LIQUID OXYGEN CONTAMINANTS—INCREASE IN CONCENTRATION DURING USE OF DOMICILIARY LIQUID OXYGEN MEDICAL SYSTEMS

The quality of liquid oxygen in domiciliary medical systems used for oxygen therapy was investigated during the emptying cycle under simulated breathing conditions. The increase in the levels of contaminants during the use of these systems was evaluated by gas chromatography and two sampling methods. The quality of liquid oxygen from storage tanks located in hospitals and in the production or in distribution plants was also investigated.     

AUDIT OF OXYGEN THERAPY

We audited the use of oxygen in our hospital. Over three days we found 119 patients using oxygen, 21 wearing their mask incorrectly or not at all. The commonest indication was chronic obstructive pulmonary disease. Forty patients had no record of arterial gas analysis. Of those who had, 29 did not require oxygen and the average time from last arterial gas analysis was 5.7 days and only eight patients were being monitored with an oximeter. Taking into account the risk of exacerbating carbon dioxide retention and the problems that arise when discharging a patient who has been receiving oxygen therapy for the duration of their admission, we feel oxygen therapy should only be administered with the knowledge of the arterial gases and with frequent reassessment during therapy.     

OXYGEN POISONING IN MAMMALS

1. Oxygen in concentrations of over 70 per cent of an atmosphere is poisonous to dogs, rabbits, guinea pigs and mice. 2. The poisonous effects manifest themselves in drowsiness, anorexia, loss of weight, increasing dyspnea, cyanosis and death from oxygen want. 3. The cause of oxygen want is a destructive lesion of the lungs. 4. The lesion may be characterized grossly as an hemorrhagic edema. Microscopically there is to be seen in varying degrees of intensity (a) capillary engorgement with hemorrhage, (b) the presence of interstitial and intraalveolar serum, (c) hypertrophy and desquamation of alveolar cells, (d) interstitial and alveolar infiltration of mononuclear cells. 5. The type of tissue reaction is not characteristic of an infectious process and no organisms have been recovered at autopsy from the heart''s blood or from lung puncture. 6. The poisonous effects of inhalations of oxygen-rich mixtures do not appear to be related to impurities in the oxygen, nor are they related to faulty ventilation, excessive moisture or increased carbon dioxide in the atmosphere of the chambers in which the experimental animals were confined.     

OXYGEN POISONING IN COLD BLOODED ANIMALS

1. Exposure of frogs to atmospheres containing approximately 95 per cent of oxygen is without apparent effect on their state of well being, and produces no noticeable changes in the appearance of their web capillaries. 2. Turtles exposed to similar atmospheres are also apparently unaffected unless the oxygen be warmed to mammalian temperature. 3. At this temperature (37.5°C.) the turtles behave like mammals, showing loss of appetite, shortness of breath, death and, at autopsy, hemorrhagic extravasations in the lungs. 4. Young turtles are more resistant (or adaptable) to this change in environment than mature ones.     

EXERCISE CAPACITY IN SUBJECTS WITH HIGH OXYGEN AFFINITY

Exercise capacity and hemodynamic parameters were measured in ten patients with a previously unpublished variant of hemoglobin (Hb-Linkbping) and in ten age- and sex-matched controls. Bicycle ergometer test was almost maximal and the indices of working capacity and cardiac tolerance were similar in patients and controls. The hemoglobin dissociation curve was shifted to the left at rest and after exercise the shift to right was half of the corresponding shift in controls. Lactate accumulation during exercise was similar in patients and controls, also the elimination rate seems identical, but requires further studies. Hydrogen ion production in the patients during exercise was more marked than in the controls. If this is a sign of altered energy metabolism remains to be ascertained in future studies. In acute short-term exercise the patients with abnormally high hemoglobin oxygen affinity seem to have similar tolerance and cardiovascular load. Aberrant metabolism and adaptation to relative hypoxia in spite of erythrocytosis may have long-term effects that require long-term follow-up of these patients.     

THE PATHOLOGICAL EFFECTS OF ATMOSPHERES RICH IN OXYGEN

In spite of numerous abnormalities or non-experimental lesions in the rabbit certain facts can be considered as established. It has been known for many years that pneumonia is produced by the more or less prolonged inhalation of high partial pressures of oxygen. The studies herein reported show that atmospheres containing 80 to 96 per cent oxygen under normal barometric pressure produce in 24 hours, or more commonly 48 hours, congestion, edema, epithelial degeneration and desquamation, fibrin formation, and finally a pneumonia, probably of irritative origin and to be described as a fibrinous bronchopneumonia. The important new points are the time relations of these changes and definition of the type of the pneumonia. Other studies have noted slight passive congestion, but it is now established that this is to be accounted for in most cases by dilatation of the right side or of both sides of the heart. This congestion affects all the abdominal viscera and is accompanied by certain secondary changes such as cloudy swelling of the parenchymatous organs and phagocytosis of erythrocytes by endothelial cells of the mesenteric lymph nodes. Although deficiency of oxygen may affect the hematopoietic system, the animals subjected to high oxygen percentages failed to show any demonstrable pathologic changes in blood, spleen, lymph nodes, or bone marrow, except for the presence of congestion. This study is the first of a comprehensive series projected in and under the direction of the Carnegie Nutrition Laboratory. Different animals and various methods of attack will be employed in the investigation.     

THE OXYGEN CONTENT OF THE BLOOD IN LOBAR PNEUMONIA

In most cases of uncomplicated lobar pneumonia the decrease of respiratory surface is completely compensated for, and the oxygen content of the blood is within normal limits. Occasional cases of uncomplicated pneumonia have an oxygen content of the venous blood which is below normal. In the two cases reported here, this was associated with a carbon dioxide content of the blood which was higher than normally, and the condition was apparently due to an interference with the respiratory exchange of gases. In the terminal stage of the fatal cases of pneumonia in which death does not occur with great suddenness, there is often a progressive diminution in the oxygen content of the blood. Synchronous with this is a progressive decrease in the oxygen-combining capacity of the blood. These changes are usually seen in patients in whom an intense bacteremia has developed and are analogous to those found in the arterial blood of infected rabbits, and to those resulting from the growth of the pneumococcus in blood in vitro. In all three conditions there is probably a change of oxyhemoglobin to methemoglobin. This change of the hemoglobin molecule, so that it no longer takes up and gives off oxygen readily, is probably a factor in the immediate cause of death in many cases of pneumonia.     

高压氧对神经病理性痛大鼠的疼痛行为学影响

目的:观察高压氧(HBO)对神经病理性痛大鼠的疼痛行为学影响及有效性.方法:40只雄性SD大鼠随机分成5组:即空白对照组(C组)、假手术组(M组)、坐骨神经慢性缩窄手术组(CCI组)、高压氧预处理组(Pre-H组)与高压氧干预组(Post-H组),对其疼痛行为学指标进行比较.结果:Pre-H组和Post-H组的机械性缩足反射阈值(MWT)较CCI组明显升高;热缩足反射潜伏期(TWL)较CCI组明显延长.HBO在热痛模型中显示的作用大子机械痛模型;Pre-H的作用大于Post-H.结论:高压氧对CCI大鼠神经病理性疼痛有一定的抑制作用.     

THE TREATMENT OF ANOXEMIA IN PNEUMONIA IN AN OXYGEN CHAMBER

1. The use of an oxygen chamber in the treatment of pneumonia patients makes it possible to administer this gas for long periods of time under exactly known conditions. The medical and nursing care of the patient is greatly facilitated. 2. Prolonged inhalation of oxygen varying from 40 to 60 per cent appears to be without harm. 3. Oxygen administered to intensely anoxemic patients almost immediately clears up this anoxemia. Cyanosis disappears with the anoxemia. 4. The removal of patients from the high oxygen while they are still sick and while examination shows that there are still extensive edema and infiltration of the lung results in a return of the intense anoxemia. 5. It is sometimes impossible to clear up the anoxemia, even when as high as 60 per cent of oxygen is given, especially when there are considerable edema and infiltration of the lungs. 6. Five cases in which the prognosis was grave recovered. Three cases, one of tuberculosis, one with a Pneumococcus Type III infection, and a third with a pneumonia superimposed on a chronic pulmonary condition, died. 7. In all cases there appeared to be an improvement in the patient''s condition. In one case, particularly, with an intense degree of anoxemia, the patient became moribund and pulseless. Following the administration of 60 per cent of oxygen there was a lowering of the heart rate from 160 to 120, the return of the pulse to the radial artery, the color became bright pink, and there was a remarkable change in the clinical condition. 8. The anoxemia of pneumonia is due, in large measure, to an impairment of the respiratory surface of the lungs. The greater the lung involvement the greater the anoxemia. Especially is this so when the pneumonic process extends throughout the lungs so that there are many patches of bronchopneumonia, with accompanying bronchitis and edema, as evidenced by the presence of râles throughout the lungs. 9. Rapid and shallow breathing of the degree observed in pneumonia is, as far as present evidence shows, of less importance in the production of anoxemia.