Respiratory arrest in patients undergoing arteriovenous graft placement with supraclavicular brachial plexus block: a case series

Supraclavicular brachial plexus block is commonly used for upper extremity surgery. Respiratory arrest in three patients with end-stage renal disease after ultrasound-guided supraclavicular brachial plexus block for creation of an arteriovenous graft over a 6-month period is presented. Patients with renal failure may represent a group at particular risk for respiratory failure following supraclavicular brachial plexus block.     

Model studies of the effects of the thoracic pressure on the circulation

Two models of the cardiovascular system subjected to changes in intrathoracic pressure (ITP) are used to simulate the response to normal and positive pressure ventilation and the Mueller maneuver. The first model, based on our earlier model for cardiopulmonary resuscitation and cardiac assist by ITP variations, is based on lumped parameter representation of the cardiovascular system with two ventricles which function based on the time-varying elastance concept using their transmural pressures as the load. The ITP is assumed to be equally distributed in the thoracic cavity and equally affecting all cardiovascular structures within the chest. The model shows that a decrease in ITP is associated with an initial decrease in aortic pressure and flow and an increase in left ventricular end-diastolic and end-systolic volumes. A transient decrease in left ventricular volume which was suggested to occur by a few studies cannot be predicted based on this model. Such a decrease in left ventricular volume can be only predicted when a pericardial constraint is included, as done in the second model. Positive pressure interventions are associated with decreased heart volumes and cardiac output which is primarily a “preload” effect. In general the model reasonably predicts the hemodynamics as a function of the ITP changes and may be used as a tool to investigate the response of the cardiovascular system to various ITP interventions.     

The mid-gestation triple test profile among women diagnosed with vasa previa

Purpose: To assess the mid-trimester triple test biomarkers among women diagnosed with vasa previa (VP).

Methods: The study included 43 singleton pregnancies diagnosed with vasa previa between the years 1988 and 2011. The mid-gestation screening test for Down syndrome was calculated from the combination of triple serum markers and maternal age, and expressed as a multiple of the gestation specific normal mean (MoM). Reference MoM values were calculated from the local population. The levels of mid-gestation maternal serum alpha-fetoprotein (AFP), human chorionic gonadotropin (hCG), and unconjugated estriol (uE3) of patients with VP were compared with control reference group.

Results: The mean hCG and αFP levels of women diagnosed with VP was significantly higher compared to control reference group (1.42 versus 0.99 MoM; p?p?3 levels between these two groups (0.99 versus 0.98 MoM; p?=?.71).

Conclusions: Our findings suggest that increased mid-gestation hCG and AFP were found among pregnancies complicated with VP. Clinicians should consider targeted scanning of pregnant women with risk factors for VP, including unexplained high maternal levels of hCG and αFP of the triple test, while conducting mid-gestation anomaly scan.     

APOE genotype influences functional status among elderly without dementia

The presence of apolipoprotein-?4 (APOE-?4) significantly increases the risk of Alzheimer's disease (AD). The association between APOE-?4 status and functional abilities was explored further in a multicultural sample of community-dwelling, non-demented elders. The sample was limited to cognitively-intact, community-dwelling elders, who were free of stroke or other neurologic disability. In 218 elders who met research criteria, the presence of APO-?4 was associated with poorer functional status, apart from the effects of neuropsychological performance, gender, age, and education (OR = 2.5, 95% CI: 1.3, 4.9). In 158 subjects without an APOE-?4 allele, 50% reported no functional limitation; in the 60 subjects with an ?4 allele, only 28% reported no functional limitation (P < .01). The relationship was not explained by the distribution of co-morbidities. The association between poorer function and the presence of an APOE-?4 allele was evident in each ethnic group. In path analyses, the presence of an APOE-?4 allele was associated with decreased functional ability in non-demented elders not simply through an association with poorer cognitive status, but also independently. These results suggest that the APOE-?4 genotype is associated with functional deficit in people with normal neuropsychological profiles. © 1995 Wiley-Liss, Inc.     

Phonological dyslexia without phonological impairment?

RG, a patient with probable Alzheimer's disease, showed a severe impairment in nonword reading. RG's word reading was intact, for example, as demonstrated by her scores in standardised reading tasks, which were comparable to those of normal controls. No phonological impairment was apparent in speech production and comprehension. Moreover, RG performed well in a series of phonological tasks (e.g., production of a rhyming word, phoneme identification) on which patients with a reading deficit selective for nonwords have been reported to encounter problems. RG's data severely constrain reading models proposing that nonword reading deficits are caused by phonological deficits. However, RG's data are compatible with dual-route reading models, which do not propose a link between nonword reading deficits and phonological impairment.     

Age-related changes in brain activation during a delayed item recognition task

To test competing models of age-related changes in brain functioning (capacity limitation, neural efficiency, compensatory reorganization, and dedifferentiation), young (n=40; mean age=25.1 years) and elderly (n=18; mean age=74.4 years) subjects performed a delayed item recognition task for visually presented letters with three set sizes (1, 3, or 6 letters) while being scanned with BOLD fMRI. Spatial patterns of brain activity corresponding to either the slope or y-intercept of fMRI signal with respect to set size during memory set encoding, retention delay, or probe stimulus presentation trial phases were compared between elder and young populations. Age effects on fMRI slope during encoding and on fMRI y-intercept during retention delay were consistent with neural inefficiency; age effects on fMRI slope during retention delay were consistent with dedifferentiation. None of the other fMRI signal components showed any detectable age effects. These results suggest that, even within the same task, the nature of brain activation changes with aging can vary based on cognitive process engaged.     

A novel compound heterozygous mutation of the luteinizing hormone receptor –implications for fertility

The luteinizing hormone/chorionic gonadotropin receptor (LHCGR) belongs to the family of G-protein coupled receptors and binds both luteinizing hormone (LH) and human chorionic gonadotropin (hCG). Ligand-receptor interaction mediates a downstream cascade of events which is essential for ovulation in women, and expression of the male phenotype in men. The human LHCGR gene consists of 11exons and 10 introns. Homozygous and compound heterozygous mutations may inactivate the receptor by altering its structure and subsequent function. Herein we reported a novel, compound heterozgygous inactivating LHCGR mutation in a woman who presented with secondary infertility, having previously carried to term a donor oocyte pregnancy. A 27 bp deletion was detected in exon I at amino acid number 12. This mutation involved the signal peptide region, which is important for protein targeting, maturation and cellular expression. Another mutation involving a 2 base pair (thymine and cytosine) deletion was detected in exon 11 at amino acid number 586. This deletion produced a frameshift resulting in a premature stop codon and a truncated protein. An XY sibling with the same mutations was phenotypically female and misdiagnosed as complete androgen insensitivity syndrome. Other unaffected family members were genetically tested and carried one of the two mutations.     

Improved epidural analgesia in the parturient in the 30° tilt position

PURPOSE: To compare the incidence of incomplete analgesia when epidural local anesthetic is administered with the parturient supine in a 30 degree leftward tilt or in the left lateral decubitus position. METHODS: After placement of a multiorifice catheter 5 cm into the epidural space, 293 women in active labour were randomly positioned either to the left lateral decubitus position (lateral group) or supine with a 30 degree leftward tilt (tilt group) and then received 13 mL bupivacaine 0.25%. The success of the epidural block was determined by asking the patient if she required additional medication 15 min later. The incidence of complications (fetal heart rate decelerations, hypotension, and ephedrine usage) was noted. RESULTS: In the lateral group, 38% required additional medication compared with 24% in the tilt group (P = 0.006). There were no differences between groups in the incidence of maternal hypotension or fetal heart rate decelerations, but more women (10%) received ephedrine in the lateral than in the tilt group (4%), P = 0.035. CONCLUSIONS: Placing the parturient supine with a 30 degree leftward tilt is associated with a greater success rate of labour epidural analgesia without an increase in complications than in women in the left lateral decubitus position. This advantage should be considered when positioning the parturient after epidural catheter placement.