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Query: UMLS:C0020440 (hypercapnia)
 7,939 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effects on hemoglobin oxygen transport of acute respiratory acidosis have been studied in dogs inhaling a gaseous mixture with 12% CO2 (O2 21%) for two to five hours. In a first series of experiments, it was shown that the shape of the oxyhemoglobin dissociation curve (ODC) was not modified by severe acidosis (pH congruent to 7) lasting for two and a half hours. The Hill number (N equals 2.6) did not change significantly. The aim of the second experimental series was to stuey the Bohr effect and the hemoglobin oxygen affinity (P50). The control value for the respiratory Bohr coefficient (B) was --0.54; neither after two hours (--0.52), nor after five hours of hypercapnia (--0.55) was it significantly modified. The P50 expressed at arterial pH was much increased in acidosis (congruent to 45 torr); when expressed at standard p/ 7.4, it was slightly but significantly decreased (congruent to 1 torr) at the fifth hour. At the same time there was a decrease (p smaller than 0.05) in the erythrocyte 2,3-DPG approaching 15 p. cent; on the other hand the ATP concentration did not change significantly. No significant individual correlation was found between P50(7.4), 2,3-DPG and mean hemoglobin corpuscular concentration. These results suggest that during severe respiratory acidosis neither a change in the shape of ODC, nor a change in Bohr effect do affect the hemoglobin oxygen transport. The main characteristic remains the decrease in oxygen affinity of hemoglobin, due to the erythrocyte [H+] increase induced by hypercapnia ; this phenomenon is observed as long as the 2,3-DPG decrease stays moderate.
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PMID:[Hemoglobin oxygen transport during experimental acute hypercapnia (author's transl)]. 23 80

Twelve patients with severe chronic obstructive lung disease undergoing 15 operations were assessed with preoperative lung function tests and blood gas estimations. Their operative and postoperative course was followed. There were no deaths or serious complications. Patients fell into three groups: those with low respiratory capacity but normal blood gases, who required no special respiratory treatment apart from physiotherapy and antibiotics; those with hypoxaemia but normal arterial carbon dioxide pressure, who needed more prolonged oxygen treatment after operation; and those with hypoxaemia and hypercapnia, who needed postoperative ventilatory support. While forced expiratory volume in one second (FEV) is a good screening test in preoperative assessment it should be supplemented by arterial blood gas estimations in patients with an FEV of less than 1 litre.
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PMID:Criteria of fitness for anaesthesia in patients with chronic obstructive lung disease. 24 Apr 80

Rats were exposed 24 hours a day to carbon dioxide, 8 +/- 1%, during 2 and 4 weeks under normoxic conditions (21% oxygen). On the last day, blood was taken from the abdominal aorta under anesthesia. Leukocyte and erythrocyte counts, hemoglobin concentration, and mean cell volume were electronically measured. Hematocit and Wintrobe indexes were calculated. Leukocyte differential counts and peroxidase activity were determined on blood smears. After 4 weeks of hypercapnia, a slight decrease of neutrophilic granulocytes was observed. In mature polymorphs, peroxidase activity (cytochemically demonstrated) simultaneously decreased. Erythrocyte counts and mean cell volume remained unchanged. The most important hematological disturbance was an hemoglobin concentration drop. Consequently, it was concluded that an hypochromic anemia characterized the permanent normoxic hypercapnia in rats.
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PMID:Blood effects of permanent normoxic hypercapnia in conventional rats. 28 61

1. Patients should be divided preoperatively into low- or high-risk categories, depending on their probability of developing postoperative pulmonary complications. The evaluation should include spirometry as well as an assessment of the previously defined risk factors. 2. Patients in a low-risk category need only instruction in deep breathing pre- and postoperatively. Routine use of supplemented oxygen postoperatively is reasonable until it can be demonstrated whether such is necessary. 3. High-risk patients should be as free as possible of respiratory secretions at the time of surgery. A regimen for this purpose includes cessation of smoking, and administration of inhaled bronchodilators followed by chest percussion and postural drainage. 4. High-risk patients should be carefully instructed in deep breathing and coughing preoperatively. A mechanical device such as an incentive spirometer may be beneficial in this regard. If it is not possible to achieve spontaneous deep breathing, an attempt to accomplish this by IPPB may be undertaken. The tidal volume desired should be ordered. If IPPB does not result in large tidal volumes, it should be discontinued. 5. The deep breathing procedure found to be most successful preoperativelly should be continued postoperatively. 6. The patient should be as mobile as possible while in bed and ambulated as soon as is feasible. 7. Patients with preoperative expiratory flows of less than 20% of predicted values or with chronic hypercapnia should be carefully observed for postoperative ventilatory failure.
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PMID:Pulmonary complications of general surgery. 32 60

In 19 cases of severe chronic respiratory insufficiency by obstruction, the authors studied the haemogasometry and haemodynamic incidence of inhaling a mixture with FiO2 by various ways and in respiratory reeducation. Controled ventilation with or without manual abdominal pressure, instrumental kinesitherapy under pressure relaxor and simple oxygen inhalation. The pressure relaxor seems particularly suited to patients suffering above all from hypercapnia and obstruction because of its limited haemodynamic repercussions.
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PMID:[Variations in gas exchange and hemodynamic effects of various means of oxygen administration (spontaneous ventilation, controlled ventilation and under I.P.P.B.) in 19 severely obstructed pulmonary hypertension patients]. 32 60

Fourteen patients with acute exacerbations of chronic bronchitis and hypercapnia received two treatment periods with Intermittent Positive Pressure Breathing, the ventilator being driven by gas containing about 24% or about 45% oxygen. Arterial PO2 and PCO2 were measured before, during and after each treatment. The results demonstrated that increasing hypercapnia did not, as a rule, occur when 45% oxygen was used as the driving gas. When hypercapnia did occur it appeared to be independent of the inspired oxygen concentration. The importance of short treatment periods, correct ventilator settings and supervision of the patient during and after treatment is emphasised.
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PMID:IPPB and hypercapnia in respiratory failure: the effect of different concentrations of inspired oxygen on arterial blood gas tensions. 37 21

Two uses of intermittent positive pressure can be distinguished: one supports inhalotherapy and the other longterm assisted ventilation. The apparatus can be connected to the patient either through mouth-piece or by tracheostomy. The main factors involved in the indication of assisted ventilation are the number of acute failures, hypoxemia, hypercapnia, cor pulmonale. In our department, 53 patients were kept under prolonged supervision before a decision was made to use assisted ventilation or not. This attitude seems absolutely necessary. An oxygen test of several hours provides very useful information. Finally, the authors review the indication of various ventilation methods (tracheostomy, oral) in relation to different chronic respiratory insufficiency etiologies (ie., chronic obstructive broncho-pneumonia, restrictive syndrome).
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PMID:[Preliminary report and indications of assisted ventilation at home (author's transl)]. 39 49

A survey has been conducted among French chest physicians and physicians involved in intensive care. 296 physicians have prescribed IPPB at home to 3 778 patients with chronic respiratory insufficiency between 1960 and 1977. Acute respiratory failure was the first criteria considered in the indications (57% of the patients); hypercapnia, hypoxemia and right heart failure episode frequency were the other criteria of severity the most often taken into account. Since 1960, the indications among those with airflow obstruction have decreased, whereas they have increased for those with restrictive insufficiencies, expressing the questions raised about the efficacy of IPPB in these two types. 18% of the patients have had IPPB through tracheostomy canula. 70% of the patients have used a pressure cycling respirator and 30% a volume or flow cycling respiratory. This second type was quite always used in the case of IPPB through canula. Oxygen was added for half of the patients. The physicians have regularly followed the patients. Great importance was accorded to home care surveillance.
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PMID:[IPPB therapy at home in chronic respiratory insufficiency in France. II. Indications. Technics and surveillance (author's transl)]. 39 55

Most of the previous literature concerning otologic problems in compressed gas environments has emphasized middle ear barotrauma. With recent increases in commercial, military, and sport diving to deeper depths, inner ear disturbances during these exposures have been noted more frequently. Studies of inner ear physiology and pathology during diving indicate that the causes and treatment of these problems differ depending upon the phase and type of diving. Humans exposed to simulated depths of up to 305 meters without barotrauma or decompression sickness develop transient, conductive hearing losses with no audiometric evidence of cochlear dysfunction. Transient vertigo and nystagmus during diving have been noted with caloric stimulation, resulting from the unequal entry of cold water into the external auditory canals, and with asymmetric middle ear pressure equilibration during ascent and descent (alternobaric vertigo). Equilibrium disturbances noted with nitrogen narcosis, oxygen toxicity, hypercarbia, or hypoxia appear primarily related to the effects of these conditions upon the central nervous system and not to specific vestibular end-organ dysfunction. Compression of humans in helium-oxygen at depths greater than 152.4 meters results in transient symptoms of tremor, dizziness, and nausea plus decrements in postural equilibrium and psychomotor performance, the high pressure nervous syndrome. Vestibular function studies during these conditions indicate that these problems are due to central dysfunction and not to vestibular end-organ dysfunction. Persistent inner ear injuries have been noted during several phases of diving: 1) Such injuries during compression (inner ear barotrauma) have been related to round window ruptures occurring with straining, or a Valsalva's maneuver during inadequate middle ear pressure equilibration. Divers who develop cochlear and/or vestibular symptoms during shallow diving in which decompression sickness is unlikely or during compression in deeper diving, should be placed on bed rest with head elevation and avoidance of maneuvers which result in increased cerebrospinal fluid and intralabyrinthine pressure. With no improvement in symptoms after 48 hours, exploratory tympanotomy and repair of a possible labyrinthine window fistula should be considered. Recompression therapy is contraindicated in these cases...
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PMID:Diving injuries to the inner ear. 40 82

The effects of stimulation and blockade of dopaminergic receptors on cerebral blood flow and metabolism were investigated in 15 anesthetized baboons. The intravenous administration of apomorphine resulted in immediate, dose-dependent increases in cerebral blood flow (increased by 58% following 0.1 mg/kg apomorphine) which were always accompanied by increases in cerebral oxygen consumption (increased by 36% with 0.1 mg/kg) and glucose uptake (increased by 72% with 0.1 mg/kg). It is suggested that the primary action of apomorphine is on cerebral metabolism and secondarily on cerebral blood flow rather than directly on cerebral vascular smooth muscle. Pimozide, at doses that totally blocked apomorphine-induced increases, was without effect on cerebral blood flow and metabolism. The dilatatory response of the cerebral circulation to hypercapnia was preserved during dopamine-receptor blockade. The basal level of overall cerebral metabolism and hemispheric cerebral blood flow does not appear to be dependent to any large extent on the activity of the dopaminergic pathways in the central nervous system.
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PMID:Cerebral circulation: effect of stimulation and blockade of dopamine receptors. 40 6


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