Vasopressin deficiency contributes to the vasodilation of septic shock

BACKGROUND

The hypotension of septic shock is due to systemic vasodilation. On the basis of a clinical observation, we investigated the possibility that a deficiency in vasopressin contributes to the vasodilation of septic shock.

METHODS AND RESULTS

In 19 patients with vasodilatory septic shock (systolic arterial pressure [SAP] of 92 +/- 2 mm Hg [mean +/- SE], cardiac output [CO] of 6.8 +/- 0.7 L/min) who were receiving catecholamines, plasma vasopressin averaged 3.1 +/- 1.0 pg/mL. In 12 patients with cardiogenic shock (SAP, 99 +/- 7 mm Hg; CO, 3.5 +/- 0.9 L/min) who were also receiving catecholamines, it averaged 22.7 +/- 2.2 pg/mL (P < .001). A constant infusion of exogenous vasopressin to 2 patients with septic shock resulted in the expected plasma concentration, indicating that catabolism of vasopressin is not increased in this condition. Although vasopressin is a weak pressor in normal subjects, its administration at 0.04 U/min to 10 patients with septic shock who were receiving catecholamines increased arterial pressure (systolic/diastolic) from 92/52 to 146/66 mm Hg (P < .001/P < .05) due to peripheral vasoconstriction (systemic vascular resistance increased from 644 to 1187 dyne.s/cm5; P < .001). Furthermore, in 6 patients with septic shock who were receiving vasopressin as the sole pressor, vasopressin withdrawal resulted in hypotension (SAP, 83 +/- 3 mm Hg), and vasopressin administration at 0.01 U/min, which resulted in a plasma concentration (approximately 30 pg/mL) expected for the level of hypotension, increased SAP from 83 to 115 mm Hg (P < .01).

CONCLUSIONS

Vasopressin plasma levels are inappropriately low in vasodilatory shock, most likely because of impaired baroreflex-mediated secretion. The deficiency in vasopressin contributes to the hypotension of vasodilatory septic shock.

Development of an intraluminal device for the treatment of aortic regurgitation: prototype and in vitro testing system

OBJECTIVES

Development of an intraluminal device to reduce aortic regurgitation could provide a strategy intermediate between medical treatment and aortic valve replacement. An initial prototype and a testing system have been designed.

METHODS

Aortic valves obtained from heart transplant recipients were explanted and assessed in a mock circulatory loop with resistive and capacitive elements, including pressure-flow characteristics, similar to those of a normal arterial system. Normal heart function was simulated by a pulsatile ventricular-assist device. Pressure on each side of the valve and flow through the valve were recorded, allowing the calculation of regurgitant fractions and transvalvular gradients. Six solid geometrically differing obturators were tested.

RESULTS

All six designs resulted in significant reduction in aortic regurgitation (p < 0.0001), ranging from 15% to 38% improvement compared with control values. Small increases in transvalvular gradients (from 0 to 7 mm Hg) were also noted.

DISCUSSION

Initial results suggest that an intraluminally placed obturator can reduce aortic regurgitation without creating clinically significant transvalvular gradients. These initial in vitro experiments demonstrate the feasibility of an intraluminal device for the treatment of aortic valve disease, and further investigation is warranted.

[Incidence of Haemophilus influenzae type b meningitis in Italy. Preliminary results]

The Authors describe the survey's results aimed at quantifying the Haemophilus influenzae type b meningitis incidence rate in Italy. The survey collected all the cases of 1994 notified per region to the Ministry of Health; furthermore, regional incidence rates are compared and integrated with other data obteined from local ad hoc studies. The results obtained show a high incidence in the age group 0-2 years and a large discrepancy in the incidence rate between regions (from 0.0 to 16.8 cases per 100,000); furthermore, in the same age group, for a large amount of meningitis cases (18% of the total) the aetiological diagnosis was not successful; this phaenomenon is certainly one of the causes for the underestimation of the disease. The integration with data collected in longitudinal studies, increases largely the regional incidence rate, showing the highest rate in the Lazio Region (18.5 cases per 100,000). The Authors conclude by stressing the need to increase the cooperation between the Regional Health Authorities and the Ministry of Health, in order to obtain more reliable figures of the national incidence rates.

[General practice and preventive activities in a Local Health Unit in Lazio]

The Authors describe the results of a survey addressed to evaluate GP's opinions and behaviours regarding prevention. The GP's report they offer health informations about cardiovascular diseases and diabetes very often (score 3.6 and 3.4) and junior doctors (under 45 year) satisfy this request significantly more than senior doctors (p = 0.0057). The GP's consider their clinics the best place were to carry out health promotion activities (score: 3.8) and 85% of them would like to have a health promotion centre within their District (in italian: Local Health Unit), mainly to increase the coordination of GP's activities.

Attitudes and behavior of health care personnel regarding influenza vaccination

This paper reports the results of a study conducted by the Italian Association for Immune-Prophylaxis Promotion (AIP.I) with the aim of surveying the attitudes and perceptions of Italian health care workers regarding the use and efficacy of influenza vaccine. The results clearly show that a high proportion of the questioned health care workers showed a general lack of concern about the severity of the disease. Doubts about vaccine efficacy and fear of post-vaccination side effects were also observed to have an important influence on the vaccination acceptance rates. These data underline the need for a systematic education program to provide influenza vaccination within the public and private health-care sectors in Italy.