Resuscitation
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We report echocardiographic observations during external chest compression in a patient with marked abnormalities in thoracic anatomy following emergency surgery of aortic arch aneurysm. Transesophageal echocardiography demonstrated direct right ventricular, aortic and left atrial compression, only minimal left ventricular compression and an open mitral valve during closed chest heart massage. Colour flow doppler demonstrated forward blood flow across the mitral valve and along the left ventricular outflow tract during the compression phase. Echocardiographic findings indicate that factors apart from simple cardiac pump mechanism contributed to blood flow during cardiopulmonary resuscitation (CPR) in this postoperative patient after a major thoracic surgical intervention.
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Comparative Study
Ventilation caused by external chest compression is unable to sustain effective gas exchange during CPR: a comparison with mechanical ventilation.
To compare the tidal volume, minute ventilation, and gas exchange caused by mechanical chest compression with and without mechanical ventilatory support during cardiopulmonary resuscitation (CPR) in a laboratory model of cardiac arrest. ⋯ Standard chest compression alone produced measurable tidal volume and minute ventilation. However, after 10 min of chest compression following 6 min of untreated ventricular fibrillation, it failed to sustain pulmonary gas exchange as indicated by significantly greater arterial and mixed venous hypercarbic acidosis when compared with a group receiving mechanical ventilation.
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This investigation was designed to evaluate the changes in arterial and mixed venous acid-base conditions during untreated ventricular fibrillation and after institution of cardiopulmonary resuscitation (CPR). Fifty-two swine (weight: 25-40 kg) were studied after induction of ventricular fibrillation. In a subgroup of 10 animals, 10-min CPR trials were performed. ⋯ We conclude that untreated cardiac arrest may be accompanied by normal arterial and mixed venous blood gas levels. Tissue acidosis is only revealed after tissue perfusion is restored and is most accurately reflected in the mixed venous blood gas composition. This apparent paradox provides insight into the relationship between tissue perfusion and arterial and mixed venous acid-based composition.
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Previous work has shown that insertion of the laryngeal mask airway is a skill that is easily taught to inexperienced operators. In this study we have assessed the ability of non-anaesthetists to maintain an airway in a paralysed, anaesthetised patient in the controlled setting of an anaesthetic room. ⋯ The inspired volume delivered to the patients was standardised using a Penlon Nuffield ventilator attached to the breathing system. Our results showed no difference in success in maintaining the airway between the three techniques or in the mean expired volumes achieved during successful ventilation.