Biomedical subjects

R A Rivera

Publications and source records attributed to R A Rivera.

15 recordsLinked to original sources

PubMed1992

The cardiovascular and haematological effects of purified prothrombin activator from the common brown snake (Pseudonaja textilis) and their antagonism with heparin.

The cardiovascular and haematological effects of purified prothrombin activator derived from the venom of the Australian Common Brown Snake (Pseudonaja textilis) were studied in anaesthetised, mechanically ventilated dogs. Severe depression of systemic blood pressure and cardiac output and a rise in central venous pressure were observed. Thrombocytopenia, prolongation of both prothrombin time and activated partial thromboplastin time and a reduction in serum fibrinogen were also observed. All of these observed effects were prevented by the prior administration of heparin--a naturally occurring anticoagulant. We conclude that the prothrombin activator in Pseudonaja textilis venom may cause cardiovascular depression due to myocardial dysfunction secondary to disseminated intravascular coagulation.

Animals↗

PubMed1990

Predictors of mortality in children with respiratory failure: possible indications for ECMO.

There are many unproven methods of ventilation and oxygenation that have been used in children dying from respiratory failure, including extracorporeal devices and high frequency ventilation. However, no objective predictors of death have been developed that enable clinicians to decide when it is reasonable to use these therapies in children over one month of age with acute respiratory failure. To determine predictors of death, we evaluated the charts of all 42 children aged one month to eighteen years admitted to the intensive care unit who were ventilated for more than twelve hours, received greater than 90% oxygen, received a peak inspiratory pressure greater than 25 cmH2O and had no pre-existing neurodevelopmental handicap. A combination of a variable reflecting ventilation and a variable reflecting oxygenation reliably predicted death: a combination of ventilation index greater than 40 and oxygenation index greater than 0.4 was associated with a 77% chance of mortality (sensitivity 65% and specificity 74%); a combination of peak inspiratory pressure greater than 40 cmH2O and A-aDO2 greater than 580 was associated with an 81% chance of mortality (sensitivity 74% and specificity 79%). These criteria may be useful in predicting death from respiratory failure in children.

Adolescent↗

PubMed1975

Trans-chest ventricular defibrillation of heavy subjects using trapezoidal current waveforms.

Effectiveness of four truncated exponential waveform defibrillators for transchest ventricular defibrillation was evaluated in 27 human-sized animals. With all waveforms, effectiveness was virtually 100% for small subjects, but decreased as body weight increased. These data confirm the electrical dose concept for ventricular defibrillation and demonstrate that the truncated exponential waveform is effective only when adequate current is delivered through the subject's chest.

Animals↗

PubMed1973