Unilateral spinal anaesthesia with hyperbaric bupivacaine

Implementation of a rapid recovery protocol in total knee arthroplasty. A randomized controlled trial

BACKGROUND

Rapid recovery (RP) in total knee arthroplasty may increase the functionality while reducing costs. The aim of this study is to prove the benefits of a rapid recovery program compared to our classic protocol.

PATIENTS AND METHODS

We performed a RCT (NCT03823573) in patients undergoing otal knee arthroplasty. Intervention group (RP protocol) received local infiltration of levo-bupivacaine in the periarticular tissue and supervized ambulation 4-6h after surgery. Control (C) group received a femoral nerve block with levo-bupivacaine, while a drain was used. Ambulation after its removal. All the patients completed an Oxford Knee Score prior to surgery and 6 months after discharge. An ecodoppler to assess the presence of deep vein thrombosis was made one month after discharge. Minimum follow-up was of 6 months.

RESULTS

A total of 175 patients were included in the trial (92 patients in the control group, 83 patients in the RP group). There were no differences in sex, age, implanted prosthesis, hemoglobin drop, need for transfusion, range of motion on discharge (C: 82.6°, RP: 85°) and at the end of the follow-up (C: 105.1, RP: 106.6), Oxford Knee Score improvement (C: 17.5 points; RP: 19.3 points), patient satisfaction or re-admissions at the emergency department (C: 7.6%; RP: 10.8%). Significancy was found on time of ischemia (C: 81.29min; RP: 85.35min; P=0.03), need for morphine shots (C: 19.7%; RP: 38.6%; P=0.007), hospital stay (C: 3.84 days; RP: 2.54 days, P<0.0001) and time until ambulation (C: 2.46 days; RP: 0.23 days; P<0.0001).

CONCLUSION

Rapid recovery protocols can reduce hospital stay without increasing complications or need for re-admission.

Effect of spinal flexion and extension in the lateral decubitus position on the unilaterality of spinal anesthesia using hyperbaric bupivacaine

Background and Aims:

Many unilateral lower limb orthopedic surgeries are conducted under unilateral spinal anesthesia with full flexion of spine and immediate extension after local anesthetic administration into the subarachnoid space. Studies have shown that extension of the spine in lateral decubitous position makes cauda equina to sink to the dependent side due to gravity. Continuous flexion of the spine causes sunken cauda equina to be suspended in the middle of the subarachnoid space increasing the possibility of unilateralization of the block. Hence, this study was carried out to assess the effect of flexion and extension in lateral decubitus position in unilateral spinal anesthesia.

Material and Methods:

Sixty patients posted for elective unilateral lower limb below knee orthopedic surgeries were randomly allocated into two groups—group F (flexion of spine) and group E (extension of spine). Using a 25-gauge Quincke spinal needle, 8 mg of 0.5% hyperbaric bupivacaine was injected over a period of 80 s at L3–L4 interspace. Patients were kept in flexion or extension according to the group they belong to after drug administration. After 15 min of lateral position in either group, patients were turned to supine position. Sensory blockade was assessed by loss of pinprick sensation and motor blockade by modified Bromage scale.

Results:

Strict unilateral sensory block at 15^th min was in 18 patients in flexion group compared with 11 patients in extension group which is statistically significant (p=0.03). At 60^th min, there was no significant sensory unilaterality between the groups (p=0.06). A strict unilateral motor blockade at 15^th min was also in 18 patients in group F and 11 patients in group E which was also statistically significant (p=0.04). At 60^th min, seven patients in group F and three patients in group E had strict unilateral motor blockade which was also statistically significant (p=0.03). The maximum sensory level on the nondependent side was T10 in group F and T8 in group E, whereas it was T6 in both the groups on the dependent side. There was no difference in the two-segment regression of the sensory block, duration of sensory and motor blockade, the maximum level of the block, and hemodynamic status between the groups.

Conclusion:

Maintaining flexion of the spinal column for 15 min increases the likelihood of unilateral spinal block compared with extension of the spinal column during lateral decubitus positioning.

Comparison of Efficacy and Safety of Unilateral Spinal Anaesthesia with Sequential Combined Spinal Epidural Anaesthesia for Lower Limb Orthopaedic Surgery

INTRODUCTION

Orthopaedic anaesthesia plan requires customi-zation as per patient's need for safe outcome. Sequential Combined Spinal Epidural Anaesthesia (Sequential CSEA) and Unilateral Single Shot Spinal anaesthesia (Unilateral SA), both have advantages over conventional spinal anaesthesia that they provide longer lasting block with less hypotension.

AIM

To compare safety and efficacy of unilateral spinal anaesthesia with sequential combined spinal epidural anaesthesia for lower limb orthopaedic surgery .

MATERIALS AND METHODS

This prospective randomized study was conducted on sixty ASA I-III patients aged 18- 65 years undergoing lower limb orthopaedic surgeries of approximately two hours duration. Sequential CSE group received spinal with 5 mg of 0.5 hyperbaric bupivacaine followed by incremental epidural top up of 2 cc of 0.5% isobaric bupivacaine to achieve and maintain T10 level. In unilateral SA group, unilateral spinal anaesthesia was given with 10 mg of 0.5% hyperbaric bupivacaine. Haemodynamic parameter, anaesthesia readiness time and block characteristics were recorded and results were analysed using unpaired Student's t-test.

RESULTS

There was no failure of block, surgical anaesthesia with T10 sensory level and bromage score three motor block was achieved by all patients in both groups. Anaesthesia readiness time was less in unilateral SA (p<0.001) Incidences of hypotension (p-value 0.0059) and mean ephedrine dose were significantly less in sequential CSEA. Five patients of unilateral SA required supplementation with general anaesthesia.

CONCLUSION

Thus, our study concludes that unilateral SA is a cost-effective and rapidly performed anaesthetic technique. Unilateral SA with 10 mg bupivacaine and sequential CSEA with 5 mg spinal and incremental epidural top up, both provide good quality sensory and motor block for lower limb orthopaedic surgery but sequential CSEA provides significantly more stable haemodynamics with feasibility to prolong block. Thus sequential CSEA should be preferred over unilateral SA in high risk patients especially for major lower limb orthopaedic surgeries.

[Unilateral spinal anesthesia : Literature review and recommendations]

Unilateral spinal anesthesia is a cost-effective and rapidly performed anesthetic technique. An exclusively unilateral block only affects the sensory, motor and sympathetic functions on one side of the body and offers the advantages of a spinal block without the typical adverse side effects seen with a bilateral block. The lack of hypotension, in particular, makes unilateral spinal anesthesia suitable for patients with cardiovascular risk factors e. g. aortic valve stenosis or coronary artery disease. Increasing numbers of surgical procedures are now being performed on an outpatient basis. Until now, spinal anesthesia has been considered unsuitable for this, not only because of the high incidence of intraoperative hypotension and postoperative urinary retention but also because of the prolonged postoperative stay before home discharge. This is not the case with unilateral spinal anesthesia: motor function returns rapidly, the incidence of urinary retention is extremely low, and patients are usually eligible for home discharge sooner than after bilateral spinal anesthesia or general anesthesia. The success of the technique depends on a number of factors. In addition to the local anesthetic, its concentration and dose, and the baricity of the injected solution, the shape of the spinal needle, the injection speed, the patient's position during injection, and the time the patient remains in this position after injection are equally important parameters. A number of intrathecally applied adjuvant drugs are used to give a more intense and/or longer-lasting block. For this review, we collated the published data on unilateral spinal anesthesia from journals with an impact factor greater than 1.0 and defined an optimized method for performing the technique. In order to achieve an exclusively unilateral block one should use 0.5 % hyperbaric bupivacaine injected at a rate of 0.33 ml/min or slower. During the injection and the following 20 min the patient should lie in the lateral decubitus position on the side intended for surgery with knees drawn to the chest. An injection of 5 mg (1 ml) hyperbaric bupivacaine 0.5 % provides an hour-long block to T 12, and a dose of 7.5 to 10 mg (1.5-2.0 ml) extends the block to T 6. Adding clonidine (0.5 to 1.0 µg/kg BW) to the injection prolongs the duration of the block to approximately two to three hours. During the 20-minute fixation period, the cephalad spread of the block can be influenced to a certain extent by raising or lowering the head of the table.

Spinal hemianesthesia: Unilateral and posterior

The injection of a non-isobaric local anesthetic should induce a unilateral spinal anesthesia in patients in a lateral decubitus position. The posterior spinal hemianesthesia only be obtained with hypobaric solutions injected in the jackknife position. The most important factors to be considered when performing a spinal hemianesthesia are: type and gauge of the needle, density of the local anesthetic relative to the CSF, position of the patient, speed of administration of the solution, time of stay in position, and dose/concentration/volume of the anesthetic solution. The distance between the spinal roots on the right-left sides and anterior-posterior is, approximately, 10-15 mm. This distance allows performing unilateral spinal anesthesia or posterior spinal anesthesia. The great advantage of obtaining spinal hemianesthesia is the reduction of cardiovascular changes. Likewise, both the dorsal and unilateral sensory block predominates in relation to the motor block. Because of the numerous advantages of producing spinal hemianesthesia, anesthesiologists should apply this technique more often. This review considers the factors which are relevant, plausible and proven to obtain spinal hemianesthesia.

Comparison of the effects and complications of unilateral spinal anesthesia versus standard spinal anesthesia in lower-limb orthopedic surgery

INTRODUCTION

A restricted sympathetic block during spinal anesthesia may minimize hemodynamic changes. This prospective randomized study compared unilateral and bilateral spinal anesthesia with respect to the intra- and postoperative advantages and complications of each technique.

MATERIAL AND METHODS

Spinal anesthesia was induced with 0.5% hyperbaric bupivacaine and a 25-G Quincke needle (Dr. J) in two groups of patients with physical status ASA I-II who had been admitted for orthopedic surgeries. In group A, dural puncture was performed with the patient in a seated position using 2.5 cm(3) of hyperbaric bupivacaine. Each patient was then placed in the supine position. In group B, dural puncture was performed with the patient in the lateral decubitus position with 1.5 cm(3) of hyperbaric bupivacaine. The lower limb was the target limb. The speed of injection was 1 mL/30s, and the duration of time spent in the lateral decubitus position was 20 min.

RESULTS

The demographic data were similar in both groups. The time to the onset of the sensory and motor block was significantly shorter in group A (p=0.00). The duration of motor and sensory block was shorter in group B (p<0.05). The success rate for unilateral spinal anesthesia in group B was 94.45%. In two patients, the spinal block spread to the non-dependent side. The incidence of complications (nausea, headache, and hypotension) was lower in group B (p=0.02).

CONCLUSION

When unilateral spinal anesthesia was performed using a low-dose, low-volume and low-flow injection technique, it provides adequate sensory-motor block and helps to achieve stable hemodynamic parameters during orthopedic surgery on a lower limb. Patients were more satisfied with this technique as opposed to the conventional approach. Furthermore, this technique avoids unnecessary paralysis on the non-operated side.

Lateral injection using a Whitacre needle with patients in the lateral decubitus position maintained for a prolonged time period produces symmetric sensory block

BACKGROUND

The directional flow of injection through a Whitacre needle can be used to modify the level of sensory blockade. We hypothesized that injection of hyperbaric local anesthetic through a Whitacre needle with the bevel oriented laterally can produce a more symmetric sensory block.

METHODS

Patients scheduled for lower limb surgery under spinal anesthesia with the patient in lateral decubitus position were randomized to receive 10 mg, 0.5% hyperbaric bupivacaine with the Whitacre needle orifice in 1 of 2 orientations, cephalad and lateral. The patient's position was maintained for 15 min after the injection, and sensory blocks were recorded. The primary outcome was the sensory levels between the dependent and nondependent side. The Wilcoxon-Mann-Whitney U-test odds was used to compare unpaired nonparametric data. For the paired samples, 95% confidence intervals (CI) of differences between group medians were calculated using the Hodges-Lehman estimator for the median difference in number of blocked segments.

RESULTS

There was no significant difference in block level between dependent and nondependent sides in the lateral group. The Hodges-Lehmann point estimator was 0.5% and 95% CI was 0-2.5, suggesting a more symmetric sensory block in patients in the lateral decubitus position maintained for a sufficient period of time. A significantly lower level of blockade was noticed on the nondependent side compared to the dependent side in the cephalad group. The Hodges-Lehmann point estimator was 2.5 segments and 95% CI was 0.5-5.

CONCLUSIONS

Injection of 10 mg of 0.5% hyperbaric bupivacaine with the bevel of the Whitacre needle oriented laterally produces more symmetric sensory levels of blockade between the dependent and nondependent sides.

Reducing the concentration to 0.4% enantiomeric excess hyperbaric levobupivacaine (s75: r25) provides unilateral spinal anesthesia. Study with different volumes

BACKGROUND AND OBJECTIVES

Unilateral spinal anesthesia may be obtained with hypobaric or hyperbaric solution. The objective of this study was to compare different doses of enantiomeric excess hyperbaric levobupivacaine to achieve unilateral spinal anesthesia.

METHOD

One hundred and twenty patients were randomized to receive 4 mg, 6 mg or 8 mg of 0.4% enantiomeric excess levobupivacaine. The solutions were administered at the L3-L4, with the patient in a lateral position and kept at this position according to dose administration for 5, 10 or 15 minutes. Sensory block (pinprick) and motor block (scale 0-3) were compared between the operated and contralateral sides.

RESULTS

The onset of analgesia was rapid and comparable between groups. Sensory block was significantly higher in the operated than in nonoperated limb at all times of evaluation. Increasing the dose by 1 mL (2mg) corresponded to an increase of two segments in the mode for the operated side. In the operated side, motor block (MB = 3) of patients occurred in 31 (77.5%) with 4 mg, 38 (95%) with 6 mg, and 40 (100%) with 8 mg. There was a positive correlation between increased dose, blockade duration, and hypotension. All patients were satisfied with the technique used.

CONCLUSIONS

Spinal anesthesia with different volumes of enantiomeric excess hyperbaric bupivacaine (S75: R25) provided a 78% incidence of unilateral spinal block, with the smallest dose used (4 mg) the most efficient.

Ropivacaine for unilateral spinal anesthesia; hyperbaric or hypobaric?

BACKGROUND AND OBJECTIVES

The aim of this study was to compare the unilaterality of subarachnoid block achieved with hyperbaric and hypobaric ropivacaine.

METHODS

The prospective, randomized trial was conducted in an orthopedics surgical suite. In all, 60 ASA I-III patients scheduled for elective total knee arthroplasty were included in the study. Group Hypo (n=30) received 11.25mg of ropivacaine (7.5mg.mL(-1)) + 2mL of distilled water (density at room temperature was 0.997) and group Hyper (n=30) received 11.25mg of ropivacaine (7.5mg.mL(-1)) + 2mL (5mg.mL(-1)) of dextrose (density at room temperature was 1,015). Patients in the hyperbaric group were positioned with the operated side down and in the 15° Fowler position, versus those in the hypobaric group with the operated side facing up and in the 15° Trendelenburg position. Combined spinal epidural anesthesia was performed midline at the L(3-4) lumbar interspace. Hemodynamic and spinal block parameters, regression time, success of unilateral spinal anesthesia, patient comfort, surgical comfort, surgeon comfort, first analgesic requirement time, and adverse effects were assessed.

RESULTS

Time to reach the T10 dermatome level on the operated side was shorter in group Hyper (612.00±163.29s) than in group Hypo (763.63±208.35s) (p<0.05). Time to 2-segment regression of the sensory block level on both the operated and non-operated sides was shorter in group Hypo than in group Hyper.

CONCLUSION

Both hyperbaric and hypobaric ropivacaine (11.25mg) provided adequate and dependable anesthesia for total knee replacement surgery, with a high level of patient and surgeon comfort. Hypobaric local anesthetic solutions provide a high level of unilateral anesthesia, with rapid recovery of both sensory and motor block, and therefore may be preferable in outpatient settings.

Comparative study between combined sciatic-femoral nerve block, via a single skin injection, and spinal block anesthesia for unilateral surgery of the lower limb

BACKGROUND AND OBJECTIVES

Unilateral spinal anesthesia has advantages when used in outpatient basis. The objective of the present study was to compare unilateral spinal anesthesia with combined sciatic-femoral nerve block in unilateral orthopedic surgeries in outpatients.

METHODS

Sixty patients were randomly divided into two groups of 30 patients to receive 6 mg of hyperbaric or hypobaric bupivacaine (RQ group) in left lateral decubitus, or 800 mg of 1.6% lidocaine with epinephrine on sciatic and femoral nerves (CFI group) in dorsal decubitus. A 150-mm needle connected to a neurostimulator, inserted in the middle point between both classical approaches, was used for the nerve block, with the injection of 15 mL on the femoral nerve and 35 mL on the sciatic nerve. The time for the blockades and their duration were evaluated. After twenty minutes, patients were evaluated regarding the sensorial and motor blockades.

RESULTS

Time for performance of spinal anesthesia was substantially lower than for combined sciatic-femoral nerve block. Unilateral blockade was achieved in 90% of the patients in the RQ group, and 100% in the CFI group. Bradycardia or hypotension was not observed.

CONCLUSIONS

This study concluded that combined sciatic-femoral nerve block is technically easy to perform and it can be an alternative for unilateral blockade of the lower limbs. Unilateral spinal anesthesia with low doses of bupivacaine resulted in shorter time to perform it, lower number of attempts, and earlier recovery than combined sciatic-femoral nerve block, but with the same efficacy.

A comparison of low dose hyperbaric levobupivacaine and hypobaric levobupivacaine in unilateral spinal anaesthesia

The aim of this study was to compare the clinical effects and characteristics of hyperbaric and hypobaric levobupivacaine for unilateral spinal anaesthesia. Sixty patients were randomly allocated into two groups to receive either 7.5 mg (1.5 ml) hyperbaric levobupivacaine 0.5% or 7.5 mg (4 ml) hypobaric levobupivacaine 0.1875% for elective arthroscopic surgery of the knee under spinal anaesthesia. The level and duration of sensory block, intensity and duration of motor block were recorded. Unilateral sensory block was observed in 27 patients (90%) in the hyperbaric group and 24 patients (80%) in the hypobaric group in the lateral position. After 15 minutes, patients were turned to supine to redistribute the spinal block toward the non-operative side, but spinal anaesthesia was still unilateral in 18 patients (60%) in the hyperbaric group and 10 patients (33%) in the hypobaric group (P = 0.038). Time to readiness for home discharge and complete recovery of sensory block were similar in both groups. In the hyperbaric group, the motor block scores were higher on the operative side during first 10 minutes than they were in the hypobaric group (P < 0.002). Motor block regression was faster in the hyperbaric group (P = 0.01). Hyperbaric and hypobaric levobupivacaine both provided satisfactory unilateral spinal anaesthesia with good haemodynamic stability for arthroscopic surgery, but with more frequent unilateral spinal anaesthesia in the hyperbaric group.

A Randomised, Double-blind Comparison of Three Different Volumes of Hypobaric Intrathecal Bupivacaine for Orthopaedic Surgery

This study was designed to evaluate different doses of hypobaric 0.15% bupivacaine administered to achieve unilateral orthopaedic surgery under subarachnoid block.

Using a randomised, double-blinded protocol, 150 ASA I to II patients scheduled for elective unilateral orthopaedic surgery were allocated to received a subarachnoid block with hypobaric bupivacaine 0.15% 4.5 mg (3 ml) (Group 1), 6.0 mg (4 ml) (Group 2) or 7.5 mg (5 ml) (Group 3). Measurements included cardiovascular and haemodynamic stability, incidence of unilateral anaesthesia, time to recover from motor block, postoperative urinary retention, transitory neurological symptoms and postdural puncture headache.

There was a dose-dependent increase in the duration of the block, from 1:55±00:20 hours (4.5 mg) to 2:15±00:22 hours (6.0 mg) and 3:15±00:31 hours (7.5 mg). The sensory block in the operated limb was significantly higher than that in the non-operated limb at all times. The increasing dose resulted in an increase of the motor block score. Seventy percent of patients had unilateral block. It was concluded that the spinal anaesthesia in all groups was suitable for single limb orthopaedic surgery. The smallest dose (4.5 mg) of hypobaric 0.15% bupivacaine resulted in more unilateral blocks, with narrower distribution and shorter duration.

Low-dose bupivacaine spinal anaesthesia for percutaneous nephrolithotomy: the suitability and impact of adding intrathecal fentanyl

BACKGROUND

Unilateral spinal anaesthesia has been used for lower limb surgery with a stable cardiovascular state and a short recovery unit stay. We sought to test the suitability of low-dose bupivacaine spinal anaesthesia for percutaneous nephrolithotomy, a procedure hitherto performed under general anaesthesia. Furthermore, we hypothesized that adding intrathecal fentanyl to bupivacaine may improve the quality of anaesthesia.

METHODS

We randomly allocated, through computer-generated randomization, 108 patients subjected to percutaneous nephrolithotomy to receive either 7.5 mg of hyperbaric bupivacaine 5 mg/ml alone or with the addition of 10 microg of fentanyl. Drugs were given at the L(2)-L(3) interspace with the patient in the lateral decubitus position. The patients remained in this position for 10 min, after which the sensory and motor blocks were assessed. Intra-operative analgesic supplementation, when deemed necessary, was achieved with intravenous fentanyl boluses (25 microg).

RESULTS

The sensory and motor blocks after intrathecal bupivacaine and bupivacaine-fentanyl were similar. Sensory block, in both groups, reached the fifth and eighth thoracic dermatomes on the operative and non-operative sides, respectively. Deep motor block occurred on the operative side in all patients and in nearly 50% of patients on the non-operative side. The patients in the bupivacaine-fentanyl group required less intra-operative and post-operative analgesics, and both patients and endoscopists were better satisfied.

CONCLUSION

This study demonstrated, for the first time, that intrathecal low-dose bupivacaine and fentanyl offers a reliable neuraxial block for patients subjected to percutaneous nephrolithotomy, with stable haemodynamics, good post-operative analgesia and acceptable patient and endoscopist satisfaction.

Role of patient posture during puncture on successful unilateral spinal anaesthesia in outpatient lower abdominal surgery

BACKGROUND AND OBJECTIVE

Unilateral spinal anaesthesia is a useful anaesthesia technique in lower abdominal surgery, especially in an outpatient setting. Patient posture is pivotal in the achievement of unilateral anaesthesia. Nevertheless, no studies have elucidated the influence of patient posture during the anaesthetic injection on unilaterality. Thus, the aim was to compare the effect of patient posture, during the induction phase of spinal anaesthesia, on block characteristics.

METHODS

Eighty patients, ASA I-II, scheduled for unilateral hernioplasty were randomized into two groups. Anaesthesia was performed in lateral position in Group 1 (G1) with operative side down and in sitting position in Group 2 (G2) whose patients were then immediately turned on their lateral side. All patients were maintained for 20 min in lateral position with their operative side down. Hyperbaric bupivacaine 1% 10 mg were used.

RESULTS

Unilateral anaesthesia was seen in 80% (32/40) and 12.5% (5/40) of G1 and G2, respectively. The readiness for surgery was faster in G1 (P < 0.0001). The motor block in the non-operative side was stronger in G2 (P < 0.0001). The offset of sensory block was faster in G1 (P = 0.0001). The offset of motor block was slower in G1 (P = 0.0008). The time for voiding was shorter in G1, although not significant.

CONCLUSIONS

Lateral posture during the induction of spinal anaesthesia is pivotal for a higher success of unilateral block, a fast readiness to surgery, and a fast recovery. Therefore, this technique can be considered feasible and time-saving for lower abdominal surgery.

Bilateral vs. unilateral spinal anesthesia for outpatient knee arthroscopies

This prospective randomized study compared unilateral and bilateral spinal anesthesia with respect to intraoperative and postoperative complications, and time to discharge from hospital for knee arthroscopies in outpatients. We studied 70 ASA I patients scheduled for elective outpatient knee arthroscopy. The patients were randomly allocated into two groups to receive either 3 ml (15 mg) 0.5% hyperbaric bupivacaine (bilateral group) or 1.5 ml (7.5 mg) 0.5% hyperbaric bupivacaine (unilateral group). The duration of motor and sensory block and the time to discharge from the hospital were all recorded. Perioperative complications such as hypotension, bradycardia, nausea, vomiting, urinary retention, if present, were recorded. The patients were interviewed by telephone 7 days later, and each patient was asked about headache or backache. The duration of motor and sensory block, and the time to discharge from hospital was shorter in the unilateral group than in the bilateral group. Three patients in the bilateral group were treated for hypotension. Bradycardia occurred in two patients in the bilateral group, and three patients required temporary bladder catheterization due to delay in recovery of spontaneous urination. Nausea and vomiting occurred in three patients in bilateral group. Nine patients in the bilateral group and six patients in the unilateral group developed postspinal headache. Backache occurred in five patients in the bilateral group and in six patients in the unilateral group. Our data indicate that the use of unilateral spinal block is a suitable technique for knee arthroscopies in outpatients.

Intrathecal anesthesia

PURPOSE OF REVIEW

Development of new drugs and special techniques, as well as changes in health care organization have markedly influenced the use of spinal block and its indications. The present review overviews recent developments in local anesthetic drugs, side effects and special techniques for intrathecal anesthesia.

RECENT FINDINGS

Severe complications after spinal anesthesia are acceptably rare. The cardiovascular effects associated with sympathetic block are more frequent but may successfully be treated with volume expansion and administration of vasoactive drugs while the multimodal approach to prevention of such side effects can also reduce the incidence. Based on recent magnetic resonance imaging studies the volume of cerebrospinal fluid at the lumbosacral level is the main determinant of the effects produced by intrathecal injection of local anesthetic solutions. Unfortunately, it is not possible to estimate the volume of cerebrospinal fluid at the lumbosacral region in clinical practice, but it is clear that the total dose of local anesthetic injected into the subarachnoid space is the primary determinant of both therapeutic and unwanted effects of spinal anesthesia. There is overwhelming evidence of the potential risk for neurological dysfunction associated with spinal lidocaine. This evidence is even more relevant in outpatients, in whom lidocaine is primarily indicated. On the other hand, several studies have demonstrated the efficacy and safety of using small doses of long-acting agents, such as bupivacaine or ropivacaine, to produce a short spinal block. The addition of small doses of opioids further helps to minimize the dose of local anesthetic solution required, without affecting the recovery profile from spinal block. The extensive use of pencil-point designs for spinal needles, and the availability of needles of very small size have allowed a significant reduction in the incidence of postdural puncture headache.

SUMMARY

The changes in health care organization observed during the past few years have forced us to change the indications for and clinical uses of intrathecal anesthesia techniques in accordance with the changing needs of surgery. The development of new drugs and special techniques for spinal anesthesia will further improve the clinical use of this old but trusted technique.