Does local anesthesia at mid-trimester amniocentesis decrease pain experience? A randomized trial in 220 patients. Reducing pain with genetic amniocentesis-A randomized trial of subfreezing versus room temperature needles. Does local anesthesia decrease pain perception in women undergoing amniocentesis? Thermoregulatory effects of spinal and epidural anesthesia during cesarean delivery.
To evaluate whether local anesthesia decreases patients' pain experience during mid-trimester amniocentesis.
                In a randomized trial, one group did not receive local anesthesia while, in another group, lignocaine 1% was injected subcutaneously prior to amniocentesis. Five different scoring systems were used to evaluate patients' pain experience.
                Two hundred and twenty women entered the study: 114 received local anesthesia, while 106 did not. The mean (SD) Visual Analog Scale was 1.4 (1.5) on a 0-10 scale (range 0-7.6). Some 97% of patients described the procedure as not painful or bearable, 79% had expected the procedure to be more painful and 59% reported the amniocentesis to have a comparable discomfort as venous blood sampling; 98% of women declared they would undergo an amniocentesis again if indicated. There were no statistical differences between both randomization groups.
                Mid-trimester amniocentesis is not a painful procedure. Local anesthesia does not affect pain experience during amniocentesis. To determine whether pain associated with second trimester genetic amniocentesis is decreased by using subfreezing rather than room temperature needles.
                Subjects were randomized to a -14 degrees C or room temperature (20-22 degrees C) 22-gauge spinal needle. Patients, blinded to allocation, recorded anticipated and actual pain before and after the procedure, respectively, using a 0-10 visual analog scale with 0 = no pain and 10 = excruciating pain.
                Thirty-three subjects were randomized to room temperature and 29 subjects to subfreezing needles. Anticipated pain was similar in room temperature, 5.1 +/- 1.7, and subfreezing groups, 4.9 +/- 2.0, respectively (p = 0.6). Actual pain was also similar in the room temperature, 3.6 +/- 2.0, and subfreezing groups, 2.8 +/- 2.0, respectively (p = 0.14). Similar numbers of subjects in the room temperature and subfreezing groups reported less actual pain (20 vs. 18), greater actual pain (4 vs. 4) or no difference in pain (9 vs. 5) than anticipated (p = 0.6).
                A subfreezing 22-gauge spinal needle does not decrease perceived pain associated with second trimester genetic amniocentesis. The null hypothesis is that local anesthesia does not decrease pain perception during amniocentesis.
                We performed a prospective randomized study comparing local anesthesia (1% lidocaine) with no anesthesia before amniocentesis in a racially diverse population. Immediately after the procedure, subjects were asked to assess their pain using both a Visual Analogue Scale and a 101-point Numerical Rating Scale.
                Two hundred four women were enrolled; 101 women received local, 102 women received no local, and 1 woman declined the amniocentesis after randomization. There was no difference in pain perception between the 2 groups as measured by either the visual analogue scale or the numeric rating scale (P = .28 and .18 respectively). The correlation coefficient between the 2 pain scales was strong with 0.86 for the local group and 0.92 for the no local group, (P < .001).
                Administration of local anesthesia before amniocentesis does not decrease maternal pain perception. Hypothermia is likely to develop faster during spinal anesthesia than epidural anesthesia. A natural consequence of the rapid temperature decrease during spinal anesthesia is that the shivering threshold will be reached sooner and that more shivering will be required to prevent further hypothermia. We tested the hypotheses that the onset of hypothermia is more rapid and the onset and intensity of shivering earlier during spinal than epidural anesthesia.
                Patients undergoing cesarean delivery were randomly assigned to spinal anesthesia or epidural anesthesia. Spinal anesthesia was induced by injecting 2 mL 0.5% dibucaine into the L4-L5 interspace. Epidural anesthesia was induced with 20 mL 2% mepivacaine injected into the L2-L3 interspace. Thermal comfort and shivering were scored by a blinded observer.
                Fifteen patients given each type of anesthesia had upper sensory levels > or =T4 dermatome. Sensation was entirely absent from the leg during spinal anesthesia, but lower block levels were near S5 during epidural anesthesia. Tympanic membrane temperatures initially decreased faster during spinal anesthesia, but subsequently decreased at a rate of 0.5 degrees C/h in both groups. The onset and incidence of shivering (detected qualitatively) did not differ significantly between the two groups, but shivering intensity was significantly reduced during spinal anesthesia. Furthermore, the shivering thresholds were 36.4+/-0.3 degrees C (mean+/-SD) during spinal anesthesia versus 37.1+/-0.4 degrees C in those given epidural anesthesia (P=.006). There were no clinically important differences in thermal comfort with the two kinds of neuraxial anesthesia.
                We failed to confirm our hypothesis, but for an unexpected reason: Thermoregulation was impaired more by spinal anesthesia than epidural anesthesia. It seems likely that in our patients spinal anesthesia inhibited thermoregulatory control more than epidural anesthesia because it better blocked sensory input from the legs.
In general, women who undergo amniocentesis could be informed that pain during procedure is minor and that there is currently insufficient evidence to support the use of local anaesthetics, leg rubbing or subfreezing the needle for pain reduction during procedure.