The Journal of thoracic and cardiovascular surgery
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We measured the changes in energy expenditure in the early postoperative phase after coronary artery bypass operations and the ventilatory response to the increased demand for respiratory gas exchange. Breathing pattern and gas exchange were measured noninvasively by respiratory inductive plethysmography and indirect calorimetry with a canopy. Eighteen patients were studied after weaning from mechanical ventilation. ⋯ Arterial carbon dioxide tension increased marginally (37.5 +/- 2.96 mm Hg preoperatively versus 39.7 +/- 4.87 mm Hg postoperatively; p less than 0.05), while oxygen tension decreased from 89.9 +/- 17.3 mm Hg to 62.9 +/- 13.4 mm Hg (p less than 0.001). Minute ventilation increased by 34% in the supine position (p less than 0.01) and by 28% in the half-sitting position (p less than 0.05), while tidal volume remained unchanged. We conclude that coronary artery bypass operations induce hypermetabolism and substantially increase ventilation and risk of arterial hypoxemia during the phase of compromised cardiovascular reserves.
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J. Thorac. Cardiovasc. Surg. · Apr 1991
Cerebral blood flow response to changes in arterial carbon dioxide tension during hypothermic cardiopulmonary bypass in children.
We examined the relationship of changes in partial pressure of carbon dioxide on cerebral blood flow responsiveness in 20 pediatric patients undergoing hypothermic cardiopulmonary bypass. Cerebral blood flow was measured during steady-state hypothermic cardiopulmonary bypass with the use of xenon 133 clearance methodology at two different arterial carbon dioxide tensions. ⋯ Two factors, deep hypothermia (18 degrees to 22 degrees C) and reduced age (less than 1 year), diminished the effect carbon dioxide had on cerebral blood flow responsiveness but did not eliminate it. We conclude that cerebral blood flow remains responsive to changes in arterial carbon dioxide tension during hypothermic cardiopulmonary bypass in infants and children; that is, increasing arterial carbon dioxide tension will independently increase cerebral blood flow.
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J. Thorac. Cardiovasc. Surg. · Apr 1991
Comparative StudySuperior protective effect of low-calcium, magnesium-free potassium cardioplegic solution on ischemic myocardium. Clinical study in comparison with St. Thomas' Hospital solution.
The protective effect of low-calcium, magnesium-free potassium cardioplegic solution on ischemic myocardium has been assessed in adult patients undergoing heart operations. Postreperfusion recovery of cardiac function and electrical activity was evaluated in 34 patients; 16 received low-calcium, magnesium-free potassium cardioplegic solution (group I) and 18 received St. Thomas' Hospital solution, which is enriched with calcium and magnesium (group II). ⋯ Thus low-calcium, magnesium-free potassium cardioplegic solution provided excellent protection of the ischemic heart, whereas St. Thomas' Hospital solution with calcium and magnesium enabled relatively poor functional and electrical recovery of the heart during the early reperfusion period. These results might be related to differing levels of extracellular calcium and magnesium on reperfusion.
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J. Thorac. Cardiovasc. Surg. · Mar 1991
Freehand allograft aortic valve replacement and aortic root replacement. Utility of intraoperative echocardiography and Doppler color flow mapping.
Seventeen consecutive patients undergoing 20 planned aortic valve replacements with allograft valves at Stanford University Medical Center were studied with intraoperative epicardial echocardiography and Doppler color flow mapping before and after cardiopulmonary bypass. Native aortic valves were replaced in 12 of the 20 patients, and eight patients underwent second aortic valve procedures. In 17 of 20 patients allograft selection was guided by prebypass echocardiographic estimates of annular diameter and/or length of allograft aortic root required. Other prebypass findings included unanticipated severe mitral regurgitation in one patient (which precluded allograft aortic valve replacement), left-to-right shunts in five patients, ascending aortic dissection in one, and aortic root disease necessitating coronary reimplantation or bypass in two. Postbypass echocardiography demonstrated acceptable competency of 18 of 19 allograft valves (mild or no aortic insufficiency). Postbypass echocardiography also documented successful repair of four of five shunts and mild mitral regurgitation in 15 of 19 patients (versus 11 of 19 before bypass). ⋯ Intraoperative echocardiography-Doppler mapping is a useful adjunct for allograft aortic valve or aortic root replacement; it allows confident selection of appropriate tissue size before aortic cross clamping, which minimizes delay from allograft thawing procedures. It also provides helpful information about the extent of aortic root disease and coronary ostial anatomy before bypass, confirms allograft competency after bypass, and detects accompanying valvular and other hemodynamic lesions before and after allograft valve replacement.
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J. Thorac. Cardiovasc. Surg. · Mar 1991
Randomized Controlled Trial Comparative Study Clinical TrialThe effect of muscle-sparing versus standard posterolateral thoracotomy on pulmonary function, muscle strength, and postoperative pain.
Increased interest in alternative approaches to thoracotomy has developed because of the considerable morbidity associated with the standard posterolateral technique. We conducted a prospective, randomized, blinded study of 50 consecutive patients to compare postoperative pain, pulmonary function, shoulder strength, and range of shoulder motion between the standard posterolateral and the muscle sparing thoracotomy techniques. Pulmonary function (forced expiratory volume in 1 second and forced vital capacity), shoulder strength, and range of motion were measured preoperatively and at 1 week and 1 month postoperatively. ⋯ Morbidity was identical in the two groups with the exception of postoperative seromas. The prevalence of seroma was 23% in the muscle-sparing group and 0% in the standard incision group (p = 0.0125). We have demonstrated that the muscle-sparing incision may be a reasonable alternative to the standard posterolateral approach.