Intensive care medicine
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Intensive care medicine · Jan 1989
Diazepam does not improve the mechanical performance of rat cardiac papillary muscle exposed to chloroquine in vitro.
Diazepam has been reported to decrease the cardiac toxicity of chloroquine but the precise mechanism involved remains unknown. Left ventricular papillary muscles from adult Wistar rats were exposed to 10(-4) M chloroquine and assigned to three groups: group I (n = 10) exposed to chloroquine alone; group II (n = 8) exposed to chloroquine and 10(-5) M diazepam; group III (n = 8) exposed to chloroquine and 10(-4) M diazepam. The main mechanical parameters measured were: maximum unloaded shortening velocity (Vmax), maximum lengthening velocity (maxVr), active force normalized per cross-sectional area (AF/s), contraction-relaxation coupling under low load (R1), load sensitivity of relaxation (Isot. ⋯ A/Isom. A (113 +/- 9, 108 +/- 3, 109 +/- 7), or Emax (75 +/- 10, 81 +/- 12, 72 +/- 16). Chloroquine was shown to be a negative inotropic agent since it decreased Vmax, AF/s and Emax, but diazepam did not restore the intrinsic mechanical performance of rat cardiac papillary muscle exposed to chloroquine, therefore 1) the protective cardiovascular effects of diazepam in chloroquine poisoning are not related to an improvement in intrinsic cardiac mechanical properties; 2) inotropic agents are therefore necessary in combination with diazepam for the treatment of severe chloroquine poisoning.
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Intensive care medicine · Jan 1989
Comparison of epinephrine and dopamine during cardiopulmonary resuscitation.
The effectiveness of epinephrine and dopamine for restoring spontaneous circulation after asphyxial or fibrillatory cardiac arrest was compared using a porcine model. Asphyxial arrest: 7 animals received 45 micrograms/kg epinephrine, 7 animals 2.5 mg/kg dopamine, the remaining 7 animals received no drug treatment. All 7 animals given epinephrine could be resuscitated after 174 +/- 53 s, spontaneous circulation could be restored in only 3 of 7 animals given dopamine after 487 +/- 63 s and in none of the control animals could spontaneous circulation be established. ⋯ In the absence of either drug or mechanical measures and with mechanical measures only, spontaneous circulation could not be established in any of the cases. After administration of epinephrine, defibrillation and restoration of spontaneous circulation was achieved in 6 of 7 animals in 667 +/- 216 s, with dopamine, all the animals could be successfully resuscitated in the shorter time of 174 +/- 85 s. Epinephrine was found to be superior to dopamine in the treatment of asphyxial arrest whereas dopamine was found to be better in the management of ventricular fibrillation, probably by improving the balance between myocardial oxygen supply and demand.