Blood cholesterol screening influence of fasting state on cholesterol results and management decisions.

OBJECTIVE: To compare fasting and nonfasting total and high-density lipoprotein (HDL) cholesterol values in adults and to determine how closely classification into risk groups for coronary heart disease based on nonfasting blood tests compares with classification based on fasting studies. DESIGN: Cross-sectional study. SETTING: A community hospital general internal medicine clinic. PATIENTS: One hundred eighty-one patients at least 20 years of age receiving medical care at a community hospital general internal medicine clinic. INTERVENTIONS: Total and HDL cholesterol levels were measured twice in each patient within 7 days, once while not fasting and once after a minimum 12-hour fast. MEASUREMENTS AND MAIN RESULTS: Fasting and nonfasting total and HDL cholesterol values were compared, patients were classified into desirable, borderline-high, and high cholesterol groups on the basis of fasting and nonfasting blood studies. There were small, statistically significant but clinically insignificant differences in fasting and nonfasting results for total cholesterol. Nonfasting HDL cholesterol levels were similar to fasting HDL levels. The agreement in classification of patients into desirable and high-cholesterol groups between fasting and non-fasting blood testing was 86.7% and 89.5%, respectively. In the borderline-high group, for whom levels of HDL cholesterol are important in determining subsequent management, there was 95% agreement between fasting and nonfasting HDL cholesterol results. Only a small fraction of the patients were classified into lower-risk groups by the nonfasting assessment, creating the potential for less-rigorous monitoring and treatment of their cholesterol status than if fasting results were utilized. These findings were confirmed in this study also for the subgroups of men aged 35 years and older and women aged 45 years and older. CONCLUSIONS: Screening nonfasting adults for total and HDL cholesterol is appropriate for making decisions about primary prevention of coronary heart disease.

Missed injuries in pediatric trauma.

Missed injuries in trauma continue to be a nemesis to the trauma surgeon. Missed injuries in adult trauma patients range in frequency from 9 to 28 per cent, with some being life threatening or permanently disabling. We report the incidence of missed injuries in pediatric trauma to be 20 per cent, in our retrospective review of 107 severe pediatric trauma patients. These missed injuries, however, were neither life threatening nor permanently disabling. We also found that mechanism of injury and patient age affected the incidence of missed injuries in our population.

Bystander Trauma Care training in Iowa.

OBJECTIVE: The Iowa Bystander Trauma Care program trained citizens to provide initial care at the scene of a motor vehicle crash. The development, implementation, and evaluation of the program are described. METHODS: The National Highway Traffic Safety Administration's curriculum was used as the basis for developing the Iowa Bystander Trauma Care program. Emergency medical technicians (EMTs) were trained to be instructors in a two-hour course offered at each of four community colleges. The EMTs, in turn, provided instructions to the general populace. Five hundred participants were given a questionnaire before the one-hour Bystander Trauma Care training session, immediately after the training and six months later. The questionnaire obtained background data and assessed attitudes regarding willingness to stop and assist, and knowledge obtained. RESULTS: One hundred twenty EMT instructors trained more than 2,000 citizen bystanders in a 17-county area in central Iowa. Immediately after the training program, participants were more likely to provide assistance (p < 0.001), and understand the sequence of actions to be performed at the scene of a crash and how to prioritize the information provided to 911 (p < 0.05). There was also evidence of retention of the knowledge six months after training. CONCLUSIONS: Citizens readily volunteered for the Bystander Trauma Care training program. Results of the questionnaire suggest citizens can be successfully trained to recognize the needs of, and provide initial care for, acutely injured persons, and the positive effects of such training are maintained over time.

Continuous dose furosemide as a therapeutic approach to acute respiratory distress syndrome (ARDS).

BACKGROUND: Acute respiratory distress syndrome (ARDS) is seen in a variety of clinical settings in critically ill patients. ARDS has been defined as a clinical syndrome characterized by progressive hypoxemia, tachypnea, and generalized patchy bilateral pulmonary infiltrates in the absence of cardiac failure. Furosemide has been shown to improve pulmonary gas exchange and intrapulmonary shunt in animal models of ARDS by preferential perfusion of nonedematous lung units. We hypothesized that continuous dose furosemide would improve lung injury during resuscitation from oleic acid-induced lung injury in canines. METHODS: Ten mongrel dogs were anesthetized and given intravenous oleic acid (0.1 mg/kg) to induce lung injury. Once lung injury was established (2 h) the control animals (n = 6) were continued on standard supportive therapy, and the study animals (n = 4) were started on continuous dose furosemide at 0.2 mg/kg/h. Cardiac filling pressures were maintained in all animals by infusion of isotonic saline solution. Data collected included lung injury score (LIS), cardiac index (CI), stroke volume index (SVI), pulmonary capillary wedge pressure (PCWP), urine output (UO), volume of resuscitation (VR), and pulmonary shunt fraction (Qs/Qt). Data were collected at baseline, established lung injury (2 h), and end of protocol (6 h). Data were compared between groups at various stages of the model using one-way analysis of variance with repeated measures. RESULTS: All 10 animals survived the protocol. There was no difference between the experimental and control groups at baseline or established lung injury (2 h) for CI, SVI, PCWP, or VR. There was a significant improvement in PO2/FIO2 and reduction of PEEP values in the furosemide group. There was also a statistically significant difference between experimental and control groups in LIS, Qs/Qt, and urine volumes. CONCLUSIONS: Continuous dose furosemide therapy improves LIS, PO2/FIO2, and Qs/Qt and decreases PEEP requirements in this oleic acid model of ARDS.

The efficacy of laparoscopic examination of the internal inguinal ring in children.

The ability of physicians to identify a patent processus vaginalis by laparoscopic examination of the internal ring is now well established, but the efficacy on patient outcome is not. The authors reviewed their experience to determine the effect of diagnostic laparoscopy of the internal ring on the management of children with inguinal hernias. The records of 150 children who underwent inguinal surgery were reviewed--75 before (group 1) and 75 after (group 2) pediatric laparoscopy was introduced into the authors' practice. The children in group 1 were selected for unilateral or bilateral surgery based on history, age, sex, side of presentation, and parental preference. For group 2, laparoscopy was an additional option offered to appropriate patients. Laparoscopy was performed in 43 group 2 patients, using an infraumbilical site. The minimum follow-up period was 2 years for group 1 and 1 year for group 2. The mean ages for groups 1 and 2 were 41.2 and 39.7 months, respectively. There were 61 boys and 14 girls in each group. The percentages of right (R), left (L), and bilateral (B) findings, based on clinical observation, were 56.0 (R), 29.3 (L), and 14.7 (B) for group 1, and 58.7 (R), 26.6 (L), and 14.7 (B) for group 2. The incidence of bilateral surgical exploration was similar for the two groups (group 1, 58.6%; group 2, 61.3%). The addition of laparoscopy significantly lowered the incidence of negative explorations (group 1, 16.0%; group 2, 2.6%; P < .01).(ABSTRACT TRUNCATED AT 250 WORDS)

Does the duration of N2O administration affect postoperative nausea and vomiting?

Nausea and vomiting are the most frequent postoperative complications in the ambulatory surgical setting. In the present study, data were obtained from 184 adult ambulatory cosmetic surgery patients to determine if the use of nitrous oxide (N2O) was associated with an increased incidence of postoperative nausea and/or vomiting (PNV). Anesthesia was induced with thiopental and maintained with an opioid (fentanyl or sufentanil) and isoflurane with or without N2O. Data were analyzed statistically using the two-way chi-square test and the Fisher Exact Test. The major finding was that the incidence of PNV was directly related to the duration of anesthesia in the patients who received N2O, but not in those who were N2O-free. Anesthesia times and the percentages of patients who exhibited PNV in the N2O-free and N2O-treated groups, respectively, were: (1) less than 1 hour, 0% and 6.3%; (2) between 1.0 and 1.9 hours, 35.3% and 36.8%; (3) between 2.0 and 2.9 hours, 24.2% and 66.7% (p = .06); (4) between 3.0 and 5.3 hours, 35% and 100% (P less than .05). Thus, avoidance of N2O in ambulatory cosmetic surgery cases lasting 3, and quite probably 2 or more hours in which general anesthesia is maintained with a synthetic opioid and isoflurane appears to reduce the likelihood that these short-stay patients will experience PNV.

Blood pressure and neurogenic adaptations to reduced dietary sodium in the SHR model of hypertension.

Sodium (Na) balance is maintained by a complex set of genetic, hemodynamic, hormonal and neural mechanisms that affect intake, reabsorption and excretion. This research focused on the role of a reduction in dietary Na on cardiovascular and neuroeffector function in normotensive (WKY) and spontaneously hypertensive rats (SHR) raised from 5-20 weeks on a control Na diet (12 mmol per 100 g food) or various low Na diets (0.5-2 mmol per 100 g food). For comparison purposes, high Na (140 mmol per 100 g food) results are reported. With regards to hemodynamics and volume regulation, the lowest Na diet reduced blood pressure 15% in SHRs but not in WKYs. Body weights, blood volume, hematocrit, plasma electrolytes, extracellular volume, and cardiac output were not different between diets or strains. However, both SHR and WKY low Na groups were abnormally sensitive to blood loss and showed attenuated pressor responses, mediated by the sympathetic nervous system, to both acute and chronic stress situations. Low Na treatment significantly attenuated the pressor response during stress, which was primarily due to reduction in noradrenergic transmitter release. In spite of depressed function during restriction of dietary Na, compensatory responses were adequate to maintain homeostasis, but the neurohumoral compensatory reserve was thereby markedly curtailed. The data suggest that risks are associated with a reduced intake of dietary Na. These findings imply that the "hygienic" Na intake in man should be carefully experimentally defined before generalized measures are taken to reduce dietary Na in society.

Why the phantom p-wave during general anesthesia?

Although atrioventricular junctional rhythm (AVJR) is frequently encountered during general anesthesia, its genesis is poorly understood. The present study was undertaken to test the hypothesis that AVJR is promoted by hypocarbia. One hundred patients (69 females, 31 males), ASA Physical Status Class I, who were 20 to 30 years old, were studied. One-half of the patients were induced with thiopental and maintained with 0.5 to 2.1% isoflurane, 70% nitrous oxide (N2O) and oxygen. The other half of the patient population was induced with thiopental and fentanyl or alfentanil and maintained with the opioid, 70% N2O and oxygen. During maintenance, each patient was hyperventilated to an endtidal carbon dioxide level of 20 to 25 mm Hg and the electrocardiogram recorded to determine if the p-wave disappeared, which is the obvious manifestation of AVJR. During normocarbia, none of the 100 patients developed AVJR. During hypocarbia, the incidences of AVJR during isoflurane-N2O anesthesia and opioid-N2O anesthesia of 18% and 26%, respectively, were significant by chi-square analysis. Consequently, the data suggest that hypocarbia may promote AVJR during general anesthesia.

Risks associated with dietary sodium reduction in the spontaneous hypertensive rat model of hypertension.

Sodium balance is maintained by a complex set up of hemodynamic, hormonal and neural mechanisms that affect intake, reabsorption and excretion. The focus of the following research was on the cardiovascular and neuroeffector effects of dietary Na reduction primarily in normotensive Wistar-Kyoto (WKY) and spontaneously hypertensive rats (SHR) raised from 4 to 15 weeks on a control Na diet (CNa: 12 mmol per 100 g food) or various low Na diets (LNa: 0.5 to 3 mmol per 100 g food). With regards to hemodynamics and volume regulation, the lowest Na diet reduced blood pressure 15% and raised resting heart rate (20%) in SHRs but not WKYs. Blood volume, hematocrit, plasma electrolytes, extracellular volume, and cardiac output were not different between diets or strains. However, both LNa strains were abnormally sensitive to blood loss and showed attenuated pressor responses to both acute and chronic stress situations. Cardiac function was not altered by LNa treatment in either rat strain although structural compensations occurred. LNa treatment significantly attenuated the pressor reduction in mesenteric blood flow during stress which was primarily due to reduction in noradrenergic transmitter release and not due to altered receptor sensitivity, density, or Na/K ATPase activity. Compensatory sympathetic activity was increased as was sodium conservation through humoral mechanisms which maintained homeostasis. However, further neurohumoral compensation was markedly reduced. The data suggests that the hygienic sodium intake in humans should be experimentally defined before generalized measures are taken to reduced dietary sodium use throughout society.

Left ventricular mass and fluid compartmentalization in Wistar-Kyoto and spontaneously hypertensive rats fed high- or low-sodium diet.

Our purpose was to test the hypothesis that a high sodium intake promotes fluid volume expansion, and hence weight gain, in the left ventricle. Between 6 and 30 weeks of age, Wistar-Kyoto (WKY) and spontaneously hypertensive rats (SHR) were fed low-, control- or high-sodium chow. After treatment, known quantities of 22NaCl and Na2(35)SO4 were injected intravenously into each animal and permitted to equilibrate with body fluids in order to measure sodium and sulphate spaces in various tissues. Fluid spaces in left ventricle, as well as in right ventricle, skeletal muscle, kidney and whole-body, of high-sodium groups were similar to those of control- or low-sodium groups. We conclude that high intake of dietary sodium is a factor that promotes myocardial hypertrophy, and the mechanism appears to be independent of arterial blood pressure and intravascular volume.

Left ventricular function of the isolated, genetically obese rat's heart.

We sought to determine if left ventricular (LV) function of the heart from the adult, chronically obese animal is impaired. Hearts from 50 wk-old genetically obese female Zucker rats (624 +/- 13 g) and their lean littermate controls (275 +/- 5 g) were isolated during ether anesthesia, supported metabolically by retrograde aortic perfusion (6 ml/min, 35 degrees C) with physiological solution containing suspended canine erythrocytes (hematocrit, 20%), and the ventricles were paced at 180 beats/min. A distensible, fluid-filled balloon was placed in the LV, and pressure-volume (PV) relationships were obtained. The obese and lean end-diastolic PV curves were not different, and therefore the obese and lean LV chamber compliances were similar. Comparison of the systolic PV relationships demonstrated that the obese rat's heart had a greater pressure-generating capability, which probably was a reflection of its increased LV mass (0.96 +/- 0.03 vs. 0.72 +/- 0.02 g). The calculated average meridional (or circumferential) peak systolic wall stress in the LV of the obese rat's heart, however, was significantly reduced compared with control. This diminished ability to develop systolic stress from the same end-diastolic volumes suggests that the hypertrophied LV of the middle-aged obese rat's heart is dilated or that its contractility is depressed, or both.

O2 reserve of left ventricle of isolated, saline-perfused rabbit heart.

The heart from the pentobarbital-anesthetized rabbit was isolated, and a fluid-filled balloon was placed in the left ventricular chamber for assessment of isovolumic pressure development. The bicarbonate-buffered, physiological perfusate was aerated initially with 95% O2-5% CO2, and then progressive decreases in arterial O2 content (CaO2) were produced in a stepwise fashion by substituting N2 for O2 in the aerating gas mixture. If, for a specified set of experimental conditions, no change in ventricular function occurred after the initial decrease in CaO2, it was concluded that the heart was oxygenated adequately prior to the first CaO2 decrement. Accordingly, with perfusate flow constant at 35 ml/min, adequate oxygenation was achieved during aeration of perfusate with 95% O2 when ventricular contraction rate was 30 beats/min and temperature (T) 22 degrees C. The preparation may have been just marginally O2 sufficient when rate was 60 beats/min (T, 25 or 30 degrees C), but probably was hypoxic when contraction rate was 120 beats/min (T, 30 or 37 degrees C). Perfusion with pressure kept constant at 80 mmHg did not appear to alleviate this hypoxia when metabolism was elevated (rate, 120 beats/min; T, 37 degrees C). Thus, unless the contraction rate is very low, the addition of an O2-carrying vehicle to the perfusate appears to be necessary if O2 delivery to the isolated rabbit heart preparation is to be supramaximal.

Ouabain-induced mechanical toxicity: aberrations in left ventricular function, calcium concentration, and ultrastructure.

The isolated rabbit heart was employed to determine if the myocardial mechanical dysfunction (mechanical toxicity) produced by digitalis was accompanied by ultrastructural lesions and an excessive accumulation of calcium by the cardiac cell. Ouabain (1.2 or 2.4 microM) produced a transient increase and then a continuous decrease in the systolic pressure development by the isovolumic left ventricle. The end-diastolic pressure increased progressively during the time that the systolic pressure was diminishing. The ultrastructural abnormalities that were observed in the ouabain-treated hearts included swollen mitochondria, hypercontracted sarcomeres and, occasionally, myofibrillar disruption. The left ventricular cellular calcium concentration was increased (P less than 0.05) in these mechanically toxic hearts and this increase correlated significantly (r = 0.65, P less than 0.05) with the magnitude of the increase in end-diastolic pressure. Furthermore, a reduction in the perfusate calcium concentration did not attenuate the ouabain-stimulated uptake of calcium. The data suggest that the impaired mechanical performance and the ultrastructural aberrations that may develop in the digitalis-treated heart are related to an excessive uptake of calcium by the left ventricle.

Criteria for adequate oxygenation of isometric kitten papillary muscle.

Papillary muscles were taken from the right ventricles of hearts excised from chloroform-anesthetized kittens. Progressive 100-mmHg stepwise decreases in superfusate oxygen partial pressure (PO2) from control (95% O2 aeration, PO2, 620-650 mmHg) were produced, and subsequent changes in isometric active and resting tension were measured. If, under a given set of experimental conditions, the initial decrement in PO2 produced no decrease in active tensions development, it was concluded that complete oxygenation of the entire muscle cross section was achieved when bath PO2 was maximal. Accordingly, adequate muscle oxygenation during 95% O2 aeration occurred when temperature, stimulation rate, and mean muscle diameter were, respectively, 1) 37 degrees C, 30 beats/min, and 0.89 +/- 0.06 mm; 2) 30 degrees C, 30 beats/min, and 0.94 +/- 0.02 mm; and 3) 30 degrees C, 12 beats/min, and 1.15 +/- 0.09 mm. On the other hand, adequate oxygenation at either 30 or 37 degrees C was not demonstrable when rate was 60 beats/min and muscle diameter exceeded 0.60 mm. We conclude that very low stimulation rates are required for oxygen sufficiency unless the papillary muscle is extremely thin.

Magnesium net fluxes and distribution in rabbit myocardium in irreversible contracture.

Distribution of magnesium (Mg) in heart muscle was studied by measuring fluxes of Mg and transmembrane potentials as a function of perfusate [Mg2+] after a massive increase in permeability of the sarcolemma was induced in the Langendorff prepared heart from the Nembutal-anesthetized rabbit. After onset of 0 mM [Ca2+] perfusion which produced excitation-contraction (E-C) uncoupling and mechanical arrest, action potentials recorded from subepicardial cells showed an increase in duration and decrease in amplitude, which progressed until no transmembrane potentials could be observed. Restoration of physiological salt solution perfusion after 15 min of [Ca2+]-free perfusion caused an irreversible contracture that was associated with 1) efflux of potassium (K) and myoglobin, 2) perfusate [Mg2+]-dependent flux of Mg, and 3) transmembrane potentials of 0 mV. The magnitude of net efflux of K and myoglobin during contracture was unaffected by perfusate [Mg2+]. During the first 2 min of contracture, net efflux of Mg (mumoles per gram wet muscle +/- SE) was 1.37 +/- 0.09 and 0.48 +/- 0.19 during 0 mM and 2.5 mM [Mg2+] perfusion, respectively; but a net influx of 0.56 +/- 0.23 occurred during 5 mM [Mg2+] perfusion. Total sarcoplasmic [Mg] may correspond to perfusate [Mg2+] of 3.6 mM, which was found by interpolation to prevent any net flux of Mg during contracture. 3.6 mM may, therefore, represent the upper limit of the intracellular free-ionized Mg concentration in rabbit heart.

Effect of nitroglycerin with and without systemic hypotension on canine regional myocardial tritiated water deposition.

A marked alteration in the transmural distribution of left ventricular blood flow, with a relative increase in subendocardial and mid-wall flows, but with no change in the distribution of the relative blood flow to the two ventricles occurred when nitroglycerin was administered and the systemic arterial blood pressure in the upper body maintained near control levels in anaesthetized, open-chested dogs. The relative increase in subendocardial and mid-wall flows may have resulted from a direct action of nitroglycerin on the coronary vasculature. On the other hand, the intravenous administration of nitroglycerin, when followed by the hypotension which it produces, did not alter the transmural distribution of blood flow in the left ventricle of the dog. Blood flow to the right ventricle relative to flow to the left ventricle increased in this situation.