Hypertonic/hyperoncotic treatment for brain damage.
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Brain Injuries↗
Biomedical subjects
M Rocha-e-Silva
Publications and source records attributed to M Rocha-e-Silva.
Effects of hypertonic saline dextran on the postoperative evolution of Jehovah's Witness patients submitted to cardiac surgery with cardiopulmonary bypass.
Hypertonic saline-dextran (HSD) solutions have been used for hemorrhagic shock, aortic aneurysm, and cardiopulmonary bypass surgery (CPB). Jehovah's Witness patients refuse blood and derivatives even under life-threatening conditions. A negative fluid balance for Jehovah's Witnesses would avoid further hemodilution. In this study we compared clinical, hemodynamic, laboratory evolution, and fluid balance of 20 Jehovah's Witnesses over the first 72 h following CPB. Ten received HSD immediately prior to CPB. All patients survived and were maintained in stable hemodynamic and metabolic condition throughout the study period. HSD induced high cardiac output, low vascular resistance immediately after administration. Vascular resistance remained low until the end of CPB. HSD patients ran a slightly negative fluid balance, while control patients ran a large positive fluid balance. HSD pretreatment is now used routinely for Jehovah's Witnesses undergoing CPB in our facility.
Adult↗
A quantitative analysis of transcapillary refill in severe hemorrhagic hypotension in dogs.
In pressure-driven hemorrhage (PDH), where the rate of bleeding is a function of prevailing arterial pressure, survival time, arterial pressure, cardiac output, oxygen consumption, and base excess are functions of initial bleeding rate. The quantitative rate of transcapillary refill (TR) throughout PDH leading to death was determined in splenectomized dogs, through serial analysis of Cr51-tagged red cell dilution. Mild, moderate, and severe levels of PDH were produced by varying initial bleeding rate (10, 25, and 50 ml/min, respectively). The rate of TR is a function of the severity of PDH, but does not correlate with arterial pressure, cardiac output, or systemic resistance. The volume of transferred fluid represents an ever increasing fraction of total plasma volume, and accounts for more than 75% of plasma volume in preterminal stages of shock. TR sustains a relatively fixed level of plasma volume, equivalent to two-third of the initial plasma volume, irrespective of the rate of bleeding. Hypertonic NaCl (7.5%) enhances TR, while isotonic NaCl reverses it.
Animals↗
Inotropic effect of hyperosmotic NaCl solutions on the isolated rat cardiac tissue.
The inotropic effect of Krebs-Henseleit solution rendered hyperosmotic by addition of NaCl or sucrose (increments of 50, 100, 150 and 200 mOsm/l) on myocardial contractile activity was studied in rat isolated left atria paced at 4, 16 and 64 stim/min. The solutions did not affect the peak tension (Tp) at 4 stim/min, whereas sucrose caused a dose-dependent increase in Tp at 16 stim/min and NaCl decreased Tp at 64 stim/min. The total time duration of the contraction was increased in a dose-dependent fashion by both solutes, but the effect of NaCl was attenuated at 64 stim/min. The results showed that, in the isolated rat atrial tissue exposed to hyperosmotic NaCl solutions, the negative inotropic effect of increased Na+ concentration overcomes the positive influence of hyperosmolality only at higher pacing rates (about 1 Hz).
Animals↗
A portable microprocessor-based triggering device for cardiac muscle electrical stimulation.
We describe a microprocessor-based programmable triggering instrument designed to control the distribution in time of electrical stimuli delivered to a heart muscle preparation. Sequences of stimuli may be selected among those stored in the non-volatile memory of the instrument and new sequences may be programmed using a repertory of 25 commands. The instrument was used to study the inotropic effects of three irregular sequences of stimuli applied to the isolated rat left atrium. The mean peak tension developed by the tissue was unaltered by stimulus sequence, provided the mean stimulatory frequency (2 or 5 Hz) was maintained. The instrument may be useful to study the effect of different stimulatory patterns on cardiac inotropism, as well as for controlling the electrical stimulation of other biological preparations.
Animals↗
Hypertonic saline resuscitation is prevented by intracerebroventricular saralasin but not by captopril.
Hypertonic saline resuscitation (HR, 7.5% NaCl, 4 ml/kg) effectively reverts severe hemorrhage, but a central neural component is probably involved in the survival response. This experiment examines the role of central angiotensinergic pathways in hemorrhage-hypertonic resuscitation interaction. Severely bled (43 +/- 2 ml/kg) pentobarbital-anesthetized dogs with chronically implanted cerebral ventricular cannulae were resuscitated with 4 ml/kg 7.5% NaCl, iv 10 min after intracerebroventricular injection of 0.5 ml normal saline (CT), 150 micrograms saralasin (in 0.5 ml saline, SR), or 10 mg captopril (in 0.5 ml saline, CP). All 10 SR-treated dogs died 2-6 h after HR. Their arterial pressure and cardiac index initially recovered to near pre-hemorrhage levels, but gradually decreased thereafter, base excess remaining at severe metabolic acidosis levels throughout. All CT- and 8/10 CP-treated dogs survived indefinitely, with near normal arterial pressure, cardiac index and base excess levels. It is therefore concluded that the inhibition of central angiotensinergic sites with the competitive antagonist saralasin effectively prevents survival after HR, whereas inhibition of angiotensin converting enzyme by captopril in cerebrospinal fluid is virtually ineffective.
Animals↗
Hypertonic NaCl antagonizes cardiac arrhythmia induced by bupivacaine.
We studied the effects of pretreatment with hypertonic solutions on the conduction disturbances and cardiac arrhythmias caused by iv injection of bupivacaine in anesthetized mongrel dogs. Bupivacaine was injected in doses of 3 mg/kg and 6.5 mg/kg. The hypertonic solutions used were: 7.5% NaCl, 5.4% LiCl, 50% Glucose (5 ml/kg) and 20% mannitol (10 ml/kg). Bupivacaine induced severe conduction disturbances, as reflected by significant increases in QRS complex duration, HV interval and IV interval, and severe hypotension. The arrhythmias observed were: sinus node dysfunction, nonsustained ventricular tachycardia, sustained ventricular tachycardia and ventricular fibrillation. These effects were dose dependent, and were more evident with the higher dose of bupivacaine. Among all the hypertonic solutions tested, only 7.5% NaCl effectively protected against conduction disturbances and cardiac arrhythmias. These findings suggest an important role for sodium overload in these situations and provide a potentially harmless tool for the treatment of anesthetic accidents with bupivacaine during regional anesthesia.
Animals↗
Chronotropic and inotropic effects of hyperosmotic solutions on right and left atria isolated from the rat heart.
The chronotropic and inotropic effects of hyperosmotic solutions (HS) on isolated rat atria were studied to determine the influences of solute, time and blockade of autonomic receptors. NaCl and sucrose HS (450 mOsm/1) exerted a time-dependent negative chronotropic effect on right atria. NaCl decreased whereas sucrose increased peak tension of the left atria. Phenoxybenzamine and propranolol did not change the chronotropic effects of hyperosmolality, but increased the peak tension of left atria exposed to HS. We conclude that chronotropic effects of HS seem to be non-specific while inotropic effects depend on the solute and may involve neurotransmitter release, probably acetylcholine.
Acetylcholine↗
Hypertonic resuscitation from severe hemorrhagic shock: patterns of regional circulation.
Severe blood loss can be reverted to normal circulatory function and indefinite survival by a small volume of 2,400 mOsm/liter NaCl (7.5%). This response requires functioning cervical vagal trunks at the time of hypertonic injection. Other equally hypertonic solutes (glucose, mannitol) are ineffective. This paper examines the effects of hypertonic (2,400 mOsm/liter) NaCl (7.5%) and glucose (50%) on femoral, mesenteric, splanchnic, renal, and coronary circulations. Hypertonic NaCl was given to dogs with intact or blocked vagi. Femoral flow was measured in innervated or denervated hindlimbs. Hemorrhage severely restricted both innervated and denervated femoral flows. Hypertonic glucose and NaCl, vagi blocked, redilated both femoral territories. Hypertonic NaCl, intact vagi, redilated denervated femoral vasculature but severely restricted innervated flow. Renal, mesenteric, total splanchnic, and coronary flows were restricted by hemorrhage and undistinguishable redilated by glucose or NaCl, blocked or intact vagi. It appears therefore that hypertonic NaCl induces permanent survival, partly because of its ability to elicit a pulmonary reflex, which induces muscular/cutaneous precapillary constriction. This shunts essentially required flow into the viscera, which are unspecifically vasodilated by hypertonicity.
Animals↗
Treatment of refractory hypovolaemic shock by 7.5% sodium chloride injections.
Injections of hyperosmotic (7.5%) sodium chloride (100-400 ml) were given to 12 patients in terminal hypovolaemic shock who had not responded to vigorous volume replacement and corticosteroid and dopamine infusions. Hyperosmotic sodium chloride promptly reversed the shock in 11 of these patients. The immediate effects of the NaCl injections were a moderate rise in arterial pressure, the resumption of urine flow, and recovery of consciousness. These effects tended to persist for a few hours. The hyperosmotic infusion also reduced isosmotic fluid requirement by 90%.
Adult↗