Analgesia Before Performing a Spinal Block in the Sitting Position in Patients with Femoral Shaft Fracture: A Comparison Between Femoral Nerve Block and Intravenous Fentanyl

Abstract

We conducted this prospective, randomized study to compare the analgesic effect of femoral nerve block and IV fentanyl administration when given to facilitate the sitting position for spinal anesthesia in patients undergoing surgery for femoral shaft fracture. Five minutes before the placement of spinal block, group FEM patients (n = 10) received a femoral nerve block with lidocaine 1.5% 15 mL, and group IVA patients (n = 10) received IV fentanyl 3 μg/kg. Visual analog scale values during positioning (median and range) were lower in group FEM: 0.5 (0–1) versus 3 (2–6) (P < 0.001). Time to perform spinal anesthesia (mean ± sd) was shorter in group FEM: 1.8 ± 0.7 min versus 3.0 ± 1.1 min (P < 0.05). Quality of patient positioning for spinal anesthesia (0 = not satisfactory, 1 = satisfactory, 2 = good, and 3 = optimal) (median and range) was higher in group FEM: 3 (2–3) versus 1.5 (1–3) (P < 0.005). Patient acceptance was less in group IVA (P < 0.05). In one group IVA patient, an oxygen saturation <90% was recorded during the procedure. We conclude that femoral nerve block is more advantageous than IV administration of fentanyl to facilitate the sitting position for spinal anesthesia in patients undergoing surgery for femoral shaft fractures.

In Brief

IMPLICATIONS: Femoral nerve block produces a more intense analgesic effect than IV administration of fentanyl when given to facilitate the sitting position for spinal anesthesia in patients undergoing surgery for femoral shaft fractures.

Patients with a fracture of the femoral shaft present special problems to the anesthesiologist. The femoral shaft is subjected to major muscle forces that, especially in young patients, can deform the thigh and angulate the bone fragments, thus complicating the intraoperative reduction of the fracture (¹). Therefore, complete paralysis of all the muscles acting on the femur is mandatory. Spinal anesthesia is routinely used at our institution in these patients. However, any overriding of the fracture ends is extremely painful, and the procedure of patient positioning to perform a spinal block always requires the administration of a large amount of IV analgesics. Femoral nerve block has been shown to be an effective method of analgesia for fractured femoral shaft when it is performed either during prehospital management or in the emergency department (^2,3) and also can provide excellent postoperative analgesia (⁴). In this prospective randomized study, we compared the feasibility and analgesic effect of a femoral nerve block compared to IV fentanyl when administered before spinal anesthesia in patients undergoing surgery for fractured femoral shaft.

Methods

After obtaining institutional approval and written informed consent, from September 2002 to November 2003, 20 ASA physical status I and II patients suffering from an isolated femoral shaft fracture were prospectively included in the study. Exclusion criteria were hemorrhagic diathesis, peripheral neuropathy, allergy to amide local anesthetics, mental disorders, and use of analgesics for 8 h before the performance of spinal block. The patients were randomly divided into two groups: group FEM (femoral nerve block) and group IVA (IV analgesia). On arrival in the anesthesia induction room, a visual analog pain scale (VAS) (0 = no pain to 10 = maximal pain) was clearly explained to the patients. An IV catheter was placed, and oxygen saturation was monitored. No premedication was given. Skeletal traction was maintained during the procedure. Group FEM patients received a femoral nerve block using a peripheral nerve stimulator (Stimuplex; Braun, Mesulgen, Germany). The needle was introduced 1 cm lateral to the femoral artery and 1.5 cm below the inguinal ligament. When a current <0.3 mA elicited contractions of the quadriceps femoris muscle with a visible cephalic movement of the patella, 15 mL of lidocaine 1.5% was injected slowly after a negative aspiration test.

Group IVA patients received fentanyl 3 μg/kg IV. In both groups, the time when the treatment drug (lidocaine or fentanyl) was administered was considered as the starting time (T0). Five minutes after T0, the patients were placed in the sitting position, and a spinal block was performed by an anesthesiologist unaware of the patient’s group. Spinal block was performed in the anesthesia induction room. The patient was lying on his or her bed and sat flexed, helped by an assistant, while the skeletal traction was maintained. Local anesthetic skin infiltration was not made. A median approach was used. If the patient reported a VAS ≥4 during placement in the sitting position, the procedure was stopped, and IV fentanyl in 50-μg increments was given. The VAS scores during the performance of femoral nerve block and during placement into the sitting position were recorded. The performance time (defined as the time from the beginning of patient positioning to the end of the performance of spinal anesthesia) and the quality of patient position maintained for spinal anesthetic block placement (0 = not satisfactory, 1 = satisfactory, 2 = good, and 3 = optimal) were also recorded. The VAS score during patient positioning and the quality of patient position were recorded by the anesthesiologist who performed the spinal block. Patient acceptance was evaluated 24 h after surgery by using a two-point score: 1 = good, if necessary, I will repeat it and 2 = bad, I will never repeat it again.

Data were analyzed using SPSS 8.0 for Windows (SPSS Inc, Chicago, IL) and Power and Precision™ (Biostat Inc, Englewood, NJ) software packages. Parametric variables were described as mean ± sd; qualitative variables were described as number (percentage) and as median and range. Student’s t-test, Fisher’s exact test, or Mann-Whitney U-test was used as appropriate to compare the two groups. P < 0.05 was considered significant. A power analysis was performed while designing the study. Allowing an α error of 5% and a β error of 20%, it was estimated that a minimum of 12 patients per group would be required to show a 25% differences in VAS scores at positioning.

Results

Demographics were not significantly different between the groups (Table 1). Time elapsed between trauma and surgery (median and range) was 2.5 days (0–5 days) in group FEM and 2 days (0–5 days) in group IVA. VAS values during positioning (median and range) were lower in group FEM: 0.5 (0–1) versus 3 (2–6) (P < 0.001). In group FEM, VAS during femoral block performance was higher than VAS during positioning for spinal anesthesia (1.5 ± 0.7 versus 0.5 ± 0.5; P < 0.005). Performance time was shorter in group FEM (P < 0.05). Quality of patient positioning for spinal anesthesia (median and range) was better in group FEM: 3 (2–3) versus 1.5 (1–3) (P < 0.005). Supplemental fentanyl (50 μg) was given to one group IVA patient. In one group IVA patient, an oxygen saturation <90% was recorded during the procedure. Patient acceptance was less in group IVA (P < 0.05; Table 1); four patients stated they would never repeat the anesthetic procedure again. No complications were observed during postoperative examination.

Table 1: Demographic Data, VAS Scores, Performance Time, Quality of Position, and Patient Acceptance

Discussion

This prospective, randomized study demonstrates that femoral nerve block is more effective than IV administration of fentanyl to facilitate the sitting position for spinal anesthesia in patients undergoing surgery for femoral shaft fracture. The significant difference in analgesic effect between the groups led us to limit the number of patients to 10 for each group.

The choice of the anesthesia management in patients with a fracture of the femoral shaft is greatly affected by the surgical needs. A fractured femoral shaft is subjected to major muscle forces that, especially in young patients, can deform the thigh and angulate the bone fragments. Therefore, a technique that allows the complete paralysis of all the muscles acting on the femur is mandatory to facilitate the intraoperative realignment of a femoral shaft fracture, especially if surgery has been delayed for more than 3 days (¹). At our institution, these fractures are treated by closed intramedullary nailing in anterograde fashion. The patients are placed in the supine position on the fracture table. The surgical incision is made proximal to the greater trochanter to develop the entry hole for the nail. The trunk and the pelvis are tilted away from the injured limb to facilitate the surgical approach. The nonaffected limb is often abducted or placed in the lithotomy position to facilitate the use of the image intensifier. We routinely use a spinal anesthesia (with or without the placement of an epidural catheter).

The positioning of these patients to perform spinal or epidural anesthetic is often problematic because even a minimal overriding of the fracture ends is extremely painful. To reduce the pain and avoid further soft tissue trauma, we prefer to perform spinal anesthesia in the sitting position while femoral traction is maintained. Despite this practice, administration of a substantial amount of IV analgesics is mandatory during placement of the block.

The femoral nerve block has been used successfully in adults for femoral shaft fracture analgesia in prehospital care or in the emergency departments (^2,3). A fascia iliaca compartment block, which produces a simultaneous block of the femoral and of the lateral femoral cutaneous nerves (⁵), provided good pain relief for patients with femoral shaft fracture when used in prehospital care (⁶). Capdevilla et al. (⁴) reported effective and safe analgesia provided by using continuous femoral blocks for bilateral femoral shaft surgery. Urbanek et al. (⁷) used a three-in-one block in some of their patients to facilitate position for spinal anesthesia, but no patient with a femoral shaft fracture was included in their study.

This is the first prospective, randomized study in which the feasibility and analgesic effect of femoral nerve block and IV fentanyl administration were compared.

A five minute interval between T0 and the performance of spinal anesthesia was chosen to maximize the analgesic effect of fentanyl (⁸); however, we thought that a time interval longer than five minutes could have excessively prolonged the anesthetic procedure. Lidocaine was used for femoral nerve block to obtain a short onset time; however, the use of a long-acting local anesthetic might have allowed more effective postoperative pain relief.

There are several limitations to this study that should be addressed. The issue of blinding was problematic because the drug affecting the central nervous system was administered only in the patients of one of the groups. In fact, even if the anesthesiologist who performed the spinal block and recorded the VAS during patient positioning was blinded, the clinical effects of IV administration of fentanyl were evident in some group IVA patients who complained of drowsiness, face itching, or a “strange feeling.” This might have produced a bias.

Spinal anesthesia was performed in the sitting position on the patient’s bed because it is, in our opinion, the easier way to leave the skeletal traction in place during the procedure. It may be that the use of the lateral position and of a paramedian approach, which requires minimum flexion, could have improved patients’ comfort, thus reducing the difference in analgesic effect between the groups.

The dosage of fentanyl was chosen to obtain potent, short-lasting analgesia with minimal side effects (⁸). An anxiolytic was not given because the aim of the present study was to choose the analgesic effect of the two techniques. It could be that the use of a larger fentanyl dose or the addition of another analgesic (like ketamine) or an anxiolytic may have yielded different results.

Both techniques provided sufficient analgesia to perform spinal anesthesia in the sitting position. In fact, in all but one IVA group patient, the procedure was performed without the administration of supplemental analgesics. However, the analgesic effect of femoral block was significantly better than that produced by IV fentanyl. The analgesic effect and the paralysis of the quadriceps allowed better patient positioning and a shorter spinal anesthesia performance time in group FEM. We think that the administration of a femoral nerve block might be even more useful when the anesthetic procedure is expected to be more complex than a simple spinal anesthesia (e.g., placement of an epidural or lumbar plexus catheter or spinal abnormalities), where the patient must stay in the sitting position for a longer time. Besides the excellent analgesic effect, the procedure used in group FEM showed a high feasibility. Femoral nerve block was easy to perform, even when patients’ legs were placed in traction. The onset of the analgesic effect produced by the femoral nerve block using 1.5% lidocaine was very rapid. The five-minute interval was adequate to establish the analgesic effect in all patients. The placement of spinal block was easier and faster in group FEM than in group IVA. The only disadvantage noted in group FEM was the additional cost for insulated needles and local anesthetic mixture.

We conclude that femoral nerve block is more advantageous than IV administration of fentanyl to facilitate the sitting position for spinal anesthesia in patients undergoing surgery for femoral shaft fractures.