Optimale dosering voor een ruggenprik bij kortdurende operaties.

In day-case surgery, spinal anesthesia with both rapid onset, a short duration of block and minimal side effects is preferred. Chloroprocaine (CP) is increasingly used for this purpose. So far, the optimal dose of chloroprocaine has not been clinically established for ambulatory knee arthroscopy regarding quick postoperative mobilization and patient comfort.

We will establish the optimal dose chloroprocaine for knee-arthroscopy

Sensibel block at t=2, 4, 6, 8, 10, 15, 20, 25, 30 until end of recovery

Motor block at t=5, 10, 15, 20, 25, 30, 45, 60

Pain score at inflation of the tourniquet and during surgery

• In the first part of the study, the injected dose of chloroprocaine will be varied according to the modified up-and-down sequential allocation method (UDM) established by Dixon and Massey.14,15 The dose of chloroprocaine that a patient receives is determined by the previous patient’s response. If successful anesthesia was obtained, the next dose will be decreased. Conversely, if anesthesia was not successful, the next dose is increased. Treatment allocation will take place one day before hospital admission.

• In the second part of the study, all patients receive the ED90 dose determined in the first part. This observational section is performed with a chosen sample of patients scheduled for the same type of surgery.