Comparison of mean arterial pressure in continuous spinal anaesthesia versus ultrasound-guided combined psoas compartment-sciatic nerve block for hip replacement surgery in elderly high-risk patients: A prospective randomised study

Seventy patients over the age of 60 years with ASA (the classification of the American Society of Anaesthesiologists) III or IV physical status who underwent elective hip replacement surgery were included. Before participating in the study, the mental function and confusion states of patients were evaluated using Mini-Mental Status Examination (MMSE). Written informed consent was obtained from all participating patients. Patients were informed about the Visual analogue scales (VAS) before surgery. The age, weight and height of the patients, ASA physical status, preoperative electrocardiogram findings, mean arterial blood pressure (MBAP), heart rate (HR) and oxygen saturation values and the presence of additional disease such as hypertension (systolic/diastolic tension > 160/95 mmHg) and coronary artery disease were recorded. Thromboprophylaxis was provided using a low dose subcutaneous injection (40 mg) of low molecular weight heparin (Clexane'Registered Trademark', Aventis Intercontinental, France) 12 hours prior to surgery for all patients. Before transfer to the operating room, patients were assigned either to the CSA group (n = 35) or to the PCSNB group (n = 35) using a computer generated random number table. Ringer’s lactate solution was given intravenously at 1 to 2 mL/kg/hour via 18-gauge cannula in a forearm peripheral vein and standard monitoring included invasive arterial pressure, electrocardiography and pulse oximetry was established in the operating room. All patients in both groups were pre-medicated with intravenous (IV) midazolam (1 mg) before the procedure of anaesthesia. All anaesthesia procedures were performed by two experienced anaesthetists. In the PCSNB group, psoas compartment block was performed using modified Winnie technique. After lateral decubitus position with the side to be operated uppermost and with the hip and knees flexed was provided for each patient, the skin over the lumbar paravertebral region was prepared by coating with sterile drapes. The 7 MHz ultrasound probe (Esaote, Firenze, Italy) was placed to the area (approximately 3-4 cm lateral and parallel to the lumbar spine). After the L3 spinous process was identified, the transverse process of L3 was located moving the probe horizontally. Then the local anaesthetic was infiltrated into the skin and an insulated stimulation needle (Stimuplex'Registered Trademark'––A Needle, 150 mm/20 G, Braun Medical, Melsungen, Germany) connected to a nerve stimulator (Stimuplex'Registered Trademark', HNS 11, Braun Medical, Melsungen, Germany) was introduced along the long axis of the ultrasound probe. A current strength for nerve stimulator was 0.5 to 0.8 mA at 1 Hz. The ultrasound guidance needle was slowly advanced under to the posterior part of the psoas muscle and the lumbar plexus was confirmed when ipsilateral quadriceps muscle contraction was observed. Following negative aspiration, the mixture of 30 mL local anaesthetic solution (10 mL 2% lidocaine + 1 mL 1:200.000 epinephrine + 19 mL 0.25% bupivacaine) was administered to the psoas compartment. The spread of local anaesthetic in the psoas compartment was demonstrated by ultrasound.After psoas compartment block was completed, the sciatic nerve block was applied according to the method described by Karmakar et al. The sciatic nerve was localised within the sub-gluteal space (the area between the hyper-echoic perimysium of the gluteus maximus and the quadratus femoris muscles). Then a needle with the same characteristics connected to a nerve stimulator delivering a current of 0.5 to 0.8 mA at a frequency of 1 Hz was inserted in the long axis of the ultrasound probe and advanced slowly towards the sciatic nerve. After foot plantar flexion indicating sciatic nerve stimulation was observed, 20 mL of the same anaesthetic solution was administered to the sciatic nerve following negative aspiration. The patient was then turned to the supine position and iliac crest block, with 5 mL of the same local anaesthetic solution was performed. In the CSA group, CSA was performed in the L3-L4 interspaced with the patient in lateral decubitus position with the side to be operated uppermost after cleaning and draping. The epidural space was identified with a Crawford needle and a 22-G (Spinocath'Registered Trademark', B. Braun, Melsungen, Germany) catheter with a 27-G Quincke spinal needle was advanced through the epidural space until cerebrospinal fluid was observed in the catheter. Then, the spinal catheter was advanced 2-4 cm into the intrathecal space and fixed using sterile tape. After the cerebrospinal fluid was aspirated, 2.5 mg isobaric 0.5% bupivacaine was injected manually while the patient was in a supine position.In both groups, the sensory block level was tested using pinprick tests and the motor block level was evaluated with the Modified Bromage scale (scale 0 = full flexion of foot, knee and hip, i.e. no motor block; scale 1 = full flexion of foot and knee, unable to hip flexion; scale 2 = full flexion of foot, unable to knee and hip flexion; scale 3 = total motor block; unable to foot, knee, and hip flexion) three times with an interval of 5 minutes. Sensory and motor block tests were performed bilaterally to evaluate possible epidural spread of the local anaesthetic. When sensory block (a loss of pin prick sensation) was not reached to the level of T12 within 10 minutes in the CSA group, additional 2.5 mg of isobaric bupivacaine 0.5% was administered through the catheter at 5-min intervals by limiting the total dose of 15 mg until a T12 level of the sensory block was achieved. When the satisfactory block level was provided, surgery was initiated in both groups. General anaesthesia protocol was administered for patients with three unsuccessful attempts to reach to spinal space in CSA group and for block procedure in PCSNB group. Also, if adequate surgical anaesthesia was not achieved after 30 minutes on patients of both groups, techniques were considered as failure and general anaesthesia protocol was administered for these patients. Continuing infusion of propofol at the speed of 10-50 microg/kg/min was planned for each patient with discomfort during operation. Patients required propofol infusion exceeding 50 microg/kg/min were considered to be unsuccessful blockade. Oxygen was delivered with a face mask and lactated Ringer's solution (5 mL/kg/h) was administered to all patients during surgery. Colloid solutions and paced red cells when necessary (haematocrit level < 30%) were used to treat perioperative blood loss. Patients' MABP, HR and oxygen saturation values were recorded at the beginning of anaesthesia procedure and surgery, every 5 minutes during surgery and at 1 hour after surgery by an observer who was blinded to study groups. Ephedrine (IV, 10-15 mg) was administered in the case of hypotension (a 30% decrease in systolic blood pressure compared with preoperative values) and atropine (IV, 0.5 mg) was applied when bradycardia (the heart rate < 45 beats/minute) was observed. Socio-demographic characteristics (age, body mass index, co-morbidities), the application time of anaesthetic technique (the time between the onset and end of anaesthesia procedure), duration of the block procedure (the time from the start of the anaesthetic procedure to the development of full motor block), duration of surgery (the time from the start of the surgical incision to the completion of surgery), highest sensory block level, the amount of intraoperative blood loss (weighing the sponges used during surgery plus the amount of blood in the suction bottle), anaesthetic complications and the number of patients required analgesics and sedatives during the block and surgical procedure were recorded. All surgical procedures were performed by the same three surgeons using the same surgical technique.After surgery, patients with intensive care requirements were transferred to the intensive care unit (ICU) and patients with stable clinical status were transferred to the orthopaedic ward. An anaesthesiologist blinded to group allocation visited the patients and postoperative side effects such as nausea, vomiting and bradycardia were recorded. Also, postoperative pain was evaluated at rest using a 10-cm VAS (0 cm = no pain; 10 cm = worst pain possible) and pain scores were recorded at 30 min and 1st, 2nd, 4th, 6th, 12th and 24th hours post-operatively.In the CSA group, morphine of 200 microg was administered through the subarachnoid catheter at the end of surgery for postoperative analgesia; the spinal catheter was removed two hours after completion of surgery. The presence of PDPH (increased pain intensity upon standing up from a supine position) was questioned in patients of the CSA group postoperatively. In the PCSNB group, morphine (0.1 mg/kg, subcutaneously) was administered to the patients at the end of surgery to provide postoperative analgesia. In the case of VAS > 3 in both groups, rescue analgesia was provided with IV tramadol 50 mg. The reversal time of the motor block and the number of patients required rescue analgesic in groups at first 24 hours postoperatively were recorded. On the postoperative first day, the MMSE was completed to detect the presence of postoperative confusion and the results were compared with the preoperative values.