Epidural blood flow and regression of sensory analgesia during continuous postoperative epidural infusion of bupivacaine

Epidural blood flow was measured in seven patients undergoing elective abdominal surgery during combined lumbar epidural and general anesthesia. After an initial dose of 20 ml plain bupivacaine 0.5%, a continuous epidural infusion of bupivacaine 0.5% (8 ml/hr) was given for 16 hours for postoperative pain relief. The epidural blood flow was measured by a local 133Xe clearance technique in which 15-35 MBq 133Xe diluted in 1 ml saline was injected through the epidural catheter on the day before surgery (no bupivacaine), 30 minutes after the initial dose of bupivacaine on the morning before surgery, and 8, 12, and 16 hours later during the continuous infusion. Initial blood flow was 6.0 +/- 0.7 ml/min per 100 g tissue (mean +/- SEM). After epidural bupivacaine, blood flow increased in all seven patients to 7.4 +/- 0.7 ml (P less than 0.02). Initial level of sensory analgesia was T4.5 +/- 0.17 (mean +/- SEM). Postoperatively, two patients maintained the initial level of sensory analgesia and low pain score throughout the 16-hour study. In these two patients epidural blood flow remained constant after the initial increase. Flow increased further to 10.3 +/- 0.8 ml/min per 100 g tissue (P less than 0.03) in the other five patients as the level of sensory analgesia regressed postoperatively. These data suggest that changes in epidural blood flow during continuous epidural infusion of bupivacaine, and thus changes in rates of vascular absorption of bupivacaine from the epidural space, may be an important factor contributing to differences in rates of regression of sensory analgesia.     

The effect of 0.5 % ropivacaine on epidural blood flow

Twenty patients scheduled for elective abdominal surgery received epidural analgesia with 20 ml 0.5% ropivacaine or 0.5% bupivacaine. Epidural blood flow was measured by an epidural 133Xe clearance technique on the day before surgery (no local anaesthetic) and again 1 h before surgery, 30 min after injection of the local anaesthetic during continuous infusion (8 ml/h). Median initial blood flow was 5.0 ml/min and 6.0 ml/min per 100 g tissue in patients receiving ropivacaine and bupivacaine, respectively. After epidural bupivacaine, blood flow increased in 8 of 10 patients to 6.9 ml/min per 100 g tissue (P less than 0.05) in contrast to a decrease in 9 of 10 patients to 3.3 ml/min per 100 g tissue after ropivacaine (P less than 0.05), (P less than 0.01 between groups). The median level of sensory analgesia was T3.5 and T4.5 in the ropivacaine and bupivacaine group, respectively (P greater than 0.05). The demonstrated vasoconstrictor effect of epidural ropivacaine may influence the duration of its local anaesthetic effect.     

Venous blood concentrations after subarachnoid administration of bupivacaine

Peripheral venous blood concentrations of bupivacaine were measured in 51 patients given 0.5% (4 ml, 20 mg) or 0.75% (3 ml, 22.5 mg) bupivacaine, both solutions with or without glucose, for spinal anesthesia. The initial absorption of bupivacaine, as measured in peripheral venous blood, was rapid, although the blood concentrations were low. The mean peak concentration (Cmax) did not differ when glucose was added to 0.5 or 0.75% bupivacaine. When glucose-free and glucose-containing bupivacaine groups were combined, 22.5 mg bupivacaine give a significantly higher venous blood concentration than 20 mg of the solution. The mean time between subarachnoid injection and the time when Cmax was reached (tpeak) was influenced by the density of bupivacaine, i.e., the tpeak of bupivacaine with glucose was significantly shorter than with glucose-free solution (35 min; P less than 0.05). No correlation was found between Cmax and the age, height, or weight of the patients, or between Cmax and the maximum cephalad level of analgesia in the different groups. In addition, there was no correlation between tpeak and the age, height, or weight of the patients. The maximal cephalad level of analgesia did not influence tpeak in the different groups (the correlation coefficients less than 0.3).     

Body mass and spread of spinal anesthesia with bupivacaine

The effect of body mass on spinal anesthesia with isobaric 0.5% bupivacaine was examined in 90 patients. The first 50 patients received 3 ml isobaric 0.5% bupivacaine. Another 40 patients, selected at random to receive 3 ml of either hyperbaric or isobaric bupivacaine 0.5%, were then studied. Levels of pin-prick analgesia and motor block were tested during induction, surgery, and recovery. The effects of high spinal anesthesia on peak expiratory flow (PEF) and arterial blood gas tensions were also examined in the last 40 patients. With isobaric bupivacaine, persons with higher than normal BMI [body mass index = weight (kg) divided by height-squared (m2)], or persons who were shorter than normal had higher cephalad spread of anesthesia. With hyperbaric bupivacaine only shorter individuals developed higher levels of anesthesia. Because of considerable interindividual variability, however, these observations are of only limited clinical value in predicting the spread of bupivacaine spinal analgesia. The higher spread of analgesia was associated with a decrease in PEF, whereas, the blood gas tensions remained undisturbed.     

Hyperbaric bupivacaine and hyperbaric cinchocaine: a comparison of their use for spinal anaesthesia

A new spinal analgesic formulation, 'heavy bupivacaine', was compared clinically with a commonly used agent. Sixty patients, who required spinal analgesia for transurethral prostatectomy, received either 1.5 ml of hyperbaric 0.5% cinchocaine (Nupercaine, Percaine, Dibucaine) in 6% dextrose or 2.5 ml of hyperbaric 0.5% bupivacaine (Marcain) in 8% dextrose. The onset, rate of rise, plateau height of the sensory block, reduction in blood pressure and peak expiratory flow rate, and the operative and post-operative blood loss did not differ significantly. Motor blockade was significantly less with bupivacaine. It is concluded that hyperbaric bupivacaine is an acceptable alternative to hyperbaric cinchocaine for spinal analgesia for transurethral prostatectomy.     

Subarachnoid bupivacaine decreases spinal cord blood flow in dogs

Eigtheen mongrel dogs were randomized into two equal groups. Cervical, thoracic and lumbosacral spinal cord and spinal dural blood flows were measured using the radioactive microsphere technique. Blood flow determinations were made prior to, and 20 and 40 minutes following lumbar subarachnoid injection of: (1) 0.4 per cent bupivacaine (20 mg), or (2)0.4 per cent bupivacaine (20 mg) with 1/25,000 epinephrine (200 μg). In dogs given subarachnoid bupivacaine or bupivacaine with epinephrine, the maximum decrease in mean arterial blood pressure (33 per cent) occurred at 40 minutes post-injection. Cardiac index decreased in dogs given subarachnoid bupivacaine (197 ± 11 ml·kg^-1·min^-1 controlvs. 141 ± 19 ml·kg^-1 min^-1 at 40 minutes), while it increased in dogs given bupivacaine with epinephrine (201 ± 11ml·kg^-1·min^-1 - control vs. 252 ± 15 ml · kg^-1 · min^-1 at 40 minutes). Dogs receiving subarachnoid bupivacaine demonstrated a significant decrease in spinal cord blood flow to all regions. Dogs receiving subarachnoid bupivacaine with epinephrine demonstrated a significant decrease in thoracic and lumbosacral spinal cord blood flow; however, cervical cord blood flow remained unchanged. Thoracic and lumbosacral dural blood flows were significantly decreased in both groups following subarachnoid injection. Subarachnoid bupivacaine 0.4 per cent (20 mg) and 0.4 per cent with epinephrine 1/25,000 (200 μg) decrease spinal cord and spinal dural blood flow in dogs.     

Intrapleural analgesia for postthoracotomy pain and blood levels of bupivacaine following intrapleural injection

An epidural type catheter was placed in the pleural space under direct vision before the closure of the chest in 24 patients who underwent thoracotomy for various types of lung or aortic surgery. All patients received intrapleural injections of 20 ml of 0.5 per cent bupivacaine with or without epinephrine as initial pain therapy. Patients also received subsequent doses of a similar volume of 0.375 per cent bupivacaine with epinephrine 1:200,000 up to four times a day for a maximum duration of seven days. Good pain relief was achieved in patients who underwent lateral and posterior thoracotomies. No pain relief was achieved in patients who underwent anterior thoracotomy or in patients in whom there was excessive bleeding in the pleural space. Bupivacaine blood concentrations were measured in 11 patients following the initial dose of 20 ml of 0.5 per cent bupivacaine (with epinephrine 1:200,000 in five of the 11 patients). The mean peak plasma concentration of bupivacaine when used with epinephrine was 0.32 +/- 0.02 microgram.ml-1. The mean peak plasma concentrations of bupivacaine when used without epinephrine was 1.28 +/- 0.48 microgram.ml-1. Our present data show that intrapleural analgesia is useful in the management of postoperative pain in patients who undergo thoracotomy. Our data also show that there is a significant decrease in peak plasma concentrations of bupivacaine when epinephrine is added to the solution (P less than 0.05).     

Interpleural analgesia after thoracotomy

We examined the effects of the following variables on interpleural analgesia after thoracotomy: addition of epinephrine to local anesthetic, thoracostomy drainage, two-catheter placement, and location of catheter tips. Twenty patients were randomized to have one catheter (paravertebral tip location) or two catheters (paravertebral and lateral thoracic wall tip locations). Interpleural catheters were sutured to the parietal pleura by the surgeon at time of wound closure. Patients were then randomly assigned to receive 20 mL of 0.5% bupivacaine with 1:200,000 epinephrine through the single catheter or 10 mL of 0.5% bupivacaine with or without 1:200,000 epinephrine through each of the two catheters while supine. Bupivacaine concentrations in whole blood and in thoracostomy drainage fluid were assayed by gas chromatography. Actual content of bupivacaine in the drainage fluid was calculated. Degree of analgesia was assessed by verbal numerical pain scores over the first 4 h and opioid demand thereafter. Addition of epinephrine to bupivacaine did not influence the degree of analgesia. Approximately 30%-40% of any administered dose of bupivacaine was lost via the thoracostomy tube over a 4-h period. There was no correlation between the true initial dose (100 mg minus thoracostomy drainage) and Cmax. Use of two catheters resulted in significantly less opioid requirements after an initial 8-h period. Failure to achieve adequate interpleural analgesia in postthoracotomy patients may be related to loss of anesthetic via thoracostomy drainage, presence of extravasated blood and tissue fluid in the pleural space, and possibly sequestration and channeling of flow of local anesthetic by restricted motion of an operated lung.(ABSTRACT TRUNCATED AT 250 WORDS)     

Comparison of 0.5% ropivacaine and 0.5% bupivacaine for epidural anesthesia in patients undergoing lower-extremity surgery

Ropivacaine is an amide local anesthetic structurally related to, but appearing less cardiotoxic, than bupivacaine. The authors' investigation was designed in a randomized, double-blind fashion to compare the clinical effectiveness of ropivacaine and bupivacaine in patients undergoing lower-extremity surgery. Forty-five patients were randomized to receive 20 ml of 0.5% ropivacaine or bupivacaine. Intermittent sensory (pinprick) and motor (Bromage score) measurements were made while the block was in effect, and changes in heart rate, blood pressure and amounts of additional analgesics, sedatives and other medications were also recorded. Presence of tourniquet pain and the quality of anesthesia were also assessed. One patient was excluded from analysis; thus, 22 patients each received ropivacaine or bupivacaine. No differences were found in patient or perioperative characteristics between the groups. The quality and extent of sensory and motor blockade between groups were comparable, although bupivacaine was slightly longer acting. Cardiovascular changes, incidence of tourniquet pain, and the amounts of supplemental medications necessary were also similar between groups. The authors found 0.5% ropivacaine and bupivacaine to be clinically similar in both sensory- and motor-blocking characteristics, with the exception that bupivacaine produced a blockade of slightly longer duration. Because ropivacaine is reported to be less cardiotoxic than bupivacaine in animal studies, the similarity of clinical epidural anesthesia may make ropivacaine the preferred agent.     

SPINAL ANAESTHESIA WITH HYPERBARIC BUPIVACAINE: EFFECTS OF CONCENTRATION AND VOLUME WHEN ADMINISTERED IN THE SITTING POSITION

In a double blind study, solutions of 0.5% or 0.75% bupivacainecontaining 8% dextrose were compared with regard to the effectof varying concentration and volume when administered intrathecallyto patients in the sitting position. Ten patients received 3or 4 ml of 0.5% bupivacaine or 2 or 3 mi of 0.75% bupivacaine.Nine patients received 0.5% bupivacaine 2 ml and another ninereceived 0.75% bupivacaine 1.3ml. The use of the 10-mg doseof both solutions was abandoned after nine patients in eachgroup becafse of insufficient cephalad spread. With both solutions,the smallest volumes (bupivacaine 10 mg) had significantly shorterdurations of action than both the larger ones (15–20/22.5mg), between which there were no significant differences.     

The effect of a priming epidural injection of adrenaline on epidural blockade with bupivacaine

Twenty-four patients receiving epidural anaesthesia were studied to test the hypothesis that 1:200,000 adrenaline administered into the epidural space 5 minutes before 20 ml bupivacaine 0.5% would improve nerve block and delay systemic absorption of the local anaesthetic. Group A/B received 20 ml adrenaline 1:200,000 5 minutes before 20 ml bupivacaine 0.5%, group S/BA 20 ml saline followed by 20 ml bupivacaine 0.5% with 100 micrograms adrenaline, and group S/B saline 20 ml followed by 20 ml plain bupivacaine 0.5%. Mean maximum plasma concentrations of bupivacaine tended to be lower in the adrenaline groups. A delay in the time to peak plasma concentration of bupivacaine was noted in the A/B group; this indicated that priming with adrenaline may be effective at delaying early systemic uptake of the local anaesthetic. In both adrenaline groups a more prolonged epidural block and increased efficacy were noted, although this was only significant for the duration of block at T6 (p = 0.023) and duration of motor block at Bromage level 1 (p = 0.016) in group A/B. There seems little clinical advantage in administering adrenaline 5 minutes before bupivacaine.     

Clinical Effects and Maternal and Fetal Plasma Concentrations of Epidural Ropivacaine Versus Bupivacaine for Cesarean Section

Background: Ropivacaine is a new amide local anesthetic structurally similar to bupivacaine and mepivacaine. Previous studies showed that ropivacaine has a similar clinical effect as bupivacaine with regard to sensory anesthesia and slightly less motor blockade than bupivacaine. Ropivacaine appears to be less cardiotoxic and arrhythmogenic than bupivacaine. The clinical and pharmacokinetic effects of 0.5% ropivacaine (5 mg/ml) versus 0.5% bupivacaine (5 mg/ml) when used epidurally for elective cesarean section were investigated.

Methods: Using a randomized, double-blind study design, 60 ASA physical status 1 or 2 term parturients presenting for elective cesarean section received either 0.5% bupivacaine (150 mg) or 0.5% ropivacaine (150 mg) epidurally in appropriate fractionated doses over a 10-min period. Onset, duration, and regression of sensory and motor blockade were noted until complete resolution was observed. Quality of intraoperative anesthesia and abdominal wall muscle relaxation were noted. Maternal plasma concentrations of local anesthetic were determined before anesthetic administration and 5, 10, 20, 30, and 60 min and 2, 3, 6, 8, 12, and 24 h after drug injection in 20 subjects. Umbilical cord blood was obtained at time of delivery for acid-base values and determination of the free and total plasma concentration of local anesthetic. Neonates also were examined for neurobehavioral assessments by Scanlon's and Neurologic and Adaptive Capacity Scores at 2 and 24 h after delivery.

Results: All patients received satisfactory anesthesia for operation. The onset, duration, and regression of sensory blockade were similar for both groups. Onset of degree 1 and 2 motor blockade was faster, and duration of degree 1 motor block was longer in the group receiving bupivacaine. Hemodynamic sequelae were similar between groups. All neonates had 5-min Apgar scores of 7 or greater and normal acid-base values and neurobehavioral assessments. Pharmacokinetic analysis showed that the Cmax was similar for both drugs (1.3 plus/minus 0.09 for ropivacaine and 1.1 plus/minus 0.09 micro gram/ml for bupivacaine). The T1/2 of the terminal decline in plasma concentration was shorter for ropivacaine versus bupivacaine (5.2 plus/minus 0.60 versus 10.9 plus/minus 1.08 h, respectively; P < 0.01). The free (i.e., unbound) concentrations of ropivacaine were approximately twice those of bupivacaine in both maternal and neonatal blood at the time of delivery. The ratio of umbilical vein to maternal vein concentration of unbound drug was 0.72 for ropivacaine and 0.69 for bupivacaine.     

Uteroplacental blood flow measured by placental scintigraphy during epidural anaesthesia for caesarean section

The uteroplacental blood flow was measured before and during epidural anaesthesia for caesarean section in 11 women. The blood flow was measured with dynamic placental scintigraphy. After an i.v. injection of indium-113m chloride, the gamma radiation over the placenta was recorded with a computer-linked scintillation camera. The uteroplacental blood flow could be calculated from the isotope accumulation curve. The anaesthesia was performed with bupivacaine plain 0.5%, 18-22 ml and a preload of a balanced electrolyte solution 10 ml/kg b.w. was given. The placental blood flow decreased in eight patients and increased in three with a median change of -21%, not being statistically significant. No correlation between maternal blood pressure and placental blood flow was found.     

Pharmacokinetics of Bupivacaine after Continuous Epidural Infusion in Infants with and without Biliary Atresia

Background: Continuous epidural infusion of bupivacaine is widely practiced for postoperative pain relief in pediatric patients. However, bupivacaine may induce adverse effects in infants (convulsions or cardiac arrhythmias), likely because of decreased hepatic clearance and serum protein binding capacity. The authors wanted to examine the complex relations between age, [alpha]-1 acid glycoprotein (AAG) concentration, and unbound and total bupivacaine serum concentrations in infants receiving bupivacaine epidurally for 2 days.

Methods: Twenty-two infants aged 1-7 months (12 with biliary atresia and 10 with another disease) received a continuous epidural infusion of 0.375 mg [middle dot] kg-1 [middle dot] h-1 bupivacaine during 2 days (during and after surgery). Unbound and total bupivacaine concentration in serum was measured 0.5, 4, 24, and 48 h after infusion initiation. AAG concentration was measured in serum before and 2 days after surgery. In eight additional infants, the blood/plasma concentration ratio was measured in vitro at whole blood concentrations of 2 and 20 [mu]g/ml. Bupivacaine concentration was fitted to a one-compartment model to calculate basic pharmacokinetic parameters.

Results: No adverse effects were observed. AAG increased markedly after surgery, and the increase was correlated to both age and preoperative AAG concentration. Two infants aged 1.8 months had unbound concentrations greater than 0.2 [mu]g/ml. Clearance of unbound drug significantly increased with age. Because of increased drug binding, clearance of bound drug decreased both with time (from 0.5 to 48 h) and with age. Blood/plasma ratio was 0.77 +/- 0.08 and 0.85 +/- 0.24 at 2 and 20 [mu]g/ml, respectively.     

Combined spinal and epidural anesthesia for cesarean section: a retrospective study with 0.5% hyperbaric bupivacaine

BACKGROUND: We investigated retrospectively the relationship between the intrathecal dose of 0.5% hyperbaric bupivacaine and the use of 2% mepivacaine through an epidural catheter. METHODS: Forty-nine patients undergoing cesarean section with combined spinal and epidural anesthesia (CSEA) were analyzed. They were divided into two groups; with (CSEA group) and without additional epidural injection group (spinal group). RESULTS: In the CSEA group (24 patients received 1.2 +/- 0.4 ml of 0.5% hyperbaric bupivacaine), 5-10 ml of 2% mepivacaine were required to achieve the adequate surgical anesthesia. In the spinal group (25 patients received 1.6 +/- 0.3 ml of 0.5% hyperbaric bupivacaine), cesarean section was performed without additional mepivacaine before delivery. The analgesic level and the amount of fluid infusion were similar in the two groups. However, 20% of patients in the spinal group showed hypotension (systolic blood pressure below 80 mmHg), although no patients in the CSEA group developed hypotension. The amount of ephedrine used before delivery was significantly larger in the spinal group (8.9 +/- 7.7 mg) than in the CSEA group (3.9 +/- 4.3 mg). CONCLUSIONS: Spinal anesthesia induced by 1.2 ml of 0.5% hyperbaric bupivacaine with sequential epidural block induced by 5-10 ml of 2% mepivacaine caused no hypotension during cesarean section.     

Changes of blood pressure and cerebral arterio-venous oxygen content differences (AVDo2) with and without bupivacaine scalp infiltration during craniotomy

In 20 patients subjected to craniotomy for supratentorial cerebral tumours, the effect of scalp infiltration with bupivacaine before incision was evaluated by measuring mean arterial blood pressure (MABP) and cerebral arterio-venous oxygen content differences (AVDO2) repeatedly during the operation. All patients were given halothane 0.5% anaesthesia. Ten patients were given bupivacaine 0.25% and ten patients were given normal saline for scalp infiltration prior to incision. The study was performed in a double-blind randomized fashion. Significantly higher values of MABP (P less than 0.0005) after incision were found in the saline group compared to the bupivacaine group. Significantly lower values of AVDO2 (P less than 0.0005) after incision were seen in the saline group compared to the bupivacaine group. The results indicate that the increase in MABP associated with a decrease in AVDO2, suggesting an increase in CBF and cerebral hyperperfusion, is reduced by using bupivacaine scalp infiltration prior to incision.     

Lack of influence of cimetidine on bupivacaine levels during parturition

The concurrent use of cimetidine as a prophylactic antacid and bupivacaine as a local anesthetic for epidural anesthesia for cesarean section has been promoted. However, cimetidine is known to inhibit clearance of many drugs by reducing hepatic blood flow and by inhibiting cytochrome P-450 enzymes. The purpose of this study was to determine whether cimetidine during epidural anesthesia alters the metabolism, disposition, protein binding, or placental transfer of bupivacaine. Thirty-six patients undergoing cesarean section with 0.5% bupivacaine for epidural anesthesia were studied. Sixteen patients received cimetidine (300 mg IM) 1-4 hr before cesarean section and 20 control patients received sodium citrate (30 ml PO) 10 min preoperatively. Bupivacaine and its inactive metabolite, 2,6-pipecolylxylidine (PPX) were quantitated by gas chromatography/mass spectrometry. Maternal plasma concentration time curves, fetal/maternal ratios at delivery, cord vein/cord artery ratios. PPX/bupivacaine ratios, and maternal and neonatal urinary excretion were compared between the two groups. No significant differences could be found between the groups in any of the outcome variables. However, in the presence of cimetidine, the percentage of unbound bupivacaine significantly increased from 1.36 +/- 0.63 to 1.66 +/- 0.78%. The results suggest that a single 300-mg IM dose of cimetidine does not significantly affect bupivacaine disposition or metabolism in parturients when given 1-4 hr before anesthesia.     

Effects of thoracic paravertebral block with bupivacaine versus combined thoracic epidural block with bupivacaine and morphine on pain and pulmonary function after cholecystectomy

Twenty patients undergoing elective cholecystectomy via a subcostal incision were randomized in a double-blind study to either thoracic paravertebral blockade with bupivacaine 0.5% (15 ml followed by 5 ml/h) or thoracic epidural blockade with bupivacaine 7 ml 0.5% + morphine 2 mg followed by 5 ml/h + 0.2 mg/h, respectively for 8 h postoperatively. Mean initial spread of sensory analgesia on the right side was the same (Th3,4-Th11 versus Th2,6-Th11), but decreased (P less than 0.05) postoperatively in the paravertebral group. All patients in the epidural group had bilateral blockade, compared with three patients in the paravertebral group. In both groups only minor insignificant changes in blood pressure and pulse rate were seen postoperatively. Pain scores were significantly higher in the paravertebral group, as was the need for systemic morphine (P less than 0.05). Pulmonary function estimated by forced vital capacity, forced expiratory volume and peak expiratory flow rate decreased about 50% postoperatively in both groups. In conclusion, the continuous paravertebral bupivacaine infusion used here was insufficient as the only analgesic after cholecystectomy. In contrast, epidural blockade with combined bupivacaine and low dose morphine produced total pain relief in six of ten patients.     

Single bolus compared with a fractionated dose injection technique of bupivacaine for extradural Caesarean section: effect on uteroplacental and fetal haemodynamic state

We studied 26 healthy parturients undergoing elective Caesarean section, allocated randomly to receive extradural block with 0.5% plain bupivacaine in a double-blind manner in either a single bolus or fractionated doses. After a 3-ml test dose, an additional 20 ml of bupivacaine were given over a 5-min period in the single bolus group (n = 13) and over a 25-min period in the fractionated dose group (n = 13). We studied the effects of bupivacaine on blood flow velocities in the maternal placental and non-placental uterine and fetal umbilical arteries before and four times during establishment of extradural block using a pulsed colour Doppler technique. Median sensory block reached T3 in the single-dose group compared with T4 in the fractionated-dose group. Two subjects in each group required i.v. ephedrine to correct transient hypotension (systolic arterial pressure < 90 mm Hg). Blood flow velocity waveform indices of the uterine and umbilical arteries did not differ significantly within or between groups during the study. There was no significant difference in neonatal outcome, as assessed by Apgar scores and umbilical artery pH values. In conclusion, we observed no deterioration in uteroplacental circulation after administration of a single bolus dose of bupivacaine.      

Effects of intrathecal bupivacaine–fentanyl versus bupivacaine–dexmedetomidine in diabetic surgical patients

BackgroundDiabetes mellitus is the most common endocrine disorder encountered during anesthesia. Experimental researches showed that the functional μ opioid receptors in the dorsal horn of spinal cord in diabetics are either reduced or impaired in their function. This prospective study was postulated to differentiate between the effects of either opioid like fentanyl versus nonopioid like dexmedetomidine agents added to spinal bupivacaine in diabetic patients.MethodsSixty diabetic patients of either sex were submitted for elective lower limb orthopedic surgery. Patients were randomly allocated into three equal groups (each group 20 patient): bupivacaine group in which patients received 2.5 ml of hyperbaric bupivacaine 0.5% plus 0.5 mL of normal saline, bupivacaine–fentanyl group in which patients received 2.5 ml of hyperbaric bupivacaine 0.5% plus 25 μg fentanyl in 0.5 mL of normal saline and bupivacaine–dexmedetomidine group in which patients received 2.5 ml of hyperbaric bupivacaine 0.5%, plus 10 μg dexmedetomidine in 0.5 mL of normal saline. Duration and quality of sensory and motor block were assessed.ResultsThe duration of sensory and motor block as well as duration of effective analgesia was significantly longer in the bupivacaine–dexmedetomidine group as compared with both bupivacaine–fentanyl and control bupivacaine groups.ConclusionAddition of intrathecal dexmedetomidine to heavy bupivacaine 0.5% was more advantageous than fentanyl with special regard to its analgesic properties in diabetic surgical patients.