The aim of the study is to investigate the analgesic effects of the subcutaneous wound infiltration with tramadol, ketamine, dexamethasone, dexmedetomidine and midazolam as adjuvant to ropivacaine, compared to ropivacaine alone in patients undergoing Video-Assisted thoracoscopic Surgery (VATS) procedures.

After obtaining approval from Ethical Review Committee (ERC) of Aga Khan University Hospital Karachi (AKUH), and inform about the study to primary surgeon, informed written consent will be obtained from the patients fulfilling the inclusion criteria.

Patients will be recruit in the study during the preoperative anesthesia evaluation either at the preoperative clinic or from the ward after admission. Their Medical Record (MR) number will be send to the Clinical Trials Unit (CTU), along with their expect date, day and timing of surgery. The CTU will randomly allocate the patients to one of the six groups, based on computer generated allocation. After the patient will reach the preoperative area in the operating room (OR), an email request will be generated to the CTU who will release the prepared study drug syringe and will send it to the Principal Investigator (PI). The syringe contain either Ropivacaine alone or in combinations with other adjuvants. The drugs for all six groups looks alike, so that the patient, principal investigator, and surgeon administering the drugs or making observations will all blinded.

Group A: Patients will receive subcutaneous wound infiltration with 24ml of 0.25% Ropivacaine in three divided doses (i.e. 8 mL per incision) (control group). Total dose of Ropivacaine will be 60 mg.

Group B: Patients will receive subcutaneous wound infiltration with total volume of 24 mL of 0.25% ropivacaine + 1mg/kg ketamine (8 mL per incision) (ketamine group).

Group C: Patients will receive subcutaneous wound infiltration with total volume of 24 mL of 0.25% ropivacaine + 2mg/kg tramadol (8 mL per incision) (Tramadol group).

Group D: Patients will receive subcutaneous wound infiltration with total volume of 24 mL of 0.25% ropivacaine + 50 μg/kg midazolam (8 mL per incision) (Midazolam group).

Group E: Patients will receive subcutaneous wound infiltration with total volume of 24 mL of 0.25% ropivacaine+ 8mg dexamethasone (8 mL per incision) (Dexamethasone group).

Group F: Patients will receive subcutaneous wound infiltration with total volume of 24 mL of 0.25% Ropivacaine + 0.5μg/kg dexmedetomidine (8mL per incision) (Dexmedetomidine group).

All patient will be given general anesthesia as per standard of care. Subjects will be blinded to the identity of the study drug they receive for postoperative analgesia. The study drugs will be prepared by an anaesthesiologist unrelated to the study and will be infiltrated by the surgeon intraoperatively before skin closure.

Pre-operatively, patients will be taught how to evaluate pain intensity using the visual analogue scale (VAS) scored from 0 to 10 (where 0 = no pain and 10 = worst pain).On arrival to the operative room, routine monitoring including ECG, non-invasive blood pressure, pulse oximetry and capnography was applied. All patient will be pre-medicated with tablet midazolam 7.5mg PO before surgery.

In all patients, general anaesthesia will be induce with intravenous morphine (0.1mg/kg) and 2 mg/kg propofol; endotracheal intubation will be facilitated with 0.5 mg/kg atracurium. Anaesthesia will be maintain with inhalational anaesthetic (MAC 1.2 -1.4%) isoflurane in 50% oxygen/air mixture and 0.03 mg/kg atracurium bolus given every 30 min. Intraoperatively, intravenous paracetamol (15mg/kg) will be given to all patients. In Video assisted thoracotomy surgery (VATS), three incision lines are used for port insertion. Surgeries which involves less than 3 ports will be excluded. Just before skin closure, surgeon will infiltrate the prepared study drug (groups will be randomly allocated preoperatively), 8 ml per incision site. Prophylactic antiemetic (Ondansetron 4 mg) will be given intraoperatively.

Postoperatively, all patients will admit to postanaesthesia care unit (PACU); the patients' heart rate, non-invasive blood pressure, respiratory rate and oxygen saturation will be monitor and record. The presence and severity of pain at rest(VAS-R) and on coughing (VAS-M) will be assess by using VAS score, and sedation will be assess by using sedation score as (awake and alert = 0, quietly awake = 1, asleep but easily aroused = 2, deeply asleep = 3) at the following time points: at 0, 2, 6, 12 and 24 h postoperatively. The time to first request for rescue analgesia will be recorded Patients will be given tramadol 50mg intravenously (as per need) upon request for initial rescue analgesia (if VAS score >4), which then will be given on regular doses (tramadol 50 mg IV every 8 hourly along with paracetamol 1 gm IV every 6 hourly).

Adverse effects:

Adverse Events are defined as 'Any untoward medical occurrence in a trial patient to whom a research treatment or procedure has been administered, including occurrences which are not necessarily caused by or related to that treatment or procedure.

Post-operative assessment of other effects patients will be observed any of the following till 2 hours to discharge of the patient from PACU.

• Hallucination is a sensory perception experienced in the absence of an external stimulus as distinct from an illusion which is a misperception of an external stimulus.
• Nystagmus is rapid involuntary rhythmic eye movement, with the eyes moving quickly in one direction (quick phase), and then slowly in the other (slow phase).
• Nausea is the sensation of unease and discomfort in the stomach with an urge to vomit.
• Sedation is define as, reduction of anxiety, stress, irritability, or excitement
• Respiratory depression (Respiratory rate less than 8/min)
• Hypo and hypertension (Systolic blood pressure <90 mm Hg or > 140 mm Hg)

Management of side effects:

• If hallucination or nystagmus happens, then it will be manage by giving intravenous haloperidol 5mg and observe the patient.
• If patient complains of nausea, it will be manage by giving intravenous injection metoclopramide 10mg
• If respiratory depression happens, then it will be manage by titrating the amount of injection naloxone 0.1mg intravenously and monitor the patient.
• If hypotension happen, then it will be manage by giving intravenous fluid and see the response, if hypotension persists then investigator will give injection ephedrine or phenylephrine in titrating dose.
• If hypertension occurs, it will be manage by giving intravenous hydralazine or metoprolol in titrating dose.

Serious Adverse Events:

• Serious Adverse Events are defined as an untoward event that: Results in death; Is life-threatening*; Requires hospitalization** or prolongation of existing hospitalization; Results in persistent or significant disability or incapacity; Or, is otherwise considered medically significant by the Investigator (18)
• *The term "life-threatening" refers to an event in which the patient was at risk of death at the time of the event; it does not refer to an event which hypothetically might have caused death if it were more severe. ** Patients must be formally admitted - waiting in out-patients or A&E does not constitute an SAE (even though this can sometimes be overnight). Similarly, planned hospitalizations that clearly are not related to the condition under investigation or hospitalizations/prolongation of hospitalization due to social reasons should not be considered as serious adverse event (18).

There is no direct financial or other benefit for the participant of the study. However, these medicines will be provided free. In case of any event related to the study drug, it will be managed & cost will be borne by the institution.

Inclusion Criteria:

1. ASA I to III.
2. Age >18 years.
3. Either sex.
4. Elective Video assisted thoracotomy surgery (VATS) under general anaesthesia

Exclusion Criteria:

1. ASA IV & V.
2. Coagulation disorders.
3. Infection at the vicinity of the surgical wound.
4. Raised intracranial pressure.
5. History of hypersensitivity or known allergy to any study drug.
6. History of opioid addiction.
7. History of seizure disorder.
8. Those who are not willing to participate in the study.
9. Allergy to local anesthetics.
10. Duration of surgery greater than 2 hours.