Annals of emergency medicine
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Comparative Study
Transcutaneous oxygen tension measurements during graded hemorrhage and reinfusion.
Measurement of transcutaneous oxygen tension (PtCO2) has been suggested as a useful monitoring tool in the hypovolemic patient. Our study was undertaken to evaluate changes in PtCO2 that occur during graded hemorrhage and reinfusion, and to compare PtCO2 values to standard cardiorespiratory and biochemical parameters during hypovolemia. Seven mongrel dogs were bled 50% of their estimated blood volume (44 mL/kg) over one hour. ⋯ In contrast to the other measured variables, the elevations in PtCO2, and MvO2 were more pronounced early in the reinfusion period. During postreinfusion monitoring, PtCO2, MvO2, CO, and PCWP fell significantly despite maintenance of prehemorrhage MAP and CVP. Overall PtCO2 correlated well with MvO2 and the O2 extraction ratio, and to a lesser extent with CI, MAP, and O2 delivery.(ABSTRACT TRUNCATED AT 250 WORDS)
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The challenge of the 1960s to ambulance care provision was the stimulus for the emergence of prehospital advanced life support (ALS) being provided by paramedic personnel. While services for cardiac disease have been accepted, paramedic activities for the trauma victim continue to be a concern for many trauma surgeons. The capability and success rate of treatment, and the time spent at the scene and during transport to the hospital have raised questions about the overall need for paramedic services. ⋯ Scene time of patients with unsuccessful IV and endotracheal intubation was 14 minutes (P = .07). Fourteen patients (14.7%) were admitted to the operating room or intensive care unit. Only three of the study group (3.2%) survived.
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Comparative Study
Comparison of central venous and arterial pH and PCO2 during open-chest CPR in the canine model.
Arterial blood gases are difficult to obtain during cardiopulmonary resuscitation (CPR) in human beings, and the possibility of venous sampling is raised frequently. The reliability of central venous gases as a substitute for arterial blood gases in assessing acid base status, however, has not been investigated adequately under conditions of CPR. Therefore, femoral arterial and central venous catheters were placed in 24 mongrel dogs, and ventricular fibrillation was electrically induced. ⋯ The ability of pHcv to substitute for pHa was assessed, and showed a sensitivity of 100% when pHa of 7.2 was used as a criterion for treatment. In this model, pHcv is a sensitive indicator of pHa and it may be used to guide bicarbonate therapy. The increased PcvCO2 during CPR probably results from the marked tissue lactic acid production and subsequent shift of the bicarbonate buffer into free carbon dioxide.
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To determine if clinically accessible hemodynamic and blood gas measurements are of value in predicting outcome of countershock after prolonged ventricular fibrillation (VF) and artificial cardiopulmonary support, 14 dogs were studied during 30 minutes of VF using two randomly assigned closed-chest techniques. Seven dogs underwent conventional CPR; the other seven were supported with a pneumatic thoracic vest and abdominal binder, which were inflated synchronously with the airway. Ascending aortic (Ao), right atrial (RA), and instantaneous coronary perfusion pressures (Ao - RA) were measured at five-minute intervals. ⋯ Six animals developed a perfusing cardiac rhythm after one or more countershocks (Group 1); eight failed to develop a perfusing rhythm after repeated countershocks and an additional 30 minutes of resuscitative effort (Group 2). Five Group 1 dogs received vest/binder artificial support. When measured values were averaged over the study period, Group 1 was found to have a significantly greater Ao end-diastolic pressure (AoEDP) and peak diastolic coronary perfusion pressure (CPP) when compared to Group 2 (23 +/- 6 vs 14 +/- 8 mm Hg, P less than .05; and 22 +/- 6 vs 5 +/- 10 mm Hg, P less than .01, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)
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Adequate positive pressure ventilation in the field or emergency department continues to represent a major challenge. A new face mask design that recently has been introduced consists of a low-pressure "balloon" through which a Guedel airway is attached and extended proximally through the mask to allow the attachment of a ventilation bag. The mask is designed to seal the nares and mouth when pressed against the face. ⋯ Volunteers ventilated the test lung using three masks in random sequence: the SealEasy mask (Respironics Inc, Monroeville, PA), a Laerdal mask (old type), and a transparent Robertshaw mask with inflatable black rim. The average tidal volume delivered by the SealEasy mask was consistently higher than either of the other two. Significantly (P less than .05) higher volumes were delivered with the SealEasy mask when compared to the Laerdal, and significantly lower mask leaks were seen when the SealEasy was compared to both.(ABSTRACT TRUNCATED AT 250 WORDS)