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Biomedical subjects

S Lindahl

Publications and source records attributed to S Lindahl.

At least 55 records · Page 3Linked to original sources
PubMed1983

Cardiac arrhythmias in intubated children during adenoidectomy. A comparison between enflurane and halothane anaesthesia.

In 75 children undergoing adenoidectomy, occurrence of cardiac arrhythmias and influence of anaesthesia on respiration were studied during halothane and enflurane anaesthesia. All the children were intubated orally. In 25 children halothane, and in another 25 children enflurane was used during spontaneous ventilation. Twenty-five children were also followed during halothane anaesthesia with manually controlled ventilation. The overall incidence of cardiac arrhythmias was higher during halothane anaesthesia (72% at spontaneous breathing and 68% with controlled ventilation) than during enflurane anaesthesia (32%, P less than 0.05). Ventricular arrhythmias were noted in 20% of the spontaneously breathing children in 12% of those with controlled ventilation during halothane anaesthesia. Three children breathing spontaneously during halothane anaesthesia developed ventricular tachycardia. During enflurane anaesthesia the incidence of ventricular arrhythmias was lower (8%) in spite of higher end-tidal CO2 tensions and an anaesthetic depth that was only just the level needed to allow intubation. The incidence of ventricular arrhythmia during halothane anaesthesia was shown to be influenced by the anaesthetic technique used, which was not found with enflurane anaesthesia. The greater stability in cardiac rhythm with enflurane indicates a more favourable effect of this agent on the myocardium as well as a decreased sympathetic response to anaesthesia and surgery as compared with halothane anaesthesia.

Adenoidectomy↗
PubMed1983

Computed tomography of bone fragments in the spinal canal. An experimental study.

The detectability of bone fragments of differing size and structure, placed epidurally in the spinal canal at different levels from T XI to L II, was studied in three vertebral preparations using three different CT scanners, Philips Tomoscan 310, General Electric 8800 and Siemens Somatom 2. The thickness of the bone fragment was the most decisive factor. Cortical bone fragments could be detected down to a thickness of 0.6 mm and spongy bone fragments down to 1.2 mm. No difference in detectability between the different CT scanners was found.

Diagnosis, Differential↗
PubMed1982

Absorption and bioavailability of rectally administered morphine in women.

21 healthy women undergoing gynaecological operations received rectal premedication with morphine 0.3 mg/kg body weight. Plasma concentrations of morphine were followed for 4 h by a GC/MS technique. In most patients the peak plasma concentration was reached after 30 min; the mean peak plasma level of morphine was 18 ng/ml (range 8.5-57 ng/ml). The bioavailability of rectal morphine was determined in 6 patients, who received an i.m. injection of morphine at a second operation. The mean bioavailability of rectal morphine was 31% (range 12%-61%). None of the patients showed any clinical sign of respiratory depression, and there was no increase in end-tidal carbon dioxide tension measured in 5 patients operated under spinal block.

Adult↗
PubMed1982

Influence of premedication on plasma ACTH and cortisol concentrations in children during adenoidectomy.

The endocrine response to stress, as reflected by the plasma concentrations of ACTH and cortisol, was investigated in 14 children receiving two different premedications during halothane anaesthesia for adenoidectomy. Seven children (group A) were premedicated with diazepam 5 mg rectally and atropine 0.3-0.4 mg sublingually and seven (group B) received a rectal combination of diazepam 0.5 mg kg-1, morphine 0.15 mg kg-1 and hyoscine 0.01 mg kg-1. Before and after surgery plasma concentrations of ACTH and cortisol were lower in group B than in group A. In group A mean values for ACTH increased from 40.7 ng line-1 before adenoidectomy to 352.9 ng litre-1 (P less than 0.001) after adenoidectomy. The corresponding increase in group B was from 12.1 ng litre-1 to 82.1 ng litre-1 (P less than 0.01). In group A mean cortisol concentrations increased from 235.7 nmol litre-1 to 655.7 nmol litre-1 after adenoidectomy (P less than 0.01) and in group B from 121.4 nmol litre-1 to 427.9 nmol litre-1 (P less than 0.01). End-tidal carbon dioxide tension was approximately the same in both groups. It was concluded that the combination of diazepam, morphine and hyoscine decreased the endocrine response to stress.

Adenoidectomy↗
PubMed1982

Experimental cutaneous pain thresholds and tolerance in clinical analgesia with epidural morphine.

Ten patients experiencing significant analgesia from repeated low-dose morphine injections via an indwelling epidural catheter were studied. One group (n = 5) with acute, postoperative pain was tested for changes in experimental cutaneous pain thresholds with and without clinical morphine analgesia. Three of these patients received intravenous naloxone. The analgesia was reversed in two. There was no significant alteration in any cutaneous modality, including pain, although the postoperative deep pain was relieved. This discrepancy might be explained by the existence of separate subpopulations of opiate receptors at the spinal cord level, which differentiate nociceptive input from the skin and from deep body structures. The other group (n = 5) of cancer pain patients with a permanent epidural catheter was monitored for long-term changes in clinical pain. Signs of tolerance were not seen with an observation period up to 6 weeks.

Aged↗
PubMed1981

Circulatory and ventilatory effects of hypervolaemia in artificially ventilated piglets.

The influence of hypervolaemia upon circulation and pulmonary ventilation was studied in six piglets (body weights 8.5-10.5 kg). A new functional principle for artificial ventilation was used. The alveolar ventilation was unchanged at normovolaemia and hypervolaemia. Arterial blood gases were sampled and end-tidal carbon dioxide concentrations were measured continuously. Central circulation was followed by pressure recordings and an electromagnetic flow meter for cardiac output measurements. Mean values +/- SEM of end-inspiratory tracheal pressures increased from 0.98 +/- 0.06 kPa at normovolaemia to 1.57 +/- 0.06 kPa at hypervolaemia (p less than 0.02). In all animals total compliance decreased (p less than 0.02). Simultaneously the insufflation time for the tidal volume decreased by 13 per cent (p less than 0.05). Arterial oxygen tensions decreased from 8.5 +/- 0.48 kPa to 7.0 +/- 0.77 kPa (p less than 0.05). During hypervolaemia aortic pressures increased from 13.1 +/- 1.3 kPa to 14.9 +/- 0.8 kPa (p less than 0.05), pulmonary artery pressures from 2.8 +/- 0.33 kPa to 5.0 +/- 0.53 kPa (p less than 0.02) and cardiac output from 1.07 +/- 0.17 1 . min-1 to 1.5 +/- 0.19 1 . min-1 (p less than 0.02). The stroke work for the right heart increased by 74 per cent (p less than 0.02) and for the left heart by 62 per cent (p less than 0.02). Pulmonary vascular resistance was unchanged, while systemic vascular resistance was significantly decreased (p less than 0.05). The positive effect upon systemic circulation gained by the use of excessive fluid therapy resulted in an overcirculation within the lungs which reduced pulmonary ventilation. This reduction could most probably be related to a closure of terminal airways secondary to lung hyperperfusion, increasing the pulmonary shunt.

Animals↗
PubMed1981

Carbon dioxide output in spontaneously breathing infants during anaesthesia and surgery.

Twenty-eight infants were anaesthetized with halothane, nitrous oxide and oxygen and allowed to breathe spontaneously through a non-rebreathing system during minor paediatric surgery. Carbon dioxide output was correlated negatively with body weight for infants greater than 10 kg, but not for children less than 10 kg. Carbon dioxide output was unchanged compared with before surgery.

Anesthesia, Inhalation↗
PubMed1981

Bedside calculation of body surface area for infants and children.

In 179 healthy boys and girls, the relationship between body surface area (S) in dm2 and body weight (bw) in kg was investigated. The body surface was calculated from the DuBois and DuBois formula. For infants below 20 kg, the relationship followed the regression equation S=3.6kg + 9; r=0.996. For infants with bw between 20-40 kg, the regression equation S=2.5.kg + 33; r=0.977 was found. These equations can easily be memorized and may be able to replace nomograms when bedside calculations of the S is required. In addition, formulas for the volume of plasma expander to be used in the prophylaxis and treatment of shock, trauma, and burn injuries are presented.

Body Height↗
PubMed1981

Rectal premedication in children. Use of diazepam, morphine and hyoscine.

Rectal premedication with diazepam, morphine and hyoscine has been used in 20 healthy children undergoing minor surgery. Satisfactory sedation was achieved in the majority of children and the anticholinergic effects were also adequate. Peak plasma levels of diazepam and morphine were reached within 30 minutes, and the plasma levels decreased after 2 hours. No adverse effects on ventilation were seen during anaesthesia.

Anesthesia, Inhalation↗
PubMed1980

Dynamic behaviour of the chest and of the abdomen in anaesthetized piglets during rapid insufflation.

Three piglets were ventilated with a TVM-ventilator, which releases predetermined volumes of compressed gas into the airways. The inspiratory flow depends on the pressure and volume of the compressed gas and compliance, resistance and inertia of the lungs, thorax and abdomen of the subject. The time for half filling of the chest was less than that of the abdomen and the difference increased with high driving pressure (with high acceleration). The difference was thus most probably a result of greater inertia of the abdomen. Inertia also seemed to influence the emptying of the lungs. This was so slow that increase of FRC--air trapping--was seen at a ventilatory frequency of 30 b.p.m. The practical consequences of these findings are that the abdomen (diaphragm) will take less and less part in ventilation and that a phase lag between chest and abdominal breathing should become larger with increasing ventilatory frequency. FRC will increase in regions with expiratory obstruction and lung rupture may follow.

Abdomen↗
PubMed1979

Influence of an end inspiratory pause on pulmonary ventilation, gas distribution, and lung perfusion during artificial ventilation.

Using a constant tidal volume and ventilatory frequency, anesthetized piglets were ventilated with a new tidal volume ventilator. A short inspiratory time without a pause (10% of breathing cycle) was compared with a longer inspiratory time with a pause (33%) both with and without bronchial obstruction. Mechanics of ventilation, pulmonary ventilation, gas exchange, gas distribution, and lung perfusion were measured. The longer inspiratory time with a pause resulted in lower peak airway and end inspiratory pressures and a higher total compliance. Dead space/tidal volume ratio was reduced and the RQ was increased. While the cranial pulmonary fields were less well ventilated, the right caudal field was better ventilated. In the presence of bronchial obstruction, better alveolar ventilation was achieved when an end inspiratory pause was added. The results emphasize the importance of static end inspiratory tracheal conditions although the tidal volumes were kept unchanged.

Animals↗
PubMed1979

Experimental studies on artificial ventilation using a tidal volume ventilator. Mechanics and dynamics of ventilation.

In 24 piglets (2.7-24.5 kg b.w.), the mechanics of ventilation, the accuracy of dosage of respiratory volumes, and the influence of the ventilator's volume/pressure characteristics (Cvent, "internal compliance") on the dynamic course of insufflation were studied. A linear relationship was shown to exist between tidal volume and end-inspiratory tracheal pressure and between tidal volume and insufflation time. The insufflation time was reduced to about 50% of previously registered values. The error between set and registered tidal volume was found to be 6.0 +/- 2.7%. During the insufflation a linear relationship was found between the instant amount of delivered breathing gas and the corresponding endotracheal pressure change. The ventilator's Cvent did (and body size, total compliance and tidal volume did not) significantly influence the size of the direction coefficient for the linear instantaneous volume/pressure relationship, the magnitude of tracheal peak pressure and a short insufflation time, and vice versa. The use of greater power from the ventilator resulted in a significant shortening of the duration of insufflation and vice versa. The duration of insufflation is the parameter of choice in evaluating the efficiency of the ventilatory equipment. When the ventilator's performance is defined, measurements of the duration of insufflation may enable evaluation of conditions within the lungs.

Animals↗
PubMed1979

The circulatory response to specific ventilatory patterns using a tidal volume ventilator.

The circulatory response to different ventilatory patterns during artificial ventilation was examined in 17 sternotomized piglets. A constant CO2-tension level was maintained in all investigations by reference to analyses of the end-tidal infra-red CO2 fraction and arterial CO2-tension. The greatest variation in mean values for end-tidal CO2-tension was 0.2 kPa. Total compliance and lung compliance were lower at a ventilator volume/pressure quotient of 20 compared to those at 80 ml/kPa, and at f = 30 compared to f = 11 cycles/min. Higher cardiac output, lower pulmonary vascular resistance and systemic vascular resistance were measured at f = 11 (inspiration 20%) than at f = 30 (inspiration 50%). An increase in inspiration time by about 100% at the lower ventilatory frequency (f = 11) resulted in a significant but uncompensated decrease in cardiac output and stroke volume. These results demonstrate the value of a rapid insufflation in order to give longer expiration time per minute for the benefit of the venous return and cardiac output.

Animals↗
PubMed1979

Influence of ventilatory frequencies and ventilator volume/pressure quotients on pulmonary ventilation using a tidal volume ventilator.

The influence of ventilatory frequency and the ventilator's "internal state of gas compression" (Cvent) on mechanics of ventilation, pulmonary ventilation, gas distribution, gas exchange and lung perfusion was studied with free airway and experimental regional airway obstruction in 10 piglets (7-12 kg b. w. ), using a tidal volume ventilator. The VDphy/VTexp ratio was greater at f = 30 than at f = 10.3 cycles/min. This could be related to a significant increase in the VDanat/VTexp ratio at f = 30, while VDc/VTexp and VDlav/VTexp were unchanged at both frequencies. With regional ventilation and perfusion within the obstructed pulmonary field were reduced, compared to the values at f = 10.3 cycles/min. With Cvent 20 ml/kPa, the tidal volumes were insufflated in a shorter time and with a higher initial tracheal peak pressure than with Cvent 80 ml/kPa. Following bronchial obstruction, VA, RQ and Pao2 were greater with Cvent 20 than with Cvent 80 ml/kPa. With Cvent 20, the ventilation of the lung bases was reduced, which was compensated for by a large increase in ventilation within the apical areas of the lungs, while gas distribution within the unobstructed areas was more evenly distributed with Cvent 80. Ventilation at Cvent 20 showed no essential advantage over Cvent 80. Only in lungs extremely difficult to ventilate and with ventilatory frequencies over 50 cycles/min could possible indications for Cvent 20 be seen.

Animals↗
PubMed1979

Artificial ventilation in children during anaesthesia using a tidal volume ventilator.

Standards for artificial pulmonary ventilation at ventilatory frequencies of 15 and 20 cycles per min, (PETCO2 4 +/- 0.5 kPa), were defined in 16 children with healthy lungs and body weights between 2.6 and 22.6 kg. A tidal volume ventilator and balanced anaesthesia were used during abdominal surgery. At f = 20 cycles/min an approximately direct proportionality existed between tidal volume and body weight (VTpat = 12.3 . kg b.w.--2.1, r = 0.99). The mean value VTpat per kg b.w. was 12.1 +/- 1.4 ml/kg. At f = 15 cycles/min, a linear relationship between tidal volume and kg b.w. was recorded (VTpat = 14.6 . kg b.w. + 16, r = 0.97). The mean value VTpat per kg b.w. was 15.9 +/- 1.5 ml/kg. A significant decrease in total compliance was recorded during the initial part of the surgical procedure. A rectilinear relationship existed between total compliance and kg b.w. (CTOT = 11.2 . kg b.w.--12.5, r = 0.95). The mean value CTOT per kg b.w. was 9.7 +/- 0.54 ml/kPa/kg at f = 20. The endotracheal peak pressure maintained a fairly constant pressure level independent of the initial pressure within the ventilator, the tidal volume and the body weight, a phenomenon explained by the hypothesis that the proportional increase in total lung volume and functional residual capacity in the older children compensated for the higher pressures.

Abdomen↗