Incubator Humidity Research Articles

Influence of incubator humidity on sleep and behaviour of neonates kept at stable body temperature.

The influence of incubator air humidity (via passive humidification through use of a water reservoir or via active humidification to 2 and 4 kPa) on sleep and behavioural changes was investigated in 13 neonates. The thermal environment of the incubator was servocontrolled via an interactive device tracking the skin temperature changes of the neonates. Using this servocontrolled skin temperature derivative heating programme, it is believed that an increase in air moisture content (reducing evaporative skin cooling) can be counterbalanced by a fall in neutral air temperature, so as to keep the body thermally constant. This procedure permits the experimental evaluation of the specific effect of air humidity on the thermal equilibrium air temperature and the thermal comfort of neonates without eliciting thermoregulatory mechanisms. Under the experimental conditions, in order to keep body temperature stable an increase in water vapour partial pressure from 1.72 (water reservoir) to 3.99 kPa (produced by a nebulizer) is counterbalanced by a decrease in air temperature of 1.49 degrees C. Within this humidity range, the air temperature must be lowered by 0.05 degrees C when the vapour pressure is increased by 0.08 kPa. The magnitude of this deviation depends on the humidity range and is probably a result of changes in the wetted skin area. When body temperature is kept constant, changes in air humidity do not modify sleep, body motility and respiratory and heart rates in neonates.

Influence of incubator humidity on sleep and behaviour of neonates kept at stable body temperature

The influence of incubator air humidity (via passive humidification through use of a water reservoir or via active humidification to 2 and 4 kPa) on sleep and behavioural changes was investigated in 13 neonates. The thermal environment of the incubator was servocontrolled via an interactive device tracking the skin temperature changes of the neonates. Using this servocontrolled skin temperature derivative heating programme, it is believed that an increase in air moisture content (reducing evaporative skin cooling) can be counterbalanced by a fall in neutral air temperature, so as to keep the body thermally constant. This procedure permits the experimental evaluation of the specific effect of air humidity on the thermal equilibrium air temperature and the thermal comfort of neonates without eliciting thermoregulatory mechanisms. Under the experimental conditions, in order to keep body temperature stable an increase in water vapour partial pressure from 1.72 (water reservoir) to 3.99 kPa (produced by a nebulizer) is counterbalanced by a decrease in air temperature of 1.49°C. Within this humidity range, the air temperature must be lowered by 0.05°C when the vapour pressure is increased by 0.08 kPa. The magnitude of this deviation depends on the humidity range and is probably a result of changes in the wetted skin area. Conclusion: When body temperature is kept constant, changes in air humidity do not modify sleep, body motility and respiratory and heart rates in neonates.

Dynamic programming approach for newborn's incubator humidity control

The anatomy, physiology, and biochemistry of the human skin have been studied for a long time. A special interest has been shown in the water permeability of the premature infant's skin, which is known to be an important factor in the maintenance of a controlled water and heat balance. The rate of evaporative heat exchange between the skin surface of a very premature infant and the surrounding incubator air may be so high that evaporative heat loss alone may exceed the infant's total metabolic heat production. However, it has been demonstrated in several investigations published in recent years that basal evaporative water loss can be consistently reduced by increasing the ambient humidity. Nevertheless, the passive humidification system (water reservoir) used in most incubators cannot achieve high and steady humidity levels. In this paper, we propose an active humidification system. The algorithm is based on a combination of optimal control theory and dynamic programming approach. The relative-humidity (R.H.) regulation is performed in range of 35-90% at 33 degrees C with small oscillations (+/- 0.5% R.H.) around the reference value (i.e., prescribed R.H.).

Eggshell Conductance and Other Functional Qualities of Ostrich Eggs

Eggshell conductance was measured and eggshell conductance constants were calculated for eggs from ostriches. In addition, egg water, yolk, albumen, shell, and total solids were measured in an effort to determine the maternal investment of ostrich eggs. The results of the study suggest that the optimal incubator humidity for ostrich eggs is less than 25% to allow a 15% loss of initial egg mass during the 45-d incubation period. This low humidity does not preclude increasing humidity during the actual hatching process. In addition, incubation temperatures need to be adjusted to allow a longer development time for the embryo to attain an adequate level of maturity to survive the plateau stage in oxygen consumption or to prevent the use of limited energy of the yolk to survive the anoxia of tucking and internal pipping. The optimal incubation temperature of ostrich eggs appears to be between 36.1 and 36.9 C.

Postmortem Findings of Ostriches Submitted to the Oklahoma Animal Disease Diagnostic Laboratory

A review of 121 ostrich necropsies from the files at the Oklahoma Animal Disease Diagnostic Laboratory was conducted. The birds ranged in age from unhatched embryos to 4 years; the majority were less than 3 weeks old. The most common cause of death was ostrich chick fading syndrome (OCFS). OCFS is characterized by depression, anorexia, and death 3-5 days after onset of clinical signs in ostriches less than 3 weeks old. Escherichia coli and/or Klebsiella pneumoniae were isolated from various organs in these cases, and mortality ranged from 40% to 100%. Other conditions observed were edema in chicks associated with high incubator humidity levels, aspergillosis, leg deformities, and impaction of the proventriculus.

Improving turkey poult quality by correcting incubator humidity to match eggshell conductance.

One of the most important factors determining hatchability of avian eggs is their proper water budget during incubation. We show here that water budget changes of turkey eggs effect not only hatchability but also poult quality. In addition to an increase in hatchability of 3.3%, poult quality was increased by 7.3%. This was achieved by sorting eggs into low (less than 18.5), medium (18.5 to 22.0) and high (greater than 22.0) eggshell mass-specific water vapour, conductance categories and incubating them in matching incubation humidities of 21.8, 26.6 and 31.4 Torr, corresponding to relative humidities of 45, 55 and 65% at 37.5 degrees C, respectively. A total diffusive water loss of 11.5% (range 10 to 14%) of the initial egg mass in 25 d of incubation yielded maximal hatchability and poult quality.

Humidification of incubators.

The effect of increasing the humidity in incubators was examined in 62 infants of less than 30 weeks' gestation. Thirty three infants nursed in high humidity for two weeks were compared retrospectively with 29 infants from an earlier study who were nursed under plastic bubble blankets or with topical paraffin but without raised humidity. Humidification reduced skin water loss and improved maintenance of body temperature from birth, but did not delay the normal postnatal maturation of the skin. Infants nursed without humidity frequently became hypothermic in spite of a high incubator air temperature. These advantages must be weighed against the finding that overheating was more common and Pseudomonas was more commonly isolated from the infants. It is recommended that incubator humidity is raised for babies under 30 weeks' gestation in the first days of life but meticulous attention should be paid to fluid balance, avoiding overheating, and cleansing of the humidifier reservoir.

Increasing Hatchability of Turkey Eggs by Matching Incubator Humidity to Shell Conductance of Individual Eggs

One of the most important factors determining hatchability of avian eggs is the proper water balance of the eggs during incubation. In turkey eggs, a total diffusive water loss (F) of 12 ± 1 %SD initial egg mass in 28 days, yielded maximal hatchability irrespective of the combination of eggshell water vapor conductance (G) and incubator humidity (PI), which brought about this water loss. A good correlation was found between G as obtained at the beginning of incubation and the final F in a given PI. The G in a random sample of 1256 fresh turkey eggs was normally distributed around the mean of 18.70 ± 2.87 SD milligrams (100 g·day·torr)−1 (Coefficient of variation = 15.3%). The distribution of G in eggs with dead in the shell embryos had, in addition, two more peaks of G values [around 22.5 and 13.0 mg (100 g·day·torr)−1 ]. When eggs were sorted into low (<17), medium (17 to 20), and high (>20) G categories, and incubated at low (19.4), medium (26.6), and high (33.9) torr PI, respectively, hatchability increased by a factor of 1.08. Poor hatchabilities were obtained in mismatching humidities and conductances. It seems that hatchability success may be experimentally improved if a correct rate of water loss is fitted to sorted eggs during incubation.

1322 INCUBATOR HUMIDITY WITH DIFFERENT HUMIDITY RESERVOIR BAFFLE SYSTEMS

Although important in reducing heat and water losses from newborns, incubator humidities are difficult to predict and control. A removable metal baffle for use in an incubator humidity reservoir has been recently modified by one manufacturer and contributes to this unpredictability. Using an electric hydrometer, the relative humidities (R.H.) of 7 Air-Shields incubators were measured 1) with no baffle in the humidity reservoir, 2) with the manufacturer's older and larger iron baffle and 3) with a recently introduced smaller steel “W” shaped baffle. Incubator temps. were servo controlled to 34°C, and full humidity reservoirs were opened to maximum settings.Both baffles increase incubator humidity, but the variability was greater with the smaller steel baffles, and the 3.7% increase with this steel baffle is significantly less (p<0.01) than the 14.1% increase with the larger iron baffle. Since this observation, excess heat and water losses from newborns have been corrected by replacing the newer and smaller baffles with the larger iron baffles. This experience reinforces the opinion that incubators must not only be designed and modified carefully, but also used knowledgeably.