[Extrahospital cardiac arrest: the experience of Mestre Emergency Service]. / Arresto cardiaco extraospedaliero: l'esperienza di Mestre Emergenza.

BACKGROUND: Out-of-hospital cardiac arrest (AC) is one of the leading causes of death in industrialized countries. AC-related mortality can be reduced by rapid intervention. We report the experience of the emergency medical service (EMS) of Mestre on the management of out-of-hospital AC. METHODS: We analyzed 80 cases of out-of-hospital AC observed consecutively by the EMS of Mestre from February 1996 to September 1997: 72 cases (90.0%) involved cardiac etiology and 8 (10.0%) non-cardiac etiology. The 72 cases involving cardiac etiology were divided in three groups: group A) 12 unwitnessed ACs (16.7%); group B) 12 ACs witnessed by EMS personnel (16.7%); group C) 48 bystander-witnessed ACs (66.6%). RESULTS: In group A, in which 4/12 patients (33.3%) presented ventricular fibrillation (FV) or pulseless ventricular tachycardia (TV) as initial rhythm, return of spontaneous circulation (ROSC) was obtained in one patient with FV and in one patient with asystole. In group B, 7/12 patients (58.3%) presented FV or TV as initial rhythm; in this subgroup, ROSC was obtained in 71.4% of cases (4 cases with FV and one case with TV) and discharge in 42.9%, while in the subgroup with other rhythms the rate of ROSC was 40.0% (two patients with pulseless electrical activity later died). In group C, 35/48 patients (72.9%) presented VF or TV as initial rhythm; in this subgroup, ROSC was achieved in 42.9% of cases (13 cases with FV and 2 cases with TV) and discharge in 14.3%, while in the subgroup of bystander-witnessed AC with other rhythms the rate of ROSC was extremely low (7.7%) (one patient with asystole later discharged). In group C, bystander cardiopulmonary resuscitation (CPR) was performed in 20/48 patients (40.1%). In these patients, FV or TV were more frequently recorded as initial rhythm (80.0 vs 67.9%; p < 0.05). In patients without bystander CPR, the interval between the time of collapse and the time of the first defibrillation was shorter in the patients who were admitted than in patients who died (6.0 +/- 1.4 vs 10.9 +/- 4.4 min; p < 0.05). Considering all patients with FV or TV as initial rhythm and the interval between the collapse and the first defibrillation exactly recorded, the percentage of ROSC decreased when the interval between the collapse and the first defibrillation increased. CONCLUSIONS: Our data confirm that early defibrillation is the key factor in the prognosis of out-of-hospital AC. The data suggest that the immediate delivery of bystander CPR could extend the interval in which defibrillation is effective.

Evaluation of atrial vulnerability with transoesophageal stimulation in patients with atrioventricular junctional reentrant tachycardia. Comparison with patients with ventricular pre-excitation and with normal subjects.

The aim of our work was to evaluate the inducibility of atrial fibrillation in a group of patients with atrioventricular junctional reentrant tachycardia and to compare it with that of patients with a Kent-type ventricular pre-excitation (Wolff-Parkinson-White syndrome) and a control group. One hundred and twenty-five subjects were separated into groups. Group 1 comprised 49 Wolff-Parkinson-White patients, with a mean age of 26.4, range 10-66 years; group 2, 51 patients with atrioventricular junctional reentrant tachycardia inducible by transoesophageal atrial stimulation and/or clinically documented, with a mean age of 43.4, range 16-78 years; group 3, 25 control subjects with a mean age of 26.4, range 13-76 years. Each subject underwent atrial transoesophageal stimulation with the following protocol: programmed atrial stimulation with 1 and 2 stimuli during atrial pacing of 100.min-1 and 150.min-1; atrial stimulation for 10 s at a rate of 200-300-400-500-600.min-1 with intervals of 10 s between stimulations, five successive 'ramp-up' atrial stimulations for 9 s with the rate increasing from 100 to 800.min-1 with intervals of 10 s between stimulations. The end point was the completion of the protocol or induction of sustained atrial fibrillation (> 1 min). The chi-square test was used for statistical analysis. Our results showed that in group 1 atrial fibrillation was induced in 27/49 patients (55.1%); this was sustained in 13/49 (26.5%) and non-sustained in 14/49 (28.5%); in group 2, atrial fibrillation was induced in 22/51 patients (43.0%); it was sustained in 7/51 (13.7%) and non-sustained in 15/51 (29.4%); in group 3, sustained atrial fibrillation was not induced in any subject and in only one subject was a non-sustained atrial fibrillation (4 s) induced. The chi-square test showed that group 2 vs group 1 were non-significant, while group 2 vs group 3 and group 1 vs group 3 were significant (P < 0.003 and P < 0.0007, respectively). Therefore group 2 patients showed a greater atrial vulnerability in comparison to the control subjects and a similar vulnerability to group 1 patients. It is possible that the greater atrial vulnerability in the patients of group 2 was due to the double nodal pathway.

[The behavior of the arterial pressure at rest and under exertion in normotensive and hypertensive subjects exposed to acute hypoxia at a median altitude]. / Comportamento della pressione arteriosa a riposo e da sforzo in normotesi e ipertesi sottoposti a ipossia acuta da media quota.

In order to evaluate blood pressure changes at rest and during effort in response to moderate altitude acute hypoxia, we performed noninvasive blood pressure monitoring and maximal bicycle stress testing in 10 normotensive and 13 untreated mild hypertensive subjects at sea-level and in a mountain resort (m. 2572). Blood pressure was measured every 10 minutes by the Spacelabs 5200 pressurometer and bicycle stress test was performed at initial workload of 50 watts and steps of 50 watts every 3 minutes until exhaustion. Mean systolic blood pressure resulted unchanged in the normotensive subjects (120.8 +/- 10.6 vs 121.5 +/- 6.9 NS) while in the hypertensive ones it increased slightly at 2572 m. (131.0 +/- 12.3 vs 137.0 +/- 13.1 NS). Mean diastolic blood pressure did not increase significantly at 2572 m in either group (respectively from 74.5 +/- 90 to 80.1 +/- 7.9 NS and from 88.3 +/- 10.2 to 94.7 +/- 10.7 NS) even if blood pressure increase was relevant in some hypertensive subjects. During the monitoring, heart rate increased at 2752 m in both groups, even if this difference was significant in the hypertensive group only (respectively 82.8 +/- 11.8 vs 94.3 +/- 13.2 in normotensive subjects-NS-and 88.0 +/- 6.3 vs 104.0 +/- 7.8 in hypertensive subjects-p less than 0.001). During the ergometric test submaximal systolic blood pressure (100 and 150 watts) increased slightly in both groups, but this difference was significant in hypertensive subjects at a workload of 150 watts only (208.3 +/- 18.2 vs 219.3 +/- 19.2 p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)