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Year : 2007  |  Volume : 51  |  Issue : 3  |  Page : 216-219  

Vibration sense testing to determine timing for analgesics in post operative pain relief

1 M.D., Associate Professor, Department of Anaesthesiology, G.R.Medical College & J.A.Group of Hospitals, Gwalior (M.P.), India
2 M.D., Professor & Head, Department of Anaesthesiology, G.R.Medical College & J.A.Group of Hospitals, Gwalior (M.P.), India
3 Ex-P.G.Student, Department of Anaesthesiology, G.R.Medical College & J.A.Group of Hospitals, Gwalior (M.P.), India

Date of Acceptance15-Feb-2007
Date of Web Publication20-Mar-2010

Correspondence Address:
Dilip Kothari
2-A, J. A. Hospital Campus, Gwalior
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Source of Support: None, Conflict of Interest: None

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Aim of this study was to study the vibration sense testing with 128 Hz tuning fork as a tool to determine timing for analgesic in post operative pain relief in 60 male patients who underwent inguinal herniorrhaphy under subarachnoid block (SAB). After evaluating the time interval of recovery of vibration sense after SAB in 30 patients(Group I), tramadol 100 mg IM was given once the patient actually complained of pain at the surgical site, whereas in Group II (n=30) similar dose was given with the return of vibration sense at anterior superior iliac spine (ASIS). In Group I statistically significant rise in all the cardio respiratory parameters and VAS score were found especially near to timings for first request of analgesics (TRA 1 st ) whereas in Group II all these parameters remained near to basal values except at 360 th minute. Time for second request of analgesics (TRA 2 nd ) was significantly delayed (P<0.001) in Group II (723.33 ±12.68 min) as compared to Group (358.33±9.12 min)
Our result indicates that return of vibration sense at ASIS can be used as an indication for administration of parenteral analgesic for better post operative pain relief.

Keywords: Post operative pain relief; Subarachnoid block, Tramadol; Vibration.

How to cite this article:
Kothari D, Mehrotra A, Saggar A. Vibration sense testing to determine timing for analgesics in post operative pain relief. Indian J Anaesth 2007;51:216-9

How to cite this URL:
Kothari D, Mehrotra A, Saggar A. Vibration sense testing to determine timing for analgesics in post operative pain relief. Indian J Anaesth [serial online] 2007 [cited 2020 Nov 25];51:216-9. Available from: https://www.ijaweb.org/text.asp?2007/51/3/216/61145

   Introduction Top

Regional analgesia especially SAB provides a better intra operative block of all surgical stimuli as compared to general anaesthesia or field block but once the effect of SAB is over, patient starts feeling pain which could be en­hanced especially in the patients with low pain threshold. This can be reduced by different analgesic regimens be­fore the onset of noxious input.

Vibration sense testing has been used as a tool to determine recovery of motor power and dorsal column function after central neuraxial blockade [1],[2],[3],[4]. A definite time interval exists between the return of vibration sense and pain at surgical site [5]. No clinical study has examined the role of vibration sense testing in determining the timings for analgesics in post operative pain relief. Therefore we generated a hypothesis that if a parenteral analgesic is ad­ministered with the return of vibration sense, its peak effect will coincide with the weaning of SAB thus reducing the afferent noxious input to CNS, causing hyperalgesia.

Aims of the present study were to determine:­

  1. The time of recovery of vibration sense, pin prick and pain at surgical site and timings for giving anal­gesics in post operative period.
  2. To compare the efficacy of analgesia in patients who have received analgesic on request with those given analgesics with the return of vibration sense after SAB.

   Methods Top

After obtaining the approval of our local hospital Ethi­cal Committee and written informed patient consent, 60 male individuals (ASA status I & II, and age 25-40 years) scheduled for elective inguinal herniorrhaphy were included in this study. Patients with evidence of cardiorespiratory, neurological, psychiatric, metabolic, infective and coagula­tion disorder or on chronic analgesic medication were ex­cluded from the study. All the patients were interviewed a day before to ensure intelligent verbal communication and to explain about the procedure of testing different param­eters of the study.

Group I (n=30) : Patients were assessed for the time of recovery of vibration, pinprick and pain at surgical site after SAB. Tramadol 100 mg IM was given on request of patient after surgical pro­cedure.

Group II (n=30) : Tramadol 100 mg IM was given to all patient as soon as vibration sense re­turned at ASIS.

Efficacy of tramadol was assessed by changes in RR, PR, DBP, SBP and VAS score and subsequent re­quest for further analgesics (TRA I st and TRA II nd ) in post operative period.

All the patients received premedication with atropine sulfate 0.6 mg IM 30 minutes before SAB. On arrival to the operating theatre, baseline RR, PR, SBP and DBP were recorded for three consecutive times and its mean values were recorded as base values. After preloading with 500ml of Ringer lactate solution, SAB was performed with 2ml lidocaine Hcl 5% heavy in L2-3 space. 1-1.5 litre of crys­talloid intravenous fluid was infused to maintain blood pres­sure. No analgesic or sedative drugs were given during the operation. Following the surgical procedure patients were monitored in the post operative recovery ward for the duration of the study period.

Evaluation of recovery of vibration, pinprick and pain was done every 5minutes beginning at 60 minutes after initiation of SAB. Changes in VAS score, PR, SBP, DBP & RR were recorded every 30 minutes for next 120 min­utes and then every 60 minutes up to 360 minutes.

Return of vibration sense testing was performed with 128 Hz tuning fork at anterior superior iliac spine (ASIS), tibial tuberosity (TT) and greater toe (GT). The tuning fork was applied as perpendicular as possible resting on its weight after striking on rubber pad. Patients were asked to indi­cate the moment they perceive the vibration sense.

Pinprick sensation testing was performed with 23 SWG needle at the level of ASIS and patients were asked to indicate when they perceive it.

Assessment of pain was done with VAS score of pain using a 10 cm. horizontal scale with graduation con­necting points marked as 0 means no pain and 10 means as severe as it could be. Patients were told to indicate how they felt at that moment by placing a mark on the scale.

The efficacy of post operative analgesia was calcu­lated by TRA 1 st i.e. time interval between end point of surgery and the patient's first request for analgesic and TRA 2 nd i.e. time interval between the first dose of anal­gesic and the patient's second request for analgesic.

The observation recorded in both the groups of study were tabulated and statistical analysis was carried out by us­ing analysis of variance (ANOVA) test and Student's un­paired. Value >0.05 was considered as nonsignificant (NS), <0.05 as significant(S) and<0.001 as highly significant (HS).

   Results Top

Both the groups of this study were comparable re­garding the distribution of age, sex, height, weight and type of surgery performed. No statistically significant differ­ence was observed in the basal values of RR, PR, SBP and DBP. [Table 1]

Return of vibration sense was found to be earliest at ASIS as compared to at TT and GT. Pain at surgical site and pinprick returned later. [Table 2]

As shown in [Table 3], mean (±SD) values of all the cardiorespiratory parameters in Group I have increased significantly at 90 th and 120 th minutes of study period but decreased in the following post operative period. In Group II, no significant difference in these values were found upto 300 minutes. At 360 th minute these parameters were significantly increased in both these groups.

VAS score was low in both the groups except for the near to the timing for analgesia. [Table 3]

Mean (±SD) time for further analgesia (TRA1 st and TRA2 nd ) were 102.83 ±8.5 min & 358.33 ±9.12 min and 400 ±8.7 and 723.33 ±12.68 min in Group I & II respec­tively (P<0.001).

   Discussion Top

The onset and recovery from regional block depends upon the diameter of nerve fibres involved with a particu­lar modality of sensation [3] . The fibres with a lesser diam­eter (pain, cold, touch 2-5 µm) are earliest to be blocked but last to recover whereas the thicker fibre (propriocep­tion, vibration 12-20µm) are last to be blocked but first to recover [3],[6] . Therefore, it is very clear from this established fact that a definite time interval exists between return of vibration and pain sensation. Similar observations were noted in our study. As shown in [Table 2], a safety margin of more than 20 min exists between the return of vibration sense at ASIS and actual pain at surgical site in Group-I, thus we chose the return of vibration at ASIS as a land­mark to give tramadol 100 mg IM (Group II) to prevent pain pathway sensitization.

Till 60 min patients in both the groups were under the effect of SAB, thereafter at 90 th and 120 th min values of different parameters were highly significant (P<0.001) as the patients in Group-II were completely pain free as com­pared to the Group-I where patients still had pain because they received the analgesic after the onset of pain. Then between 180 th to 360 th minutes of the study, values of all the parameters have reached near to base values but still compliance was better (low VAS Score) in Group-II as compared to Group-I (P<0.001). At 360 th min again these values were significantly higher in Group-I because the effect of tramadol has completely weaned off, whereas in Group-II, analgesic effect still persists although to a lesser degree [Table 3].

Mean time interval between TRA1 st and TRA2 nd was 255.55 min and 323.33 min in Group I& II respectively, indicating that if analgesic is given before the onset of pain, the same doses of the drugs have longer duration and bet­ter patient compliance as compared to those given after the establishment of pain.

Our results are in accordance to various authors who also have reported that if analgesic drugs are given before rather than after the onset of pain, much lesser doses are required for the same results [7], [8], [9].

Hence, we conclude that if analgesic is given with the return of vibration sense as compared to actual return of subjective pain at surgical site, then not only patient com­pliance is better (low VAS Score) but the respiratory and haemodynamic parameters also remain stable. Effect of similar dose is found to be better once the drug is adminis­tered before the onset of pain.

Since not much work has been done on this subject, we could not compare our results with others. In our opin­ion this subject still needs to be investigated at higher cen­ter, which will help in calculating the exact timings to give analgesic for post operative pain relief which is the first and foremost aim of an anaesthesiologist.

   References Top

1.Goldberg JM, Lindblom U. Standardised method of determining vibratory perception thresholds for diagnosis and screening in neurological investigation. J Neurol Neurosurg Psychiatry 1979;42:793-803.  Back to cited text no. 1
2.Bergin PS, Bronstein AM, Murray NMF, et al. Body sway and vibration perception thresholds in normal aging and in patients with polyneuropathy. J Neurol Neurosurg Psychiatry 1995;58:335-340.  Back to cited text no. 2
3.Parry MG, Fernando R, Bawa GPS, Poulton BB. Dorsal column function after epidural and spinal blockade: implications for the safety of walking following low dose regionalanalgesia for labour. Anaesthesia 1998;53:382-403.  Back to cited text no. 3
4.Schulz-Stubner S, Zingel E, Rossaint R. Vibration sense testing with a 128 Hz tuning fork as a tool to determine recovery from epidural neuraxial block. Reg Anaesth Pain Med 2001;26:518­-522.  Back to cited text no. 4
5.Rushman GB, Davies NJH, Cashman JN. Spinal analgesia: in­tradural and Extradural. In: Rushman GB, Davies NJH, Cashman JN, eds. Lee's synopsis of anaesthesia. Butterworth Heinmann, 1999:679.  Back to cited text no. 5
6.Ganong WF. Excitable tissue: nerve. In: Ganong WF, ed. Review of medical Physiology. Appleton and Lange 2001:58-59.  Back to cited text no. 6
7.Kehlet H. Postoperative pain relief- what is the issue? Br J Anaesth 1994;75:375-377.  Back to cited text no. 7
8.Woolf C. Somatic pain- pathogenesis and prevention. Br J Anaesth 1995;75:169 -176.  Back to cited text no. 8
9.Gottschalk A, Smith DS. New concepts in acute pain therapy: Preemptive analgesia. Am Fam Physician 2001;63: 1979-84.  Back to cited text no. 9


  [Table 1], [Table 2], [Table 3]


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