摘要:

ObjectiveTo examine the hemodynamic effects and the oxygen transport pattern of autotransfusion of unprocessed blood on hemodynamics and oxygen transportation.DesignProspective, observational study.SettingResearch laboratory of a university medical center.SubjectsSix healthy, domestic pigs (20 to 33 kg).InterventionsA left thoracotomy was performed and a 5-mm incision was created in the descending aorta, resulting in a controlled hemorrhage of 30 mL/kg (approximate 40% of blood volume) into the thoracic cavity over a 45-min time period. During that period, mean arterial pressure (MAP) was maintained slightly more than 50 mm Hg, using intravenous lactated Ringers' solution. The blood sample was collected from the open thorax with compresses soaked in citric acid solution and then extracted by manual squeezing, filtered through several layers of gauzes, and stored in glass bottles. Repeat measurements were performed after hemorrhage, after retransfusion of the harvested blood, and thereafter every 15 mins up to 60 mins. The animals were supported for 2 more hrs and were observed for the following 48 hrs.Measurements and Main ResultsAll animals survived and were in good condition 48 hrs after the experimental hemorrhage. The circulatory and oxygen transport response at the end of hemorrhage and concomitant maintenance of blood pressure at more than 50 mm Hg resulted in: significant reductions of cardiac index, MAP, and oxygen transport (overdot DO2) (46%, 50%, and 64% reductions, respectively, p less than .01), in an increase of heart rate (HR) (plus 21%, not significant), pulmonary vascular resistance index (plus 112%, p less than .05), and oxygen extraction (plus 105%, p less than .01), as well as in a nonsignificant decrease of systemic vascular resistance index (minus 8%).After autotransfusion, the basic hemodynamic variables, MAP and HR were corrected, remaining near baseline (not significant) afterward. Cardiac index and overdot DO sub 2 increased after autotransfusion, but remained below the baseline until the end of the study protocol (p less than .05). A significant increase was noticed for pulmonary arterial pressure and pulmonary vascular resistance index immediately after autotransfusion (p less than .01). These values were corrected in part after 15 to 30 mins, but remained higher throughout the observation period compared with baseline (29.5% and 89.8%, respectively, p less than .05).The recently introduced relationship between cardiac index and oxygen extraction has been proposed to avoid problems of mathematical coupling between oxygen consumption and overdot DO sub 2 measurements. This relationship followed a similar course in all experiments throughout each phase. A shift downward and to the right represented the endpoint of the hemorrhagic phase. After autotransfusion, a shift toward baseline was noticed.Prothrombin time and partial thromboplastin time remained unchanged after autotransfusion. Free hemoglobin concentrations increased immediately after autotransfusion (plus 33%, p less than .05), but returned to baseline values 48 hrs later. Histologic examination showed no changes in the examined organs.ConclusionsReinfusion of large amounts of unprocessed blood (up to 40% of blood volume), collected with compresses from a noncontaminated surgical field is a cheap method, which may be of potential benefit in trauma patients, when more sophisticated autotransfusion devices are lacking. In the present study, this method resulted in transient but significant hemodynamic changes in the pulmonary circulation. Impairment of oxygen transport was noticed after the end of hemorrhage, but this impairment cannot be attributed to the autotransfusion technique alone, but also to factors such as hemorrhagic shock, surgical trauma, etc.(Crit Care Med 1996; 24:855-861)

ISSN:0090-3493    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

ObjectiveTo examine the effect of FIO2on the contents of total protein, total phospholipids, phosphatidylcholine, and phosphatidylglycerol in the bronchoalveolar lavage-accessible space in male and female rats in vivo.DesignProspective, controlled trial.SettingResearch laboratory.SubjectsAdult male and female Sprague-Dawley rats.InterventionsAfter animals were anesthetized with an intraperitoneal injection of pentobarbital (50 mg/kg), a 24-gauge catheter was placed in the femoral artery. Determinations of arterial pH and PaO2and PaCO2were performed before tracheostomy, and all animals were then ventilated for 3 mins with an FIO2of 0.21, followed by a reduction bronchoalveolar lavage. The animals were randomly divided equally by gender and given either an FIO2of 0.21, 0.50, or 1.00. All subjects were ventilated in the same manner. Sampling bronchoalveolar lavage was performed 80 and 160 mins after institution of the variable FIO2. Bronchoalveolar lavage samples were analyzed for protein and phospholipid content. Arterial blood was obtained for determination of arterial pH and the PaO2and PaCO2immediately and 40 mins after each sampling bronchoalveolar lavage.Measurements and Main ResultsAt the times of bronchoalveolar sampling lavage, the PaCO2increased and the PaO2decreased, as did the pH. In the 40-min samples obtained between sampling lavages, the arterial pH and PaCO2and PaO sub 2 returned to pretracheostomy values (animals ventilated with an FIO2of 0.21) and/or higher po2values (animals ventilated with an FIO2of 0.5 or 1.0).No differences were found between genders in amounts of total protein and phospholipid content in reduction and zero time bronchoalveolar lavage fluid. Males and females ventilated with an FIO2of 0.21 differed in the amounts of total protein, total phospholipids, phosphatidylcholine, and phosphatidylglycerol found in sampling bronchoalveolar lavage at 80 and 160 mins. Amounts of total protein and total phospholipids also demonstrated gender differences with the administration of an FIO2of 1.0, but no differences were found with the administration of an FIO2of 0.5. In terms of the phospholipids, males had greater amounts in the sampling bronchoalveolar lavage at 80 mins, and females at 160 mins. Administration of an FIO2of 0.5 or 1.0 resulted in decreased amounts of total phospholipids in both males and females when compared with an FIO2of 0.21. In males, administration of both FIO2of 0.5 and 1.0 resulted in decreased amounts of phosphatidylcholine found in the bronchoalveolar lavage-accessible space; in females, amounts of phosphatidylcholine were only decreased when an FIO2of 1.0 was administered. In males, administration of an FIO2of 1.0 also resulted in decreased amounts of phosphatidylglycerol. The decreased amount of phosphatidylglycerol occurred in females given an FIO2of 0.5. Amounts of total protein in males and females given an FIO2of 0.5 and in females given an FIO2of 1.0 were found to be increased.ConclusionsOur findings support the hypothesis that hyperoxia alters surfactant composition. Further investigation is warranted to determine the mechanisms affecting secretion of phosphatidylcholine and phosphatidylglycerol into the bronchoalveolar space and to explore the gender difference in secretion.(Crit Care Med 1996; 24:862-869)

ISSN:0090-3493    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

ObjectivesTo assess albuterol delivery by metered-dose inhaler in a mechanically ventilated pediatric lung model and to determine the influence of the following variables on albuterol delivery: endotracheal tube diameter; type of spacer; humidification; and pulmonary mechanics.DesignProspective, in vitro, laboratory study.SettingResearch laboratory.InterventionsA model, consisting of a volume-cycled ventilator, pediatric breathing circuit, 4.0- or 6.0-mm endotracheal tube, and lung simulator, was assembled. Ventilator settings were: tidal volume 250 mL; FIO20.5; inspiration/expiration ratio 1:3; respiratory rate 25 breaths/min; positive end-expiratory pressure 3 cm H2O; temperature 35 degrees C; and a decelerating flow pattern, using dry and humidified air. Lung simulator compliance and resistance values were consistent with those values reported for healthy children (20 mL/cm H2O and 40 cm H2O/L/sec) and children with pulmonary disease (10 mL/cm H2O and 60 cm H2O/L/sec). Pulmonary mechanics were verified with a pulmonary function diagnostic system. Ten metered-dose inhaler canisters were used to administer 2000 micro gram of albuterol, using either a collapsible or a rigid spacer. A circuit filter placed immediately proximal to the test lung collected drug exiting the endotracheal tube. The filter was rinsed with water and albuterol concentrations were determined by highperformance liquid chromatography. Each variable was tested in triplicate.Measurements and Main ResultsAlbuterol delivery was significantly (p less than equals .05) greater for the 6.0-mm endotracheal tube, rigid spacer, dry air, and pulmonary disease mechanics by multifactor analysis of variance. Drug delivery in humidified air with pulmonary disease mechanics using the rigid chamber was 2.5 plus minus 0.27% and 6.3 plus minus 0.99% for the 4.0- and 6.0-mm endotracheal tubes, respectively.ConclusionsThese in vitro results suggest that pulmonary disease mechanics and a 6.0-mm endotracheal tube improve albuterol delivery. Future clinical investigations in intubated pediatric patients with pulmonary disease are needed to address the clinical significance of these results.(Crit Care Med 1996; 24:870-874)

ISSN:0090-3493    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

ObjectiveTo identify factors in pediatric intensive care unit (ICU) patients that are associated with an increased risk of nosocomial infections.DesignA prospective, 1-yr cohort study.SettingA 16-bed pediatric ICU in a multidisciplinary, regional referral center.SubjectsAll patients admitted to the pediatric ICU.InterventionsNone.Measurements and Main ResultsThe primary outcome variable was the development of nosocomial infection.Out of 945 consecutive admissions, 75 patients developed 96 nosocomial infections. The most frequent infection sites were the lower respiratory tract (35%), the bloodstream (21%), and the urinary tract (21%). The most common organisms isolated were Gram-negative bacteria (53%), Gram-positive bacteria (27%), and fungi (9%). Variables significantly associated with the development of nosocomial infections included age, weight, Pediatric Risk of Mortality (PRISM) score, device utilization ratio, antimicrobial therapy, histamine-2 (H2) receptor blocker use, immune status, parenteral nutrition, and length of stay. When combined in a multivariate logistic regression model, the significant variables were operative status, PRISM score, device utilization ratio, antimicrobial therapy, parenteral nutrition, and length of stay before the onset of infection. The area under the receiver operating characteristic curve was 0.868. At a probability of 0.15, the sensitivity was 66.67%, and the specificity was 87.82%.ConclusionsPatients at risk for developing nosocomial infection can be identified using a multivariate logistic regression model with a high degree of sensitivity and specificity. These data indicate that institutional nosocomial rates need to be adjusted for risk factors. This model could help target patients at high risk for developing nosocomial infections for preventive strategies.(Crit Care Med 1996; 24:875-878)

ISSN:0090-3493    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

ObjectiveTo determine the bedside accuracy of direct patient pressure monitoring when used with new and clinically used disposable blood pressure (BP) transducers.DesignProspective study.SettingLaboratory bench and critical care units in an adult and children's hospital.SubjectsSeventy-five bedside patient monitors (25 Marquette Electronics, 25 Spacelab Medical, and 25 Hewlett-Packard), and 100 disposable transducers (50 from Utah Medical Products and 50 from Abbott Critical Care Systems [25 new, 25 clinically used of each manufacturer]) were tested.InterventionsNone.Measurements and Main ResultsA plus minus 2% accuracy requirement for bedside monitors and the plus minus 3% American National Standards Institute accuracy standard for disposable BP transducers were used. To test the accuracy of the bedside monitors, a certified transducer simulator was used to apply 100 mm Hg to each bedside monitor. To test the accuracy of the disposable BP transducers, a very accurate (plus minus 0.05%) pneumatic dead weight tester was used to apply pressures to the transducer. A digital power supply and a 6 1/2 digit voltmeter were used. The average output of the bedside monitors when 100 mm Hg was applied was 99.90 plus minus 0.83 mm Hg, with the worst cases being 98 and 103 mm Hg. For all 100 disposable pressure transducers, the average output was 100.03 plus minus 0.55 mm Hg, with the worst cases being 98.53 and 101.36 when 100 mm Hg was applied. There was no important difference in the accuracy of the transducers obtained from the two vendors nor whether the transducers had been used clinically.ConclusionsAll disposable BP transducers tested were much more accurate than the American National Standards Institute standard for accuracy. Even the worst case transducers were twice as accurate as required by the American National Standards Institute standard. Only one bedside monitor was outside the plus minus 2% accuracy range (103 mm Hg). Based on these findings, this author recommends that fixed calibration disposable transducers and fixed calibration bedside pressure monitoring systems be used. The clinical risks of air embolism and infection from the calibrating mercury manometer and the complexity of the calibration task are the overriding factors for making these recommendations.(Crit Care Med 1996; 24:879-882)

ISSN:0090-3493    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

ObjectiveThis article analyzes, from a legal perspective, a recent phenomenon involving a clash between the values of attending medical personnel and the instructions of surrogate decision-makers acting on behalf of incompetent patients. Some hospitals have gone to court to challenge decisions by surrogates to continue life support for permanently unconscious or other gravely debilitated patients. Their claim has been that continuation of life support would be medically inappropriate and that the surrogates' decisions ought to be overridden. These petitions have thus far been rejected. The objective here is to explain those decisions and to predict the outcome of future, similar litigation.Data SourcesThe primary data are the judicial decisions and legislation accumulated since the Quinlan case in 1976, regarding the medical handling of dying medical patients.ConclusionsJudicial rejection of healthcare providers' claims in the decided cases is explainable under traditional guardianship principles. The explanation lies in surrogates' authority to make decisions in the best interests of incompetent patients, and in judicial reluctance to brand life preservation of nonsuffering patients as abusive or contrary to patient interests.At the same time, the author anticipates a change in judicial posture, as courts acknowledge the widespread antipathy of people toward being indefinitely preserved in a noncognitive status. Because the judicial approach to the handling of dying persons often seeks to replicate what the patient would have wanted, there is room to consider consensus preferences where the particular patient has never indicated any deviation from those preferences. Courts will eventually override surrogate decisions that do not conform to widely shared preferences for avoiding the indignity of permanent unconsciousness or other gravely debilitated states.(Crit Care Med 1996; 24:883-887)

ISSN:0090-3493    

出版商:OVID    

年代:1996

数据来源: OVID

ISSN:0090-3493    

出版商:OVID    

年代:1996

数据来源: OVID

ISSN:0090-3493    

出版商:OVID    

年代:1996

数据来源: OVID

ISSN:0090-3493    

出版商:OVID    

年代:1996

数据来源: OVID

ISSN:0090-3493    

出版商:OVID    

年代:1996

数据来源: OVID