Long-term mechanical circulatory support system reliability recommendation: American Society for Artificial Internal Organs and Society of Thoracic Surgeons: long-term mechanical circulatory support system reliability recommendation.

Jointly developed by members of the American Society for Artificial Internal Organs and the Society of Thoracic Surgeons along with staff from the Food and Drug Administration, the National Heart, Lung and Blood Institute and other experts, this recommendation describes the reliability considerations and goals for Investigational Device Exemption and Premarket Approval submissions for long-term, mechanical circulatory support systems. The recommendation includes a definition of system failure, a discussion of an appropriate reliability model, a suggested in vitro reliability test plan, reliability considerations for animal implantation tests, in vitro and animal in vivo performance goals, the qualification of design changes during the Investigational Device Exemption clinical trial, the development of a Failure Modes Effects and Criticality Analysis, and the reliability information for surgeons and patient candidates. The document will be periodically reviewed to assess its timeliness and appropriateness within five years.

Long-term mechanical circulatory support system reliability recommendation: American Society for Artificial Internal Organs and The Society of Thoracic Surgeons: long-term mechanical circulatory support system reliability recommendation.

Jointly developed by members of the American Society for Artificial Internal Organs and the Society of Thoracic Surgeons along with staff from the Food and Drug Administration, the National Heart, Lung and Blood Institute and other experts, this recommendation describes the reliability considerations and goals for Investigational Device Exemption and Premarket Approval submissions for long-term, mechanical circulatory support systems. The recommendation includes a definition of system failure, a discussion of an appropriate reliability model, a suggested in vitro reliability test plan, reliability considerations for animal implantation tests, in vitro and animal in vivo performance goals, the qualification of design changes during the Investigational Device Exemption clinical trial, the development of a Failure Modes Effects and Criticality Analysis, and the reliability information for surgeons and patient candidates. The document will be periodically reviewed to assess its timeliness and appropriateness within five years.

A survey on hypersensitivity reactions in hemodialysis.

This survey was conducted from 1982 through 1984 by a cooperative effort among the Health Industries Manufacturers Association, seven dialyzer manufacturers, and the Food and Drug Administration. This article presents an analysis of the 1982-83 survey data and a summary of the 1984 data. Most of the reactions reported (99%) were associated with hollow-fiber dialyzers. About 50% of these reactions were experienced by patients using a dialyzer model for the first time, and greater than 98% of the reactions were related to new (unused) dialyzers. On average, there were 180 reactions reported per year, with greater than 90% being considered severe, including death, by the reporting center. A plot of the number of reactions versus time from 1982 through 1984 shows periods of 12-15 months in which the reaction rate remained practically constant. During these periods, the rate of reported reactions alternated from 60 to 150% of the average. Analysis of the survey data showed a strong correlation of the number of reactions with the race and age of the patients. Blacks and other minorities experience nearly three times as many reactions as white patients. Also, patients under 29 years of age seem to have nearly twice as many reactions as patients in the 30- to 49-year-old range, whereas patients over 50 years old have nearly half the number of reactions of the 30- to 49-year-old range. The average reactivity of the U.S. hemodialysis patient population was calculated to be 3.3 reactions per year per 1,000 patients exposed to hollow-fiber dialyzers and 0.3 reaction per year per 1,000 patients exposed to flat-plate dialyzers.(ABSTRACT TRUNCATED AT 250 WORDS)

Evaluation of membranes for plasmapheresis.

Commercial flat-sheet microporous membranes were evaluated for potential use in plasmapheresis with a specially designed filtration module. Significant differences in filtration rates were observed with different membranes. Saline filtration data were not useful in predicting the capacity of the membranes to filter plasma from whole blood. For all membranes studied, no rejection of plasma proteins was detected. No activation or deactivation of clotting factors was detected as a result of filtration. In addition, little or no hemolysis was caused by filtration with the various membranes. Saline, cell-free plasma, platelet-poor plasma, and whole blood were perfused over a track-etched membrane and the resulting filtration rates were compared. The cell-free plasma filtration rate decreased significantly with time, probably owing primarily to protein adsorption in the membrane pores. Cell-free plasma and saline filtration data were used to calculate an apparent adsorbed layer thickness in the membrane pores. Perfusion of platelet-poor plasma and whole blood resulted in time-dependent filtration rates that were much lower than those obtained when cell-free plasma was perfused. Results of the study support recent theoretical models that postulate that the rate-limiting process for blood filtration is the formation of a layer of blood cells (particle polarization) on the membrane surface.

Effect of histamine and methacholine on nasal airway resistance in atopic and nonatopic subjects. Comparison with bronchial challenge and skin test responses.

Serial nasal, intracutaneous, or bronchial challenges were carried out with solutions containing 2- or 3-fold increments in histamine (H) or methacholine (Meth) concentration until nasal airway resistance (NAR) increased by more than 100%, a large intracutaneous reaction was elicited, or FEV1 decreased by 20% or more. Thirty nonatopic and 48 asymptomatic atopic subjects were studied, the latter group divided into rhinitic patients with and without asthma. Several types of data analysis demonstrated there was no significant difference in the nasal or cutaneous effects of H or Meth between the atopic and nonatopic groups. Comparable results were obtained in a subgroup of 39 subjects (13 normal, 13 atopic, and 13 atopic with asthma) who underwent all six test sequences (i.e., nasal, cutaneous, and bronchial with both drugs). As expected, the asthmatics showed significantly increased bronchial reactivity to both agents. In comparison with Meth, H had a much greater effect on the nasal mucosa and skin than on the bronchi. It is concluded that, contrary to bronchial responses, but in accord with cutaneous reactivity, the nasal responses of nonatopic subjects, atopic persons with allergic rhinitis alone, and subjects with both allergic rhinitis and asthma show no intergroup differences on testing with H or Meth.

The effects of topical saline and isoproterenol on nasal airway resistance.

Following determination of baseline nasal airway resistance (NAR) in human subjects, phosphate-buffered saline (PBS) was aerosolized into each nostril and NAR measurements repeated 8 times in 15 minutes. The mean maximal NAR increase in 102 subjects was 22.5% (SD +/- 24.5%) with no significant difference between atopic and nonatopic persons. Hay fever patients did not show significantly increased responsiveness to PBS while symptomatic. During 242 repeat challenges with PBS in 67 asymptomatic subjects, NAR increased over 50% in 24 tests. Following a series of 6 PBS challenges at 15-minute intervals, 10 of 71 subjects had more than a 100% increase in NAR over initial baseline values. Administration of PBS on cotton pledgets, pipetting PBS into the nose, or even just inserting a nasal speculum produced greater increases in NAR than the usual aerosol method. Intranasal atropine effectively blocked PBS-induced increases in NAR, suggesting parasympathetic stimulation as a mechanism. Isoproterenol increased NAR over 100% in 27 of 53 subjects, with no significant difference among rhinitic, asthmatic, and nonatopic individuals. This effect was inhibited by propranolol. Isoproterenol administration to 12 ragweed-sensitive subjects 15 minutes prior to ragweed challenge produced a variable inhibition in NAR responses or no protection at all. Thus the direct effects of isoproterenol on the nasal vasculature tend to outweigh those expected from inhibition of mediator release under the conditions of this study.

An improved technique for nasal inhalation challenge tests.

An improved technique for nasal inhalation challenge tests is described. It includes an improved delivery system utilizing a Maxi-Myst air compressor delivering a flow of room air controlled by an in-line, electroncially timed solenoid which precisely controls the duration of compressor activity. A No. 251 DeVilbiss atomizer will deliver 0.1 + 0.01 gm/spray when the flow rate is 11.5 L/min, the duration of atomizer activity is approximately 0.1 sec, and the amount of liquid in the atomizer insert is kept between 0.75 and 2.0 ml. Nasal aerosol challenge of 0.1 ml of isotonic phosphate-buffered saline per nostril produced less variability in nasal airway resistance (NAR) response than 0.2 ml, and the smaller volume proved satisfactory for 6 consecutive saline challenges at 15-min intervals. A new face mask, which did not impinge on the bridge of the nose or paranasal structures, yielded lower baseline values of nasal airway resistance and much less variability in these measurements. Techniques employed in objectively quantitating nasal responses to various exogenous substances are briefly but critically reviewed.