Biomedical subjects
Publications and source records attributed to R A Balk.
Fiberoptic bronchoscopy is a valuable tool in the intensive care unit. The procedure may be an integral part of airway management and has diagnostic and treatment capabilities. Demonstrated expertise is necessary to perform the procedure safely and effectively. This expertise may be particularly important when faced with a complex patient who presents with airway management problems or significant hemoptysis.
OBJECTIVE: To evaluate the safety and potential efficacy of aerosolized surfactant in intubated patients with adult respiratory distress syndrome (ARDS). DESIGN: A prospective, double-blind, placebo-controlled, randomized, parallel, multicenter pilot clinical trial. PATIENTS: A total of 51 patients with sepsis-induced ARDS were entered into the study within 18 hours of developing sepsis or sepsis syndrome. INTERVENTION: Patients were randomized into four treatment groups in a 2:1:2:1 ratio, as follows: 12 hours of surfactant per day, 12 hours of 0.6% saline per day, 24 hours of surfactant per day, and 24 hours of 0.6% saline per day. Surfactant or saline was aerosolized continuously for up to 5 days using an in-line nebulizer that aerosolized only during inspiration. MAIN OUTCOME MEASURES: Ventilatory data, arterial blood gases, and hemodynamic parameters were measured at baseline, every 4 or 8 hours during the 5 days of treatment, 24 hours after treatment, and 30 days after treatment, at which time mortality was also assessed. Safety was evaluated throughout the 30 days of the study. RESULTS: Surfactant was administered safely in ventilated patients when given continuously throughout the 5 days using the nebulizer system. Although there were no differences in any physiological parameters between the treatment groups, there was a dose-dependent trend in reduction of mortality from 47% in the combined placebo group to 41% and 35% in the groups treated with 12 hours and 24 hours of surfactant per day, respectively. CONCLUSIONS: Aerosolized surfactant was well tolerated when administered on a continuous basis for up to 5 days; however, at the doses given, it did not result in significant improvements in patients with sepsis-induced ARDS.
OBJECTIVE: To further define the safety and efficacy of recombinant human interleukin 1 receptor antagonist (rhIL-1ra) in the treatment of sepsis syndrome. STUDY DESIGN: Randomized, double-blind, placebo-controlled, multicenter, multinational clinical trial. POPULATION: A total of 893 patients with sepsis syndrome received an intravenous loading dose of rhIL-1ra, 100 mg, or placebo followed by a continuous 72-hour intravenous infusion of rhIL-1ra (1.0 or 2.0 mg/kg per hour) or placebo. OUTCOME MEASURE: Twenty-eight-day all-cause mortality. RESULTS: There was not a significant increase in survival time for rhIL-1ra treatment compared with placebo among all patients who received the study medication (n = 893; generalized Wilcoxon statistic, P = .22) or among patients with shock at study entry (n = 713; generalized Wilcoxon statistic, P = .23), the two primary efficacy analyses specified a priori for this trial. Results from secondary analyses suggest an increase in survival time with rhIL-1ra treatment among patients with dysfunction of one or more organs (n = 563; linear dose-response, P = .009). Retrospective analysis demonstrated an increase in survival time with rhIL-1ra treatment among patients with a predicted risk of mortality of 24% or greater (n = 580; linear dose-response, P = .005) as well as among patients with both dysfunction of one or more organs and a predicted risk of mortality of 24% or greater (n = 411; linear dose-response, P = .002). CONCLUSIONS: There was not a statistically significant increase in survival time for rhIL-1ra treatment compared with placebo among all patients who received the study medication or among patients with shock at study entry. Secondary and retrospective analyses of efficacy suggest that treatment with rhIL-1ra results in a dose-related increase in survival time among patients with sepsis who have organ dysfunction and/or a predicted risk of mortality of 24% or greater.
The hemodynamic alterations in elderly individuals when combined with their reduced functional capacity concerning specific organ systems places them at an increased risk of developing shock with certain disease processes. The initial management should be directed toward shock resuscitation with appropriate volume and/or vasopressor/inotropic support. Then attention must be given to identifying and treating the underlying causes and the pathophysiologic mechanisms involved in the shock. Monitoring the adequacy of the treatment is important and can be done by sequential measurement of various parameters such as O2 delivery, O2 consumption, lactate levels, and gastric intramucosal pH.
OBJECTIVE: To determine whether plasma tumor necrosis factor-alpha (TNF-alpha), interleukin-1 beta (IL-1 beta), interleukin-6 (IL-6), and lipopolysaccharide are detectable in patients when they first present with the sepsis syndrome and to determine whether levels correlate with patient survival. DESIGN: Prospective study comparing patients with the sepsis syndrome, critically ill patients without sepsis, and normal healthy volunteers. SETTING: Tertiary care hospital affiliated with a medical school. PATIENTS: The study included 97 consecutive patients on a medical service who met the criteria for the sepsis syndrome; 20 critically ill patients without sepsis who were in the medical intensive care unit; and 20 healthy volunteers who served as comparison groups. MEASUREMENTS: Plasma tumor necrosis factor-alpha, IL-1 beta, interleukin-6, and endotoxin (lipopolysaccharide) levels were measured when a patient was first identified as having the sepsis syndrome. Survival was defined as being alive 30 days after the sepsis syndrome was diagnosed. RESULTS: Fifty-four percent of patients with the sepsis syndrome had detectable levels of TNF-alpha (median, 26 pg/mL; range, nondetectable to 1000 pg/mL); 37% had detectable levels of IL-1 (median, 20 pg/mL; range, nondetectable to 2850 pg/mL); 80% had detectable levels of IL-6 (median, 415 pg/mL; range, nondetectable to 2380 pg/mL); and 89% had detectable levels of lipopolysaccharide (median, 2.6; range, nondetectable to 12.5 endotoxin units [EU]/mL). In all cases levels were higher than those in critically ill patients without sepsis and normal healthy controls (P < 0.001 for all comparisons). Plasma levels of TNF-alpha, IL-1 beta, IL-6, and lipopolysaccharide were detectable in patients regardless of culture status. The IL-6 level was 69% (95% CI, 30% to 108%) higher in patients who died compared with those who survived. The scores for the individual levels of TNF-alpha, IL-1 beta, IL-6, and lipopolysaccharide were summed to arrive at a total lipopolysaccharide-cytokine score, and mortality increased with lipopolysaccharide-cytokine score (P < 0.001). CONCLUSIONS: Patients with the sepsis syndrome have detectable levels of circulating TNF-alpha, IL-1, IL-6, and lipopolysaccharide independent of culture-documented infection. Lipopolysaccharide and cytokines may play a pathogenic role in sepsis, and the combination of several elevated factors may be important in determining patient survival.
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An American College of Chest Physicians/Society of Critical Care Medicine Consensus Conference was held in Northbrook in August 1991 with the goal of agreeing on a set of definitions that could be applied to patients with sepsis and its sequelae. New definitions were offered for some terms, while others were discarded. Broad definitions of sepsis and the systemic inflammatory response syndrome were proposed, along with detailed physiologic parameters by which a patient may be categorized. Definitions for severe sepsis, septic shock, hypotension, and multiple organ dysfunction syndrome were also offered. The use of severity scoring methods when dealing with septic patients was recommended as an adjunctive tool to assess mortality. Appropriate methods and applications for the use and testing of new therapies were recommended. The use of these terms and techniques should assist clinicians and researchers who deal with sepsis and its sequelae.
Central venous catheter placement for access and monitoring purposes is one of the most commonly performed procedures in the intensive care unit. This article details the indications, techniques, and advantages and disadvantages associated with various approaches to central line insertion; complications associated with central venous line insertion are also reviewed briefly.
BACKGROUND AND METHODS: Tumor necrosis factor (TNF) has been implicated as a major humoral mediator of sepsis and endotoxin shock. TNF is secreted by cells of the reticuloendothelial system, including alveolar macrophages. Alveolar macrophage TNF production has been postulated to play a pathogenetic role in the development of adult respiratory distress syndrome (ARDS) in sepsis. To evaluate alveolar macrophage production of TNF during sepsis and endotoxin shock, we studied the effects of sepsis and/or in vivo lipopolysaccharide on the in vitro production of TNF by pulmonary alveolar macrophages. Human pulmonary alveolar macrophages were obtained by bronchoalveolar lavage from six septic and five nonseptic patients, cultured in the presence or absence of lipopolysaccharide (1 ng/mL), and assayed for TNF activity in a bioassay using fibroblast lysis. A murine model of sepsis was also utilized to study pulmonary alveolar macrophage TNF production under more controlled conditions. Normal mice were given ip injections of either lipopolysaccharide or saline. After 2 hrs, pulmonary alveolar macrophages were obtained and cultured in saline or various concentrations of lipopolysaccharide (0.001 to 10 micrograms/mL). RESULTS: There was no difference in baseline TNF activity, expressed as per cent lysis at 1:10 dilution, between pulmonary alveolar macrophages from control and septic patients (35.7 +/- 5.5% vs. 24.4 +/- 9.3%, respectively) (p greater than .05). However, when stimulated with lipopolysaccharide in vitro, the pulmonary alveolar macrophages from nonseptic patients produced significantly (p less than .01) more TNF (82.8 +/- 3.6%) than did pulmonary alveolar macrophages from patients with the septic syndrome (35.2 +/- 3.8%). Similar findings were obtained using the murine sepsis model. The baseline TNF activity in pulmonary alveolar macrophages from control mice was 22.9 +/- 7.0% (mean +/- SEM) and from lipopolysaccharide-injected mice was 26.8 +/- 3.3% (p greater than .05). Stimulation with 1 ng/mL lipopolysaccharide in vitro produced an increase in TNF activity in both groups, but the increase was greater in the control mice (68.1 +/- 5.7%) than in the lipopolysaccharide-injected mice (47.5 +/- 5.3%) (p less than .01). When the murine pulmonary alveolar macrophages were stimulated with higher concentrations of lipopolysaccharide (0.1 to 10 micrograms/mL), pulmonary alveolar macrophages from lipopolysaccharide-injected mice produced less than 25.5% of the TNF produced by pulmonary alveolar macrophages from control mice. CONCLUSIONS: These studies indicate that sepsis and endotoxin injection result in a rapid decrease in the ability of pulmonary alveolar macrophages from both humans and mice to produce and secrete TNF in response to lipopolysaccharide. We speculate that a downregulation of TNF production or of macrophage responsiveness to lipopolysaccharide has occurred. These results suggest that sustained TNF production by macrophages is not required for lung injury in sepsis.
The inability to increase alveolar ventilation can lead to CO2 retention and acute respiratory acidosis in patients with ventilatory limitation. In this case, a young woman receiving maximum ventilatory support was unable to excrete excess CO2, associated with increasing dianeal concentrations of peritoneal dialysis. Since the patient's lung disease had necessitated a large amount of ventilatory support, the patient was unable to increase VE appropriately to handle excess CO2. Peritoneal dialysate was an additional source of carbohydrates. Peritoneal dialysate is an additional carbohydrate source that may result in hypercapnia and respiratory acidosis in patients with respiratory compromise. To our knowledge, this is the first case report in an adult which demonstrates that peritoneal dialysis with high glucose loads produced an acute respiratory acidosis that was reversed by decreasing the glucose concentrations in the dialysate. Excess CO2 production should be considered with respiratory disorders associated with dialysis.
Recent technology in Doppler echocardiography has produced a dual beam Doppler instrument that is capable of insonating the total cross-sectional area of the ascending aorta. The purpose of this study was to evaluate the accuracy of this instrument in measuring cardiac output in critically ill patients by comparing results with those of the thermodilution-derived cardiac output. A technically adequate Doppler cardiac output measurement was attained in 71 (91%) of 78 patients. The range of thermodilution-derived cardiac output measurements was from 1.58 to 11.70 liters/min. To maximize thermodilution cardiac output reliability, several measurements were made for each patient. Those patients in whom the difference between the highest and lowest measurement varied by less than 10% from the averaged results were accepted into the 50 patient study. There was significant correlation between dual beam Doppler- and thermodilution-derived cardiac output (r = 0.96, SEE = 0.55 liters/min, p less than 0.0001). This study demonstrates that dual beam Doppler ultrasound is a promising noninvasive method of measuring cardiac output in the critically ill patient.
Multiple organ system failure is a major cause of mortality in the adult respiratory distress syndrome (ARDS). We serially evaluated parameters of multiple organ function in 24 patients during the first week after the diagnosis of ARDS and related them to outcome. The adult respiratory distress syndrome was associated with sepsis (n = 16), postoperation (n = 7), and trauma (n = 1). Fourteen of the 24 patients (58 percent) died. Although there were no significant differences in the indices of pulmonary or renal dysfunction between survivors and nonsurvivors, evidence of hepatic dysfunction was different in the two groups. On the day we identified ARDS, serum bilirubin was 1.2 mg/dl +/- 0.9 mg/dl in patients who survived, and was 2.3 mg/dl +/- 2.8 mg/dl (chi +/- SD) in those who died. Initial serum glutamic oxalacetic transaminase (SGOT) and alkaline phosphatase levels were lower in survivors than in those who died (71 +/- 44 IU/L vs 399 +/- 807 IU/L, and 121 +/- 53 IU/L vs 269 +/- 243 IU/L, respectively). These abnormalities persisted during the first week of respiratory failure, with significant differences in serum bilirubin and alkaline phosphatase between survivors and nonsurvivors (p less than 0.01). The degree of pulmonary and renal dysfunction was similar in both groups. These data suggest that liver function may be a major determinant of survival in patients with the adult respiratory distress syndrome.
The role of the various cyclo-oxygenase products of arachidonic acid metabolism in the production of the pathologic, physiologic, hemodynamic, and metabolic derangements of sepsis has been reviewed and there is a wide variation in different species and with different models of sepsis. The relationship of these potential mediators cannot be definitely determined. There is much circumstantial evidence that would incriminate the various arachidonic metabolites in the production of the sepsis manifestations; however, we must keep in mind that this may only be "guilt by association." Clearly, the available evidence does suggest that there is some role played by TXA2 and PGI2 in the physiologic and hemodynamic manifestations of sepsis, but the exact role remains undetermined.
The septic syndrome can be defined using clinical criteria in patients with clinical evidence of an infectious process. The other criteria include fever or hypothermia, tachypnea, tachycardia, and evidence of impaired organ perfusion or function as manifested by either altered mentation, hypoxemia, elevated plasma lactate, or oliguria. A multicenter trial using these criteria found positive blood cultures in 45 per cent of 382 patients. The mortality rate was approximately 30 per cent and 25 per cent of the patients developed ARDS. With respect to these characteristics, this septic syndrome population was very similar to the more traditionally defined populations with sepsis. Using the septic syndrome definition may allow for earlier detection of septic patients and possibly allow for earlier therapeutic intervention. The septic syndrome may help identify a population of patients at risk for the various complications of sepsis (that is, ARDS), aid in the search for pathophysiologic mechanisms, and allow for pharmacological trials earlier in the disease process.
The use of mechanical ventilation in septic patients with or without ARDS remains under the category of supportive care. It is the task of clinicians to properly manage the ventilated patient and to prevent complications and treat them as soon as possible, if they arise. All clinicians eagerly await the introduction of agents that will either attenuate the inflammatory response in patients with the septic syndrome prior to the development of ARDS or assist in the healing of the acute injury.
The sepsis syndrome represents a systemic response to infection and is defined as hypothermia (temperature less than 96 degrees F) or hyperthermia (greater than 101 degrees F), tachycardia (greater than 90 beat/min), tachypnea (greater than 20 breath/min), clinical evidence of an infection site and with at least one end-organ demonstrating inadequate perfusion or dysfunction expressed as poor or altered cerebral function, hypoxemia (PaO2 less than 75 torr), elevated plasma lactate, or oliguria (urine output less than 30 ml/h or 0.5 ml/kg body weight.h without corrective therapy). One hundred ninety-one patients with the sepsis syndrome were evaluated prospectively and comprised the placebo group of a multicenter trial of methylprednisolone in sepsis syndrome and septic shock. Forty-five percent of the patients were found to be bacteremic. Thirty-six percent of the patients were in septic shock (sepsis syndrome plus a systolic BP less than 90 mm Hg or a decrease from baseline in systolic BP greater than 40 mm Hg) on study entry. An additional 23% of the patients developed shock after admission with 70% doing so within 24 h of study entry. Shock reversal occurred with a 73% frequency. Twenty-five percent of the patients developed the adult respiratory distress syndrome (ARDS). Mortality for the patients with sepsis syndrome who did not develop shock was 13%. Mortality for the groups of patients with shock on admission and shock postadmission was 27.5% and 43.2%, respectively. Forty-seven percent of the bacteremic patients developed shock after study admission compared to 29.6% of the nonbacteremic patients (p less than .05).(ABSTRACT TRUNCATED AT 250 WORDS)
The role of the polymorphonuclear leukocyte in the development of acute lung injury has been the subject of much controversy. Experimental lung injury is associated with peripheral leukopenia and the intrapulmonary sequestration of leukocytes. We have previously shown that ibuprofen, a nonsteroidal anti-inflammatory drug, can improve the hemodynamic alterations of canine endotoxin shock. Ibuprofen has also been found to decrease leukocyte adherence. We investigated the dose response of ibuprofen on the increased neutrophil adherence and the extent of lung injury associated with canine endotoxin shock. Single doses of ibuprofen (1, 5, 10, and 20 mg/kg iv) were administered 15 min after Escherichia coli endotoxin. Endotoxemia resulted in leukopenia and an increased neutrophil adherence in both aortic and pulmonary artery blood. Endotoxin-treated animals exhibited increased neutrophils in the bronchoalveolar lavage fluid, a marker of lung injury. The 20-mg/kg ibuprofen dose decreased aortic granulocyte adherence at 30 min, while all ibuprofen doses decreased the aortic adherence at 120 min. The increased pulmonary artery neutrophil adherence was not affected by ibuprofen. Histologically, lung injury was manifested by intravascular leukostasis. Ibuprofen treatment did not affect the histologic or morphometric extent of the lung injury. The leukopenia and increased neutrophil adherence occur rapidly after endotoxemia and are associated with subsequent intravascular sequestration of leukocytes. Agents designed to prevent lung injury must either be given before the insult or be able to block the effects of the toxic products released by the activated granulocytes.(ABSTRACT TRUNCATED AT 250 WORDS)
The dose response of the nonsteroidal anti-inflammatory drug, ibuprofen, was evaluated in order to determine the most efficacious dose in the treatment of canine endotoxin shock. Fifteen minutes after an infusion of Escherichia coli endotoxin, four groups of dogs were given a single iv dose of 1, 5, 10, or 20 mg/kg of ibuprofen. These groups were compared to endotoxin only and saline control groups. All ibuprofen doses significantly improved the systolic, diastolic, and mean systemic arterial BP. The improvement in systemic BP was accompanied by an increase in the systemic vascular resistance. Pulmonary vascular pressures and resistance also increased after ibuprofen administration. The lack of a dose response and the demonstrated beneficial effect of low dose ibuprofen in the reversal of the hypotension associated with experimental canine endotoxin shock lead us to recommend the use of low dose ibuprofen for future endotoxin and sepsis studies. Use of low dose ibuprofen might have less of an effect on renal perfusion and would therefore be more likely to produce the beneficial hemodynamic response without compromising renal function.