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Biomedical subjects

N Valentin

Publications and source records attributed to N Valentin.

At least 55 records · Page 3Linked to original sources
PubMed1982

Arterial to end-tidal carbon dioxide tension difference in children under halothane anaesthesia.

Using blood gas determinations and capnography, the relationship between arterial and end-tidal PCO2 was investigated in 20 children under halothane anaesthesia with spontaneous respiration. A median arterial to end-tidal carbon dioxide tension difference of 0.66 kPa (5 mm Hg) was found. There was a close correlation between PaCO2 and the magnitude of the carbon dioxide difference. Our findings may largely be explained by an increase in VD/VT (presumably mainly due to a reduction of VT) causing admixture of dead space air throughout expiration. It is concluded that though end-tidal carbon dioxide does not exactly reflect PaCO2 capnography may be of value as a monitor of respiration in paediatric anaesthesia at normal or near-normal values of end-tidal carbon dioxide.

Adenoidectomy↗
PubMed1982

Halothane anaesthesia with spontaneous respiration for tonsillectomy in children.

Bains's anaesthetic circuit was used in 22 children undergoing tonsillectomy under halothane anaesthesia with spontaneous respiration. End-tidal CO2 was monitored by capnography. The median maximum end-tidal CO2 was 7%, and during surgery nine patients had an end-tidal CO2 higher than 7%, corresponding to a Paco2 close to 8 kPa when the arterial to end-tidal CO2 difference is taken into consideration. Increase in fresh gas flow or change to a non-rebreathing system had virtually no effect on end-tidal CO2. However, following discontinuation of halothane or during controlled respiration, acceptable values of end-tidal CO2 were reached, leading to the conclusion that respiratory depression was responsible for the high values of end-tidal CO2 rather than properties of Bain's circuit or too low gas flow rates.

Anesthesia, General↗
PubMed1982

Routine induction of anaesthesia with thiopental and suxamethonium: apnoea without ventilation?

Changes in Paco2 and Paco2 during the induction of anaesthesia with thiopental suxamethonium, and intubation were investigated in 20 patients who received preoxygenation for 2 min, but no ventilation before intubation. Both in fit patients below the age of 60 years (Group I) and in patients above the age-several suffering from cardiopulmonary disease - (group II), Pao2 increased to about 40 kPa during preoxygenation and remained at the level during apnoea. Mean Paco2 increased to 6.3 and 5.7 kPa in Groups I and II, respectively. No complications were seen, and it is concluded that the apnoea involved in the "crash induction" technique is sage. Pulmonary aspiration of acid gastric fluid may also occur in fasting patients, and it is suggested that even in elective cases ventilation might advantageously be replaced by preoxygenation when anaesthesia is induced with thiopental and suxamethonium.

Anesthesia, General↗
PubMed1982

Atropine before enflurane anaesthesia: effects on cardiac rhythm, pulse rate, blood pressure and airway secretion.

The occurrence of cardiac arrhythmias and changes in pulse rate and blood pressure during mask anaesthesia with enflurane was investigated in 92 patients with special reference to the influence of atropine (0.01 mg kg-1 5 min before anaesthesia) and thiopental. The average duration of anaesthesia was a little less than 1 h in all four groups. More than five ventricular extrasystoles occurred in one patient (38 min after atropine). Supraventricular (mainly nodal) arrhythmias were significantly (P less than 0.005) more common in the atropine groups (15/45) than in the non-atropine groups (4/47). Following atropine, heart rate increased by about 25 beats min-1, whereas only very slight increases were seen in the non-atropine groups. Blood pressure fell at the induction but was almost back to normal at the end of anaesthesia. Blood pressure was unaffected by atropine. Slightly lower values of blood pressure were suggested in the thiopental groups, whereas thiopental did not modify cardiac rhythm or pulse rate. Suction of the pharynx was necessary in only one patient. In conclusion, the present study does not support the routine administration of atropine before enflurane anaesthesia with or without thiopental induction.

Adolescent↗
PubMed1981

Preanaesthetic medication with rectal diazepam in children.

With the purpose of avoiding injections to children, the quality of rectal premedication with a solution of diazepam (Apozepam) was investigated in a double-blind study. Compared with a lytic cocktail (containing pethidine, promethazine and chlorpromazine), adequate preanaesthetic sedation was obtained with rectally administered diazepam in a dose of 0.75 mg kg-1. However, following rectal diazepam, the majority of the children were very restless during recovery, but the combination of diazepam premedications and a small dose of lytic cocktail given i.m. during anaesthesia secured a smooth recovery in practically all children. The proportion of cases classified as "unsatisfactory' was higher in children below the age of 5 years than in the older children.

Child↗
PubMed1976

Myocardial uptake of digoxin in chronically digitalized dogs.

1 The time course of myocardial uptake of digoxin, increase in contractility and changes in myocardial potassium concentration was studied for 90 min following an intravenous digoxin dose to long-term digitalized dogs. 2 Nineteen dogs were investigated by the use of a biopsy technique which allowed sampling before and after administration of digoxin. 3 Ten minutes after administration of digoxin the myocardial concentration increased from 60 to 306 nmol/kg tissue, the myocardial concentration of digoxin was significantly lower (250 nmol/kg tissue) after 30 min and then increased again. 4 The transmural myocardial distribution of digoxin was uniform before and 90 min after administration of digoxin in long-term digitalized dogs but at 10 min after administration, both the subepicardial and the subendocardial concentration of digoxin were significantly lower than that of the mesocardial layer. 5 During the first 10 min the dp/dtmax increased to 135% of the control level. The increase remained unchanged during the rest of the study. 6 Myocardial potassium decreased throughout the study. 7 The M-configuration of the myocardial uptake curve and the non-uniformity of myocardial distribution of digoxin observed at 10 min after administrating digoxin to long-term digitalized dogs indicate that the distribution of myocardial blood flow may be changed during chronic digitalization.

Animals↗
PubMed1976

Myocardial digoxin uptake: dissociation between digitalis-induced inotropism and myocardial loss of potassium.

The time course of myocardial uptake of digoxin, of increase in inotropic effect and of changes in myocardial potassium content were studied following a single intravenous dose of digoxin. Nineteen dogs with intact circulation were investigated by the use of a biopsy technique which allowed samplings before and 10, 30, 60, and 90 min after administration of digoxin. The myocardial concentration of digoxin was 196 X 10(-9) mol/kg 10 min after administration of digoxin. Uptake continued at a slower rate, maximum concentration being 293 X 10(-9) mol/kg at 60 minutes. The inotropic effect increased parallel with the uptake of digoxin; 10 min after digoxin, contractility was 127% of the control value and this increased to 139% at 90 minutes. Myocardial potassium content was slightly increased 10 min after digoxin, suggesting an initial stimulation of membrane Na+-K+ ATPase. A subsequent significant fall in the myocardial potassium content probably reflects ATPase inhibition. The temporal dissociation between the early onset of the positive inotropic effect and the delayed inhibition of membrane Na+-K+ ATPase indicates that inotropism of digitalis glycosides is not mediated by the same binding site as that responsible for inhibition of Na+-K+ ATPase.

Animals↗
PubMed1976

Effects of ouabain and hypoxia on the cardiac stimulation threshold in the dog (with special reference to changes in extra- and intracellular potassium concentrations).

The influence on the cardiac stimulation threshold of changes in the myocardial intra/extracellular potassium ratio induced with ouabain and hypoxia was investigated in 9 dogs with total atrioventricular block. In spite of significant elevations of extracellular potassium and reductions of intracellular potassium significant changes in stimulation threshold were not seen. It is suggested that different experimental conditions are responsible for the great variations in the results of previous studies of this subject.

Action Potentials↗
PubMed1975

Muscle cell electrolytes in ulcerative colitis and Crohn's disease.

The intracellular electrolyte concentrations in skeletal muscle from 15 patients with ulcerative colitis or Crohn's disease were examined. In patients with diarrhea not receiving potassium, muscle cell potassium and magnesium were low and sodium insignificantly elevated. By contrast, largely normal muscle cell electrolyte concentrations were found in patients receiving potassium or having a normal intestinal function. Supported by the existence of normal muscle cell electrolytes in a control group of patients receiving prednisone for extraintestinal diseases it was stated that glucocorticoid treatment does not affect the muscle cell electrolytes unless such treatment is effective in controlling the intestinal function. Potassium - and possibly magnesium - supplementations are recommended in cases with diarrhea.

Adolescent↗
PubMed1975

Plasma potassium and insulin during extracorporeal circulation using a glucose-containing pump prime.

In order to investigate the possible relationship between a glucose-containing pump prime and changes in plasma potassium during extracorporeal circulation, determinations were made of blood glucose and plasma insulin, potassium, and magnesium in 18 subjects undergoing open-heart surgery. In 6 of the patients, the same parameters had been measured during a pre-operative glucose tolerance test. It was found that the elimination of glucose was considerably impaired during extracorporeal circulation, in spite of high insulin levels. During the first minutes of extracorporeal circulation, plasma potassium fell more than during the glucose tolerance test, in spite of comparable insulin levels. It is concluded that changes in plasma potassium during extracorporeal circulation do not reflect insulin activity to any noticeable extent.

Adolescent↗