PubMed Health⌕ Search

Biomedical subjects

W C Shoemaker

Publications and source records attributed to W C Shoemaker.

At least 127 records · Page 7Linked to original sources
PubMed1988

Clinical use of nonautologous fibrin glue.

Nonautologous, highly concentrated human fibrinogen and clotting factors were used in the form of fibrin glue to treat three patients with varied surgical problems that were resistant to conventional treatment. Fibrin glue was used to occlude longstanding enterocutaneous fistulae, control liver hemorrhage in an alcoholic patient with coagulopathy, and perform a splenorrhaphy, following a gunshot wound to the spleen. Fibrin glue is effective in establishing hemostasis and sealing tissues; its use is a helpful adjunct in the care of surgical patients.

Adult↗
PubMed1987

Relation of oxygen transport patterns to the pathophysiology and therapy of shock states.

Descriptions of the sequence of hemodynamic and oxygen transport events have characterized the various types of shock syndromes and have shown that reduced VO2 is the earliest pathophysiologic event; it precedes the initial hypotensive crisis. Reduced or inadequate VO2, produced by low flow, by maldistribution of flow, and by increased metabolic demand is the primary pathogenic event that produces the shock state as well as the regulatory mechanism that stimulates compensatory reactions including increases in heart rate, myocardial contractility, cardiac output and minute ventilation. Sequential hemodynamic and oxygen transport patterns are related to the degree of the shock state and its outcome; the patterns of survivors and nonsurvivors can be predicted from these patterns by multivariate analyses. A branch chain decision tree for fluid resuscitation of critically ill postoperative patients was developed from decision rules based on objective, physiologic, heuristic data of survivors. Criteria were defined for initiating and stopping fluids, inotropic agents, vasodilators and vasopressors; colloids were found empirically to be more effective than crystalloids in reaching the optimal hemodynamic and oxygen transport goals. The use of a branch chain decision tree helps to achieve expeditiously therapeutic goals by providing a coherent organized patient management plan. In prospective studies, therapy that supports compensatory increases in CI and DO2 produces the survivor pattern and was demonstrated to improve survival rates. This confirms the validity of an organized physiologic approach in contrast to the traditional approach whose objectives are to search for physiologic and biochemical abnormalities and then to restore them to normal if and when they are discovered. This approach emphasizes aggressive fluid management in tacit acknowledgement that unrecognizes hypovolemia, delay in treatment of hypovolemia or inadequate volume therapy all lead to low VO2 which is the primary precipitating event in most patients with postoperative, hemorrhagic, traumatic and septic shock. The essence of this plan is to maintain prophylactically the patient in an optimal hemodynamic state that does not allow him to develop tissue hypoxia from blood volume, hemodynamic and oxygen transport deficits. However, episodes of reduced CI, DO2 and VO2 often occur intraoperatively with little or no hypotension or with hypotension which is treated by administration of ephedrine or other vasopressors.

Blood Circulation↗
PubMed1987

Clinical and radiographic indications for aortography in blunt chest trauma.

To determine which clinical and radiographic findings are valuable in selecting patients with blunt chest trauma for aortography, we analyzed the medical records and admission chest radiographs of 76 consecutive victims of blunt chest trauma with suspected thoracic aortic rupture during the past 7 years. All patients were evaluated by history, physical examination, chest radiography, and aortography; a total of 70 clinical and radiographic findings were independently assessed in each patient. The following occurred with significantly greater frequency in patients with thoracic aortic rupture than in those without: history of significant hypotension (mean arterial pressure less than 80 mm Hg) (p less than 0.04); the presence of upper extremity hypertension, bilateral lower extremity pulse pulse deficits, or an initial chest tube output greater than 750 ml of blood (p less than 0.05); and greater incidence of myocardial contusions, intra-abdominal injuries, and pelvic fractures compared with patients without thoracic aortic rupture (p less than 0.05). Mediastinal widening (equal to or greater than 8 cm) shown on anteroposterior chest radiography occurred in all patients with thoracic aortic rupture; however, its specificity was only 10.6%. Radiographic signs that were helpful in indicating the presence of thoracic aortic rupture included paratracheal stripe greater than 5 mm, rightward deviation of the nasogastric tube or central venous pressure line, blurring of the aortic knob, and an abnormal or absent paraspinous stripe. Upper rib fractures and mediastinal to thoracic cage width ratios at any level did not increase diagnostic accuracy for thoracic aortic rupture in the present series. Six patients in the series died, two of whom had thoracic aortic rupture.(ABSTRACT TRUNCATED AT 250 WORDS)

Accidents, Traffic↗
PubMed1987

Effects of blood volume and discontinuance of ventilation on pulmonary vascular pressures and blood gases in patients with low levels of positive end-expiratory pressure.

Hypervolemic, normovolemic and hypovolemic patients with PEEP values less than 10 cm H2O were studied during brief discontinuance of mechanical ventilation to determine whether blood volume status would affect on-off ventilator pulmonary artery pressure (PAP) readings. There were no appreciable hemodynamic effects in patients with blood volume deficits less than one liter. Discontinuance for 1 min decreased PaO2 from 121 +/- 8 (SD) to 77 +/- 7 torr (p less than .001) and increased PaCO2 from 32 +/- 1 to 35 +/- 1 torr (p less than .01). The decreased PaO2 persisted up to one hour after return to mechanical ventilation. Our data reveal that brief discontinuance of ventilation in the normovolemic or hypervolemic patient with physiologic levels of PEEP does not increase the accuracy of PAP measurements. However, with severe hypovolemia, marked reductions in PAP may occur with discontinuance of mechanical ventilation. The practice of recording PAP off the ventilator and frequent suctioning of patients should be abandoned when interruption of mechanical ventilation has little utility and can result in persistent hypoxemia.

Adolescent↗
PubMed1987

Circulatory mechanisms of shock and their mediators.

Traditional concepts of shock therapy have been based on conventional monitoring. However, the availability of invasive monitoring systems has provided the means to describe the patterns of oxygen transport in various acute life-threatening illnesses. Surgical trauma provides a useful model for investigation of other shock syndromes, because measurements may be made in the preoperative control period, during the hemodynamic crisis intraoperatively, and sequentially throughout the postoperative period for survivors and nonsurvivors. This provides a time-related pattern of physiologic events that may form the basis for the physiologic evaluation of mechanisms operative in survivors and nonsurvivors. Physiologic alterations which are compensatory may be identified from the survivor pattern and differentiated from decompensations associated with the lethal course. The DO2 pattern reflects circulatory functional changes which may limit body metabolism as reflected by VO2. The body compensates for tissue hypoxia and increased metabolic needs by increased flow and DO2 in sepsis and trauma, and by increased oxygen extraction in hemorrhagic and cardiogenic shock where flow is limited. The interactions of survivors' hemodynamic and oxygen transport patterns define compensatory responses which primarily are increased cardiac output, DO2, and VO2. Inadequate compensations and decompensations of shock are clearly manifest by the nonsurvivor pattern. Therapeutic goals may be defined by the values of the survivor patterns; reduced mortality and morbidity result when these goals are vigorously applied prospectively (17-19).

Blood Circulation↗
PubMed1987

Pathophysiology, monitoring, outcome prediction, and therapy of shock states.

The time course of hemodynamic and oxygen transport patterns of survivors and nonsurvivors of high-risk critical illness patients was used to evaluate pathophysiologic mechanisms, develop outcome predictors, and propose therapeutic goals. The predictors and goals were tested prospectively and resulted in significantly reduced mortality and morbidity.

Critical Care↗
PubMed1987

Determination of optimal positive end-expiratory pressure by means of conjunctival oximetry.

A method for determining the optimal level of positive end-expiratory pressure (PEEP) by means of noninvasive conjunctival oxygen (PcjO2) monitoring and arterial blood gas analysis was developed from the pattern of changes in PcjO2 tension, invasive hemodynamic parameters, and oxygen transport variables during PEEP titration in a series of patients with adult respiratory distress syndrome. All patients had radial and pulmonary artery (PA) catheters inserted and blood volume was measured with 125I serum albumin before each study. During progressive increases in the level of PEEP, PcjO2 tensions reflected changes in both PaO2 and cardiac index (CI), depending on whether PEEP produced a significant decrease in CI. In patients with a stable CI, PcjO2 tensions tracked PaO2 values (rw = 0.92); in patients with a greater than a 15% decrease in CI, the conjunctival index, CjI (defined as the PcjO2/PaO2 ratio), tracked CI (rw = 0.87), excluding one patient with high cardiac output-septic shock and severe hypoxemia. PcjO2 correlated with PaO2 in the latter patient (r = 0.99) probably because conjunctival oxygen transport was limited by arterial oxygen content (PaO2 = 34 torr) rather than blood flow (CI greater than 6 L/min X m2). In patients with a greater than a 10% decrease in CI as a result of PEEP, the greater the decrease in CI, the better CjI values correlated with CI. We conclude that PcjO2 monitoring combined with repeated arterial blood gas analysis may be used to titrate PEEP therapy in patients with adult respiratory distress syndrome. In patients whose CjI significantly decreases because of PEEP, PA catheterization and measurement of cardiac output are indicated because of the likelihood of a significant (greater than 15%) decrease in CI. In the absence of a significant decrease in the CjI, optimum PEEP occurs at the level producing maximum PcjO2. It is hoped that by following the described algorithm, many patients will be spared the cost and morbidity of unnecessary PA catheterization.

Adult↗
PubMed1986

Noninvasive conjunctival oxygen monitoring during carotid endarterectomy.

Conjunctival oxygen tension (PcjO2) was measured continuously during carotid endarterectomy in 15 patients to evaluate its sensitivity in patients receiving shunts. These studies suggest that PcjO2 tracks brain perfusion during periods of carotid artery occlusion. Reduced PcjO2 was clearly demonstrated with systemic hypotension, carotid artery clamping, and carotid shunt obstruction and clamping. Monitoring of PcjO2 is noninvasive, easy to perform, offers no danger to the patient, and allows real-time assessment of the local tissue perfusion. It provides valuable information on the effectiveness of carotid oxygen transport and, in conjunction with arterial blood gas values, expresses carotid artery perfusion relative to systemic oxygen transport. Further investigations using the PcjO2 sensor may define criteria for intraoperative carotid arterial shunting in patients with tenuous cerebral perfusion, and for prompt intervention in patients with deteriorating perfusion prior to the onset of life-threatening cerebral ischemia.

Aged↗
PubMed1986

Resuscitation of the trauma patient: restoration of hemodynamic functions using clinical algorithms.

Two algorithms were developed for immediate fluid resuscitation and subsequent management of emergency trauma patients and critically ill postoperative patients. These algorithms were developed from decision rules based on objective physiologic values attained in patients surviving life-threatening shock and trauma. The improved mortality in prospective studies of these two algorithms supports the hypothesis that compensatory physiologic responses of survivors of life-threatening acute illness are major determinants of outcome. Therapy that supports these compensations and produces the survivor pattern was found to improve survival rates and reduce post-resuscitation complications. These prospective studies confirm the validity of an organized, coherent physiologic approach that has as its goal the achievement of optimal physiologic patterns in contrast to simple restoration of hemodynamic and chemical abnormalities to the normal range, as has been the endpoint of the traditional approach.

Adult↗
PubMed1986

Assessment of intestinal and renal perfusion using surface oximetry.

Using a miniaturized polarographic oxygen sensor, we studied the sequential effects of graded hypoxia and standardized hemorrhagic shock on organ surface oxygen tension (PsO2) measurements obtained from the canine small intestine and kidney. During hypoxia, intestinal and renal PsO2 values decreased along with PaO2. The weighted mean correlation coefficients for intestinal and renal PsO2 vs. PaO2 were 0.94 and 0.98, respectively. During severe hypoxia, intestinal and renal PsO2 values fell by 55 +/- 8% and 55 +/- 7% (SEM), respectively, while oxygen delivery fell by 58 +/- 10% (SEM). During active hemorrhage, intestinal and renal PsO2 values decreased along with cardiac output, while PaO2 remained relatively constant. Intestinal and renal PsO2 values correlated with cardiac output during hemorrhage and reinfusion of the shed blood. Initially, intestinal PsO2 values fell more quickly than did renal PsO2; the latter decreased by approximately half as much as intestinal PsO2 after 15 and 30 ml/kg of blood loss. After a 45-ml/kg blood loss, however, the decreases in intestinal and renal PsO2 values were not significantly different from each other. During the terminal stage, cardiac output declined progressively, as did intestinal and renal PsO2 values, despite a relatively high PaO2. Overall, intestinal and renal PsO2 values tracked PaO2 during hypoxia, cardiac output during hemorrhage and reinfusion, and oxygen delivery during both conditions. Clinical and experimental experience indicates that organ PsO2 monitoring is potentially valuable for the intraoperative assessment of tissue perfusion and viability.

Animals↗
PubMed1986

Comparison of measurements of cardiac output by bioimpedance and thermodilution in severely ill surgical patients.

In order to evaluate a new thoracic electrical bioimpedance (TEB) system for measurement of stroke volume based on the Sramek-Bernstein equation, 391 paired values of cardiac output were measured simultaneously with the standard thermodilution method. These values were obtained from 16 patients selected for having the most severe illness during a 6-month period; the intent was to evaluate the bioimpedance method in the worst possible situations. The correlation coefficient (r) was 0.83, slope was 0.87, intercept was 1.53, and the mean difference between the two methods was 16.2 +/- 11.8 (SD)% in the total series. In 285 paired samples where satisfactory conditions were met, r was 0.90, slope was 0.98, intercept was 0.34, and the mean difference was 11.8 +/- 8.9%. The data indicate satisfactory correlations between these two methods. When the TEB waveform is satisfactory, the agreement between TEB and thermodilution is as good as the agreement between serial thermodilution methods. Difficulties may arise with dysrhythmias, tachycardia (heart rate greater than 150 beat/min), metal in the chest or chest wall, sepsis, hypertension, and extremely oily skin. Mechanical ventilation did not appear to be a problem.

Cardiac Output↗
PubMed1986

Hemodynamic and oxygen transport effects of dobutamine in critically ill general surgical patients.

The effects of dobutamine on hemodynamic and oxygen transport were evaluated in 43 studies on 34 critically ill general (noncardiac) surgical patients. Dobutamine, beginning at a low dose (2.5 micrograms/kg X min) significantly increased cardiac index (CI), oxygen delivery (DO2), and oxygen consumption (VO2), while decreasing mean arterial pressure, pulmonary artery and wedge pressures, and systemic and pulmonary vascular resistances; blood gases, pH, and pulmonary shunt were not significantly changed. These effects were seen in postoperative and septic patients, as well as in patients with normal, low, and high control CI. These responses were poor in terminally ill and hypovolemic patients; however, when the latter were given additional fluids, their responses were markedly improved. The hemodynamic effects of dobutamine are well known, but the DO2 and VO2 effects, which suggest improved tissue perfusion, have not been appreciated.

Adolescent↗
PubMed1986

[Reactions of critically ill patients to volume therapy with hydroxyethyl starch (6% HES 450/0.7)].

At 31 critically ill surgical patients who on clinical grounds required fluid therapy, hemodynamic and oxygen transport, responses were measured after volume expansion with 500 ml 6% HES 450/0,7. There were statistically significant increases in cardiac index (CI) from 3,5 +/- 2,1 to maximal values of 4,4 +/- 0,2 (l/min/m2) and in wedge pressure (WP) from 9,3 +/- 0,7 to maximal values of 13,6 +/- 0,8 (mm Hg) and a significant reduction of systemic vascular resistance index (SVRI) from 2018 +/- 128 to 1641 +/- 102 (dynsec/cm5 m2). There were also observed statistically significant maximal increases of left ventricular stroke work index (LVSWI) from 41 +/- 3,1 to 53 +/- 3,2 (gm/m2) of oxygen delivery (DO2) from 489 +/- 24 to 587 +/- 29 (ml/min/m2) and of oxygen consumption (VO2) from 111 +/- 6 to 130 +/- 7 (ml/min/m2) which took place at the time of the maximum CI-increase. Moreover MAP-, CI- and VO2-responses of patients were stratified according to clinical conditions like time of operation, age, prognosis, ARDS, sepsis, hyperdynamic- and blood volume status.

Adult↗
PubMed1986

Effects of prostaglandin E1 in adult respiratory distress syndrome.

Prostaglandin E1 (PGE1, Prostin VR) in doses of 30 ng/kg . min was studied in two series of severely ill surgical patients with adult respiratory distress syndrome (ARDS). First the drug was administered in an initial trial in six patients; then a prospective, randomized, blinded trial was conducted in 10 studies on nine patients. PGE1 markedly decreased pulmonary artery pressure, pulmonary and systemic vascular resistance indexed, and venous pressures, while increasing cardiac output, arterial PO2 (PaO2), oxygen delivery, and oxygen consumption when compared with the baseline preinfusion control values and with the response of the placebo-treated control series. The PGE1 responses were greater in patients whose ARDS was primarily attributed to the postoperative state with or without sepsis and least in patients with cirrhosis. The data are consistent with the concept that the drug reduces vasoconstriction primarily in the pulmonary circulation but also in the systemic circulation; improved PaO2 usually follows the hemodynamic effect. We conclude that PGE1 may be a useful adjunctive therapy for ARDS.

Adult↗