What does ED95 (Effective Dose 95) of a local anesthetic mean?

From the Guidelines

ED95 (Effective Dose 95) of a local anesthetic refers to the minimum dose required to produce effective anesthesia in 95% of patients. This is a critical pharmacological parameter used to determine appropriate dosing for clinical practice. For example, according to a study by Van de Velde et al. cited in 1, the ED95 values for bupivacaine, levobupivacaine, and ropivacaine are 3.3 mg, 5.0 mg, and 4.8 mg, respectively, when combined with 1.5 lg sufentanil. Understanding the ED95 helps clinicians select the optimal dose that will be effective for most patients while minimizing the risk of toxicity.

Key Points to Consider

• The ED95 varies depending on the specific anesthetic agent, route of administration, and the type of nerve block or procedure being performed.
• Clinicians typically use doses at or slightly above the ED95 to ensure adequate anesthesia while maintaining a margin of safety below toxic levels.
• The use of local anesthetic and opioid combinations, which are more likely to be used in clinical practice, has been investigated, with studies such as Whitty et al. cited in 1 finding that 1.75 mg bupivacaine with 15 µg fentanyl produced reliable analgesia in labor.
• The addition of sufentanil to local anesthetics has also been investigated, with the intrathecal potency ratio of sufentanil to fentanyl being 4.4:1, as cited in 1.

Clinical Implications

• The ED95 is a crucial parameter in determining the optimal dose of local anesthetics, and its value can guide clinicians in selecting the most effective and safe dose for their patients.
• The ED95 can vary significantly between different local anesthetic agents, and clinicians should be aware of these differences when selecting a local anesthetic for a particular procedure.
• The use of opioid combinations with local anesthetics can enhance analgesia, but clinicians should be cautious of the potential for adverse effects, as cited in 1.

From the Research

Definition of ED95

• ED95, or Effective Dose 95, refers to the dose of a local anesthetic required to produce a desired effect in 95% of patients 2, 3.
• This concept is crucial in determining the optimal dose of local anesthetics for various medical procedures, minimizing the risk of toxicity and ensuring effective pain management.

Calculation of ED95

• The ED95 is typically calculated using dose-finding studies, which involve administering different doses of the local anesthetic to patients and measuring the response 2, 3.
• The up-down method and random allocation design are common dose-finding strategies used to determine the ED50 (effective dose in 50% of patients) and ED95 2, 3.
• The calculated ED95 values can vary depending on the specific local anesthetic, patient population, and medical procedure being performed 2, 3.

Clinical Significance of ED95

• Knowing the ED95 of a local anesthetic is essential for clinicians to determine the optimal dose for a particular procedure, balancing the need for effective pain management with the risk of toxicity 2, 3.
• Using doses at or below the ED95 can help minimize the risk of systemic toxicity and other adverse effects, while ensuring adequate pain relief for patients 4, 2.
• The ED95 can also serve as a guide for adjusting doses in patients with specific conditions or factors that may affect the pharmacokinetics or pharmacodynamics of the local anesthetic 5, 4.