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Biomedical subjects

K Waxman

Publications and source records attributed to K Waxman.

At least 109 records · Page 6Linked to original sources
PubMed1986

Noninvasive monitoring in emergency resuscitation.

The transcutaneous oxygen (PtcO2) monitoring technique uses a Clark electrode applied noninvasively to the skin surface. To obtain PtcO2 values that respond rapidly to physiologic changes, the electrode is heated to 44 to 45 C. Since its introduction in 1972, the PtcO2 sensor has become standard for monitoring oxygenation of neonates in respiratory distress. However, when applied to critically ill or injured adult patients, PtcO2 values often are much lower than arterial oxygen (PaO2) values. The explanation for this is that PtcO2 reflects not only arterial oxygen tension, but also cardiac output and oxygen delivery. Thus, during low-cardiac-output shock states, PtcO2, values are low, even when PaO2 is normal or high. PtcO2 monitoring in adults thus is useful in assessing oxygen delivery. Comparison to an arterial blood gas can easily differentiate whether a low PtcO2 value might be due to hypoxia or to low cardiac output. Other noninvasive monitors (conjunctival oxygen, pulse oximeter, transcutaneous CO2, end-tidal CO2) also show promise. In the emergency department, PtcO2 monitoring is useful in assessing the presence and severity of shock and hypoxia and as a physiologic monitor for titrating resuscitation.

Emergencies↗
PubMed1986

Invasive cardiorespiratory monitoring.

Several principles should be kept in mind when choosing appropriate monitoring. First, select monitoring devices that provide relevant information on which therapeutic decisions can be made. Second, when alternative, noninvasive monitoring devices are available, use these preferentially because the risk to the patient usually is decreased. Third, when invasive monitoring devices are used, sterile technique and catheter care become extremely important. Fourth, record information that is obtained from monitoring frequently, and titrate therapy continuously based on information generated. Fifth, remove invasive monitoring devices as soon as they are no longer necessary. Finally, when new monitoring approaches are presented, they should be evaluated not only on the basis of their sophistication and cost, but also on the basis of how important will be the new physiologic measurements they provide to improve patient outcome.

Cardiac Output↗
PubMed1985

Calcitonin as a tumor marker for nonthyroid neoplasia.

Plasma levels of calcitonin have been utilized as a tumor marker for medullary carcinoma of the thyroid. Elevated calcitonin levels have been noted with other tumors as well. The present case documents a marked decrease in calcitonin levels following therapy for breast carcinoma, supporting further evaluation of calcitonin as a clinically useful tumor marker for nonthyroid neoplasm.

Breast Neoplasms↗
PubMed1985

Evaluation of possible patient survival in a mock airplane disaster.

A mock disaster at Orange County's John Wayne Airport provided a basis for examining correct triage of patients and their arrival time for definitive care. The ability to triage critically injured patients in a timely fashion was found to be only slightly better than chance routing. For most of the seriously and critically injured patients, it took more than 1.5 hours to reach the hospital. Advanced life support with intravenous fluid resuscitation available on the scene would probably reduce the mortality of possible disaster victims by 50 percent. These problems are presently being addressed. In future disaster exercises, the present type of evaluation could be used to judge improvement in possible patient triage and survival.

Accidents, Aviation↗
PubMed1985

Management of pancreatic and duodenal trauma.

Eighty-four patients were treated for pancreatic or duodenal injuries or both over a 13 year period. Isolated contusion of the duodenum was managed by drainage only, and disruption was managed with primary closure, coverage of the closure with a serosal patch, and drainage. Patients with distal pancreatic injuries that involved the body or tail of the pancreas and were total or near-total transections underwent distal pancreatectomy and splenectomy. The difficult areas of management continue to be the type III and IV pancreatic and duodenal injuries. Extensive pancreatic resection should be reserved for those situations in which the pancreas has been devitalized and it is not expected that resolution will occur with drainage. The mortality in combined severe pancreatic and duodenal injuries was 64 percent with death related to associated injuries in most cases; however, extensive resection (Whipple procedure) in two cases led to death because of leakage from the anastomosis with subsequent retroperitoneal infection. Postoperative management of patients with pancreatic and duodenal injuries should always include careful attention to nutrition.

Abscess↗
PubMed1985

Pulmonary complications after Fluosol administration to patients with life-threatening blood loss.

Fluosol-DA 20% (Fluosol), a perfluorochemical emulsion capable of improving oxygen transport, was used to treat three patients with life-threatening hemorrhage. In each case a decreased partial pressure of oxygen, an increased alveolar-arterial oxygen gradient, fever, an increased white blood cell count, and chest x-ray abnormalities occurred at similar time intervals after treatment with Fluosol. In one patient, pulmonary complications were fatal. Similar adverse reactions to treatment with Fluosol have not been previously reported. Possible explanations for these pulmonary complications are the adult respiratory distress syndrome, oxygen toxicity, or direct toxic effects of Fluosol.

Adult↗
PubMed1985

Laser Doppler velocimetry as a monitor of cardiac output changes in dogs.

Cutaneous blood flow may be measured utilizing a continuous, noninvasive technique, laser Doppler velocimetry (LDV). Monitoring of cutaneous blood flow by LDV might be a useful method to monitor cardiac output. To test this hypothesis, sequential measurements of cardiac output, LDV, and transcutaneous oxygen (PtcO2) were made on 10 anesthetized dogs during experimental shock. There was significant correlation between LDV and cardiac output, while PtcO2 reflected cardiac output only at low flow states. These results show that, in the animal model, cutaneous LDV is a sensitive and specific method for monitoring cardiac output changes.

Animals↗
PubMed1985

Blood and plasma substitutes--plasma expansion and oxygen transport properties.

Because of the risks and costs of blood and blood product infusion, developing blood and plasma substitutes is of significance. Two currently utilized substances, dextran and hydroxyethyl starch, are effective colloid plasma expanders. The dextrans have properties that improve microcirculatory blood flow but are associated with several possible adverse effects. Hydroxyethyl starch is a well-tolerated agent that has efficacy similar to albumin but at a lower cost. Two newer substances, perfluorocarbons and stroma-free hemoglobin, are being developed to improve oxygen transport as well as plasma expansion.

Blood Substitutes↗
PubMed1984

Perfluorocarbon infusion in bleeding patients refusing blood transfusions.

Six severely anemic surgical patients who refused blood products were treated with a perfluorochemical (PFC) emulsion (Fluosol-DA 20%). When these patients received high inspired oxygen concentrations, the emulsion resulted in moderate increases of arterial oxygen content but considerable increases of oxygen consumption, suggesting improved microcirculatory oxygen distribution. The mean +/- SD percentages of consumed oxygen transported by dissolved oxygen in PFC and PFC plus plasma emulsions were 22% +/- 5% and 60% +/- 12%, respectively. Several adverse clinical effects were seen, however, including transient decreases in leukocyte counts, hypotension, and abnormal hepatic and pulmonary function.

Anemia↗
PubMed1984

Development of gallstone pancreatitis. The role of the common channel.

Whether bile reflux through a common channel into the pancreatic duct is a causative factor in the development of gallstone pancreatitis is controversial. To address this issue, we have reviewed a consecutive series of cholecystectomies performed with intraoperative cholangiograms. The cholangiograms and the patients' charts were reviewed independently to determine the incidence of a common channel in patients both with and without pancreatitis and to analyze their clinical courses. The group of patients who had pancreatitis showed a common channel in 19 (90%) of 20 cases, while those patients who did not have pancreatitis showed a common channel in 23 (35%) of 66 cases. The patients who had pancreatitis were less likely to have choledocholithiasis than were those patients who did not have pancreatitis, and these patients were less likely to require exploration of the common bile duct.

Ampulla of Vater↗
PubMed1984

Hypotensive reaction after infusion of a perfluorochemical emulsion.

A hypotensive episode after rapid administration of a perfluorochemical emulsion, Fluosol-DA (20%), was associated with an immediate decrease in systemic vascular resistance but no significant change in pulmonary vascular resistance. Although the physiologic mechanism for this episode is unclear, the clinical implications are significant: the infusion rate of Fluosol-DA should not exceed 10 ml/min.

Adult↗
PubMed1983

Transcutaneous oxygen monitoring of emergency department patients.

Transcutaneous oxygen sensor values reflect peripheral oxygen tensions. During shock and resuscitation, transcutaneous oxygen sensor values depend on peripheral blood flow, and, therefore, reflect cardiac output and oxygen delivery. Transcutaneous oxygen sensor monitoring, therefore, should be quite useful when caring for acutely ill patients; data from 20 surgical emergency department patients support this hypothesis. A normal initial transcutaneous oxygen sensor value of greater than 60 torr, as found in 11 of our patients, implied relatively normal oxygenation and circulation. A low initial transcutaneous oxygen sensor value of less than 60 torr implied deficits of either arterial oxygenation or of perfusion (these can be distinguished by an arterial blood gas determination). In addition, transcutaneous oxygen sensor was useful for continuous monitoring during resuscitation. Successful correction of hypoxia and perfusion deficits results in increased transcutaneous oxygen sensor values. Failure of the transcutaneous oxygen sensor value to increase during resuscitation implies ongoing deficits of tissue oxygenation.

Emergency Service, Hospital↗
PubMed1983

Physiologic determinants of operative survival after portacaval shunt.

Twenty cirrhotic patients with bleeding from esophageal varices were studied before, during, and after portacaval shunt. There were 12 survivors and eight nonsurvivors. Preoperative determination of hepatic function and classification by Child's criteria correctly predicted outcome only in those with very good and those with very poor hepatic function. However, the majority of patients had intermediate liver function, and their operative survival could not be predicted on this basis. Other parameters, however, did distinguish between survivors and nonsurvivors. Survivors had better preoperative cardiac contractility, shorter operations, less severe preoperative and intraoperative blood loss, and fewer emergency operations. Intraoperatively, survivors maintained cardiac index and oxygen delivery while nonsurvivors did not. After operation, survivors had increased cardiac index, oxygen delivery, and oxygen consumption above preoperative values, while nonsurvivors failed to attain this. Analysis of these data suggests that determination of preoperative hepatic function alone will not provide accurate prediction of outcome from portacaval shunt, because there are multiple factors that determine outcome. The determinants identifed in this study were 1) preoperative hepatic function, 2) degree of hemodynamic compensation from preoperative bleeding and shock, 3) magnitude of the intraoperative oxygen deficits, 4) hemodynamic reserve allowing for the compensatory postoperative state, and 5) nutritional status.

Adult↗
PubMed1982

Physiologic responses to massive intraoperative hemorrhage.

In five patients who had massive, sudden, intraoperative hemorrhage, defined as loss of more than 1 L of blood in less than ten minutes, mean arterial pressure was initially maintained, and there were early increases in both systemic and pulmonary vascular resistance; however, cardiac output and oxygen delivery decreased. During control of hemorrhage and replacement of blood, wedge pressure and central venous pressure increased, and mean arterial pressure was maintained; however, cardiac output and oxygen delivery decreased, and oxygen consumption decreased below prehemorrhage levels. Three patients died postoperatively of multiple organ failure. The data indicate that anesthesia and operation affect both cardiopulmonary performance and peripheral oxygen transport, such that the ordinary physiologic response to hemorrhage are lessened. The absence of compensatory increase in oxygen consumption after resuscitation may have contributed to the high postoperative mortality.

Adult↗
PubMed1982

Sequential perioperative lactate determination. Physiological and clinical implications.

Sequential arterial blood lactate concentrations were determined pre-, intra-, and postoperatively in 12 high risk surgical patients. These levels were correlated with simultaneous measurements of arterial blood pressure, cardiac index (CI), and oxygen consumption (VO2). There was a marked increase in lactate values intraoperatively. This increase did not correspond to decreases in either mean arterial pressure (MAP) or CI, but did appear to correlate with decreased intraoperative VO2. Postoperatively, lactate levels remained elevated, and this elevation appeared to correlate with an estimation of intraoperative oxygen deficit. CI and VO2 were increased postoperatively; the data support the hypothesis that these postoperative increases in CI and VO2 represent physiological compensations for intraoperative oxygen deficits. Clinically, determinations of lactate values may prove useful in titrating postoperative therapy to support needed physiological compensations.

Adult↗
PubMed1982

Clinical trial of survivors' cardiorespiratory patterns as therapeutic goals in critically ill postoperative patients.

The hypothesis was tested that the median values of survivors of life-threatening postoperative conditions, rather than the norms of unstressed healthy volunteers, are the appropriate therapeutic goals for critically ill postoperative patients. The authors studied prospectively a series of 100 consecutive critically ill postoperative patients; normal values were used as the therapeutic goals of the control patients, while the median values of survivors were used as the goals of therapy for the protocol group. The age, sex, primary illness, surgical operation, lowest mean arterial pressure (MAP), time in hypotension incidence of severe hypotension (MAP greater than 50 mm Hg), and presence of associated severe medical illnesses (defined by predetermined criteria) were comparable in the control and protocol groups; i.e., clinical conditions of the protocol group were at least as severe as those of the control group. The mortality was significantly less in the protocol group (13%) than in the control group (48%); the number of life-threatening complications were also greater in the control group. These data suggest that the cardiorespiratory pattern of survivors are the appropriate goals of therapy for critically ill patients.

Adult↗