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Biomedical subjects

S C Hall

Publications and source records attributed to S C Hall.

At least 19 recordsLinked to original sources
PubMed1996

Retrograde fibreoptic intubation in a child with Nager's syndrome.

PURPOSE: The authors describe a retrograde fibreoptic technique for tracheal intubation in a micrognathic child with a tracheo-cutaneous fistula. CLINICAL FEATURES: A four-year-old child with Nager's syndrome presented for surgical closure of a tracheocutaneous fistula. A tracheostomy tube had been placed in the neonatal period for management of upper airway obstruction due to severe micrognathia. At 2 1/2 yr of age, after a successful mandibular advancement procedure, the tracheostomy was removed and the child allowed to breathe through the natural airway. Preoperative physical examination revealed an uncooperative child, unable to open her mouth due to limited temporo-mandibular motion. The child was first anaesthetized with ketamine, 70 mg im, then halothane by mask. The authors were unable to open the child's mouth sufficiently to allow rigid laryngoscopy. Attempts at oral and nasal fibreoptic intubation were unsuccessful. Ultimately, the authors were able to intubate nasally by passing an ultrathin Olympus LF-P laryngoscope under direct vision through the tracheocutaneous fistula in a cephalad direction, through the larynx and nasopharynx, then out the nares. An endotracheal tube was then advanced over the fibreoptic scope and positioned distal to the tracheocutaneous fistula. The surgical procedure was successfully accomplished and the trachea was extubated postoperatively without difficulty. CONCLUSION: Retrograde fibreoptic intubation may be an option for airway management of a select group of children who cannot be intubated by traditional techniques.

Child, Preschool↗
PubMed1996

Micronucleus induction in human lymphocytes: comparative effects of X rays, alpha particles, beta particles and neutrons and implications for biological dosimetry.

The cytokinesis-block micronucleus assay in peripheral blood lymphocytes has the potential for being a simple and rapid method of biological dosimetry. This technique has been used to study the induction of micronuclei in the blood from 12 donors after exposure to a range of radiations with track-averaged LET values ranging from 0.26 to 44 keV microns -1. Data based on the average response of the 12 individuals for 250 kVp X rays were found to agree well with results published previously from other laboratories using similar techniques. Low dose-limiting RBE values relative to 250 kVp X rays for the radiations studied were found to be 0.50 for strontium/yttrium-90 beta particles, 6.9 for 20-23 keV microns -1 alpha particles and 17 for 24 keV neutrons. The pattern of the variation of individual radiosensitivity was found to be complex and dependent on dose, and the evaluation of individual radiosensitivity based on the response at one dose only can be misleading. It is concluded that, although the cytokinesis-block micronucleus assay in blood lymphocytes is a radiobiologically appropriate technique to use for biological dosimetry, its practical implementation may be limited by a need to perform individual pre-exposure calibrations.

Adult↗
PubMed1995

Rapid mass spectrometric peptide sequencing and mass matching for characterization of human melanoma proteins isolated by two-dimensional PAGE.

We report a general mass spectrometric approach for the rapid identification and characterization of proteins isolated by preparative two-dimensional polyacrylamide gel electrophoresis. This method possesses the inherent power to detect and structurally characterize covalent modifications. Absolute sensitivities of matrix-assisted laser desorption ionization and high-energy collision-induced dissociation tandem mass spectrometry are exploited to determine the mass and sequence of subpicomole sample quantities of tryptic peptides. These data permit mass matching and sequence homology searching of computerized peptide mass and protein sequence data bases for known proteins and design of oligonucleotide probes for cloning unknown proteins. We have identified 11 proteins in lysates of human A375 melanoma cells, including: alpha-enolase, cytokeratin, stathmin, protein disulfide isomerase, tropomyosin, Cu/Zn superoxide dismutase, nucleoside diphosphate kinase A, galaptin, and triosephosphate isomerase. We have characterized several posttranslational modifications and chemical modifications that may result from electrophoresis or subsequent sample processing steps. Detection of comigrating and covalently modified proteins illustrates the necessity of peptide sequencing and the advantages of tandem mass spectrometry to reliably and unambiguously establish the identity of each protein. This technology paves the way for studies of cell-type dependent gene expression and studies of large suites of cellular proteins with unprecedented speed and rigor to provide information complementary to the ongoing Human Genome Project.

Amino Acid Sequence↗
PubMed1995

Pediatric postanesthesia recovery care.

The PACU is a dynamic environment where children undergo significant physiologic changes. Their safe care is dependent on the concerted, prospective efforts of the medical and nursing staff. This can best be done when the staff is well trained in the care of children and the unit is sufficiently equipped. Attention and leadership from anesthesiologists can ensure ongoing quality care for children.

Anesthesia Recovery Period↗
PubMed1995

Sodium nitroprusside metabolism in children during hypothermic cardiopulmonary bypass.

Ten children, aged 1-7 yr, presenting for repair of complex congenital heart lesions, were prospectively studied. A ketamine, halothane/isoflurane, and fentanyl anesthetic was used. After initiation of hypothermic cardiopulmonary bypass, sodium nitroprusside (SNP) was titrated as necessary to maintain a target mean arterial blood pressure of 35-60 mm Hg. Blood samples drawn immediately prior to starting SNP infusion, every 15 min during infusion, and at 1, 4, and 24 h postinfusion were analyzed for whole blood cyanide (CN-) and serum thiocyanate (SCN-). Blood gas analysis was performed every 30 min during SNP infusion. A maximum CN- level > or = 1.0 micrograms/mL was observed in two children; four others had maximum CN- levels between 0.5 micrograms/mL and 1.0 micrograms/mL (normal, < 0.2 micrograms/mL). No child had a clinically important increase of SCN- subsequent to SNP infusion. There was substantial variability in observed CN- accumulation during SNP infusion. CN- levels during the first 60 min correlated with the average SNP rate of administration (P = 0.02). Cyanide levels rapidly decreased after termination of SNP infusion and were undetectable 4 h postinfusion. Despite the short-term increase of CN- level, no child showed biochemical signs of toxicity (acidosis or increased mixed venous oxygen tension).

Cardiopulmonary Bypass↗
PubMed1994

Comparison of a rigid laryngoscope with the ultrathin fibreoptic laryngoscope for tracheal intubation in infants.

The flexible ultrathin fibreoptic laryngoscope allows placement of endotracheal tubes as small as 2.5 mm internal diameter. The purpose of this study was to document the safety and efficacy of intubation using an ultrathin fibreoptic laryngoscope. Proved safety and efficacy would justify the routine use of fibreoptic laryngoscopy in normal infants to maintain skills needed for management of the difficult infant airway. In this prospective study, 40 infants < 24 mo of age scheduled for elective surgery were randomly divided into two equal groups. After inhalation induction of anaesthesia, in 20 infants the trachea was intubated using direct rigid laryngoscopy, and in 20 using the ultrathin fibreoptic laryngoscope (size 1.8 mm OD) Olympus LFP. Time to successful intubation was recorded, as well as blood pressure, heart rate, end-tidal CO2 and oxygen saturation. Airway trauma in the operating room, the post-anaesthesia care unit, and on the first postoperative day was recorded. The intubation times using rigid laryngoscopy were less than those using fibreoptic laryngoscopy (13.6 +/- 0.9 sec (mean +/- SEM) vs 22.8 +/- 1.7 sec; P < 0.01). Oxygen saturation and end-tidal CO2 readings were not different between the two groups. After intubation, blood pressure and heart rate increased equally in both groups, returning to normal within one to two minutes. There was no difference in the airway trauma between groups. We conclude that the ultrathin fibreoptic laryngoscope is a safe and effective method for tracheal intubation in infants and may be used routinely in order to maintain fibreoptic airway skills.

Anesthesia, Inhalation↗
PubMed1994

Anesthetic considerations for the pediatric plastic surgical patient.

An understanding of the anesthesiologist's concerns during pediatric plastic surgical procedures can facilitate the coordination of efforts between the multiple services involved in the care of these children. Prior to surgery, the child's history is obtained and physical examination is performed. The condition of the airway is the primary concern. Preoperative medication is usually given by oral routes to avoid injections. Induction intubation, maintenance, and emergence are discussed. Specific postanesthesia care is described. Special precautions are given for children having surgical repair of craniofacial anomalies. Cleft lip and palate and mandibular advancement are described.

Age Factors↗