Gorlin's formula vs intraoperative measurement of the orifice area in mitral valve stenosis.

Table 1-Effects of lsoproterenol and VIP on Histamine-induced Bronchoconstriction HISTT Subject HISTt HIST HISTt HIST+ISO (28 p.g) HISTt HIST+ISO (375 sg) HISTt HIST+ VIP (375 g) *Mean ± SE (n) from all controlhistamine challenges. tData calculated from Figure 1. First value is response to first histamine challenge and second value is response to second histamine challenge conducted 5 h later, immediately after vehicle administration or pretreatment with isoproterenol or VIP. Cumu1ative dose units of histamine (sum of histamine concentration in mg/ml x number ofbreaths taken) that decreased FEy1 by 20%. Abbreviations: HIST = histamine; ISO isoproterenol; VIP = vasoactive intestinal peptide. when injected intravenously into an intact cat preparation,' indicating that VIP had not adhered to the plastic surfaces ofthe nebulizer in sufficient amounts to lower its biological efficacy. The lack ofeffectiveness ofaerosolized VIP may result from rapid metabolic inactivation or from avid binding to mucus layer proteins; alternatively, because ofits molecular size or configuration, VIP may be denied access to airway smooth muscle cells when administered topically. In isolated human airways, VIP has been reported to have only weak relaxant actions4 which may provide the most plausible explanation fbr its ineffectiveness in the present study. Regardless of the cause, the present results demonstrate that aerosolized VIP, at a dose previously shown to protect against histamine-induced bron-choconstriction in dogs, fails to protect against histamine-induced bronchoconstriction in human subjects. Since completion ofthis study, another report has been published demonstrating the lack ofeffectiveness ofaerosolized VIP in protecting against exercise-induced bronchoconstriction in asthmatics (Bundgaard A, Enehjelm SD, AA gestrup S. Pretreatment of exercise induced asthma with inhaled vasoactive intestinal peptide [VIP]. Gillespie MN, Altiere RJ. In vivo broncho-dilator aetivityofvasoactive intestinal peptide. effect ofVIP in vivo: protection against bronchoconstriction induced by histamine or PGFF. In: Said SI, ed Vasoactive intestinal peptide. of bronchial inhalation challenge procedures. muscle: in vitro studies. I readwith interest the article by Evoraetal(Chestl983; 84:180) in which they conclude that intraoperative measurement ofthe mitral valve area with a Foley balloon is simple, safe and reliable, but the results obtained are greater than the values calculated by Gorlin's formulL I think there are two possibilities for the systematic differences observed: 1) the circular form of the Foley balloon (direct measurement) is changed to an elliptic form with a smaller diameter (probably similar to the results obtained by Gorlin's formula), because the balloon ofthe Foley catheteris compressed bythe mitral valve; 2) the Foley …