Oxygen transport during extracorporeal oxygenation for the treatment of adult respiratory distress syndrome

An inventory of hemodynamic and respiratory measurements was obtained in two patients with acute respiratory failure syndrome prior to and during venoarterial extracorporeal membrane oxygenation for study of oxygen transport. As the inspired oxygen concentration fraction was reduced from 1.0 to 0.5 and paO2 was increased from less than 50 to physiologic ranges during extracorporeal membrane oxygenation, tachycardia and pulmonary hypertension were reversed. Total oxygen transport was reduced rather than increased. Oxygen consumption and oxygen extraction were not altered during extracorporeal membrane oxygenation. However, a striking reduction was observed in cardiac output. After reversal of anoxemia, the total of the cardiac output of the patient and the extracorporeal membrane oxygenation flow were less than the cardiac output of the patient prior to extracorporeal membrane oxygenation. These observations provide evidence that the beneficial effects of extracorporeal membrane oxygenation stem, at least in part, from a reduction of the work load on the heart. Since high cardiac output failure is observed during progression of adult respiratory distress syndrome, mechanical support of circulation during extracorporeal membrane oxygenation may be of primary therapeutic benefit.     

Drug-induced pneumopathies accompanied by acute respiratory insufficiency

Drug induced pneumonias accompanying acute respiratory failure are defined by a delay in presentation of less two months and severe hypoxaemia (PaO2 < 60 mmHg in ambient air). They are poorly indexed, often poorly understood by the clinician and pose difficult problems both of diagnosis and treatment. This general review touches successively on hypoxaemic drug induced pneumonia observed in oncology and haematology then those observed outside this very specific context. In each of the two groups five questions are posed: 1) Which patients? 2) Which clinical patterns? 3) What initial diagnostic discussion? 4) Which successful elements support the drug induced hypothesis? 5) What outcome? The replies obtained were compared to case reports from the literature (188 references) or from recent general reviews concerned more specifically with the hypoxaemic forms.     

The role of the extracorporeal detoxication in prophylaxis and treatment of respiratory disorders in patients with acute ileus

Hemosorption (HS) and plasmapheresis (PA) stimulate significantly the pulmonary metabolic functions due to their potent detoxicational effect. Arterial hypoxemia occurs simultaneously. The PA application contra HS causes more durable and stable detoxicational effect. It is mandatory in patients with an acute ileus to combine the HS conduction and repeated sessions of spontaneous respiration with end-expiratory additional pressure and to include fatty emulsions in complex of substitutional therapy while PA application.     

Cardiac oxygenation by extracorporeal membrane oxygenation in exteriorized fetal lambs

Inhibitors of 3-hydroxy-3-methylglutaryl (HMG)-CoA reductase, such as Simvastatin and Lovastatin, reduce the rate of DNA synthesis and proliferation of a wide variety of cell types in vitro, by inducing a cell cycle arrest in G1. In estrogen-free medium, DNA synthesis is reduced by more that 90% following exposure of normal and transformed human breast epithelia] cells to 20 microM Simvastatin or Lovastatin for 24 to 42 hrs. We show here that stimulation of estrogen responsive MCF-7 cells with nanomolar concentrations of 17beta-estradiol (E2) prevents inhibition of DNA synthesis by these compounds. The effect of the hormone is antagonized by both steroidal and non steroidal antiestrogens, and it is not detectable in estrogen receptor-negative MCF-10a cells. Cell cycle analysis demonstrates that HMG-CoA reductase inhibitors are unable to induce G1 arrest of MCF-7 cells in the presence of E2.     

Mechanisms of acute respiratory insufficiency in patients with hyperglycemic coma

Basic parameters of pulmonary gas exchange, central and pulmonary hemodynamics, and colloid osmotic pressure were investigated in 31 patients in diabetic hyperglycemic coma over the course of intensive care. Pulmonary gas exchange disorders were observed in all patients in the presence of increased shunting of the blood in the lungs and disorders of transcapillary liquid exchange. On the other hand, we failed to obtain data indicative of an increase in the volume of extravascular water in the lungs. However, it does not rule out the possibility of iatrogenic disorders of gas exchange during noncontrolled rehydration.     

Bronchial lobar obstruction from a sucralfate tablet: a rare cause of acute respiratory insufficiency]

In 1995, the Committee on Sports Medicine and Fitness of the American Academy of Pediatrics (AAP) published a position paper on atlantoaxial instability in children with Down syndrome in which a previous statement on the same subject published in 1984 (Table) was retired. The 1995 statement includes several arguments that disfavor screening of children with Down syndrome for atlantoaxial instability. Whereas some of these arguments are well founded, other lack substantive evidence that would support the statement. In the following discussion, I attempt to analyze some of these arguments made in the 1995 statement and provide a viewpoint that favors radiologic examinations of the cervical spine of children with Down syndrome.     

Hemodynamic changes in acute respiratory insufficiency: the role of the right ventricle

Acute respiratory failure, particularly if associated with sepsis, results in diffuse changes in pulmonary vascular geometry and the afterload characteristics against which the right ventricle must perform. Therapy in these patients frequently requires replacement of intravascular volume which, if pulmonary vascular resistance is abnormally elevated, may cause a substantial enlargement in right ventricular (RV) end-diastolic volume. The low compliance characteristics of the RV invalidate the use of filling pressure (CVP) as a guide to RV size. We have examined RV volume in critically ill patients by means of the gated 99TAc scan and noted a substantial increase in RV volume despite filling pressure in the upper normal range. This enlargement appears to encroach upon LV function because the ejection fraction of the LV remained high despite elevation of pulmonary capillary wedge pressure (PCWP). Older patients with "silent" right coronary artery disease may become hemodynamically limited during therapy for acute respiratory failure and sepsis due to RV enlargement, increased wall tension and RV ischemia, a condition not readily diagnosed at the bedside with the usual monitoring techniques.     

Prolonged extracorporeal membrane oxygenation in the treatment of burns-induced shock lung (authors transl)

A case of third-degree burns involving 35 per cent of the body surface is reported with occurred in a 28-year-old man. On the 6th day progressive pulmonary insufficiency developed which 3 days later necessitated extracorporeal membrane oxygenation. Oxygen diffusion capacity gradually improved and the patients resumed spontaneous respiration with oxygen enriched air. He died 5 days after membrane oxygenation was discontinued due to massive haemorrhages from an infection at the site of the femoral by-pass. The technique adopted for the perfusion, which lasted 83 hours, is described.     

Cost of extracorporeal life support in pediatric patients with acute respiratory failure

OBJECTIVES: To determine the impact of extracorporeal life support (ECLS) on mortality in pediatric patients with acute hypoxemic respiratory failure (AHRF) at our institution; and to calculate the hospital charges associated with the use of ECLS. DESIGN: Retrospective review of medical records and hospital charges. SETTING: Pediatric intensive care unit (ICU) of a university-affiliated children's hospital. PATIENTS: Twenty patients admitted to the pediatric ICU between 1991 and 1995 for AHRF who received ECLS as a part of their hospital course. INTERVENTIONS: Predicted mortality was calculated using the Pediatric Respiratory Failure score and was compared with survival at the time of hospital discharge. Hospital charges were used as a proxy for resource utilization. Cost-per-life-year-saved calculations were performed based on a normal life expectancy for survivors. MEASUREMENTS AND MAIN RESULTS: Twenty patients were identified. The median age was 4.83 yrs. The median duration of ECLS was 9 days, with 19.5 days in the pediatric ICU and 23.5 days for the entire hospital length of stay. The observed mortality rate for these patients was 20%. Median predicted mortality rate based on the Pediatric Respiratory Failure score calculation was 83%. The hospital charges incurred by these patients was a median of $199,096. Based on a normal life expectancy for survivors, this results in a cost of $4,190/life-year. CONCLUSIONS: ECLS for the pediatric patient with AHRF is done at a considerable cost. However, ECLS affects survival favorably, and compares favorably when considering cost/life-year calculations. The data presented in this study may serve as a benchmark for comparison with newer therapies (i.e., liquid ventilation, nitric oxide). These data also provide a framework for cost-based analyses at other ECLS institutions.     

Dramatic effect on oxygenation in patients with severe acute lung insufficiency treated in the prone position

OBJECTIVE: To confirm the positive effect of prone positioning on oxygenation in patients with acute lung insufficiency. DESIGN: Clinical follow-up study. SETTING: The intensive care unit at a tertiary care academic hospital. PATIENTS: Thirteen patients suffering from severe acute lung insufficiency caused by trauma, septicemia, aspiration, and burn injury. Eleven of the patients had severe hypoxia (oxygenation indices [PaO2/FIO2] < or = 80 torr [< or = 10.7 kPa]). Patients > 70 yrs of age were excluded from the study. INTERVENTIONS: Treatment in the prone position without changing other ventilatory settings than FIO2 when saturation increased. MEASUREMENTS AND MAIN RESULTS: Twelve of the 13 patients responded to treatment in the prone position. The patient that did not respond improved her gas exchange when nitric oxide was instituted. She died, however, from a Gram-negative septicemia. No patient needed extracorporeal membrane oxygenation. Apart from the settings of FIO2 when saturation increased, the ventilatory settings were unchanged. In the prone position, the oxygenation index increased (p < .0002) and the alveolar-arterial oxygen gradient, P(A-a)O2, decreased dramatically (p < .0001). CONCLUSIONS: The prone position significantly improves impaired gas exchange due to severe acute lung insufficiency. It is suggested that this treatment is used before more complex modalities.     

Usefulness of extracorporeal membrane oxygenation for treatment of fulminant myocarditis and circulatory collapse

Prognosis for fulminant myocarditis with cardiogenic shock refractory to conventional therapy is poor. This report describes mechanical circulatory support with extracorporeal membrane oxygenation as an effective alternative for treating fulminant myocarditis with circulatory collapse.     

Effect of artificial ventilation on pulmonary capillary pressure in acute respiratory insufficiency

To determine the influence of intermittent positive pressure breathing (IPPB), the level of pulmonary capillary wedge pressure (PCWP) was compared during IPPB and after a short period off the respirator in 68 occasions on 42 patients with an acute respiratory failure (ARF) of various etiologies. During IPPB, the average PCWP was in the normal range in patients with toxic or neurologic comas and in cases of increased pulmonary capillary permeability edema (IPCPE), PCWP slightly increased within chronic obstructive pulmonary disease (COPD) complicated with ARF and in hemodynamic acute pulmonary edema (HAPE). During the weaning stage, PCWP decreased in the groups of coma, COPD, and IPCPE, but increased in HAPE. The weaning test demonstrates that IPPB influenced PCWP in all patients. Therefore, PCWP cannot be assumed to represent the left ventricle filling pressure. The weaning test allows differentiation of IPCPE from HAPE. In the event of over-infusion or hypovolemia, PCWP measured under IPPB can lead to misinterpretation if not followed up by a second measurement off the respirator.     

Improved oxygenation utilizing a prone positioner in patients with acute respiratory distress syndrome

OBJECTIVES: (a) To determine whether placing patients with acute respiratory distress syndrome in the prone position by a light-weight portable support frame improves oxygenation, (b) whether one can determine which patients benefit from prone positioning, and (c) to determine an effective technique for prone positioning of patients. DESIGN: Prospective, controlled trial without blinding. SETTING: Medical intensive care units in two urban university-affiliated hospitals. PATIENTS: Fifteen patients meeting a standard definition for acute respiratory distress syndrome were studied prospectively. Each patient acted as his own control for purposes of comparison. INTERVENTION: Patients were assigned randomly to begin in either supine or prone positions. The positioning frame was used to turn patients from one position to the other, and oxygenation, ventilation, respiratory mechanics, and hemodynamics were measured. RESULTS: Significantly better oxygenation was seen in the prone positions than in the supine (P < 0.05). In the overall population there was a decrease in AaDO2 of 21 mmHg when the patients were placed prone. The groups were then divided into responders (n = 9) and nonresponders (n = 6). There were significant differences between the groups (but not between positions) regarding PaO2, baseline, PaCO2, pulmonary artery pressures, and peak inspiratory pressures on the ventilator and in ICU length of stay and time on mechanical ventilatory support. CONCLUSION: Prone positioning improves oxygenation in the majority of patients studied and can be achieved relatively easily.