Tracheal deviation with phrenic nerve palsy after brachial plexus block.

We present a case of a woman who received a left single-injection supraclavicular brachial plexus block for analgesia to facilitate upper extremity orthopaedic surgery. Before tracheal extubation she desaturated, was noted to have a low tidal volume and reduced left-sided air entry on auscultation of the chest. A chest x-ray taken 1 h following tracheal extubation revealed elevation of the left hemidiaphragm and a rightward shift of the trachea and mediastinal structures, with no evidence of pneumothorax. Findings were in-keeping with phrenic nerve palsy complicating the brachial plexus block performed. The patient was asymptomatic and discharged home the next day following repeat chest x-rays. We believe this is the first report of tracheal deviation contralateral to the side of an elevated hemidiaphragm secondary to phrenic nerve palsy from a brachial plexus block.

The crossed-leg position increases the dimensions within the acoustic target window for neuraxial needle placement in term pregnancy: a prospective observational study.

INTRODUCTION: Neuraxial anesthesia in obstetric patients may be difficult to achieve due to anatomical changes in pregnancy. The crossed-leg position may help in optimizing patient position. We prospectively evaluated the utility of the crossed-leg position compared with a standard position using ultrasound measurements. METHODS: Thirty women with term singleton pregnancy admitted for vaginal delivery were recruited. Women with a history of spinal trauma or surgery, congenital spinal abnormality, advanced first stage of labor or a language barrier were excluded. Two anesthesiologists, blinded to each other's measurements, scanned each subject in the crossed-leg position and standard position. Measurements of the lengths of the posterior longitudinal ligament, ligamentum flavum and interlaminar distance were recorded at the L3-L4 interspace. Comfort level in each position was scored on a Likert Scale. RESULTS: Twenty-nine women completed the study (complete data n=28). Significant increases were observed in the lengths of the posterior longitudinal ligament (mean difference 2.2 mm, 95% CI 1.3 to 3.2; P <0.001), ligamentum flavum (mean difference 1.4 mm, 95% CI 0.7 to 2.1; P <0.001) and interlaminar distance (mean difference 1.4 mm, 95% CI 0.4 to 2.5; P=0.006) in the crossed-leg position. No significant differences in comfort were observed. CONCLUSION: We demonstrated a significant increase in the sonographically measured lengths of the posterior longitudinal ligament, ligamentum flavum and interlaminar distance in the crossed-leg position when compared with the standard position. Both positions were comfortable. Further studies should explore whether these findings translate clinically into easier needle placement in the crossed-leg position.

Efficacy of the Epidural Positioning Device® in optimizing the acoustic target window for neuraxial needle placement in term pregnancy.

BACKGROUND: Neuraxial anesthesia can be challenging in obstetric patients due to the gravid uterus interfering with patient positioning. Ultrasound is commonly used in obstetric anesthesia to facilitate neuraxial needle placement. Some positioning maneuvers facilitate the ultrasound visualization of structures and the placement of neuraxial needles, but the Epidural Positioning Device (EPD) has yet to be evaluated. OBJECTIVES: Our goal was to evaluate whether the use of the EPD increased the acoustic target window in the lumbar area of pregnant patients. We hypothesized that the application of the EPD would increase the measured lengths of the paravertebral longitudinal ligament (PLL), the interlaminar distance (ILD) and the ligamentum flavum (LF). METHODS: Lumbar ultrasonography was performed on 29 pregnant women having an elective cesarean delivery. Two anesthesiologists independently scanned the L3-4 right paramedian space, using a curvilinear ultrasound transducer, in two positions for each patient: traditional sitting with lumbar flexion and sitting with use of the EPD for lumbar flexion. The PLL, ILD and LF lengths were measured using the ultrasound caliper software and recorded, with the anesthesiologists blinded to the results. Patients were asked to rate their comfort in both positions. RESULTS: There were no significant differences between the measured lengths of the PLL, ILD and LF in the two positions. Patient comfort was significantly higher with use of the EPD (OR 10, 95% CI 2.4 to 88). CONCLUSION: Although the application of an EPD did not improve the paramedian acoustic target area in term parturients, greater patient comfort might facilitate needle placement.

Onset of labour epidural analgesia with low-dose bupivacaine and different doses of fentanyl.

This study investigated the effects of different doses of epidural fentanyl on the time to onset of epidural analgesia in women in early labour. We hypothesised that onset of epidural labour analgesia (the primary outcome defined as time in minutes from completion of epidural bolus to the first uterine contraction with a numeric pain rating scale [NPRS] score ≤ 3) would be faster with 100 µg of fentanyl epidural bolus compared with 20 µg or 50 µg. Epidural labour analgesia was initiated with 20 µg of fentanyl (F20 group), 50 µg (F50 group) or 100 µg (F100 group) along with 10 ml bupivacaine 0.08% as the loading dose. We randomly allocated 105 patients, with 35 patients in each group. Median (IQR [range]) time to achieve NPRS ≤ 3 was 18 (11-30 [6-20]) min in F20, 10 (8-19 [4-30]) min in F50 and 10 (6-16 [3-30]) min in F100 groups. There was a significant difference in onset times comparing F100 with F20 (p < 0.001) and F50 with F20 (p = 0.007), but not significantly different comparing F100 with F50 (p = 0.19). The median (IQR [range]) time from the epidural loading dose to first patient controlled epidural analgesia bolus was 61 min (20-165 [20-420]) in F20, 118 min (66-176 [20-396]) in F50 and 150 min (66-214 [30-764]) in F100 groups. This was not statistically significant (p = 0.16) comparing the F20 with the F100 group. There were no significant differences in maternal side-effects, mode of delivery, patient satisfaction scores or neonatal Apgar scores between all groups. We conclude that the 50 µg and 100 µg fentanyl doses were associated with reduced onset times to effective analgesia compared with the 20 µg dose.

Prevention of post-dural puncture headache in parturients: a systematic review and meta-analysis.

Post-dural puncture headaches (PDPHs) present an important clinical problem. We assessed methods to decrease accidental dural punctures (ADPs) and interventions to reduce PDPH following ADP. Multiple electronic databases were searched for randomised clinical trials (RCTs) of parturients having labour epidurals, in which the studied intervention could plausibly affect ADP or PDPH, and the incidence of at least one of these was recorded. Forty RCTs (n = 11,536 epidural insertions) were included, studying combined spinal-epidurals (CSEs), loss of resistance medium, prophylactic epidural blood patches, needle bevel orientation, ultrasound-guided insertion, epidural morphine, Special Sprotte needles, acoustic-guided insertion, administration of cosyntropin, and continuous spinal analgesia. The RCTs for CSE, loss of resistance medium, and prophylactic epidural blood patches were meta-analysed. Five methods reduced PDPH: prophylactic epidural blood patch {four trials, median quality score = 2, risk difference = -0.48 [95% confidence interval (CI): -0.88 to -0.086]}, lateral positioning of the epidural needle bevel upon insertion (one trial, quality score = 1), Special Sprotte needles [one trial, quality score = 5, risk difference = -0.44 (95% CI: -0.67 to -0.21)], epidural morphine [one trial, quality score = 4, risk difference = -0.36 (95% CI -0.59 to -0.13)], and cosyntropin [one trial, quality score = 5, risk difference = -0.36 (95% CI -0.55 to -0.16)]. Several methods potentially reduce PDPH. Special Sprotte needles, epidural morphine, and cosyntropin are thus far each supported by a single, albeit good quality trial. Prophylactic blood patches are supported by three trials, but these had flawed methodology. Mostly, trials were of limited quality, and further well-conducted, large studies are needed.

Anaesthetic management of a pregnant woman with carcinoid disease.

Carcinoid tumours are neuroendocrine in origin and release vasoactive substances. Carcinoid tumours may be associated with carcinoid syndrome in 2-5% of patients and result in haemodynamic instability, bronchospasm, volume and electrolyte imbalance, and hyperglycaemia. We present the anaesthetic management of a 29-year-old parturient with metastatic carcinoid tumour. Although our patient did not ultimately develop carcinoid syndrome during the peripartum period, it was important that we used a multidisciplinary team approach, with close monitoring of her antenatal progress, and planned epidural analgesia for labour and delivery.

A study on large radial motion of arteries in vivo.

This study analyses the radial periodic motion of an artery which is modelled as a thin cylinder of uniform cross-section subjected to dynamic inner pressure using the theory of finite deformation of elastic materials. The arterial tissue properties (anisotropy, homogeneity and incompressibility) are taken into account in an analysis based on the use of the strain energy function. The validity of the mathematical analysis is illustrated through numerical computation applying the available in vivo data for elastic constants of the canine middle descending thoracic aorta to the expressions for the intramural pressure and circumferential stresses obtained by solving the necessary equation of motion together with the boundary conditions. Results obtained in this study indicate very low stresses which suggest that the arteriosclerosis resulting from high stress gradients is effectively ruled out in this model.

Effect of tonicity on glucose absorption and histomorphology of rat intestinal mucosa.

Perfusion of the gut lumen with 2 ml of isotonic solutions showed uniform absorption of glucose and water over the four 15-minutes study periods, the absorption being maximum in jejunum and least in colon. With hypertonic solutions the glucose absorption decrease was related to the increasing osmolarity and duration of exposure to the solution as well as the nature of the substance used. Histological changes reflecting impaired functions were localised to the tips of the villi and were observed on exposure to hypertonic solution for 45 minutes or more.