Cardiorespiratory reflex effects induced by intravenous administration of ethanol in rats

Intravenous administration of a bolus of ethanol (40 mg/100 g b.w.) to rats induced bradycardia, hypotension and apnea. Bradycardia was dose dependent (r = -0.78, p less than 0.001). Acute bilateral vagotomy blocked bradycardia and hypotension. Apnea, however, persisted in all cases but was of short duration and occurred after a significant delay as compared to an untreated group. Atropine (0.1 mg/100 g b.w.) and hexamethonium (0.75 mg/100 g b.w.) blocked bradycardia and early hypotension. Pretreatment with reserpine (0.25 mg/100 g b.w. IP 24 and 48 hours before the experiment) significantly increased bradycardia induced by ethanol as compared to untreated animals. In rats pretreated with reserpine and vagotomized, IV ethanol did not induce bradycardia, early hypotension or apnea. A bolus of ethanol (20 mg/100 g b.w.) given directly into the left ventricle did not induce reflex changes in heart rate or respiration, while the same dose of alcohol given IV decreased heart rate by 53 +/- 8.9%. Thus, the ethanol effect seems to be initiated in pulmonary J receptors. Bradycardia appeared to be mediated both by increase in vagal tone, and to a lesser extent, by sympathetic withdrawal. Hypotension was due mainly to bradycardia, and apnea might be caused by a dual mechanism, reflex (early) and direct on the respiratory center (late).     

Assaults on psychiatrists by patients.

The authors describe the results of a survey of 115 psychiatrists regarding assaults by patients. Forty-eight psychiatrists stated that they had been assaulted; a total of 68 assaults was reported. Psychiatrists were most often assaulted in the early stages of their career or while they were working in high-risk settings such as prisons or emergency rooms. Many reported retrospectively that they might have had a role in provoking the assault and that they could have anticipated it. The authors believe that psychiatrists avoid dealing with the issue of violence by patients for a variety of reasons, and they recommend that clinicians learn techniques for managing potentially assaultive patients.     

Influences of changes in calcium concentration and verapamil on the cardiac depressant effect of ethanol in cat papillary muscle.

1. In isolated cat heart papillary muscle electrically driven at a constant rate the depressant effects of increasing concentrations of ethanol on peak tension developed (PTD) was studied in Ringer-Locke solution with different calcium concentrations and with the addition of verapamil. 2. Ethanol induced a concentration dependent decrease in PTD that was significantly greater for each concentration of ethanol in hypocalcic medium (1.1 mM) than in normocalcic medium (2.2 mM). 3. In normocalcic (2.2 mM) medium, verapamil (5.1 x 10(-4) mM) plus ethanol (48.6 and 97.2 mM) produced a decrease in PTD to values significantly greater than those obtained by the addition of ethanol and verapamil alone. Therefore a potentiation of the effects of ethanol by verapamil was observed when both drugs act simultaneously. 4. In hypercalcic medium (4.4 mM), verapamil plus ethanol (48.6 and 97.2 mM) produced a slight decrease in PTD that was significantly less than that observed in normocalcic and hypocalcic mediums. 5. In hypocalcic medium (1.1 mM) verapamil plus ethanol (48.6 and 97.2 mM) produced a decrease in PTD that was of the same relative magnitude (%) as that observed in normocalcic medium. However no potentiation of the combined effects of verapamil plus ethanol was observed in hypocalcic medium.     

Small intestinal perforation following minor trauma.

Small intestinal perforation occurred in two patients aged 70 years and 88 years who had experienced minor trauma by tripping or falling on the pavement. They both developed signs of generalized peritonitis and at laparotomy were found to have perforated the mid ileum. There was no sign of direct abdominal trauma but they had suffered minor facial trauma as a result of the fall.     

Physiopathology of venous stasis at the microcirculation level]

The division of the venous circulation in to two sectors, one constituted by the superficial and deep venous trunks (macrocirculation) and the other by the capillaries and precapillary venules (microcirculation), is surely schematical but aids the comprehension of many hemodynamic effects connected to hampered venous return and to the incompetence of the valvular devices. In fact many of the effects of stasis and venous hypertension (oedema, red cell diapedesis, skin dystrophies) cannot be explained merely by hydraulic mechanisms but require a primary alteration of the microvascular wall associated with structural changes of the perivascular connective tissue. The alterations that occur in microcirculation are of the utmost importance in the formation of the venules ulcerations. The passage of fibrinogen through large pores in the venules of the patients affected by venous hypertension derived from venous insufficiency creates a pericapillary fibrin deposition that cannot be removed because of inadequate blood and tissue fibrinolysis. This accumulation acts as a barrier to the diffusion of oxygen and other nutrients, determining a stasis dermatitis that may lead to tissue necrosis and ulceration. The more precise knowledge of the phenomena connected with the venous stasis at the level of microcirculation (pericapillary fibrin deposition, endothelial ischemia, blocked lymphatic drainage) will not only allow a deeper comprehension of the clinical signs but hopefully will lead to a more effective treatment of the postphlebitic syndrome.