Propofol-based sedation in gastrointestinal endoscopy: getting safer and safer

Efficacy and safety of propofol target-controlled infusion combined with butorphanol for sedated colonoscopy

BACKGROUND

Propofol is a short-acting, rapid-recovering anesthetic widely used in sedated colonoscopy for the early detection, diagnosis and treatment of colon diseases. However, the use of propofol alone may require high doses to achieve the induction of anesthesia in sedated colonoscopy, which has been associated with anesthesia-related adverse events (AEs), including hypoxemia, sinus bradycardia, and hypotension. Therefore, propofol co-administrated with other anesthetics has been proposed to reduce the required dose of propofol, enhance the efficacy, and improve the satisfaction of patients receiving colonoscopy under sedation.

AIM

To evaluate the efficacy and safety of propofol target-controlled infusion (TCI) in combination with butorphanol for sedation during colonoscopy.

METHODS

In this controlled clinical trial, a total of 106 patients, who were scheduled for sedated colonoscopy, were prospectively recruited and assigned into three groups to receive different doses of butorphanol before propofol TCI: Low-dose butorphanol group (5 μg/kg, group B1), high-dose butorphanol group (10 μg/kg, group B2), and control group (normal saline, group C). Anesthesia was achieved by propofol TCI. The primary outcome was the median effective concentration (EC50) of propofol TCI, which was measured using the up-and-down sequential method. The secondary outcomes included AEs in perianesthesia and recovery characteristics.

RESULTS

The EC50 of propofol for TCI was 3.03 μg/mL [95% confidence interval (CI): 2.83-3.23 μg/mL] in group B2, 3.41 μg/mL (95%CI: 3.20-3.62 μg/mL) in group B1, and 4.05 μg/mL (95%CI: 3.78-4.34 μg/mL) in group C. The amount of propofol necessary for anesthesia was 132 mg [interquartile range (IQR), 125-144.75 mg] in group B2 and 142 mg (IQR, 135-154 mg) in group B1. Furthermore, the awakening concentration was 1.1 μg/mL (IQR, 0.9-1.2 μg/mL) in group B2 and 1.2 μg/mL (IQR, 1.025-1.5 μg/mL) in group B1. Notably, the propofol TCI plus butorphanol groups (groups B1 and B2) had a lower incidence of anesthesia AEs, when compared to group C. Furthermore, no significant differences were observed in the rates of AEs in perianesthesia, including hypoxemia, sinus bradycardia, hypotension, nausea and vomiting, and vertigo, among group C, group B1 and group B2.

CONCLUSION

The combined use with butorphanol reduces the EC50 of propofol TCI for anesthesia. The decrease in propofol might contribute to the reduced anesthesia-related AEs in patients undergoing sedated colonoscopy.

The median effective concentration (EC50) of propofol with different doses of fentanyl during colonoscopy in elderly patients

BACKGROUND

Propofol and fentanyl are the most widely administered anesthesia maintaining drugs during colonoscopy. In this study, we determined the median effective concentration (EC50) of propofol required for colonoscopy in elderly patients, and the purpose of this study was to describe the pharmacodynamic interaction between fentanyl and propofol when used in combination for colonoscopy in elderly patients.

METHODS

Ninety elderly patients scheduled for colonoscopy were allocated into three groups in a randomized, double-blinded manner as below, F0.5 group (0.5 μg.kg(-1) fentanyl), F1.0 group (1.0 μg.kg(-1) fentanyl) and saline control group. Anaesthesia was achieved by target-controlled infusion of propofol (Marsh model, with an initial plasma concentration of 2.0 μg.ml(-1)) and fentanyl. Colonoscopy was started 3 min after the injection of fentanyl. The EC50 of propofol for colonoscopy with different doses of fentanyl was measured by using an up-and-down sequential method with an adjacent concentration gradient at 0.5 μg.ml(-1) to inhibit purposeful movements. Anaesthesia associated adverse events and recovery characters were also recorded.

RESULTS

The EC50 of propofol for colonoscopy in elderly patients were 2.75 μg.ml(-1) (95% CI, 2.50-3.02 μg.ml(-1)) in F0.5 group, 2.05 μg.ml(-1) (95% CI, 1.98-2.13 μg.ml(-1)) in F1.0 group and 3.08 μg.ml(-1) (95% CI, 2.78-3.42 μg.ml(-1)) in control group respectively (P < 0.05). Patients in the F1.0 group had a significantly longer awake time and length of hospital stay than those in control group (P < 0.05).

CONCLUSION

Increasing doses of fentanyl up to 1.0 μg.kg(-1) reduces the propofol EC50 required for elderly patients undergoing colonoscopy, and there was no significant difference in anaesthesia associated adverse events but prolonged awake and discharge time.

TRIAL REGISTRATION

Chinese Clinical Trial Registry ChiCTR15006368. Date of registration: May 3, 2015.

Inhibition of microglial activation contributes to propofol-induced protection against post-cardiac arrest brain injury in rats

It has been suggested that propofol can modulate microglial activity and hence may have potential roles against neuroinflammation following brain ischemic insult. However, whether and how propofol can inhibit post-cardiac arrest brain injury via inhibition of microglia activation remains unclear. A rat model of asphyxia cardiac arrest (CA) was created followed by cardiopulmonary resuscitation. CA induced marked microglial activation in the hippocampal CA1 region, revealed by increased OX42 and P2 class of purinoceptor 7 (P2X7R) expression, as well as p38 MAPK phosphorylation. Morris water maze showed that learning and memory deficits following CA could be inhibited or alleviated by pre-treatment with the microglial inhibitor minocycline or propofol. Microglial activation was significantly suppressed likely via the P2X7R/p-p38 pathway by propofol. Moreover, hippocampal neuronal injuries after CA were remarkably attenuated by propofol. In vitro experiment showed that propofol pre-treatment inhibited ATP-induced microglial activation and release of tumor necrosis factor-α and interleukin-1β. In addition, propofol protected neurons from injury when co-culturing with ATP-treated microglia. Our data suggest that propofol pre-treatment inhibits CA-induced microglial activation and neuronal injury in the hippocampus and ultimately improves cognitive function. We proposed a possible mechanism of propofol-mediated brain protection after cardiac arrest (CA). CA induces P2X7R upregulation and p38 phosphorylation in microglia, which induces release of TNF-α and IL-1β and consequent neuronal injury. Propofol could inhibit microglial activation and alleviate neuronal damage. Our results suggest propofol-induced anti-inflammatory treatment as a plausible strategy for therapeutic intervention in post-CA brain injury.