摘要:

ObjectiveTo demonstrate the efficacy and safety of an updated version of the nasal ``bridle,'' which is used to prevent the accidental removal of small-bore nasoenteric feeding tubes.DesignA descriptive study.SettingSurgical intensive care unit in a tertiary care hospital.PatientsTwenty-six critically ill patients without nasotracheal tubes or facial trauma or fractures who received enteral nutrition and either had removed or were at risk for removing their properly positioned nasoenteric feeding tubes.InterventionsA length of one-eighth inch (3.2 mm) umbilical tape is looped around the nasal septum and vomer by serially attaching the ends of the umbilical tape to a suction catheter, passing the catheter through the nostrils into the oropharynx, and retrieving the ends from the oropharynx. The properly positioned umbilical tape loops into one nostril, around the vomer, and out the other nostril. The feeding tube is then anchored to the umbilical tape with a central venous catheter fastener clamp.Measurements and Main ResultsCommunicative patients denied discomfort, and there were no episodes of bleeding, infection, sinusitis, or nasal septal trauma caused by the umbilical tape bridle. Five patients had the bridle in place more than 30 days. There were only two cases in which the bridle failed to prevent removal of a feeding tube. One of these cases occurred because the fastener clamp anchor failed, but this patient had had the same bridle and feeding tube for 170 consecutive days.ConclusionsAn umbilical tape bridle with a central venous catheter fastener clamp anchor is a safe and effective method to prevent the accidental removal of nasoenteric feeding tubes in critically ill patients. We recommend its use in confused or uncooperative patients, or when the risk of unintentional feeding tube removal is high.(Crit Care Med 1996; 24:429-431)

ISSN:0090-3493    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

ObjectivesTo estimate the potential for solid organ donation; to identify modifiable reasons for nondonation.DesignRetrospective medical records review.SettingSixty-nine acute care hospitals in four geographic areas of the United States in 1990, and a stratified random sample of 89 hospitals in three of the same areas and 33 of the same hospitals in 1993.PatientsPatients less than equals 70 yrs of age who were brain dead and medically suitable for donation.InterventionsNone.Measurements and Main ResultsStandard forms were used to record patient demographic and hospital information. Reasons for nondonation were coded as ``not identified,'' ``family not asked,'' ``consent denied,'' or ``other.'' The main outcome measures were rate of donation and rates of nonidentification, not asking, and nonconsent. Organ donation occurred among 33% (299/916) of medically suitable cases identified in 1990 (95% confidence interval 30% to 36%). Ninety-four potential donors were not identified, 156 were not asked, 326 families denied consent, and 41 potential donors were categorized as ``other,'' including patients who had suffered a cardiac arrest, and medical examiner prohibition of donation. In the 1993 study, organ donation occurred in an estimated 33% of suitable cases. In 1990, rates of donation were highest among patients less than 50 yrs of age, patients who died of traumatic causes, and non-Hispanic white patients. Logistic regression showed lower odds of donation for African American patients (odds ratio 0.38, 95% confidence interval 0.23 to 0.63) independent of potentially confounding hospital and patient variables (p equals .0001). Donation rates did not vary by hospital size or type.ConclusionsDespite legal and policy initiatives, only one third of potential donors became donors in 1990, with similar results in 1993. Extrapolating the 1990 findings to the United States suggests a pool of 13,700 medically suitable donors per year. Prospective identification and requesting donation in all suitable potential donor cases could lead to 1,800 additional donors per year.(Crit Care Med 1996; 24:432-439)

ISSN:0090-3493    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

ObjectivesReconstituted human high-density lipoprotein (HDL) can inhibit lipopolysaccharide effects in vivo. The major objectives of this study were to characterize the pharmacokinetics of reconstituted HDL in a stressed large-animal model and to provide preclinical tolerance information in support of use of reconstituted HDL in humans.DesignA randomized, blinded, placebo-controlled trial where each animal received either reconstituted human HDL at a dose of 100 mg/kg (apolipoprotein A-I) or placebo, immediately after hemorrhagic shock and resuscitation.SettingAnimal laboratory.SubjectsTwelve immature female swine (18 to 25 kg) were studied.InterventionsSix to 8 days before shock and study drug administration, animals were anesthetized and catheters were placed in the external jugular vein and abdominal aorta. These catheters were secured to the dorsal surface. On the day of shock, the animals were sedated (alpha-chloralose) and 50 mL/kg of arterial blood was removed over 0.5 hr. One half hour after blood removal, shed blood was infused, which was immediately followed by study drug (reconstituted HDL or placebo), and then by 1 L of lactated Ringer's solution.Measurements and Main ResultsPhysiologic (arterial blood pressure, heart rate, respiratory rate) and laboratory (serum chemistries, hematologic and coagulation studies, and blood gases) measurements were determined intermittently for 96 hrs after the induction of shock. Blood was collected intermittently for 48 hrs after shock for assay of apolipoprotein A-I and phosphatidylcholine in plasma.Reconstituted HDL was well tolerated and did not appear to alter the physiologic responses to shock and resuscitation.HDL transient increase in aspartate aminotransferase concentration was noted in the reconstituted group but this increase normalized by 24 hrs after drug administration. Mean apolipoprotein A-I pharmacokinetic parameters were as follows: half-life 24.5 plus minus 5.3 (SD) hrs; clearance 41.9 plus minus 10 mL/hr; and volume of distribution 1.39 plus minus 0.08 L. The apparent mean half-life of phosphatidylcholine was 5.4 plus minus 0.8 hrs.ConclusionsReconstituted human HDL was well tolerated in animals that had undergone hemorrhagic shock with resuscitation. The apolipoprotein component of reconstituted HDL had a relatively long half-life, with distribution limited to the vascular space. These findings support the investigational use of this product in humans.(Crit Care Med 1996; 24:440-444)

ISSN:0090-3493    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

ObjectivesPancreatic hypoxia/ischemia, as a consequence of shock-induced microcirculatory failure, is considered a causative facter in the initiation and/or progression of pancreatic tissue injury. The aim of this study was to compare the effects of ``small-volume resuscitation'' with conventional isovolemic colloid and hypervolemic crystalloid resuscitation on pancreatic microcirculation after hemorrhagic shock.DesignRandomized, controlled intervention trial.SettingUniversity laboratory.SubjectsTwenty-three male Sprague-Dawley rats anesthetized with a-chloralose and mechanically ventilated.InterventionsRats subjected to 1 hr of hemorrhagic shock (mean arterial pressure of 40 mm Hg) were resuscitated with lactated Ringer's solution (four-fold shed volume/20 mins), 10% hydroxyethyl starch (shed volume/5 mins), or 7.2% sodium chloride-10% hydroxyethyl starch (10% shed volume/2 mins).Measurements and Main ResultsThe microcirculation of pancreatic acinar tissue was studied by means of intravital fluorescence microscopy and laser Doppler flowmetry. At 1 hr after resuscitation, mean arterial pressure, pancreatic capillary erythrocyte velocity, and erythrocyte flux were found to be significantly increased when compared with those values in the shock state. However, mean arterial pressure, pancreatic capillary erythrocyte velocity, and erythrocyte flux did not completely return to preshock values, regardless of the type of fluid used for resuscitation. At 15 mins and 1 hr after resuscitation, shock-induced capillary perfusion failure (reduction of functional capillary density) was restored to 91% to 94% of baseline values in all groups. Pancreatic capillary narrowing, indicating microvascular endothelial cell swelling, was abolished by resuscitation with both isotonic hydroxyethyl starch and hypertonic hydroxyethyl starch (p less than .05 vs. lactated Ringer's solution).ConclusionsDespite replacement of only 10% of actual blood loss, small-volume resuscitation with hypertonic hydroxyethyl starch is as effective as the ten-fold volume of isotonic hydroxyethyl starch and, due to prevention of microvascular endothelial cell swelling, superior to the 40-fold volume of isotonic lactated Ringer's solution in regard to restoration of the shock-induced microcirculatory disturbances of rat pancreatic acinar tissue.(Crit Care Med 1996; 24:445-450)

ISSN:0090-3493    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

ObjectiveTo determine if high-frequency external chest wall vibration added to low flow intratracheal fresh gas insufflation alters the intra-airway CO2distribution and the resistance to CO2transport from the lungs.DesignProspective study.SettingExperimental laboratory.SubjectsSix adult anesthetized and paralyzed mongrel dogs (mean weight 24.3 plus minus 4.4 kg).InterventionsDogs were ventilated by three methods: a) intermittent positive pressure ventilation; b) intermittent positive pressure ventilation with tracheal insufflation of fresh gas (FIO2of 0.4) flowing at 0.15 L/kg/min through a catheter positioned at the carina; and c) intermittent positive pressure ventilation with tracheal insufflation and with external high-frequency chest wall vibration of the dependent hemithorax.Measurements and Main ResultsWe measured arterial blood gas values as an index of global gas exchange, and intrapulmonary airway CO2concentrations as an index of local gas exchange. Intra-airway CO2concentrations along the axis of the airways were measured via a sampling catheter. Airway axial concentration profiles were constructed and resistances to gas transport were calculated from the measured data. Vibration increased intraluminal CO2concentrations from 1.1% to 2.5% mouthward of the insufflation catheter tip. Peak resistance to CO2transport decreased by 65% during vibration relative to the insufflation-only value. Vibration displaced peak transport resistance from second- to fourth-generation airways.ConclusionsGlobal gas exchange improves during ventilation by chest wall vibration with low flow insufflation. Local gas exchange in the central airways is also improved due to increased intraluminal mixing and CO2elimination. This ventilation technique may confer therapeutic advantages over conventional mechanical ventilation in the treatment of ventilatory failure.(Crit Care Med 1996; 24:451-457)

ISSN:0090-3493    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

ObjectivesTo determine the efficacy of tracheal gas insufflation delivered by two different catheter designs on CO2elimination when used in conjunction with high-frequency oscillatory ventilation.DesignA nonrandomized before and after trial. Each animal served as his own control.SubjectsTen mongrel dogs weighing 20.9 plus minus 1.9 kg. Four animals were assigned to a normal lung group and six animals underwent lung injury by large volume saline lavage.InterventionPermissive hypercapnia was allowed to occur by selecting oscillator settings that would lead to alveolar hypoventilation. Proximal mean airway pressure was kept constant. Tracheal gas was insufflated at 1 cm above the carina for 30-min periods at gas flows of 5 to 15 L/minMeasurements and Main ResultsCarinal pressure, hemodynamic parameters (cardiac output, mean arterial pressure, pulmonary arterial pressure, pulmonary artery occlusion pressure), and gas exchange parameters (PaCO2, PaO2, PaO2/FIO2, shunt fraction, DO2) were measured.For the normal dogs, at catheter flow of 15 L/min, the forward thrust catheter increased carinal pressure and PaO sub 2/FIO sub 2 by 30% (p less than .003) and 105% (p less than .005), respectively. The forward thrust catheter reduced PaCO2by 40% (p less than .04). The reverse thrust catheter increased PaO2/FIO2by 102% (p less than .001) and decreased carinal pressure and PaCO2by 44% (p less than .001) and 34% (p less than .003), respectively. For the injured dogs, at catheter flow rate of 15 L/min, the forward thrust catheter increased carinal pressure, PaO2, and PaO2/FIO2by 6% (p less than .001), 23% (p less than .001) and 24% (p less than .02), respectively. The forward thrust catheter reduced PaCO2by 29% (p less than .002). The reverse thrust catheter increased PaO2and PaO2/FIO2both by 11% (p less than .02) and reduced carinal pressure and PaCO2by 23% (p less than .001) and 18% (p less than .002), respectively.ConclusionsTracheal gas insufflation is capable of improving oxygenation and ventilation in acute lung injury when combined with high-frequency oscillatory ventilation. The addition of this second gas flow at the level of the carina raises or lowers distal airway pressure, the magnitude of which is dependent on the direction and rate of gas flow. The beneficial effects of tracheal gas insufflation may be tempered by the long-term effects of altering distal airway pressure; lowering distal airway pressure may lead to atelectasis, whereas raising distal airway pressure may lead to an auto-positive end-expiratory pressure (auto-PEEP) effect.(Crit Care Med 1996; 24:458-465)

ISSN:0090-3493    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

ObjectiveTo compare the effectiveness of perfluorocarbon-associated gas exchange to volume controlled positive pressure breathing in supporting gas exchange, lung mechanics, and survival in an acute lung injury model.DesignA prospective, randomized study.SettingA university medical school laboratory approved for animal research.SubjectsNeonatal piglets.InterventionsEighteen piglets were randomized to receive perfluorocarbon-associated gas exchange with perflubron (n equals 10) or volume controlled continuous positive pressure breathing (n equals 8) after acute lung injury was induced by oleic acid infusion (0.15 mL/kg iv).Measurements and Main ResultsArterial and venous blood gases, hemodynamics, and lung mechanics were measured every 15 mins during a 3-hr study period. All animals developed a metabolic and a respiratory acidosis during the infusion of oleic acid. Following randomization, the volume controlled positive pressure breathing group developed a profound acidosis (p less than .05), while pH did not change in the perfluorocarbon-associated gas exchange group. Within 15 mins of initiating perfluorocarbon-associated gas exchange, oxygenation increased from a PaO2of 52 plus minus 12 torr (6.92 plus minus 1.60 kPa) to 151 plus minus 93 torr (20.0 plus minus 12.4 kPa) and continued to improve throughout the study (p less than .05). Animals that received volume controlled positive pressure breathing remained hypoxic with no appreciable change in PaO2. Although both groups developed hypercarbia during oleic acid infusion, PaCO2steadily increased over time in the control group (p less than .01). Static lung compliance significantly increased postrandomization (60 mins) in the animals supported by perfluorocarbon-associated gas exchange (p less than .05), whereas it remained unchanged over time in the volume controlled positive pressure breathing group. However, survival was significantly higher in the perfluorocarbon-associated gas exchange group with eight (80%) of ten animals surviving the entire study period. Only two (25%) of the eight animals in the volume controlled positive pressure breathing group were alive at the end of the study period (log-rank statistic, p equals .013).ConclusionsPerfluorocarbon-associated gas exchange enhanced gas exchange, pulmonary mechanics, and survival in this model of acute lung injury.(Crit Care Med 1996; 24:466-474)

ISSN:0090-3493    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

ObjectivesWe hypothesized that: a) perfluorocarbon-associated gas exchange could be accomplished in normal large sheep; b) the determinants of gas exchange would be similar during perfluorocarbon-associated gas exchange and conventional gas ventilation; c) in large animals with lung injury, perfluorocarbon-associated gas exchange could be used to enhance gas exchange without adverse effects on hemodynamics; and d) the large animal with lung injury could be supported with an FIO2of less than 1.0 during perfluorocarbon-associated gas exchange.DesignProspective, observational animal study and prospective randomized, controlled animal study.SettingAn animal laboratory in a university setting.SubjectsThirty adult ewes.Measurements and Main ResultsFive normal ewes (61.0 plus minus 4.0 kg) underwent perfluorocarbon-associated gas exchange to ascertain the effects of tidal volume, end-inspiratory pressure, and positive end-expiratory pressure (PEEP) on oxygenation. Respiratory rate, tidal volume, and minute ventilation were studied to determine their effects on CO2clearance. Sheep, weighing 58.9 plus minus 8.3 kg, had lung injury induced by instilling 2 mL/kg of 0.05 Normal hydrochloric acid into the trachea. Five minutes after injury, PEEP was increased to 10 cm H2O. Ten minutes after injury, sheep with PaO2values of less than 100 torr (less than 13.3 kPa) were randomized to continue gas ventilation (control, n equals 9) or to institute perfluorocarbon-associated gas exchange (n equals 9) by instilling 1.6 L of unoxygenated perflubron into the trachea and resuming gas ventilation. Blood gas and hemodynamic measurements were obtained throughout the 4-hr study.Both tidal volume and end-inspiratory pressure influenced oxygenation in normal sheep during perfluorocarbon-associated gas exchange. Minute ventilation determined CO2clearance during perfluorocarbon-associated gas exchange in normal sheep. After acid aspiration lung injury, perfluorocarbon-associated gas exchange increased PaO2and reduced intrapulmonary shunt fraction. Hypoxia and intrapulmonary shunting were unabated after injury in control animals. Hemodynamics were not influenced by the institution of perfluorocarbon-associated gas exchange.ConclusionsTidal volume and end-inspiratory pressure directly influence oxygenation during perfluorocarbon-associated gas exchange in large animals. Minute ventilation influences clearance of CO2. In adult sheep with acid aspiration lung injury, perfluorocarbon-associated gas exchange at an FIO2of less than 1.0 supports oxygenation and improves intrapulmonary shunting, without adverse hemodynamic effects, when compared with conventional gas ventilation.(Crit Care Med 1996; 24:475-481)

ISSN:0090-3493    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

ObjectiveTo study the role of nitric oxide in the cardiovascular response to a model of a low output syndrome.DesignProspective animal study.SettingAnimal research laboratory.SubjectsSheep anesthetized with pentobarbital, mechanically ventilated, and monitored with pulmonary arterial and peripheral arterial catheters.InterventionsA low output state was induced by inflating a balloon-tip catheter placed in the right atrium. Cardiac index was maintained at 1 L/min/m2throughout the experiment in three groups of sheep: a) control (n equals 6); b) LNNA group (pretreated with the nitric oxide synthase inhibitor Nomega-nitro-L-arginine [LNNA, 100 mg/kg, iv bolus, n equals 6]); and c) dexamethasone group (pretreated with dexamethasone (6 mg/kg, intravenous bolus, n equals 6). Dexamethasone is an inhibitor of the induction of nitric oxide synthase. LNNA or dexamethasone were administered 15 mins before inducing the low output state.Measurements and Main ResultsHemodynamic and oxygen transport variables, and plasma lactate and pyruvate concentrations, were measured at baseline and during the next 3 hrs. For a comparable decrease in cardiac index and oxygen delivery in all groups, the LNNA group had less hypotension and a more marked increase in systemic vascular resistance as compared with the control group. Oxygen consumption and oxygen extraction were higher in the LNNA group as compared with the control group at 30 and 60 mins. Plasma lactate concentration increased significantly less in the LNNA group than in the control and the dexamethasone groups during the observation period.ConclusionsInhibition of nitric oxide synthesis during a severe low output state in sheep is associated with a better hemodynamic response, as evidenced by a greater vasoconstriction, and signs of less marked tissue hypoxia. It is likely that inhibition of nitric oxide synthesis in this model leads to an imbalance between the tonic relaxing action of nitric oxide and the influences of vasoconstrictor agents.(Crit Care Med 1996; 24:482-487)

ISSN:0090-3493    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

ObjectiveTo compare the effects of surfactant replacement by aerosol inhalation and bolus instillation on acute lung injury caused by the intratracheal injection of endotoxin in rats.DesignProspective, randomized study.SettingUniversity laboratory.SubjectsMale Wistar rats weighing 368 plus minus 31 (SD) g.InterventionsEscherichia coli endotoxin (57 plus minus 20 mg/kg) was injected into the tracheas of 36 anesthetized and mechanically ventilated rats (FIO2of 1.0). When the PaO2had decreased to less than 200 torr (less than 26.7 kPa), the rats were randomly assigned to one of three groups: a control group (n equals 12) given no material; a bolus group (n equals 12) given a modified natural surfactant suspension (100 mg/kg in 2.0 mL/kg saline) by bolus instillation into the trachea; and an aerosol group (n equals 12) given surfactant aerosolized with an ultrasonic nebulizer for 60 mins.Measurements and Main ResultsBolus instillation transiently decreased the mean blood pressure by approximate 30%. However, aerosol inhalation did not. The PaO2values of the control group remained less than 90 torr (less than 12.0 kPa) until the end of the experiment (180 mins). In contrast, the PaO2of the bolus group increased to 387 plus minus 134 torr (51.6 plus minus 17.9 kPa; p less than .05 vs. other groups) 15 mins after surfactant replacement, and remained at approximate 400 torr (approximate 53.3 kPa) throughout the experiment. The PaO2values of the aerosol group increased slowly, peaked at 240 plus minus 109 torr (32.0 plus minus 14.5 kPa; p less than .05 vs. the control group) 60 mins after the start of surfactant replacement, and remained at approximate 200 torr (approximate 26.7 kPa).ConclusionsBolus instillation was superior to aerosol inhalation concerning maximum efficacy, the rapid onset of therapeutic effects, and the necessary dose of surfactant. However, aerosol inhalation that does not cause hypotension may be of use in the treatment of adult respiratory distress syndrome in patients with circulatory instability.(Crit Care Med 1996; 24:488-494)

ISSN:0090-3493    

出版商:OVID    

年代:1996

数据来源: OVID