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Biomedical subjects

R L Hines

Publications and source records attributed to R L Hines.

8 recordsLinked to original sources
PubMed1990

Pulmonary artery catheters: what's the controversy?

Controversy surrounding the use or misuse of the pulmonary artery catheter (PAC) remains one of the most frequently debated issues in anesthesia, critical care, and cardiology. It has been argued that the cardiovascular data it provides, its ease of insertion, and the low incidence of associated complications mandate its use in all patients undergoing cardiac surgery. Conversely, it has been suggested that clinical experience, combined with information derived from the central venous pressure (CVP) and noninvasive monitors, is adequate to diagnose and treat hemodynamic abnormalities in the perioperative period. A retrospective study addressing the specific issue of patient outcome showed a significant reduction in perioperative reinfarction rates in patients with coronary artery disease undergoing noncardiac surgery compared with historical controls. In another study of patients with left main coronary artery disease undergoing coronary artery bypass grafting (CABG), mortality was decreased from 20.0% to 3.5% in the group monitored with a PAC. In patients undergoing cardiac surgery, data derived from the PAC were shown to be a more sensitive indicator of hemodynamic abnormalities than were "routine" parameters. A definitive assessment of the usefulness of the PAC awaits further investigation.

Cardiac Surgical Procedures↗
PubMed1990

Transesophageal echocardiography: is it for everyone?

Intraoperative use of transesophageal echocardiography (TEE) to detect ischemia is more predictive of a postoperative myocardial infarction than is ECG, and two-dimensional (2-D) TEE has been shown to be more sensitive than ECG in detecting regional wall-motion abnormalities, which are highly suggestive of ischemia. More recent studies have demonstrated that postbypass TEE ischemia is predictive of an adverse outcome. Other potential diagnostic uses of TEE include evaluation and identification of intraoperative ventricular aneurysms and assessment of papillary muscle function. Intraoperative detection of thrombus and atrial myxoma has been significantly enhanced using 2-D TEE and, in the postoperative period, TEE is a more sensitive measure of pericardial tamponade than changes in hemodynamic variables. In cardiac surgery, contrast TEE has been reported to be useful in evaluating the adequacy of the delivery of cardioplegia as well as aiding in the detection of air emboli. The incorporation of Doppler into TEE probes now enhances the clinician's ability to diagnose and treat patients with valvular heart disease. The value of TEE must be weighed against cost-effectiveness and outcome as it becomes more widely used.

Cardiac Surgical Procedures↗
PubMed1990

Management of acute right ventricular failure.

The thin-walled right ventricle compensates poorly for any increase in afterload, and its output abruptly decreases with small elevations in pulmonary vascular resistance. In patients who have acute right ventricular (RV) dysfunction following bypass, it is, therefore, important to maintain pulmonary vascular resistance at normal or reduced levels. The location and movement of the RV septum may have a dramatic impact on RV contraction, and abnormalities of left ventricular function all affect RV function. Inadequate intraoperative protection has also been implicated in impaired RV function, and there is some evidence that caution is required during removal of air from the left side of the heart and resumption of ventilation. Volume expansion, pharmacological intervention, and mechanical devices have all been used successfully in patients with RV failure. Volume loading is the basis of treatment when the pulmonary vascular resistance is normal. When this alone is insufficient, or when pulmonary vascular resistance is elevated, inotropic agents may be useful. Clinical reports have demonstrated that amrinone, a member of the new class of inotropic fraction-III phosphodiesterase inhibitors, is an effective agent for the management of RV dysfunction following bypass. Correction of septal wall dislocation may be achieved with intraaortic balloon pumps.

Acute Disease↗
PubMed1988

The effect of incremental positive end-expiratory pressure on right ventricular hemodynamics and ejection fraction.

The effects of incremental positive end-expiratory pressure (PEEP) on right ventricular (RV) function were evaluated in 36 (n = 36) ventilated patients. Positive end-expiratory pressure was increased from 0 (baseline) to 20 cm H2O in 5-cm H2O increments and RV hemodynamics and thermally derived right ventricular ejection fraction (RVEF), right ventricular end-diastolic volume index (RVEDVI), and right ventricular end-systolic volume index (RVESVI) were computed. Right ventricular contractility was determined from the analysis of RV systolic pressure-volume relations. Right ventricular ejection fraction declined from 42 +/- 8% at baseline to 30 +/- 9% at 20 cm H2O PEEP. Right ventricular end-diastolic volume index declined between 0 and 5 cm H2O PEEP (103 +/- 42 to 92 +/- 34 ml.m-2) and then increased to 113 +/- 40 at 20 cm H2O PEEP. Right ventricular end-systolic volume index increased from 60 +/- 31 ml.m-2 at baseline to 79 +/- 34 ml.m-2 at 20 cm H2O PEEP. The slope (E) of the relation of RV peak systolic pressure to RV end-systolic volume index decreased from 0.26 mm Hg.m2.ml-1 between PEEP of 0-15 cm H2O to 0.05 mm Hg.m2.m-1 at PEEP greater than 15 cm H2O. It is concluded that low levels of PEEP have a predominant preload reducing effect on the RV. Above 15 cm H2O PEEP, RV volumes increase and E decreases, consistent with increased RV afterload and a decline in RV contractility.

Adult↗
PubMed1986

Protamine: does it alter right ventricular function?

Protamine administration has been associated with cardiac decompensation secondary to acute pulmonary vasoconstriction and subsequent right ventricular failure. To determine whether protamine infusion produced alterations in right ventricular performance, we evaluated both right and left ventricular function in patients receiving protamine infusion. The dose of protamine administered was calculated as adequate to reverse heparin as measured by the activated clotting time (ACT). Indices of right and left ventricular function obtained included right atrial pressure, right ventricular pressure, right ventricular ejection fraction, pulmonary artery pressure, pulmonary capillary wedge pressure, cardiac output, blood pressure, and heart rate. These measurements were obtained prior to protamine administration, at 1/2 total protamine dose, at completion of protamine infusion, and prior to sternal closure. No significant changes in right ventricular ejection fraction, right ventricular end-diastolic pressure, mean pulmonary artery pressure, or pulmonary vascular resistance were seen at any point during the study. Left ventricular function remained unchanged. Even in patients who are possibly at an increased risk (pulmonary artery hypertension, PAP greater than 25 mm Hg), no deterioration in right or left ventricular function could be demonstrated following protamine administration. These data suggest that protamine does not consistently exert a significant detrimental effect on right ventricular performance.

Blood Pressure↗
PubMedDate not supplied

The adult respiratory distress syndrome.

The adult respiratory distress syndrome (ARDS) represents a common denominator of acute lung injury leading to alveolar flooding, decreased lung compliance, and altered gas transport. In the absence of specific etiology and therapy, the management of ARDS remains largely supportive. Ubiquitous use of intermittent positive-pressure ventilation with positive end-expiratory pressure (PEEP) improves arterial oxygenation but with some risk of pulmonary barotrauma and decreased cardiac output. The recent understanding of lung inflation as a modulator of right heart afterload and the effect of the right ventricle on global cardiac performance continues to redefine optimal patterns of ventilatory and hemodynamic intervention in ARDS.

Capillary Permeability↗