Objective:
The density of local anesthetics (LA) and opioids may be influenced by the temperature of the solution. The aim of the study is to analyze the density of LA/opioid mixtures at different temperatures.
Methods:
Densities of LA/opioid mixtures that are used in spinal anesthesia such as bupivacaine 0.5%, bupivacaine hyperbaric 0.5%, levobupivacaine 0.5%, prilocaine 2%, lidocaine 2%, articaine 2%, fentanyl and morphine were measured. The measurements were made using a picnometer at 5°, 10°, 15°, 20°, 25°, 30° and 37°C temperatures.
Results:
The densities of the LA/opioid mixtures except bupivacaine hyperbaric 0.5% were hypobaric at 37°C while their densities were hyperbaric at 25°C and colder temperatures. Adding fentanyl to local anesthetics decreased the density of the mixtures, while adding morphine increased the density of the mixtures except for bupivacaine hyperbaric 0.5%.
Conclusion:
Densities of LA/opioid mixtures increase by cooling from 37°C to 5°C. The addition of opioids in LA changes the densities of LAs.
Keywords: Local anesthetic, opioids, temperature