Showing papers by "Jens Peter Bonde published in 1996"

Identifying environmental risk tomale reproductive function byoccupational sperm studies: logistics anddesign options

Abstract: ofthemalereproductive sys- temmightbeasensitive markerofenvi- ronmental hazards, theeffects ofwhich may extendbeyondreproductive func- tion. Thetestis ismorevulnerable toheat andionising radiation thanany other organofthebodyandseveral xenobiotics areknownto disrupt spermatogenesis after lowlevel exposure. Studies ofenvi- ronmental impacton human healthare oftenmost informative and accurate whencarried outintheworkplace where exposures canbehighandeasytodocu- ment.Semenanalysis provides readily obtainable information on testicular function. Themainadvantages incom- parison withfunctional measuressuchas fertility ratesandtimetakentoconceive arethepossibilities toexaminemen inde- pendently ofmarriage andpregnancy, to findchangesoffecundity withdifferent exposures within thesamepersonandto detect adverse effects whennoalteration offertility isyettakingplace. In the implementation ofanoccupational sperm studyconsiderable attention mustbepaid tologistic issues. A mobilelaboratory unitforinitial semenpreparation and processing may in some situations increase workercompliance andthequal- ityofspermcell motility. Thecrosssec- tionaldesignwhichhasbeenusedin

Identifying environmental risk to male reproductive function by occupational sperm studies: logistics and design options.

Abstract: Malfunction of the male reproductive system might be a sensitive marker of environmental hazards, the effects of which may extend beyond reproductive function. The testis is more vulnerable to heat and ionising radiation than any other organ of the body and several xenobiotics are known to disrupt spermatogenesis after low level exposure. Studies of environmental impact on human health are often most informative and accurate when carried out in the workplace where exposures can be high and easy to document. Semen analysis provides readily obtainable information on testicular function. The main advantages in comparison with functional measures such as fertility rates and time taken to conceive are the possibilities to examine men independently of marriage and pregnancy, to find changes of fecundity with different exposures within the same person and to detect adverse effects when no alteration of fertility is yet taking place. In the implementation of an occupational sperm study considerable attention must be paid to logistic issues. A mobile laboratory unit for initial semen preparation and processing may in some situations increase worker compliance and the quality of sperm cell motility. The cross sectional design which has been used in almost all male reproductive studies so far has several severe limitations including selection bias because of differential participation, difficulties in defining a suitable reference group, and lack of information about the time dimension of the cause-effect relation. The longitudinal design deals adequately with most of these constraints. Semen samples are collected before, during, and possibly after exposure to the risk factor of interest and causal inferences are based upon change of semen variables within a man over time rather than upon differences between men. The logistics of the longitudinal study may benefit from pre-employment health examinations to enrol newly hired workers and require fewer participants to obtain comparable statistical power. In conclusion, andrological methods and epidemiological designs are available for the implementation of valid studies concerned with environmental impact on human testicular function. Occupational sperm studies should probably not be the first choice when the objective is initial screening of environmental impact on fertility but should be implemented when their is a need to corroborate or refuse earlier evidence that specific exposures have impact on testicular function.

Communication Concerning the Risks of Occupational Exposures in Pregnancy

Abstract: The health professional who is involved in communicating information about reproductive risks from occupational hazards needs to consider several important aspects. Uncertainties in risk assessmenl, timing of exposure in relation to pregnancy, and the consequences of different preventive measures for the woman (family), as well as for the employer and other persons at the workplace are examples of such aspects. The basis for the pregnant woman's perception of risk must be recognized. The risk-communication goal is that the persons concerned fully understand the risk and its possible consequences, so that they win be able make informed decisions about how to act. More attention should be given to risk communication in the training of health professionals.

[Invasive ventilation. Classification, technique and clinical experiences with BiPAP/APRV (Biphasic Positive Airway Pressure/Airway Pressure Release Ventilation)].

Abstract: BiPAP (bilevel or biphasic positive airway pressure) and APRV (airway pressure release ventilation) are new, and from a technical viewpoint closely related techniques recently introduced to the field of invasive ventilatory support. BiPAP/APRV can be described as a pressure controlled continuous high flow positive airway pressure system with a time-cycled change between a high inspiratory pressure level and a lower expiratory pressure level. Due to highly sensitive valves placed in the inspiratory and expiratory part of the system, unrestricted spontaneous breathing is possible at any moment of the mechanically supported ventilatory cycle. During invasive ventilation BiPAP offers potential advantages by allowing unrestricted spontaneous breathing thus reducing the need for sedation and facilitating weaning. APRV has primarily been investigated in conditions of moderate to severe acute lung injury and it seems that APRV is associated with less detrimental effects on the cardiopulmonary system compared to conventional ventilatory strategies. Apart from a review of the literature the article gives a classification and a technical description of the systems and focuses on the practical approach to BiPAP/APRV, e.g. the initiation and adjustment of respiratory support and the weaning from ventilatory support when applying these techniques.