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Third Stage Of Labor
Published in Vincenzo Berghella, Obstetric Evidence Based Guidelines, 2022
Alyssa R. Hersh, Jorge E. Tolosa
Ergot alkaloids cause sustained tonic contraction of uterine smooth muscle by stimulation of alpha-adrenergic myometrial receptors. The dose is 0.2 mg IM injection or PO (orally), with a mean elimination half-life of 3.4 hours (range 1.5–12.7 hours). IV administration is not recommended, as it is associated with more severe side effects. Nausea and vomiting are common side effects, although the most concerning side effect is vasoconstriction of the vascular smooth muscle. This results in elevation of central venous pressure and systemic blood pressure, increasing the risk of pulmonary edema, stroke, or myocardial infarction. Contraindications include cardiac disease, autoimmune diseases associated with Raynaud phenomena, peripheral vascular disease, arteriovenous shunts, hypertension, preeclampsia, and eclampsia.
Embryology, Anatomy, and Physiology of the Adrenal Glands
Published in Karl H. Pang, Nadir I. Osman, James W.F. Catto, Christopher R. Chapple, Basic Urological Sciences, 2021
Zona fasciculata (ZF)Constitutes up to 75% of the cortex.Secretes mainly cortisol glucocorticoid and some androgen precursors.Cortisol increases in response to stress. Maintains blood pressure (increases the effect of vasoconstrictors).Suppresses the immune system.Increases gluconeogenesis and decreases peripheral glucose uptake.Activates lipolysis.Bone resorption.Skin thinning.
Neural Control of the Intestinal Circulation and its Interaction With Autoregulation
Published in Irving H. Zucker, Joseph P. Gilmore, Reflex Control of the Circulation, 2020
Gerald A. Meininger, Harris J. Granger
In previous studies we investigated the ability of intestinal autoregulation to interact with the a-agonist phenylephrine and the nonneural vasoconstrictor angiotensin II. In these studies rats were instrumented with a Doppler flow probe and vascular occluder on the superior mesenteric artery. A downstream jejunal artery was cannulated for measurement of intestinal perfusion pressure and the brachial artery and vein were cannulated for measurement of systemic arterial pressure and infusion of the vasoconstrictors, respectively. Pressure-flow relationships for the intestinal circulation were determined by inflating the vascular occluder to reduce intestinal perfusion pressure in controlled steps. This was done before and during infusion of various doses of vasoconstrictor. An index of autoregulatory capacity was calculated from the pressure-flow data by dividing the fractional change in flow by the fractional change in pressure. This index is referred to as fractional compensation. Using this index a fractional compensation of 1.0 indicates perfect autoregulation and a fractional compensation of 0 indicates no autoregulation (i.e., analogous to a rigid tube). Fractional compensations less than 1.0 but greater than 0 denote the quantitative ability of autoregulation to return flow partially toward normal.
Cardiovascular responses to hot skin at rest and during exercise
Published in Temperature, 2023
Ting-Heng Chou, Edward F. Coyle
One may notice that there is an inconsistency regarding the control of cutaneous vasoconstrictor and vasodilator pathways by exercise. The onset of exercise only increases vasoconstrictor activity, whereas the delayed initiation of active cutaneous vasodilation and the lower upper limit of skin blood flow are only controlled by inhibition of the vasodilation system. The explanation is that the classical “exercise reflexes” affect the vasoconstrictor system as in other vascular beds at the onset of exercise [5], whereas changes in plasma osmolality affect the vasodilator system and delay the initiation of cutaneous vasodilation. The lower upper limit of skin blood flow during exercise is achieved by limiting the active vasodilator system, but the specific mechanism is unknown. In addition, the effect of vasoconstrictor activity on cutaneous blood flow may be too small once the active cutaneous vasodilation is triggered to lower skin blood flow. Therefore, no effect is seen with vasoconstrictor blockage on skin blood flow during exercise except at the onset of exercise.
Brimonidine tartrate ophthalmic solution 0.025% for redness relief: an overview of safety and efficacy
Published in Expert Review of Clinical Pharmacology, 2022
Clinical trials using 0.025% brimonidine tartrate have proven the drug to be relatively safe with little systemic and ocular adverse events. The few adverse events identified included pain upon instillation, irritation, and pruritus, all of which were described to be mild to moderate in severity. However, many of the adverse events of concern, especially those that have limited wider uses of previous generations of vasoconstrictors, such as allergic reaction and tachyphylaxis, are known to occur with a long-term continuous use. The 4-week regimen of the 3 trials introduced in this review may not have been sufficiently long enough to identify all possible side effects. Furthermore, although the drug level was negligible in plasma samples of those topically applying the ophthalmic solution, we cannot entirely rule out the possibility of systemic adverse events. Theoretically, the drug might be able to cross immature or damaged blood–brain barrier such as those with previous history of head trauma, cerebral hemorrhage, or intracranial operations in considerable quantities. The vasoconstrictor may act on vessels systemically to aggravate preexisting vascular conditions such as the Raynaud phenomenon or cerebral aneurysm. Surveys of decongestant users have reported side effects such as headache, chest pain, and palpitations. Long-term studies and market surveys are necessary to confirm that brimonidine does not suffer from the same limitations of its predecessors.
Serum catestatin level is increased in women with preeclampsia
Published in Journal of Obstetrics and Gynaecology, 2022
Nevin Tüten, Onur Güralp, Koray Gök, Kübra Hamzaoglu, Yahya Ozgün Oner, Melike Makul, Huri Bulut, Kübra Irmak, Abdullah Tüten, Eduard Malik
The autonomic nervous system plays an important role in the adaptation of the cardiovascular system to pregnancy (Karumanchi and Granger 2016). During normal pregnancy, vasodilation is seen, and plasma volume increases. An increase in sympathetic activity and a decrease in parasympathetic activity occur to compensate for these changes; these compensation mechanisms revert to their original state after birth (Ekholm et al. 1994; Heiskanen et al. 2008; Jarvis et al. 2012; Shi et al. 2015; Reyes et al. 2018). While the maternal vascular system responds to increased sympathetic activity with vasoconstriction outside of pregnancy, this response becomes obtuse during normal pregnancy, and no vasoconstriction develops (Yang and Clark 1992; Stevens and Lumbers 1995). Beyond the regulation of the autonomic nervous system in normal pregnant women, dysregulation of the autonomic nervous system is seen in preeclamptic pregnancies characterised by increased sympathetic tonus, decreased parasympathetic tonus, and decreased baroreflex (Spradley 2019).