Cardiorespiratory stability of premature boys and girls during kangaroo care.

The objective of the investigation was to study the stability of the cardiorespiratory system of 20 premature boys and girls during maternal kangaroo care (KC) and in the incubator. Stability of heart rate, respiration and oxygen saturation was compared in a pretest-test-posttest design by means of a stability score. The three stability items and the total stability did not change significantly during the three conditions. In some individuals the stability either increased or decreased markedly during Kangaroo Care. The boys showed significantly less cardiorespiratory stability both during kangaroo care and in the incubator compared to the girls.

Pitfalls in respiratory monitoring of premature infants during kangaroo care.

The reliability of respiratory monitoring, using either chest or back electrodes, was studied in 13 preterm infants during kangaroo care (infant-parent skin to skin contact). In three out of four infants with chest electrodes both infant and parental respiration were clearly visible on pneumograms. In these infants apnoeic pauses were not registered because parental respiration was recorded as infant breathing. Bradycardia and oxygen saturation were, however, properly registered. In infants with electrodes placed on the back infant respiration was less superimposed by parental breathing. However, even in some of these infants parental respiration was visible in the pneumograms. It is concluded that during kangaroo care the electrodes should be placed on the back and monitoring should always include heart rate and oxygen saturation.

Determination of root exudates in a steril continuous flow culture. I. The culture method.

A sterile plant culture consisting of culture vessels, culture solution container, collecting flasks for percolating nutrient solution, illumination and aeration systems and a suitable pump is described. Its difference with other culture methods is a very slow, continuous percolation of the nutrient solution through the rooting medium. Well defined and controllable conditions can thus be established in the rhizosphere over long culture periods. Samples can be collected at short intervals without disturbing the rhizosphere in any way nor endangering the sterility of the culture. One of the fundamental factors determining the special ecological characteristics of the plant rhizosphere is the liberation of organic and inorganic substances by the plant root. During the study of this phenomenon it became evident that the amount of substances liberated varies within wide limits (factors 100 to 1000) according to the conditions in which the root is developing.

Determination of Root Exudates in a Steril Continuous Flow Culture. II. Short-Term and Long-Term Variations of Exudation Intensity.

The exudate production of alfalfa under the conditions of the sterile flow culture was quantitatively measured. In the first 40 days 3.10(-3) mumoles amino-N, 2.5 muequivalents of organic acids and approximately 10(-4) mumoles of reducing sugars were liberated per plant and per day into the percolating nutrient solution. The amino acid concentration in the outflow varies according to a daily periodicity. The exudation of a colored substance also shows daily periodical variations. This pattern is different from the pattern of the amino acid exudation, however, and directly coupled to shoot illumination. Short-term 2,4-dinitrophenol additions to the nutrient lower the liberation of amino acids into the percolating solution.