Cardiovascular regulation and lesions of the central nervous system

Cardiovascular regulation and lesions of the central nervous system

260 CPR) for one hour after the induction of ventricular fibrillation. All piglets received C-CPR. Animals received either no epinephrine, or a bolus...

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CPR) for one hour after the induction of ventricular fibrillation. All piglets received C-CPR. Animals received either no epinephrine, or a bolus of epinephrine (1 .O mg in dogs, 50 pg in piglets) at the onset of ventricular fibrillation, followed by a continuous infusion of 4 ,ug/kg/min. Three to six minutes after commencement of conventional CPR on dogs, cerebral and myocardial blood flow were significantly higher in the epinephrine group than in the nonepinephrine group (P< .Ol). During SVC-CPR in dogs at six minutes, cerebral and myocardial blood flow were higher in the epinephrine group, but the difference was not statistically significant. In the nonepinephrine group, however, aortic and carotid pressures fell after 20 minutes, but remained stable for one hour in the epinephrine group. In another group of dogs, SVC-CPR and epinephrine administration were delayed until five minutes after the induction of ventricular fibrillation. Compared with dogs who received immediate SVC-CPR and epinephrine, there were no significant differences between the total myocardial and cerebral blood flow at six minutes and during the remainder of the hour. In infant piglets, cerebral and myocardial blood flows were significantly greater in the epinephrine treated group (PC .Ol) at five minutes and remained higher with prolonged CPR. The authors conclude that the continuous infusion of epinephrine is beneficial in different age groups of different species owing to its effect of increasing cerebral and myocardial blood flow. This effect persists when the initiation of CPR has been delayed. [Kurt J. Wagner, MD]

TREATMENT OF PRESUMED ASYSTOLE DURING PREHOSPITAL CARDIAC ARREST. Ornato JP, Gonzales ER, Morkunas AR, et al. Am J Emerg Med 1985; 3:395-399. A prospective study was conducted to determine the efficacy of epinephrine, atropine, and calcium chloride as compared with electrical countershock in the treatment of asystolic cardiac arrest. All adult patients who suffered an out-ofhospital nontraumatic cardiac arrest and were brought to the University of Nebraska Medical Center by paramedics from December 1982 to January 1984 were entered into the study. Prehospital care was directed by physicians via radio telemetry to paramedics using standard American Heart Association protocols pertinent to the rhythm being treated. Three to five minCl

The Journal of Emergency Medicine

utes were allowed to elapse between each intervention to determine if a change in rhythm had occurred. Initial rhythm was defined as that first seen by the paramedics on the cardiac monitor; any rhythm appearing after advanced cardiac life support intervention was considered a late rhythm. Data were analyzed for rhythm-therapyrhythm sequences. The initial rhythms in the 83 adults studied were ventricular fibrillation (VF) in 44 (53%), asystole in 24 (29?‘0), idioventricular in 7 @To), supraventricular in 5 (6r70), and miscellaneous in 3 (4070).Of those patients initially in VF, 20 (46%) survived to hospital discharge; of those initially in asystole, none were discharged alive. When asystole was the initial rhythm, electrical countershock infrequently altered the rhythm. When asystole appeared later in resuscitation, however, countershock was significantly more effective than epinephrine (P< .003), atropine (P< .04), and CaCl (P< .03) in changing the rhythm. The data indicate that countershock appears to be superior to epinephrine, atropine, and CaCl for the treatment of asystole during the course of resuscitation. Furthermore, that ventricular fibrillation was the most common rhythm appearing after countershock for asystole suggests that asystole, when encountered during the course of resuscitation, may actually represent VF. The authors suggest that a reexamination of the standard protocols for treating asystole is needed and suggest that earlier countershock in apparently asystolic arrests may result in a greater chance of resuscitation and survival. [John L. Abt, DO]

0 CARDIOVASCULAR REGULATION AND LESIONS OF THE CENTRAL NERVOUS SYSTEM. Talman WT. Ann New-of 1985; 18: l-12. This article reviews the cardiovascular disturbances resulting from diseases of the CNS and discusses the clinical and laboratory evidence supporting a neuronal and neurohumeral relationship between the CNS and cardiovascular system. CNS disease has been shown to directly cause cardiovascular abnormalities. Secondary ECG changes have been reported to occur in 60% to 70% of subjects with intracerebral hemorrhage, in 15% to 4O(r/oof patients with nonhemorrhagic stroke, and in 40% to 70% of those with subarachnoid hemorrhage. Most commonly these changes include ST segment depression, T wave inversion, a prolonged QT interval, and

Abstracts

U waves. Less frequently peaked T waves, elevated ST segments, and Q waves have been described. Observation of such patients has revealed that the ST-T wave changes revert to pre-CNS event patterns within 2 weeks and that they are without evidence of myocardial injury. The overall prognosis of patients with ECG changes secondary to CNS events is considerably worse than in patients without ECG changes. Cardiac dysrhythmias associated with CNS disease include supraventricular tachycardia, premature ventricular contractions, and ventricular fibrillation and flutter. It is unclear whether dysrhythmias are induced by direct neural stimulation or are secondary to myocardial damage caused by elevated catecholamine levels, which have been observed during acute CNS disease. The role of the parasympathetic system in these changes is yet unsettled. [Jerry Mueller, MD] Editor’s Note: This is an interesting in-depth review of the ECG changes accompanying acute CNS events, an occurrence that often provides a diagnostic dilemma to the physician initially treating the undifferentiated comatose patient.

0 PEDIATRIC EMERGENCY INTRAVENOUS ACCESS. Kanter RK, Zimmerman JJ, Strauss RH, Stoeckel KA. Am J Dis Child 1986; 140:132-134. The authors undertook a prospective study to assess the effectiveness of a protocol for rapid emergency intravenous (IV) catheterization in a pediatric population and to test the hypothesis that IV access could be more rapidly achieved when protocol compliance was attained rather than when deviations from the protocol occurred. The use of multiple-standard IV techniques applied in a rapid sequential fashion was designed to achieve IV access during the first five minutes of resuscitation. The protocol began with a 1 %minute period in which attempts were made to insert a peripheral percutaneous IV. If insertion was unsuccessful after the allotted time, during the next 3 % minutes efforts were made to simultaneously insert a femoral vein catheter percutaneously and to perform a saphenous vein cutdown on the contralateral limb. When personnel were available, attempts to begin a percutaneous peripheral IV were continued. If IV access had not been obtained within five minutes, indirect

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IV access was obtained via intraosseous infusion using a site 1 to 3 cm below the tibia1 tuberosity. To test the protocol, resuscitations of 38 pediatric patients requiring cardiopulmonary resuscitation without preexisting IV access were evaluated. Intravenous access was successfully achieved in 36 (95%) of the resuscitations. Although no single IV technique provided completely reliable and rapid IV access, utilization of all techniques per protocol significantly improved IV access time. In the 29 patients in whom initial percutaneous peripheral IV attempts failed, compliance with the protocol achieved IV access in 4.5 minutes, compared with 10.0 minutes when the protocol was not followed. Although cutdowns were successful in 8 1% of the patients in whom they were attempted, in more than half of these another route of access had been obtained before the cutdown was completed. The authors conclude that emergency IV access during the first five minutes of a pediatric resuscitation is possible if all available IV techniques are utilized. [Liz Yedlicka, MD] Editor’s Note: The authors provide a reasonable and apparently effective method for attaining rapid IV access during pediatric resuscitations.

0 SEPTIC ARTHRITIS IN CHILDHOOD. Sequeira W, Swedler WI, Skosey JL. Ann Emerg A4ed 1985; 14:1185-l 187.

The authors retrospectively reviewed the joint fluid cultures and clinical records of 32 patients with septic arthritis who were less than 16 years of age and who presented over a IO-year period to Cook County Hospital. All patients were black, reflecting the predominant racial makeup of the hospital’s patient population. Ages ranged from 12 days to 15 years. The knee and hip were the joints most frequently involved, accounting for 12 (37%) and 9 (27%) of the cases, respectively. All patients had a peripheral leukocytosis. Haemophilis influenzae was the most common organism isolated from the joint fluid; it was isolated from 37% of all cases and from 64% of the children less than 2 years of age. Associated upper respiratory tract infection was present in 75%. Staphylococcus aureus was seen in seven of the eight (87.5%) children above the age of 5 and was associated with trauma in 77% of these cases. No patient had sickle cell disease. [Douglas Davenport, MD]