Posture and the spread of hyperbaric bupivacaine in parturients using the combined spinal epidural technique

Effects of neuraxial anesthesia in sitting and lateral positions on maternal hemodynamics in cesarean section: A systematic review and meta-analysis

STUDY OBJECTIVE

During cesarean section, hypotension is a frequent side effect of spinal anesthesia. As a sitting or lateral position is required for spinal anesthesia performance, which of these two positions is more likely to cause intraoperative nausea, vomiting, and hypotension is still unknown. This meta-analysis compared the effects of these two positions on maternal hemodynamics and intraoperative nausea and vomiting.

DESIGN

Systematic review and meta-analysis.

SETTING

Operating room.

PATIENTS

This study included 803 patients from 12 randomized controlled trials (RCTs).

INTERVENTIONS

Neuraxial anesthesia in sitting position vs. lateral position.

MEASUREMENTS

We chose RCTs comparing the effects of spinal anesthesia in the sitting and lateral positions on maternal hemodynamics by thoroughly searching PubMed, Embase, the Cochrane Library, and the Web of Science for articles published from database inception until October 31, 2022. The Cochrane Handbook was used to assess the methodological quality of each RCT; the results were analyzed using RevMan 5.4 software; and the Egger test was used to assess publication bias.

MAIN RESULTS

12 randomised controlled trials with 803 participants were ultimately included in the final analysis. No significant differences were observed between the two positions in terms of the incidence of hypotension(RR, 0.82; 95% CI, 0.58-1.16; P = 0.26; I2 = 66%), lowest systolic blood pressure(MD, -0.81; 95% CI, -7.38-5.75; P = 0.81; I2 = 86%), the dose of ephedrine(MD, -1.19; 95% CI, -4.91-2.52; P = 0.53; I2 = 83%), and number of parturients requiring ephedrine(RR, 0.97; 95% CI, 0.64-1.46; P = 0.88; I2 = 74%). For the incidence of intraoperative nausea and vomiting, there was no statistical difference between the two positions.

CONCLUSION

Parturients undergoing elective cesarean section under spinal anesthesia in the sitting or lateral position experienced similar incidence of hypotension, and there were no significant differences between these two positions in terms of the amount of ephedrine administered or the number of patients needing ephedrine. In both positions, the frequency of nausea and vomiting was comparable. The ideal position for anesthesia can be chosen based on the preferences and individual circumstances of the parturient and anesthesiologist.

Prevention of post-spinal anaesthesia hypotension in caesarean delivery using delayed supine positioning - A randomised controlled trial

Background and Aims

Maternal hypotension is a common and dangerous consequence after a subarachnoid block for a caesarean section. Combining pharmacological methods such as norepinephrine infusion, ondansetron and non-pharmacological methods in delayed supine positioning better impacts the maternal haemodynamic profile. The present study assessed the benefits and adverse effects of combining pharmacological and non-pharmacological methods in hypotension prophylaxis.

Methods

This randomised controlled trial was conducted at Cairo University Hospital's obstetric theatre from January to October 2020. The study included 85 parturients who were randomised to two groups. Group Sitting was left seated for 2 min after injection, and Group Control was made to lie down in the supine position immediately after the subarachnoid block. Both groups received prophylactic intravenous norepinephrine infusion, in addition to an ondansetron bolus, before surgery. Patients' systolic blood pressure (SBP) from intrathecal injection until delivery of the foetus, was documented.

Results

The Sitting group's SBP (122 (14) mmHg) till delivery was statistically higher than the Control group's readings (114 (10) mmHg) (P = 0.004). The Sitting group's intraoperative SBP values were often greater than the Control group values. In addition, the Sitting group had a reduced hypotension incidence and a lower rate of ephedrine use than the other group, but bradycardia incidence was comparable between both groups.

Conclusion

In elective caesarean delivery, combining pharmacological and non-pharmacological methods achieve better results regarding maternal hypotension, vasopressor consumption, nausea and vomiting, and foetal outcomes.

THE EFFECTS OF PATIENT POSITION ON EARLY COMPLICATIONS OF SPINAL ANESTHESIA INDUCTION IN ARTHROSCOPIC KNEE SURGERY

Spinal anesthesia is widely used in different patient positions to create efficient and rapid anesthesia induction in surgical interventions. Early and late complications of spinal anesthesia may vary according to the type of needle, drug dose and concentration, patient weight and height, puncture technique, and position of the patient. This study aimed to prospectively compare early complications of spinal anesthesia between patients in sitting and lateral decubitus positions with motor block onset time and sensory block time to T10 level. Spinal anesthesia was performed in 100 ASA I-II patients aged 18-65 years (group S=48; and group L=52) undergoing arthroscopic knee surgery. Hemodynamic data, early complications, sensory and motor block onset times were recorded. Systolic, diastolic and mean arterial pressures were significantly lower in lateral decubitus position as compared to sitting position after spinal anesthesia induction. Arterial blood pressure values decreased significantly in lateral decubitus position as compared with sitting position. Motor block onset time and sensory block onset time were shorter in lateral decubitus position than in sitting position. Accordingly, sitting position could be suggested during induction of spinal anesthesia because it was associated with less pronounced decrease in blood pressures.

Investigation into spinal anesthetic failure with hyperbaric bupivacaine: the role of cold exposure on bupivacaine degradation

PURPOSE

Hyperbaric bupivacaine (0.75% in dextrose) is used for spinal obstetric anesthesia. Occasional clusters of anesthetic failures occur in this setting, not readily attributable to clinical factors. We hypothesized that cold temperature exposure is related to bupivacaine instability.

METHODS

An electronic survey was distributed to Canadian anesthesiologists to determine consistencies in spinal anesthesia practice, and to invite submission of failed bupivacaine samples for analysis. Another survey for hospital pharmacists focused on bupivacaine logistics. Ultraviolet (UV) spectrometry, differential scanning calorimetry, and high performance liquid chromatography were used to evaluate the effect of temperature on bupivacaine chemical stability. Mass spectrometry (MS) was used to observe bupivacaine and dextrose degradation in laboratory samples of hyperbaric 0.75% bupivacaine in dextrose. Hyperbaric bupivacaine that failed to produce adequate anesthesia in labour and delivery patients was subject to tandem MS/MS analysis on commonly observed ions to look for ion patterns consistent with bupivacaine degradation products and to compare with laboratory samples subjected to cold temperatures.

RESULTS

Canadian obstetric anesthesiologists report similar practices and use hyperbaric bupivacaine for spinal anesthesia. Pharmacists surveyed indicated facility storage at room temperature but variable temperatures during shipping. No standard procedure for failure reporting was identified. Analysis of bupivacaine showed a slight decrease in bupivacaine concentration or UV spectral changes after incubation at temperatures ≤ 4°C. Mass spectrometric analysis of hyperbaric bupivacaine from failed spinal anesthesia cases showed complex and inconsistent patterns of ion formation, and different from the ion patterns observed for cooled vs uncooled bupivacaine solutions. Temperature-related changes were noted for dextrose in cooled samples in which dextrose-related ions were formed.

CONCLUSIONS

Canadian clinical practice and handling of hyperbaric bupivacaine is consistent. Most respondents indicated an interest in a formal reporting and collection process. Cold exposure did not degrade bupivacaine. A complex and possibly inconsistent reaction involving dextrose was identified that requires further analysis of a larger sample size to elucidate the mechanisms.

Comparison of 1- and 2-Minute Sitting Positions Versus Immediately Lying Down on Hemodynamic Variables After Spinal Anesthesia with Hyperbaric Bupivacaine in Elective Cesarean Section

BACKGROUND

Hypotension is one of the most common complications of spinal anesthesia in parturients undergoing cesarean section. In this regard, the patient's position may affect the incidence of hypotension.

OBJECTIVES

In this clinical trial, we evaluated the effects of 1- and 2-minute sitting positions versus immediately lying down after spinal anesthesia on hypotension and vasopressor requirements.

METHODS

A total of 72 parturients, scheduled for cesarean section under spinal anesthesia, were randomly divided into 3 groups (24 subjects per group). Groups S1 and S2 remained in a sitting position for 1 and 2 minutes after the induction of spinal anesthesia, respectively, while group T was immediately placed in a lying position. Systolic, diastolic, and mean arterial blood pressure, as well as heart rate, was recorded at 1, 2, 3, and 5 minutes after anesthesia induction, every 5 minutes during the first 30 minutes of surgery, and then every 10 minutes until the end of surgery. P-value less than 0.05 was considered statistically significant.

RESULTS

The overall frequency of hypotension was 50 (69%) cases during surgery; the reported frequency was higher in group T in comparison with group S2 (P = 0.003). The frequency of hypotension before delivery (the first 5 minutes after spinal anesthesia) was 40 (55%) cases, with a higher frequency reported in group T (20, 83%), compared to groups S1 (12, 50%) and S2 (8, 33%) (P = 0.03 and P = 0.001, respectively). The ephedrine requirement in group T (11.73 ± 7.16 mg) was higher than the other two groups (8.69 ± 7.57 and 7.82±7.95 mg in groups S1 and S2, respectively); nevertheless, the difference was not statistically significant (P = 0.19). Moreover, the difference in time to achieve T6 sensory level was only significant between group T (3.25 ± 1.1 minutes) and group S2 (4.73 ± 1.73 minutes) (P = 0.03).

CONCLUSIONS

The present study showed that 1- or 2-minute sitting position after spinal anesthesia with 2.5 cc of hyperbaric bupivacaine in elective cesarean section results in more hemodynamic stability, compared with immediately lying down.

Head Elevation in Spinal-Epidural Anesthesia Provides Improved Hemodynamics and Appropriate Sensory Block Height at Caesarean Section

PURPOSE

We aimed to determine whether head elevation during combined spinal-epidural anesthesia (CSE) and Caesarean section provided improved hemodynamics and appropriate sensory block height.

MATERIALS AND METHODS

Forty-four parous women undergoing CSE for elective Caesarean section were randomly assigned to one of two groups: right lateral (group L) or right lateral and head elevated (group HE) position, for insertion of the block. Patients were positioned in the supine wedged position (group L) or the left lateral and head elevated position (group HE) until a block height of T5 to light touch was reached. Group HE was then turned to the supine wedged position with maintenance of head elevation until the end of surgery. Hemodynamics, including the incidence of hypotension, ephedrine dose required, and characteristics of the sensory blocks were analyzed.

RESULTS

The incidence of hypotension (16 versus 7, p=0.0035) and the required dose of ephedrine [24 (0-40) versus 0 (0-20), p<0.0001] were greater in group L compared to group HE. In group L, the time to achieve maximal sensory block level (MSBL) was shorter (11.8±5.4 min versus 20.1±6.3 min, p<0.0001) and MSBL was also higher than in group HE [14 (T2) versus 12 (T4), p=0.0015].

CONCLUSION

Head elevation during CSE and Caesarean section is superior to positioning without head elevation in the lateral to supine position, as it is associated with a more gradual onset, appropriate block height, and improved hemodynamics.

Comparison of Maternal and Neonatal Effects of Combined Spinal Epidural Anaesthesia in Either the Sitting or Lateral Position During Elective Cesarean Section

OBJECTIVE

Our goal was to demonstrate which position would be hemodynamically and technically better by comparing the effects of combined spinal epidural (CSE) in the sitting or lateral decubitus position for elective cesarean deliveries on maternal and neonatal parameters and ephedrine requirement.

METHODS

Sixty parturients were randomly assigned into two groups to perform CSE in the sitting (Group I, n=30) or right lateral decubitus position (Group II, n=30) using hyperbaric 10 mg bupivacaine and 20 μg fentanyl. Mean arterial pressure (MAP), heart rate (HR), and characteristics of sensory and motor block were recorded from intrathecal drug administration until the end of surgery. Ephedrine and 1(st) analgesic requirement, number of attempts to perform CSE, incidence of paresthesia during spinal needle insertion, and Apgar scores were recorded.

RESULTS

Ephedrine requirements and HR changes were similar in both groups. However, MAP values at 45 min in Group II were significantly less than in Group I. Maximum sensory block levels in Group II were significantly higher than in Group I. Despite similar motor block recovery times in both groups, regression times of sensory block and 1st analgesic requirement in Group II were significantly longer than in Group I. Incidence of paresthesia due to spinal needle (3.3% versus 20% in Groups I and II, respectively) and number of attempts to perform CSE (26.7% versus 60% in Groups I and II, respectively) were significantly higher in Group II. Apgar scores were similar in both groups.

CONCLUSION

Performing CSE in the sitting position would be safer and easier because higher and earlier onset of sensory block, and a greater number attempts at epidural insertion and paresthesia develop to spinal needle insertion in the right lateral position.

A comparison of the haemodynamic effects of lateral and sitting positions during induction of spinal anaesthesia for caesarean section

BACKGROUND

Hypotension during spinal anaesthesia occurs commonly in parturients. By influencing spread of local anaesthetic, maternal position may affect the speed of onset of sensory block and thus the haemodynamic effects. The aim of this study was to determine whether inducing spinal anaesthesia for caesarean section using plain bupivacaine in the lateral position would result in less hypotension compared with the sitting position.

METHODS

One hundred American Society of Anesthesiologists physical status I and II patients undergoing elective caesarean section were randomised to receive spinal anaesthesia in the lateral position (Group L) or the sitting position (Group S). Using the L3-4 interspace, patients received intrathecal plain bupivacaine, 10mg or 12 mg according to their height, after which they were placed immediately in the supine position with left uterine displacement. Maternal blood pressure was measured every minute for 10 min, every three min for 20 min and 5-minutely thereafter. Hypotension was defined as a fall in systolic blood pressure >20% or a value <90 mmHg.

RESULTS

There was no difference in the lowest recorded systolic blood pressure in Group L (99.2±8.9 mmHg) compared with Group S (95.4±12.3 mmHg, P=0.081). However, the lowest recorded mean arterial pressure was greater in Group L (72.9±11.2 mmHg) than in Group S (68.2±9.6 mmHg; P=0.025). The incidence of hypotension was lower in Group L (17/50, 34%) than in Group S (28/50, 56%; P=0.027). Onset of hypotension was similar between groups.

CONCLUSION

Hypotension occurred less frequently when spinal anaesthesia for caesarean using plain bupivacaine was induced with patients in the lateral compared with the sitting position. Values for the lowest recorded mean arterial pressure were greater but values for the lowest recorded systolic blood pressure were similar for patients in the lateral position group.

Epidural volume extension: a review

Epidural volume extension is a technical modification of the combined spinal epidural block. It involves the epidural injection of normal saline or a small volume of local anaesthetic after an intrathecal injection, aiming to augment the post-spinal sensory level. Although the consequent sensory block augmentation has been adequately documented, the probable factors influencing epidural volume extension and its implications for clinical practice are not well defined. This article reviews published literature relating to the probable factors affecting epidural volume extension, its clinical implications, case reports of its successful clinical application and summarises its unexplored effects.

Combined spinal epidural and epidural volume extension: Interaction of patient position and hyperbaric bupivacaine

BACKGROUND

Previous trials have documented failure of block augmentation with epidural volume extension, when applied after the intrathecal injection of hyperbaric bupivacaine was made in sitting position. However, there is no study comparing the effect of change in patient position during block performance, on the results of epidural volume extension.

MATERIALS AND METHODS

The study was conducted in two parts in American Society of Anesthesiologists physical status I or II parturients scheduled for elective cesarean section under regional anesthesia. In the first part, 28 patients were randomized to one of the two groups, depending on whether epidural volume extension was applied following the block in sitting (group SE) or lateral position (group LE) (n=14 each). In the second part of the study another 28 patients were recruited and randomized to receive the block in sitting (group S) or lateral (group L) position (n=14 each), without epidural volume extension. All patients received combined spinal epidural block using needle-through-needle technique with intrathecal injection of 9 mg hyperbaric bupivacaine (0.5%) and 10 μg fentanyl. Epidural volume extension was performed using 5 ml normal saline in groups SE and LE.

RESULTS

In the first part of the study, the maximum sensory block level was higher in group LE vs. SE (P<0.05). In the second part of the study, no significant difference was seen in the maximum sensory level between group S and group L (P>0.05).

CONCLUSIONS

If epidural volume extension is being applied with intention of rapid extension of sensory block when hyperbaric bupivacaine has been injected intrathecally, the combined spinal epidural block should be performed in lateral position rather than in the sitting position.

Does unilateral hip flexion increase the spinal anaesthetic level during combined spinal-epidural technique?

Needle-through-needle combined spinal–epidural (CSE) may cause significant delay in patient positioning resulting in settling down of spinal anaesthetic and unacceptably low block level. Bilateral hip flexion has been shown to extend the spinal block by flattening lumbar lordosis. However, patients with lower limb fractures cannot flex their injured limb. This study was conducted to find out if unilateral hip flexion could extend the level of spinal anaesthesia following a prolonged CSE technique. Fifty American Society of Anesthesiologists (ASA) I/II males with unilateral femur fracture were randomly allocated to Control or Flexion groups. Needle-through-needle CSE was performed in the sitting position at L2-3 interspace and 2.6 ml 0.5% hyperbaric bupivacaine injected intrathecally. Patients were made supine 4 min after the spinal injection or later if epidural placement took longer. The Control group patients (n=25) lay supine with legs straight, whereas the Flexion group patients (n=25) had their uninjured hip and knee flexed for 5 min. Levels of sensory and motor blocks and time to epidural drug requirement were recorded. There was no significant difference in sensory levels at different time-points; maximum sensory and motor blocks; times to achieve maximum blocks; and time to epidural drug requirement in two groups. However, four patients in the Control group in contrast to none in the Flexion group required epidural drug before start of surgery. Moreover, in the Control group four patients took longer than 30 min to achieve maximum sensory block. To conclude, unilateral hip flexion did not extend the spinal anaesthetic level; however, further studies are required to explore the potential benefits of this technique.

Effects of sitting up for five minutes versus immediately lying down after spinal anesthesia for Cesarean delivery on fluid and ephedrine requirement; a randomized trial

BACKGROUND

Patient position after spinal anesthesia has had variable effects on blood pressure and ephedrine requirements. The aim of this study was to determine the effects that sitting the patient up for five minutes after spinal anesthesia would have on intraoperative fluid and ephedrine requirements.

METHODS

The study included 120 women at term gestation who were scheduled for Cesarean delivery under spinal anesthesia. After anesthetic administration, the women were randomized either to sit up for five minutes then lie down (Group S) or to lie down immediately (Group L) to a tilted supine position. A blinded observer recorded sensory block level, systolic blood pressure, heart rate, ephedrine and fluid requirements, adverse events, and time to motor recovery (modified Bromage score of 2).

RESULTS

Group S had a lower intraoperative sensory block height than Group L [T4 (1) vs T2 (1), respectively; P < 0.001]; Group S also required less ephedrine (8% vs 47%, respectively; P < 0.001), received less fluid [709 (59) mL vs 789 (90) mL, respectively; P < 0.001], and experienced less nausea and vomiting (5% vs 22%, respectively; P = 0.014) and shortness of breath (3% vs 28%, respectively; P < 0.001) intraoperatively. In Group S, the odds of requiring ephedrine were 0.09 compared with 0.89 in Group L (odds ratio 0.10). There were no differences in systolic blood pressure (P = 0.127) or heart rate (P = 0.831) over time between groups. Time to a modified Bromage score of 2 was longer in Group S than in Group L [101 (15) min vs 88 (14) min, respectively; P < 0.001].

CONCLUSIONS

Sitting the patient up for five minutes rather than laying the patient down immediately after spinal anesthesia for Cesarean delivery decreased intraoperative sensory block height, ephedrine and fluid requirements, and intraoperative nausea, vomiting, and shortness of breath without affecting systolic blood pressure or the success of the anesthetic. However, the method resulted in delayed postoperative motor recovery.

Spread of spinal anesthesia in patients having perianal surgery in the jackknife position: effects of baricity of 0.5% bupivacaine and positioning during and after induction of spinal anesthesia

STUDY OBJECTIVE

To compare the influence of baricity and patient positioning during onset of subarachnoid block in patients placed in the prone, jackknife position with head-down tilt of 15 degrees .

DESIGN

Randomized study.

SETTING

Operating room of Tonami General Hospital.

PATIENTS

180 ASA physical I and II patients (134 men and 46 women), aged 18 to 54 years, scheduled for elective perianal surgery.

INTERVENTIONS

Patients were randomly divided into 6 groups (n = 30 each) based on baricity (hyperbaric or isobaric) of 0.5% bupivacaine (5 mg) and duration of the sitting position (two, 5, or 10 min) after injection.

MEASUREMENTS

Sensory block levels were examined by pinprick at 0, 5, 10, 20, and 60 minutes after jackknife positioning. Systolic blood pressure and heart rate were also recorded.

MAIN RESULTS

After jackknife positioning, sensory block levels progressively increased until 15 or 20 minutes in all groups. Regardless of baricity of bupivacaine, sensory block levels were higher at 10 through 60 minutes in the two-minute sitting groups than in the 5-minute or 10-minute sitting groups (P < 0.01 and P < 0.01, respectively), and in the 5-minute sitting groups than in the 10-minute sitting groups (P < 0.05). The mean highest sensory block levels were T5, T9, and T11 in the two-minute, 5-minute, and 10-minute sitting groups, respectively.

CONCLUSION

Patient positioning, not baricity of bupivacaine, significantly affected the cephalad spread of spinal anesthesia, and a 10-minute period in the sitting position limits the maximum cephalad spread to T11.

Single-shot spinal anaesthesia, combined spinal-epidural and epidural volume extension for elective caesarean section: a randomized comparison

BACKGROUND

Single-shot spinal and combined spinal-epidural block, with or without epidural volume extension, can be used for caesarean section. There is no trial comparing their block characteristics and adverse effects under identical conditions.

METHODS

60 ASA I or II parturients with gestational age 37 weeks or more, scheduled for elective caesarean section under regional anaesthesia, were included in the trial. Women were randomized to three groups: group SSS: single-shot spinal; group CSE: combined spinal-epidural; group EVE: epidural volume extension of a combined spinal-epidural. Intrathecal injection was identical in the three groups (0.5% hyperbaric bupivacaine 9 mg with fentanyl 10 microg) and was injected via a 25-gauge pencil-point spinal needle, either as a single-shot spinal or through the spinal needle of the needle-through-needle CSE set. In group EVE, 5 mL of normal saline was injected through the epidural catheter. All blocks were performed with the women sitting. Haemodynamic parameters and block characteristics were assessed.

RESULTS

The onset of maximum sensory and motor block was significantly faster in the SSS group than in the other two. Extent and duration of sensory and motor block and the incidence of adverse effects were similar in the three groups (P>0.05).

CONCLUSIONS

Intrathecal block is similar in extent and duration whether given as a single-shot spinal or a combined spinal-epidural with or without epidural volume extension when performed for elective caesarean section using hyperbaric bupivacaine in the sitting position.

A systematic review of randomized controlled trials that evaluate strategies to avoid epidural vein cannulation during obstetric epidural catheter placement

BACKGROUND

In this systematic review, we evaluated the evidence for seven strategies which have been proposed to minimize the incidence of epidural vein cannulation during lumbar epidural catheter placement in pregnant women.

METHODS

Multiple databases were searched to identify prospective, randomized, controlled trials between December 1966 and October 2007 that evaluated methods to avoid epidural vein cannulation after lumbar epidural catheter placement in pregnant women. Published trials were evaluated using a quality assessment tool, and results were combined to evaluate efficacy to prevent epidural vein cannulation.

RESULTS

Of 90 trials screened, 30 trials were included (n = 12,738 subjects). Five strategies reduce the risk of epidural vein cannulation: the lateral as opposed to sitting position (six trials, mean (sd) quality score = 35% [11%], odds ratio (OR) 0.53 [95% confidence interval (CI) 0.32-0.86]), fluid administered through the epidural needle before catheter insertion (8 trials, quality score 48% [18%], OR 0.49 [95% CI 0.25-0.97]), single rather than multiorifice catheter (5 trials, quality score 30% [6%], OR 0.64 [95% CI 0.45-0.91]), a wire-embedded polyurethane compared with polyamide epidural catheter (1 trial, 31%, plus 4 unscored abstracts, OR 0.14 [95% CI 0.06-0.30]) and catheter insertion depth < or =6 cm (2 trials, 47% [11%], OR 0.27 [95% CI 0.10-0.74]). The paramedian as opposed to midline needle approach and smaller epidural needle or catheter gauges do not reduce the risk of epidural vein cannulation.

CONCLUSION

The risk of intravascular placement of a lumbar epidural catheter in pregnancy may be reduced with the lateral patient position, fluid predistension, a single orifice catheter, a wire-embedded polyurethane epidural catheter and limiting the depth of catheter insertion to 6 cm or less. In general, low manuscript quality weakens the strength of these conclusions.

Local anesthesia: an appropriate technology for simple fistula repair

OBJECTIVES

To assess the efficacy of local infiltrative anesthesia with lidocaine hydrochloride in patients undergoing the surgical repair of a simple vesico-vaginal fistula.

METHODS

The study was carried out with 21 patients undergoing the repair of a simple midvaginal vesico-vaginal fistula. The patients' perception of pain was evaluated intraoperatively.

RESULTS

Most patients indicated that the anesthetic agent provided adequate analgesia, and all fistulas were repaired successfully without postoperative complications.

CONCLUSION

Repairing simple vesico-vaginal fistulas is feasible with a local infiltrative anesthetic.

Combined Spinal Epidural Does Not Cause a Higher Sensory Block than Single Shot Spinal Technique for Cesarean Delivery in Laboring Women

BACKGROUND

The combined spinal epidural (CSE) technique has been shown to result in a higher sensory block than an equivalent single shot spinal (SSS) in women undergoing elective cesarean delivery. We tested whether this is true also in laboring women who may have variable epidural pressures.

METHODS

We randomized 40 ASA I parturients in established labor for cesarean delivery into our double-blind study. Group S (n = 20) intrathecally received 2 mL of 0.5% hyperbaric bupivacaine by SSS and group CS received CSE (n = 20) of an equivalent dose of hyperbaric bupivacaine.

RESULTS

We found that similar maximal sensory blocks were achieved in both groups (group S: median T3 [min-max] T6-1 versus group CS: median T3 [min-max] T4-C7, P = 0.517).

CONCLUSION

As compared with previous reports in nonlaboring parturients, the block characteristics of CSE in our study were indistinguishable from those of SSS in laboring parturients for cesarean delivery.

The Sitting Versus Right Lateral Position During Combined Spinal-Epidural Anesthesia for Cesarean Delivery: Block Characteristics and Severity of Hypotension

In the present study we evaluated whether the sitting position during initiation of small-dose combined spinal-epidural anesthesia (CSE) would induce less hypotension as compared with the lateral position. Sixty women undergoing elective cesarean delivery were randomly assigned to receive a spinal injection consisting of 6.6 mg hyperbaric bupivacaine with sufentanil 3.3 microg in either the lateral or the sitting position. After securing the epidural catheter, patients were turned to a 15 degrees left lateral supine position. Ephedrine 5 mg IV was administered prophylactically and subsequently in case of nausea/vomiting and/or hypotension, defined as a systolic blood pressure less than 95 mm Hg or a 25% decrease from baseline values. Although the incidence of ephedrine supplementation was not different, females in the sitting group required less ephedrine (P = 0.012) and there were fewer problems with identifying the epidural space (P = 0.01). However, more patients in this group required epidural supplementation (35% versus 3%; P = 0.007). In the lateral group, blocks extended more cephalad than with the sitting position (P = 0.014). Apgar scores did not differ, but umbilical artery pH values were significantly higher in patients of the sitting group (7.31 +/- 0.04 versus 7.26 +/- 0.03; P = 0.02). We conclude that performing a CSE technique for cesarean delivery in the sitting position was technically easier and induced less severe hypotension.

A comparison of the lateral, Oxford and sitting positions for performing combined spinal-epidural anaesthesia for elective Caesarean section

One hundred women were randomly allocated to the left lateral, Oxford or sitting position for induction of combined spinal-epidural anaesthesia for Caesarean section using 2.5 ml hyperbaric bupivacaine 0.5% and 10 mug fentanyl. Women in the left lateral were then turned to the right lateral position; women in the Oxford position were turned to the same position on their opposite side; and women in the sitting group were turned to the supine left tilt position. Women remained in these positions until ready for surgery, which was conducted in the supine position with a wedge placed under the right hip. Ephedrine requirements before re-positioning for surgery were less in the sitting position than in the other two positions: median (IQR [range]) doses for the lateral, Oxford and sitting groups were 21 (12-30 [6-48]), 18 (7.5-24 [6-48]) and 12 (6-21 [6-42]) mg, respectively; p = 0.04. Sensory block to touch sensation at the T5 dermatomal level was most quickly achieved in the lateral position with median (IQR [range]) block onset times for the lateral, Oxford and sitting groups of 9 (6-13 [4-30]), 15.5 (9-22 [4-34]) and 14 (9-18[6-36]) min, respectively; p = 0.004. In the Oxford position, more epidural catheters required dosing to achieve a sensory block of T5 before surgery: the number of patients (proportion) bolused in the lateral, Oxford and sitting groups was 1 (3%), 7 (22%) and 1 (3%), respectively; p = 0.01. We did not demonstrate any advantage in using the Oxford position for combined spinal-epidural anaesthesia for elective Caesarean section.

The Effect of Right Versus Left Lateral Decubitus Positions on Induction of Spinal Anesthesia for Cesarean Delivery

Induction of spinal anesthesia for cesarean delivery in the left lateral (LL) decubitus position combined with intraoperative left uterine displacement may result in pooling of local anesthetic onto one side of the body. We studied the effect of the right lateral (RL) and LL decubitus positions during placement of spinal anesthesia on the intrathecal spread of 0.5% hyperbaric bupivacaine plus fentanyl in 60 term parturients. Though all parturients acquired a loss of cold sensation at T4 15 min after intrathecal injection, more parturients in the LL group than in the RL group did so at 5 min (P < 0.05). The maximum levels of sensory blockades, amounts of fluid, vasopressor, and supplementary analgesia used, and the incidence of postoperative complications were similar. We conclude that the two positions can be used equally well when hyperbaric bupivacaine and fentanyl are used in cesarean delivery under spinal anesthesia.

IMPLICATIONS

We conducted a double-blinded randomized trial comparing the spread of spinal anesthesia placed with a parturient in either the right or left lateral position. There was a faster onset in the left lateral group; however, the maximum block heights and the time taken to achieve them were similar in both groups.

Combined spinal epidural anaesthesia for caesarean section: a randomised comparison of Oxford, lateral and sitting positions

Maternal position during induction of intrathecal anaesthesia for caesarean section influences block height and haemodynamic stability. In a randomised study of 90 women presenting for elective caesarean section using combined spinal-epidural anaesthesia, three positions were compared--the Oxford position (group O), the right lateral to supine wedged (group R) and the sitting to supine wedged (group S). Hyperbaric bupivacaine 12.5 mg with fentanyl 12.5 microg was injected intrathecally using a needle-through-needle CSE technique. Intravenous ephedrine 6 mg was given every minute that systolic blood pressure fell below 80% of baseline. Time required for block height to reach T5 as assessed by light touch, was similar in the three groups. There were no significant differences in blood pressure although ephedrine requirements were less in group R. There were no significant differences in the incidence of maternal nausea and vomiting or in neonatal outcome as assessed by Apgar scores and umbilical cord blood gas analysis. Although the study failed to show any significant differences in block height between the groups, no women in group O had a block above T2 compared with three in group R and three in group S.

Effect of delayed supine positioning after induction of spinal anaesthesia for caesarean section

BACKGROUND

The study tested the hypothesis that the incidence of hypotension during spinal anaesthesia for caesarean section is less in parturients who remain in the sitting position for 3 min compared with parturients who are placed in the modified supine position immediately after induction of spinal anesthesia.

METHODS

Spinal anaesthesia was induced with the woman in the sitting position using 2.8 ml hyperbaric bupivacaine 0.5% at the L(3-4) or L(2-3) interspace. Ninety-eight patients scheduled for elective caesarean section under spinal anaesthesia were randomised to assume the supine position on an operating table tilted 10 degrees to the left (modified supine position) immediately after spinal injection (group 0, n=52) or to remain in the sitting position for 3 min before they also assumed the modified supine position (group 3, n=46). Isotonic saline 2-300 ml was given intravenously over 15 min before spinal injection followed by 15 ml/kg over 15-20 min after induction of spinal anaesthesia. If the systolic blood pressure decreased to less than 70% of baseline or to less than 100 mmHg or if there was any complaint of nausea, ephedrine was given in 5 mg boluses intravenously every 2 min.

RESULTS

The blood pressure decreased significantly in both groups following spinal injection (P<0.001). Blood pressure variations over time differed significantly between the two groups (P<0.05). However, the incidence of maternal hypotension before delivery was similar in the two groups. The difference was caused by the time to the blood pressure nadir being significantly shorter in group 0 compared with group 3 (9.1+/-4.5 min vs. 11.7+/-3.7 min, P<0.01). Similar numbers of patients received rescue with ephedrine before delivery: 35 (67%) in group 0 vs. 26 (57%) in group 3 (NS). The mean total dose of ephedrine before delivery was 10.9 mg in group 0 vs. 9.2 mg in group 3 (NS). There were no differences in neonatal outcome between the two groups.

CONCLUSION

At elective caesarean section, a 3-min delay before supine positioning does not influence the incidence of maternal hypotension after induction of spinal anaesthesia in the sitting position with 2.8 ml of bupivacaine 0.5% with 8% dextrose.

The effect of 10 degrees head-up tilt in the right lateral position on the systemic blood pressure after subarachnoid block for Caesarean section

Forty women presenting for elective Caesarean section under spinal anaesthesia were randomly assigned to have anaesthesia induced in the right lateral position either in the horizontal position or with 10 degrees head-up tilt. Hyperbaric bupivacaine 2 ml 0.5% with 0.1 mg of morphine was injected intrathecally before the parturients were placed in the supine position with 15 degrees left lateral tilt. Blood pressure and heart rate were monitored every minute and the sensory level (loss of sharp sensation to pinprick) was monitored every 3 min until clamping of the umbilical cord. Ephedrine 6 mg was given every minute that the systolic blood pressure decreased below 90 mmHg. The mean systolic blood pressure during the first 5 min after induction of spinal anaesthesia was lower in the control group compared to the tilted group (99 mmHg vs. 109 mmHg; p = 0.043). The upper limit of block was higher in the control group compared to the tilted group (p = 0.002). The use of 10 degrees head-up tilt resulted in a reduced incidence of hypotension initially and less extensive sensory block.

Effect of lateral versus supine wedged position on development of spinal blockade and hypotension

Aortocaval compression may not be completely prevented by the supine wedged or tilted positions. It is commonly believed, however, that the unmodified full lateral position after induction of spinal anaesthesia might allow excessive spread of the block. We therefore compared baseline arterial pressures in the supine wedged, sitting, tilted and full lateral positions in 40 women who were about to undergo elective caesarean section. They were then given spinal anaesthesia in the left lateral position and randomised to be turned to the right lateral or the supine wedged position, after which speed of onset and spread of blockade to cold sensation were measured every 2 min for 10 min and mean arterial pressure and ephedrine requirement were recorded every minute for 20 min. Baseline mean arterial pressure was 9 mmHg (95% CI 3 to 14) lower in the left lateral (measured in the upper arm) than in the sitting position; those in the supine wedged and tilted positions were intermediate. Following spinal anaesthesia, hypotension (defined as a reading </=80% of the baseline value in the same position) lasted 2.4 min longer (CI +0.6 to +4.1) in the supine wedged group, but there was no significant difference between the groups in maximum fall or ephedrine requirement. The upper level of block rose more rapidly in the supine wedged than in the lateral group and showed less variability. There is therefore no reason to fear the unmodified lateral group position, which may offer better protection against hypotension.

Clinical case discussion: anesthesia for Cesarean section in a parturient with a large intrathoracic tumour

PURPOSE

To report the anesthetic management of a parturient with a large intrathoracic tumour, presenting for Cesarean section.

CLINICAL FEATURES

A 28-yr-old parturient, gravida 1, presented at 33 weeks gestation with a one month history of increasing cough and dyspnea. A computed tomography scan demonstrated a large mass filling the right hemothorax, causing mediastinal displacement to the left and carinal compression. Both mainstem bronchi were compressed and there was near total obliteration of the lumens of the right lobar bronchi. A decision was taken to expedite delivery to allow for staging and treatment of her disease and Cesarean section was scheduled. She was seen in consultation and prescribed oxygen by nasal prongs, dextromethorphan for cough and ranitidine the evening before and the morning of surgery. A subarachnoid block was performed and a block to the upper thoracic dermatomes was achieved; surgery proceeded uneventfully with the patient's head and upper body elevated about 15 degrees from the supine. The patient was discharged to the medical oncology service for evaluation and treatment.

CONCLUSIONS

Intrathoracic tumours are uncommon in pregnancy. The physiological changes of pregnancy may mask not only the initial presentation but also, even advanced intrathoracic disease. Regional anesthesia is the anesthetic of choice and is rarely contraindicated by maternal condition.

Combined spinal-epidural techniques

The combined spinal-epidural technique has been used increasingly over the last decade. Combined spinal-epidural may achieve rapid onset, profound regional blockade with the facility to modify or prolong the block. A variety of techniques and devices have been proposed. The technique cannot be considered simply as an isolated spinal block followed by an isolated epidural block as combining the techniques may alter each block. This review concentrates on technical and procedural aspects of combined spinal-epidural. Needle-through-needle, separate-needle and combined-needle techniques are described and modifications discussed. Failure rates and causes are reviewed. The problems of performing a spinal block before epidural blockade (potential for unrecognised placement of an epidural catheter, inability to detect paraesthesia during epidural placement, difficulty in testing the epidural, delay in positioning the patient) are described and evaluated. Problems of performing spinal block after epidural blockade (risk of catheter or spinal needle damage) are considered. Mechanisms of modification of spinal blockade by subsequent epidural drug administration are discussed. The review considers choice of technique, needle type, patient positioning and paramedian vs. midline approach. Finally, complications associated with combined spinal-epidural are reviewed.

Oxford positioning technique improves haemodynamic stability and predictability of block height of spinal anaesthesia for elective caesarean section

A novel positioning technique was tested to see whether the unpredictability of block height and haemodynamic instability during spinal anaesthesia for caesarean section could be reduced. In this 'Oxford' position, the woman is placed left lateral with an inflated bag under the shoulder and pillows supporting the head. Following spinal injection the woman is turned to an identical right lateral position. This is maintained until just before incision to minimise aorto-caval compression, when she is placed in the wedged supine position. Sixty women undergoing elective caesarean section were randomised to receive spinal anaesthesia using hyperbaric bupivacaine in either the Oxford (group O), or the sitting position followed immediately by the wedged supine position (group S). Ephedrine 6 mg was given every minute that systolic blood pressure was less than 80% of baseline. In group S, 9/30 women lost pinprick sensation up to T4 at 5 minutes compared with 2/30 in group O (chi2 test, P = 0.04). Block height was more variable in group S than in group O (f test, P = 0.001). Blood pressure decreased by a greater amount initially: group S women required more ephedrine (15.5 +/- 12.9 versus 9.2 +/- 7.7 mg, t test, P = 0.03). Block height with spinal anaesthesia for caesarean section is more predictable and haemodynamically stable if the Oxford position is used whilst anaesthesia develops.

The effects of maternal position during induction of combined spinal-epidural anesthesia for cesarean delivery

Combined spinal-epidural anesthesia (CSE) is a popular technique for cesarean delivery. Regional blocks in obstetrics are often performed with the parturient in the sitting position because the midline may be recognized more easily than in the lateral decubitus position. When conventional spinal anesthesia is performed in the sitting position, the patient is placed supine immediately after drug injection. In contrast, when CSE is performed with the woman sitting, there is a delay in assuming the supine position because of epidural catheter placement, which may affect the incidence of hypotension. Healthy women, at term of pregnancy, about to undergo an elective cesarean section under CSE, were randomly assigned to the sitting or lateral recumbent position for initiation of the block. All parturients were given 1000 mL of lactated Ringer's solution in the 15 min preceding induction and an additional 300-500 mL while the actual block was being performed. On completion of the CSE, they were turned to the supine position with left uterine displacement. A second anesthesiologist, blinded to the woman's position during CSE, evaluated the sensory level of anesthesia, maternal heart rate, blood pressure, oxygen saturation, need for ephedrine, and occurrence of nausea and vomiting. Results are expressed as mean +/- SD. Twelve women were studied in the sitting group and 10 were studied in the lateral recumbent group. The severity and duration of hypotension were greater in those parturients who had CSE induced in the sitting (47%+/-7% and 6+/-3 min, respectively) compared with the lateral recumbent position (32%+/-14% and 3+/-2 min, respectively). Women in the sitting group also required twice as much ephedrine (38+/-18 mg) to correct hypotension compared with the other group (17+/-12 mg). In conclusion, the severity and duration of hypotension were greater when CSE was induced in the sitting compared with the lateral decubitus position.

IMPLICATIONS

We studied the induction of combined spinal-epidural anesthesia (CSE) in the sitting versus lateral recumbent positions in healthy women undergoing a scheduled cesarean delivery. The severity and duration of hypotension were greater when CSE was induced in the sitting position. Thus, the position used for induction of CSE should be among the factors considered when there is greater maternal or fetal risk from hypotension.

Motor power pharmacodynamics of subarachnoid hyperbaric 5% lidocaine in the sitting position

BACKGROUND

Repetitive dynamometric measurement using a plantar flexion power device (PFPD) provides detailed data describing the onset and offset of motor block following spinal administration of lidocaine. The aim of this study was to evaluate administration of two doses of spinal lidocaine in the sitting position to determine whether our dynamometric model produces data consistent with our current understanding of the pharmacokinetics of subarachnoid, hyperbaric, 5% lidocaine.

METHODS

Twenty male patients (54 to 80 yr) undergoing cystoscopy received spinal anaesthesia with either 75 mg (n = 10) or 100 mg of hyperbaric lidocaine 5%, in the sitting position, under standardised conditions. Plantar flexion muscle power was recorded during onset and offset of anaesthesia using a load cell interfaced with a computer (PFPD).

RESULTS

Onset of paralysis following spinal block in the sitting position was rapid and complete with motor power declining exponentially to 5% of preoperative values by 8.5 min in all patients. There was no difference in decay or recovery of plantar flexion motor power data between dosage groups in the sitting position. Measurement using the PFPD shows that onset of motor paralysis is described by an exponential decay and that motor recovery occurs at a fixed rate. Extent of block to cold and pinprick was similar in both dosage groups in the sitting position (median T4).

CONCLUSION

This study shows that in the sitting position, doses less than 75 mg of 5% hyperbaric lidocaine are required to significantly improve ambulatory times.

Maternal position during induction of spinal anaesthesia for caesarean section. A comparison of right lateral and sitting positions

Forty women presenting for elective Caesarean section under spinal anaesthesia were randomly assigned to have anaesthesia induced in either the sitting or right lateral positions; 2.5 ml 0.5% hyperbaric bupivacaine was injected over 10 s before the mother was placed in a supine position with a 20 degree lateral tilt. The onset time and height of the subsequent analgesic and anaesthetic block was measured. It took longer to site spinal needles in the lateral position (240 vs 115 s, p < 0.001). There was a faster onset of sensory block to the sixth thoracic dermatomal level (8 vs 10 min, p < 0.001), in the lateral group, although onset time to T4 was comparable. There was no difference in maximum block height or degree of motor block. Mothers in the lateral group required more ephedrine in the first 10 m after siting the spinal (13.5 vs 10.5 mg, p < 0.05).

Ankylosing spondylitis: lateral approach to spinal anaesthesia for lower limb surgery

We describe three patients with long-standing ankyolsing spondylitis (AS) who underwent lower limb joint surgery under spinal anaesthesia. At preoperative assessment, it was considered that intubation of the trachea was likely to be difficult or impossible and previous general anaesthesia was associated with increased morbidity. Midline approach spinal anaesthesia failed but the lateral approach was successful. Spinal anaesthesia was induced using a 24 gauge Sprotte (Pajunk) needle with 3.5 ml heavy bupivacaine 0.5% at the L3-4 interspace with the patients in the sitting position. This resulted in adequate sensory blockade for the surgical procedure. None of the patients required airway interventions but equipment and aids to secure airway were available.