摘要:

ObjectiveTo evaluate and refine indirect calorimetry measurement techniques so that accurate metabolic measurements can be performed in mechanically ventilated and convalescing preterm infants who require supplemental oxygen.DesignLaboratory validation of an indirect calorimeter; clinical and laboratory assessments of technical problems in performing metabolic measurements; and clinical indirect calorimetry studies in mechanically ventilated and nonventilated preterm infants.SettingNeonatal intensive care unit (ICU) in a tertiary care university hospital.PatientsLevel II and level III mechanically ventilated (n = 10) and nonventilated (n = 14) neonatal ICU patients who required FIO2levels ranging from 0.21 to 0.42.InterventionsNone.Measurements and Main ResultsSystem calibration was assessed by combustion of 100% ethanol; the mean respiratory quotient was 0.667 +/- 0.001 (SEM). In addition, oxygen consumption (VO2) and CO2production (VCO2) were simulated by CO2/nitrogen infusions within the range expected for 0.5- to 7-kg infants. Mean relative errors were 0.6 +/- 0.3% and 1.8 +/- 0.3% for expected VO2and VCO2values, respectively. In 27 mechanically ventilated patients with no audible endotracheal tube leak, measured endotracheal tube leak ranged from 0.0% to 7.5%. Fluctuations in FIO2during mechanical ventilation were monitored in 30-min studies, using wall-source (n = 27) or tank-source (n = 11) supplemental oxygen. Mean FIO2variation was 0.00075 +/- 0.00013 vs. 0.00011 +/- 0.00001 using wall-source and tank-source oxygen, respectively. Some of the difficulties of obtaining accurate measurements in supplemental hood oxygen studies were overcome by using tank-source vs. wall-source oxygen and a unique hood design.ConclusionsAccurate indirect calorimetry studies can be performed in both ventilated and nonventilated infants weighing as little as 500 g, providing that sufficient attention is paid to technical and methodologic measurement details. (Crit Care Med 1997; 25:171-180)

ISSN:0090-3493    

出版商:OVID    

年代:1997

数据来源: OVID

摘要:

ObjectiveTo determine the role of catechol-O-methyltransferase (COMT) in the biodisposition of pharmacologic concentrations of dopamine.DesignThe study was an open-label dose escalation trial in which dopamine was employed as the sole exogenous catecholamine. The dosage was adjusted to achieve improvements in cardiac output or to augment renal function.SettingA 16-bed pediatric intensive care unit serving both medical and surgical patients.PatientsThe study was performed using 14 dopamine-treated and five untreated control patients. Children ranged in age from 16 days to 12 yrs; five of the treated patients and two of the untreated controls were female. All but one of the study patients were enrolled within 24 hrs of palliative or corrective surgery for congenital heart disease. Control patients had noncardiac surgical procedures. Both treated and control groups were similar with respect to severity of illness, as judged by Therapeutic Intervention Scoring System score.InterventionsAll treated patients received dopamine as a continuous intravenous infusion. Infusion rates were determined by caregivers and ranged from 3.0 to 20 micro g/kg/min.Measurements and Main Results100 ng/mL.ConclusionsThese data demonstrate marked age and concentration-dependent differences in dopamine clearance that account for large interindividual differences in the steady-state plasma dopamine concentrations in patients receiving similar infusion rates. While concomitant variability in COMT activity is observed, the lack of correlation between dopamine clearance and COMT activity suggests that COMT is not rate-limiting for the clearance of exogenously administered dopamine. (Crit Care Med 1997; 25:181-189)

ISSN:0090-3493    

出版商:OVID    

年代:1997

数据来源: OVID

摘要:

ObjectiveTo evaluate a system for delivery of inhaled nitric oxide.DesignProspective, laboratory study.SettingEngineering laboratory.SubjectsA standard ventilator (Servo Ventilator 300), supplemented with extra gas modules for nitric oxide delivery.InterventionsTwo ventilator-integrated gas modules, delivering <or=to10 parts per million (ppm) or <or=to100 ppm of nitric oxide, were used in adult and neonatal modes during volume-controlled ventilation. Set nitric oxide concentration and FIO sub 2 were systematically changed and compared with the measured concentration. Short-term mixing was tested in adult, pediatric, and neonatal modes by substituting nitric oxide with CO2, and measuring the delivered concentration by a fast-response CO2analyzer during five successive respiratory cycles. Long-term mixing was tested with the administration of 25 ppm of nitric oxide for 7 days.Measurements and Main ResultsDelivered concentration of nitric oxide and nitrogen dioxide were simultaneously measured at the Y-piece by two methods-chemiluminescence and electrochemical fuel cells. The maximum absolute difference between set and measured concentrations of nitric oxide in the adult mode was 0.6 ppm at a set concentration of 10 ppm and 2.7 ppm at a set concentration of 100 ppm. In the neonatal mode, the maximal difference was 3.1 ppm at a set concentration of 100 ppm. Nitrogen dioxide concentration increased with increasing concentration of nitric oxide and oxygen to 2.6 ppm (as measured by the chemiluminescence analyzer) and 3.6 ppm (as measured by the electrochemical fuel cell), at a setting of 100 ppm of nitric oxide with an FIO2of 0.90 in the neonatal mode (2 L/min). During the short-term test of mixing stability throughout the respiratory cycles, a constant set CO2concentration varied maximally by +/- 6.2% from the set value in the neonatal mode, whereas the variance was by +/- 6.5% in pediatric mode, and by +/- 8.0% in the adult mode. During the long-term test, nitric oxide concentration varied maximally by +/- 2.6% (as measured by the chemiluminescence analyzer) and by +/- 2.3% (as measured by the electrochemical fuel cell).ConclusionsAn accurate precision in delivered nitric oxide concentration was achieved during intermittent flow ventilation, and this accuracy was independent of tested ventilator settings. The delivery system administered an almost stable concentration throughout a respiratory cycle and during long-term delivery. If the mixing point is in the inspiratory part of the ventilator, valid measurement of nitric oxide and nitrogen dioxide delivery concentrations are possible. Both techniques for measuring nitric oxide and nitrogen dioxide have drawbacks. (Crit Care Med 1997; 25:190-196)

ISSN:0090-3493    

出版商:OVID    

年代:1997

数据来源: OVID

摘要:

ObjectiveTo describe a 10-yr experience with an end-of-life practice in a hospital.DesignA nonexperimental, prospective, descriptive design was used to record variables from a convenience sample of patients transferred to the Comprehensive Supportive Care Team.SettingDetroit Receiving Hospital is an urban, university-affiliated, Level I trauma/emergency hospital.PatientsPatients who are not expected to survive hospitalization, and for whom a decision has been made to focus care on palliative interventions, are candidates for care by this practice.InterventionsNone.Measurements and Main ResultsPatient demographics, including the following information: age; gender; diagnoses; illness severity; mortality rate; and disposition. Measures of resource utilization included: referral sources; Therapeutic Intervention Scoring System values; bed costs; and length of hospital stay.Satisfactory patient/family care with a measurable reduction in the use of resources can be achieved in the hospital setting.ConclusionsA hands-on approach to the care of dying patients by this specialty, palliative care service has provided patients, families, and clinicians with the type of support needed for satisfactory end-of-life care. A summary of our experience may be useful to others. (Crit Care Med 1997; 25:197-202)

ISSN:0090-3493    

出版商:OVID    

年代:1997

数据来源: OVID

ISSN:0090-3493    

出版商:OVID    

年代:1997

数据来源: OVID

ISSN:0090-3493    

出版商:OVID    

年代:1997

数据来源: OVID

ISSN:0090-3493    

出版商:OVID    

年代:1997

数据来源: OVID

ISSN:0090-3493    

出版商:OVID    

年代:1997

数据来源: OVID