Search PubMed⌕ Search

Biomedical subjects

C M Heard

Publications and source records attributed to C M Heard.

31 records · Page 2Linked to original sources
PubMed1998

A report of the use of the Dynamic Objective Risk Assessment (DORA) score in the changing pediatric intensive care environment.

OBJECTIVE: To assess the clinical use of the Dynamic Objective Risk Assessment (DORA) severity of illness score in a site remote from its development. DESIGN: Prospective chart review. SETTING: Tertiary referral pediatric intensive care unit (PICU). PATIENTS: One hundred sixty consecutive admissions involving 621 patient days. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Pediatric Risk of Mortality (PRISM) scores were collected daily for all PICU patient days. Collection of data was performed by a physician not directly involved in the ordering of vital signs or laboratory data. The daily DORA score was calculated from the previous day's PRISM score and the admission PRISM score according to a previously described formula. The DORA score determines the patient's risk of mortality for the next 24 hrs. Also documented were the tests not ordered for each patient day. The sensitivity and specificity of the DORA score in our patient population were very similar to that previously reported using the previously described 1% cutoff for predicted mortality. We also noted that the tests ordered were related to the physician's perception of the patient's degree of sickness, and were themselves predictive of outcome. CONCLUSION: An outcome scoring system created in one group of PICUs can be applied to patients in another PICU remote from where the scoring system was developed with similar ability to predict outcome.

Adolescent↗
PubMed1996

Ion-pairing interactions between 99MTc-based myocardial imaging agents and oleic acid.

PURPOSE: The purpose was to test the hypothesis that ion-paired facilitated transport is of importance in successful myocardial uptake of cationic imaging complexes. In vitro ion-pairing interactions between oleic acid and seven cationic technetium-99m complexes based on the ligands 1,2-bis[bis(2-ethoxyethyl) phosphino ethane] (tetrofosmin), 1,2-bis(dimethyl phosphino ethane) (DMPE) and 1,2-bis(diethyl phosphino ethane) (DEPE) has been studied. The complexes studied were: [99mTc O2 (tetrafosmin)2]+ (commercially available as myocardial perfusion imaging kit, Myoview), [99mTc O2 (DMPE)2]+, [99mTc O2 (DEPE)2]+, [99mTc Cl2 (DMPE)2]+, [99mTc Cl2 (DEPE)2]+, [99mTc (DMPE)3]+ and [99mTc (DEPE)3]+. METHODS: Ion-pairing interactions were monitored using a rotating diffusion cell containing a solid supported liquid membrane and by formation of lipid monolayers. RESULTS: Depletion of complex from the donor phase into an isopropyl myristate model membrane was generally in proportion to distribution coefficient and transfer to the receptor compartment was in all cases very small. However, by the inclusion of 5% w/v oleic acid, which is used in myocardial metabolism, partitioning was enhanced by amounts which varied depending on the tendency to form complex/oleate ion-pairs. Transfer to the receptor compartment was increased for most complexes when given sufficient time to diffuse through the membrane. The complex [99mTc O2 (tetrofosmin)2]+ appeared to form particularly stable ion-pairs with oleic acid. Monolayer formation also indicated ion-pairing interactions. CONCLUSIONS: The results suggested that whether or not a complex is taken up by the myocyte may depend on its ability to 'hitch a ride' by ion-pairing with the myocytes energy source--a molecule of long chain fatty acid.

Cations↗
PubMed1996

Hearing loss following spinal anaesthesia with bupivacaine.

The purpose of this study was to determine the incidence, degree and reversibility of hearing loss following spinal anaesthesia with bupivacaine and secondarily to see if there is a relationship between post-spinal headache and hearing loss. A prospective series of 35 patients admitted for elective Caesarean section under a standardized spinal anaesthetic was investigated. Otolaryngological examination and pure tone audiometry in the frequency range 250 Hz to 8 KHz were done on the day before surgery and on post-operative days 1 and 5. Five patients developed a reversible sensorineural hearing loss (mean loss 14.6 dB). This loss was either unilateral (3) or bilateral (2) and affected the low frequencies in all five patients. The demographic data for both groups (i.e. no change in hearing/sensorineural loss) was similar for age, weight, height, blood pressure change and level of sensory block. There was no association found with post-spinal headache.

Adult↗
PubMed1996

Oral midazolam premedication for paediatric day case patients.

Forty-nine children having day-stay surgical procedures were randomly assigned to receive oral midazolam 0.75 mg.kg-1 or placebo in a double blind fashion. The child's level of anxiety was assessed before premedication using parental, child and observer scales. The child and observer anxiety scores were repeated in the anaesthetic room. Most children presented for anaesthesia in a calm state, irrespective of whether they had received midazolam. Parents tended to overestimate their child's level of anxiety. Observer anxiety scores reliably predicted behaviour during induction of anaesthesia in the absence of a sedative. Observer scores decreased in the midazolam group (P < 0.02), but not in the placebo group, children below six years having the greatest decrease with midazolam. The median time to discharge from hospital was delayed by 30 min in the midazolam group (P < 0.01). Children do not require routine sedative premedication for day case procedures, but oral midazolam is useful in producing calm behaviour in those children with high observer anxiety scores.

Administration, Oral↗
PubMed1995

Does solute stereochemistry influence percutaneous penetration?

The stratum corneum, the rate-limiting barrier to percutaneous penetration, is made up of several components, principally keratin and ceramides. These are potential sources of chiral discrimination that could result in differential diffusion rates, dependent upon the stereochemistry of the solute. Although binding to keratin can occur it is not a stereoselective process [percent binding to solubilised epidermal keratin: (R)-propranolol 7.9 +/- 1.7, (S)-propranolol 8.3 +/- 2.0]. On the other hand, studies with ceramide monolayers produced qualitative evidence of dose-dependent stereoselective interaction when the pure diastereomers of ephedrine were present in the aqueous subphase which suggested that differences in diffusion rates might occur in skin. However, the differences in permeation rates in vitro for these diastereomers through human skin were not statistically different [(+)-(1S,2R)-ephedrine 119.1 +/- 2.6 micrograms/cm2, (-)-(1R,2S)-ephedrine 107.0 +/- 3.9 micrograms/cm2, 12 h]. Time averaging, involving contributions from binding to all lipid headgroups present in the intercellular channels, may obscure specific differential interactions. Further, any stereospecific interaction may be subtle and readily overwhelmed if diffusant concentration is greater than the capacity of the skin to differentiate between stereoisomers. Evidence for intrinsic stereoselectivity in skin permeation has therefore yet to be obtained.

Ceramides↗
PubMed1995

Transport for paediatric intensive care. Measuring the performance of a specialist transport service.

Fifty children were referred for transport to a paediatric intensive care unit (PICU). Two scoring systems were used for the transfer process. A physiology score derived from the paediatric risk of mortality (PRISM) score was performed at referral, before transfer and on arrival on PICU. An interventions score based on the therapeutic intervention scoring system (TISS) was performed for interventions by the referring staff and by the transport team before and during transfer. Critical events during transport were recorded. Three children died at the referring hospital. Forty-seven were transported by the PICU team. No child died or suffered a major physiological deterioration or equipment related problem in transit. Physiology scores did not deteriorate during transfer. Referral physiology scores did not reliably predict the need for major therapeutic interventions by the transport team before transfer. Critically ill children may be transported safely by a specialist team.

Ambulances↗
PubMedDate not supplied

Topical delivery of retinyl ascorbate co-drug. 2. Comparative skin tissue and keratin binding studies.

Retinyl ascorbate (RA-AsA), an ester co-drug of vitamins A (RA) and C (AsA), is proposed as a topical antioxidant/cell division regulator for reducing UV-induced generation of free radicals and disrupted dermal cell growth. The efficacy of dermatological agents is influenced by their retention within the skin, which is increased by the interaction with skin components. Keratin is the major protein (approximately 95%) in the skin, and this paper reports the binding of RA-AsA, RA, AsA, retinol, ascorbic acid palmitate and retinol palmitate to three tissues-human callus, pig ear skin and bovine horn keratin. Tissue samples were incubated with solutions of compounds and the uptake measured as the ratio of bound/free compound at equilibrium. Binding to keratin was assessed using delipidised tissue, and was much higher for the polar compounds, suggesting dipolar/H-bonding interaction. Binding strength was ranked as human > porcine > bovine, but there was no distinction for highly lipophilic compounds. The binding characteristic of native tissues was complicated by lipid content of the tissues. There seemed to be a dual effect. The binding of very lipophilic materials increased with lipid content, implying that a substantial amount is dissolved in the lipid matrix. For highly polar AsA, lipid content decreased the binding, suggesting that the lipid reduced the strong polar interactions with skin protein/keratin.

Administration, Topical↗
PubMedDate not supplied

Use of a physiologic scoring system during interhospital transport of pediatric patients.

OBJECTIVE: To determine the incidence of physiologic deterioration in critically ill and injured pediatric patients during interhospital transport with air and ground ambulance DESIGN: Prospective, descriptive study SETTING: All children were treated in regional hospitals and then transported to a pediatric tertiary care center. PATIENTS: Children (n = 100) with a median age of 1.4 years (range 1 week to 18 years) MAIN RESULTS: Three sets of physiologic scores were calculated: at the time of referral, on departure from the referring hospital, and arrival at the tertiary care center. The incidence of significant physiologic deterioration based on the calculated physiologic scores was 5.6% (n = 4) during ground and 3.4% (n = 1) during air ambulance transports. Critical events occurred in 15% of ground and 31% of air ambulance transports. CONCLUSION: No difference existed in the incidence of adverse events or physiologic deterioration when air ambulance transports were compared with ground ambulance transports for critically ill children by our team. The physiologic scoring system we chose is simple and easy to use for quality assurance.

Adolescent↗