Hemodynamic changes and post-operative complications with use of caudal bupivacaine and bupivacaine-dexmedetomidine combination for post-operative analgesia

 

Attar Tausif^1*, Kamble Raviraj², Agrawal Pushpa³, Kulkarni Vaishnavi⁴

 

¹Assistant Professor, ³Professor and HOD, ⁴Associate Professor, Department of Anaesthesia, Dr. V.M. Government Medical College, Solapur, Maharashtra, INDIA.

²Senior Resident, Department Of Anaesthesia, Government Medical College, Miraj, Maharashtra, INDIA.

Email: join_tausif@yahoo.co.in

 

Abstract               Background: Caudal anaesthesia is a commonly performed regional block in children for abdominal and lower limb surgeries. The use of adjuncts like Dexmedetomidine can effectively help in reduction of the dose and an increase in duration of action of the local anaesthetic agent like bupivacaine. Aim: To study addition of Dexmedetomidine to bupivacaine with regards to hemodynamic changes and post-operative complications. Material and Methods: A total of 60 patients of 2-10 years of age posted for routine infraumbilical surgerieswere randomly divided in to two groups. Group A- (Control group) received 0.25% Bupivacaine. Group B - (Study group) received 0.25% Bupivacaine + 1μg/kg Dexmedetomidine. Haemodynamic parameters in the form of pulse rate, blood pressure, SpO2, respiratory rate were observed. Results: The difference between the two groups for change in mean arterial pressure was statistically significant, but the patients were haemdynamically stable. Two patients from group A and one patient from group B had vomiting in the postoperative period. While two patients from both group A and group B complained of failure to pass urine at 6 hrs. Conclusion: The addition of dexmedetomidine in the dose of 1μg/kg to 0.25% bupivacaine for caudal blockade significantly prolongs the duration of analgesia without any significant hemodynamic changes and is safe for use in paediatric patients.

Key Words: Paediatrics, caudal block, bupivacaine, Dexmedetomidine, complications.

INTRODUCTION

Caudal anaesthesia is a commonly performed regional block in children for abdominal and lower limb surgeries. The caudal block can provide analgesia for surgeries up to and including the umbilicus. It is relatively simple technique with good success rate.^1,2 The main disadvantage of caudal block is duration of action after a single injection which is limited by duration of action of local anaesthetics.³ Many local anaesthetic drugs of variable concentration are used. But the mean duration of surgical analgesia provided by long acting anaesthetic drug like bupivacaine is only for 4-8 hrs during single shot caudal procedure. So, prolongation is achieved by addition of various adjuvants like opioids, ketamine, neostigmine, midazolam etc. Caudal opioids have advantages of prolonging the duration of analgesia over bupivacaine alone, but has side effects such as nausea, vomiting, pruritis and late respiratory depression.^4-6 Dexmedetomidine is a highly selective alpha-2 agonist, especially for the 2A subtype of this receptor, which causes it to be a much more effective sedative and analgesic agent without undesirable cardiovascular effects from alpha-1 receptor activation.⁷Hence, an attempt was made to study addition of dexmedetomidine, an alpha-2 adrenergic receptor agonist with striking lack of respiratory depressant effect to bupivacaine with regards to hemodynamic changes and post-operative complications.

MATERIAL AND METHODS
The present study included 60 patients in the age group of 2 to 10 years. They were randomly divided in to two groups, Group A and Group B.
Group A: (Control group) Received 0.25% Bupivacaine.

Group B: (Study group) received 0.25% Bupivacaine + 1μg/kg Dexmedetomidine.
Total volume for caudal block being 1 ml/kg in both groups, with maximum of drug volume of 20 cc.8The study was approved by Institutional Ethical Committee.
Selection of Cases: All the patients underwent thorough pre-anaesthesia assessment including detailed case history, clinical examination and routine laboratory investigations.
Inclusion Criteria
• ASA status I and II.
• Age group of 2-10 years.
• Patients coming for routine infraumbilical surgeries. 

Exclusion Criteria
• ASA grade III and IV
• Infection at the site of injection
• Coagulopathy or anticoagulation.
• Congenital abnormalities of lower spine and meninges.
• Active disease of the CNS.
• History of allergy to local anaesthetics.
• Refusal of consent by parents. 

Technique of Caudal Block
After gaining an IV access, all the monitors were applied. Patients were premedicated with inj. Midazolam 0.03 mg/kg, inj. Glycopyrrolate 0.04 mg/kg and inj. Ketamine 1 mg/kg i.v. 100% oxygenation was maintained by face mask with spontaneous ventilation on Jackson Rees modification of Ayer’s T- piece. Lateral position was given with head in extended position. Painting and drapping was done under all aseptic precautions. Sacral hiatus was palpated and cornua of sacrum was identified. Surface anaesthesia was given at sacral hiatus with inj. Lignocaine 2% 1cc. A 21G hypodermic needle was introduced at an angle of about 45° to the skin, aiming to penetrate the posterior sacrococcygeal ligament and to enter the sacral canal. Drug doses used were 1ml/kg, according to Armitage formula8 with maximum drug volume 20 cc. The total amount of drug was injected over 60 to 90 seconds. After completion of caudal block, patient was made supine with slight head up position. Patients was handed over to surgeons 20 min after performance of block. Inj Midazolam 0.03 mg/kg was supplemented whenever child would wake up. The total number of midazolam supplementations were noted. Inj. Ketamine 1 mg/kg was given whenever child moved lower limb. These cases were considered failure of caudal block and were not included in study. Haemodynamic parameters in the form of pulse rate, blood pressure, SpO2, respiratory rate were observed. Pain relief was assessed by Paediatric Objective Pain Scale at interval of every 2 hrs till patent complaint of pain. Duration of analgesia was noted as the time from injection of drug to first complaint of pain by patient or cry. Ambulation time was noted as the time after which patient started walking. Complications if any were noted.

RESULTS
The mean age of the patients in Group A was 3.8 ±1.46 years and in Group B was 3.2 ±1.37 years (p=0.10). The males were more common in both the groups with a ratio of 6.5:1 in Group A and 5:1 in Group B. Both the groups were comparable as there was no statistical significant difference between two groups with respect to age, sex and weight. Most of the patients underwent herniotomy (Group A=21; Group B=12), circumcision (group A=5; Group B=12) and orchidopexy (Group A=4; Group B=1). The average duration of analgesia for group A and B was 5.86 ±1.21 Hrs and 9.26 ± 1.48 Hrs respectively(p < 0.05), indicating that duration of analgesia was more in group B than group A. There was no significant change in pulse rate from baseline in any of the groups. The difference between both the groups is statistically insignificant. None of the patients from any of the group had significant bradycardia, so no patient required chronotropic support for bradycardia. There was fall in Mean Arterial Pressure in both the groups. Fall in Mean Arterial Pressure was more in group B than in Group A. The difference between both the groups is statistically significant. However, none of the patients required ionotropic support for hypotension from any of the groups. There was no statistical significance between two groups for average values for intra-operative oxygen saturation and the average intraoperative respiratory rate.

Table 1: Postoperative Change in Pulse Rate (%) in Recovery Room

All patients were shifted in the recovery room approximately 1 hour after the block and were monitored in the recovery room for 2 hours. Baseline values of preoperative hemodynamic parameters were taken for comparison with postoperative values. Above table shows the average pulse rate in recovery room in both the groups. There is no statistical difference between both the groups.

 

Table 2: Change in Mean Arterial Pressure Postoperatively

Above chart shows the change in mean arterial pressure in recovery room for both the groups. There was no statistical difference between both the groups.

 

Table 3: Postoperative Changes in Spo2 (%) in Recovery Room

There was no statistically significant difference in average value for SpO2 in the recovery room between the two groups.

Table 4: Postoperative Changes in Respiratory Rate in Recovery Room

Above table shows the average respiratory rate in recovery room of both the groups. No statistical difference is found between both the groups.

 

Table 5: Postoperative Complications                                      

Two patients from group A and 1 patient from group B had vomiting. While 2 patients from both group A and group B complained of failure to pass urine at 6 hrs. There was no statistical difference between the two groups.

DISCUSSION
This study was conducted to see the effect of dexmedetomidine when used along with bupivacaine for caudal block, regarding hemodynamic stability and complications if any. There was no significant change in pulse rate from baseline in any of the groups intraoperatively and postoperatively. The difference between both the groups was statistically insignificant. There was fall in Mean Arterial Pressure in both the groups. Fall in Mean Arterial Pressure was more in group B than in Group A. The difference between both the groups was statistically significant. Similar findings were obtained in a study conducted by Schnaider et al.9 However, none of the patients required ionotropic support for hypotension from any of the groups. Similar haemodynamic stability was seen in previous study by Hingson RA.10 Hypotension is a rare complication in infants and children less than seven years of age. Even after high thoracic blockade with local anaesthetics, cardiovascular stability is believed to depend on the immaturity of the sympathetic nervous system, whereas the parasympathetic nervous system seems to be completely differenciated.11-13 Futhermore, compared with their total blood volume, the amount of pooled blood in the lower extremities is proportionally smaller in children than of adults.14 This may be the reason that fall in blood pressure was not up to the extent so that ionotropic support was required. No fall in oxygen saturation was noted in any of the groups intraoperatively and postoperatively. There is no statistically significant difference in the respiratory rate in both the groups. Spontaneous ventilation was well preserved in every patient. No respiratory depression was noted in recovery room either. The hemodynamic stability and absence of respiratory side effects in patients receiving dexmedetomidine is supported by the studies conducted by Koroglu et al15 and Tobias JD.16 Two patients from group A and one patient from group B had vomiting in the postoperative period. While two patients from both group A and group B complained of failure to pass urine at 6 hrs. The difference between both the groups is statistically insignificant. In conclusion, all the patients were haemdynamically stable and did not required any ionotropic support. All the patients were calm, quiet and easily arousable. No respiratory depression was noted in any of the patients receiving dexmedetomidine. Thus, the addition of dexmedetomidine in the dose of 1μg/kg to 0.25% bupivacaine for caudal blockade significantly prolongs the duration of analgesia without any significant hemodynamic changes and is safe for use in paediatric patients.

 

REFERENCES
1. Markakis DA. Regional anaesthesia in paediatrics. Anesthesiol Clin North America 2000; 18(2):355-9. 

2. Broadman LM, Hannullah RS, Norden JM, et al. “Kiddie Caudal” experience with 1154 consecutive cases without complicated abstracted. Anaesth. Analg 1987; 66:518. 

3. Samuel M, Hampson-Evans D, Cunnington P. Prospective to arandomized double-blind controlled trial to assess efficacy of double caudal analgesia in hypospadias repair. J Pediatr Surg 2002; 37:168– 174.
4. De-Beer DAH, Thomas ML. Caudal additives in children – solutions or problems? Br J Anaesth 2003; 90(4):487-98. 

5. Cook B, Doyle E. The use of additives to local anaesthetic solutions for caudal epidural blockade. Paediatric Anaesth 1996; 6:353-9.
6. Constant I, Gall O, Gouyet L et al. Addition of clonidine or fentanyl to local anaesthetics prolongs the duration of surgical analgesia after single shot caudal block in children. Br J Anaesth 1998; 80:294–298.
7. Grewal A. Dexmedetomidine: new avenues. J Anaesthesiol Clin Pharmacol 2011; 27:3. 

8. Armitage EN. Caudal block in children. Anaesthesia 1979; 34:396.
9. Schnaider TB, Vieira AM, Brandao ACA, Lobo MVT. Intraoperative analgesic effect of epidural ketamine, clonidine or dexmedetomidine for upper abdominal surgery. Rev Bras Anesthesiol 2005; 55:525–31.
10. Hingson RA. The pathway across half a century of development of safe control of obstetric pain in childbirth. Reg Anesth 1981; 6:62–66.
11. Assali NS, Brinkman CR, Woods JR Jr, et al. Development of neurohumoral control of fetal, neonatal, and adult cardiovascular functions. Am J Obstet Gynecol 1977; 129:748-59.
12. Buckley NM, Brazeau P, Gootman PM. Maturation of circulatory responses to adrenergic stimuli. Fed Proc 1983; 42:1643-7.
13. Dohi S, Seino H. Spinal anesthesia in premature infants: dosage and effects of sympathectomy [letter]. Anesthesiology 1986; 65:559-61.
14. Arthur DS, McNicol LR. Local anaesthetic techniques in paediatric surgery. Br J Anaesth 1986; 58:760-78.
15. Koroglu A, Demirbilek S, Teksan H, Sagir O, But AK, Ersoy MO. Sedative, haemodynamic and respiratory effects of dexmedetomidine in children undergoing magnetic resonance imaging examination: Preliminary results. Br J Anaesth 2005; 94:821-4.
16. Tobias JD. Dexmedetomidine: Applications in pediatric critical care and pediatric anesthesiology. Pediatr Crit Care Med. 2007; 8:115–31.