared with control. Inhibition of granulocyte-platelet aggregates was accompanied by reduced clot firmness 24 h after sevoflurane inhalation compared with control.

CONCLUSIONS

We demonstrated for the first time that inhaling low-dose sevoflurane (<1 vol % end-tidal) inhibits agonist-induced granulocyte-platelet interactions 24 h after administration and thus counteracts thromboinflammatory processes.

Pharmacology of modern volatile anaesthetics

The volatile anaesthetics sevoflurane and desflurane feature new and promising properties. Their low blood and tissue solubility enables rapid onset of and emergence from anaesthesia, thus enhancing patient safety and comfort. This article is designed as an up-to-date review of the pharmacokinetic and pharmacodynamic properties of modern volatile anaesthetics. The first part focuses on pharmacokinetic issues such as substance properties, uptake and elimination. The second part covers the effects of inhaled anaesthetics on organ systems, with emphasis on the central nervous system, the cardiovascular system, the respiratory tract, liver and kidneys.

Effects of isoflurane, sevoflurane, and desflurane on platelet function: A prospective, randomized, single-blind, in vivo study

BACKGROUND

The primary physiologic function of platelets is to facilitate hemostasisby aggregation. Volatile anesthetics have been reported to decrease platelet aggregation in vivo and in vitro.

OBJECTIVE

The aim of this study was to investigate the hematologic effectsof the anesthetics isoflurane, sevoflurane, and desflurane on hemoglobin (Hb), hematocrit (Hct), platelet count, activated partial thromboplastin time (aPTT), prothrombin time (PT), international normalized ratio (INR), and platelet aggregation after minor surgery.

METHODS

Patients aged 20 to 60 years who were scheduled to undergominor surgery and American Society of Anesthesiologists physical status P1 or P2 (healthy or mild systemic disease) were randomized to 1 of 3 groups: 1 minimum alveolar concentration (MAC) of isoflurane, sevoflurane, or desflurane. None of the patients received premedication. Anesthesia was induced using IV thiopental 5 to 6 mg/kg, fentanyl 1 to 2 μg/kg, and vecuronium 0.1 mg/kg, and maintained with 1 MAC of isoflurane, sevoflurane, or desflurane in 66% nitrous oxide and 33% oxygen. Vecuronium 0.03 mg/kg was given when necessary for muscle relaxation. All patients were monitored throughout surgery; isotonic saline was given at a rate of 5 mL/kg · h. Hematologic studies were performed preoperatively, 15 minutes after intubation, and 1 hour after the end of surgery. Platelet aggregation tests were performed in a laboratory using a platelet function analyzer (PFA), collagen/epinephrine PFA test cartridges, collagen/adenosine diphosphate PFA test cartridges, and PFA trigger solution.

RESULTS

This prospective, randomized, single-blind, in vivo study was conducted at Gevher Nesibe Teaching Hospital, Erciyes University, Kayseri, Turkey. Thirty patients (15 men, 15 women) were randomized to the 3 treatment groups (each, n = 10). Hb, Hct, platelet count, aPTT, PT, and INR were statistically similar between all 3 groups. The measured parameters were not significantly different between the isoflurane and desflurane groups at any time point. However, in the sevoflurane group, mean (5D) platelet aggregation was significantly delayed 15 minutes after intubation and 1 hour after surgery compared with the preoperative values (collagen/epinephrine, 81.70 [9.85] seconds vs 196.20 [27.84] seconds and 115.40 [25.80] seconds; both, P < 0.05).

CONCLUSIONS

In this study of the effects of isoflurane, sevoflurane, and desflurane in patients undergoing minor surgery, clinically relevant antithrombotic effects were observed 15 minutes after intubation with all 3 drugs, although the effects in patients receiving sevoflurane were significantly greater compared with those in patients receiving isoflurane and desflurane. The antithrombotic effects of isoflurane and desflurane were not continued at 1 hour after surgery; however, the inhibitory effects of sevoflurane on platelet function were continued at 1 hour after surgery but were significantly decreased from levels found at 15 minutes after intubation.

Possible interaction between sevoflurane and Aloe vera

OBJECTIVE

To describe a patient with massive intraoperative bleeding after oral consumption of Aloe vera tablets.

CASE SUMMARY

A 35-year-old woman lost 5 L of blood during surgery as a result of a possible herb-drug interaction between Aloe vera and sevoflurane.

DISCUSSION

Aloe vera is a common herb used for antiinflammatory and antiarthritic activity, as well as antibacterial, hypoglycemic, and lipid-lowering effects. Compounds contained within Aloe vera can cause a reduction in prostaglandin synthesis, which may inhibit secondary aggregation of platelets. Sevoflurane inhibits thromboxane A(2) formation by suppression of cyclooxygenase activity, impairs platelet aggregation, and prolongs bleeding. Although the vascularity and size of the hemangioma were the most important factors for the massive intraoperative blood loss, concomitant use of sevoflurane and Aloe vera played a contributory role. An objective causality assessment revealed that this adverse event was possible as a result of the sevoflurane and Aloe vera interaction.

CONCLUSIONS

There is a potential herb-drug interaction between Aloe vera and sevoflurane based on the antiplatelet effects of these 2 agents. Herbal medications with antiplatelet potential should be discontinued before anesthesia and surgery.