Comparative Study of block characteristics with  Dexmedetomidine vsFentanyl as Adjuvants to Intrathecal Bupivacaine for Cesarean Section: A Randomized, Double-Blind Clinical Trial” 

INTRODUCTION

Spinal anesthesia (SA) is the preferred technique for parturients undergoing lower segment cesarean section (LSCS). The practice of adding adjuvants to local anesthetic agents in SA aims to enhance the onset speed and duration of analgesia. These adjuvants also help mitigate the dose-dependent adverse effects of local anesthetics through synergistic effects.

Opioids are commonly used as adjuvants to spinal local anesthetics to provide a shorter onset time and increased intensity and duration of the sensory and motor block, with minimal sympathetic block.

Dexmedetomidine, a relatively new and highly selective alpha-2 adrenoceptor agonist, produces analgesic and sedative effects. It has been used as an adjuvant in SA, resulting in a prolonged duration of block and improved postoperative analgesia without associated hypotension or other adverse events.

 Recent comparisons of low doses of bupivacaine with dexmedetomidine and fentanyl in parturients have concluded that dexmedetomidine provides better analgesia without significantly affecting neonatal APGAR scores compared to fentanyl.

More importantly, this drug does not cross the placenta significantly (0.77 maternal/fetal index), which confirmed its safety in cesarean delivery.Many reports have indicated that intrathecal administration of Dexmedetomidine can prolong analgesia and reduce the side effects associated with the administration of opioids.

AIMS &OBJECTIVES

AIM

To compare the block characteristics of spinal anaesthesia with 10 mg of 0.5% bupivacaine hyperbaric with dexmedetomidine 5 mcg vs fentanyl 25 mcg as adjuvants for elective lower segment cesarean section (LSCS).

OBJECTIVES

Primary objective:

To compare the duration of sensory blockade.

Secondary objective : 

 To compare the onset and duration of motor block 

To assess post operative pain using Visual Analogue Score(VAS). Side effects if any.

To assess and compare the haemodynamic parameters between both groups.

Apgar scores of the neonate at birth and after 5minutes.

REVIEW OF LITERATURE

JUSTIFICATION

Only very few studies have been done comparing the effects of dexmedetomedicine  and fentanyl as an adjuvant to bupivaine intrathecally in patients undergoing elective caesarean section.

STUDY DESIGN: 

A prospective randomized double-blind study.  

SAMPLE SIZE: 

Sample size is calculated using the formula for difference in means with alpha error of 5% and power 80% using data from Li et al *.. With the SD in group 1 is 46.3 And SD in group 2 is 25.72 .with the mean difference of 26.2(effect size :0.7275):alpha error of 5% and the required sample per group was estimated to be 35 in each group.

*Li, X., Li, Y., Lv, X., Wang, X., & Liu, S. (2020). The efficacy and safety of intrathecal dexmedetomidine for parturients undergoing cesarean section: a double-blind randomized controlled trial. BMC Anesthesiology, 20(1). https://doi.org/10.1186/s12871-020-01109-4

MATERIALS AND METHODS

Inclusion criteria –

ASA Il patients

Age: 20-40 years

Weight: >50 kgs

Term pregnant women planned for caesarean section

Living fetus

Intact amniotic membranes

No history of bleeding tendency

Exclusion criteria –

Patient refusal.

Patients having known hypersensitivity to the drugs.

 Age: <20 or >40 years

ASA Ill or more.

Weight: <50 kgs 

Contraindication to spinal anaesthesia (coagulopathy, significant hypovolemia, systemic or local sepsis, increased intracranial pressure, local anesthetic or bupivacaine allergy).

High risk pregnancies as preeclampsia, any medical disorder ( cardiac disease ).

Chronic pain or daily intake of analgesic.

 Abnormal placenta station e.g. placenta previa.

METHODOLODY

After obtaining approval from the institutional ethics committee and CTRI registration, written and informed patient consent is abtained from the patients fullfiling the eligibility criteria, the study will be conducted on 35 patients on each group under ASA physical status 2  scheduled for elective LSCS at the Department of Anaesthesiology, Chettinad Hospital and Research Institute, Kelambakkam, Chennai during the Year 2023-2024. The enrolled subjects will be randomized into the 2 study groups using computer generated randomization code.

Computer generated randomisation will be used for group allocation.The randomization sequence will be generated by a statistician and handed over in sealed opaque sequentially numbered envelopes. The opaque cover will be opened by an anesthesia resident not involved in the study and prepared the LAs or LA mixtures as per the allocation card.

Patients in each group will receive anaesthesia as follows:

Group A  (n= 35) Patients will receive hyperbaric 0.5% bupivacaine 10 mg with Dexmedetomidine 5mcg diluted with NS.

Group B  (n= 35) Patients will receive hyperbaric 0.5% bupivacaine 10 mg with 25 mcg fentanyl 

All the patients will receive Tab Perinorm10mg HS and 6am in the morning of surgery.

On arrival in Pre-op area an IV access with 18G IV cannula will be secured and RL will be started.

Establishment of proper standard monitoring systems (pulse oximetry, continuous electrocardiography and non-invasive blood pressure monitoring and SpO2).  

Sitting position is recommended for all patients included in this study. Under all aseptic precautions L3-L4 inter-space will be infiltrated with 2ml of 2% Inj. Lignocaine.

Study drug will be prepared by the person not involved in the study. The subarachnoid space will be entered at L3-L4 intervertebral-space via the midline approach using 26-Gauge Quincke spinal needle. The correct needle placement will be identified by free flow of cerebrospinal fluid and study drug will be injected by the anesthesiologist.

Patients in each group will receive anaesthesia as follows:

Group A  (n= 35) Patients will receive hyperbaric 0.5% bupivacaine 10 mg with Dexmedetomidine 5mcg (0.5ml) diluted with NS

Group B  (n= 35) Patients will receive hyperbaric 0.5% bupivacaine 10 mg with 25 mcg fentanyl 

The patient will be placed in supine position to carry over the initial assessment. The onset of sensory and motor blockade will be assessed at baseline and 3 min interval up to 15 min.

The onset of sensory blockade will be considered as loss of cold sensations at T10 level and the highest level of sensory blockade will  also be noted. The sensory block level was tested by the pinprick method using a blunt 25-G needle.Assessment of the dermatomal level was done every 1 min until the peak sensory block level was achieved Subsequently frequent testing every 10 min was performed until regression to S1 dermatome.

The onset of motor blockade will be evaluated using Modified Bromage score 2.

The duration of sensory blockade is defined as the time taken from intrathecal injection to sensory regression to S1 dermatome.

The duration of sensory blockade is monitored for every 15 min until regression to dermatome s1 and thereafter moitored for every 30 min. 

Continuous Vital monitoring includes patient’s HR, NIBP, RR and SPO2 will be monitored at 3 min interval up to 15 minutes then every 5 minutes till end of the procedure. 

Throughout the procedure, patient will receive 6 liters of oxygen per minute through facemask.

POST- OPERATIVE PAIN AND SIDE EFFECTS

Post-surgery, the time for request of first rescue analgesia will be noted from the time of administration of spinal anaesthesia to complain of pain VAS score of >/=5 (i.e. 0=No Pain, 10=worst imaginable pain).

In case of Pain/ Shivering,Inj.Paracetamol 1g I.V will be given followed by Inj. Tramadol 50 mg will be given intravenously. 

Side effects such as nausea and vomiting will be treated using Inj. Ondensetron 4mg IV, Bradycardia by Inj. Atropine 0.6mg and Hypotension by adequate fluids or if required Inj. Epherdrine 6mcg.

PROFORMA:

“Comparative Study of  Dexmedetomidine vs

Fentanyl as Adjuvants to Intrathecal Bupivacaine in Cesarean Section: A Randomized, Double-Blind Clinical Trial” 

Patients Name: Age/Sex:

Weight: Hospital IP No:

Diagnosis: Procedure:

Date of Surgery: ASA Grade:

Elective/Emergency:

Duration of surgery :

Table 1: Sensory and Motor blockade Characteristics