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PubMed1990

[Transient medium- and deep-tone hearing disorders following spinal anesthesia].

In a prospective study, 100 patients who underwent general surgical or urological operations under spinal anesthesia were examined to determine whether there was a relation between the anesthesia and postoperative hearing loss. Audiograms were performed preoperatively and as the 1st, 2nd, 3rd, and 5th postoperative days. It was found that 16 patients had impairment of hearing. The average ages of these patients were similar to those of the total population. The hearing loss was typical: only the frequencies between 125 and 2000 Hz were affected. It began on the 2nd day after spinal anesthesia and disappeared within 3 days without special therapy. The cause of this typical hearing loss after spinal anesthesia is a drop in cerebrospinal fluid pressure transmitted to the perilymph via the cochlear aqueduct. The change in the endoperilymphatic pressure difference results in a change in the oscillation of the basilar membrane. Because 16% of patients may suffer hearing loss after spinal anesthesia, it seems reasonable from a medicolegal point of view to explain the possibility of defective hearing to the patient.

Adult↗

PubMed1998

Prophylactic ephedrine and hypotension associated with spinal anesthesia for cesarean delivery.

Hypotension commonly accompanies induction of spinal anesthesia for cesarean section. To determine whether intravenous ephedrine prophylaxis would benefit prehydrated obstetrical patients presenting for elective cesarean section, we studied 30 patients randomly assigned to one of three experimental groups. All patients were preloaded with crystalloid (15 ml/kg), given spinal anesthesia and positioned with left uterine displacement (LUD). During induction, all patients received a 2 ml intravenous bolus and intravenous infusion of the study drug or placebo. The control group (n=10) received a saline bolus and saline infusion, the bolus group (n=10) received an ephedrine bolus (10 mg) and a saline infusion and the infusion group (n=10) received a saline bolus and a two-stage ephedrine infusion (20 mg over 12 min). After induction of anesthesia, systolic blood pressure decreased in the first 5 min in all groups. Hypotension occurred in 6/10 control patients, 5/10 bolus patients and 5/10 infusion patients. The amount of supplemental ephedrine required to treat hypotension did not differ among groups. Although the efficacy of ephedrine prophylaxis for hypotension associated with spinal anesthesia for elective cesarean section cannot be established by the small number of patients studied, this practice does not appear to be clinically relevant at the doses studied.

Clinical Trial↗

PubMed1997

Treatment of hypotension after hyperbaric tetracaine spinal anesthesia. A randomized, double-blind, cross-over comparison of phenylephrine and epinephrine.

BACKGROUND: Despite many advantages, spinal anesthesia often is followed by undesirable decreases in blood pressure, for which the ideal treatment remains controversial. Because spinal anesthesia-induced sympathectomy and management with a pure alpha-adrenergic agonist can separately lead to bradycardia, the authors hypothesized that epinephrine, a mixed alpha- and beta-adrenergic agonist, would more effectively restore arterial blood pressure and cardiac output after spinal anesthesia than phenylephrine, a pure alpha-adrenergic agonist. METHODS: Using a prospective, double-blind, randomized, cross-over study design, 13 patients received sequential infusions of epinephrine and phenylephrine to manage hypotension after hyperbaric tetracaine (10 mg) spinal anesthesia. Blood pressure, heart rate, and stroke volume (measured by Doppler echocardiography using the transmitral time-velocity integral) were recorded at baseline, 5 min after injection of tetracaine, and before and after management of hypotension with epinephrine and phenylephrine. Cardiac output was calculated by multiplying stroke volume x heart rate. RESULTS: Five min after placement of a hyperbaric tetracaine spinal anesthesia, significant decrease in systolic (from 143 +/- 6 mmHg to 125 +/- 5 mmHg; P < 0.001), diastolic (from 81 +/- 3 to 71 +/- 3; P < 0.001), and mean (from 102 +/- 4 to 89 +/- 3; P < 0.001) arterial pressures occurred. Heart rate (75 +/- 4 beats/min to 76 +/- 4 beat/min; P = 0.9), stroke volume (115 +/- 17 to 113 +/- 13; P = 0.9), and cardiac output (8.0 +/- 1 l/m to 8.0 +/- 1l/m; P = 0.8) did not change significantly after spinal anesthesia. Phenylephrine was effective at restoring systolic blood pressure after spinal anesthesia (120 +/- 6 mmHg to 144 +/- 5 mmHg; P < 0.001) but was associated with a decrease in heart rate from 80 +/- 5 beats/min to 60 +/- 4 beats/min (P < 0.001) and in cardiac output from 8.6 +/- 0.7 l/m to 6.2 +/- 0.7 l/m (P < 0.003). Epinephrine was effective at restoring systolic blood pressure after spinal anesthesia (119 +/- 5 mmHg to 139 +/- 6 mmHg; P < 0.001) and was associated with an increase in stroke volume from 114 +/- 12 ml to 142 +/- 17 (P < 0.001) and cardiac output from 7.8 +/- 0.6 l/m to 10.8 +/- 1.1 l/m (P < 0.001). CONCLUSIONS: Epinephrine management of tetracaine spinal-induced hypotension increases heart rate and cardiac output and restores systolic arterial pressure but does not restore mean and diastolic blood pressure. Phenylephrine management of tetracaine spinal-induced hypotension decreases heart rate and cardiac output while restoring systolic, mean, and diastolic blood pressure.

Adrenergic Agonists↗

PubMed1996

Intravenous ketorolac tromethamine worsens platelet function during knee arthroscopy under spinal anesthesia.

Ketorolac prolongs bleeding time and inhibits platelet aggregation and platelet thromboxane production in healthy, awake volunteers. However, platelet function was recently shown not to worsen after ketorolac was given during general anesthesia. The purpose of this study was to investigate platelet function changes during a standardized spinal anesthetic and surgery, as well as after a single intraoperative dose of intravenous (IV) ketorolac. The study comprised 30 ASA physical status I patients undergoing spinal anesthesia for knee arthroscopy. Subjects were randomized to receive either ketorolac 60 mg IV 15 min after skin incision or placebo IV. Platelet function testing consisted of an Ivy bleeding time, platelet aggregometry with adenosine diphosphate (ADP) and collagen, thromboelastography (TEG), and serum thromboxane B2 (TxB2) assays. Platelet function testing was performed: 1) 15 min prior to the performance of spinal anesthesia; 2) 10 min after surgical skin incision; and 3) 45 min after administration of study drug. The placebo group demonstrated no changes in any platelet function variable during spinal anesthesia and surgery relative to preoperative values. The ketorolac group, however, demonstrated a significant increase in bleeding time from postincision to poststudy drug data points (213 +/- 60s to 275 +/- 85s, mean +/- SD; P < 0.01). Further, platelet aggregometry to collagen was diminished in the ketorolac group from preoperative to poststudy drug data points (90.8% +/- 7.6% to 60.5% +/- 32.5%; P < 0.01). Platelet aggregometry with ADP, however, was unchanged in the ketorolac group. Platelet TxB2 production decreased dramatically in the ketorolac group from preoperative to poststudy drug data points (157.2 +/- 129.4 to 0.3 +/- 0.3 ng/mL; P < 0.01). Platelet function does not appear to be accentuated during spinal anesthesia as it is during general anesthesia. Unlike during general anesthesia, platelet function during spinal anesthesia is impaired, with respect to bleeding time and platelet aggregometry to collagen, by a single intraoperative dose of IV ketorolac.

Adolescent↗

PubMed1996

[Spinal anesthesia with 2% plain lidocaine for ultrasonically guided vaginal oocyte retrieval].

Spinal anesthesia with 3 ml of 2% plain lidocaine was administered to 10 women for ultrasonically guided vaginal oocyte retrieval. Spread of anesthesia was assessed by skin vasodilatation, change of skin texture, loss of goose flesh reflex, and loss of cold as well as pin-prick sensation, and we studied time to complete motor block, time to two-segment regression, time to full motor and sensory recovery, ambulation time, haemodynamic parameters, and postoperative complications. The highest sensory block assessed by pin-prick was up to Th 8.3 +/- 3.4 10 min following spinal anesthesia. All patients had complete motor block and this was achieved at 9.0 +/- 1.7 min. Times to two-segment regression, full motor and sensory recovery, and ambulation were 84.5 +/- 31.0, 147.5 +/- 24.7, 176.5 +/- 23.2, and 203.3 +/- 50.0 min, respectively. No serious side effects were observed during the operation and postoperatively. We concluded that 3 ml of 2% plain lidocaine provided adequate spinal anesthesia for ultrasonically guided vaginal oocyte retrieval.

Adult↗

PubMed2001

Transient radiculopathy after 5% lidocaine or 0.75% bupivacaine spinal anesthesia in 3 surgical positions.

The present study was conducted to compare the incidence of transient radicular irritation (TRI) after spinal anesthesia with 5% lidocaine or 0.75% bupivacaine in the supine, prone, and lithotomy surgical positions. A non-rAndomized survey approach was used. The convenience sample consisted of 243 adults receiving spinal anesthesia for elective surgery at 1 of 3 hospitals. Patients were questioned by telephone postoperatively to determine whether they had experienced TRI. Statistical analysis using the Fisher exact test revealed no significant difference in TRI incidence between local anesthetics in the supine or prone position groups. In the lithotomy position group, the incidence of TRI was significantly higher in patients receiving 5% lidocaine. Further, chi 2 testing revealed no significant difference in TRI incidence between surgical position groups when position alone was considered. The findings suggest that TRI after spinal anesthesia occurs more frequently with 5% lidocaine than with 0.75% bupivacaine only when patients undergo surgery in the lithotomy position. Providers need to consider the risks and benefits of 5% lidocaine when selecting an agent for spinal anesthesia, especially with patients undergoing surgery in the lithotomy position. When lidocaine is used, providers should discuss TRI as a risk of spinal anesthesia with patients during preanesthetic counseling.

Adult↗

PubMed1995

Quantitative assessment of differential sensory nerve block after lidocaine spinal anesthesia.

BACKGROUND: Recent technology allows for quantitative and selective measurement of A beta, A delta, and C fiber nerve transmission. To gain further insight into the physiology of differential block after lidocaine spinal anesthesia, the function of these different fibers was quantitatively measured over time, and these measurements were correlated with regression of anesthesia to pinprick, touch, cold, and tolerance of tetanic electrical current (equivalent to surgical incision). METHODS: Six volunteers received lidocaine spinal anesthesia with 50 mg lidocaine (5% in dextrose). Cutaneous current perception thresholds at 2,000, 250, and 5 Hz, which stimulate A beta, A delta, and C fibers, respectively, were determined at L2-L3 (medial aspect above knee) before and every 10 min after spinal anesthesia. Dermatomal levels to pinprick, touch, and cold were assessed every 5 min after spinal anesthesia. Tolerance to tetanic electrical stimulus was assessed at L2-L3 every 10 min after spinal anesthesia. RESULTS: Differential block was demonstrated by the sequential return of sensation to touch, pinprick, and cold at L2-L3. Recovery of function of A beta, A delta, and C fibers correlated with return of sensation to touch (R2 = 0.7, p = 0.03), pinprick (R2 = 0.75, p = 0.02), and cold (R2 = 0.67, p = 0.04) respectively. Loss of tolerance of surgical anesthesia corresponded to return of A beta current perception thresholds to baseline, whereas current perception thresholds for A delta and C fibers were still increased to greater than baseline (p = 0.025). CONCLUSIONS: Differential sensory block during spinal anesthesia is due to different recovery profiles of A beta, A delta, and C fibers. Return of A beta current perception thresholds to baseline correlated with duration of surgical anesthesia as assessed with an electrical stimulation model.

Anesthesia Recovery Period↗

PubMed1997

Sympathovagal effects of spinal anesthesia assessed by the spontaneous cardiac baroreflex.

BACKGROUND: The changes in sympathovagal balance induced by spinal anesthesia remain controversial. The spontaneous baroreflex method allows the continuous assessment of the spontaneous engagement of the cardiac baroreflex, giving an index of sympathovagal balance. The purpose of this study was to follow the effects of spinal anesthesia on spontaneous baroreflex sensitivity. METHODS: Continuous electrocardiogram and noninvasive blood pressure were recorded in 24 patients scheduled for elective inguinal hernia repair and randomly assigned to three groups: (1) no volume loading, (2) volume loading of 15 ml/kg lactated Ringer's solution, and (3) continuous infusion of etilefrine (an ephedrine-like drug). Each patient was studied before, during, and after bupivacaine-induced spinal anesthesia (mean sensory block: T4). Spontaneous baroreflex sensitivity and parameters of time-domain analysis of heart rate variability were calculated from 30 min of recording of each period. RESULTS: No significant change in spontaneous baroreflex slope or parameters of time-domain analysis were observed after regional anesthesia in any group. However, three patients experienced episodes of bradycardia and hypotension in the absence of a high block; these three patients showed an increase in spontaneous baroreflex sensitivity and time-domain parameters. CONCLUSIONS: Using a noninvasive, continuous technique to estimate cardiac sympathovagal balance, no significant variation in autonomic balance induced by spinal anesthesia was observed. However, untoward episodes of bradycardia and hypotension occurred in three patients, who could not be prospectively identified by the parameters studied.

Adjuvants, Anesthesia↗

PubMed2003

Intravenous droperidol causes a reduction in the bispectral index in propofol-sedated patients during spinal anesthesia.

UNLABELLED: We investigated the effect of IV droperidol on the bispectral index (BIS) in conscious and propofol-sedated patients during spinal anesthesia. Thirty minutes after the induction of spinal anesthesia, 20 patients were given 2 mg of droperidol IV without administration of other sedatives (conscious group). Another group of patients were sedated with a propofol infusion to maintain BIS at 60 +/- 5 and were administered IV saline (placebo group; n = 20), droperidol 1 mg (dro-1 group; n = 20), or droperidol 2 mg (dro-2 group; n = 20) in a randomized order and in a double-blinded fashion. Although BIS remained the same in the conscious and placebo groups, it significantly decreased after administration of droperidol in the dro-1 and dro-2 groups. The decrease in BIS was significantly larger in the dro-2 group than in the dro-1 group. These results suggest that an antiemetic dose of droperidol enhances the hypnotic effect of propofol in a dose-dependent manner during spinal anesthesia. IMPLICATIONS: An antiemetic dose of IV droperidol causes a decrease in the bispectral index in patients sedated with propofol during spinal anesthesia. We conclude that droperidol may enhance the hypnotic effect of propofol.

Adult↗

PubMed2002

[Spinal anesthesia in premature infants--indications, technical aspects and results].

PURPOSE: To present our experience with spinal anesthesia in premature and former premature infants, and to focus on technical aspects and pitfalls enlightened with increasing experience. METHODS: The perioperative course of all premature and former premature infants below 60 weeks postconceptual age undergoing spinal anesthesia within an 35-month-period was analyzed. Lumbar puncture was performed while the patient was held seated at L4-5 or L5-S1. Anesthetics included hyperbaric tetracaine or bupivacaine, dose 1 mg/kg with adrenaline. The patients were positioned in the reverse Trendelenburg for 2-3 minutes, and later horizontally. RESULTS: Sixty seven infants (gestational age 30.1 +/- 3.6 weeks, postconceptual age 42.9 +/- 3.4, weight 3234 +/- 1165 grams) underwent spinal anesthesia and surgery. Thirty two had other diseases, including congenital heart (12), lung (15) brain pathology (8) and urological findings (6). Sixty five patients underwent hernia repair and two underwent pyloromyotomy. N2O was added in three infants, and two required general anesthesia. All were found to have lower limb motor blockade postoperatively. Intraoperatively, hypoxemia was diagnosed in two infants, short apnea in two cases and bradycardia in one. The apnea and hypoxemia episodes were successfully treated by reverse Trendelenburg positioning and bag and mask ventilation and the bradycardia that did not respond to tactile stimulation was relieved by atropine. Postoperatively, a short episode of apnea and hypoxemia (one patient) and hypoxemia (one patient) responded to free oxygen administration with/without tactile stimulation. Brief bradycardia (three infants) terminated without intervention. Supplementation and postoperative complication rates resembled previous studies. CONCLUSION: Successful spinal anesthesia in premature and former premature infants depends on close attention to preoperative assessment, patient positioning during and immediately after anesthetic induction, drug dosing and perioperative monitoring. A relatively high dose of local anesthetic should be administered.

Anesthesia, Spinal↗

PubMed2002

[Transient neurologic symptoms after spinal anesthesia with 4% hyperbaric mepivacaine].

This is a case report of transient neurologic symptoms (TNS) after spinal anesthesia with 4% hyperbaric mepivacaine,which have not been reported before. The patient was a 44-year-old man with a meniscus lesion who received spinal anesthesia with 80 mg 4% mepivacaine while undergoing knee arthroscopy. A L3-L4 mid-line approach was used with a 26-gauge Quincke needle and a 21-gauge introducer. The local anaesthetic was injected over approximately 30 s with the aperture of the Quincke needle in a cephalad direction. A transient pain syndrome was observed 4 h after spinal anesthesia, which included symmetric pain and/or dysesthesia in the buttocks and posterior thighs appearing 4 h after recovery from the spinal anesthesia and had a duration of 2 days. The patient stated that the pain radiated through the hips, buttocks, and posterior thighs and extended past the buttocks and lower legs. The pain was described as strong and aching,occasionally decreasing when walking around. It responded well to NSAID and resolved spontaneously within 3 days. No other neurologic symptoms or signs were noted.

Adult↗

PubMedDate not supplied

Intrathecal lipophilic opioids as adjuncts to surgical spinal anesthesia.

BACKGROUND AND OBJECTIVES: Lipophilic opioids, especially fentanyl and sufentanil, are increasingly being administered intrathecally as adjuncts to spinal anesthesia. This review analyzes the efficacy of these opioids for subarachnoid anesthesia. METHODS: Medline search of the literature from 1980 to the present and a survey of recent meeting abstracts are reviewed. RESULTS: A significant number of citations regarding intrathecal lipophilic opioids as adjuncts to spinal anesthesia were found: 59 are cited in this review. Most clinical experience has been in obstetric surgery, but lipophilic spinal opioid administration is being used with greater frequency for other surgical procedures as well. The benefits include reduction of minimal alveolar concentration (MAC) when general anesthesia is combined with spinal anesthesia and enhancement of the quality of spinal anesthesia without prolongation of motor block. Intrathecal fentanyl and sufentanil allow clinicians to use smaller doses of spinal local anesthetic, yet still provide excellent anesthesia for surgical procedures. Furthermore, lipophilic opioid/local anesthetic combination permits more rapid motor recovery; short outpatient procedures are therefore more amenable to spinal anesthesia. Finally, the side-effect profiles of intrathecal lipophilic opioids are now well characterized and appear less troublesome than intrathecal morphine. CONCLUSIONS: The anesthesia-enhancing properties and side-effect profile of lipophilic opioids administered intrathecally suggest significant roles for these agents as adjuncts to spinal anesthesia for obstetric and outpatient procedures.

Adjuvants, Anesthesia↗

PubMed1998

Incidence and time course of cardiovascular side effects during spinal anesthesia after prophylactic administration of intravenous fluids or vasoconstrictors.

UNLABELLED: We studied the time course of arterial hypotension and/or bradycardia requiring treatment during spinal anesthesia and compared the efficacy of i.v. fluid or vasoconstrictor administration for the prevention of these side effects. Patients (n = 1066) were randomly allocated to either a volume group (lactated Ringer's solution 15 mL/kg within 15 min before spinal anesthesia), a dihydroergotamine group (10 microg/kg i.m. 15 min before anesthesia), or a placebo group. All patients breathed O2-enriched air during spinal anesthesia (4 mL of plain 0.5% bupivacaine). With the placebo, there were side effects (mean incidence 22.9%) for up to 45 min after the start of anesthesia. Dihydroergotamine reduced the incidence of side effects, preferentially the late ones, more (mean incidence 11.8%) than fluid administration (mean incidence 16.9%), which was effective only during the first 15 min of anesthesia. Both heart rate and arterial pressure decreased within 15 min before the manifestation of symptoms. In a subgroup of patients, the incidence of side effects (8%) was greatly reduced by the intraoperative application of both sedatives and opioids. We conclude that cardiovascular side effects may occur at any time during spinal anesthesia. Fluid administration reduced the incidence of early events, but dihydroergotamine the late events. IMPLICATIONS: Cardiovascular side effects requiring treatment occurred at any time during spinal anesthesia in our placebo-controlled study, regardless of the prophylactic regimen (fluid infusions versus dihydroergotamine).

Adult↗

PubMed2001

A prospective multicenter trial to determine the incidence of transient neurologic symptoms after spinal anesthesia with phenylephrine added to 0.5% tetracaine.

The addition of vasoconstrictors for spinal anesthesia is controversial, since an increase in the incidence of transient neurologic symptoms (TNS) has been reported. A multicenter, randomized, double-blind study was conducted to assess the effectiveness of spinal anesthesia with phenylephrine in addition to tetracaine as well as the incidence of neurological complications. We studied 64 patients with comparable demographic characteristics who were scheduled for elective surgery for a lower limb, or a gynecological or urological procedure. The patients were allocated randomly into 2 groups. Group P (n = 34) received 0.5% tetracaine in 10% glucose with 0.025% phenylephrine, while group C (n = 30) received 0.5% tetracaine in 10% glucose. Our results showed that only 2 patients (6.7%) in group C experienced TNS, and their symptoms disappeared within 72 hr after anesthesia, while none of the patients (0%) in group P complained of symptoms. The incidence of TNS was thus not significantly different between the two groups. Six hours after the sensory block, group P patients demonstrated sensory disturbance, with the median spinal dermatome corresponding to the L1 segment. Moreover, systolic blood pressure in group P was significantly higher than that in group C, 5 min, 15 min, and 20 min after injection. The incidence of TNS in the present study does not seem to be greater after surgery with spinal anesthesia using 0.5% hyperbaric tetracaine and 0.5 mg phenylephrine than without phenylephrine. Randomized, double-blind, cross-over trials with a larger sample size would be required in the future to obtain more reliable results.

Anesthesia, Spinal↗

PubMed1999

[Urinary retention as a transient neurologic symptom after accidental total spinal anesthesia with mepivacaine hydrochloride].

We report a patient in whom urinary retention as a transient neurologic symptoms (TNS) developed after accidental total spinal anesthesia with mepivacaine hydrochloride. Mepivacaine, an amide local anesthetic, has been used for spinal anesthesia and considered one of the best for spinal anesthesia for its low incidence of TNS. However, we suggest that TNS associated with mepivacaine might not be a rare complication in spinal anesthesia.

Adult↗

PubMed1995

Oral clonidine prolongs lidocaine spinal anesthesia in human volunteers.

BACKGROUND: Premedication with oral clonidine may improve the quality and duration of lidocaine spinal anesthesia, but this effect has not been examined in a quantitative fashion. METHODS: Eight volunteers received 50 mg lidocaine (1.5% dextrose free) both with and without 0.2 mg oral clonidine 1.5 h before spinal anesthesia in a randomized, double-blind, placebo-controlled, crossover fashion. Sensory block was assessed by pinprick, transcutaneous electric stimulation equivalent to surgical incision, and duration of tolerance to pneumatic thigh tourniquet. Motor block at the quadriceps and gastrocnemius muscles was assessed by isometric force dynamometry. Episodes of bradycardia, hypotension, and sedation were recorded. RESULTS: Regression of pinprick was unchanged with clonidine. However, duration of tolerance to electric stimulation was increased at the knee (28 +/- 24 min) and ankle (31 +/- 28 min) with clonidine (P < 0.05). The duration of tolerance to tourniquet-induced pain was increased with clonidine (14 +/- 12 min; P < 0.05). The duration of motor block was increased at the quadriceps (20 +/- 13 min) and gastrocnemius (33 +/- 24 min) muscle groups with clonidine (P < 0.05). Although clonidine decreased systolic blood pressure (13 +/- 4 mmHg, P < 0.003) and heart rate (13 +/- 5 beats/min; P = 0.02), no subjects had hypotension or bradycardia. The incidence of sedation was greater with clonidine than with plain lidocaine (50% vs. 0%, P < 0.04). DISCUSSION: Premedication with oral clonidine prolonged sensory and motor block from lidocaine spinal anesthesia. The exact mechanism whereby oral clonidine prolongs spinal anesthesia remains to be determined.

Administration, Oral↗

PubMed1996

Unilateral spinal anesthesia using low-flow injection through a 29-gauge Quincke needle.

Restriction of sympathetic denervation during spinal anesthesia may minimize hemodynamic alterations. Theoretically, the use of nonisobaric anesthetics may allow unilateral anesthesia and thus restrict sympathetic denervation to one side of the body. The present prospective study investigates the incidence of unilateral spinal anesthesia using hyperbaric bupivacaine 0.5% (1.4 mL, 1.6 mL, 1.8 mL, or 2.0 mL) injected via a 29-gauge Quincke needle with a pump-controlled injection flow of 1 mL/min. In 96 consecutive patients undergoing unilateral surgery of the lower extremities, spinal anesthesia was performed in the lateral decubitus position, which was maintained for 20 min postinjection. Increases in foot temperature of at least 0.5 degrees C were defined as sympathetic blockade. The incidence of unilateral block was not significantly influenced by the amount of bupivacaine. For all 96 patients, the incidence of unilateral sympathetic and complete motor block was 69% and 77%, respectively. Frequency of unilateral sensory block (assessed by pinprick and temperature discrimination) was significantly lower (28%). Strict unilateral spinal anesthesia was achieved in 24 cases (25%). Twenty minutes after injection of the local anesthetic, mean arterial blood pressure decreased significantly in patients with bilateral sympathetic blockade from 87 +/- 8 to 83 +/- 8 mm Hg (P < 0.01) but not in patients with unilateral sympathetic blockade (from 87 +/- 11 to 85 +/- 10 mm Hg). In conclusion, low-flow injection (1 mL/min) of hyperbaric bupivacaine 0.5% via a 29-gauge Quincke needle prevented bilateral sympathetic blockade in more than 69% of the patients. The data further suggest that loss of temperature discrimination alone is not a reliable estimation of sympathetic block.

Anesthesia, Spinal↗

PubMed1993

Effects of ephedrine on indocyanine green clearance during spinal anesthesia: evaluation by the finger piece method.

We measured indocyanine green (ICG) clearance in 20 patients scheduled for elective surgery during spinal anesthesia to determine whether ephedrine affects the hepatic circulation during spinal anesthesia. The clearance was measured by a new noninvasive finger piece method. We found that a decrease in arterial blood pressure secondary to spinal anesthesia significantly reduced ICG, whereas there were no significant changes in ICG clearance in the patients whose arterial blood pressures were maintained at preanesthetic levels by ephedrine. Other hemodynamic variables, heart rate, cardiac index, and stroke volume index, did not change significantly in either group. We conclude that hepatic blood flow is decreased by hypotension due to spinal anesthesia and can be attenuated by ephedrine administration.

Adult↗