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Biomedical subjects

Y Y Phillips

Publications and source records attributed to Y Y Phillips.

52 records · Page 3Linked to original sources
PubMed1989

A steady state method of measuring carbon monoxide diffusing capacity of the lung of sheep.

A method for measuring the diffusing capacity of the lung for carbon monoxide (DLCO) in sheep was developed. The test's usefulness and reliability was studied in ten, splenectomized adult ewes. Hemoglobin concentration and weight were found to affect sheep DLCO. This article describes a method of determining DLCO in sheep, gives preliminary results of limited testing, and discusses factors affecting DLCO in sheep.

Animals↗
PubMed1988

Computer modeling of thoracic response to blast.

Primary blast injury affects the gas-containing structures of the body. Damage to the lungs with resultant respiratory insufficiency and arterial embolization of air from alveolar pulmonary venous fistulae is the predominant cause of morbidity and mortality following high-level blast exposure. In an effort to generate a widely applicable damage-risk criterion for thoracic injury from blast we are developing a complex computer finite element model (FEM) of the thorax. Taking an engineering approach, a horizontal cross-section of the thorax is divided into small discrete units (finite elements) of homogeneous structure. The necessary physical properties (density, bulk modulus, etc.) are then determined for each element. Specifying the material constants and geometry of the elements, the computer can load the surface of the structure with some force-time function (blast pressure-time history) and calculate the resultant physical events such as displacement, compression, stress, strain, etc. Computer predictions of pressure wave phenomena in the lung parenchyma are compared with trans-bronchially measured pressures in blast-exposed animals. The model should prove useful in assessing the risk of blast injury in diverse overpressure environments and may give insight into pathophysiologic mechanisms and strategies for protection.

Animals↗
PubMed1988

Cloth ballistic vest alters response to blast.

Ballistic wounds have been and will remain the principal cause of casualties in combat. Cloth ballistic vests (CBV) play an important role in limiting critical wounds from fragments and small-arms fire. There is an increased risk of primary blast injury on the modern battlefield. In a previous study, volunteers were exposed to short-duration blast waves of low peak pressure (18.6 +/- 0.8 kPa). Pressure measurements made in the distal esophagus as an estimate of intrathoracic pressure (ITP) were significantly higher (p less than 0.05) when the standard U.S. Army ballistic jacket was worn (8.7 +/- 1.2 kPa) than when fatigues alone were worn (7.4 +/- 0.7 kPa). In this study 58 sheep were exposed to nominal blast levels of 115, 230, 295, and 420 kPa peak pressure in groups of 12, 18, 16, and 12, respectively. Half of each group was fitted with a CBV. Lung weight index (LWI), lung weight expressed as a percentage of body weight, was used as a measure of blast injury. Use of the CBV was associated with a significant increase in LWI (p less than 0.05) which averaged 21% for the two middle exposure groups. At the 420 kPa level, two of six non-CBV animals died as opposed to five of six animals wearing the CBV. Intrathoracic pressure was generally higher in the CBV group. Likely mechanisms of injury enhancement include an increase in target surface area and an alteration of the effective loading function on the thorax. This information may be useful in the triage and treatment of casualties exposed to intense blast environments.

Animals↗
PubMed1988

Effect of exercise in sheep on the absorption of intramuscular atropine sulfate.

In normal female sheep, we investigated effects of exercise on the absorption of atropine sulfate (0.02 mg/kg) given intramuscularly. The exercise regime consisted of treadmill running (20 min at 3-4 mph at 0 degrees grade) starting immediately after intramuscular atropine injection into the biceps femoris. Six normal female sheep received intramuscular atropine and 7-14 days later an identical intramuscular dose of atropine with exercise. Serum levels of atropine measured by radioimmunoassay were monitored over a 6-hour period. The time to peak concentration was significantly less with exercise than without, 2.9 +/- 2.1 and 13.7 +/- 5.4 min, respectively (p less than 0.005). In addition, peak serum atropine concentrations tended to be higher, 9.7 +/- 1.3 ng/ml with exercise versus 7.1 +/- 2.9 ng/ml without exercise; however, the difference did not attain statistical significance (p less than 0.08). This study demonstrates that exercise increases the early absorption of intramuscularly administered atropine sulfate.

Absorption↗
PubMed1988

Cardiopulmonary effects of nalbuphine hydrochloride and butorphanol tartrate in sheep.

The cardiopulmonary, sedative and analgesic effects of butorphanol tartrate and nalbuphine hydrochloride were evaluated in six adult crossbred Dorset sheep (Ovis aries). The animals were divided randomly into two groups of three. The first group received butorphanol tartrate (0.5mg/Kg s.c.) followed in 3 days by nalbuphine hydrochloride (1 mg/Kg, s.c.). The second group received nalbuphine followed in 3 days by butorphanol. Cardiopulmonary parameters were evaluated at baseline (once the animal had accommodated to restraint); immediately following analgesic administration; and at 15, 30, 60, 90 and 120 minutes after analgesic administration. No significant changes (alpha greater than .05) from baseline were seen in any of the measured cardiopulmonary parameters from either the butorphanol or nalbuphine groups. Butorphanol produced the most dramatic analgesic and sedative effects with onset of both within 15 minutes of administration and peak effects occurring 30 minutes post injection. The degree of analgesia was diminished at 120 minutes while the sedative effect returned to near baseline by 90 minutes. The nalbuphine group also showed an onset of analgesia 15 minutes post injection reaching a peak effect after 30 minutes. However, onset of sedation occurred 30 minutes post injection achieving a peak effect at 60 minutes which was markedly less than that of butorphanol. As in the butorphanol group, analgesia was diminished at 120 minutes.

Analgesia↗
PubMed1986

Primary blast injuries.

Injury from explosion may be due to the direct cussive effect of the blast wave (primary), being struck by material propelled by the blast (secondary), to whole-body displacement and impact (tertiary), or to miscellaneous effects from burns, toxic acids, and so on. Severe primary blast injury is most likely to be seen in military operations but can occur in civilian industrial accidents or terrorist actions. Damage is seen almost exclusively in air-containing organs--the lungs, the gastrointestinal tract, and the auditory system. Pulmonary injury is characterized by pneumothorax, parenchymal hemorrhage, and alveolar rupture. The last is responsible for the arterial air embolism that is the principle cause of early mortality. Treatment for blast injury is similar to that for blunt trauma. The sequalae of air embolization to the cerebral or coronary circulation may be altered by immediate hyperbaric therapy. Use of positive pressure ventilatory systems should be closely monitored as they may increase the risk of air embolism in pneumothorax. Morbidity and mortality may be increased by strenuous exertion after injury and by the wearing of a cloth ballistic vest at the time of the blast.

Blast Injuries↗
PubMed1986

Long-acting intramuscular anesthetic regimen for swine.

A two-stage, long-acting, injectable anesthetic regimen which provided pain-free restraint for swine was developed using nine mixed-breed domestic pigs. Each animal was administered a first-stage drug combination consisting of meperidine hydrochloride and azaperone in the caudal thigh muscles, followed after 20 minutes by a second-stage group of injections consisting of ketamine hydrochloride combined with morphine sulfate in the same muscles of the opposite leg. A mean surgical anesthetic time of 60.6 +/- 18.6 minutes was achieved with this regime and it was found that total anesthetic time could be doubled by a second injection of the ketamine and morphine components alone. All animals had a rapid, uneventful recovery. This combination regime not only provided reliable, long-acting anesthesia but was administered easily, required no tracheal intubation and produced no significant changes in the animals' heart rate or body temperature during the anesthetic period.

Anesthesia↗
PubMed1985

Eucapnic voluntary hyperventilation of compressed gas mixture. A simple system for bronchial challenge by respiratory heat loss.

Eucapnic voluntary hyperventilation (EVH) of cold, dry air has been shown to be an effective stimulus for bronchoconstriction in people with reactive airways. The system for respiratory heat exchange (RHE) challenge can be greatly simplified from what is presently used. A relationship was derived which predicts that a single fraction of inspired CO2 (0.0489) will produce near normal alveolar CO2 over a wide range of voluntary hyperventilation. This relationship was verified in 19 normal subjects who performed a total of 110 periods of hyperventilation with minute ventilation (VE) randomly distributed between 40 and 105 L/min. The experimentally determined CO2 production of the voluntary hyperventilation was found to be 3.72 ml/min per L/min over a range of VE from 40 to 105 L/min. Next, a group of 10 patients with exercise-induced asthma (EIA) were challenged with a standard exercise protocol, ventilating ad libitum from a source of dry air at room temperature. On another day, the same pattern of VE, and hence RHE, was required of them using the simplified EVH scheme. The average decreases in forced expiratory volume in one second and specific airway conductance were 32 +/- 10% and 66 +/- 13%, respectively, after the exercise challenge, and 33 +/- 12% and 73 +/- 12% after EVH. The difference between corresponding mean values was not significant. We conclude that a simplified EVH challenge can be done using a single dry gas mixture without the need for cooling inspired gas or monitoring end-tidal fraction of CO2. This test can be used to identify and study patients with EIA without the requirement for an exercise challenge or the need for elaborate gas conditioning and monitoring equipment.

Adult↗
PubMed1985

The influence of clothing on human intrathoracic pressure during airblast.

Exposure to airblast can result in injury to the lungs and other gas-containing organs. The mechanism of lung injury is not clearly understood, but may be related to the rapid increase in intrathoracic pressure (ITP) which is produced when the blast wave strikes the chest wall. The purpose of this study was to determine if ITP during airblast would be influenced by several different types of protective clothing. Ten healthy young male volunteers were exposed to airblast while standing face-on and wearing 1) military fatigues (control condition); 2) fatigues with field jacket; 3) fatigues with ballistic armor vest; 4) fatigues with ceramic vest; 5) fatigues with ceramic vest over the ballistic vest. The incident blast waves simulated artillery muzzle blast. In each subject, an esophageal strain-gauge pressure transducer measured ITP during the blast. The pressure signal was analyzed for ITPmax, and maximum rate of rise of ITP (dP X dt max-1). In addition, the power density spectra of each ITP wave was computed and the peak frequency (fp) and centroid frequency (fc) were calculated. When the subjects wore the ballistic vest, the mean ITPmax was higher (p less than 0.05) than when they were exposed to airblast in fatigues alone. ITPmax was not influenced by the other clothing ensembles. The mean dP X dtmax-1 was not significantly different with any protective clothing ensemble. Clothing had no significant effect of fp, but with the ballistic vest, the mean calculated fc was higher (p less than 0.05) than that for the fatigues alone.(ABSTRACT TRUNCATED AT 250 WORDS)

Aerospace Medicine↗
PubMed1984

Pharmacokinetics of intravenously administered desmosine in sheep.

The pharmacokinetics of desmosine following a 5 mg intravenous dose was determined in five sheep. The biological half-life (t 1/2 beta) of desmosine varied between 81-489 min. Urinary recovery of unchanged desmosine indicated that the compound is not extensively metabolized and that the primary route of elimination is via the kidney.

Amino Acids↗
PubMed1983

Thrombocytopenia and low-dose heparin.

We present two cases in which thrombocytopenia developed during low-dose heparin therapy. They seem to represent the spectrum of heparin-associated thrombocytopenia described by Carreras. Because of the increasing use of low-dose heparin for thromboembolism prophylaxis, and because patient reexposure to heparin is not uncommon, the identification of even a modest fall in platelet count in association with heparin therapy is important.

Aged↗
PubMed1979

A simple technique for managing a bronchopleural fistula while maintaining positive pressure ventilation.

The development of a bronchopleural fistula (BPF) is an infrequent, but potentially devastating complication of positive pressure ventilation. A case report is detailed in which a BPF arose in a patient on controlled ventilation with a PEEP of 22 cm H2O. Within 12 hours, fistula flow was continuous and accounted for 75% of the delivered tidal volume. PEEP fell rapidly during expiration; oxygenation steadily deteriorated as the aAO2 fell 0.27 to 0.14. Conventional treatment methods were unsuccessful, and a system was constructed for adding controlled levels of positive pressure ot the pleural space on the side of the BPF. By decreasing the expiratory transpulmonary pressure difference (PEEP minus pleural pressure), the fistula leak was greatly decreased, and PEEP and oxygenation were stabilized. This system can be rapidly constructed at the bedside with equipment routinely available in most hospitals and offers the ability to adjust the expiratory transpulmonary pressure, lung volume, and BPF flow while maintaining positive pressure ventilation with PEEP.

Adolescent↗
PubMed1977

Total parenteral nutrition: a guide to therapy in the adult.

Total parenteral nutrition (TPN), often referred to as intravenous hyperalimentation, is a complex technique for parenteral feeding that can be lifesaving. A basic knowledge of the theory behind, indications for, and hazards of TPN can help the practitioner determine which of his patients will benefit from this procedure. In the community hospital, where a skilled hyperalimentation team is not available, TPN can be managed safely by a physician, pharmacist and floor nurse if there is rigid adherence to a strict protocol. This paper presents the basic theory, indications, and contraindications associated with TPN, and details a protocol for administering total parenteral nutrition to the adult, hospitalized patient (Appendices 1, 2).

Adult↗