HAeMODYNAMIC EFFECTS OF OXYGEN IN PATIENTS WITH ACUTE MYOCARDIAL INFARCTION

Abstract

Oxygen is frequently given in the treatment of patients with acute myocardial infarction. The hemodynamic changes associated with its administration in this condition have not been defined.The purpose of this study has been to investigate the effect of breathing oxygen on the cardiac output and systemic arterial pressure of patients in the early stages of acute myocardial infarction. SUBJECTS AND METHODSSix male patients aged 47 to 72 years were studied on the first and second day of myocardial infarction.In two of these there were additional studies on the sixth and seventh days. In one patient there was only one study on the tenth day. All had unequivocal evidence of acute myocardial infarction as judged by the clinical history and electrocardiograph. The clinical data are given in Table I.All patients were investigated in a special intensive care unit permanently equipped with apparatus for observation, investigation, and treatment of patients with acute myocardial infarction (Shillingford and Thomas, 1964). Facilities were available for the measurement of cardiac output and intravascular pressures.After clinical assessment, electrocardiography, and chest radiography were completed, polythene catheters (Intramedic U.S.A. PE60) were inserted percutaneously into the brachial artery and an antecubital vein. The venous catheter was advanced so that the tip lay in the superior vena cava. Heart rates were measured from an electrocardiographic tracing over half-minute periods throughout the study and when cardiac output determinations were made. Cardiac output was measured by a dye dilution technique using Coomassie Blue (I.C.I.) as indicator and recording the curve with a photoelectric earpiece (Cambridge Instrument Co.).The first curve was calibrated by equating the height of the tail of the curve three minutes after injection with the amount of indicator in a central venous or arterial blood sample taken at the same time. Dye was extracted from the plasma and measured by spectrophotometry. Subsequent cardiac outputs were calculated according to the areas of the curves (Gabe, Tuckman, and Shillingford, 1962

Does home oxygen therapy (HOT) in addition to standard care reduce disease severity and improve symptoms in people with chronic heart failure? A randomised trial of home oxygen therapy for patients with chronic heart failure

“…Oxygen therapy was associated with a fall in cardiac output and stroke volume, together with a rise in heart rate. 20 The failing heart requires a higher filling pressure. The higher the filling pressure, the worse the cardiac function; hence an intervention causing a rise in filling pressure is deleterious.…”

“…58 Each item is measured on a Likert-type scale from 0 to 3, and seven non-overlapping items make up each of the two subscales. For each of the two continuous subscales (anxiety and depression), patients are categorised as 'normal' (0-7), 'borderline' (8-10) or 'clinically anxious/depressed' (11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21).…”

“…The apnoea-hypopnoea index (AHI) is used to indicate the severity of sleep apnoea and represents the number of apnoea and hypopnoea events per hour of sleep. AHI values are categorised as normal (0-4), mild sleep apnoea (5)(6)(7)(8)(9)(10)(11)(12)(13)(14), moderate sleep apnoea (15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29) and severe sleep apnoea (30+). Considering that both AHI and oxygen saturation can give an overall assessment of the sleep apnoea severity.…”

“…Other evidence for the haemodynamics effects of oxygen is limited to very old studies of small numbers of patients (such as a study of six patients 20 with acute myocardial infarction, in whom 100% oxygen caused a fall in cardiac output). There is no literature suggesting harm from LTOT in patients with CHF.…”

A randomised controlled trial of the effect of high concentration oxygen on myocardial ischaemia during exercise

“…However, there is also substantive evidence to suggest that high concentration oxygen therapy may be harmful when administered to patients with myocardial ischaemia who are not hypoxaemic [7]. Specifically, high concentration oxygen treatment increases coronary vascular resistance and reduces coronary blood flow [3,[8][9][10][11], increases systemic vascular resistance and blood pressure, and reduces cardiac output [12][13][14][15][16][17][18][19]. The magnitude of these physiological responses may be substantial, as illustrated by a recent systematic review and metaanalysis which reported that high concentration oxygen reduces coronary blood flow by 8 to 29% and increases coronary vascular resistance by 22% to 41% [11].…”