We thank Dr. M. del-Rio-Vellosillo et al.  for addressing our article .
We wish to respond to their questions.
In our study, intravascular (iv) solutions and injection rates were the same in both groups. We did not administer special iv pre-loading. Intrathecal injections were carried out for 20 s without barbotage or aspiration.
The methods used by our group and by del-Rio-Vellosillo et al. were different as it relates to the dose of local anesthetic and patient position. The most important methodological difference affecting the level of anesthesia and the block duration times between the two studies is the dose of local anesthetic. In our study, 15 mg of bupivacaine or levobupivacaine was administered and, in their study, 12.5 mg was administered.
In our study, spinal anesthesia was administered with the patient in the left lateral decubitus position with a 25-gauge Quincke needle at the L3–L4 interspace. In their study, local anesthetics were administered intrathecally with a 29-gauge Quincke needle at the L3–L4 interspace while the patient was in a seated position.
It is important to note that the patient population was different in the two studies. Del-Rio-Vellosillo et al. studied young patients who underwent arthroscopic knee operations, while our study included patients suffering from back and leg pain with lumbar disc herniation. Due to the differences in the patient groups, patient positions, doses of local anesthetic, and spinal needle size, it is not appropriate to compare the results of the two studies. Instead, the results should be evaluated separately. We believe that the dose of local anesthetic and the position of the patient are the two major factors in understanding why there are differences in the results of the two studies .