Low-flow anesthesia: theory, practice, technical preconditions, advantages, and foreign gas accumulation

The potency and duration of action of local anesthetics (LAs) are determined by their pharmacokinetics. Pharmacokinetics describes how LAs are absorbed, distributed, metabolized, and eliminated from the body. When administered to the vascular tissues, LAs are quickly absorbed and enter the systemic circulation, reducing their localized effects. Adding vasoconstrictors such as epinephrine to LAs reduces their absorption into the systemic circulation, making them clinically effective. The...

Depending on the target organ, local anesthetics (LAs) can be administered via various routes. In surface anesthesia, LAs are applied directly to the surface of the skin or mucous membranes. It is widely used for topical skin numbing before venipuncture or minor surgical procedures. Commonly used surface local anesthetics are lidocaine or benzocaine sprays or creams. Surface anesthesia occurs within 5 minutes and lasts for about 60 minutes. One of the main disadvantages of topical anesthesia is...

Spinal anesthetics are given during lower abdomen and limb surgeries to block sensory and motor neurons. They are administered in the mid to low lumbar regions, primarily acting on the cauda equina's nerve roots. The blockade level depends on the local anesthetic (LA) concentration. Usually, low LA concentrations are sufficient to block sensory fibers, while only high LA concentrations block motor fibers. Other factors like injection volume and speed, the patient's posture, and the drug...

Anesthesia is a medical procedure that uses drugs for CNS suppression to enable painless surgeries and procedures. The selection of anesthetics is influenced by their pharmacokinetic properties, side effects, and patient characteristics. Various types of anesthesia include general, local, regional, spinal, and inhalational.
General anesthesia induces unconsciousness in the whole body, while the others target specific areas or sensations. It is administered to minimize adverse effects, maintain...

Various sedation levels offer significant advantages in facilitating procedural interventions for patients undergoing medical or invasive surgical procedures. These levels span from anxiolysis to general anesthesia, providing a spectrum of sedative effects to cater to specific patient needs. Anxiolysis reduces anxiety and is achieved through minimal sedation, enabling patients to remain awake and responsive while feeling more at ease during the procedure. This level can benefit minor...

Inhalation anesthetics are drugs that induce general anesthesia upon inhalation. They work by increasing the sensitivity of GABAA receptors or inhibiting NMDA receptors, leading to a decrease in central nervous system activity. The depth of anesthesia can be rapidly adjusted by changing the concentration of the inhaled gas. Some common examples of inhalational anesthetics include volatile liquids like isoflurane, desflurane, sevoflurane and gases like xenon and nitrous oxide. Isoflurane, a...