الفهرس 
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Abstract
Traditionally, epidural needle insertion and catheter placement is a blind technique, where the epidural space is identified by palpation of anatomical landmarks and loss of resistance to air technique when the needle passes through the ligamentum flavum. Palpation is inaccurate and depends on the anesthesiologist’s level of experience therefore blocks failure and complications are common.
Ultrasound imaging allows the anesthesiologist to visualize the structures within the vertebral canal: ligamentum flavum, epidural space and thecal sac, through the interlaminar spaces between the adjacent vertebrae that permits passage of ultrasound waves into the vertebral canal- acoustic windows. If an acoustic window between two vertebral laminae can be identified, it will likely permit the passage of a needle into the epidural space.
The aim of this study was to compare the percentage of successful first epidural puncture attempts and epidural catheter placement when ultrasound scanning of the neuraxial structures was done before the procedure versus that when using the traditional technique.
The present study was carried out on 60 adult patients aged 20-60 years, ASA physical status class I and II, admitted to “Alexandria University hospitals” for elective orthopedic and lower abdominal surgeries.
Exclusion was done for patients with any contraindication to epidural placement such as low fixed cardiac output states, coagulopathy or infection at the site of needle insertion, neurological or neuromuscular disease, allergy to local anaesthetic drugs, hypovolemia or shock.
Patients were divided into two equal groups (thirty patients each) in a randomized manner using the closed envelope method.
group A: Lumbar epidural catheter was inserted by the original landmark-based technique; i.e. needle insertion was based on palpating the interspinous spaces by the anesthesiologist.
group B: Ultrasound was the assisting tool for the process of lumbar epidural catheter insertion as regards interspinous space identification and needle direction.
Evaluation of patients was carried out through proper history taking, clinical examination and all needed laboratory investigations (including a complete blood count and a coagulation profile).
On arrival to the operating room, an intravenous access was secured. All patients were given 0.01-0.1 mg midazolam and 50 mg ranitidine intravenously, preloaded with 500 ml of ringer solution and were attached to multichannel monitor.
Patients were randomly allocated into two equal groups according to the method of insertion of the epidural catheter:
group A, the epidural catheter was placed using the standard technique, under sterile conditions, the defined insertion point was infiltrated with lidocaine 2%. A 16-gauge epidural needle was utilized for locating the lumbar epidural space by the loss of resistance to air technique. Then, the depth of the needle was marked and recorded using the markings on the needle, then 19-gauge epidural catheter was inserted 5 cm passed the loss of resistance depth.
group B, the epidural catheter was inserted by the ultrasound assisted technique using a curvilinear probe, 2-5MHZ attached to a sonosite ultrasound machine. The transducer was initialy placed in parasagittal articular process view at the level of the sacrum. Once it was identified, the probe was moved in a cephalad direction to identify the intervertebral lumbar spaces till reaching the desired level. With transverse plane scanning, the most superficial reflective surface to the probe scan was the spinous process of the vertebrae underlying the probe. The shadow of the spinous process appeared and disappeared as the probe was moved over them. When there was no superficial reflecting bony surface, this was an interspace. The intervertebral level was marked on the skin by marker pen with a transverse line passing through the midpoint of the transducer. Then, the probe was held parallel to the long axis of the vertebral columns lightly angled toward the midline to visualize ligamentum flavum - dura complex and to determine the angle of insertion of the needle and the depth of epidural space
After aseptic preparation , the epidural puncture was carried out utilizing the labeled landmarks for needle introduction. In both groups, if the first puncture failed, redirection of the needle was done in the four different directions. If redirection failed, reinsertion was done at a different level.
Once the epidural catheter was confirmed in place, epidural analgesia was achieved using a bolus of 10 ml of 0.25 % bupivacaine followed by an epidural infusion of the same concentration at a rate of 5 ml/hour.
After epidural catheter insertion, balanced general anaesthesia was performed using propofol (2 mg/Kg) and fentanyl (2 μg/Kg). Endotracheal intubation was facilitated by atracurium (0.5 mg/Kg). Maintenance of anaesthesia was achieved using isoflurane to maintain stable arterial blood pressure in addition to atracurium increments. By the end of the operation, residual neuromuscular blockade was reversed by neostigmine (0.05 mg/Kg) and atropine (0.01 mg/Kg) followed by extubation.
Patients were observed for 48 hours in PACU to maintain epidural analgesia by infusion of 4ml bupivacaine 0.125% per hour and to evaluate analgesic efficacy, side effects, and complications
The following parameters were measured: Demographic data: age (years), gender, BMI (kg/m2), type and duration of surgery(minutes) were measured and recorded. The visibility of the neuraxial structures in ultrasound group as lamina, posterior complex (ligamentum flavum, posterior dura) and anterior complex (anterior dura–anterior longitudinal ligament) were recorded. First attempt success rate of epidural space identification was recorded, number of needle redirections, needle reinsertion attempts, success rate of epidural catheter placement and total time needed for epidural catheter insertion were recorded (minutes). Complications as intravascular catheterization, dural puncture and neural injury were recorded.
Comparing the two groups, there were insignificant statistical differences regarding age, weight, and BMI. Significantly higher success rate of first attempt of epidural space identification was recorded in group B, the number of needle redirections was significantly lower in group B, needle reinsertions attempts were also lower in group B. No significant difference as regards epidural failure rate was recorded as two cases of epidural failure was recorded in each group. A significant increase in time needed for epidural catheter placement was recorded in group B, There was no significant difference between two groups as post-operative complications.