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The effect of laparoscopic cholecystectomy on cardiovascular function and pulmonary gas exchange.
No full textHemodynamic changes, pulmonary CO2 elimination (VECO2) and gas exchange were evaluated during laparoscopic cholecystectomy. An algorithm to calculate inspired ventilation (VI) needed to maintain constant PaCO2 was also developed. In 12 ASA physical status I patients undergoing laparoscopic cholecystectomy, heart rate (HR), mean arterial pressure (MAP), cardiac index (CI), and systemic vascular resistance index (SVRI) were measured by the analysis of a radial artery pressure profile before, during, and after CO2 insufflation. Alveolar-arterial oxygen pressure gradient (P(A-a)O2), physiological and alveolar ventilatory dead space fractions (VDphys/VT; VDalv/VT), and PaCO2 were measured as well. VECO2 was assessed every minute in the patients maintained in the head-up position. HR did not significantly change during pneumoperitoneum, whereas MAP showed a transient increase (24.9\%; P < 0.05) after CO2 insufflation. CI remained stable during pneumoperitoneum, but increased (25.0\%; P < 0.05) after deflation. As a consequence, SVRI transiently increased after CO2 insufflation and decreased by 15.8\% (P < 0.05) 5 min after deflation. P(A-a)O2 increased slightly (P < 0.05) with increased anesthesia time. VDphys/VT and VDalv/VT did not change after pneumoperitoneum onset, but VDalv/VT decreased after CO2 deflation (13.4\%; P < 0.05). VECO2 increased (decreased) after a monoexponential time course during (after) CO2 insufflation in 8 of 12 patients. The mean time constants (t) of the monoexponential functions were 26.3 and 15.4 min during and after pneumoperitoneum. A monoexponential time course was shown also by PaCO2 during CO2 insufflation (tau = 27.8 min). Finally, the VI needed to maintain PaCO2 at a selected value could be calculated by the following algorithm: VI = [0.448.(1-e(-t/tau) + 2.52].(VA.PaCO2.713)-1, where VA corresponds to alveolar ventilation and t must be chosen according to the pneumoperitoneum phase. We conclude that CO2 insufflation in the abdominal cavity does not induce significant changes in cardiopulmonary function in ASA physical status I patients. The algorithm proposed seems to be a useful tool for the anesthesiologists to maintain constant PaCO2 during all surgical procedures
Artificial gravity as a tool to prevent cardiovascular deconditioning in Space. Cardio-circulatory responses to short-radius rotation and exercise in human centrifuge
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Observations of the pathologist on precancerous lesions of the larynx. Integrated with histological data and quantitative analysis of nuclear DNA content
No full textIt is the impression of pathologists that a multicentric origin of a dysplastic process in the larynx is not a rare event. The otologists suggest something more, to wit that the same factor which damages the laryngeal mucosa, thus giving rise occasionally to a carcinoma, damages other tissues as well, and not only tissues of the larynx: it attacks areas further down the respiratory tract, especially the bronchioles. Of 409 lung carcinomas studied at autopsy, 41 were associated with malignant tumors of other viscera. Undoubtedly, the larynx is the viscus which is the most frequently affected in this association. As regards the dysplasias, leukoplasias and the carcinomas in situ, the microinvasive cancers, and the cases of Bowen's disease are as sharply separated from the true carcinomas by some authors. The argument that cancers in situ are nonetheless cancers because statistical studies are in agreement in pointing out the course of the lesion towards an infiltrative carcinoma (even up to an interval of 5 to 10 yr). However, precisely here lies the importance in identifying these forms as early as possible; and then, a clinician, well convinced of what will follow, has sufficiently long time in which to interrupt a fatal course. Therefore, both groups of lesions should be evaluated in a single discussion: the precarcinomas and the early carcinomas on the one hand, because they still can be cured by not mutilating operations; and on the other hand the invasively growing carcinomas, which often need a total laryngectomy. Studies of Sirtovi (1963, 1964) and Kleinsasser (1964) which represent fundamental stages in this regard, are in accordance with these conclusions. Sirtovi is of the opinion that the major part of so-called relapses occur in the larynx, because in this region, more so than elsewhere, the carcinoma has a progressive character. Kleinsasser agrees with this statement and affirms that sooner or later a carcinoma in situ evolves towards a carcinoma in 90% of the cases
Effects of different after-loads and muscular lengths on maximal explosive power of the lower limbs.
No full textMaximal explosive power during two-leg jumps was measured on four sedentary subjects [mean age 43.0 (SD 10.3) years, mean height 1.74 (SD 0.04) m, mean body mass 73.5 (SD 1.3) kg] using a sledge apparatus with which both force and speed could be directly measured. Different after-loads were obtained by positioning the sledge at five different angles (SA, alpha) in respect to the horizontal so that m . g . sin alpha (where m is the sum of body mass and the mass of the sledge seat, g the acceleration due to gravity) decreased (on average) from 78% body mass at 30 degrees to 27% body mass at 10 degrees, thus simulating conditions of low gravity. The subjects were asked to jump maximally, without counter movement, starting from 70 degrees, 90 degrees, 110 degrees, and 140 degrees of knee angle (KA); the protocol being repeated at 10 degrees, 15 degrees, 20 degrees, 25 degrees and 30 degrees SA. The average ((W) over dot(mean)(+)) power output during concentric exercise (CE) was found to decrease when the starting KA was increased, but to be unaffected by SA (i.e. by the after-load, the simulated low g). The higher values of (W) over dot(mean)(+) were recorded at 90 degrees KA [15.01 (SD 1.46) W . kg(-1), average for all subjects at all SA]. The subjects were also asked to perform counter movement (CMJ) and rebound jumps (RE) at the same SA as for CE. In CMJ and RE maximal power outputs were also found to be unaffected by the SA; (W) over dot(mean)(+) amounted to 16.03 (SD 0.28) W . kg(-1) in CMJ and 16.88 (SD 0.36) W . kg(-1) in RE (average for all subjects at all SA). In CE, CMJ and RE, the instantaneous force at the onset of the positive speed phase (F-i) was found to increase linearly with SA (i.e. with increasing m . g . sin alpha), and the difference between F-i in CMJ or RE and F-i in CE (F-i in CMJ minus F-i in CE and F-i in RE minus F-i in CE) was unaffected by SA. This indicated that both maximal power and the elastic recoil were unaffected by simulated low g ranging from 1.71 m . s(-2) (at 10 degrees SA) to 4.91 m . s(-2) (at 30 degrees SA)
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