Cardiac performance during unilateral lumbar spinal block after crystalloid preload

Comparison of epidural, spinal, and saddle block for holmium laser enucleation of prostate (HoLEP): A prospective randomized, comparative study

BACKGROUND

Holmium laser enucleation of the prostate (HoLEP) has become an important treatment modality for benign prostate hypertrophy. The aim of the present study was to compare regional anesthesia methods for HoLEP operation and to determine the optimal technique.

METHODS

Sixty patients with American Society of Anesthesiologists scores of I-III were randomly allocated into 3 groups. Patients in group E received an epidural block with 75 mg of bupivacaine plus 50 μg of fentanyl. In group S, 15 mg of bupivacaine and 50 μg fentanyl were used for spinal anesthesia. In group SA, patients received saddle block with 15 mg of bupivacaine and 50 μg of fentanyl.

RESULTS

Time to T10 dermatome block and to maximal level block were longest in group E (P < .05), and maximal sensorial block level was higher in group E than group SA (P < .05). There was a significant difference in postoperative motor block, but no difference in systolic blood pressure and heart rate.

CONCLUSION

Among 3 techniques, saddle block might be preferable in HoLEP because an adequate sensorial level was achieved with lower motor block and stable hemodynamics.

[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.

Comparison of Intraoperative and Postoperative Effects of Lateral Epidural and Midline Epidural Anaesthesia in Patients Undergoing Unilateral Lower Extremity Operation

OBJECTIVE

We aimed to compare lateral and midline epidural anaesthesia using a levobupivacaine-fentanyl combination in patients undergoing unilateral lower extremity operation for anaesthetic effects and postoperative complications.

METHODS

The study included 40 American Society of Anesthesiologists (ASA) I-II group patients. At the L4-5 space, an epidural catheter was placed in patients in Group 1 by directing the tip of the needle at a 45-degree angle to the operation side and in Group 2 with the needle tip in the cephalad direction. Patients in both groups were administered a combination of 10 mL 0.5% levobupivacaine and 50 μg fentanyl via the epidural catheter. Sensorial and motor block levels during the perioperative and postoperative periods and postoperative complications were recorded.

RESULTS

The maximum level of sensory block on the operated side was found to be at the T10 (T8-T10) level in both groups, while the level of sensory block on the non-operated side was at the L2 (L3-T10) level in Group 1, and at the T10 (T8-T10) level in Group 2 (p=0.000). The motor block was more intense on the non-operated side in Group 2 than in Group 1. The postoperative motor block ended earlier in Group 1. The incidence of complication development was similar between the groups.

CONCLUSION

With a shorter lasting and lower level sensorial and motor block, lateral epidural anaesthesia may be a more advantageous method than midline epidural anaesthesia.

Co-loading or pre-loading for prevention of hypotension after spinal anaesthesia! a therapeutic dilemma

Neuraxial blockade such as spinal anaesthesia can cause severe hypotension due to pharmacological sympathectomy resulting in potential deleterious consequences for the patient. Prevention of this spinal anaesthesia induced hypotension is of utmost importance especially in pregnant population as the life of mother as well as fetus is at risk. Several techniques and methodologies have been adopted for the prevention of this neuraxial hypotension with varying degree of success. The administration of intravenous fluids to optimize the blood volume during sympathectomy has been the most popular and widely used as the first line of therapy among these techniques. The intravenous fluids can be used both before and during the administration of spinal anaesthesia, the techniques appropriately named as pre-loading and co-loading respectively. Numerous research studies and available literary evidence suggests that both of these techniques can be equally effective in prevention of hypotension. The use of colloids has been observed to be more effective for pre-loading due to their longer half-life in the intravascular compartment. However, it has also been suggested that no technique is efficient in preventing the hypotension alone and has to be coupled with judicious use of vasopressors.

Thoracic spinal anesthesia is safe for patients undergoing abdominal cancer surgery

AIM

A double-blinded randomized controlled study to compare discharge time and patient satisfaction between two groups of patients submitted to open surgeries for abdominal malignancies using segmental thoracic spinal or general anesthesia.

BACKGROUND

Open surgeries for abdominal malignancy are usually done under general anesthesia, but many patients with major medical problems sometimes can't tolerate such anesthesia. Regional anesthesia namely segmental thoracic spinal anesthesia may be beneficial in such patients.

MATERIALS AND METHODS

A total of 60 patients classified according to American Society of Anesthesiology (ASA) as class II or III undergoing surgeries for abdominal malignancy, like colonic or gastric carcinoma, divided into two groups, 30 patients each. Group G, received general anesthesia, Group S received a segmental (T9-T10 injection) thoracic spinal anesthesia with intrathecal injection of 2 ml of hyperbaric bupivacaine 0.5% (10 mg) and 20 ug fentanyl citrate. Intraoperative monitoring, postoperative pain, complications, recovery time, and patient satisfaction at follow-up were compared between the two groups.

RESULTS

Spinal anesthesia was performed easily in all 30 patients, although two patients complained of paraesthesiae, which responded to slight needle withdrawal. No patient required conversion to general anesthesia, six patients required midazolam for anxiety and six patients required phenylephrine and atropine for hypotension and bradycardia, recovery was uneventful and without sequelae. The two groups were comparable with respect to gender, age, weight, height, body mass index, ASA classification, preoperative oxygen saturation and preoperative respiratory rate and operative time.

CONCLUSION

This preliminary study has shown that segmental thoracic spinal anesthesia can be used successfully and effectively for open surgeries for abdominal malignancies by experienced anesthetists. It showed shorter postanesthesia care unit stay, better postoperative pain relief and patient satisfaction than general anesthesia.

The effect of Trendelenburg position, lactated Ringer's solution and 6% hydroxyethyl starch solution on cardiac output after spinal anesthesia

BACKGROUND

The aim of our study was to evaluate the effects of Trendelenburg position, infusion of 6% hydroxyetyl starch solution or lactated Ringer's solution on changes in cardiac output (CO) after spinal anesthesia in patients older than 50 yr.

METHODS

Seventy patients scheduled for lower extremity orthopedic surgery under spinal anesthesia were allocated randomly to one of the three treatment groups. In the Trendelenburg group, the patients were placed in the Trendelenburg position immediately after the spinal block for 10 min. In the hydroxyethyl starch group and the lactated Ringer's group, the patients received an infusion of 500 mL of 6% hydroxyethyl starch solution or 1000 mL of lactated Ringer's solution over 20 min after the spinal block. CO was measured continuously from 15 min before until 30 min after spinal anesthesia using the impedance cardiography method and arterial blood pressure with an automated device. P < 0.05 was considered statistically significant.

RESULTS

The differences among treatment groups in CO were not statistically significant. Differences in the CO changes from baseline over time were significant. In the Trendelenburg group, CO did not change while the patient was in the Trendelenburg position. In the hydroxyethyl starch group, CO increased significantly after the block and remained significantly increased until the end of measurements. In the lactated Ringer's group, CO increased significantly 10 and 20 min after the block but, after stopping the infusion, CO started to decrease.

CONCLUSIONS

Our study demonstrated that a decrease in CO after spinal anesthesia is prevented by placing the patient in the Trendelenburg position, or infusion of either lactated Ringer's solution or 6% hydroxyetyl starch solution. Although the effects of the infusion of the lactated Ringer's solution are transient, the effects of the infusion of 6% hydroxyethyl starch solution are extended beyond the time the infusion.

Comparison of Hyperbaric Ropivacaine and Hyperbaric Bupivacaine in Unilateral Spinal Anaesthesia

BACKGROUND

To evaluate the clinical efficacy and safety of unilateral spinal anaesthesia with 0.66% hyperbaric ropivacaine compared with 0.5% hyperbaric bupivacaine for arthroscopic knee surgery.

PATIENTS AND METHODS

Forty patients with American Society of Anesthesiology physical status grade I-II were randomly and double blindly allocated to one of two groups. Spinal anaesthesia was performed from the L3-4 or L4-5 interspace with the patient in the lateral decubitus position and with the operative side below. Group B (n = 20) received 7.5 mg of 0.5% hyperbaric bupivacaine and group R (n = 20) received 10 mg of 0.66% hyperbaric ropivacaine. Patients stayed in the lateral decubitus position for 10 minutes and were then turned to the supine position. The characteristics of spinal block, intraoperative quality of spinal anaesthesia, adverse effects and recovery times were recorded.

RESULTS

The onset of sensory block and motor block were significantly earlier in group B compared with group R (p < 0.05). The duration of sensory block and motor block were significantly shorter for group R compared with group B (p < 0.05). Bilateral sensory block occurred in 85% of patients in group B and in 40% of patients in group R (p < 0.05). Bilateral motor block occurred in 70% of patients in group B and in 25% of patients in group R (p < 0.05).

CONCLUSION

For outpatient knee arthroscopy, 10 mg of 0.66% hyperbaric ropivacaine is preferred to 7.5 mg of 0.5% hyperbaric bupivacaine because it provides a more selective unilateral block and a faster recovery.

A Prospective, Randomized Evaluation of the Effects of Epidural Needle Rotation on the Distribution of Epidural Block

We evaluated the effects of turning the tip of the Tuohy needle 45 degrees toward the operative side before threading the epidural catheter (45 degrees -rotation group, n = 24) as compared to a conventional insertion technique with the tip of the Tuohy needle oriented at 90 degrees cephalad (control group, n = 24) on the distribution of 10 mL of 0.75% ropivacaine with 10 microg sufentanil in 48 patients undergoing total hip replacement. The catheter was introduced 3 to 4 cm beyond the tip of the Tuohy needle. A blinded observer recorded sensory and motor blocks on both sides, quality of analgesia, and volumes of local anesthetic used during the first 48 h of patient-controlled epidural analgesia. Readiness to surgery required 21 +/- 6 min in the control group and 17 +/- 7 min in the 45 degree-rotation group (P > 0.50). The maximum sensory level reached on the operative side was T10 (T10-7) in the control group and T9 (T10-6) in the 45 degree-rotation group (P > 0.50); whereas the maximum sensory level reached on the nonoperative side was T10 (T12-9) in the control group and L3 (L5-T12) in the 45 degree-rotation group (P = 0.0005). Complete motor blockade of the operative limb was achieved earlier in the 45 degree-rotation than in the control group, and motor block of the nonoperative side was more intense in patients in the control group. Two-segment regression of sensory level on the surgical side was similar in the two groups, but occurred earlier on the nonoperative side in the 45 degree-rotation group (94 +/- 70 min) than in the control group (178 +/- 40 min) (P = 0.0005). Postoperative analgesia was similar in the 2 groups, but the 45 degree-rotation group consumed less local anesthetic (242 +/- 35 mL) than the control group (297 +/- 60 mL) (P = 0.0005). We conclude that the rotation of the Tuohy introducer needle 45 degrees toward the operative side before threading the epidural catheter provides a preferential distribution of sensory and motor block toward the operative side, reducing the volume of local anesthetic solution required to maintain postoperative analgesia.

IMPLICATIONS

Turning the Tuohy introducer needle 45 degrees toward the operative side before threading the epidural catheter is a simple maneuver that produces a preferential distribution of epidural anesthesia and analgesia toward the operative side, minimizing the volume of local anesthetic required to provide adequate pain relief after total hip arthroplasty.

The timing of intravenous crystalloid administration and incidence of cardiovascular side effects during spinal anesthesia: the results from a randomized controlled trial

We conducted a randomized clinical trial to evaluate the efficacy of crystalloids in preventing spinal-induced hypotension (SIH) and cardiovascular side effects (CVSE) in a group of surgical patients. Participants were assigned to receive lactated Ringer's solution at 1-2 mL/min (Placebo group, n = 142); lactated Ringer's at 20 mL/kg starting 20 min before spinal block (n = 130); or lactated Ringer's at 20 mL/kg starting at the time of spinal block (n = 132). SIH was defined as a decrease of > or = 30% in baseline systolic blood pressure, and CVSE as SIH plus nausea, vomiting, or faintness requiring treatment. The incidence of SIH was similar in all treatment groups. Compared to placebo, crystalloid administration at the time of spinal block resulted in a significant reduction in the proportion of patients developing CVSE from 9.9% to 2.3%. The corresponding relative proportion was 0.23 (95% confidence interval, 0.07-0.78; P = 0.019), and one additional case of CVSE was avoided for each 13 patients receiving crystalloids at the time of spinal block instead of placebo. Administration of crystalloids at the time of spinal block seems to be effective because it provides additional intravascular fluids during the period of highest risk of CVSE after spinal anesthesia.

IMPLICATIONS

Crystalloids are frequently administered to nonobstetric patients minutes before spinal anesthesia to prevent cardiovascular side effects (CVSE). This randomized controlled trial shows that although crystalloids administered before spinal block result in no clinical benefit, they significantly reduce the risk of CVSE when administered at the time of spinal block.

The effects of lactated Ringer's solution infusion on cardiac output changes after spinal anesthesia

We evaluated the effects of an infusion of lactated Ringer's (LR) solution on changes in cardiac output (CO) after spinal anesthesia. Seventy-five patients scheduled for lower extremity surgery under spinal anesthesia were studied. We measured CO (impedance cardiography method) and blood pressure for 25 min before and 30 min after spinal anesthesia. Patients were randomly assigned to three groups. In the No Infusion group, no LR solution was given during the period of measurements. The LR Before group received 12 mL/kg of LR solution within 20 min before spinal anesthesia. The LR After group received 12 mL/kg of LR solution within 20 min starting immediately after spinal anesthesia. After spinal anesthesia, CO decreased by 13.9% in the No Infusion group. In the LR Before group, CO increased after the infusion by 20% and returned to baseline value 30 min after spinal anesthesia. In the LR After group, CO increased after spinal anesthesia, and 30 min after spinal anesthesia, CO was 11.3% above baseline. We conclude that the decrease in CO after spinal anesthesia can be prevented by the infusion of an LR solution, with CO reaching the highest value while the infusion is running.

IMPLICATIONS

We studied the effects of lactated Ringer's solution infusion on cardiac output changes after spinal anesthesia. If the patients received no infusion, cardiac output decreased after spinal anesthesia. However, if the patients received lactated Ringer's solution infusion, cardiac output was maintained.

The comparison of hypertonic saline (7.5%) and normal saline (0.9%) for initial fluid administration before spinal anesthesia

Hypertonic saline can be used for initial fluid administration before spinal anesthesia. It is effective in small-volume fluid resuscitation. This randomized double-blinded study compared the effects of 7.5% hypertonic saline (HS) and 0.9% normal saline (NS) in doses containing 2 mmol/kg of sodium in 40 ASA physical status I-II patients undergoing arthroscopy or other lower limb surgery under spinal anesthesia. We infused 1.6 mL/kg of HS or 13 mL/kg of NS for initial fluid administration before spinal anesthesia induced with a 10-mg dose of 0.5% hyperbaric bupivacaine. Etilefrine was administered to maintain mean arterial pressure at > or =80% of its control value. Systolic and diastolic blood pressure, heart rate, and cardiac index did not differ between the groups, and the amount of etilefrine administered was similar in the treatment groups. In all our patients, the plasma sodium concentrations were within the normal range after surgery and serum osmolality was within the normal range after spinal anesthesia. The time and the volume of the first micturition were similar in both groups, despite the much smaller amount of infused free water in the HS group. We conclude that 7.5% HS was as good as NS for the initial fluid administration before spinal anesthesia when the amount of sodium was kept unchanged.

The influence of left lateral position on cardiac output changes after head up tilt measured by impedance cardiography

BACKGROUND

The value of the impedance cardiography (IC) method for measuring cardiac output (CO) with the subject in the left lateral position has not yet been established. We compared the CO after a 30 degrees head-up tilt with the subjects in the supine and left lateral position.

METHODS

Thirty healthy young volunteers were placed in the supine horizontal position. CO, stroke volume (SV) and heart rate (HR) were measured for five minutes using impedance cardiography (NCOMM3, BoMed Medical Manufacturing, Location). Then a 30 degrees head-up tilt was done and the measurements were continued for an additional five minutes. After that the subjects were placed in the left lateral horizontal position and the measuring procedure was repeated.

RESULTS

After the tilt, SV and cardiac index (CI) decreased and HR increased statistically significantly in the supine and in the left lateral position. SV and CI also decreased statistically significantly but HR did not change after the shift from the supine to the left lateral position. Although CI was smaller in the left lateral position, the time course of CI change after the tilt was identical in the supine and in the left lateral position.

CONCLUSION

When using the IC method of SV measurement, the absolute value of the CI changes when moving from the supine to lateral positions. It is not clear whether this change is physiologic or an artifact of the measurement technique. However, changes in CI in response to a 30 degree head up tilt are the same in either position. We conclude that changes in CI can be measured with the IC method in the lateral position.

Unilateral spinal anaesthesia: gadget or tool?

The results of different studies investigating the use of unilateral spinal anaesthesia are confusing and partly inconsistent. Some authors doubt whether it is possible to create a strictly unilateral block (i.e. motor, sensory and sympathetic) at all, while others claim that such a procedure is standard, especially for ambulatory anaesthesia. This review considers those factors which are relevant, plausible and proven.

Low dose hyperbaric bupivacaine for unilateral spinal anaesthesia

PURPOSE

To evaluate the effects of hyperbaric bupivacaine concentration in producing unilateral spinal anaesthesia.

METHODS

With Ethical Committee approval and written consent, 60 patients undergoing lower limb surgery were placed in the lateral position with the side to be operated on dependent. After dural puncture (25-gauge Whitacre spinal needle), the needle hole was turned toward the dependent side and patients were randomly assigned to receive 8 mg of either 0.5% (Group0.5%, n = 30) or 1% (Group1%, n = 30) hyperbaric bupivacaine. The lateral position was maintained for 15 min, while a blinded observer recorded loss of pinprick sensation and degree of motor block on both sides until two segment regression of sensory level on the dependent side.

RESULTS

At the end of the 15 min lateral position spinal anaesthesia was more frequently unilateral in Group0.5% (80%) than in Group1% (53%)(P < 0.05). However, 30 min after patients were turned supine, unilateral spinal anaesthesia decreased to 60% of cases in Group0.5% and 40% of cases in Group1% (P = NS). The maximum sensory level on the dependent side [T10(L1-T2) in Group0.5% and T8 (T12-T3) in Group1%], time to reach it [20 (5-30) min in Group0.5% and 25 (10-35) min in Group1%], and time to two segment regression of sensory level [80 (30-135) min in Group0.5% and 75 (20-135) min in Group1%] were similar in both groups.

CONCLUSION

Highly concentrated solutions of hyperbaric bupivacaine are not advantageous in obtaining a unilateral spinal anaesthesia, when a small anaesthetic dose is injected slowly through a Whitacre spinal needle.

Effects of spinal needle type on lateral distribution of 0.5% hyperbaric bupivacaine

To evaluate the influence of needle type on the lateral distribution of 0.5% hyperbaric bupivacaine, 30 patients undergoing lower limb surgery were placed in the lateral position with the side to be operated on dependent and underwent dural puncture by either a 25-gauge Whitacre (n = 15) or a 25-gauge Quincke (n = 15) spinal needle. The needle hole was turned toward the dependent side and 8 mg of 0.5% hyperbaric bupivacaine was injected over 30 s. The lateral position was maintained for 15 min while a blind observer recorded loss of pinprick sensation and degree of motor block on both the dependent and nondependent sides every 5 min until regression of motor block by 1 degree on the dependent side. Thirty minutes after the patients were placed in the supine position, unilateral sensory block was observed in 10 patients in the Whitacre group (66%) and in 2 patients in the Quincke group (13%) (P < 0.05). No differences in the rate of unilateral motor block were observed (73% and 40% in Whitacre and Quincke groups, respectively). We conclude that when a small dose of 0.5% hyperbaric bupivacaine is injected slowly into patients in the lateral position for 15 min, the Whitacre spinal needle provides a more marked differential block of sensory nerve roots between dependent and nondependent sides compared with the Quincke needle.

IMPLICATIONS

Because unilateral spinal anesthesia can be advantageous for lower limb surgery, we evaluated the influence of the Whitacre and Quincke spinal needle types on the lateral distribution of small-dose 0.5% hyperbaric bupivacaine injected slowly into adult patients.

Cardiovascular effects of two different regional anaesthetic techniques for unilateral leg surgery

BACKGROUND

Cardiovascular function was assessed in 20 ASA I-II patients, scheduled for elective orthopaedic surgery with tourniquet in order to compare the haemodynamic changes induced by unilateral spinal anaesthesia and combined sciatico-femoral nerve block.

METHODS

After baseline measurement of cardiovascular parameters, patients were randomized to receive unilateral spinal anaesthesia or combined sciatico-femoral nerve block. Spinal anaesthesia was obtained by 8 mg of hyperbaric bupivacaine 0.5% slowly injected (speed=0.02 ml s[-1]) through a 25-G Whitacre spinal needle with the bevel orientated towards the dependent side and patients lying on their operated side for 15 min (group S, n=10). Combined sciatico-femoral nerve block was obtained by 7 mg kg(-1) of mepivacaine 2% (group NB, n=10). Haemodynamic variables were recorded 5, 10, 15, and 30 min after anaesthetic injection before surgery was started.

RESULTS

Anthropometric data, duration of surgery and acceptability of anaesthetic techniques were similar in the 2 groups. In 8 patients of group S, spinal block was restricted to the operated side (pinprick test and Bromage scale), while the other 2 patients developed bilateral spinal block after being turned supine. NB patients showed no haemodynamic changes during the study, whereas patients in group S showed a small but significant decrease of mean arterial blood pressure (P<0.002 vs baseline and P<0.04 vs NB), cardiac index (P<0.01 vs baseline and P<0.01 vs NB), and stroke volume index (P<0.01 vs baseline and P<0.01 vs NB).

CONCLUSION

Both sciatico-femoral and unilateral spinal blockade provide adequate anaesthesia for unilateral leg surgery with tourniquet. The former technique affects cardiovascular performance less than the latter one.