Crystallization of ropivacaine and bupivacaine when mixed with different adjuvants: a semiquantitative light microscopy analysis.

INTRODUCTION: Amino-amide local anesthetics precipitate when mixed with some commonly used adjuvants, carrying the risk of perineural or vascular crystal deposition. The aim of this study was to evaluate whether crystallization occurs with routinely used local anesthetic-adjuvant combinations and if a relation with the solution's pH exists. METHODS: All substances used in this trial were first visually investigated undiluted under tenfold magnification. Grade of crystallization was assessed using a 6 point grading system.Ropivacaine (0.2%, 0.75% and 1%) and bupivacaine (0.25% and 0.5%) were mixed in a 1:1 solution with the following adjuvants: dexamethasone, dexmedetomidine, clonidine, fentanyl, sodium bicarbonate 8.4% and sodium chloride 0.9%. Subsequently, ropivacaine (0.2% and 0.75%) and bupivacaine (0.25% and 0.5%) were mixed with adjuvants in concentrations commonly used in clinical practice and then serially assessed at several time points up to 1 hour. pH of all substances/combinations was assessed and correlated with crystallization grade. RESULTS: All pure substances-except the reference standards sterile water and triamcinolon-showed crystallization grades ranging from grade 1 to grade 4. Addition of adjuvants lead to variable, unpredictable changes in crystal depositions. Addition of sodium bicarbonate 8.4% produced heavy crystallization in all combinations. Grade of crystallization was weakly positively related to the pH of the solution in 1:1 mixtures and clinically relevant concentrations, but not in pure substances. DISCUSSION: Our study showed that crystallization is present in pure local anesthetics and may be increased or decreased by admixture of adjuvants. Higher pH of mixtures was weakly associated with more crystallization. Further research is necessary to translate these findings into clinical practice.

The impact of dexamethasone as a perineural additive to ropivacaine for PECS II blockade in patients undergoing unilateral radical mastectomy - A prospective, randomized, controlled and double-blinded trial.

STUDY OBJECTIVE: Dexamethasone is commonly used as an adjuvant to local anesthetics to prolong duration of peripheral nerve blocks with minimal side-effects. The present study investigates the efficacy of dexamethasone added to ropivacaine 0.2% as compared to ropivacaine 0.2% alone for pectoral nerves block II (PECS II) in unilateral radical mastectomy. DESIGN: A prospective, randomized, controlled and double-blinded trial. SETTING: The study was performed at Innsbruck Medical University Hospital, Austria, between January 2019 and October 2020. PATIENTS: Sixty female patients with an American Society of Anesthesiologists Score I-II (18-90 years, BMI 18-35) scheduled for unilateral radical mastectomy without one-stage immediate autologous breast reconstruction were randomly assigned to receive PECS II block with ropivacaine 0.2% with or without dexamethasone 8 mg. INTERVENTIONS: Patients were randomly assigned to receive PECS II block with ropivacaine 0.2% with or without dexamethasone 8 mg. MEASUREMENTS: Primary outcome parameter was the cumulative opioid consumption during the first 72 postoperative hours. Secondary outcome parameters were the duration of analgesia and the course of the visual analogue scale (VAS) and the area under the curve VAS (AUC-VAS). MAIN RESULTS: There was no difference in cumulative opioid consumption after 72 h between the ropivacaine 0.2% plus dexamethasone group and the ropivacaine 0.2% plus placebo group (11.89 vs 11.90 morphine milligram equivalent, respectively; p 0.831). Duration of analgesia also did not differ significantly between the ropivacaine 0.2% plus dexamethasone group and the ropivacaine 0.2% plus placebo group (12.75 versus 8.75 h, respectively; p 0.680). There also was no difference in the course of VAS and AUC-VAS. CONCLUSIONS: Dexamethasone 8 mg when added to ropivacaine 0.2% for PECS II block in unilateral radical mastectomy was not found to reduce total opioid consumption over 72 postoperative hours or to prolong duration of analgesia as compared to pure ropivacaine 0.2%.

Cerebrospinal beta-amyloid peptides(1-40) and (1-42) in severe preeclampsia and HELLP syndrome - a pilot study.

During pregnancy, substantial alterations in cerebral plasticity, vascular remodeling and neuronal growth occur in the maternal brain. We investigated whether concentrations of selected neurodiagnostic biomarkers in the cerebrospinal fluid of women with preeclampsia/HELLP syndrome differ from those in healthy controls using enzyme-linked immunosorbent assay technique. We found that tau protein concentrations (p = 0.016) and phospho-tau/tau ratio (p < 0.001) in cerebrospinal fluid were significantly lower in 39 preeclamptic women compared to 44 healthy controls during third trimester of pregnancy. Beta-amyloid(1-40)/(1-42) ratio was significantly higher in HELLP syndrome than in severe preeclampsia (8.49 + 2.73 vs. 4.71 + 1.65; p = 0.007). We conclude that beta-amyloid(1-40)/(1-42) ratio in cerebrospinal fluid can discriminate severe preeclampsia and HELLP syndrome. High beta-amyloid peptide and low tau protein concentrations are associated with impaired development of the materno-feto-placental unit and correlate with placental dysfunction.

Experience on the way to totally endoscopic atrial septal defect repair.

BACKGROUND: Remote-access perfusion and robotics have enabled totally endoscopic closure of atrial septal defect (ASD) and patent foramen ovale (PFO). We report on a stepwise approach to a totally endoscopic procedure. METHODS: Seventeen patients (median age, 39 years; range, 21-55 years) underwent limited-access ASD or PFO closure. As a preparative step, the operation was carried out through minithoracotomy in 11 patients. In parallel, experience with robotic surgery was gained with totally endoscopic coronary artery bypass grafting procedures. After performance of ASD closures in dry-laboratory models using the da Vinci telemanipulation system, 6 patients were operated on in a totally endoscopic fashion. RESULTS: With the endoscopic approach, significant learning curves were noted for cardiopulmonary bypass time y(min) = 226 - 41 * ln(x) (P = .03) and aortic cross-clamp time y(min) = 134 - 42 * ln(x) (P = .01) (x = number of procedures). There was no hospital mortality, and no residual shunts were detected at postoperative echocardiography. Median ventilation time was 9 hours (range, 0-18 hours) for the minithoracotomy group and 6 hours (range, 4-19 hours) for the totally endoscopic group. Median intensive care unit stay was 20 hours (range, 18-24 hours) and 18 hours (range, 18- 120 hours), respectively. CONCLUSIONS: The implementation of robotic totally endoscopic closure of ASD or PFO in a heart surgery program seems to be safe. An intermediate step of performing the operations through minithoracotomy, adapting to remote access perfusion systems, and gaining experience in other robotic cardiac surgical procedures seems worthwhile. Learning curves are apparent, and adequate defect closure does not seem to be compromised by the totally endoscopic approach.

Cervical and high thoracic ligamentum flavum frequently fails to fuse in the midline.

BACKGROUND: Cervical and high thoracic epidural anesthesia and analgesia have gained increasing importance in the treatment of painful conditions and as components of anesthetics for cardiac and breast surgery. In contrast to the hanging-drop technique, the loss-of-resistance technique is thought to rely on the penetration of the ligamentum flavum. However, the exact morphology of the ligamentum flavum at different vertebral levels remains controversial. Therefore, the aim of this study was to investigate the incidence and morphology of cervical and high thoracic ligamentum flavum mid-line gaps in embalmed cadavers. METHODS: Vertebral column specimens were obtained from 52 human cadavers. On each dissected level, ligamentum flavum mid-line gaps were recorded and evaluated with respect to shape and size. RESULTS: The following variations were encountered: complete fusion in the mid-line, mid-line fusion with a gap in the caudal part, mid-line gap, and mid-line gap with widened caudal end. The incidence of mid-line gaps at the following levels was: C3-C4: 66%, C4-C5: 58%, C5-C6: 74%, C6-C7: 64%, C7-T1: 51%, Th1-Th2: 21%, Th2-Th3: 11%, Th3-Th4: 4%, Th4-Th5: 2%, and Th5-Th6: 2%. The mean width of mid-line gaps was 1.0 +/- 0.3 mm. CONCLUSIONS: In conclusion, the present study shows that gaps in the ligamenta flava are frequent at cervical and high thoracic levels but become rare at the T3/T4 level and below, such that one cannot always rely on the ligamentum flavum as a perceptible barrier to epidural needle placement at these levels.