Hypotension definition

Colledge NR, Wilson 1A, Macintyre CC et al. (1994) The prevalence and characteristics of dizziness in an elderly community. Age Ageing 23(2) 117-120 The Consensus Committee of the American Autonomic Society and the American Academy of Neurology. (1996) Consensus statement on the definition of orthostatic hypotension, pure autonomic failure, and multiple system atrophy. Neurology 46(5) 1470 Cooper C, Atkinson El, lacobsen SI et al. (1993) Population-based study of survival after osteoporotic fractures. Am 1 Epidemiol 137(9) 1001-1005 Cummings SR and Melton LI (2002) Epidemiology and outcomes of osteoporotic fractures. Lancet 359(9319) 1761-1767... 

One pharmacological theory of the mechanism underlying postural hypotension is the false-transmitter theory. Tyramine may be metabolized to an inactive metabolite (octopamine) that partially fills the NE storage vesicles with a false (inactive) transmitter, but definitive proof is lacking. 

The possibility that talc can cause respiratory failure was explored further in 1997 (24). ARDS occurred in four of 338 patients treated with talc poudrage (2 g) via thoracoscopy. All four had mahgnant effusions and aU developed bilateral pulmonary infiltrates, hjrpoxia, and hypotension within 24—48 hours of talc insufflation. All four required mechanical ventilation and three died. Bronchoalveolar lavage was performed in all four and talc crystals were recovered from lavage fluid in each case. Furthermore, at autopsy in one patient, talc crystals were found in almost every organ, showing that systemic distribution of talc did occur after pleurodesis. However, as the authors acknowledged, it was not possible to definitely attribute the symptoms in these patients to the talc pleurodesis. Studies in animals have shown systemic distribution of talc after pleurodesis (25). However, systemic dissemination may occur in all patients treated with pleurodesis and does not confirm that this is the cause of respiratory failure documented in a small number of patients. 

Another issue relating to dialysis membranes is their ability to stimulate the immune system. If the dialysis filter membrane does not activate the complement system (C3a and C5a) when it comes in contact with the patient s blood, it is considered biocompatible. In the acute setting, the incidence of hypotension, fever, bronchoconstric-tion, and thrombocytopenia are lower in patients dialyzed with biocompatible filters. The most biocompatible dialyzers use a synthetic membrane of PS, PAN, or PMMA. Although not definitive, biocompatible membranes may be associated with fewer adverse events during dialysis, lower rates of hospitalization, reduced death rates, and slower declines in residual renal function. ... 

A plethora of substances are normally employed to lower the blood pressure, though their efiect may be transient. A few of them are used for their hypotensive action. An arbitrary definition of normal adult blood pressme afforded by the World Health Organization (WHO)- is a systolic pressnre eqnal to or below 140 mm Hg together with a diastolic pressnre equal to or below 90 mm Hg. ... 

Vasicinone (29), the autooxidation product of vasicine, produces definite bronchodilatation against histamine-induced bronchospasm, slight hypotension, and a positive inotropic action with increased coronary flow 152,156,183,185). Prakash et al. 140) postulated that the combination of sympathomimetic amines and vasicinone in some Sida species would account for their major therapeutic uses in the Indian system of medicine, for example, in the treatment of asthma and other chest ailments. Vasicinone has been used as a model for the development of the expectorant 2-amino-3,5-dibromo-jV-cyclohexyTV-methylbenzene-methanamine. 

Amin et al. have observed that vasicinone, an auto-oxidation product of vasicine from extracts of A. vasica leaves, causes definite bronchodilation in the presence of histamine-induced bronchospasm, slight hypotension and a positive cardiac inotropic action with increased coronary flow. The investigators attribute the bronchodilator effect of vasaka leaves to the small amount of vasicinone produced by auto-oxidation of vasicine (cited after 124). Mehta et al. (136) have isolated 1-vasicinone from A. vasica and demonstrated that it is not an artifact as it has bronchodilator activity in contrast to the bronchoconstrictor activity of 1-vasicine. 

Consensus Committee of the American Autonomic Society and the American Academy of Neurology on the definition of orthostatic hypotension, pure autonomic failure and multiple system atrophy. Neurology 46, 1470-1471 (1996). 

Observational studies Along with efficacy, toxicity of IL-21 was evaluated in a multicenter phase II study of patients with metastatic melanoma. Adverse events seen in more than 20% of patients included fever, fatigue, rigors, rash and pruritus. Seven of the 40 patients (17.5%) experienced hypotension with six grade II reactions requiring intravenous fluids. Three serious reactions, each grade 4, possibly/probably/definitely related to IL-21 were one case of neutropenia and two patients with increases in liver enzymes associated with progressive liver metastases [65 ]. 

Aronski et al. (45 ) studied systolic time intervals and peripheral blood flow in 12 patients after induction of anaesthesia with 0.05 ml/kg body weight Althesin and concluded that the drug has a definite cardio-depressive action. In another series of 220 patients (46 ) tachycardia and hypotension were seen in 35 and 25% of cases respectively. The respiratory depressant effect of the drug was related to the speed of injection. Muscle tremors were absent when Althesin was given by intravenous infusion. Even convulsions after Althesin have been described, immediately after the injection (4 C) or, in the case of less rapid injection, after some delay (48C). The slow injection of Althesin can indeed reduce the incidence of aU its side effects, as was shown in a comparison between 2 groups of 30 patients in which differing rates of administration were employed (49C). 

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