25-gauge Whitacre Needle Research Articles

Optimum programmed intermittent epidural bolus interval time between 8 mL boluses of Ropivacaine 0.1% with sufentanil 0.3 μg/mL with dural puncture epidural technique for labor analgesia: A biased-coin up-and-down sequential allocation trial

ObjectiveThe combination of dural puncture epidural (DPE) technique and programmed intermittent epidural bolus (PIEB) is a novel alternative labor analgesia regimen providing rapid analgesia onset and improved analgesia quality. However, the optimum PIEB settings for using the DPE technique remain unclear. DesignBiased-coin up-and-down sequential allocation design. SettingLabor analgesia. PatientsForty nulliparous women requesting labor analgesia. InterventionsDural was punctured using a 25-gauge Whitacre needle. 12 mL of 0.1% ropivacaine with 0.3 μg/mL of sufentanil was used for initiation. Labor analgesia was maintained using the same solution with a fixed 8 mL volume beginning 1 h after initiation. The interval for the first patient was 60 min and varied for subsequent patients according to the biased-coin design (groups 60, 50, 40, and 30; interval 60, 50, 40, and 30 min, respectively). MeasurementsThe primary outcome was adequate analgesia, defined as no request of patient-controlled epidural analgesia or provider boluses for 6 h after the epidural analgesia initiation or until the maternal cervix was fully dilated, whichever came first. The secondary outcomes included sensory blockade level, motor strength, maternal hypotension, and pruritus. ResultsThe estimated effective interval in 90% of participants was 41.5 min (95% CI 39.5–43.5 min) and 40.5 min (95% CI 33.7–47.5 min) by the truncated Dixon and Mood method and the isotonic regression method, respectively, for the 40 women included. The proportions of patients with the highest sensory block level achieving or above T6 were 60%, 26%, 27%, and 0% in groups 30, 40, 50, and 60, respectively. One patient presented a Bromage score of 1. There was a low incidence of hypotension in all the groups with no need for vasopressor treatment. ConclusionsThe optimum PIEB interval time between 8 mL boluses of ropivacaine 0.1% and sufentanil 0.3 μg/mL when using the DPE technique was approximately 41 min.

Quality of Labor Analgesia with Dural Puncture Epidural versus Standard Epidural Technique in Obese Parturients: A Double-blind Randomized Controlled Study.

The dural puncture epidural technique may improve analgesia quality by confirming midline placement and increasing intrathecal translocation of epidural medications. This would be advantageous in obese parturients with increased risk of block failure. This study hypothesizes that quality of labor analgesia will be improved with dural puncture epidural compared to standard epidural technique in obese parturients. Term parturients with body mass index greater than or equal to 35 kg · m-2, cervical dilation of 2 to 7 cm, and pain score of greater than 4 (where 0 indicates no pain and 10 indicates the worst pain imaginable) were randomized to dural puncture epidural (using 25-gauge Whitacre needle) or standard epidural techniques. Analgesia was initiated with 15 ml of 0.1% ropivacaine with 2 µg · ml-1 fentanyl, followed by programed intermittent boluses (6 ml every 45 min), with patient-controlled epidural analgesia. Parturients were blinded to group allocation. The data were collected by blinded investigators every 3 min for 30 min and then every 2 h until delivery. The primary outcome was a composite of (1) asymmetrical block, (2) epidural top-ups, (3) catheter adjustments, (4) catheter replacement, and (5) failed conversion to regional anesthesia for cesarean delivery. Secondary outcomes included time to a pain score of 1 or less, sensory levels at 30 min, motor block, maximum pain score, patient-controlled epidural analgesia use, epidural medication consumption, duration of second stage of labor, delivery mode, fetal heart tones changes, Apgar scores, maternal adverse events, and satisfaction with analgesia. Of 141 parturients randomized, 66 per group were included in the analysis. There were no statistically or clinically significant differences between the dural puncture epidural and standard epidural groups in the primary composite outcome (34 of 66, 52% vs. 32 of 66, 49%; odds ratio, 1.1 [0.5 to 2.4]; P = 0.766), its individual components, or any of the secondary outcomes. A lack of differences in quality of labor analgesia between the two techniques in this study does not support routine use of the dural puncture epidural technique in obese parturients.

Journal-related Activities and Other Special Activities at the 2020 American Society of Anesthesiologists Meeting.

Journal-related Activities and Other Special Activities at the 2020 American Society of Anesthesiologists Meeting.

Combined spinal-epidural anesthesia in a mild thrombocytopenic patient with antiphospholipid antibody syndrome.

Combined spinal-epidural anesthesia in a mild thrombocytopenic patient with antiphospholipid antibody syndrome.

Monitoring of Sedation during Neuroaxial Blockade

Study objective: The arousal state changes during spinal anesthesia. It is not clear if BIS and others devices could monitor the induced neuroaxial blockade sedation. Our objective was evaluate BIS and entropy values when spinal anesthesia is done. Design: We developed a prospective study. Patients: 40 patients were included in this study, ASA I-III, over 60 years old, undergoing spinal anesthesia, without premedication scheduled for orthopedics procedures. Intervention: Spinal anesthesia was performed with the unseated volunteer in the lateral decubitus position with a 25-gauge Whitacre needle at L2-L3 space, andanesthesia was done with 12 mg of 0.5% hyperbaric bupivacaine. Patients were positioned supine for 5 min after spinal anesthesia. Measurements: Observer’s Assessment of Alertness/Sedation OAA/S, response (RE) and state entropy (SE) and BIS, and standard hemodynamic measures. Main results: Statistical analysis were performed by Wilcoxon test or ANOVA, p 0.05). Conclusions: The spinal anesthesia decreased the cortical activity and these were founded by OAA/S scale and depth anesthetics monitors. OAA/S was a more sensitive value of this induced sedation. BIS and RE showed a better correlation with OAA/S scale than SE.

Parche hemático epidural en el tratamiento de cefalea postpunción dural grave en cirugía mayor ambulatoria

We report a case of postdural puncture headache (PDPH) after outpatient hysteroscopy under spinal anesthesia in which a 25-gauge Whitacre needle was used. Symptoms of PDPH appeared 6 hours after surgery. The headache improved with oral caffein and intravenous corticosteroids and the patient was discharged after 24 hours. Later, she was attended twice in the emergency departments of 2 hospitals, where she received conventional treatment (analgesics and corticosteroids). Eleven days after the surgical procedure, an epidural blood patch was performed. Within 12 hours the incapacitating symptoms had improved markedly and resolution was complete 2 months after surgery. PDPH worthy of blood patch treatment is a rare complication of spinal anesthesia with pencil-point needles. Clear diagnostic protocols are required if satisfactory treatment is not to be delayed and unnecessary suffering is to be prevented.

Regional Anesthesia for a Parturient with Venous Sinus Thrombosis and Placental Abruption Undergoing Fractional Heparin Therapy

THE increased incidence of thrombosis and hypercoagu-lability during pregnancy are well recognized and require anticoagulation for symptomatic sequelae. The following case illustrates our perioperative treatment of a patient with vaginal bleeding while undergoing treatment for a transverse sinus thrombosis.

L’implant contraceptif à l’étonogestrel (Implanon®) serait-il faillible ?

We report a case of paradoxical presentation of a postural postdural puncture headache secondary to dural puncture with a 25-gauge Whitacre needle for combined spinal-epidural anesthesia. This 27-year-old female patient presented to the emergency department with elevated blood pressure and a global headache 9 days after administration of epidural anesthesia for a spontaneous vaginal delivery after an uncomplicated pregnancy. The patient reported that the headache was more intense when lying down and immediately improved when she sat or stood up from a recumbent position. The patient was discharged from emergency department after an improvement following treatment with labetalol, ondansetron, ketorolac, and fluid resuscitation.

The Characteristics of Clinical Anesthesia Based on the Duration of Lateral Decubitus in Low Dose Hyperbaric Bupivacaine Induced Unilateral Spinal Block

Background: When attempting a unilateral spinal anesthesia, many factors must be considered including patient's position, density and amount of the local anesthetics, needle design, injection speed. We evaluated a duration of lateral decubitus with low dose hyperbaric bupivacaine for maximizing the benefit. Methods: Hyperbaric 0.5% bupivacaine 6 mg was administered slowly through a 25-gauge Whitacre needle to 60 ASA 1-2 patients undergoing unilateral lower extremity surgery. The patients were randomly allocated to four groups based on the duration of lateral decubitus after spinal anesthesia: 5 minutes in Group I; 10 minutes in Group II; 15 minutes in Group III; 20 minutes in Group IV. Circulatory variables, sensory and motor block level were recorded. Results: The circulatory variables were stable in all patients. In the Group I, the success rate of unilateral motor block was significantly lower than other groups. In the Group IV, the success rate of unilateral sensory block was significantly higher than group I. In the Group II, III, IV, the patient's satisfaction scores were significantly higher than Group I. Conclusions: When unilateral spinal anesthesia was attempted with 0.5% hyperbaric bupivacaine 6 mg, cardiovascular stability was achieved in the groups that patients are kept in a lateral decubitus for more than 5 minutes after spinal injection, and patient's higher satisfaction scores were achieved in the unilateral motor block and in the groups that patients are kept in a lateral decubitus for more than 15 minutes after spinal injection.

Diplopia: a complication of dural puncture.

Diplopia: a complication of dural puncture.

Unilateral spinal block for outpatient knee arthroscopy: a dose-finding study

Study objective To evaluate the onset time, success rate, and recovery profile of unilateral spinal anesthesia produced with 4 mg, 6 mg, and 8 mg of 0.5% hyperbaric bupivacaine. Design Prospective, randomized, blinded study Setting Outpatient anesthesia unit at a University Hospital. Patients 90 ASA physical status I and II outpatients, who were scheduled for elective knee arthroscopy. Interventions After standard intravenous midazolam premedication (0.05 mg/kg) and crystalloid infusion (7 mL/kg) were given, patients were placed in the lateral decubitus position on the operative side, and randomly allocated to receive spinal block with either 4 mg (Group 4, n = 30), 6 mg (Group 6, n = 30), or 8 mg (Group 8, n = 30) of 0.5% hyperbaric bupivacaine injected slowly (3 mL/min) with the needle orifice directed toward the dependent side using a 25-gauge Whitacre needle. The lateral decubitus position was maintained for 15 minutes. Measurements and main results The onset time of surgical block was 13 ± 5 minutes in Group 4 and 10 ± 4 minutes in Group 6 (p = 0.006), and 9 ± 4 minutes in Group 8 (p = 0.002). The maximum level of sensory block on the operative and nonoperative sides was, respectively, T 10 (T 12–T 6) and / (/–L 2) in Group 4 (p = 0.0005), T 8 (T 12–T 6) and / (/–L 5) in Group 6 (p = 0.0005), and T 7 (T 12–T 5) and / (/–T 10) in Group 8 (p = 0.0005). A strictly unilateral sensory block was observed in 27 Group 4 patients (90%), 28 Group 6 patients (93%) and 23 Group 8 patients (77%) (p = 0.28). Complete unilateral motor block was observed in 29 Group 4 patients (97%), 28 Group 6 patients (93%), and 28 Group 8 patients (93%) (p = 0.80). No failed blocks were reported. Complete regression of spinal anesthesia required 71 ± 20 minutes in Group 4 (range: 40 to 110 min), 82 ± 25 minutes in Group 6 (range: 30 to 160 min), and 97 ± 37 minutes in Group 8 (range: 50 to 120 min) (p = 0.003). Conclusions Hyperbaric bupivacaine 4 mg injected slowly through pencil-point directional needles in patients who are maintained in the lateral decubitus position for 15 minutes provided a surgical block that was mostly restricted to the operative side and adequate to perform knee arthroscopy, with a faster recovery profile than when a 6 mg or 8 mg dose was used.

Hypothermia and excessive sweating following intrathecal morphine in a parturient undergoing cesarean delivery

Objective: Intrathecal morphine has been used for the relief of postoperative pain following cesarean delivery. We report a case of postoperative hypothermia down to 33.6°C associated with excessive sweating in patient undergoing elective cesarean delivery under spinal bupivacaine anesthesia who received intrathecal morphine for postoperative pain management. Case Report: A healthy 31-year-old multigravida presented for elective cesarean delivery. Following prehydration with 500 mL hemaccel, she had a subarachnoid block, using hyperbaric bupivacaine 12 mg and morphine 200 μg, via a 25-gauge Whitacre needle. In the recovery room, 3 hours after induction of spinal anesthesia, the patient's sublingual temperature was 33.6°C and she was noted to be sedated and sweating excessively. During the next 2 hours, the patient was still hypothermic despite active warming. She also complained of severe nausea, vomiting, and moderate pruritis. Following administration of naloxone 400 μg sedation, vomiting, and pruritis were relieved. Also, the patient experienced excessive shivering, and her body temperature started to increase in association with a concurrent decrease of sweating. The postoperative hypothermia and excessive sweating in our patient may be related to the cephalad spread of the intrathecal morphine within the cerebrospinal fluid (CSF) to reach the level of opioid receptors in the hypothalamus, causing a perturbation of the thermoregulatory center. This effect could be counteracted by administration of naloxone. Conclusions: Intrathecal morphine may cause disruption of thermoregulation resulting in hypothermia associated with excessive sweating. Reg Anesth Pain Med 2003;28:140-143.

Complications with 25-gauge and 27-gauge Whitacre needles during combined spinal-epidural analgesia in labor

Needle size and shape may influence the incidence of paresthesias, post-dural puncture headache and other complications during combined spinal-epidural (CSE) procedures. We have noted a relatively high incidence of transient paresthesias during placement of the spinal needle during CSE for labor analgesia. The purpose of this study was to compare the occurrence of paresthesia and post-dural puncture headache in parturients who received CSE analgesia with either a 25-gauge or 27-gauge Whitacre needle. In a prospective observational study, data were gathered from 478 consecutive women receiving labor analgesia. Incidence, duration, and character of any paresthesias upon spinal needle placement and the incidence and treatment of headache were recorded. The incidence of paresthesia with the two needles was similar (16% with 25-gauge vs15.4% with 27 gauge) but the incidence of post-dural puncture headache was higher with the 25-gauge needle (4% vs 0.7% with 27 gauge, P < 0.05). Our data suggest that with Whitacre needles, 27-gauge might be preferable to 25-gauge needles to reduce the rate of post-dural puncture headache in parturients but that they do not alter the incidence of transient paresthesias.

Does Pregnancy Protect Against Intrathecal Lidocaine-Induced Transient Neurologic Symptoms?

We investigated the incidence of transient neurologic symptoms (TNS) after the use of hyperbaric lidocaine as compared with hyperbaric bupivacaine in patients undergoing cesarean delivery under spinal anesthesia. Two hundred women scheduled for cesarean delivery were randomly allocated to receive spinal anesthesia with 75 mg hyperbaric lidocaine 5% (n = 100) or 12 mg hyperbaric bupivacaine 0.75% (n = 100). Spinal anesthesia was administered to all patients in the sitting position with a 25-gauge Whitacre needle. The level of sensory blockade, time to full recovery, and intraoperative hemodynamic profile were noted in all patients. The patients were interviewed postoperatively for three consecutive days to detect the occurrence of TNS. The incidence of TNS was zero (95% confidence interval 0%–3%) in both the Lidocaine and the Bupivacaine Groups. Our results indicate that the frequency of postoperative TNS does not exceed 3% in patients undergoing cesarean delivery at term using hyperbaric lidocaine 5% or hyperbaric bupivacaine 0.75%. Implications Transient neurologic symptom (TNS) can follow spinal anesthesia and manifests as back pain radiating to the legs, resolving spontaneously. Spinal anesthesia for cesarean delivery was performed with either hyperbaric lidocaine 5% (n = 100) or hyperbaric bupivacaine 0.75% (n = 100). TNS was not noted in any patient.

▪ An In Vitro Study of Dural Lesions Produced by 25-Gauge Quincke and Whitacre Needles Evaluated by Scanning Electron Microscopy

▪ An In Vitro Study of Dural Lesions Produced by 25-Gauge Quincke and Whitacre Needles Evaluated by Scanning Electron Microscopy

An in vitro study of dural lesions produced by 25-gauge Quincke and Whitacre needles evaluated by scanning electron microscopy

Background and Objectives: A study using scanning electron microscopy showed that although the laminas forming the dura mater are concentric and parallel to the surface of the medulla, the fiber layers' orientations are different in each sub-lamina, dispelling the conventional knowledge that all the fibers of the dura are arranged in a parallel direction. Thus, this study evaluated the dural lesions produced by Whitacre and Quincke spinal needles in the external and internal surface of the dura mater of the lower spine area in an attempt to gain more insight into the pathophysiology of postdural puncture headaches (PDPH). Methods: The T11-L4 dural membranes from 5 fresh (immediately after extraction of organs for transplantation), male patients declared brain dead, ages 23, 46, 48, 55, and 60 years, were excised by anterior laminectomy. Morphologic orientation of the membrane and normal pH were maintained with an apparatus designed for this purpose. One hundred punctures (20 on each sample) at 90-degree angles were done with a new needle each time, 50 with 25-gauge Whitacre and 50 with 25-gauge Quincke needles. Half of the punctures with the Quincke needles were done with the bevel in parallel direction to the axis of the spinal cord, and the rest with the bevel perpendicular to it. Fixation in solutions of 2.5% glutaraldehyde phosphate buffer, followed by dehydration with acetone, was done 15 minutes after the punctures. After acetone was removed at ideal conditions of temperature and pressure, the specimens were then metallized with carbon followed by gold and inspected under a scanning electron microscope. Results: Twenty-five of the Whitacre and 23 of the Quincke punctures were found for evaluation. There were no differences in the cross-sectional area of the punctures produced by the Whitacre or Quincke needles on the dura. The area of the dural lesions produced by 25-gauge Quincke needles, 15 minutes after they have been withdrawn, was 0.023 mm 2 (confidence interval [CI] 95%, 0.015 to 0.027) in the external aspect (epidural surface) and 0.034 mm 2 (CI 95%, 0.018 to 0.051) in the internal aspect (arachnoid surface) of the dural sac. The area of the lesions produced by the 25-gauge Whitacre needles was 0.026 mm 2 (CI 95%, 0.019 to 0.032) and 0.030 mm 2 (CI 95%, 0.025 to 0.036) in the external and internal surfaces of the dural sac, respectively. There were no significant differences in the cross-sectional areas of the punctures produced by the 25-gauge Whitacre or 25-gauge Quincke needles. Moreover, with Quincke needles the dural lesions closed in an 88.3% (CI 95%, 86.3 to 92.4) and 82.7% (CI 95%, 74.1 to 90.9) of their original sizes in the epidural and arachnoid surfaces, respectively. With Whitacre needles, the closure occurred in an 86.8% (CI 95%, 83.8 to 90.3) and 84.8% (CI 95% 81.7 to 87.3) in the dural and arachnoid surfaces, respectively. However, there were differences in the morphology of the lesions. The Whitacre needles produced coarse lesions with significant destruction in the dura's fibers while the Quincke needles produced a “U”-shaped lesion (flap) that mimics the opened lid of a tin can, regardless of the tip's direction. Conclusions: The needles produced lesions in the dura with different morphology and characteristics. Lesions with the Quincke needles resulted in a clean-cut opening in the dural membrane while the Whitacre needle produced a more traumatic opening with tearing and severe disruption of the collagen fibers. Thus, we hypothesized that the lower incidence of PDPH seen with the Whitacre needles may be explained, in part, by the inflammatory reaction produced by the tearing of the collagen fibers after dural penetration. This inflammatory reaction may result in a significant edema which may act as a plug limiting the leakage of cerebrospinal fluid. Reg Anesth Pain Med 2000;25:393-402.

An In Vitro Study of Dural Lesions Produced by 25-Gauge Quincke and Whitacre Needles Evaluated by Scanning Electron Microscopy

An In Vitro Study of Dural Lesions Produced by 25-Gauge Quincke and Whitacre Needles Evaluated by Scanning Electron Microscopy

The epidural potato − and beyond

Dr Tuckey's potato model for teaching epidural puncture deserves high praise. It is simple, portable and convincing to students at all stages, and in any language [1]. The model is also adaptable to demonstrating the loss-of-resistance-to-negative-pressure test (or ‘suck-and-see’ technique) that I have used exclusively as a safety measure for lumbar or thoracic subarachnoid puncture in humans, and for cisternal puncture in experimental animals [2]. This old and much neglected technique prevents accidental sequestration of any spinal injectate in the subdural space between the pia arachnoid and the dura mater − a nuisance that otherwise occurs in 5–10% of spinal injections [3, 4]. To adapt Dr Tuckey's model for subarachnoid puncture: 1Take a large, washed potato free of wrinkles. Slice in half, taking care to avoid cutting through an ‘eye’ dimple near the circumference of the cut surface. 2Dry the cut surface of the chosen half. 3Wrap a sheet of kitchen plastic film loosely over the cut and dried surface, and secure a gas-tight seal around the circumference with two or three tightly stretched rubber bands, leaving a very slight air pocket between the plastic film (representing the pia-arachnoid membrane) and the cut surface of the potato (representing the inner surface of the dura mater). 4Take a 4-cm 18-gauge hypodermic needle as an introducer and insert it into the butt end of the potato, aiming for the cut surface and advance a 25-gauge Whitacre needle through the introducer (clinically, a 27-gauge Whitacre needle is ideal but, for this artificial model, the stiffer 25-gauge is needed to overcome the more resistant texture of a raw potato). 5Remove the stilette and firmly attach an empty 2-ml syringe to ensure a gas-tight fit. 6Immerse the potato slant-wise in a glass of water and observe the cut surface of the potato. 7While advancing the Whitacre needle, distract the plunger of the attached syringe with middle finger and thumb while exerting counter pressure on the barrel rim with the extended forefinger, and retract the plunger to a volume of 1.75–2.0 ml. This will create a negative pressure of approximately − 600 mmHg, transmitted to the needle orifice [2]. 8Continue to advance the 25-gauge needle very carefully while applying vacuum and an assistant steadies the ‘dura’ until the needle orifice appears. At that instance, the transmitted vacuum ‘snaps’ the ‘pia-arachnoid’ onto the needle point, penetrating the ‘pia’ and collapsing the artefactual subdural space, as water spurts back into the vacuum syringe. 9The needle orifice has evaded the subdural space and is safely within the subarachnoid space. The specialty has waited a long time for a simple bench model to demonstrate the advantages of the ‘suck-and-see’ technique for subarachnoid puncture and its three intrinsic virtues of improved safety, efficacy and parsimony at all spinal levels from the cisterna magna downwards. Dr Tuckey's simple model makes a significant contribution to that educational goal.

Complications with 25G and 27G Whitacre Needles During Combined Spinal-Epidural Analgesia in Labor

Needle size and shape may influence the incidence of paresthesias, post-dural puncture headache and other complications during combined spinal-epidural (CSE) procedures. We have noted a relatively high incidence of transient paresthesias during placement of the spinal needle during CSE for labor analgesia. The purpose of this study was to compare the occurrence of paresthesia and post-dural puncture headache in parturients who received CSE analgesia with either a 25-gauge or 27-gauge Whitacre needle. In a prospective observational study, data were gathered from 478 consecutive women receiving labor analgesia. Incidence, duration, and character of any paresthesias upon spinal needle placement and the incidence and treatment of headache were recorded. The incidence of paresthesia with the two needles was similar (16% with 25-gauge vs 15.4% with 27 gauge) but the incidence of post-dural puncture headache was higher with the 25-gauge needle (4% vs 0.7% with 27 gauge, P < 0.05). Our data suggest that with Whitacre needles, 27-gauge might be preferable to 25-gauge needles to reduce the rate of post-dural puncture headache in parturients but that they do not alter the incidence of transient paresthesias.

Intrathecal anesthesia with ketamine

Background and Objectives. Intrathecal anesthesia is the method of choice for transurethral prostate resection in the United Kingdom, despite its associated hypotension. Intrathecal ketamine with epinephrine has been used for lower limb surgery with minimal cardiovascular disturbance. Because cardiovascular stability might be advantageous in this group of elderly patients, we undertook this study to determine if intrathecal ketamine was a suitable intrathecal anesthetic agent for transurethral prostate surgery. Because of the high incidence of side effects and inadequate analgesia, the study was terminated after only ten patients had been recruited. Methods. Ten ASA I to III males were studied. Spinal anesthesia was performed with a 25-gauge Whitacre needle at the L2–L3 or L3–L4 space. The dose of ketamine was determined by a sequential allocation technique after initial empirical doses of 0.5 and 0.75 mg/kg. Sensory and motor block were monitored using pinprick and modified Bromage score, respectively. If spinal anesthesia was inadequate at any time, a general anesthetic was administered. Results. At doses higher than 0.7 mg/kg, intrathecal ketamine produced both motor and sensory block. The onset of motor block was within 2–3 minutes, peaked in 5–10 minutes, and lasted 30–60 minutes. Sensory block took 5–20 minutes to reach its maximal height. Maximum sensory block height varied from L1 to T7. Despite adequate block to pinprick, half the patients sensed the diathermy and were given a general anesthetic. The incidence of severe psychotomimetic side effects was 30%. Conclusions. Intrathecal ketamine at doses of 0.7–0.95 mg/kg produces sensory and motor block. The frequency of psychomimetic disturbance, inadequate analgesia, and short duration of action preclude its use as a sole anesthetic agent.