Could diuretics in hypoxic states be bad for the pulmonary circulation?
1997; Elsevier BV; Volume: 349; Issue: 9069 Linguagem: Inglês
10.1016/s0140-6736(05)63873-1
ISSN1474-547X
Autores Tópico(s)Cardiac Arrest and Resuscitation
ResumoThe maintenance of ventilation-perfusion ratios in the gas-exchange units of the lung is the major determinant of normoxaemia. Vasoconstriction in the pulmonary vasculature in response to hypoxia is a local homoeostatic mechanism that diverts blood away from hypoxic areas to ensure matching of ventilation with perfusion. The fundamental importance of this mechanism is emphasised by its presence in a range of animal species. In chronic obstructive pulmonary disease (COPD) hypoxia-induced pulmonary vasoconstriction may work to the disadvantage of the host in that chronic hypoxia leads to a sustained rise in pulmonary artery pressure, vascular remodelling, and ultimately impairment of right ventricular function, leading to cor pulmonale. 1 Fishman AP Hypoxia on the pulmonary circulation: how and where it acts. Circ Res. 1976; 38: 221-231 Crossref PubMed Scopus (354) Google Scholar , 2 Klinger JR Hill NS Right ventricular dysfunction in chronic obstructive pulmonary disease: evaluation and management. Chest. 1991; 99: 715-723 Crossref PubMed Scopus (84) Google Scholar In addition to the local effect of hypoxia on pulmonary vessels, such patients show activation of the renin-angiotensin system, with raised concentrations of angiotensin II, which can also act as a direct pulmonary vasoconstrictor. 3 Farber MO Roberts LR Weinberger MH Robertson G Fineberg NS Manfredi F Abnormalities of sodium and water handling in chronic obstructive lung disease. Intern Med. 1982; 142: 1326-1330 Google Scholar , 4 Lipworth BJ Dagg KD Vasoconstrictor effects of angiotensin II on the pulmonary vascular bed. Chest. 1994; 105: 1360-1364 Crossref PubMed Scopus (45) Google Scholar It has also been suggested that angiotensin II may indirectly facilitate pulmonary vasoconstriction due to hypoxia.
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