Ultrasound-Guided Erector Spinae Plane Block Versus Intravenous Nalbuphine for Postoperative Analgesia After Video-assisted Thoracoscopy in Obese Patients: A Randomized Controlled Trial of Safety and Effectiveness
Phase: PHASE4
Conditions: Postoperative Pain Management
Sponsor: Zagazig University

Zagazig University 
Faculty of Medicine 
Anethesia, Intensive Care And Pain Management Department 
 
 
Ultrasound-Guided Erector Spinae Plane Block versus 
Intravenous Nalbuphine for Postoperative Analgesia after 
video-assisted thoracoscopy in obese patients: A randomized 
controlled trial of safety and effectiveness 
 
protocol of a study performed by 
BY 
Ahmed Beniamen Mohamed Hussien 
(MD) 
Essamedin mamdoh negm 
(MD) 
 
 
 
 
Faculty of Medicine 
Zagazig University 
from 8-7-2025 to 7-1-2026 
the study was approved from the research ethical committee at the 
Faculty of Medicine, Zagazig University (IRB#5386/ 8-7-2025). 
Faculty of Medicine 
Zagazig University 
 
 
 

Introduction 
The prevention of respiratory complications is a significant issue 
after thoracic surgery and requires adequate postoperative pain 
management. Prevention and management of surgery-related pain is 
essential in VATS, due to high incidence of moderate to severe acute 
postoperative pain. Apart from non-steroid anti-inflammatory agents and 
intravenous opioids, local anesthetic infiltration of incision sites, 
preemptive analgesia methods, and regional anesthesia techniques play 
a role in multimodal analgesia [1,2]. 
Guidelines for enhanced recovery after lung surgery recommend 
the use of regional analgesia and opioid-sparing analgesia to facilitate 
early mobilization and reduce the risk of pulmonary complications [4]. 
 Thoracic epidural analgesia (TEA) is recognized as the gold 
standard for acute postoperative pain relief after thoracotomy, multiple 
authors have suggested it is too invasive for VATS [5]. 
The Paravertebral Block (PVB) is a widely utilized regional 
anesthesia technique for video-assisted thoracoscopic surgery (VATS). 
However, it is still regarded as an invasive procedure, raising concerns 
about its benefit-risk balance. As a neuraxial technique, it carries certain 
risks, including the potential for spinal hematoma and epidural abscess 
[6,7]. 
In recent years, innovative chest wall blocks like the Erector 
Spinae Plane Block (ESPB) have been introduced to enhance pain relief 
while minimizing the risk of damaging nearby vital structures. The 
ultrasound landmarks for the ESPB are easier to locate and situated 
farther from the neuraxis and pleura compared to the epidural and 
paravertebral spaces. This characteristic makes it a potentially less 
invasive option and offers a simpler and safer alternative for pain 
management after video-assisted thoracoscopic surgery (VATS). 
Originally described for managing thoracic neuropathic pain, the ESPB 
has emerged as an effective regional anesthesia technique for preventing 
postoperative pain in VATS [3]. 
 In ESPB, a local anesthetic is reported to be administered at the 
level of T6 into the inter-fascial plane between the transverse process of 
the vertebra and the erector spinae muscles, widely spread cranially and 
caudally to provide anesthesia from T3 to T9 over the ipsilateral 
hemithorax. Studies have reported that ESPB affects both the ventral and 
dorsal rami and leading to blockage of both visceral and somatic pain 
[3]. 
2. Patients and methods 
2.1. Study population and setting: 
This prospective, randomized, controlled clinical trial will be 
conducted at the thoracic surgery operation room, cardiothoracic surgery 

building, Zagazig University Hospitals, from July 2025 to December 
2025. 
Our study included 102 patients who are planned for video-
assisted thoracoscopy. Cases will randomly divided into two groups: 
Erector Spinae Plane Block (ESPB) and the control group, comprising 
51 patients each. Inclusion criteria also include: American Society of 
Anesthesiologist (ASA) status of II and III, age between 21 years and 60 
years, and BMI (body mass index) between 30 and 40 kg/ m2. Patients 
who will be excluded from the present study included: BMI <30 or > 40 
kg/ m2, chronic pain with regular use of either opioids or gabapentinoids 
during the 2 weeks before surgery, history of thoracic surgery on the 
same side, anticipated high risk of conversion to thoracotomy, taking 
anticoagulation, suffering from any bleeding disorders, known allergy to 
local anesthetics, nalbuphine or fentanyl, active infection at the injection 
site, 
pre-existing 
neurological 
or 
psychiatric 
illness, 
severe 
cardiovascular disease, liver failure, renal failure (estimated glomerular 
filtration rate less than 15 ml min), and pregnancy. 
Patients will be also excluded after randomization if they have 
converted to thoracotomy, severe intra- or postoperative blood loss 
>1000cc, required postoperative mechanical ventilation, or a technical 
difficulty in the ESPB performance. 
2.2. Randomization and allocation 
Patients will be randomized in a one-to-one ratio and assigned to 
either the ESPB (group A) or control group (group B) (Fig. 1). 
Randomization allocations will be kept in sealed opaque covers and only 
opened by the investigator immediately prior to the ESPB, which will be 
performed in a holding area before entry into the block rooms. All blocks 
will be performed by the same anesthetist using the linear probe of an 
Ultrasound machine (GE Vivid E95).  
 
2.3. Preparation of patients  
Prior to surgery, patients will be instructed to fast for eight hours. 
Standard non-invasive monitoring was started once patients entered the 
block room. Intravenous access will be then obtained, and 2mg of 
midazolam will be given as sedation to all patients. 
 
2.4. Monitoring: 
• Standard monitoring will be applied and maintained throughout 
the procedure, including 5-lead electrocardiogram, non-invasive 
blood pressure, pulse oximetry, end-tidal carbon dioxide. 
• Hemodynamic parameters: Heart rate (HR) and the mean arterial 
blood pressure (MAP) will be recorded preoperatively (baseline 
data) and intraoperatively every 5 minutes for 15 minutes, then 

every 15 minutes afterward till the end of surgery. 
2.5. Standardized perioperative protocol (for both groups): 
• Intravenous induction drugs include: fentanyl 2 microgram per 
kilogram, propofol 2 mg /kg, and cisatracurium 0.15mg /kg 
according to Lean Body Weight (LBW). 
• Intubation and mechanical ventilation will be constituted to all 
patients using volume-controlled positive-pressure ventilation 
with a tidal volume of 4–6 ml/kg of ideal body weight (IBW) 
to maintain end-tidal carbon dioxide tension at 35–45 mm Hg. 
• The lung isolation technique will be standardized for all 
patients with a left double-lumen endotracheal tube. The 
adequate position of the double-lumen tube was confirmed by 
fiberoptic bronchoscopy after intubation and in the lateral 
decubitus position. The IV fluid administration was limited to 
6 mL/kg/h of crystalloids. 
• Anesthesia was maintained with100% oxygen and 2% 
sevoflurane and propofol infusion as needed. 
• Additional doses of cisatracurium (0.04 mg /kg) will be given 
every 20 minutes. 
• Fentanyl doses of 25 mcg will be administered intravenously 
for any intraoperative increase in heart rate (HR) or mean 
arterial pressure (MAP) above 20% of baseline. 
• At the beginning of the procedure, each patient will receive 
standard regimen for prevention of postoperative nausea and 
vomiting (PONV) comprising dexamethasone 4 mg IV and 
ondansetron 8 mg IV. 
• Recovery from general anesthesia: At the end of the operation 
(Closure of the wound), sevoflurane will be discontinued, 
residual neuromuscular blockade will be reversed using 
neostigmine 
(0.05mg/kg) 
and 
atropine 
(0.02mg/kg) 
administered intravenously, and the patient will be extubated. 
• After full recovery, when the verbal Numerical Rating Scale 
(VNRS) is ≥ 3, a rescue drug in the form of nalbuphine titration 
5 mg intravenously will be given with a maximum dose of 60 
mg per day. 
2.6. Multimodal opioid-sparing analgesia technique will be performed only in 
group A and includes the following steps: 
✓ Ultrasound guided Erector Spinae Plane Block (ESPB): 
In group A only: after induction of general anesthesia, all patients will be 
placed in lateral position with the operated side upwards, an ESPB expert 
(at least 20 ESPB completed) performs the block as follows: 
▪ Skin a sepsis with chlorhexidine, and sterile draping will be 
performed, and the ultrasound high frequency linear probe will be 

sheathed. 
▪ Scanning will be done in the longitudinal plane 3 cm parasagittal 
from the midline on the operated side, as defined by Forero et al. 
2016. The tip of the T6 transverse process will be identiﬁed by 
progressively downgrading from C7. When the T6 transverse 
process is in the middle of the image and the pleura is visualized, 
the A22-gauge, 80mm needle (Stimulex D, B-Braun, Germany) is 
inserted in-plane and guided to the middle of the transverse 
process of T6 in a cephalad- caudad direction until the tip of the 
needle is placed into the fascial plane on the deep aspect of the 
erector spinae muscle. 
▪ The conﬁrmation of the correct location of the needle tip in the 
fascial plane deep to the erector spinae muscle is realized by 
injecting 1 to 2 mL of saline to view the elevation of the erector 
spinae muscle from the transverse process without distending the 
muscle. Finally, 20 ml of bupivacaine 0.25% with epinephrine 
1/1000 concentration, 250 mg magnesium sulphate (mgso4) and 4 
mg dexamethasone were injected. 
✓ Near the end of surgery, all patients will receive preemptive 
intravenous paracetamol (1000 mg), ketorolac (30 mg), and 
after full recovery a rescue opioid in the form of nalbuphine 
titration 5 mg intravenously will be given when the verbal 
Numerical Rating Scale (VNRS) is ≥ 3, with a maximum 
dose of 60 mg per day. 
✓ we will continue paracetamol (1000mg)/6 h and ketorolac 
15 mg/8 for the first 24 hrs. postoperative. 
2.7. Outcome measures of the study: 
 Our primary outcomes are recording total postoperative 
nalbuphine consumption during the first 24 hrs. postoperative and time 
to ﬁrst rescue analgesia by registered nurses. While, the secondary 
outcomes include postoperative assessment of verbal Numerical Rating 
Scale (VNRS) at rest and at movement which is a self-report tool, most 
often used to measure pain intensity, where a person verbally rates their 
pain on a scale of 0 to 10. Zero represents "no pain," and 10 represents 
"the worst imaginable pain", opioid-related side effects specifically: 
Ramsay Sedation Scale (table.1) (5), pruritus (no itching=0, itching=1), 
respiratory 
depression 
(defined 
as 
respiratory 
rate<10/min 
or 
Spo2<90%) and simplified PONV impact scale for evaluation of PONV 
severity (no nausea or vomiting =0, nausea =1, Retching or mild 
vomiting =2, Two or more episodes of vomiting within a 30-minute 
period  =3) (6) at the same time points during the ﬁrst 24 hrs. 
postoperatively by registered nurses, in addition to patient satisfaction 
(completely satisfied or completely dissatisfied) (7). 
Table 1: Ramsay Sedation Scale (5) 

 
 
 
2.7. Sample size calculation:  
The sample will be calculated based on the comparison of medians 
between two independent groups; the expected median (IQR) in group 1 
is 4 (3-6) and in group 2 is 5 (4-6) (Durey et al., 2023), with a pooled 
interquartile range of approximately 2.5. The sample was 102 (51 
participants) in each group at a 95% CI and a Power of the test 80%. 
 
2.8. Statistical Analysis: 
 All data will be collected, tabulated, and statistically analyzed 
using SPSS 22.0 for Windows (SPSS Inc., Chicago, IL, USA) & 
MedCalc 13 for Windows (MedCalc Software bvba, Ostend, Belgium). 
Data will be tested for normal distribution using the Shapiro-Wilk 
test. Qualitative data were represented as frequencies and relative 
percentages. Chi-square test (χ2) and Fisher's exact test will be used to 
calculate the difference between qualitative variables as indicated. 
Quantitative data will be expressed as mean ± SD (Standard deviation) 
for parametric and median and range for non-parametric data.  
Independent t-test and Mann-Whitney test will be used to calculate 
the difference between quantitative variables in two groups for 
parametric and non-parametric variables, respectively.  
All statistical comparisons are two-tailed, with a significance level of P-
value ≤0.05 indicating significant, p<0.001 indicating a highly 
significant difference, while P> 0.05 indicates a non-significant 
difference. 
2.8. Ethical Considerations: 
Written consent was obtained from all patients and the study was 
approved from the research ethical committee at the Faculty of 
Medicine, Zagazig University (IRB#5386/ 8-7-2025). The work will be 
performed uniformly with The Code of Ethics of the World Medical 
Association (Declaration of Helsinki) for studies involving humans.