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Biomedical subjects

C W Lentz

Publications and source records attributed to C W Lentz.

17 recordsLinked to original sources
PubMed1997

Smoke inhalation is a multilevel insult to the pulmonary system.

Inhalation injury represents an ongoing threat to patients with thermal injury. The magnitude of the disease severity is related to the multilevel insult to the pulmonary system. Asphyxiants present in inhaled smoke can compromise oxygen delivery, resulting in cell death. Also, early changes in the microcirculation of the lung parenchyma, related to polymorphonuclear cell activation and oxygen free radical production, are responsible for early pulmonary edema. Perhaps the most significant pathologic change caused by smoke inhalation is loss of the respiratory epithelium and the formation of tracheobronchial casts. The recent application of high-frequency flow interruption ventilation and intrapulmonary percussive ventilation has made the largest impact on improved survival in patients suffering from smoke inhalation.

Animals↗
PubMed1996

Thoracic aorta injuries: management and outcome of 144 patients.

Rupture of the thoracic aorta from blunt injury is often lethal. Methods of operative repair vary, based on the surgeon's preference and circumstances. The primary hypothesis of this study was that operative management choices would correlate with outcome. Data on demographics, injury mechanism, initial evaluation, diagnostic procedures, operative treatment, and outcome were obtained from chart review at the state's eight trauma centers. Rates of paraplegia and survival were compared for different methods of operative repair. Of 63,507 hospitalized trauma patients, 144 patients sustained thoracic aortic injury (incidence = 0.23%). Sixty-four died (44.1%), most of whom died in the emergency department (26) or the operating room (12). Eighty-six patients had complete operative data for analysis, including cross-clamp time and methods of repair. No patient in the group with a cross-clamp time of less than 35 minutes developed paraplegia (p = 0.02). For the patients with longer cross-clamp times, 6 of 14 patients (42.9%) undergoing clamp and sew repair developed paraplegia, as compared to 2 of 37 patients (5.4%) repaired on bypass (p = 0.005). This study suggests that the rate of paraplegia after repair of thoracic aortic injury can be minimized with short cross-clamp times or the use of bypass when long cross-clamp times can be anticipated.

Adolescent↗
PubMed1996

Appropriate use of the Glasgow Coma Scale in intubated patients: a linear regression prediction of the Glasgow verbal score from the Glasgow eye and motor scores.

UNLABELLED: The Glasgow Coma Scale (GCS) has been shown to be a valuable tool in assessing the neurologic and physiologic status of critically ill patients. Unfortunately, the GCS requires assessment of the verbal response of the patient and this can be blocked by intubation. The purpose of this study was to assess the ability of a regression model based upon the eye and motor components of the GCS to accurately predict the verbal response of the GCS. The primary hypothesis was that the verbal response could be derived from the motor and eye responses of the GCS. METHODS: Data were collected prospectively in an intensive care unit computer data base. Patients were divided into training and test data sets. Linear regression was used to derive a model of verbal score from the motor and eye scores of the GCS in the training data set. Correlation between the actual and the predicted verbal scores was calculated. RESULTS: A total of 2,521 GCS assessments were available for analysis. The second order multiple regression model was an accurate predictor of the verbal score (Pearson's Correlation r = 0.9, R2 = 0.8, p = 0.0001) in 1,463 observations in the training data set. Second Order Multiple Regression Model: Estimated GCS Verbal = (2.3976) + [GCS Motor x (-0.9253)] + [GCS Eye x (-0.9214)] + [(GCS Motor)2 x (0.2208)] + [(GCS Eye)2 x (0.2318)] where r = 0.91, R2 = 0.83, and p = 0.0001. The accuracy of this model was confirmed by comparing the predicted verbal score to the actual verbal score in the test data set (n = 736, r = 0.92, R2 = 0.85, p = 0.0001) CONCLUSIONS: The GCS is a useful tool in the intensive care unit and a critical part of the APACHE II assessment of patient acuity. GCS has been shown to be a useful tool in its own right as a predictor of outcome in the critically ill. Its use is limited with intubation. (See Segatore M, Way C: Heart Lung 21:548, 1992; and Lieh-Lai MW, Theodorou AA, Sarnaik AP, et al: J Pediatr 120:195, 1992.) The present study demonstrates that a relatively simple regression model can use the eye and motor components of the GCS to predict the expected verbal component of the GCS, thus allowing the calculation of the GCS sum score in intubated patients.

Adult↗
PubMed1996

Management and outcome of splenic injury: the results of a five-year statewide population-based study.

Although splenectomy was the preferred method of treating the injured spleen in the past, the methods of splenorrhaphy and nonoperative management have appeared to gain in popularity. The purpose of this study was to determine whether the management of splenic injuries has changed over the course of time and if there has been any differences in the morbidity and mortality associated with different methods of treatment. We retrospectively examined the discharge records from 2627 patients with splenic injuries from the North Carolina Discharge Database. There were 2258 adults and 369 pediatric patients for evaluation. The rate of nonoperative therapy increased from 33.9 per cent to 46.3 per cent over the 5 years of the study, whereas the rate of splenectomy decreased from 52.9 per cent to 43.4 per cent over the same time period. Splenorrhaphy was used in approximately 10 per cent of the injuries over the course of the entire study period. Adults treated nonoperatively required late operation 6.0 per cent (49/811) of the time. The pediatric late operation rate for nonoperative management was 0.4 per cent(1/231). Reoperation after splenorrhaphy was 2.9 per cent (7/240) for adult patients and 4.3 per cent (2/47) for pediatric patients. The majority of adults (57.2%) with an Injury Severity Score (ISS) < or = 15 were able to be cared for via nonoperative methods, whereas the majority of adults (66.4%) with an ISS > 15 required splenectomy. The majority of pediatric patients were able to be cared for in a nonoperative fashion in both the ISS < or = 15 (83.4%) and ISS > 15 (45.5%).

Adult↗
PubMed1995

A statewide, population-based time-series analysis of the increasing frequency of nonoperative management of abdominal solid organ injury.

UNLABELLED: Emergency operative intervention has been one of the cornerstones of the care of the injured patient. Over the past several years, nonoperative management has increasing been recommended for the care of selected blunt abdominal solid organ injuries. The purpose of this study was to utilize a large statewide, population-based data set to perform a time-series analysis of the practice of physicians caring for blunt solid organ injury of the abdomen. The study was designed to assess the changing frequency and the outcomes of operative and nonoperative treatments for blunt hepatic and splenic injuries. METHODS: Data were obtained from the state hospital discharge data base, which tracks information on all hospitalized patients from each of the 157 hospitals in the state of North Carolina. All trauma patients who had sustained injury to a solid abdominal organ (kidney, liver, or spleen) were selected for initial analysis. RESULTS: During the 5 years of the study, 210,256 trauma patients were admitted to the state's hospitals (42,051 +/- 7802 per year). The frequency of nonoperative interventions for hepatic and splenic injuries increased over the period studied. The frequency of nonoperative management of hepatic injuries increased from 55% in 1988 to 79% in 1992 in patients with hepatic injuries and from 34% to 46% in patients with splenic injuries. The rate of nonoperative management of hepatic injuries increased from 54% to 64% in nontrauma centers compared with an increase from 56% to 74% in trauma centers (p = 0.01). In patients with splenic injuries, the rate of nonoperative management increased from 35% to 44% in nontrauma centers compared with an increase from 33% to 49% in trauma centers (p < 0.05). The rate of nonoperative management was associated with the organ injury severity, ranging from 90% for minor injuries to 19%-40% for severe injuries. Finally, in an attempt to compare blood use in operatively and nonoperatively treated patients, the total charges for blood were compared in the two groups. When compared, based on organ injury severity, the total blood used, as measured by charges, was lower for nonoperatively treated patients. CONCLUSIONS: This large, statewide, population-based time-series analysis shows that the management of blunt injury of solid abdominal organs has changed over time. The incidence of nonoperative management for both hepatic and splenic injuries has increased. The study indicates that the rates of nonoperative management vary in relation to the severity of the organ injury. The rates increase in nonoperative management were greater in trauma centers than in nontrauma centers. These findings are consistent with the hypothesis that this newer approach to the care of blunt injury of solid abdominal organs is being led by the state's trauma centers.

Humans↗
PubMed1994

Effects of nitric oxide synthesis inhibition in hyperdynamic endotoxemia.

OBJECTIVE: To investigate the effects of N omega-nitro-L-arginine methyl ester, an inhibitor of nitric oxide synthesis, on hemodynamics, gas exchange and oxygen transport in an ovine model of hyperdynamic sepsis. DESIGN: Prospective, nonrandomized, controlled study, with repeated measurements. SETTING: University research laboratory. SUBJECTS: Twenty healthy adult sheep (weighing 20 to 45 kg) were divided into two groups of 12 treated sheep and eight control sheep and studied. INTERVENTIONS: Twenty awake, chronically instrumented sheep received a continuous infusion of endotoxin (10 ng/kg/min) over 48 hrs. Twenty-four hours after the start of the endotoxin infusion, 12 sheep (treatment group) received a bolus of the nitric oxide synthesis inhibitor N omega-nitro-L-arginine methyl ester (25 mg/kg), while the other eight animals (control group) received the carrier (0.9% NaCl). MEASUREMENTS AND MAIN RESULTS: Twenty-four hours after the start of the endotoxin infusion, both groups exhibited a hyperdynamic state with increased cardiac indices, decreased systemic vascular resistance indices, impaired oxygenation, and increased pulmonary shunt fractions. In both groups, oxygen delivery was significantly increased, while oxygen consumption remained virtually unchanged, resulting in a decreased oxygen extraction ratio. In the control group, the significant alterations in systemic hemodynamics, lung function and oxygen transport persisted for the remainder of the study. Administration of N omega-nitro-L-arginine methyl ester normalized cardiac index and systemic vascular resistance index, increased mean arterial blood pressure, and decreased heart rate. Although oxygen delivery significantly decreased after administration of N omega-nitro-L-arginine methyl ester, oxygen consumption did not change, resulting in a normalization of oxygen extraction ratio. Despite a significant reduction of pulmonary shunt fraction, oxygenation did not improve. Pulmonary arterial pressure and pulmonary vascular resistance index showed a peak 2 hrs after administration of the nitric oxide synthesis inhibitor and then tended to decrease. In contrast, the effects of N omega-nitro-L-arginine methyl ester on the systemic circulation persisted for the remainder of the study. CONCLUSIONS: The data support the assumption that augmented nitric oxide production is a major cause of the hemodynamic alterations seen in hyperdynamic endotoxemia. Administration of the nitric oxide synthesis inhibitor N omega-nitro-L-arginine methyl ester normalized the endotoxin-induced hyperdynamic state, but did not impair oxygen consumption, indicating adequate tissue perfusion of metabolically active organs. Inhibition of nitric oxide synthesis may be a therapeutic option in the treatment of hyperdynamic septic patients when conventional therapy fails to maintain a minimum of cardiovascular performance.

Animals↗
PubMed1994

Thromboxane synthetase inhibition and thromboxane receptor blockade preserve pulmonary and circulatory function in a porcine burn sepsis model.

BACKGROUND: Thromboxane A2 (TxA2) is a key mediator in the pathophysiology of severe burns and sepsis. This study was performed to assess the potential benefits of TxA2 synthetase inhibition and TxA2 receptor blockade in sepsis after severe thermal injury. STUDY DESIGN: Pigs with left atrial, aortic, and pulmonary artery catheters received a 40 percent third-degree burn and, 24 hours later, 100 micrograms per kg Escherichia coli endotoxin. The antagonist treatment (BM) group was treated with the TxA2 receptor antagonist BM 13.177, the synthetase treatment (OKY) group with the TxA2 synthetase inhibitor OKY-046, and the control group received saline solution placebo. Another group without burn or endotoxin was used to assess the side effects of BM 13.177. RESULTS: Both drugs significantly attenuated the changes in pulmonary vascular resistance index, cardiac index, arterial PO2, shunt, oxygen delivery, and oxygen consumption seen after endotoxin. However, cardiac index was significantly decreased in group BM before endotoxin. In healthy pigs, BM 13.177 decreased cardiac index and oxygen delivery and increased the pulmonary vascular resistance index. CONCLUSIONS: TxA2 synthetase inhibitors and TxA2 receptor blockers are potentially useful in sepsis after severe burns. Comparison between drugs was complicated by the adverse effects of the antagonist, and further investigation with other antagonists is needed.

Animals↗
PubMed1993

Heparin in experimental hyperdynamic sepsis.

OBJECTIVE: To evaluate the hypothesis that heparin administration increases cardiac output and improves oxygenation in experimental hyperdynamic sepsis in sheep. DESIGN: Prospective trial. SETTING: Laboratory at a large university-affiliated medical center. SUBJECTS: A total of 14 sheep weighing 28 to 44 kg. INTERVENTIONS: All 14 chronically instrumented sheep received a continuous infusion of Escherichia coli endotoxin (10 ng/kg/min) over 24 hrs. Seven sheep received a fixed bolus of beef lung heparin (5000 units) every 4 hrs intravenously. The other seven sheep served as controls. MEASUREMENTS AND MAIN RESULTS: The heparinized animals showed a triphasic cardiovascular response. Cardiac index increased (p < .05), and systemic vascular resistance index decreased (p < .05) at 2 hrs after the start of the endotoxin infusion (early phase, 0 to 2 hrs). Both variables returned to approximately baseline levels at 4 hrs (second period, 2 to 4 hrs). A hyperdynamic state (in terms of an increased cardiac index), a decreased systemic vascular resistance index, and a decreased mean arterial pressure (MAP) (p < .05 for all) was observed in the third phase (8 to 24 hrs). In the control group, cardiac index, systemic vascular resistance index, and MAP showed no changes in the first period, but a slight decrease in cardiac index and a slight increase in systemic vascular resistance index in the second period. The onset of the hyperdynamic state was less pronounced in the control group and cardiac index was lower (p < .05); likewise, systemic vascular resistance index was increased (p < .05) when compared with heparinized animals. Both groups developed pulmonary hypertension during the endotoxin infusion. The gas exchange in the heparin group was significantly impaired in the first and second periods, but returned to baseline levels in the hyperdynamic phase, whereas the oxygenation of the nonheparinized animals showed only minor changes in the first and second phases, but deteriorated significantly during the third phase of endotoxemia. CONCLUSIONS: In this experimental model of hyperdynamic sepsis, heparin significantly influenced the cardiopulmonary performance. Heparin preserved gas exchange and increased cardiac output but lowered systemic vascular resistance and MAP in the hyperdynamic state.

Animals↗
PubMed1993

Effects of halothane anesthesia on vasoconstrictor response to NG-nitro-L-arginine methyl ester, an inhibitor of nitric oxide synthesis, in sheep.

This study tests the hypothesis that halothane-induced inhibition of the endothelium-derived relaxing factor/nitric oxide (EDRF/NO) pathway significantly contributes to cardiovascular performance and thus reduces the vasoconstrictor response to NO synthesis inhibitors in vivo. We determined the effects of the administration of the NO synthesis inhibitor NG-nitro-L-arginine methyl ester (L-NAME) in chronically instrumented, halothane-anesthetized sheep and in awake control animals. Six sheep underwent halothane anesthesia (1.5 vol%) with mechanical ventilation. Five sheep were studied in the awake state with spontaneous breathing. Both groups received a bolus of L-NAME (25 mg/kg), followed 4 h later by L-arginine (300 mg/kg) to reverse the effects of L-NAME. L-NAME administration caused a significant increase in pulmonary and systemic vascular resistance (P < 0.05) in both groups. However, L-NAME produced a sharp increase in mean arterial and pulmonary artery pressures only in the control group, whereas the pressor response in the halothane group was attenuated. Cardiac output, which was significantly lower after L-NAME administration in both groups, increased after L-arginine. The results suggest that halothane does not significantly alter the EDRF/NO-mediated effects on the vasculature but potentiates the cardiac depressant effect of L-NAME.

Anesthesia, Inhalation↗
PubMed1992

Reversal of hyperdynamic response to continuous endotoxin administration by inhibition of NO synthesis.

Septic shock is characterized by an increase in cardiac output and a fall in systemic vascular resistance index and mean arterial pressure. Endotoxin alters the smooth muscle function of blood vessels, probably by means of an increased production of the potent vasodilator nitric oxide (NO). The present study was accomplished to determine how the inhibition of NO synthesis influences cardiovascular performance in an ovine model of hyperdynamic endotoxemia. Endotoxemia was induced in five range ewes (41 +/- 2 kg) by continuous infusion of Escherichia coli endotoxin (LPS, 10 ng.kg-1.min-1) over the entire study period. After 24 h of LPS infusion, cardiac output increased from 5.2 +/- 0.3 to 7.9 +/- 0.6 (SE) 1/min (P less than 0.05) and mean arterial pressure and systemic vascular resistance index fell from 92 +/- 5 to 79 +/- 6 mmHg (P = 0.08) and from 1,473 +/- 173 to 824 +/- 108 dyn.s.cm-5.m2 (P less than 0.05), respectively. The pulmonary shunt fraction increased from 0.23 +/- 0.03 to 0.32 +/- 0.03 (P less than 0.05). The intravenous administration of the NO synthase inhibitor N omega-nitro-L-arginine methyl ester (25 mg/kg) 24 h after the start of the LPS infusion changed these values to approximately baseline levels over the subsequent 4 h. Although N omega-nitro-L-arginine methyl ester increased pulmonary arterial pressure and pulmonary vascular resistance (P less than 0.05), right and left ventricular stroke volume index showed no significant changes. It is concluded that NO has a major function in cardiovascular performance in endotoxemia.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Lymph and blood flow responses in central airways.

The lymphatic drainage of the lung has been used as a quantitation of pulmonary microvascular fluid flux in normal animals and after various forms of injury. This review supports the importance of the bronchial microvasculature in the formation of lung lymph. Proof that the lymph drainage of the lung comes from the pulmonary circuit has been based on the finding of an elevation of lymph flow when the pulmonary venous pressure is elevated. This proof is wanting since recent work demonstrates that the venous drainage of the intrapulmonary bronchi flows into the pulmonary vascular system at the precapillary level. The administration of endotoxin induces an elevation of lung lymph. The bronchial circuit may play a role in this response since it is likewise exposed to the high pulmonary pressures induced by endotoxin, and there is evidence that ischemia/reperfusion injury to the airway occurs with endotoxin administration. After acute lung injury from smoke inhalation, lung lymph flow is markedly elevated. The lymph drainage from the airway may play an important role in this response. Bronchial blood flow is markedly increased after inhalation injury and there is airway edema. The increases in lung lymph flow and extravascular lung water are markedly reduced by occlusion of the bronchial artery. These data support the need for additional study of the role of the bronchial circulation in the formation of lung lymph.

Animals↗
PubMedDate not supplied

The epidemiology of methicillin-resistant Staphylococcus aureus in a burn center.

The emergence of methicillin-resistant Staphylococcus aureus (MRSA) in a critical care facility creates a multifaceted epidemiological problem in uncovering the source of infection. This study was undertaken to determine the true etiology of MRSA burn wound infections. Patients with a 30% or greater TBSA burn had both burned and unburned skin surface cultured upon admission, using RODAC plates. All other body fluids were cultured when sepsis was suspected. Admission cultures of 14 patients who developed MRSA wound infections were examined for methicillin-resistant organisms. Both admission isolates and infection isolates were compared by antibiogram analysis. Of the 14 patients admitted who developed MRSA infections, 57.1% of these had methicillin-resistant staphylococci present on admission. However, the remaining 42.9% of the patients had methicillin-sensitive, B-lactamase positive staphylococci present on admission. Isolates of group D streptococci resistant to methicillin were isolated in 35.7% of the patients. This data suggests that burn wound infections caused by MRSA very likely arise from the endogenous flora present at the time of injury through conferring the resistant plasmid by conjugational transfer.

Burn Units↗
PubMedDate not supplied

A biopsy of the use of the Baxter formula to resuscitate burns or do we do it like Charlie did it?

The Baxter formula is commonly used to calculate fluid requirements. Baxter reported that 12% of patients would require more than 4.3 mL/kg per percentage of total body surface area (%TBSA). We anecdotally observed that we frequently exceeded the predictions of the formula, and we wondered if this was unique to our practice. We studied our last 11 burn-related resuscitations and collected fluid resuscitation data from US burn centers. Twenty-eight centers were queried, and 6 centers shared data. We were therefore able to study the resuscitation data of 50 adult patients. For 29 patients (58%), 4.3 mL/kg/%TBSA was exceeded compared with the 12% reported by Baxter. These findings suggest that in actual practice, fluid volumes administered are larger than the Baxter formula predicts. This survey does not explain why. Possible reasons for the larger fluid volumes are as follows: (1) the sample is not representative; (2) the formula is used improperly; (3) burns have changed and require more fluids; (4) burn care has changed.

Adult↗