Comparative Study between Intravenous and Intrathecal Dexmedetomidine in Spinal Anaesthesia in Patients Undergoing Elective Infra-Umbilical Surgery: The Effect on Haemodynamic Parameters and Postoperative Analgesia
Authors: Abdellatif Samia Abdelmohsen , Ghaly Safaa Ishak , Habib Mariam Kamal , Mahmoud Afnan Sameh Soliman 
Published: August 2023

Abstract

Background
One of the main objectives of anaesthesia is to alleviate the patient’s pain and agony, by ensuring the performance of surgical procedures without any discomfort. Elimination of postoperative pain is indispensable due to the central, peripheral and immunological stress response to tissue injury. So there is a need for extended analgesia without any side effects to achieve this goal. The use of opioids in intrathecal or epidural anaesthesia has become common to increase postoperative analgesia. However, opioid-induced side effects, such as respiratory depression, nausea, vomiting, urinary retention and pruritus, limit their use.

Objective
The objective of this study was to compare the efficacy of intrathecal dexmedetomidine as an adjuvant to hyperbaric bupivacaine to the intravenous route in patients who are undergoing elective infra-umbilical surgeries under spinal anaesthesia. The duration of analgesia and effect on haemodynamic parameters were evaluated. Moreover, undesirable side effects along with the effect on Ramsay sedation score were studied.

Patients and Methods
The purpose of this study was to evaluate the effect of intravenous versus intrathecal dexmedetomidine with subarachnoid anaesthesia in patients undergoing elective infraumbilical surgery. The duration of analgesia and effect on haemodynamic parameters were compared. Moreover, undesirable side effects along with the effect on Ramsay sedation score were studied. Hundred patients were randomly allocated into two equal groups (50 patients): group (A) and group (B). Group A received 3 ml of bupivacaine 0.5% plus 0.5 ml of normal saline (Total volume: 3.5 ml) along with 1µg/kg intravenous dexmedetomidine 10 minutes before the blockade. Group B received 3 ml of bupivacaine 0.5% plus intrathecal 5 µg dexmedetomidine (Precedex ©) diluted in normal saline up to the volume of 0.5 ml (Total volume: 3.5 ml).

Results
The results of the study revealed that the duration of the motor blockade was significantly longer in intrathecal than intravenous group (253.80 ± 20.94 vs. 205.00 ± 19.08; P &lt; 0.001). Also, the duration of the recovery time of sensory blockade in the intrathecal group was significantly longer than those of the intravenous group (230.48 ± 17.21 vs. 181.48 ± 21.12; P &lt; 0.001). The incidence of bradycardia was equivalent in both the groups. Although, the incidence of hypotension was greater in Group A (34.0%) in comparison to Group B (26.0%), it was not statistically significant (P &gt; 0.05). Pain intensity especially at t6 and t12 was significantly lower in the intrathecal group as compared with the intravenous group (3.5 versus 5 at t6 and 2 versus 3 at t12, respectively). Intravenous dexmedetomidine provided a higher intraoperative sedation level and both routes provided a similar sedation level in the postoperative period. The mean dose of diclofenac consumption over a period of 24 h was less in the intrathecal group as compared to the intravenous group (100.30 ± 21.63 mg vs. 135.80 ± 23.02 mg respectively, P = 0.000)

Conclusion
Intrathecal dexmedetomidine prolonged the duration of sensory and motor blockade along with the postoperative analgesia, compared to IV dexmedetomidine without any significant adverse effects and hemodynamic perturbation. So, we concluded that the addition of 5 µg dexmedetomidine as an adjuvant to 0.5% hyperbaric bupivacaine intrathecally can be a better alternative to provide a satisfactory and longer duration of analgesia as compared to IV dexmedetomidine.