Biomedical subjects

E Darling

Publications and source records attributed to E Darling.

8 recordsLinked to original sources

PubMed2000

Impact of modifying priming components and fluid administration using miniaturized circuitry in neonatal cardiopulmonary bypass.

Following a succession of changes in circuitry and priming additives between 1993 and 1998, a comprehensive re-evaluation of neonatal cardiopulmonary bypass (CPB) practice was undertaken. Samples from 10 infants (Group 1) undergoing CPB were evaluated for osmolality, oncotic pressure, total protein, hematocrit, glucose, and electrolytes (Na+, K+, iCa2+). These samples were tested at six measurement points: (1) after priming, (2) patient pre-CPB, (3) CPB-start, (4) CPB-mid, (5) CPB-end, and (6) post-modified ultrafiltration (MUF). Prime volumes were also carefully measured as well as the type and amount of volume given during CPB. After evaluating the initial data, changes in protocol regarding mannitol, calcium correction, and oncotic strength on CPB were made. Following implementation of these protocol changes, a second set (Group 2) of 10 infants was identically evaluated. Group 1 prime osmolality was 379 +/- 44 mOsm/kg, while Group 2 prime osmolality was 324 +/- 14 mOsm/kg (p = 0.003). There were no differences in osmolality between groups during bypass and osmolality was unaffected by modified ultrafiltration. Ionized calcium levels were significantly different at the end of bypass between Group 1, 0.6 +/- 0.1 mmol/l; and Group 2, 1.17 +/- 0.24 mmol/l (p < 0.001). In Group 1, there was a 40% drop (p = 0.001) in colloid osmotic pressure (COP) levels from pre-CPB (13.3 +/- 3.4 mmHg) to CPB-end (8.8 +/- 1.2 mmHg). In Group 2, there were no differences in COP during CPB. COP levels of Group 1 and Group 2 at CPB-end were 8.8 +/- 1.2 mmHg and 14 +/- 1.9, respectively (p < 0.0001). Total volume addition during bypass for Group 1 was 363.5 +/- 148.7 ml and for Group 2 was 245.1 +/- 92.2 ml (p < 0.05). In conclusion, progressive changes in neonatal circuits and techniques can have potentially wide-ranging effects on electrolyte and osmotic/oncotic homeostasis. An audit of perfusion management through expanded laboratory tests is recommended, especially in periods of change.

Blood Substitutes↗

PubMed1998

Techniques of paediatric modified ultrafiltration: 1996 survey results.

In September 1996, perfusionists from 50 paediatric open-heart surgery programmes were contacted to identify centres that are currently using the technique of modified ultrafiltration (MUF). Of the 50 centres contacted, 22 (44%) were utilizing the technique. These centres were surveyed on the following: neonatal circuit description, patient entry criteria, MUF circuit description, conduct of MUF, use of extracorporeal safety devices and/or modifications, and technical complications. All 22 centres used roller pumps and membrane oxygenators. In 19 centres, MUF was utilized exclusively in the arteriovenous mode (86%), while two centres (9%) used the venovenous mode and one centre (5%) used both methods. Most (82%) of the 22 MUF centres used a blood cardioplegia system for myocardial preservation. After cardiopulmonary bypass (CPB), these blood cardioplegia systems were often converted for use as MUF circuits in a variety of ways. Other methods of accessing the CPB circuit for MUF included utilizing either a recirculation line or a dedicated port added to the circuit specifically for MUF. Blood flow rates during MUF, pump strategies, haemoconcentrator vacuum levels and endpoints were variable from centre to centre. Technical complications related to MUF were reported by 82% of the surveyed MUF centres. The most common complication, air cavitating into the circuit, was reported by 15 centres. From these data, we propose recommendations on the integration of MUF into CPB circuits, the conduct of perfusion during MUF, and appropriate safety considerations to minimize technical complications.

Cardiac Surgical Procedures↗

PubMed1998

Experimental use of an ultra-low prime neonatal cardiopulmonary bypass circuit utilizing vacuum-assisted venous drainage.

In adult cardiopulmonary bypass surgery, vacuum assisted venous drainage has become a popular technique to augment venous return to the bypass circuit. The application of this technique in neonatal cardiopulmonary bypass surgery could be beneficial to the further miniaturization of neonatal circuitry by coupling radical respositioning of the oxygenator and pump console with decreasing line length. This report communicates the use of an investigational, vacuum assisted venous drainage neonatal circuit that is positioned at patient level utilizing a modified pump console with elevated double head twin roller pumps. The circuit, including the oxygenator, arterial line, venous line, raceway tubing, and a functional level in the venous reservoir has a priming volume of 107 ml. Initial bench and animal tests have demonstrated that this technique may be clinically feasible in CPB applications. With vacuum assisted venous drainage, the goal of asanguinous neonatal cardiac surgery could become a reality. Safety issues must be adequately addressed to ensure that this technique does not impose unacceptable risks.

Adult↗

PubMed1998

Pain and discomfort associated with common hospital procedures and experiences.

To determine whether reliable and valid rankings of pain and discomfort resulting from hospital procedures encountered by advanced dementia patients could be developed from interviews with cognitively intact adults, rankings of pain and discomfort resulting from 16 common procedures were obtained from two samples of hospitalized, nondemented adults using ten- (N = 100) and five- (N = 35) point numeric rating scales (NRS). Reliability was assessed by having 30 additional subjects complete ten-point NRS representing the ten most frequent procedures in a re-arranged order. By repeated measure analysis of variance, the scales discriminated between procedures (F = 35.1, P < 0.001). Subjects could discriminate between pain and discomfort (F = 21.6, P < 0.001). The five-point NRS exhibited better subject discrimination between experiences. Reliability was also acceptable. A five-point NRS produced reliable and valid pain and discomfort rankings for 16 common hospital procedures and experiences. These rankings should prove useful in reducing suffering and can serve as surrogates for quantifying pain and discomfort in dementia patients.

Adult↗

PubMed1997

Practical considerations in sedating the elderly.

CS can safely be administered to the elderly population. The definition of elderly is a subjective term. That is, each patient should be considered as an individual person with different physiologic and psychologic needs. Special attention must be given to ensure a safe environment for induction of sedation. The patient should be fully assessed, keeping in mind the physiologic changes that accompany aging. Elderly patients have an increased variability of drug response. Elderly patients have a decreased requirement for most anesthetic drugs. Elderly patients have an increased redosing interval. Continuous monitoring for signs of intolerance and cautious administration of sedation will help reduce the risks associated with sedation in the elderly.

Aged↗

PubMed1996

The experience and impact of contacting a cancer information service.

Our objective was to review the quality of service delivered by a national cancer information service--the British Association of Cancer United Patients (BACUP)--and to consider the implications for future policy and practice. We used a sample of callers over a 10-day period, responding to a structured postal questionnaire. The sample included patients, relatives, friends, and general public who called the service with any concern relating to cancer. Of the 406 invited to take part, 282 responded (69%). The questionnaire was designed to evaluate the callers' perceptions of the information they received, their perceptions of the nurse's communication skills, the emotional impact of the call, and their overall satisfaction with the service. The results indicate that over 90% of callers evaluated the information they received and the nurse's communication skills positively, and there was no difference between the two major groups of callers, i.e. patients and relatives/friends. Both groups reported that the call had a positive emotional impact on them and that they were satisfied with the service. Emotional impact was predicted by quality of information for patients and nurse's communication skills for friends/relatives; overall satisfaction was predicted by nurse's communication skills for patients and both measures for relatives/friends. We conclude that the telephone is an effective medium for conveying information about cancer, and BACUP is meeting its needs. The needs of patients and relatives/friends are different--principally information for patients and support for relatives/friends--and it may be possible to improve training still further by focusing on those differences. The main challenge for cancer information services is to meet the ever-increasing demand.

Adult↗

PubMed1991

Functional characterization of the Ca(2+)-gated Ca2+ release channel of vascular smooth muscle sarcoplasmic reticulum.

The Ca(2+)-gated Ca2+ release channel of aortic sarcoplasmic reticulum (SR) was partially purified and reconstituted into planar lipid bilayers. Canine and porcine aorta microsomal protein fractions were solubilized in the detergent 3-[(3-cholamidopropyl)dimethyl-ammonio]-1-propane sulphonate (CHAPS) in the presence and absence of 3[H]-ryanodine and centrifuged through linear sucrose gradients. A single 3[H]-ryanodine receptor peak with an apparent sedimentation coefficient of 30 s was obtained. Upon reconstitution into planar lipid bilayers, the unlabelled 30 s protein fraction induced the formation of a Ca(2+)- and monovalent-ion-conducting channel (110 pS in 100 mM Ca2+, 360 pS in 250 mM K+). The channel was activated by micromolar Ca2+, modulated by millimolar adenosine triphosphate, Mg2+ and the Ca(2+)-releasing drug caffeine, and inhibited by micromolar ruthenium red. Micro- to millimolar concentrations of the plant alkaloid ryanodine induced a permanently closed state of the channel. Our results suggest that smooth muscle SR contains a Ca(2+)-gated Ca2+ release pathway, with properties similar to those observed for the skeletal and cardiac ryanodine receptor/Ca2+ release channel complexes.

Animals↗

PubMed1986

Kinetics of rapid Ca2+ release by sarcoplasmic reticulum. Effects of Ca2+, Mg2+, and adenine nucleotides.

A radioisotope flux-rapid-quench-Millipore filtration method is described for determining the effects of Ca2+, adenine nucleotides, and Mg2+ on the Ca2+ release behaviour of "heavy" sarcoplasmic reticulum (SR) vesicles. Rapid 45Ca2+ efflux from passively loaded vesicles was blocked by the addition of Mg2+ and ruthenium red. At pH 7 and 10(-9) M Ca2+, vesicles released 45Ca2+ with a low rate (k = 0.1 s-1). An increase in external Ca2+ concentration to 4 microM or the addition of 5 mM ATP or the ATP analogue adenosine 5'-(beta,gamma-methylenetriphosphate) (AMP-PCP) resulted in intermediate 45Ca2+ release rates. The maximal release rate was observed in media containing 4 microM Ca2+ and 5 mM AMP-PCP and had a first-order rate constant of 30-100 s-1. Mg2+ partially inhibited Ca2+- and nucleotide-induced 45Ca2+ efflux. In the absence of AMP-PCP, 45Ca2+ release was fully inhibited at 5 mM Mg2+ or 5 mM Ca2+. The composition of the release media was systematically varied, and the flux data were expressed in the form of Hill equations. The apparent n values of activation of Ca2+ release by ATP and AMP-PCP were 1.6-1.9. The Hill coefficient of Ca2+ activation (n = 0.8-2.1) was dependent on nucleotide and Mg2+ concentrations, whereas the one of Mg2+ inhibition (n = 1.1-1.6) varied with external Ca2+ concentration. These results suggest that heavy SR vesicles contain a "Ca2+ release channel" which is capable of conducting Ca2+ at rates comparable with those found in intact muscle. Ca2+, AMP-PCP (ATP), and Mg2+ appear to act at noninteracting or interacting sites of the channel.

Adenosine Triphosphate↗