Neurological and humoral control of blood pressure

There is a relationship between arterial blood pressure, cardiac output and vascular resistance which can be described mathematically, and helps us to understand the short-term control of blood pressure in the terms of a hydraulic system. The sensors in this system are the arterial baroreceptors which mediate changes in the hydraulic system though control of the autonomic nervous system, which in turn influences heart rate, inotropy and vascular tone. Altering the distribution of blood between the arterial and venous systems compensates for acute changes in total blood volume. The total blood volume is controlled predominantly by the kidney, with the renin–angiotensin–aldosterone system acting as both the ‘sensor’ of blood pressure/volume (via renin release in the juxtaglomerular apparatus) and the ‘effector’ of blood pressure/volume (via aldosterone secretion by the adrenal cortex). Overall control is shared; the baroreceptors being responsible for mediating short-term changes, and renal mechanisms determining the long-term control of blood pressure. These systems have to be adaptable in order to deal with physiological variation in the delivery of blood to tissues from rest to exercise, and with the large shifts in blood volume seen in acute haemorrhage. Pathophysiological changes in these systems lead to maladaptive responses, with systemic hypertension the most commonly seen.     

Oclusión temporal con balón de las arterias hipogástricas en una paciente con acretismo placentario

Placenta accreta spectrum is an abnormal placentation that results in an increase in maternal morbidity and mortality, which mostly occurs due to severe haemorrhage. We present the case of a patient diagnosed prenatally with placenta accreta spectrum, premature rupture of membranes and bleeding, who was managed by a multidisciplinary team. Temporary bilateral hypogastric balloon occlusion was placed before caesarean hysterectomy, with good results for the mother.     

Cell layers and neuropil: contrast‐enhanced MRI of mouse brain in vivo

Contrast‐enhanced T₁‐ and T₂‐weighted MRI at 9.4 T and in‐plane resolutions of 25 and 30 µm has been demonstrated to differentiate between neural tissues in mouse brain in vivo, including granule cell layers, principal cell layers, general neuropil, specialized neuropil and white matter. In T₁‐weighted MRI of the olfactory bulb, hippocampus and cerebellum, contrast obtained by the intracranial administration of gadopentetate dimeglumine (Gd‐DTPA) reflects the extra‐ and intracellular spaces of gray matter in agreement with histological data. General neuropil areas are highlighted, whereas other tissues present with lower signal intensities. The induced contrast is similar to that in plain T₂‐weighted MRI, but offers a 16–30‐fold higher contrast‐to‐noise ratio. Systemic administration of manganese chloride increases the signal‐to‐noise ratio in T₁‐weighted MRI to a significantly greater extent in principal cell layers and specialized neuropil than in granule cell layers, whereas gadolinium‐enhanced MRI indicates no larger intracellular spaces in these tissues. Granule cell layers are enhanced no more than general neuropil by manganese, whereas gadolinium‐enhanced MRI indicates significantly larger intracellular spaces in the cell layers. These discrepancies suggest that the signal increase after manganese administration reflects cellular activity which is disproportionate to the intracellular space. As a result, principal cell layers and specialized neuropil become highlighted, whereas granule cell layers, general neuropil and white matter present with lower signal intensities. Copyright © 2013 John Wiley & Sons, Ltd.     

Multifocal haemorrhagic brain damage following hypoxia and blood pressure lability: case report and rat model

P. S. Pahlavan, W. Sutton, R. J. Buist and M. R. Del Bigio (2012) Neuropathology and Applied Neurobiology 38 , 723–733 Multifocal haemorrhagic brain damage following hypoxia and blood pressure lability: case report and rat model Aims: Haemorrhagic brain damage is frequently encountered as a complication of premature birth. Much less frequently, multifocal petechial haemorrhage is identified in asphyxiated term newborns. Our goal was to develop an experimental rat model to reproduce this pattern of brain damage. Methods: Neonatal rat pups were exposed to a 24‐h period of 10% or 8% hypoxia followed by a single dose of phenylephrine. Acute and subacute changes, as well as long‐term outcomes, were investigated by histology, brain magnetic resonance imaging and behavioural assessment. Immunostaining for vascular endothelial growth factor and caveolin‐1 was performed in the rat brains as well as in a 17‐day human case. Results: Small foci of haemorrhage were identified in almost all regions of the rat brain subjected to hypoxia plus phenylephrine, but not hypoxia alone. Exposure to 8% hypoxia was associated with more haemorrhagic foci than 10% hypoxia. With rare exceptions, the blood deposits were too small to be detected by magnetic resonance imaging. Altered immunohistochemical detection of vascular endothelial growth factor and caveolin‐1 in the child and the rat model suggests a role for blood–brain barrier compromise. There were no clear behavioural changes and no residual morphological abnormalities in the 78‐day follow‐up of the rats. Conclusions: We conclude that transient hypoxia, in a dose‐dependent manner, can weaken the vasculature and predispose to brain haemorrhage in the situation of labile blood pressure. Persistent hypoxia is likely to be important in the genesis of permanent severe brain damage.     

Avoidable maternal deaths: Three ways to help now

Abstract

The current paper examines the realities of women delivering in resource-poor settings, and recommends cost-effective, scalable strategies for making these deliveries safer. Ninety-five percent of maternal deaths occur in poor settings, and the largest proportion of these deaths are women who deliver at home, far away from health care facilities, and without financial access to skilled providers. This situation will improve only when policymakers and programme planners refocus their attention on service delivery and financing interventions, with the potential to reach the largest portion of women living in places where mortality is the highest. We suggest three feasible interventions that can potentially minimise both demand and supply side problems of safe delivery: (1) misoprostol to treat postpartum haemorrhage, an easy to use and heat stable technology to reduce the leading cause of maternal deaths; (2) alternative providers, such as clinical officers, trained to offer emergency obstetric care services; (3) financing safe delivery through vouchers or other mechanisms that can be implemented in poor settings and made attractive to the donor community through output-based assistance (OBA).     

A case study of community-based distribution and use of Misoprostol and Chlorhexidine in Sokoto State,Nigeria

The United States Agency for International Development/Targeted States High Impact Project supported Sokoto State, Nigeria government in the development of a community-based intervention aimed at preventing post-partum haemorrhage (PPH) and cord infection among women and children, respectively. This paper describes the innovative intervention within the Nigeria health delivery system. It then explains the case study approach to assessing this intervention and summarises findings. Ultimately, the intervention was received well in communities and both drugs were added to the procurement list of all health facilities providing maternity services in the State. Key factors leading to such success include early advocacy efforts at the state-level, broad stakeholder engagement in designing the distribution system, early community engagement about the value of the drugs and concerted efforts to monitor and ensure availability of the drugs. Implementation challenges occurred in some areas, including shortage of community-based health volunteers (CBHVs) and drug keepers, and socio-cultural barriers. To maximise and sustain the effectiveness of such interventions, state government needs to ensure constant drug supply and adequate human resources at the community level, enhance counselling and mobilisation efforts, establish effective quality improvement strategies and implement a strong M&E system.     

Risk factors for bleeding after dental extractions in patients over 60 years of age who are taking antiplatelet drugs

The aim of this retrospective, single-centre study was to identify the risk factors for bleeding after dental extractions in patients aged over 60 who were being treated with antiplatelet drugs. A total of 338 patients who fulfilled the inclusion criteria were enrolled, and their personal and clinical details, and complications with bleeding after extraction, were retrieved and recorded. There were 182 men and 156 women (mean (SD) age 72 (8) years). A total of 469 teeth were extracted, with a mean (SD) of 1.4 (0.6) teeth/patient. Seventy-seven patients (23%) developed mild, and 55 (16%) severe, bleeding postoperatively. No patient developed a major cardiovascular or cerebrovascular event. We calculated the significance of the association of different variables with the occurrence of postoperative haemorrhage using a multivariate stepwise logistic regression model. The presence of three or more coexisting conditions, a complicated tooth extraction, and the use of two antiplatelet drugs were independent risk factors, while discontinuation of antiplatelet treatment four or more days before the tooth was extracted was a protective factor. This suggests that clinicians should assess the thrombotic risk associated with the interruption of antiplatelet drugs as well as the risk of bleeding for each patient before dental extraction. Strong and effective measures for haemostasis may be preferred over blind discontinuation of antiplatelet drugs. This study is registered in the Chinese Clinical Trial Registry (No. ChiCTR1800014355).     

Hématome rétroplacentaire. Diagnostic,prise en charge et pronostic maternofœtal : étude rétrospective de 100 cas

ObjectivesTo update knowledge on placental abruption because there are few recent series published although the perinatal care has progressed.Patients and methodsA retrospective observational study has been conducted on 100 consecutive cases of abruptio placentae, occurring from January 2008 to June 2011, in the two maternity units of the University Hospital of Strasbourg (France).ResultsOne hundred and five births among which five twin pregnancies were included. Clinical context was evident in 91% of cases, but the classic clinical triad was present in only 4% of cases. Clots were found at immediate placenta examination in 77% of cases. Pathological diagnosis was directly in accordance with clinical diagnosis in half the cases. Mean date of childbirth was 33 weeks of amenorrhea and 6 days. Sixty-seven patients gave birth prematurely. Among them, 50 patients delivered before 34 weeks. Sixty caesareans were performed in emergency before labor, including 47 with general anesthesia. Twelve patients had post-partum haemorrhage and ten coagulation disorders. There was no maternal death. Perinatal mortality was 19% with 13 fetal deaths in utero (12.4%), four children born in an apparent death state with resuscitation failure (3.8%) and three neonatal deaths (2.8%).Discussion and conclusionPlacental abruption is a serious and unpredictable situation. Joint medical care of obstetricians and intensivists is often required. Perinatal mortality mainly occurs in utero.