Influence of a Tourniquet on Opioid Consumption After Local Infiltration Analgesia for Total Knee Arthroplasty.

OBJECTIVE: Local infiltration analgesia (LIA) with ropivacaine is increasingly used to provide postoperative analgesia after total knee arthroplasty (TKA). TKA may be performed with or without the use of a tourniquet. The absence of local blood flow when infiltrating local anaesthesia below an inflated tourniquet may affect the rate of systemic absorption, and this may have an effect on the duration and intensity of analgesia as compared with LIA without the use of a tourniquet. The aim of the present study was to investigate the influence of tourniquet use during surgery on the time to first request (TTFR) of opioids and opioid consumption. METHODS: Two historical time-based cohorts (one with and one without tourniquet during surgery) of 300 patients underwent primary TKA under spinal anaesthesia and received LIA to provide postoperative analgesia. The cohorts were compared for TTFR of opioids and opioid consumption. RESULTS: TTFR did not significantly differ between the tourniquet and non-tourniquet groups with a median (25th-75th percentile) of 240 (102-651) and 282 (100-720) min, respectively. The median (25th-75th percentile) oxycodone use was higher in the tourniquet group with 50 (20-90) versus 40 (10-77.5) mg (p=0.01). CONCLUSION: There was no difference in the time to first opioid consumption, suggesting that the presence of an inflated tourniquet during local anaesthetic injection does not alter systemic absorption sufficiently to affect the duration of analgesia. However, the use of a tourniquet was associated with a higher opioid consumption, which is most likely caused by pain resulting from the tourniquet itself.

Pharmacokinetics of 400 mg Locally Infiltrated Ropivacaine After Total Knee Arthroplasty Without Perioperative Tourniquet Use.

BACKGROUND AND OBJECTIVES: Local infiltration analgesia (LIA) with ropivacaine for total knee arthroplasty (TKA) is increasingly used. Despite the high doses of ropivacaine, LIA is considered safe, and this perception is sustained by pharmacokinetic data demonstrating that maximum concentrations of ropivacaine stay well below the toxic threshold in plasma. These pharmacokinetic studies all involve TKA procedures with the use of a tourniquet. Recently, performing TKA without the use of a tourniquet is gaining popularity, but no pharmacokinetic data exist when LIA is administered for TKA without the use of a tourniquet. The purpose of this study was to describe the pharmacokinetic profile of a single-shot ropivacaine (200 mL 0.2%) and 0.75 mg epinephrine (1000 µg/mL) when used for LIA in patients for TKA without a tourniquet. METHODS: In this prospective cohort study, 20 patients treated with LIA for TKA without a tourniquet were studied. Plasma samples were taken at 20, 40, 60, 90, 120, 240, 360, 480, 600, 720, and 1440 minutes after local anesthetic infiltration, in which total and unbound ropivacaine concentrations were determined. RESULTS: Results are given as median (interquartile range [IQR]). Median peak ropivacaine concentration was 1.16 µg/mL (IQR, 0.46); median peak unbound ropivacaine concentration was 0.05 µg/mL (IQR, 0.02). The corresponding times to reach the maximum concentration for total and unbound ropivacaine were 360 (IQR, 240) and 360 (IQR, 360) minutes, respectively. CONCLUSIONS: Although great interindividual variability in ropivacaine concentration was found, both total and unbound maximum serum concentrations remained below the assumed systemic toxic thresholds in all samples. CLINICAL TRIAL REGISTRATION: This study was registered at Netherlands Trial Registry (http://www.trialregister.nl), trial ID NTR6306.

Improving Performance by Monitoring the Success Rate of Peripheral Nerve Blocks.

In our hospital, we introduced a system to measure the collective and individual efficacy of brachial plexus and popliteal nerve blocks with the objective to create transparency as an instrument for monitoring and improvement. Initially, individual results were anonymous, but after 1 year anonymity was lifted within the team of anesthesiologists and results are now discussed quarterly. Collective performance of interscalene, supraclavicular, and popliteal blocks improved significantly over time. Sharing and discussing collective and individual performance has resulted in critical self-appraisal and increased willingness to learn from each other and strengthened the team's ambition for further improvement.

Effect of local anesthetic concentration, dose and volume on the duration of single-injection ultrasound-guided axillary brachial plexus block with mepivacaine: a randomized controlled trial.

BACKGROUND: In what way volume, concentration and dose affect block duration is controversial. The purpose of the present study is to investigate the effect of dose, volume and concentration of mepivacaine on the duration of sensory and motor blockade in ultrasound-guided single shot axillary brachial plexus blockade. METHODS: In this parallel group randomized trial conducted in the Sint Maartenskliniek Nijmegen, 45 adult patients undergoing minor orthopaedic forearm, wrist or hand surgery were randomized to 3 groups. Group A: 20 mL mepivacaine 1.5 %, Group B: 30 mL mepivacaine 1 % and Group C: 30 mL mepivacaine 1.5 %. Randomization was computer-generated, with allocation concealment by opaque sequentially numbered sealed envelopes. Patients and observers were blinded to group allocation. PRIMARY OUTCOME MEASURE: duration of sensory block. RESULTS: Forty-five patients were randomized, four patients were excluded and replaced, and 15 patients in each group were included in the analysis. Mean (95 % CI) sensory and motor block duration was 256 (230-282) and 254 (226-282) minutes in Group A, 226 (209-243) and 220 (200-240) minutes in Group B and 270 (249-291) and 264 (244-284) minutes in Group C. Duration of sensory and motor block duration differed significantly between groups (p = 0.012 and p = 0.016 respectively). Post-hoc analysis showed a significantly reduced sensory and motor block duration in Group B when compared to Group C of 44 min. No local anesthetic systemic toxicity was reported. CONCLUSIONS: When using mepivacaine for axillary brachial plexus block, a higher dose and concentration was associated with a longer duration of sensory and motor blockade, but not a higher volume. TRIAL REGISTRATION: The Netherlands National Trial Register NTR3648 . Registered October 3, 2012.

The effects of adding epinephrine to ropivacaine for popliteal nerve block on the duration of postoperative analgesia: a randomized controlled trial.

BACKGROUND: Duration of peripheral nerve blocks depends on multiple factors. Both technique and type of local anesthetic used, either with or without adjuncts, may result in different duration times of the block. The purpose of the present study was to compare the duration of postoperative analgesia of 30 mL ropivacaine 0.75 % with or without epinephrine for popliteal sciatic nerve block. METHODS: Thirty-eight patients were included to receive ultrasound guided continuous popliteal nerve block with ropivacaine 0.75 % either without (ROPI) or with epinephrine 5 µg/mL (ROPI-EPI) for ankle fusion, subtalar fusion, or a combination of both. The primary outcome parameter was the duration of postoperative analgesia as reflected by the time to first request for postoperative analgesia (TTFR) through the popliteal nerve catheter. Secondary outcome measures included the onset of sensory and motor block and NRS score for pain at rest and during movement. RESULTS: Thirty patients, 15 in each group, were studied. Eight patients were withdrawn because of specific withdrawal criteria described in the protocol and replaced according to their group allocation. Median [interquartile range] TTFR was 463 [300-1197] min and 830 [397-1128] min for the ROPI vs ROPI-EPI group respectively. Hodges Lehman median difference between groups was 71 min (95 % CI -415 - 473 min). There was no difference in any clinical outcome measure between the groups. CONCLUSION: The results of this study did not show any significant increase in the duration of postoperative analgesia by adding epinephrine to ropivacaine for popliteal nerve block. This may be due to the intrinsic vasoconstrictive properties of ropivacaine. The absence of a significant difference can also be the result of a type II error caused by a large variation in the individual TTFR. TRIAL REGISTRATION: Trial register.nl identifier: NTR3330 , keyword TTFR.

No correlation between minimal electrical charge at the tip of the stimulating catheter and the efficacy of the peripheral nerve block catheter for brachial plexus block: a prospective blinded cohort study.

BACKGROUND: Stimulating catheters offer the possibility of delivering an electrical charge via the tip of the catheter. This may be advantageous as it allows verifying if the catheter tip is in close proximity to the target nerve, thereby increasing catheter performance. This prospective blinded cohort study was designed to investigate whether there is a correlation between the minimal electrical charge at the tip of the stimulating catheter, and the efficacy of the peripheral nerve block (PNB) catheter as determined by 24 h postoperative morphine consumption. METHODS: Forty adult patients with ASA physical health classification I-III scheduled for upper extremity surgery under combined continuous interscalene block and general anesthesia were studied. Six patients were excluded from analysis.After inserting a stimulating catheter as if it were a non-stimulating catheter for 2-5 cm through the needle, the minimal electrical charge necessary to obtain an appropriate motor response was determined. A loading dose of 20 mL ropivacaine 0.75% ropivacaine was then administered, and postoperative analgesia was provided by a continuous infusion of ropivacaine 0.2% 8 mL.h-1 via the brachial plexus catheter, and an intravenous morphine patient-controlled analgesia (PCA) device.Main outcome measures include the minimal electrical charge (MEC) at the tip of the stimulating catheter necessary to elicit an appropriate motor response, and the efficacy of the PNB catheter as determined by 24 h postoperative PCA morphine consumption. RESULTS: Mean (SD) [range] MEC at the tip of the stimulating catheter was 589 (1414) [30 - 5000] nC. Mean (SD) [range] 24 h morphine consumption was 8.9 (9.9) [0-29] mg. The correlation between the MEC and 24 h postoperative morphine consumption was Spearman's Rho rs = -0.26, 95% CI -0.56 to 0.09. CONCLUSION: We conclude that there is no proportional relation between MEC at the tip of the blindly inserted stimulating catheter and 24 h postoperative morphine consumption. TRIAL REGISTRATION: Trialregister.nl identifier: NTR2328.

Pharmacokinetics of 450 mg ropivacaine with and without epinephrine for combined femoral and sciatic nerve block in lower extremity surgery. A pilot study.

AIMS: No pharmacokinetic data exist on doses of ropivacaine larger than 300 mg for peripheral nerve block in man, although in clinical practice higher doses are frequently used. The purpose of the present study was to describe the pharmacokinetic profile in serum of 450 mg ropivacaine with and without epinephrine in patients undergoing anterior cruciate ligament reconstruction. METHODS: Twelve patients were randomly allocated to receive a single shot combined sciatic/femoral nerve block with 60 ml of either ropivacaine 0.75% alone (group R, n = 6) or ropivacaine 0.75% plus epinephrine 5 µg ml(-1) (group RE, n = 6). Venous blood samples for total and free ropivacaine serum concentrations were obtained during 48 h following block placement. Pharmacokinetic parameters were calculated using a non-compartmental approach. RESULTS: Results are given as mean (SD) for group R vs. group RE (95% CI of the difference). Total Cmax was 2.81 (0.94) µg ml(-1) vs. 2.16 (0.21) µg ml(-1) (95% CI -0.23, 1.53). tmax was 1.17 (0.30) h vs. 1.67 (0.94) h (95% CI -1.40, 0.40). The highest free ropivacaine concentration per patient was 0.16 (0.08) µg ml(-1) vs. 0.12 (0.04) µg ml(-1) (95% CI -0.04, 0.12). t(1/2) was 6.82 (2.26) h vs. 5.48 (1.69) h (95% CI -1.23, 3.91). AUC was 28.35 (5.92) µg ml(-1) h vs. 29.12 (7.34) µg ml(-1) h (95% CI -9.35, 7.81). CONCLUSIONS: Free serum concentrations of ropivacaine with and without epinephrine remained well below the assumed threshold of 0.56 µg ml(-1) for systemic toxicity. Changes in pharmacokinetics with epinephrine co-administration did not reach statistical significance.

Safety of retransfusing shed blood after local infiltration analgesia in total knee arthroplasty.

We investigated the safety of LIA (local infiltration analgesia) combined with retransfusion of drained blood. Total knee arthroplasty patients received two peri-articular injections during surgery followed by continuous infusion, both with ropivacaine (567 mg). Ropivacaine plasma concentrations were determined in blood samples taken at 0, 3, 6 and 24 hours postoperatively. The collected shed blood was not retransfused, instead retransfusion was modelled by estimating the cumulative plasma concentrations at 6 hours postoperative. Total and unbound ropivacaine plasma concentrations ranged respectively from 0.08 to 1.9 mg/L and 0.003 to 0.11 mg/L. An average of 13.1 +/- 3.7 mg unbound ropivacaine would have been returned to the patient. The estimated cumulative ropivacaine plasma levels showed that instant retransfusion would have led to plasma levels below 0.26 mg/L. It appears to be safe to transfuse autologous blood in combination with LIA. However, before drawing definite conclusions formal measurement of actual concentrations is required.

Effect of local anesthetic volume (15 vs 40 mL) on the duration of ultrasound-guided single shot axillary brachial plexus block: a prospective randomized, observer-blinded trial.

BACKGROUND AND OBJECTIVES: One of the advantages of ultrasound-guided peripheral nerve block is that visualization of local anesthetic spread allows for a reduction in dose. However, little is known about the effect of dose reduction on sensory and motor block duration. The purpose of the present study was to compare the duration of sensory and motor axillary brachial plexus block (ABPB) with 15 or 40 mL mepivacaine 1.5%. METHODS: Thirty patients were randomly allocated to receive ultrasound-guided ABPB with either 15 (group 15 mL, n = 15) or 40 mL (group 40 mL, n = 15) mepivacaine 1.5%. Onset, efficacy, and duration of sensory and motor block were compared. RESULTS: Two patients in group 15 mL needed an additional rescue block before surgery and were excluded from subsequent analysis. The overall median duration of sensory and motor block was significantly shorter in group 15 mL (225 [148-265] mins vs 271 [210-401] mins and 217 [144-250] mins vs 269 [210-401] mins, respectively; P < 0.01). Duration of sensory and motor block of individual nerves was significantly shorter in group 15 mL (20%-40% reduction for sensory and 18%-37% for motor block). Time to first request of postoperative analgesia was also significantly reduced in group 15 mL (163 [SD, 39] vs 235 [SD, 59] mins, respectively, P < 0.05). There were no differences in the other block characteristics. CONCLUSIONS: In ABPB with mepivacaine 1.5%, reducing the dose from 40 mL to 15 mL (62.5%) shortens the overall duration of sensory and motor block by approximately 17% to 19%, reduces sensory and motor block duration of individual nerves by 18% to 40%, and decreases the time to first request of postoperative analgesia by approximately 30%.

The effect of stimulating versus nonstimulating catheter techniques for continuous regional anesthesia: a semiquantitative systematic review.

BACKGROUND AND OBJECTIVES: Stimulating catheters provide feedback regarding the location of the catheter tip in relation to the target nerve or plexus. There is debate concerning whether stimulating catheters may reduce the failure rate of postoperative analgesia or whether they may enhance functional recovery by providing superior and more reliable postoperative analgesia. METHODS: Studies comparing the effect of stimulating versus nonstimulating catheters for postoperative analgesia were systematically and independently searched by 2 authors. RESULTS: Eleven randomized controlled studies could be included in this review. One trial was performed in volunteers; the others were clinical trials in patients. Five trials were performed in patients scheduled for a femoral nerve catheter, 4 for a distal sciatic nerve catheter, 1 in patients receiving an interscalene nerve catheter, and 1 in patients with an infraclavicular brachial plexus block. A standard quantitative analysis was deemed inappropriate because of considerable heterogeneity regarding the investigated outcome parameters. A semiquantitative review revealed that efficacy (judged by reduction in the need for rescue analgesics, complete surgery block, or median effective local anesthetic volume blocking the nerve) suggests improvement in stimulating catheters compared with nonstimulating catheters. Patient satisfaction as well as functional recovery was poorly investigated, so no conclusions could be drawn. CONCLUSIONS: Published reports of randomized controlled trials provide evidence for a better analgesic effect from stimulating catheters. Future trials should be conducted in a standardized manner with uniform reporting of outcomes, which may facilitate future quantitative analysis.

[Paraplegia following a transurethral prostate resection: the anterior spinal artery syndrome]. / Paraplegie na een transurethrale prostaatresectie. Het A.-spinalis-anteriorsyndroom.

A 73-year-old man with an extensive cardiovascular risk profile and history underwent a transurethral resection of the prostate under spinal anaesthesia. The use of acetylsalicylic acid was stopped 10 days before the operation. No anaesthesiological or surgical complications occurred during the operation, but 6 hours after the operation the patient developed severe pain in both legs. Besides the hyperalgesia, there was a paresis and a reduced sensitivity of the legs. The patient had developed anterior spinal artery syndrome due to ischaemia of the lower thoracic myelum. Despite intensive rehabilitation this ultimately resulted in a residual disability and the patient became wheelchair bound. There seems to be a correlation between the patient's comorbidity, the stopping of the thrombocyte aggregation inhibitor and the occurrence of this particularly rare complication.

The effect of a long term epidural infusion of ropivacaine on CYP2D6 activity.

BACKGROUND: Ropivacaine and one of its metabolites, pipecoloxylidide, inhibit CYP2D6 in. human liver microsomes in vitro with K(i) values of 5 microM (1.4 mg/L) and 13 microM (3.6 mg/L), respectively. We investigated the effect of a 50 h continuous epidural infusion of ropivacaine 2 mg/mL at a rate of 14 mL/h on CYP2D6 activity. METHODS: Nineteen patients (41-85 yr) undergoing hip or knee replacement, all extensive metabolizers with respect to CYP2D6 activity, were included. Medications known to inhibit or be metabolized by CYP2D6, or known to be strong inhibitors/inducers of CYP1A2 or CYP3A4 were not allowed. Patients received 10 mg debrisoquine (a marker for CYP2D6 activity) before surgery and after 40 h epidural infusion. The metabolic ratio (MR) for debrisoquine hydroxylation was calculated as the amount of debrisoquine/amount of 4-OH-debrisoquine excreted in 0-10 h urine. RESULTS: The median (range) of MR before and after ropivacaine were 0.54 (0.1-3.4) and 1.79 (0.3-6.7), respectively. The Hodges Lehman estimate of the ratio MR after/MR before ropivacaine was 2.2 with a 95% confidence interval 1.9-2.7 (P < 0.001). CONCLUSION: A continuous epidural infusion of ropivacaine inhibits CYP2D6 activity in patients who are extensive metabolizers resulting in a twofold increase in the MR for debrisoquine hydroxylation. However, since none of the patients was converted into a functional poor metabolizer (MR >12.6), the effect on the metabolism of other drugs metabolized by CYP2D6 is unlikely to be of major clinical importance.

Postoperative epidural analgesia after total knee arthroplasty with sufentanil 1 microg/ml combined with ropivacaine 0.2%, ropivacaine 0.125%, or levobupivacaine 0.125%: a randomized, double-blind comparison.

BACKGROUND AND OBJECTIVES: Total knee replacement is associated with severe postoperative pain that, if treated insufficiently, interferes with early rehabilitation. The purpose of the present study is to compare the efficacy of ropivacaine (0.2% and 0.125%) and levobupivacaine (0.125%), all in combination with sufentanil 1 microg/mL with regard to postoperative pain relief and absence of motor block in a patient-controlled epidural analgesia setting. METHODS: The study design was randomized and double-blind. Sixty-three patients scheduled for total knee replacement under combined spinal-epidural anesthesia were randomly allocated to receive ropivacaine 0.2%/sufentanil 1 microg/mL (group 1), ropivacaine 0.125%/sufentanil 1 microg/mL (group 2), or levobupivacaine 0.125%/sufentanil 1 microg/mL (group 3) for postoperative epidural pain relief. Primary endpoints were numerical rating scores for pain and patient satisfaction, motor block scores, time to first demand of the patient-controlled epidural analgesia device and average hourly consumption of local anesthetic and sufentanil. RESULTS: There were no significant differences between the 3 groups regarding numerical rating scores for pain, patient satisfaction, and motor block scores at any of the time intervals; time to first demand and average hourly sufentanil consumption were similar. Patients in group 1 used significantly more local anesthetic than patients in groups 2 and 3. CONCLUSIONS: All 3 solutions provided adequate analgesia and minimal motor block. The higher concentration of ropivacaine 0.2% was associated with a higher consumption of local anesthetic and did not result in a decrease in the consumption of sufentanil. Under the conditions of this study, patient-controlled epidural analgesia consumption of the epidural mixture was predominantly determined by sufentanil.

Inspired carbon dioxide during hypoxia: effects on task performance and cerebral oxygen saturation.

INTRODUCTION: Exposure to a hypoxic environment has a deleterious effect on physiological and mental functions. We studied the effect of added inspired CO2 during artificially induced hypoxic normobaric hypoxia (oxygen saturation approximately 80%) on complex task performance. METHODS: In random order, 22 healthy volunteers were exposed to 3 gas mixtures for 50 min each: sham hypoxia (SH, PetO2 103 mmHg without inspired CO2); isocapnic hypoxia (IH, PetO2 approximately 40 mmHg, PetcO2 clamped to 0.4 mmHg above resting values); and poikilocapnic hypoxia (PH, PetO2 approximately 40 mmHg; no inspired CO2). Brain oxygenation was measured using near infrared spectroscopy. During minutes 25-45 of hypoxia, subjects performed vigilance and task performance tests used in aviation research: the Vigilance and Tracking test and the Multi-Attribute Task battery (MAT-bat). The tests varied in difficulty with the tracking tests considered most difficult. RESULTS: PetCO2 levels differed significantly among groups: IH 42.8 +/- 0.7, SH 39.0 +/- 0.7, and PH 36.8 +/- 0.7 mmHg. Brain oxygenation levels were significantly higher during IH than PH (62.2 +/- 1.0 vs. 59.1 +/- 1.3%). The results of the performance tests indicated a negative effect of PH vs. SH on most function tests. For the Tracking test of the MAT-bat, performance was worst during PH, but returned to baseline during IH. DISCUSSION: We demonstrate the ability of added inspired CO2 to improve performance during hypoxia by preventing PH-associated hypocapnia-induced vasoconstriction of brain blood vessels. Our results are relevant to aerospace medicine and other circumstances in which complex tasks are performed in a hypoxic environment such as mountain climbing and working in confined spaces.

The effect of age on the systemic absorption and systemic disposition of ropivacaine after epidural administration.

Knowledge about the systemic absorption and disposition of ropivacaine after epidural administration is important in regard to its clinical profile and the risk of systemic toxicity. We investigated the influence of age on the pharmacokinetics of ropivacaine 1.0% after epidural administration, using a stable-isotope method. Twenty-four patients were enrolled in 1 of 3 groups according to age (group 1: 18-40 yr; group 2: 41-60 yr; group 3: > or =61 yr). Patients received 150 mg ropivacaine hydrochloride epidurally. After 25 min, patients received 50 mL 0.44 mg/mL deuterium-labeled ropivacaine (D3-ropivacaine) IV. Arterial blood samples were collected up to 24 h after epidural administration. Total plasma concentrations of ropivacaine and D3-ropivacaine were determined using liquid chromatography mass spectrometry. In the oldest patients, elimination half-life was significantly longer (ratio of the geometric means 0.60; 95% confidence interval, 0.37-0.99) and clearance was significantly decreased (mean difference, 194 mL/min; 95% confidence interval, 18-370 mL/min) compared with the youngest patients. The systemic absorption was biphasic. Absorption kinetics for ropivacaine (fractions absorbed: (F1, F2) and half-lives: (t(1/2),a1), t(1/2),a2) during the fast and slow absorption process: 0.27 +/- 0.08 and 0.77 +/- 0.12, respectively; 10.7 +/- 5.2 min and 248 +/- 64 min, respectively) were in the same range as for other long-acting local anesthetics. F1 was on average 0.11 (95% confidence interval, 0.002-0.22) higher in the youngest compared with the middle age group. Observed age-dependent pharmacokinetic differences do not likely influence the risk of systemic toxicity in the elderly after a single epidural dose of ropivacaine.

The epidural "top-up": predictors of increase of sensory blockade.

BACKGROUND: Extension of sensory blockade after an epidural top-up in combined spinal epidural (CSE) anesthesia is partly attributed to compression of the dural sac by the injected volume. This study investigated whether a volume effect plays a significant role when administering an epidural top-up after an initial epidural loading dose and assessed the predictive value of different factors with respect to the increase in sensory blockade. METHODS: After an epidural loading dose of 75 mg ropivacaine, 0.75%, 30 patients were randomly assigned to one of three groups. After the maximum level of sensory blockade (MLSB) had been established, patients received either an epidural top-up with 10 ml ropivacaine, 0.75% (group 1, n = 10) or saline (group 2, n = 10), or no epidural top-up (group 3, n = 10). Subsequently, sensory blockade was assessed at 5-min intervals for a further 30 min by a blinded observer. RESULTS: The MLSB increased significantly in the patients receiving an epidural top-up with ropivacaine but not in the patients receiving normal saline. Sensory block extension was inversely related to the number of segments blocked at the time of the epidural top-up, and female gender was associated with a smaller increase in MLSB. CONCLUSIONS: When using epidural ropivacaine, the extension of sensory blockade after administering an epidural top-up is caused by a local anesthetic effect and not by a volume effect. Under the conditions of this study, predictors of the increase in sensory blockade are the presence of ropivacaine in the top-up injectate, the number of segments blocked at the time of epidural top-up, and gender.

The effects of age on neural blockade and hemodynamic changes after epidural anesthesia with ropivacaine.

UNLABELLED: We studied the influence of age on the neural blockade and hemodynamic changes after the epidural administration of ropivacaine 1.0% in patients undergoing orthopedic, urological, gynecological, or lower abdominal surgery. Fifty-four patients were enrolled in one of three age groups (Group 1: 18-40 yr; Group 2: 41-60 yr; Group 3: > or=61 yr). After a test dose of 3 mL of prilocaine 1.0% with epinephrine 5 microg/mL, 15 mL of ropivacaine 1.0% was administered epidurally. The level of analgesia and degree of motor blockade were assessed, and hemodynamic variables were recorded at standardized intervals. The upper level of analgesia differed among all groups (medians: Group 1: T8; Group 2: T6; Group 3: T4). Motor blockade was more intense in the oldest compared with the youngest age group. The incidence of bradycardia and hypotension and the maximal decrease in mean arterial blood pressure during the first hour after the epidural injection (median of Group 1: 11 mm Hg; Group 2: 16 mm Hg; Group 3: 29 mm Hg) were more frequent in the oldest age group. We conclude that age influences the clinical profile of ropivacaine 1.0%. The hemodynamic effects in older patients may be caused by the high thoracic spread of analgesia, although a diminished hemodynamic homeostasis may contribute. IMPLICATIONS: Analgesia levels after the epidural administration of 15 mL of ropivacaine 1.0% increase with increasing age. This is associated with an increased incidence of hypotension in the elderly, although an effect of age on the hemodynamic homeostasis may have contributed. It appears that epidural doses should be adjusted for elderly patients.