Comparing the biological washout of ß+-activity induced in mice brain after 12C-ion and proton irradiation.

In clinical ion beam therapy, protons as well as heavier ions such as carbon are used for treatment. For protons, ß(+)-emitters are only induced by fragmentation reactions in the target (target fragmentation), whereas for heavy ions, they are additionally induced by fragmentations of the projectile (further referred to as autoactivation). An approach utilizing these processes for treatment verification, by comparing measured Positron Emission Tomography (PET) data to predictions from Monte Carlo simulations, has already been clinically implemented. For an accurate simulation, it is important to consider the biological washout of ß(+)-emitters due to vital functions. To date, mathematical expressions for washout have mainly been determined by using radioactive beams of (10)C- and (11)C-ions, both ß(+)-emitters, to enhance the counting statistics in the irradiated area. Still, the question of how the choice of projectile (autoactivating or non-autoactivating) influences the washout coefficients, has not been addressed. In this context, an experiment was carried out at the Heidelberg Ion Beam Therapy Center with the purpose of directly comparing irradiation-induced biological washout coefficients in mice for protons and (12)C-ions. To this aim, mice were irradiated in the brain region with protons and (12)C-ions and measured after irradiation with a PET/CT scanner (Siemens Biograph mCT). After an appropriate waiting time, the mice were sacrificed, then irradiated and measured again under similar conditions. The resulting data were processed and fitted numerically to deduce the main washout parameters. Despite the very low PET counting statistics, a consistent difference could be identified between (12)C-ion and proton irradiated mice, with the (12)C data being described best by a two component fit with a combined medium and slow washout fraction of 0.50 ± 0.05 and the proton mice data being described best by a one component fit with only one (slow) washout fraction of 0.73 ± 0.06.

Whole-genome assemblies of 56 burkholderia species.

Burkholderia is a genus of betaproteobacteria that includes three notable human pathogens: B. cepacia, B. pseudomallei, and B. mallei. While B. pseudomallei and B. mallei are considered potential biowarfare agents, B. cepacia infections are largely limited to cystic fibrosis patients. Here, we present 56 Burkholderia genomes from 8 distinct species.

Automation and uncertainty analysis of a method for in-vivo range verification in particle therapy.

We introduce the automation of the range difference calculation deduced from particle-irradiation induced ß(+)-activity distributions with the so-called most-likely-shift approach, and evaluate its reliability via the monitoring of algorithm- and patient-specific uncertainty factors. The calculation of the range deviation is based on the minimization of the absolute profile differences in the distal part of two activity depth profiles shifted against each other. Depending on the workflow of positron emission tomography (PET)-based range verification, the two profiles under evaluation can correspond to measured and simulated distributions, or only measured data from different treatment sessions. In comparison to previous work, the proposed approach includes an automated identification of the distal region of interest for each pair of PET depth profiles and under consideration of the planned dose distribution, resulting in the optimal shift distance. Moreover, it introduces an estimate of uncertainty associated to the identified shift, which is then used as weighting factor to 'red flag' problematic large range differences. Furthermore, additional patient-specific uncertainty factors are calculated using available computed tomography (CT) data to support the range analysis. The performance of the new method for in-vivo treatment verification in the clinical routine is investigated with in-room PET images for proton therapy as well as with offline PET images for proton and carbon ion therapy. The comparison between measured PET activity distributions and predictions obtained by Monte Carlo simulations or measurements from previous treatment fractions is performed. For this purpose, a total of 15 patient datasets were analyzed, which were acquired at Massachusetts General Hospital and Heidelberg Ion-Beam Therapy Center with in-room PET and offline PET/CT scanners, respectively. Calculated range differences between the compared activity distributions are reported in a 2D map in beam-eye-view. In comparison to previously proposed approaches, the new most-likely-shift method shows more robust results for assessing in-vivo the range from strongly varying PET distributions caused by differing patient geometry, ion beam species, beam delivery techniques, PET imaging concepts and counting statistics. The additional visualization of the uncertainties and the dedicated weighting strategy contribute to the understanding of the reliability of observed range differences and the complexity in the prediction of activity distributions. The proposed method promises to offer a feasible technique for clinical routine of PET-based range verification.

Integration and evaluation of automated Monte Carlo simulations in the clinical practice of scanned proton and carbon ion beam therapy.

Monte Carlo (MC) simulations of beam interaction and transport in matter are increasingly considered as essential tools to support several aspects of radiation therapy. Despite the vast application of MC to photon therapy and scattered proton therapy, clinical experience in scanned ion beam therapy is still scarce. This is especially the case for ions heavier than protons, which pose additional issues like nuclear fragmentation and varying biological effectiveness. In this work, we present the evaluation of a dedicated framework which has been developed at the Heidelberg Ion Beam Therapy Center to provide automated FLUKA MC simulations of clinical patient treatments with scanned proton and carbon ion beams. Investigations on the number of transported primaries and the dimension of the geometry and scoring grids have been performed for a representative class of patient cases in order to provide recommendations on the simulation settings, showing that recommendations derived from the experience in proton therapy cannot be directly translated to the case of carbon ion beams. The MC results with the optimized settings have been compared to the calculations of the analytical treatment planning system (TPS), showing that regardless of the consistency of the two systems (in terms of beam model in water and range calculation in different materials) relevant differences can be found in dosimetric quantities and range, especially in the case of heterogeneous and deep seated treatment sites depending on the ion beam species and energies, homogeneity of the traversed tissue and size of the treated volume. The analysis of typical TPS speed-up approximations highlighted effects which deserve accurate treatment, in contrast to adequate beam model simplifications for scanned ion beam therapy. In terms of biological dose calculations, the investigation of the mixed field components in realistic anatomical situations confirmed the findings of previous groups so far reported only in homogenous water targets. This work can thus be useful to other centers commencing clinical experience in scanned ion beam therapy.

TPS(PET)-A TPS-based approach for in vivo dose verification with PET in proton therapy.

Since the interest in ion-irradiation for tumour therapy has significantly increased over the last few decades, intensive investigations are performed to improve the accuracy of this form of patient treatment. One major goal is the development of methods for in vivo dose verification. In proton therapy, a PET (positron emission tomography)-based approach measuring the irradiation-induced tissue activation inside the patient has been already clinically implemented. The acquired PET images can be compared to an expectation, derived under the assumption of a correct treatment application, to validate the particle range and the lateral field position in vivo. In the context of this work, TPSPET is introduced as a new approach to predict proton-irradiation induced three-dimensional positron emitter distributions by means of the same algorithms of the clinical treatment planning system (TPS). In order to perform additional activity calculations, reaction-channel-dependent input positron emitter depth distributions are necessary, which are determined from the application of a modified filtering approach to the TPS reference depth dose profiles in water. This paper presents the implementation of TPSPET on the basis of the research treatment planning software treatment planning for particles. The results are validated in phantom and patient studies against Monte Carlo simulations, and compared to ß(+)-emitter distributions obtained from a slightly modified version of the originally proposed one-dimensional filtering approach applied to three-dimensional dose distributions. In contrast to previously introduced methods, TPSPET provides a faster implementation, the results show no sensitivity to lateral field extension and the predicted ß(+)-emitter densities are fully consistent to the planned treatment dose as they are calculated by the same pencil beam algorithms. These findings suggest a large potential of the application of TPSPET for in vivo dose verification in the daily clinical routine.

[Significantly shorter anesthesia time for surgery of the lumbar spine : process analytical comparison of spinal anesthesia and intubation narcosis]. / Signifikant kürzere Anästhesiezeit bei lumbaler Wirbelsäulenchirurgie : Prozessanalytischer Vergleich von Spinalanästhesie und Intubationsnarkose.

INTRODUCTION: Most surgery of the lumbar spine is performed with the patient under general anesthesia (GA); however, qualitative benefits of spinal anesthesia (SA) have been reported. The goal of this study was to compare time efficiency between these two anesthesia methods in lumbar spine surgery. To test the hypothesis that the use of SA leads to significant time saving compared to GA for lumbar spine surgery, key points in the preoperative, intraoperative and postoperative anesthesiology care times were analyzed. The focus was on anesthesia time excluding surgery time. MATERIALS AND METHODS: Electronically based data of 473 anesthesia procedures (368 SA, 105 GA) for lumbar spine interventions performed in the prone position (i. e. decompression, discectomy and transpedicular instrumentation) were analyzed retrospectively. Patient population data including gender, age, American Society of Anesthesiologists (ASA) classification and body mass index (BMI) were analyzed. The focus was on the documented perioperative key time points which are defined as follows: (1) induction, (2) positioning (turning into prone position), (3) scrubbing and covering, (4) surgery time (knife to skin closure), (5) closing (end of surgery until leaving operating room) and (6) handing over to recovery. Differences in the amount of time for each perioperative period were calculated for SA and GA. RESULTS: In 7 out of the 368 SA patients SA failed and had to be converted to GA. There were no significant differences in BMI, ASA prevalence and gender between SA and GA patients but SA patients were significantly older (median 61.7 ± 15.4 years) than GA patients (median 56.1 ± 14.6 years). However, SA required significantly less time for induction (SA: 17.7 ± 7.0 min, GA: 21.6 ± 7.2 min), preoperative preparation (SA: 9.7 ± 3.6 min, GA: 13.3 ± 5.4 min) and closing period (SA: 4.9 ± 1.1 min, GA: 15.3 ± 5.7 min) compared to GA. Total anesthesia time with exclusion of the surgery time revealed a significant time reduction using SA of 19 min (95 % confidence interval: range 13.6-24.4 min, median in SA: 56.7 min, median in GA: 75.7 min, p < 0.0001). CONCLUSIONS: This study showed that in lumbar spine surgery 19 min of anesthesia time can be saved using SA compared to GA which could have an impact on economic aspects. Gender, BMI and ASA had no statistically detectable influence on the choice between the two anesthesia methods. The fact that time-intensive complex instrumentation is mainly performed in younger patients may explain why GA patients were younger than SA patients.

Sensitivity of intravenous and oral alfentanil and pupillary miosis as minimal and noninvasive probes for hepatic and first-pass CYP3A induction.

Systemic and oral clearances of alfentanil (ALF) are in vivo probes for hepatic and first-pass cytochrome P450 (CYP) 3A. Both ALF single-point plasma concentrations and miosis are surrogates for area under the concentration-time curve (AUC) and clearance and are minimal and noninvasive CYP3A probes. This investigation determined ALF sensitivity for detecting graded CYP3A induction and compared it with that of midazolam (MDZ). Twelve volunteers (sequential crossover) received 0, 5, 10, 25, or 75 mg oral rifampin for 5 days. MDZ and ALF were given intravenously and orally on sequential days. Dark-adapted pupil diameter was measured with blood sampling. Graded rifampin decreased plasma MDZ AUCs to 83, 76, 62, and 59% (intravenous (i.v.)) and 78, 66, 39, and 24% (oral) of control. Hepatic and first-pass CYP3A induction were detected comparably by plasma MDZ and ALF AUCs. Single ALF concentrations detected all CYP3A induction, whereas MDZ was less sensitive. ALF miosis detected induction of first-pass but not hepatic CYP3A.

Role of FDG PET/CT in imaging of renal lesions.

Focal incidental renal lesions are commonly encountered on positron emission tomography (PET)/computed tomography (CT) imaging. The vast majority of these lesions are benign. However, the interpretation of renal lesions can be problematic if the imaging criteria of simple cysts are not met. Limited literature exists on the characterisation of renal masses with metabolic imaging. The purpose of this article is to focus on the imaging features of benign and malignant renal masses with PET/CT. The lesions discussed include renal cyst, angiomyolipoma, oncocytoma, renal cell carcinoma, renal metastases and other infiltrating neoplastic processes affecting the kidney. Both the anatomical and metabolic features which characterise these benign and malignant entities are described. We emphasise the importance of viewing the CT component to identify the typical morphological features and discuss how to best use hybrid imaging for management of renal lesions. Metabolic imaging has a promising role in the imaging of renal lesions and can help prevent unnecessary biopsies and ensure optimal management of suspicious lesions.

Hybrid SPECT-CT and PET-CT imaging of differentiated thyroid carcinoma.

Hybrid imaging modalities such as radioiodine single photon emission CT with integrated CT ((131)I SPECT-CT) and 2-(fluorine-18)-fluoro-2-deoxy-D-glucose positron emission tomography with integrated CT (FDG PET-CT) allow the rapid and efficient fusion of functional and anatomic images, and provide diagnostic information that may influence management decisions in patients with differentiated thyroid carcinoma (DTC). Diagnostic localisation and therapy of these tumours are dependent upon their capacity to concentrate radioiodine ((131)I) via uptake through the sodium-iodide symporter and retention within the tumour. The prognosis for most patients with DTC is favourable, although controversy exists regarding the role of post-operative (131)I therapy in patients at low-risk for disease. Accurate identification of functional thyroid tissue (benign or malignant) using diagnostic (131)I planar scintigraphy complemented by SPECT-CT imaging enables the completion of post-operative staging and patient risk stratification prior to (131)I therapy administration. In patients with non-iodine-avid tumours (negative (131)I scan but elevated thyroglobulin indicative of persistent or recurrent disease), FDG PET-CT is used to identify tumours with enhanced glucose metabolism and to localise the source of thyroglobulin production. The CT component of this hybrid technology provides anatomic localisation of activity and allows CT-based attenuation correction of PET images. Images from 15 patients illustrate the applications of (131)I SPECT-CT and FDG PET-CT.

Cannabis improves night vision: a case study of dark adaptometry and scotopic sensitivity in kif smokers of the Rif mountains of northern Morocco.

Previous reports have documented an improvement in night vision among Jamaican fishermen after ingestion of a crude tincture of herbal cannabis, while two members of this group noted that Moroccan fishermen and mountain dwellers observe an analogous improvement after smoking kif, sifted Cannabis sativa mixed with tobacco (Nicotiana rustica). Field-testing of night vision has become possible with a portable device, the LKC Technologies Scotopic Sensitivity Tester-1 (SST-1). This study examines the results of double-blinded graduated THC administration 0-20 mg (as Marinol) versus placebo in one subject on measures of dark adaptometry and scotopic sensitivity. Analogous field studies were performed in Morocco with the SST-1 in three subjects before and after smoking kif. In both test situations, improvements in night vision measures were noted after THC or cannabis. It is believed that this effect is dose-dependent and cannabinoid-mediated at the retinal level. Further testing may assess possible clinical application of these results in retinitis pigmentosa or other conditions.

Risk factors for sudden intrauterine unexplained death: epidemiologic characteristics of singleton cases in Oslo, Norway, 1986-1995.

OBJECTIVE: The epidemiologic characteristics of unexplained stillbirths are largely unknown or unreliable. We define sudden intrauterine unexplained death as a death that occurs antepartum and results in a stillbirth for which there is no explanation despite postmortem examinations, and we present risk factors for this type of stillbirth in singleton gestations. STUDY DESIGN: Singleton antepartum stillbirths (n = 291) and live births (n = 582) in Oslo were included and compared with national data (n = 2025 and n = 575,572, respectively). Explained stillbirths (n = 165) and live births in Oslo served as controls for the cases of sudden intrauterine unexplained death (n = 76) in multiple logistic regression analyses. RESULTS: One fourth of stillbirths remain unexplained. The risk of sudden intrauterine unexplained death (1/1000) increased with gestational age, high maternal age, high cigarette use, low education, and overweight or obesity. Primiparity and previous stillbirths or spontaneous abortions were not associated with sudden intrauterine unexplained death. CONCLUSIONS: Risk factors for sudden intrauterine unexplained death are identifiable by basic antenatal care. Adding unexplored stillbirths to the unexplained ones conceals several risk factors and underlines the necessity of a definition that includes thorough postmortem examinations.

The anesthetic and recovery profile of two doses (60 and 80 mg) of plain mepivacaine for ambulatory spinal anesthesia.

UNLABELLED: Reports of transient neurological symptoms with the use of subarachnoid lidocaine has generated interest in alternate local anesthetics of intermediate duration, such as mepivacaine. This prospective randomized, double-blinded, dose-response study examined the anesthetic and recovery profiles of 60- and 80-mg doses of preservative-free plain mepivacaine for ambulatory spinal anesthesia. Sixty patients undergoing ambulatory anterior cruciate ligament repair of the knee under spinal anesthesia were randomized into two groups; Group 1 (29 patients) received 4 mL of 1.5% (60-mg dose) and Group 2 (31 patients) received 4 mL of 2% (80-mg dose) of plain mepivacaine. All patients received a combined spinal-epidural anesthetic technique. The epidural catheter was used only in the event the surgery outlasted the duration of surgical anesthesia with subarachnoid mepivacaine. Epidural supplementation was administered in three patients (12%) in Group 1 and one patient (3%) in Group 2 when the sensory block regressed to L-1 with surgery expected to last longer than 15 min. The cephalad dermatome level of the block and degree of motor block was comparable in the two groups. Times to two-segment and T-10 regression were comparable in the two groups (112 +/- 26 min in Group 1 versus 122 +/- 28 min in Group 2). Time to L-1 regression was significantly longer in Group 2 (146 +/- 28 min in Group 1 versus 159 +/- 19 min in Group 2). All of the ambulatory milestones were significantly faster in Group 1. Side effects, such as hypotension and emesis were negligible, severe bradycardia and urinary retention did not occur, and none of the patients in the two groups reported transient neurological symptoms over 24 h. In conclusion, plain mepivacaine in a 60- or 80-mg dose is a suitable local anesthetic choice for ambulatory spinal anesthesia with respect to anesthetic, as well as recovery profiles. IMPLICATIONS: We evaluated the anesthetic and recovery profiles of 60- and 80-mg doses of plain mepivacaine for ambulatory spinal anesthesia. Both doses produced comparable sensory and motor block. Sensory and motor regression and ambulatory milestones were 20-30 min longer with the 80-mg dose. Side effects were negligible and transient neurological symptoms were not reported during a 24-h follow-up.

A collaborative regional ocular anesthesia training program: successes and failures.

STUDY OBJECTIVE: To describe a collaborative effort of the departments of ophthalmology and anesthesiology to teach anesthesiology residents regional ocular anesthesia; to detect any differences in positive or negative outcomes after blocks performed by anesthesiology residents versus blocks performed by ophthalmology residents. DESIGN: Prospective descriptive, study. SETTING: Outpatient surgery in a university-affiliated veterans affairs hospital. PATIENTS: 614 patients requiring elective ocular surgery. INTERVENTIONS: Outcomes from patients who underwent regional anesthesia performed by ophthalmology residents were compared to outcomes from patients who received anesthesia from anesthesiology residents. MEASUREMENTS AND MAIN RESULTS: A detailed description of the collaborative teaching program in ocular anesthesia is presented. Ophthalmology residents performed the majority of regional ocular blocks (87% vs. 13%). There was no statistical difference in the incidence of negative outcomes, such as retrobulbar hemorrhage, between ophthalmology residents and anesthesiology residents (3/534 vs. 1/80) or in the incidence of successful blocks (90% for ophthalmology residents vs. 88% for anesthesiology residents). CONCLUSIONS: Regional ocular anesthetic techniques can be safely and successfully taught to residents in anesthesiology.

Propofol versus propofol-ketamine sedation for retrobulbar nerve block: comparison of sedation quality, intraocular pressure changes, and recovery profiles.

UNLABELLED: We compared sedation quality, intraocular pressure (IOP) changes, and recovery profiles in patients who received propofol or propofol-ketamine sedation during placement of the retrobulbar nerve block (RBB). Seventy elderly patients undergoing cataract extraction according to a prospective, randomized, double-blinded protocol were preoperatively evaluated with a Mini-Mental State examination and baseline IOP. A hypnotic dose was provided with either propofol (Group P) or a propofol-ketamine (Group PK) combination. The IOP measurement was repeated, and the surgeon initiated the RBB. Supplemental study drug was given if needed. The level of sedation was considered acceptable if the patient exhibited minimal or no movement and grimacing with needle insertion. Patients were evaluated in terms of quality of sedation, cardiopulmonary stability, and recovery profile. Compared with patients in Group P, patients in Group PK had a significantly faster onset of acceptable sedation (Group P 235 +/- 137 s versus Group PK 164 +/- 67 s) and required significantly less supplemental sedation (Group P 1.1 +/- 1.9 mL versus Group PK 0.15 +/- 0.3 mL). Additionally, none of the Group PK patients required ventilatory assistance, but two patients in Group P required assisted mask ventilation. In conclusion, the addition of ketamine (13.2 +/- 3.3 mg) to propofol (44 +/- 11 mg) decreased the hypnotic requirement and improved the quality of sedation without prolonging recovery. IMPLICATIONS: Anesthesiologists frequently perform retrobulbar blocks while simultaneously providing sedation. Using ketamine to supplement propofol sedation provided a faster onset and improved the quality of sedation during the retrobulbar block procedure.

Striatal dopaminergic abnormalities in human cocaine users.

OBJECTIVE: Previous human postmortem experiments have shown an abnormally high number of dopamine uptake sites in the striatum of chronic cocaine users, which might contribute to cocaine withdrawal symptoms such as depression and suicidality. Previous inconsistencies in results were perhaps related to selective radioligand affinity changes or a coexisting loss of dopamine neurons. METHOD: In the present study, binding of the cocaine analog [3H]WIN 35428 to the dopamine transporter was assayed in postmortem striatal samples from 15 cocaine-using subjects and 15 matched comparison subjects to determine whether there were differences in number of binding sites or in affinity. Binding to the vesicular monoamine transporter, a measure of total dopaminergic terminals, was also assessed by using the radioligand (+)-[3H]dihydrotetrabenazine (DTBZ). RESULTS: Striatal [3H]WIN 35428 binding sites were significantly more numerous in the cocaine users: the mean Bmax value was 9.0 fmol bound/microg protein (SD = 2.8) for the cocaine users but only 6.0 (SD = 1.7) for the comparison subjects. Severity of chronic cocaine use was significantly related to [3H]WIN 35428 binding level. [3H]DTBZ binding was significantly lower in the cocaine users (mean = 330 nCi/mg, SD = 42) than in the comparison subjects (mean = 374, SD = 68). CONCLUSIONS: The present results confirm that cocaine users have a high number of dopamine transporter binding sites on dopaminergic neurons, despite an apparent low number of total dopamine terminals. These abnormalities may contribute to the abnormalities in subjective experience and behavior characteristic of chronic cocaine abusers.

The role of nigrostriatal dopamine in metabotropic glutamate agonist-induced rotation.

Metabotropic glutamate receptors are a major class of excitatory amino acid receptors. Eight metabotropic glutamate receptors subtypes have been cloned and have been classified into three groups based on their amino acid sequence homology, effector systems, and pharmacological profile. Previous results have shown that striatal group I metabotropic glutamate receptor stimulation produces vigorous contralateral rotation in intact rats, thought to be due to increased striatal dopamine release. Examination of FOS-like immunoreactivity and local cerebral glucose metabolism suggests that this occurs secondary to activation of the subthalamic nucleus. We sought to determine the contribution of dopamine by examining metabotropic glutamate receptor agonist-induced rotation in rats following acute dopamine depletion by reserpine/alpha-methyl-para-tyrosine treatment, or chronic dopamine depletion by 6-hydroxydopamine treatment. In unilateral 6-hydroxydopamine lesioned rats, the group I metabotropic glutamate receptor agonist (RS)-3,5-dihydroxyphenylglycine induced contralateral rotation with a coincident increase in striatal 3,4-dihydroxyphenylacetic acid. The rotation was attenuated by the group I antagonist 1-aminoindan-1,5-dicarboxylate. Examination of FOS-like immunoreactivity and [14C]2-deoxyglucose uptake in chronically dopamine depleted rats also revealed similar patterns to those seen previously in intact rats. However, acutely dopamine depleted rats do not exhibit metabotropic glutamate receptor agonist-induced rotation and show a different pattern of [14C]2-deoxyglucose uptake, with no increase in glucose utilization in the intermediate and deep layers of the superior colliculus. These results suggest that there are compensatory changes under conditions of chronic dopamine denervation which permit metabotropic glutamate receptor agonist-induced rotation to occur, which may include dopamine receptor supersensitivity, increased dopamine turnover, and/or changes in sensitivity of striatal group I metabotropic glutamate receptors. The group III metabotropic glutamate receptor agonist L-(+)-2-amino-4-phosphonobutyrate induced contralateral rotation in 6-hydroxydopamine lesioned rats, while it had no effect in intact rats. Additionally, examination of FOS-like immunoreactivity revealed a distinct pattern following L-(+)-2-amino-4-phosphonobutyrate administration in 6-hydroxydopamine lesioned versus intact rats. These results suggest that there is a change in the effect of striatal group III stimulation under conditions of dopamine depletion.

Does the choice of anesthetic technique affect the recovery of bowel function after radical prostatectomy?

OBJECTIVES: Return of bowel function after radical prostatectomy surgery may be the limiting factor in discharging these patients from the hospital. Recent studies have shown that postoperative epidural infusion of bupivacaine decreases time to return of bowel function compared with intravenous and epidural morphine in patients after abdominal surgery. This study focuses on the role of the intraoperative anesthetic technique on recovery of bowel function, intraoperative blood loss, and the incidence of postoperative deep venous thrombosis (DVT) in patients undergoing radical retropubic prostatectomy and pelvic lymphadenectomy. METHODS: Forty patients undergoing prostatectomy were randomized to either group A (general endotracheal anesthesia, including muscle relaxation and mechanical ventilation, followed by postoperative intravenous morphine patient-controlled analgesia) or group B (thoracic epidural anesthesia using bupivacaine, combined with "light" general anesthesia using a laryngeal mask airway and spontaneous ventilation, followed by epidural morphine analgesia). Intra- and postoperative data were collected on blood loss, volumes of crystalloid and colloid infused, blood transfused, duration of anesthesia and surgery, anesthetic and surgical complications, time to recovery of bowel function, quality of postoperative pain control, and time to discharge from hospital. Each patient underwent lower extremity venous ultrasonography to detect DVT. RESULTS: Twenty-one patients received general anesthesia and 19 received combined epidural and general anesthesia. Intraoperative blood loss was significantly lower in the epidural group, and times to first flatus and first bowel movement were also shorter in this group. There were no significant differences in duration of anesthesia or surgery, quality of postoperative analgesia, side effects of analgesia, or time to discharge from hospital. There was no DVT detected in any patient. CONCLUSIONS: The combined anesthetic technique of thoracic epidural anesthesia and "light" general anesthesia with spontaneous ventilation decreased intraoperative blood loss and shortened the time to return of bowel function. However, this earlier return of bowel function was not great enough to realize a difference in time to hospital discharge. There was no evidence of increased complications secondary to epidural anesthesia or of prolonged anesthetic time necessary to place epidural catheters.

The recovery profile of hyperbaric spinal anesthesia with lidocaine, tetracaine, and bupivacaine.

BACKGROUND AND OBJECTIVES: Surgical procedures previously considered too lengthy for the ambulatory surgery setting are now being performed during spinal anesthesia. The complete recovery profile of tetracaine and bupivacaine are now of interest but are not available in the literature. This study was conducted to compare times to ambulation, voiding, and complete block resolution, as well as the incidence of back and radicular pain, after spinal anesthesia with lidocaine, bupivacaine, and tetracaine. METHODS: Twelve adult volunteers underwent spinal anesthesia on three separate occasions with three local anesthetics (lidocaine 100 mg, bupivacaine 15 mg, and tetracaine 15 mg in hyperbaric solutions) in random order and in a double-blind fashion. A 24-gauge Sprotte spinal needle was placed at the L2-3 interspace. The level of analgesia to pinprick was determined moving cephalad in the midclavicular line until a dermatome was reached at which the prick felt as sharp as over an unblocked dermatome. One dermatome caudad to this point was recorded every 5 minutes as the level of analgesia. We also recorded the times to voiding, unassisted ambulation, and complete resolution of sacral anesthesia. RESULTS: There was no difference between tetracaine and bupivacaine in time taken for two- and four-segment regression of the analgesia level. However, times to ambulation and complete resolution of the block were significantly shorter with bupivacaine then with tetracaine. With lidocaine, times to four-segment regression, ambulation, voiding, and complete regression of the block were significantly shorter than with bupivacaine and tetracaine. Time to two-segment regression did not differ among local anesthetics. Back and radicular pain symptoms were reported by three subjects after lidocaine subarachnoid block but not after tetracaine or bupivacaine. CONCLUSION: Among individual subjects, lidocaine exhibited the shortest recovery profile. However, the recovery profiles of the three anesthetics were very variable between subjects. Time to meeting discharge criteria after bupivacaine or tetracaine was faster in a few subjects than that after lidocaine in other subjects. For ambulatory anesthesia, times to two- and four-segment regression do not accurately predict time to readiness for discharge after spinal anesthesia.