Upsala journal of medical sciences
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In an experimental study we determined the response trigger delay time of three infant ventilators with a capacity to detect and support spontaneous breathing. We measured this in anaesthetized cats as the time between the start of phrenic nerve activity and the increase in airway pressure caused by the subsequent inflation. Two modes of ventilatory support were used, namely Assist/Control (A/C) and synchronised intermittent mandatory ventilation (SIMV). ⋯ A higher set sensitivity reduced the response time. We conclude that triggered ventilation may be used in infants, at least when the spontaneous breathing rate is below 60 breaths per minute. This mode of ventilation could be useful when infants are to be weaned off the ventilator.
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In order to study if oxygen saturation in mixed venous blood (SvO2) could be used as a marker for heart performance, oxygen delivery (DO2) or consumption (VO2) in critically ill patients 134 hemodynamic measurements were performed by a thermodilution pulmonary catheter in 23 patients after abdominal aortic aneurysm surgery. These data were compared to 200 measurements performed in 30 patients with septic shock. When analysed on an individual basis SvO2 was only closely related to DO2 or VO2 in a minority of the patients. ⋯ On the other hand SvO2 was found to be an excellent marker for oxygen extraction (OER) in both groups of patients (median r = 0.98. p < 0.0001). In conclusion, the present study shows that SvO2 could not be used as a reliable marker for the important hemodynamic variables CI, DO2 or VO2 in critically ill patients. However, SvO2 was found to be an excellent marker for OER.
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This study was made to determine how oscillations superimposed on intermittent positive pressure ventilation (IPPV) influence the arterial blood gases, pH and the airway pressures during adequate alveolar ventilation i.e. at inhibition of inspiratory activity, before and after experimentally induced lung injury in the anaesthetized cat. Two IPPV frequencies were studied. The lung was injured by instillation of xanthine oxidase into the upper airways during IPPV. ⋯ Before lung injury, superimposed oscillations lowered the airway pressures only at an IPPV rate of 15 breaths per minute (b.p.m.). After lung injury, such oscillations increased the airway pressures only at 15 b.p.m. The airway pressures were always lower at 60 than at 15 b.p.m.
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Randomized Controlled Trial Clinical Trial
EMLA for pain relief during arterial cannulation. A double-blind, placebo-controlled study of a lidocaine-prilocaine cream.
The aim of the study was to evaluate the effect of a lidocaine-prilocaine cream (EMLA cream, Astra) in relieving pain during arterial cannulation. The study had a random, double-blind, placebo-controlled design and included altogether 90 patients. All the patients were premedicated with an opioid before cannulation. ⋯ Between these groups pain experience measured by VAS did not show any significant difference although the mean value was lower in the EMLA group. Observer ratings showed a significant (p less than 0.01) difference in distribution towards lower ratings in the EMLA group. In conclusion EMLA was found to have a weak, but measurable effect when the application time exceeded 90 minutes but not after 60 minutes.
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In early ARDS (Adult Respiratory Distress Syndrome) and other inflammatory pulmonary disorders the lung might benefit from a high local deposition of an active drug, in order to optimize the local concentration without systemic side effects. In this methodological study we used pigs under controlled ventilation. The study was carried out in two steps. ⋯ This study shows that it is possible, under reproducible conditions, to administer aerosolized Evans blue dye and liposomes and to achieve a deposition in the terminal airways and/or alveolar spaces. The broncho-alveolar lavage demonstrated an interaction of liposomes with alveolar macrophages. The results imply that liposomes carrying active drugs and administered by inhalation may be used for local pulmonary treatment in early ARDS and other related inflammatory pulmonary diseases.