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Biomedical subjects

G K Lighthall

Publications and source records attributed to G K Lighthall.

5 recordsLinked to original sources
PubMed2006

An interchangeable Mapleson A-E breathing system is practical and cost effective.

BACKGROUND: In locations where oxygen and anesthesia gas supplies are limited, and where circle systems are not practical, means to reduce fresh gas flow during maintenance of inhalational anesthesia are of potential value. We investigated whether a common transport breathing apparatus could be modified to allow interchange between Mapleson D (Map-D) and Mapleson A (Map A) configurations. METHODS: A common Map-D transport system was converted to a Map-A system by switching positions of the exhaust valve and the elbow connector where fresh gas is delivered; these two breathing systems were compared in this study. The key question was whether rebreathing of CO2 could be eliminated at a lower fresh gas flow rate (FGF) with the Map-A design. A structured protocol was followed. RESULTS: A mean decrease in FGF of 2.8 l/min was seen with the Map-A apparatus when compared with the Map-D (P=0.003). With no significant differences in physiologic or anesthetic variables, FGF/V(E) was significantly lower with the Mapleson A configuration than with the Mapleson D system design (1.1 vs. 1.8; P=0.007). The extent to which FGF could be lowered when switching between Mapleson D and A systems correlated strongly with the patients' respiratory rate while under anesthesia (r=0.45, P<0.01). CONCLUSIONS: Cost and resource savings can be realized through the use of a breathing system modification that achieves appropriate ventilation at lower fresh gas flows.

Adult↗
PubMed2004

Correction of intraoperative coagulopathy in a patient with neurofibromatosis type I with intravenous desmopressin (DDAVP).

A patient with the genetic condition neurofibromatosis type I and no known coagulopathy undergoing cesarean delivery, had diffuse uterine and surgical site bleeding that was not correctable by oxytocin, methylergonovine and PGF2 alpha. Despite good uterine tone, hemorrhage continued from the uterus and the surrounding tissues, persisting even after surgical ligation of the uterine arteries. With no change in her condition, which was behaving clinically as a coagulopathy, an infusion of desmopressin acetate (DDAVP) was begun. The patient's bleeding promptly resolved shortly after infusion of this agent. A review of relevant literature suggests that platelet reactivity of patients with neurofibromatosis type 1 is attenuated in some in vitro conditions. Thus, there may be some theoretical basis for using DDAVP in patients with neurofibromatosis type 1 who have bleeding problems with no other known source, such as in the case presented here.

Adult↗
PubMed1999

A comparison of the onset and clinical duration of high doses of cisatracurium and rocuronium.

STUDY OBJECTIVE: To determine the onset and clinical duration of cisatracurium and rocuronium in equipotent doses in balanced opioid/isoflurane anesthesia. DESIGN: Randomized, controlled study. SETTING: University hospital. PATIENTS: 40 healthy patients scheduled for elective surgery. INTERVENTIONS: Patients underwent anesthesia induction with thiopental or propofol with a cisatracurium intubating dose of either 0.15 or 0.2 mg/kg or a rocuronium dose of either 0.9 or 1.2 mg/kg. These doses correspond to three and four times the ED95 dose. MEASUREMENTS AND MAIN RESULTS: The onset time and time to 25% recovery of baseline first twitch in a train-of-four were determined using an accelerometric sensor. Rocuronium had a faster onset time that cisatracurium at equipotent doses (3 x ED95: 134 vs. 220 sec respectively, and at 4 x ED95: 95 vs. 162 sec). Recovery tended to be faster, but not statistically different for cisatracurium compared to rocuronium. CONCLUSIONS: With equipotent intubating doses of rocuronium and cisatracurium, rocuronium produces a more rapid onset of muscle relaxation. The data suggest a tendency toward more rapid clinical recovery of cisatracurium compared to equipotent doses of rocuronium, although these differences were not statistically significant.

Androstanols↗
PubMed1992

The chromosomes of Leishmania.

Chromosome size polymorphisms occur in Leishmania such that each strain of a given species has a distinctive molecular karyotype. Despite this variability, the chromosomal similarities among closely related strains of Leishmania are sufficiently characteristic to permit classification of unidentified clinical isolates. Mechanisms generating chromosome size polymorphisms are related to chromosomal evolution. In this review, Geoffrey Lighthall and Suzanne Giannini explain that the chromosomal profiles of members of different species may be diverging from a conserved 'consensus' karyotype at different rates, and present a current understanding of the genomic organization of Leishmania with emphasis on chromosomal elements.

Journal Article↗