Effect of Intranasal Dexmedetomidine on Surgical Field and Haemodynamics in Endoscopic Transnasal Transphenoidal Pituitary Surgery: a Comparison of Two Doses

Brief description of the proposal

Effect of intranasal Dexmedetomidine on surgical field and hemodynamics in endoscopic transnasal transphenoidal pituitary surgery: a comparison of two doses

Introduction:

Transnasal transsphenoidal (TNTS) approach for pituitary surgery is well established and preferred route offering various advantages like minimally invasive approach, expedited recovery process and better patient compliance.[1,2] Nasal preparation plays an important role in improvement of surgical field and ease of endoscopic procedure for which vasoconstrictors like adrenaline have been conventionally used.  However its systemic absorption presents with myriad problems like tachycardia and hypertension which elevates risk of bleeding.[3] To counteract these challenges additional doses of anaesthetic drugs are required which may lead to delayed emergence.[4,5] Dexmedetomidine is a selective alpha-2 agonist which has sedative, analgesic and anxiolytic properties.[6,7] It has demonstrated opioid sparing effects sympatholytic properties which can produce stable hemodynamics perioperatively.[8,9] intranasal dexmedetomidine is an effective, non-invasive method of achieving effective sedation and analgesia in various surgeries.[10,11] Effects of single dose of nebulised dexmedetomidine has been previously studied in TNTS surgeries.[12] We aim to study the effects of intranasal dexmedotomidine on surgical field quality, hemodynamic effects intraoperatively comparing two doses in patients undergoing TNTS endoscopic surgery for pituitary tumours.

Aim:

To evaluate and compare the effects of dexmedetomidine 1 mcg/kg versus 2 mcg/kg for preoperative nasal passage preparation on surgical field visualisation and intraoperative hemodynamic parameters in patients undergoing TNTS surgery for pituitary adenoma.

Objectives:

Primary outcomes

1. To evaluate the quality of endoscopic surgical field visualisation and amount of bleeding during nasal mucosal flap resection.
2. To evaluate the effects on intraoperative hemodynamic profile

Secondary outcomes

3. To assess requirement of additional anaesthetic agents
4. To assess the quality of emergence post surgery

Justification:

Intranasal preparation with dexmedetomidine may provide better surgical field quality and help attenuate hemodynamic stress response to surgery

Methodology:

Design of study:

This will be a prospective randomised double blinded comparative study

Study duration:

From 15th July 2025 to 30th July 2026

Sample size:

The sample size was determined based on the available literature, specifically regarding Formmer’s score from a prior study. In this study, the proportion of outcomes with Formmer’s scores >3 in the control group was 53%, whereas in the treatment group, it was 16%.[13] To detect this difference in outcomes with a significance level of 5% and a power of 80%, a sample size of 25 patients per group was calculated. Consequently, the total sample size for our study will be 75 patients.

Selection of cases:

After obtaining approval from Institutional Ethics Committee, this study will be conducted at Superspeciality hospital, NSCB Medical college Jabalpur.

Inclusion criteria:

1. Adult patients 18-60 years presenting with pituitary tumours
2. ASA class I & II
3. GCS 15

Exclusion criteria:

1. Patient refusal

2. GCS < 15

3. Raised ICP

4. Previous nasal surgery

5. Pregnancy and ongoing lactation

6. Pituitary apoplexy

7. Cardiac comorbidities associated with pituitary tumours

8.   Allergy to any of the study drugs

Method of study:

This study will be conducted at Superspeciality hospital, NSCB Medical college, Jabalpur, after approval from our institutional Ethical committee and Review board. This prospective, randomised, double blind study will enrol  60 patients of American Society of Anesthesiologists grade I & II, fulfilling the inclusion criteria undergoing endoscopic TNTS surgery for pituitary tumours, after written and informed consent. They will be randomly divided in three groups of 25 each

Group D1 (n=25): Dexmedetomidine 1mcg/kg with saline 10ml solution

Group D2 (n=25): Dexmedetomidine 2mcg/kg with saline 10 ml solution

Group C (n=25):  Saline of equal volume

In the operation theatre large bore IV access will be established and 0.9% normal saline will be started. 5 lead ECG, NIBP, SpO2, ETCO2, monitoring will be established. Invasive arterial line and urine catheter will be placed after induction.

Anaesthesia protocol:

Anaesthesia will be induced with intravenous midazolam 0.03 mg/kg, fentanyl 2 mcg/kg, propofol 2mg/kg, vecuronium 0.1 mg/kg. Appropriate sized endotracheal tube will be secured and throat pack will be inserted. Anaesthesia will be maintained with 50% oxygen in air mixture with constant gas flow within a narrow end tidal concentration range of sevoflurane.

After patient positioning and head fixation with Mayfield 3 pins clamp, bilateral nasal cavity will be cleaned with betadine solution. According to the group allocation the calculated dexmedetomidine dose will be mixed with saline to a total volume of 10 ml and six cotton strips will be soaked with the solution. After nasal decontamination, surgeon will insert three cotton strips in each nasal cavity. One placed on the floor of the nasal cavity, second strip placed over the area covering middle meatus and third one will be placed to cover the frontal recess. The cotton packs will be left in situ for 10 minutes.

After removal of dexmedetomidine packs, adrenaline (1:100,000) packs will be inserted and left in situ for 10 minutes. All the surgeries will be done by the same neurosurgical team. At the end of surgery ondansetron 0.1 mg/kg and paracetamol 15mg/kg will be administered. After final nasal packing, sevoflurane will be discontinued. Mayfield pins will be removed, careful oral suction under direct vision will be carried out. Patients will be extubated after reversal and fulfilment of extubation criteria. Post operatively patients will be monitored in intensive care unit for 24 hours.

Study protocol:

Hemodynamic parameters which will include heart rate, systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial pressure (MAP) will be measured at various points. T0, baseline; T1, post induction; T2, post dexmedetomidine nasal packing; T3, post adrenaline packing; T4, pre scope insertion; T5, after scope insertion; T6, during mucosal resection; T7, during sphenoid drilling; T8, during tumour resection; T9, after stopping anesthesia; T10, after extubation.

Surgical field quality will be assessed using Formmers score (1, mild bleeding without any surgical nuisance; 2, moderate bleeding without any interference to surgery; 3, moderate bleeding that moderately compromised surgical field; 4, bleeding heavy but controllable significantly interfering with surgery; 5, massive uncontrollable bleeding). Time taken for emergence and extubation will also be noted.

In the event of HR or MAP increasing >20% of baseline, fentanyl 0.5 mcg/kg bolus will be administered. In the event of persistent elevation, labetalol 5mg/bolus and propofol 30 mg/bolus will be given. If MAP decreases to  <20% mephentermine 3mg/bolus will be administered. Any reduction in HR <40 bpm, glycopyrrolate 10 mcg/kg will be given.

All complications and drugs given at various time points will be noted.

Statistical analysis:

Data will be collected using GraphPad Prism version 10.4.2 (633) for windows software. Mean, standard deviation (SD) and confidence intervals (CI) will be calculated in the three groups for measurable demographic data like age and weight. Inter-group and intra-group hemodynamic parameters at different time points will be assessed with repeated measure ANOVA (analysis of variance) test. Categorical data will be assessed with chi-square test.

Results and Conclusion:

Results and conclusions will be drawn at the end of study.