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Biomedical subjects

J F Ryan

Publications and source records attributed to J F Ryan.

At least 55 records · Page 3Linked to original sources
PubMed1983

Wasted ventilation measured in vitro with eight anesthetic circuits with and without inline humidification.

Compression of gases (Boyle's law) and circuit compliance are major determinants of anesthesia circuit function. The materials of which circuits are constructed and the use of heated humidifiers may result in clinically important variations in delivered minute ventilation (VE) secondary to variations in compression volume. We examined eight anesthetic circuits both with and without a heated humidifier in an in vitro setting. Compression volume was determined with a large calibrated syringe. Circuit efficiency was determined by measuring VE at multiple peak inflation pressures (PIP) while using a pediatric ventilator with fixed VE, respiratory rate, fresh gas flow, and I/E ratio. As expected, both compression volume and delivered VE highly correlated with the type of circuit and the pressure at which it was examined (P less than 0.001). Mapleson D circuits had the lowest compression volume and were the most efficient circuits (P less than 0.0001). Pediatric circle systems were intermediate and adult circle systems had the largest compression volume and were the least efficient. Humidifiers uniformly increased compression volume. The following conclusions were drawn: 1) the anesthetic circuit, its material, and the pressure at which it operates are important determinants of circuit function; 2) humidifiers increase compression volume; 3) Mapleson D circuits had the lowest compression volume and therefore were the most efficient; 4) highly compliant adult circuits may result in compression volume losses that exceed the tidal volume of a pediatric ventilator; 5) humidifiers with low volume and rigid tubing should have the least effect on minute ventilation; and 6) highly compliant adult circuits when used in the care of infants and small children must be used with caution.

Anesthesiology↗
PubMed1983

Life-threatening apnea in infants recovering from anesthesia.

To determine whether prematurely born infants with a history of idiopathic apneic episodes are more prone than other infants to life-threatening apnea during recovery from anesthesia, the authors prospectively studied 214 infants (173 full term, 41 premature) who received anesthesia. Fifteen premature infants had a preanesthetic history of idiopathic apnea. Six of these required mechanical ventilation because of idiopathic apneic episodes during emergence from anesthesia. Two were ventilated for other reasons, and seven recovered normally. Infants ventilated for apnea were younger (postnatal age 1.6 +/- 1.2 months, mean +/- SD; conceptual age 38.6 +/- 3.0 weeks) than those who recovered normally (postnatal age 5.6 +/- 2.7 months; conceptual age 55.1 +/- 11.3 weeks) (P less than 0.01). No other premature or full-term infant was ventilated because of postoperative apneic episodes. The authors conclude that anesthetics may unmask a defect in ventilatory control of prematurely born infants younger than 41-46 weeks conceptual age who have a preanesthetic history of idiopathic apnea.

Anesthesia↗
PubMed1983

Hematoma-induced febrile response in the pediatric patient.

Frequently there is a temperature elevation in children following operative procedures or trauma involving the long bones. A combined clinical and laboratory study investigated the possibility that this was secondary to blood resorption. A clinical study was conducted by reviewing the records of all children admitted to the hospital over a 10-year period with closed femoral or tibial fractures. All these patients demonstrated a temperature elevation to at least 101 degrees F. In the laboratory study, rabbits of different ages were bled, and this blood was reinjected into their quadriceps muscle to create hematomas. Control rabbits were hemorrhaged and either were not reinjected with their blood or were injected intramuscularly with lactated Ringer's solution. Those rabbits that received the intramuscular blood injections developed significant temperature elevations, and the younger the rabbit the more pronounced the temperature rise.

Adolescent↗
PubMed1975

Percutaneous catheterization of the radial artery in the critically ill neonate.

Percutaneous catheterization of the radial artery appears to be a simple and safe alternative to catheterization of the umbilical artery for monitoring critically ill neonates. This avoids the serious and potentially fatal complications associated with use of the umbilical arterial catheter, and it is also applicable to monitoring of neonates in whom the umbilical artery is no longer patent. We observed no serious sequelae in cannulation of the radial artery and think that the technique should be used more widely.

Arm↗
PubMed1975

A modified procedure for the determination of nitrate in sediments and some natural waters.

This paper describes a modified procedure for the determination of nitrate in sediments and some natural water samples. In the Water Quality Branch Laboratories where large numbers of samples are regularly analysed, it was found that existing methods1,4 do not give precise and accurate results particularly when applied to sediment samples and some natural waters. The reasons for such inaccuracies have sebsequently been found and a method for removal of such interfering substances have been devised. The proposed method essentially consist of two steps. In the first step the interfering substances such as sulfide and humic acid substances are removed by precipitation with copper. The resultant solution is then analysed by a colorimetric approach utilizing cadmium fillings as the reducing agent to reduce nitrate to nitrite, and analyse the resultant nitrite with sulfanilamide, and naphtylene diamine. The smallest amount of nitrate that can be detected with certainty is approximately 10 mug-at N/Kg and 50 mug/ at N/Kg in water and sediments respectively. The figures for sediments are based on dissolving 20 gms. of sediment, dry weight, in 100 ml volume. The proposed method has been tested on a wide variety of natural water samples, sediments, clays and sands.

Chemical Precipitation↗
PubMed1975

Re-evaluation of dosage and duration of action of d-tubocurarine in the pediatric age group.

A cumulative dose-response curve for d-tubocurarine based on body weight was determined for 44 infants and children 1 day to 7 years of age during halothane, nitrous oxide and oxygen anesthesia. Depression of thumb adduction was measured. Age difference did not affect the mean dose-effect response. Infants less than 10 days old, however, showed the wideest deviation of responses. When the effect of d-tubocurarine is determined by twitch response, infants and children are more resistant to d-tubocurarine and recover faster than adults from similar levels of neuromuscular depression. Monitoring of neuromuscular function by train-of-four stimulation proved as useful as it is in adults.

Age Factors↗