Spinal anesthesia at low and moderately high altitudes: A comparison of anesthetic parameters and hemodynamic changes

A total of 140 consecutive male subjects who were admitted to 2 study institutions at Ataturk University, Medical Faculty, Erzurum, Turkey (1890 metres above sea level) and Sakarya University, Medical Faculty, Sakarya, Turkey (31 metres above sea level) between January 1, 2014 and June 30, 2014 and who were scheduled elective lower extremity surgery with spinal anesthesia were enrolled in this study.All participants were permanently resident at moderately high altitude, as well as sea level. Written informed consent was obtained from all participating patients. Demographic characteristics (age, weight and height) and indications for surgery of the patients were recorded. Before transfer to the operating room, all patients received ringer’s lactate solution intravenously at 1 to 2 ml/kg/hour via 18-gauge cannula in a forearm peripheral vein. Standard monitoring included non-invasive arterial pressure, electrocardiography and pulse oximetry was established for all patients in the operating room. Before the procedure of anesthesia, each patient was premedicated with intravenous (iv) fentanyl (0.1 µg/kg) and midazolam (2 mg). After skin infiltration with 2% lidocain, 26-gauge Quincke's needle was inserted through the L2-3/ L3-4 intervertebral space of sitting position patient. Once free flow of cerebrospinal fluid was obtained, hyperbaric bupivacaine 0.5%, 9mg (1.8mL) was injected intrathecally. Then, the patient was enrolled in the supine position. Sensory block level was tested using pinprick tests and motor block level was evaluated with Modified Bromage scale (scale 0 = full flexion of foot, knee and hip, ie, 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). When the sensory block reached the T12 dermatome, surgery was initiated. If no signs of analgesia were observed within the first 10 min after intrathecal injection, technique was considered as fail and general anesthesia was administered for these patients. Oxygen was delivered with a face mask during surgery; iv midazolam (1 mg) for complaint of discomfort, iv propofol (10 mg/kg) for sedation and fentanyl (0.1 µg/kg) for pain were administered to each patient if necessary. The quality of the anesthesia was evaluated according to total amount of supplementary sedatives and analgesics during surgery. During the operation, patients' mean arterial blood pressure (MABP), heart rate (HR) and oxygen saturation were monitored and recorded every 5 minutes. Ephedrine (iv, 2.5 mg) was administered in 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. Same anesthesia protocol was applied for patients living at moderately high altitude and sea level. The application time of spinal anesthesia, duration of the block procedure (the time from the start of the anesthetic 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, sensory block time (from local anesthetic injection to the recovery of S2) dermatom, motor block duration (the time from local anaesthetic injection to complete motor function recovery), anesthetic complications and total amount of required analgesics and sedatives during surgical procedure were recorded. After surgery, patients were transferred to the orthopaedic ward. The presence of postdural puncture headache (PDPH, increased pain intensity upon standing up from a supine position) was questioned in patients postoperatively. Crystalloid infusions (500 ml, 8-hour intervals) and a nonsteroidal anti-inflammatory drug applied to the patients diagnosed PDPH. If this therapeutic modality was not successful, an epidural blood patch with 10 mL of autologous blood was applied to the patient following the patient’s permission.