Anesthesia: Essays and Researches

ORIGINAL ARTICLE
Year
: 2013  |  Volume : 7  |  Issue : 1  |  Page : 49--53

Efficacy and safety of intrathecal pentazocine as a sole anesthetic agent for lower limb surgeries


Jyothilakshmi Nair, Sunil Rajan, Jerry Paul, Susamma Andrews 
 Department of Anesthesiology and Critical Care, Amrita Institute of Medical Sciences, Kochi, Kerala, India

Correspondence Address:
Sunil Rajan
Department of Anesthesiology and Critical Care, Amrita Institute of Medical Sciences, Kochi, Kerala
India

Abstract

Context: The administration of opioids intrathecally as a sole anesthetic has proven to be effective in providing adequate surgical anesthesia without much hemodynamic instability. Aim: This study aims to determine the efficacy and safety of intrathecal pentazocine as a sole anesthetic drug in patients undergoing lower limb surgeries. Settings and Design: It was a randomized single blinded study conducted in 60 patients undergoing lower limb surgeries. Subjects and Methods: The patients were randomly divided into 2 groups of 30 patients in each group. Group A received 2 ml (60 mg) intrathecal pentazocine and Group B received 2 ml intrathecal 0.5% bupivacaine heavy before surgery. Duration of surgery, onset of sensory, and motor blockade and their duration, heart rate (HR), mean arterial pressure (MAP), and time for first rescue analgesia were statistically analyzed. Results: Group B showed a statistically significant earlier onset of sensory (2.54 ± 0.87 vs. 3.66 ± 1.10 min) and motor blocks (2.22 ± 0.77 vs. 3.29 ± 1.06 min).The majority of patients in the group A (30%) attained the highest level of sensory block of T11, whereas the majority in group B (33.3%) attained the highest level of sensory block of T8. Majority in the Group A (60%) showed a motor block of Bromage scale Grade III at the beginning of surgery, whereas the majority in Group B (80%) showed a motor block of Bromage scale Grade IV. Duration of sensory block was significantly prolonged in group B (124.33 ± 14.84 vs. 115.60 ± 18.39 min). However, duration of motor blockade was similar in both groups. Group B patients required first analgesia earlier than Group A (5.24 ± 1.98 h vs. 2.48 ± 0.51 h) which was significant. There was no difference between groups with regard to HR intra-operatively. On comparison of the pre-induction MAP between 2 groups, there was no difference. But later on at 1, 3, 5 min intervals, the MAP was less in group B. But at 10 and 15 min there was no significant difference between groups. The significantly reduced MAP in group B was evident again at 30, 45, and 60 min. There was no difference between groups at 90 and 120 min. Group B required first analgesia earlier than group A which was statistically significant. Conclusions: Because of adequate surgical anesthesia, intraoperative hemodynamic stability and prolonged post-operative analgesia, we recommend the use of intrathecal pentazocine as a sole anesthetic agent for lower limb surgeries.



How to cite this article:
Nair J, Rajan S, Paul J, Andrews S. Efficacy and safety of intrathecal pentazocine as a sole anesthetic agent for lower limb surgeries.Anesth Essays Res 2013;7:49-53


How to cite this URL:
Nair J, Rajan S, Paul J, Andrews S. Efficacy and safety of intrathecal pentazocine as a sole anesthetic agent for lower limb surgeries. Anesth Essays Res [serial online] 2013 [cited 2019 Dec 10 ];7:49-53
Available from: http://www.aeronline.org/text.asp?2013/7/1/49/113989


Full Text

 Introduction



Background

Used alone or as adjuncts, opioids deposited intrathecally is in common practice in treatment of acute pain. [1] Intrathecal pentazocine has been shown to produce sufficient analgesia and motor blockade for surgical procedures below umbilicus with motor paralysis and prolonged post-operative analgesia.

Aim of this study was to evaluate the efficacy and safety of intrathecal pentazocine for surgical anesthesia in patients undergoing lower limb surgeries.

 Subjects and Methods



The study was conducted as a prospective, randomized, double blinded one during the period June 2007 to December 2009, in 60 ASA I to III patients of age 20-60 years undergoing lower limb surgeries, lasting not more than 2 h. The patients were randomly allocated in two equal groups by a closed envelope technique into Group A and Group B.

After keeping patients NPO for 6 h, in odd ratio preloading was done with ringer lactate solution 15 ml/kg of body weight. Subarachnoid block was performed with 23 G Quincke's needle in the L3-L4 interspace in the lateral position and the study drug was injected. Group A received 2 ml of pentazocine (30 mg/ml) and Group B received 2 ml of 0.5% bupivacaine heavy solution intrathecally. Patients were immediately placed in the supine position. Intra operatively, no sedation or analgesia was given to any of the patients.

Onset of sensory analgesia was monitored from the time of intrathecal injection to the level of sensory block achieved around T10 level. Duration of analgesia was assessed from the time of sensory level achieved to the time of regression of two dermatomes or the time to start of alternative modes of analgesia. Total duration of post-operative analgesia was determined by assessing pain half hourly up to 6 h and then hourly for 12 h. Degree of motor blockade was assessed using bromage scale. Duration of motor blockade was assessed from the time of grade 4 power to grade 1 power.

Heart rate (HR) and mean arterial pressure (MAP) were recorded at pre-induction, at 1, 3, 5, 10, 15, 30, 45, 60, 90, and 120 min after subarachnoid block. A decrease in the MAP to more than 30% of the pre-block value was treated initially with a bolus of 250-500 ml of IV fluids followed by intravenous ephedrine in the dose of 3-6 mg, on failure to respond with intravenous fluids.

 Results



Distributions of patients in both groups were similar with respect to demographics, duration of surgery, and operative procedures. When the onset of sensory and motor blocks among two groups were compared it was found that group B showed an earlier onset of sensory (2.54 ± 0.87 vs. 3.66 ± 1.10 min) and motor blocks (2.22 ± 0.77 vs. 3.29 ± 1.06 min), which was statistically significant [Table 1], [Figure 1]. When the highest sensory block in both groups were assessed at the beginning of surgery, it was seen that the majority of patients in the group A (30%) attained the highest level of sensory block of T11, whereas the majority in group B (33.3%) attained the highest level of sensory block of T8 [Table 2]. When the intensity of motor blockade was assessed at the beginning of surgery, it was found that the majority of patients in the Group A (60%) showed a motor block of Bromage scale Grade III, whereas the majority in Group B (80%) showed a motor block of Grade IV [Table 3].{Figure 1}{Table 1}{Table 2}{Table 3}

When the duration of sensory and motor blocks among two groups was compared it was found that the duration of sensory block was significantly prolonged in group B (124.33 ± 14.84 vs. 115.60 ± 18.39 min) (P < 0.05). However, duration of motor blockade was similar in both the groups [Table 4], [Figure 2].{Figure 2}{Table 4}

While comparing the time for first analgesia among groups, it showed that Group B required first analgesia earlier than Group A, which was statistically significant. Group A patients required first analgesia in 5.24 ± 1.98 h compared to 2.48 ± 0.51 h in Group B, [Table 5], [Figure 3].{Figure 3}

When the pre-induction HR in both groups was compared, there was no significant difference in between groups [Table 6]. When pre-induction HR was compared to HR at 1, 3, 5, 10, 15, 30, 45, 60, 90, and 120 min again it was found that group A and group B were not statistically different [Table 7], [Figure 4]. When pre-induction MAP was compared, there was no significant difference between groups [Table 8]. When the difference of the pre-induction MAP to MAP at a subsequent time intervals was compared at 1, 3, and 5 min, there was a significant difference between groups. Group B showed a greater reduction in the MAP from the pre-induction value compared to Group A. Same observations were made at 30, 45, and 60 min. At 10, 15, 90, and 120 min, the reduction in the MAP from pre-induction values were comparable in both groups [Table 9], [Figure 5].{Figure 4}{Figure 5}{Table 5}{Table 6}{Table 7}{Table 8}{Table 9}

 Discussion



The administration of opioids intrathecally as a sole anesthetic has proven to be effective in providing adequate surgical anesthesia without much hemodynamic instability. It also provides adequate post-operative pain relief. Intrathecal pentazocine exhibits all effects of the subarachnoid administration of local anesthetic including motor, sensory and sympathetic blockade. [2],[3],[4],[5]

In the present study, the upper level of sensory blockade varied around T11 in the group A, whereas it was T8 in group B. A higher sensory block in local anesthetic group could be attributed to the lesser rostral spread of pentazocine in CSF because of their higher lipid solubility. [1] There was no significant difference statistically between the two groups in terms of duration of surgical anesthesia. The duration of analgesia produced by intrathecal pentazocine exceeded considerably as compared to the duration of analgesia obtained by intrathecal bupivacaine.

Another interesting observation was that though two dermatomal regression of sensory block was more rapid the time required for the first rescue analgesia was significantly prolonged in pentazocine group as compared to bupivacaine group. This could be because of the prolonged duration of action of subarachnoid opioids as compared to local anesthetics deposited intrathecally. [6]

Significantly low MAP in Group B at 1, 3 and 5 min, probably was because local anesthetic caused more intense sympathetic blockade. At the same time, no significant difference between groups in the MAP at 10 and 15 min could be because the hypotension in group B was corrected with IV fluids or vasopressors. The significantly reduced MAP in group evident again at 30, 45 and 60 min could again be explained because of persisting local anesthetic induced hypotension. By 90-120 min, the insignificant difference in the MAP in both groups could be because, the vasodilation caused by the sympathetic blockade had started to wean off and intravascular volume had been expanded by intraoperative IV fluids. The hemodynamic stability following intrathecal pentazocine could be advantageous in high risk patients with coronary artery disease, hypovolemia and also in old age with the added advantage of prolonged post-operative analgesia.

 Conclusion



Because of adequate surgical anesthesia, intraoperative hemodynamic stability and prolonged post-operative analgesia, we recommend the use of intrathecal pentazocine as a sole anesthetic agent for lower limb surgeries.

References

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