John J. Osborn

Ruptured aneurysms of the aortic sinuses of Valsalva

Abstract The basic defect of a congenital aneurysm of the aortic sinuses of Valsalva is a lack of continuity between the media of the aorta and the annulus fibrosus of the aortic valve ring. Most of the aneurysms arise in the right and noncoronary cusps and rupture into the right ventricle or right atrium. Rupture of the aneurysm leads to an aorticocardiac fistula which overloads the right heart leading to severe congestive failure. The murmur is usually continuous, loud and superficial and most frequently heard best in the third and fourth intercostal spaces to the left of the sternum. These fistulas and associated defects can be corrected with open heart surgery with a low mortality rate.

THE MANAGEMENT OF ABNORMAL BLEEDING FOLLOWING EXTRACORPOREAL CIRCULATION

Excerpt In the early days of the development of artificial heart-lung machines, abnormal postoperative bleeding was a very frequent phenomenon, and an unmanageable hemorrhagic diathesis is an occas...

An evaluation of computer-based patient monitoring at Pacific Medical Center

Abstract The computer-based patient monitoring system has been in use in the Cardiopulmonary Intensive Care Unit at Pacific Medical Center for 8 years. This paper reports results of a two part objective evaluation of the effectiveness of the system. The first study documented the system utilization by the clinical staff. The average number of interactions per hour and per postoperative hour were determined. The category of information requested and type of user were also tallied. The second statistical study investigated the impact of the monitoring system on morbidity and mortality. The outcome variables consisted of death rates, stay in unit, days on respirator, days with arterial line, number of arterial blood gases and nurse to patient ratio per day. The results showed essentially no difference between the monitored and control groups. A discussion of the problems in evaluating the impact of monitoring systems is included.

Patterns of myocardial oxygen and lactate extraction in patients undergoing cardiopulmonary bypass.

Abstract Forty-nine patients with acquired mitral or aortic valve disease had myocardial oxygen metabolic studies performed during cardiopulmonary bypass and moderate hypothermia. Twenty-two of these also had lactate determinations performed; lactate production was considered indicative of myocardial anaerobiasis. Metabolic data were obtained during specific intraoperative events such as crossclamping of the aorta, unclamping of the aorta with restoration of coronary autoperfusion, initiation of continuous direct coronary perfusion, arrhythmias, electrocardiographically demonstrable ischemia, and ventricular fibrillation and defibrillation. In all cases ECG evidence of ischemia was accompanied by alterations in O 2 extraction patterns and lactate production, but metabolic derangement often continued to be present after the ECG had returned to normal. Ventricular fibrillation occurred more commonly during coronary artery perfusion than during ischemic cardioplegia and was associated with pronounced increases in calculated myocardial oxygen consumption, as well as lactate production. Seventy-five per cent of patients having ischemic cardioplegia induced by intermittent aortic crossclamping had diminished myocardial extraction of O 2 throughout the operative procedure, with associated production of lactate. Seventy-two per cent of patients having continuous direct coronary perfusion showed an increase in myocardial O 2 extraction with concomitant lactate production during bypass. The pattern of either decreased or increased O 2 extraction persisted in any given patient and was felt to be due to operative technique (ischemic cardioplegia versus direct coronary perfusion) rather than to the underlying lesion. Possible mechanisms involved in the two patterns of O 2 extraction, both associated with anaerobiasis, are discussed. It is concluded that, under the operative conditions prevailing during this study, (1) the surface ECG gives a poor indication of myocardial metabolic dysfunction, (2) spontaneous ventricular fibrillation may be detrimental to cardiac function as the increase in myocardial oxygen consumption is not met by an increase in coronary blood flow, (3) intermittent aortic crossclamping might produce derangement in cellular oxidative metabolic processes, and (4) continuous direct coronary artery perfusion does not meet, and is inadequate to meet, myocardial metabolic demands.

Effect of altered ventilation patterns on compliance during cardiopulmonary bypass.

HERE ARE MANY conflicting reports in T the literature regarding the management of lungs during cardiopulmonary bypass. Edmunds and Austenl reported that when lungs were ventilated throughout bypass, the volume-pressure relationships changed insignificantly, but there were marked changes when there was no ventilation. Cartwright’s group2 reports that no decrease in compliance occurs after extracorporeal circulation. Sullivan and coworkers3 reported that with static inflation during total heart-lung bypass averaging 2% hours, there was no significant alteration in the mechanical properties of the lung-thorax system. The work of Blair and associates4 showed either no change or an improvement in elastic properties during cardiopulmonary bypass, but considered it desirable to ventilate the lungs during bypass.

Laboratory and Clinical Studies during Prolonged Partial Extracorporeal Circulation Using the Bramson Membrane Lung

The survival rate, electrolyte changes, hematological changes, arterial gas analysis, and pulmonary compliances in 14 prolonged venovenous perfusions with the Bramson membrane oxygenator are presented. The Bramson membrane oxygenator functioned efficiently. There were two deaths in the series, neither attributable to the perfusion. Arterial gas studies and pulmonary compliance studies indicated no measurable detrimental effect on the lungs. Platelet counts decreased and white blood cell counts increased during perfusion. A clinical prolonged veno-venous perfusion is reported.

Alarms in an intensive care unit: an interim compromise

Abstract A cardiovascular alarm system formed part of an on-line real-time computer based physiological monitoring and measuring system in a post cardiac surgical intensive care unit. The incidences of false alarms was, as with other monitoring apparatus, disturbing. A detailed analysis of the causes in a clinical situation was carried out. This instanced their frequency, and confirmed that all arose at patient or patient-sensor interface levels. A postulate which might eliminate most of these was devised, and its feasibility tested over an extended period by a second detailed study. As a result, an alarm is now only sounded in response to coexistent changes in both heart rate and vascular pressure. The rationale of this scheme is considered. The compromise, while of limited usefulness, appears to offer practical advantages in the application of automated monitoring.

Bronchopulmonary precapillary blood flow during cardiopulmonary bypass.

Abstract A method of calculating the blood flow traversing bronchopulmonary anastomoses during cardiopulmonary bypass is presented, based on the CO 2 Fick principle. A total of 23 patients have been studied. Bronchial-alveolar flow varied with the type of cardiac lesion, and was often considerable, amounting to 11 per cent of the circulation in one patient with tetralogy of Fallot.

Experience with Perfusion Hypothermia Using an Improved Rotating Disc Oxygenator

Cooling the living organism slows the rate of the metabolic processes. Bigelow, Lindsay, and Greenwood (1950) showed that one effect of hypothermia was that an animal would survive for a longer period when deprived of its circulation. For the first time, therefore, it became possible to shut off the circulation completely, open one of the chambers of the heart, and repair certain intracardiac abnormalities (Lewis, Varco, and Taufic, 1954; Swan, Zeavin, and Blount, 1953). Serious obstacles were soon met when attempts were made to extend the application of this principle in the treatment of more complicated defects. If the surgeon required more than eight or 10 minutes of circulatory occlusion, he found himself sailing between Scylla and Charybdis, for prolonging the period of circulatory occlusion resulted in permanent damage to the central nervous system and further lowering of the temperature inevitably caused ventricular fibrillation. A wealth of time and effort has been spent in trying to overcome fibrillation associated with hypothermia, but, although a new ray of hope appears every few months, there is still no certain method of preventing it. Thus the early promise of hypothermia was not immediately fulfilled, and attention continued to be focused on the development of extracorporeal circulation. In the past five years the pioneering work of Miller, Gibbon, and Fineberg (1953) and many others has gone forward on many fronts, resulting in the development of cardiopulmonary bypass systems which are highly efficient and which carry minimal risk to the patient when employed by expert teams. And yet the enthusiasts of hypothermia were not idle. The direct attack on ventricular fibrillation had failed for the moment, but recently an outfilanking manceuvre has made it possible to deal with this hazard. The heart was apparently the weak link in

The use of the digital computer in the study of patients during exercise-induced stress☆

Abstract A computer analysis technique of monitoring and measuring an individuals cardiovascular and respiratory responses to exercise has been described in detail. The proper use of this procedure yields significant data reflecting the hemodynamic status of subjects with various degrees of cardiovascular and respiratory impairment.