RESUMEN
AIM: To identify, in vitro, the best fruit juice to use as oral contrast agent in magnetic resonance cholangiopancreatography (MRCP) and to test, in vivo, the best natural juice and the new parameters in MRCP sequences identified in vitro. MATERIALS AND METHODS: The in vitro evaluations consisted of measuring the T2 values of a pure solution of manganese (Mn) and iron (Fe) at different concentrations, measuring the content of Mn and Fe in five commercial juices and their T2 relaxation times, and identifying the optimal juice dilution for suppressing the gastrointestinal fluid signal. The new parameters of MRCP sequences were tested in vivo. RESULTS: Manganese alone strongly influenced the shortening of the T2 values (p=0.004). The T2 value with an echo time (TE) of ≥1,000 ms enabled sufficient intestinal fluid suppression in the case of high juice dilution. A flip angle of 90° maximised the differences between the high signal from static fluids, such as the bile and the fluid in the gastrointestinal tract, using fast imaging employing steady-state acquisition (FIESTA) sequences (p<0.001). CONCLUSION: The shortening of the T2 relaxation time depended only on the Mn concentration. All the commercial juices had an Mn concentration sufficient to suppress the gastrointestinal fluid signal using long TE sequences. The oral ingestion of commercial juice before MRCP was enough to suppress the signal from the gastrointestinal fluids, regardless of its dilution after ingestion. When using FIESTA sequences, a flip angle of 90° allowed the best suppression of gastrointestinal fluid signals.
Asunto(s)
Pancreatocolangiografía por Resonancia Magnética/métodos , Medios de Contraste/administración & dosificación , Jugos de Frutas y Vegetales , Administración Oral , Medios de Contraste/química , Humanos , Técnicas In Vitro , Hierro/química , Manganeso/químicaRESUMEN
This study evaluated performance of individuals exercising at a fixed workload and wearing full-facepiece respirators modified to provide expiratory resistances of 0.27, 0.47, 1.81, 4.43, and 12.27 cmH20 x s x L(-1). On five separate occasions, 15 volunteers exercised to voluntary endpoint on a treadmill at fixed speeds and grades chosen to elicit 85% of maximal aerobic capacity for an unencumbered condition. Exercise performance time was recorded at the cessation of each test. Results showed that performance time decreased linearly (R2 = 0.79; p<0.001) with increased resistances, and no threshold value below which expiratory resistance has no impact on performance was found. Average oxygen consumption rates and minute ventilation also decreased linearly with increased expiratory resistances, indicating that increases in expiratory resistance result in a considerable level of hypoventilation. From the perspective of respirator design, the results of this study suggest that the only practical expiratory resistance level limitation is the reduction in performance that will be acceptable to the end users.
Asunto(s)
Ejercicio Físico/fisiología , Respiración , Dispositivos de Protección Respiratoria , Adolescente , Adulto , Prueba de Esfuerzo , Femenino , Humanos , Masculino , Consumo de OxígenoRESUMEN
Respirators have been found to degrade communication effectiveness when wearers speak face-to-face. However, little is known about communication effectiveness when using the telephone and wearing a respirator. Eleven pairs of subjects were asked to pronounce and identify words chosen from Modified Rhyme Test lists. Each word appeared on a computer screen in one room and the speaker said the word into the telephone. The listener in another room identified the word and typed it into a computer linked with the first. Subjects wore U.S. Army M40 full-facepiece air-purifying respirators with hoods. Three different speech diaphragm arrangements and two hood materials were tested. Results show that accuracy suffered by about 10% when respirators and hoods were worn compared with the control condition. Word identification speed was one-third to one-half of the control (no respirator or hood) condition depending on specific equipment worn.
Asunto(s)
Comunicación , Dispositivos de Protección Respiratoria , Teléfono , Adolescente , Adulto , Análisis de Varianza , Femenino , Humanos , Masculino , Dispositivos de Protección Respiratoria/estadística & datos numéricosRESUMEN
The combined effects of respirator wear and low-intensity work on decision making and mood were assessed in eight subjects during 60 min of low-intensity treadmill walking with and without a respirator to determine whether the stresses of respirator wear negatively impact decision making. Subjects completed walks during no mask wear, wear of a respirator with high inspiratory resistance, and wear of a respirator with low resistance. Cognitive tasks included choice reaction (CHO), serial addition/subtraction (ADD), logical reasoning (LOG), and serial reaction (SER). Mood was measured using a questionnaire with 36 adjectives representing the factors of activity, anger, depression, fear, happiness, and fatigue. Data were obtained preexercise, after 20 and 40 min of walking, and postexercise. Combined respirator wear and low-intensity exercise did not affect accuracy, speed, or throughout in any of the cognitive tasks. Likewise, no significant effects of condition on the six mood factor scores were observed. These results show that the combination of respirator wear and low-level activity does not adversely alter cognitive performance or mood.
Asunto(s)
Afecto/fisiología , Cognición/fisiología , Ejercicio Físico/fisiología , Ejercicio Físico/psicología , Dispositivos de Protección Respiratoria/efectos adversos , Adulto , Toma de Decisiones , Femenino , Humanos , Masculino , Pruebas Neuropsicológicas , Desempeño Psicomotor , Estrés Psicológico/etiología , Estrés Psicológico/fisiopatología , Estrés Psicológico/psicología , Encuestas y CuestionariosRESUMEN
The extent to which sweat accumulation inside respirators affects respirator fit has not been quantified. This study represents an attempt to measure facial sweating and to quantify its effects on fit factors of negative pressure, full-facepiece respirators. Respirator fit factor (FF) data were obtained while 14 subjects completed 30 minutes of treadmill walking at an intensity of 75% of age-predicted maximal heart rate in an aerosol test chamber under ambient environmental conditions. Subject facial and whole body sweat production were also measured. Statistical analysis of the treadmill FF results showed that respirator fit was significantly (p < 0.05) degraded after 14 minutes of exercise. Sweat accumulation inside the respirator facepiece averaged 30.9 +/- 15.5 g. However, no significant correlation of subject facial sweat production with overall FF values measured during exercise was found. The results of this study indicate that respirator FFs degrade significantly over time under moderate exercise and environmental conditions and suggest that facial sweat accumulation alone does not account for the reduced FF levels.
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Cara/fisiología , Respiración Artificial/instrumentación , Sudoración , Adulto , Análisis de Varianza , Diseño de Equipo , Prueba de Esfuerzo , Femenino , Frecuencia Cardíaca/fisiología , Humanos , MasculinoRESUMEN
The purpose of this study was to determine the effects of different inspiratory resistances on exercise performance and to describe physiological and subjective responses during constant load work of an intensity that elicits the maximum sensitivity to respiratory factors of respirator wear. Nine subjects (mean age 25.8 +/- 4.8 years) performed exhaustive treadmill exercise during constant load work of 80% of maximal aerobic capacity while inspiring against one of five randomly assigned inspiratory resistance conditions. For inspiratory resistances of 0.20 kPa (R1), 0.29 kPa (R2), 0.39 kPa (R3), and 0.49 kPa (R4), measured at a steady air flow rate of 85 L min-1, average performance times were 84, 75, 54, and 30% of the control condition. Performance time reductions were significant for R3 and R4 trials. Results also indicated a significantly reduced mean respiration rate, minute ventilation, and oxygen ventilatory equivalent (VE/VO2) for the R4 condition at exercise breakpoint compared to control. For resistances R1-R4, mean VE/VO2 were significantly reduced from control by approximately 12, 17, 19, and 31%. At breakpoint, mean ratings of perceived exertion were similar for control, R1, R2, and R3 conditions but were significantly lower for R4 versus control. Breathing comfort did not differ significantly between resistances below the R3 level, but discomfort was significantly greater for conditions R3 and R4. These findings suggest that the impact of the respiratory limitations of respirators can be diminished by employing respirators with inspiratory resistances below the R3 level.
Asunto(s)
Resistencia de las Vías Respiratorias/fisiología , Tolerancia al Ejercicio/fisiología , Ejercicio Físico/fisiología , Mecánica Respiratoria/fisiología , Adulto , Prueba de Esfuerzo/métodos , Femenino , Humanos , Masculino , Consumo de Oxígeno/fisiología , Soporte de Peso/fisiologíaRESUMEN
Cognitive performance was studied in six male and three female subjects exposed to two randomly administered 10-hour measurement periods, a control condition without a respirator and a respirator wear trial requiring continuous wear, under nonexercise conditions. Reaction time and decision-making speed were assessed using a series of simple and choice reaction time tasks at the start of each test iteration and after hours 2, 4, 6, 8, and 10 of testing. Subject anxiety levels were assessed along with reaction time measures. Visual tracking ability was measured after each hour of testing. Reaction time and decision-making speed did not differ significantly between control and respirator conditions at any time throughout the 10 hours of testing. Female volunteers exhibited significantly faster reaction times and decision-making speeds than males independent of respirator wear conditions and time of measurement. Subject anxiety increased significantly from initial measurements after 8 hours of testing for each condition, but no differences were observed between conditions at any time. Respirator wear did not detrimentally influence visual tracking ability. These findings suggest that respirator wear over a relatively long time period under nonexercise conditions should not significantly inhibit cognitive function.
Asunto(s)
Cognición , Dispositivos de Protección Respiratoria/efectos adversos , Descanso , Adulto , Ansiedad/etiología , Toma de Decisiones , Femenino , Humanos , Masculino , Desempeño Psicomotor , Tiempo de Reacción , Caracteres Sexuales , Factores de TiempoRESUMEN
The Clagett open-window thoracostomy is performed to give patients with empyema improved quality of life and other outcomes. Adult health nurses care for patients undergoing this procedure preoperatively, postoperatively, and at home, and must consider several important issues to prevent serious complications and facilitate family care.
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Empiema/cirugía , Toracostomía/enfermería , Adulto , Empiema/etiología , Humanos , Persona de Mediana Edad , Neumonectomía/efectos adversos , Cuidados Posoperatorios , Cuidados Preoperatorios , Toracostomía/efectos adversos , Toracostomía/instrumentaciónRESUMEN
Reaction time, decision-making speed, and response accuracy were measured in 12 male and 5 female subjects performing computer-controlled tasks under nonexercise conditions during two 3.5-hour days, one with and one without (control) wearing a respirator, to assess the effects of respirator wear alone on cognitive performance. Tasks included measures of simple and choice reaction time (CRT), serial pattern matching, lexical discrimination (LD), visual selective attention, rapid visual scanning, and form discrimination (FD). Anxiety levels were assessed along with reaction time measures obtained at the start of each test day and after 1, 2, and 3 hours of testing. Reaction time and response accuracy did not differ significantly between respirator and control trials and were not changed over time. However, mean decision-making times were significantly faster during respirator wear compared to control for the LD (0.17 +/- 0.04 versus 0.19 +/- 0.05 sec) and FD (0.32 +/- 0.10 versus 0.36 +/- 0.12 sec) CRT tasks. Females exhibited significantly faster reaction times than males, but no differences within sex groups were observed between control and respirator trials. Response accuracy and decision-making speed did not differ within and between male and female groups for any reaction time tasks during respirator wear. The improvements in decision-making time observed during respirator wear probably reflect the effect of the respirator to increase arousal and improve focusing of attention by excluding peripheral visual stimuli. Furthermore, the results suggest that respirator wear over a relatively short period in the absence of other stressors should not inhibit cognitive function.
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Toma de Decisiones , Tiempo de Reacción , Dispositivos de Protección Respiratoria , Análisis y Desempeño de Tareas , Adulto , Cognición , Femenino , Humanos , Masculino , Factores SexualesRESUMEN
Severe lactic acidosis usually accompanies intense endurance exercise. It has been postulated that glycogen depletion working in concert with elevated muscle and plasma lactate levels lead to a concomitant reduction in pH. Their cumulative effect during prolonged physical exertion now leads to muscular fatigue and eventually limit endurance capacity. Therefore in the present study, dichloroacetate (DCA), a compound which enhances the rate of pyruvate oxidation thus reducing lactate formation, has been evaluated in a validated rat model of sub-maximal exercise performance. Male rats (350 g) were divided into two groups (control-saline, i.v. and DCA 5 mg/kg, i.v.) and were exercised to exhaustion in a chamber (26 degrees C) on a treadmill (11 m/min, 6 degrees incline). When compared to controls, the DCA-treated rats had longer run times (169 vs 101 min) and a decreased heating rate (0.020 vs 0.029 degrees C/min). In addition, DCA attenuated the increase in plasma lactate (28 vs 40 mg/dl) and significantly reduced both the rate and absolute amount of depletion of muscle glycogen stores. These results suggest that the activation of pyruvate dehydrogenase activity by DCA resulted in a reduction in the rate of glycogenolysis in addition to decreasing lactate accumulation by presumably limiting the availability of pyruvate for conversion to lactate, therefore increasing muscle carbohydrate oxidation via the TCA cycle. Thus DCA effected a significant delay in muscle fatigue.
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Ácido Dicloroacético/farmacología , Lactatos/sangre , Músculo Esquelético/efectos de los fármacos , Resistencia Física/efectos de los fármacos , Esfuerzo Físico/efectos de los fármacos , Acidosis Láctica/metabolismo , Animales , Regulación de la Temperatura Corporal , Modelos Animales de Enfermedad , Activación Enzimática , Glucógeno/metabolismo , Lactatos/metabolismo , Hígado/efectos de los fármacos , Hígado/metabolismo , Masculino , Fatiga Muscular/efectos de los fármacos , Músculo Esquelético/metabolismo , Oxidación-Reducción , Complejo Piruvato Deshidrogenasa/efectos de los fármacos , Piruvatos/metabolismo , Ratas , Ratas Sprague-Dawley , Carrera , Factores de TiempoRESUMEN
This study was designed to determine the reliability of measurements of respiratory volumes obtained with a respiratory inductive plethysmograph (RIP) during exercise. Tidal volumes (VT) from the RIP were compared with simultaneous flowmeter volumes in 8 healthy subjects at 5 incremental work rates of 60, 90, 120, 150, and 180 W during cycling and treadmill exercise. During cycling, average RIP and flowmeter values did not differ significantly at work rates below 180 W for 63% of the subjects. Average RIP and flowmeter VT were similar at work rates below 180 W for 50% of the subjects, and for 83% of the subjects at intensities below 150 W. The variability in these results may be attributed to several factors including RIP calibration errors and slippage of the RIP elastic bands containing the inductive coils. Correlations of breath-by-breath flowmeter and RIP VT were significant for subjects during cycling (R = 0.73, P < 0.05) and treadmill exercise (R = 0.78, P < 0.05). These findings suggest that the RIP should be considered a semi-quantitative method for measurements of tidal volume during exercise with and without respirator wear.
Asunto(s)
Ejercicio Físico/fisiología , Pletismografía , Volumen de Ventilación Pulmonar , Adulto , Femenino , Humanos , Masculino , Reproducibilidad de los Resultados , ReologíaRESUMEN
Flow probes and nonocclusive catheters were simultaneously implanted in the splanchnic and hindlimb vasculature to measure regional blood flows and arteriovenous differences of individual organs in the conscious rabbit. Pulsed Doppler flow probes were constructed by modifying the technique of Haywood et al., and nonocclusive catheters were designed and constructed from Silastic tubing (0.6- or 0.9-mm OD) and surgical velour. Laparotomy was performed on rabbits under anesthesia, and the renal, mesenteric, iliac, or hepatic artery and portal vein were isolated and instrumented with a flow probe. A nonocclusive catheter was then inserted into the respective vein. Instrumentation of the hepatic system required probes on the hepatic artery and portal vein, and nonocclusive catheters were placed into hepatic and portal veins. One week later, rabbits were reanesthetized and nonocclusive catheters were inserted into the cranial vena cava via the jugular vein and abdominal aorta to the level of the celiac axis. Probes and catheters were evaluated daily up to 30 days. Implants remained functional for an average of 3 weeks, permitting chronic measurement of velocity and blood variables in individual tissue beds of the conscious rabbit.
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Catéteres de Permanencia/veterinaria , Miembro Posterior/irrigación sanguínea , Conejos , Circulación Esplácnica , Animales , Femenino , Arteria Hepática/cirugía , Arterias Mesentéricas/cirugía , Venas Mesentéricas/cirugía , Vena Porta/cirugía , Flujo Sanguíneo Regional , Arteria Renal/cirugía , Venas Renales/cirugíaRESUMEN
Ventilatory patterns and respiratory timing were measured in 14 subjects during cycling (CYC) and treadmill exercise (TM) at similar leg frequencies (fLEG) to determine if mode of exercise affects patterns of ventilation and respiratory timing. Measurements of breathing frequency (fR), tidal volume (VT), expired ventilation (VE), and inspiratory (TI) and expiratory (TE) time were obtained at fLEG of 50, 70, and 90 rev.min-1 (rpm) for CYC and at similar incremental fLEG (strides.min-1; spm) during TM achieved by increasing belt speed at 0% grade. CYC exercise intensity was approximately 50% VO2,max at all fLEG, whereas VO2 increased progressively with TM. fR increased significantly (P < 0.001) with increasing fLEG of TM (20.5 +/- 4.6, 25.4 +/- 5.8, and 36.3 +/- 7.6 breaths.min-1; mean +/- SD), but during CYC fR changed significantly (P < 0.05) only between fLEG of 70 and 90 rpm (25.0 +/- 5.9 vs 28.5 +/- 6.9 breaths.min-1). Both average breath TI and TE obtained by grouping into incremental ranges of fR decreased significantly (P < 0.05) with increasing fR up to 36 breaths.min-1 and the relationships of TI and TE to fR, TI to TE, and central inspiratory drive (VT/TI) to VE were the same for CYC and TM. Group average fR and fLEG were synchronized during TM, but individual subjects did not exhibit a high degree of entrainment. This study shows respiratory timing patterns to be independent of mode of exercise over the range of fR observed when describing patterns by grouping into incremental ranges of fR.
Asunto(s)
Ejercicio Físico/fisiología , Respiración/fisiología , Mecánica Respiratoria , Adulto , Prueba de Esfuerzo , Frecuencia Cardíaca , Humanos , Masculino , Volumen de Ventilación PulmonarRESUMEN
The authors report 57 febrile episodes in 36 patients with leukemia and lymphoma. Patients with less than 1000 granulocytes and fever above 38.5 degrees C were included in this empirical antibacterial protocol (15 mg amikacin/kg/day/iv, 500 mg carbenicillin/kg/day/iv, 200 mg cefoxitin/kg/day/iv). The criteria for diagnosis of infection were those widely accepted [Schimpff et al. 1971]. Microbiologic documentation of infection was performed in 33.4% of febrile episodes. Antibacterial therapy induced an improvement in 75.1% of cases. Clinical response often occurred in the presence of profound granulocytopenia (in 72% of episodes). Therapy failure was higher in pneumonia (46%) and lower in fever of unknown origin (21%).