摘要:

ObjectiveTo evaluate whether bilevel positive airway pressure, by actively assisting inhalation, more rapidly improves ventilation, acidemia, and dyspnea than continuous positive airway pressure (CPAP) in patients with acute pulmonary edema.DesignRandomized, controlled, double-blind trial.SettingEmergency department in a university hospital.PatientsTwenty-seven patients, presenting with acute pulmonary edema, characterized by dyspnea, tachypnea, tachycardia, accessory muscle use, bilateral rales, and typical findings of congestion on a chest radiograph.InterventionsIn addition to standard therapy, 13 patients were randomized to receive nasal CPAP (10 cm H2O), and 14 patients were randomized to receive nasal bilevel positive airway pressure (inspiratory and expiratory positive airway pressures of 15 and 5 cm H2O, respectively) in the spontaneous/timed mode that combines patient flow-triggering and backup time-triggering.Measurements and Main ResultsAfter 30 mins, significant reductions in breathing frequency (32 +/- 4 to 26 +/- 5 breaths/min), heart rate (110 +/- 21 to 97 +/- 20 beats/min), blood pressure (mean 117 +/- 28 to 92 +/- 18 mm Hg), and PaCO2(56 +/- 15 to 43 +/- 9 torr [7.5 +/- 2 to 5.7 +/- 1.2 kPa]) were observed in the bilevel positive airway pressure group, as were significant improvements in arterial pH and dyspnea scores (p < .05 for all of these parameters). Only breathing frequency improved significantly in the CPAP group (32 +/- 4 to 28 +/- 5 breaths/min, p < .05). At 30 mins, the bilevel positive airway pressure group had greater reductions in PaCO2(p = .057), systolic blood pressure (p = .005), and mean arterial pressure (p = .03) than the CPAP group. The myocardial infarction rate was higher in the bilevel positive airway pressure group (71%) compared with both the CPAP group (31%) and historically matched controls (38%) (p = .05). Duration of ventilator use, intensive care unit and hospital stays, and intubation and mortality rates were similar between the two groups.ConclusionsBilevel positive airway pressure improves ventilation and vital signs more rapidly than CPAP in patients with acute pulmonary edema. The higher rate of myocardial infarctions associated with the use of bilevel positive airway pressure highlights the need for further studies to clarify its effects on hemodynamics and infarction rates, and to determine optimal pressure settings. (Crit Care Med 1997; 25:620-628)

ISSN:0090-3493    

出版商:OVID    

年代:1997

数据来源: OVID

摘要:

ObjectiveTranspyloric small intestine feeding tube placement can be difficult and tedious. Currently accepted techniques are associated with disadvantages and risk. The purpose of this study is to describe the development of a new technique: bedside videoscopic placement using fiberoptics through the tube.DesignProspective, descriptive case study.SettingIntensive care unit in a teaching hospital.PatientsSubjects were divided into two groups: a) group 1: eight healthy volunteers (seven male, one female); b) group 2: nine critically ill patients (six male, three female; eight of these patients were intubated).InterventionsStandard 12-Fr (4.0-mm) feeding tubes (n = 19) were placed. Two patients from group 2 had feeding tubes placed on two separate occasions. The feeding tubes were inserted by the oral (n = 8) or nasal (n = 11) route under direct vision, using a 6.7-Fr (2.2-mm) fiberoptic scope through the feeding tube.Measurements and Main ResultsWe visualized enteric structures clearly through the feeding tube in all subjects and patients. Based on visual landmarks, we advanced the feeding tube through the pylorus and into the duodenum in all individuals. Transpyloric tube placement was confirmed videoscopically (n = 19) and radiographically (n = 18). In three subjects from group 1, the feeding tube entered the first part of the duodenum, while, in the remainder of the subjects, the tube passed into or beyond the second portion of the duodenum. In eight (73%) of 11 attempts on the nine critically ill patients from group 2, the feeding tubes were advanced to the distal duodenum or jejunum. The time required for placement in group 2 ranged from 2 to 43 mins (mean 18 +/- 12 [SD]). The feeding tubes remained in place 10 +/- 4 days and patients met their estimated caloric needs within 24 hrs. Residual volumes of nutrition in the small bowel were <5 mL. There were no documented episodes of aspiration.ConclusionThis new technique has the potential for rapid, accurate, and safe feeding tube placement in patients requiring nutritional support. (Crit Care Med 1997; 25:629-634)

ISSN:0090-3493    

出版商:OVID    

年代:1997

数据来源: OVID

摘要:

ObjectivesTo study the central and regional hemodynamics and oxygen consumption during acute hypovolemia and volume replacement with crystalloid and colloid solutions.DesignProspective, randomized, laboratory investigation.SettingClinical physiology department at a university hospital.SubjectsEighteen healthy male volunteers, between 21 and 35 yrs of age (mean 26).InterventionsCatheters were inserted in the cubital vein, brachial artery, pulmonary artery, thoracic aorta, right hepatic vein, and left renal vein for measurements of systemic arterial and pulmonary arterial pressures, total and central blood volumes, extravascular lung water, and the splanchnic (liver) and renal blood flow rates. The exchange of respiratory gases was measured, using the Douglas bag technique.Measurements were made before and after a venesection of 900 mL and again after the subjects had been randomized and received volume replacement with either 900 mL of Ringer's acetate solution 900 mL of albumin 5%, or 900 plus 900 mL of Ringer's solution.Measurements and Main ResultsWithdrawal of 900 mL of blood decreased cardiac output and the splanchnic and renal blood flow rates by between -16% and -20%. The oxygen uptake decreased by 13% in the whole body, while it remained unchanged in the liver and kidney. The systemic and pulmonary vascular resistances increased, while the extravascular lung water decreased. Autotransfusion of fluid from tissue to blood was indicated by hemodilution, which was most apparent in subjects showing only a minor change in peripheral resistance.Cardiac output, blood volume, and systemic vascular resistance were significantly more increased by infusion of 900 mL of albumin 5% than by 900 mL of Ringer's solution. However, infusion of 1800 mL of Ringer's solution increased the extravascular lung water and the pulmonary arterial pressures to significantly above baseline, while no significant difference from baseline was found after 900 mL of Ringer's acetate solution.ConclusionsWithdrawal of 900 mL of blood induces similar reductions in cardiac output as in the splanchnic and renal blood flow rates. A fluid shift from the extravascular to the intravascular fluid compartment might restore up to 50% of the blood loss. Optimal volume substitution with Ringer's solution can be effectuated by infusing between 100% and 200% of the amount of blood lost. (Crit Care Med 1997; 25:635-640)

ISSN:0090-3493    

出版商:OVID    

年代:1997

数据来源: OVID

摘要:

ObjectiveTo evaluate a new technique in which a hand-held external magnet is used to maneuver nasoenteral feeding tubes through the pylorus and into the duodenum.DesignProspective case series.SettingCritical care units and medical and surgical wards of a university-affiliated community hospital.PatientsThirty-five patients were entered into the study after the attending physician requested assistance in tube placement.InterventionsA standard 12-Fr, 114-cm flexible nasoenteral feeding tube was modified by inserting a small magnet into the distal tip. The tube was inserted per nares into the stomach, using traditional technique. Next, an external magnet was placed over the right upper abdominal quadrant, at the midclavicular line to attract the tube tip along the lesser curvature of the stomach, through the pyloric sphincter, and into the duodenum. Portable abdominal radiography performed immediately after the procedure confirmed the anatomic location of the tube tip.Measurements and Main ResultsForty-two intubations were performed in 35 patients (in seven patients, the tube had to be reinserted due to inadvertent removal or surgery). In 37 (88%) of 42 intubations, the tube was passed through the pyloric sphincter and into the duodenum on the first attempt. The mean procedure time was 15 +/- 9 mins (range 10 to 45). There were no complications related to the procedure during the study period.ConclusionsThis report describes a novel technique of enteral feeding tube placement, using external magnetic guidance. Transpyloric placement was achieved in 88% of cases. This rellable and convenient bedside method for rapid placement of the tube into the duodenum allows prompt and safe initiation of enteral nutrition. (Crit Care Med 1997; 25:641-645)

ISSN:0090-3493    

出版商:OVID    

年代:1997

数据来源: OVID

摘要:

ObjectiveTo investigate relationships between acute adrenergic stress, plasma catecholamine concentrations, and beta2-adrenergic receptors.DesignProspective, descriptive study.SettingEmergency medical service at a university hospital.PatientsTwenty-seven patients with out-of-hospital cardiac arrest (n = 11), myocardial infarction (n = 6), and angina pectoris (n = 10), and 12 control subjects.InterventionsNone.Measurements and Main ResultsMononuclear leukocyte beta2-adrenergic receptor density and affinity were measured in patients 15 mins after successful cardiopulmonary resuscitation and after the diagnosis of myocardial infarction or angina pectoris, respectively, and were measured as well in control subjects. Plasma concentrations of catecholamines, glucose, and lactate were simultaneously measured with heart rate and blood pressure. After cardiac arrest, the density of beta2-adrenergic receptors (1858 +/- 188 sites/cell [p < .01]), plasma epinephrine concentration (31,990 +/- 14,526 pg/mL [174.6 +/- 79.3 nmol/L] [p < .01]), heart rate (100 +/- 6 beats/min [p < .01]), glucose concentration (14.9 +/- 0.8 mmol/L [p < .01]), and lactate concentration (10.9 +/- 0.6 mmol/L [p < .01]) were increased in patients compared with those values in healthy controls.ConclusionAcute maximal stress, such as after cardiac arrest, is associated with an increase in the density of beta2-adrenergic receptors on mononuclear leukocytes derived from patients after successful cardiopulmonary resuscitation. (Crit Care Med 1997; 25:646-651)

ISSN:0090-3493    

出版商:OVID    

年代:1997

数据来源: OVID

摘要:

ObjectiveTo determine whether pretreatment with a 21-aminosteroid, U-74389G, can prevent subsequent DNA injury in bleomycin-exposed lungs.SubjectsThirty-six adult male Sprague-Dawley rats.DesignControlled animal laboratory investigation of DNA injury in vivo.InterventionsAnimals were treated with 21-aminosteroid (10 mg/kg) or vehicle and subsequently received intratracheal instillation of bleomycin (1.75 U) or normal saline.Measurements and Main ResultsTwenty-four hours after bleomycin exposure, the 21-aminosteroid-treated animals had decreased evidence of DNA injury, expressed as percentage of DNA fragmentation normalized to the control group (113.5 +/- 6 [SEM] vs. 132 +/- 3.9%, p <or=to .05), and activity of the DNA repair enzyme poly ADP-ribose synthetase (3.4 +/- 0.2 vs. 5.6 +/- 0.9 pmol nicotinamide adenine dinucleotide/min/mg protein, p <or=to .05). Only bleomycinexposed (+ vehicle) animals demonstrated significant evidence of increased DNA injury vs. the intratracheal saline-exposed control groups.ConclusionsThe 21-aminosteroid pretreatment decreases subsequent pulmonary DNA injury induced by bleomycin exposure. This finding is likely due to the 21-aminosteroid's iron-chelating and cell-permeating abilities, and suggests that these agents may be effective in other diseases where iron-dependent free radical reactions occur. (Crit Care Med 1997; 25:652-656)

ISSN:0090-3493    

出版商:OVID    

年代:1997

数据来源: OVID

摘要:

ObjectiveTo determine if sepsis, which is accompanied by both systolic and diastolic myocardial dysfunction, involves changes in myocardial collagen, as myocardial collagen changes can affect both myocardial compliance and contractility.DesignProspective, randomized, controlled study.SettingAnimal laboratory at a university-affiliated hospital.SubjectsMale Sprague-Dawley rats, weighing 310 to 396 g.InterventionsCecal ligation and perforation (to induce sepsis) for 24 (n = 9) or 48 hrs (n = 9); sham laparotomy for 24 (n = 10) or 48 hrs (n = 9) with saline fluid resuscitation or normal control (n = 5) groups.Measurements and Main ResultsCollagen content and interstitial space were determined, using polarized light microscopy and a computer video densitometry system. At 24 and 48 hrs post surgery, heart rate and cardiac index were increased, and systemic vascular resistance index was decreased significantly in the sepsis vs. the sham rats. Collagen content was decreased significantly in the sepsis vs. the sham groups both at 24 and 48 hrs following surgery (1.83 +/- 0.79 [SD] % [24 hrs], 1.76 +/- 0.31% [48 hrs] vs. 2.83 +/- 0.73% [24 hrs], 2.25 +/- 0.72% [48 hrs]; p < .01). Interstitial space was increased significantly in the sepsis vs. the sham groups (13.9 +/- 3.5% [24 hrs], 15.6 +/- 5.2% [48 hrs] vs. 8.6 +/- 4.2% [24 hrs], 9.9 +/- 4.8% [48 hrs]; p < .01).ConclusionsSepsis is accompanied by changes in myocardial collagen content and myocardial edema. These changes may contribute to the systolic and diastolic myocardial dysfunction, and particularly to the ventricular dilation, observed in sepsis. (Crit Care Med 1997; 25:657-662)

ISSN:0090-3493    

出版商:OVID    

年代:1997

数据来源: OVID

摘要:

ObjectiveTo evaluate the effects of dopexamine administration on hemodynamic variables and tissue oxygen tensions during crystalloid resuscitation from hemorrhagic shock.DesignRandomized, control trial.SettingAn animal laboratory at a university center.SubjectsTwelve piglets, mean weight 22 kg.InterventionsThe animals were anesthetized and bled to a state of hemorrhagic shock and resuscitated, using a crystalloid solution infused at a rate of [approximately]2.6 mL/min/kg (total amount 208 mL/kg). Cardiac output and mean arterial pressure (MAP) were measured as indicators of volume filling during the 20- to 30-min resuscitation period and during the follow-up period until 80 mins from the start of resuscitation.Dopexamine was administered by infusion at 6 micro g/kg [centered dot] min from the start of volume replacement (dopexamine group, n = 6). The rest of the animals (control group, n = 6) were given volume replacement only.Measurements and Main ResultsSystemic oxygen transport variables were calculated. Tissue oxygen tensions were continuously recorded from the liver, conjunctival layer, and via subcutaneous and transcutaneous electrodes in the abdominal region.MAP decreased from 119 +/- 2 (SEM) to 44 +/- 2 mm Hg and cardiac output decreased by 77% during the shock period. During resuscitation, cardiac output was restored in both groups. MAP increased close to the baseline during the early resuscitation period and decreased slowly during follow-up. Oxygen delivery remained at 46% of baseline, whereas systemic oxygen consumption was restored during resuscitation in both groups. Liver tissue oxygen tension increased well above baseline during resuscitation in the dopexamine group, and liver tissue oxygen tension was significantly higher than in the control group. After 60 mins of resuscitation, the liver oxygen tension decreased to control group values. None of the other tissue oxygen tensions showed any differences between groups.ConclusionsDopexamine administration during crystalloid resuscitation from hemorrhagic shock was well tolerated and resulted in significant and specific, although transient, improvement in liver oxygenation. (Crit Care Med 1997; 25:663-668)

ISSN:0090-3493    

出版商:OVID    

年代:1997

数据来源: OVID

摘要:

ObjectivesCardiac depression is the main adverse effect of severe tricyclic antidepressant poisoning. The aim of this study was to investigate whether treatment with epinephrine or norepinephrine increases survival as compared with standard treatment with sodium bicarbonate in experimental amitriptyline poisoning.DesignNonrandomized, controlled intervention trial.SettingUniversity laboratory.SubjectsMale, anesthetized, paralyzed, and mechanically ventilated Sprague-Dawley rats (n = 91).InterventionsRats subjected to a 60-min infusion of amitriptyline (2 mg/kg/min) were treated with a continuous infusion of either epinephrine, norepinephrine, sodium bicarbonate, epinephrine plus sodium bicarbonate, norepinephrine plus sodium bicarbonate, or placebo.Measurements and Main ResultsInotropic drug treatment was associated with an increased survival rate as compared with treatment with sodium bicarbonate and treatment with placebo. Epinephrine treatment was superior to norepinephrine. Additional treatment with sodium bicarbonate increased survival rate for each inotropic drug. Sodium bicarbonate and inotropic drug treatment independently increased the survival rate (p < .001 for both effects). No interaction between these two treatment effects was observed.ConclusionsBoth epinephrine and norepinephrine increased the survival rate in tricyclic antidepressant poisoning in rats. Sodium bicarbonate increased the survival rate independent of inotropic drug treatment. Furthermore, epinephrine was superior to norepinephrine when used both with and without sodium bicarbonate, and the most effective treatment was epinephrine plus sodium bicarbonate. (Crit Care Med 1997; 25:669-674)

ISSN:0090-3493    

出版商:OVID    

年代:1997

数据来源: OVID

摘要:

ObjectiveTo determine the validity and clinical utility of the partial CO sub 2 rebreathing technique for measurement of nonshunted pulmonary capillary blood flow and cardiac output.DesignProspective, controlled animal laboratory investigation and clinical trial.SettingsAnimal research facility and intensive care unit of a university hospital.SubjectsFifteen adult sheep, weighing 58 to 78 kg.PatientsMechanically ventilated patients with different underlying diseases (n = 12) and with adult respiratory distress syndrome (ARDS) (n = 8).InterventionsCO2elimination rate (VCO2) was measured breath-by-breath with a system developed for the study and also by gas collection (validation procedure in patients with different underlying diseases). Partial CO2rebreathing maneuvers, cardiac output by thermodilution, and blood gas analysis were performed in sheep with lung atelectasis and in patients with ARDS.Measurements and Main ResultsThe degree of correlation between VCO2measured with the system developed and gas collection was very good (r2= .95, p < .0001), and bias and precision calculations (1 +/- 9 mL/min) showed close agreement between methods. The overall degree of correlation between partial CO2rebreathing measurements and cardiac output was moderate (r2= .54, p < .0001), the noninvasive method tending to underestimate cardiac output, as shown by bias and precision calculations (-1.69 +/- 1.90 L/min). In contrast, the overall degree of correlation between partial CO2rebreathing measurements and nonshunted pulmonary capillary blood flow was good (r2= .73, p < .0001). Bias and precision calculations (0.25 +/- 0.83 L/min) showed a tendency for the partial CO2rebreathing technique to slightly overestimate pulmonary capillary blood flow. Variance differences between partial CO2rebreathing measurements and cardiac output could be mostly explained by intrapulmonary right-to-left shunt fraction (r2= .51, p < .0001).ConclusionsOur results support the use of the system developed for breath-by-breath VCO2measurements. The lack of agreement between partial CO2rebreathing measurements and cardiac output was mostly explained by intrapulmonary right-to-left shunt, suggesting that this technique may not be appropriate for monitoring cardiac output in patients with increased venous admixture. In contrast, our results demonstrate that the partial CO2rebreathing technique is reliable for measurement of the effective nonshunted pulmonary capillary blood flow. This technique may prove useful to guide ventilatory therapy adjustments in an attempt to optimize nonshunted pulmonary capillary blood flow. (Crit Care Med 1997; 25:675-683)

ISSN:0090-3493    

出版商:OVID    

年代:1997

数据来源: OVID