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Biomedical subjects

C D Potter

Publications and source records attributed to C D Potter.

12 recordsLinked to original sources
PubMed1998

Oral PowderJect: a novel system for administering local anaesthetic to the oral mucosa.

OBJECTIVE: To assess the feasibility of using an Oral PowderJect (OPJ) to safely deliver a dose of dry powdered anaesthetic to the oral mucosa, producing an analgesic effect. DESIGN: Single centre: Part 1. An open, non-randomised safety study to check for mucosal damage; Part 2. A double blind sham controlled study to test the anaesthetic effect. SETTING: General practice. SUBJECTS: Adult, healthy volunteers (4 male, 10 female). MATERIALS AND METHODS: Part 1. An OPJ was used to deliver powdered lidocaine hydrochloride to the mucosal surface which was then checked visually for damage. Part 2. An OPJ containing lidocaine hydrochloride (active) or an empty OPJ (sham) was fired at the oral mucosa. The treated area and an untreated (control) site were probed with the back end of a dental needle. RESULTS: The OPJ delivery caused no visible mucosal damage. The median VAS score for pain on blunt probing was 10 for the OPJ active sites. This was significantly lower than the median VAS score for the sham sites at 30 (P = 0.0033) and the control sites at 58 (P < 0.0001). CONCLUSIONS: The OPJ can safely deliver powdered lidocaine hydrochloride to the oral mucosa without causing tissue damage. The OPJ delivery of powdered lidocaine hydrochloride can significantly reduce the pain from a blunt needle probe at 1 minute post delivery.

Adult↗
PubMed1996

An approach to the retrieval of thoracic organs for transplantation.

A critical, worldwide shortage of thoracic organs exists. The donor management program at Papworth Hospital, National Health Service Trust, Cambridge, United Kingdom, allows satisfactory transplantation of thoracic organs that initially appear unsuitable. The perioperative organ retrieval team members assess the cardiovascular status of all potential donors and manage suboptimal hemodynamics with hormonal replacement therapy consisting of triiodothyronine, antidiuretic hormone, epinephrine, and insulin. These donors' cardiovascular and pulmonary functions must be within acceptable limits at the time of organ excision. Our standardized approach facilitates objective decision making regarding the appropriate use of donor organs and has increased the number of available donor organs at Papworth Hospital by 30%. Morbidity and mortality rates in thoracic organ recipients have not increased since the authors developed the standardized approach, and more patients have benefited from thoracic organ transplantation.

Decision Making, Organizational↗
PubMed1994

Using "unsuitable" hearts for transplantation.

Donor availability is the single most limiting factor in heart transplantation. From a consecutive series of 100 heart donors, there were 21 which fell well outside our minimum criteria on initial inspection: mean arterial pressure (MAP) more than 60 mm Hg, central venous pressure (CVP) less than 12 mm Hg, pulmonary capillary wedge pressure (PCWP) less than 12 mm Hg, left ventricular stroke work index (LVSWI) more than 15 g.m. on inotropes less than 5 mcg/kg per min. Of these 13 out of 21 had a MAP less than 55 mm Hg, 6 out of 21 a CVP more than 15 mm Hg and 2 out of 21 were on inotropes at more than 20 mcg/kg per min. Following full invasive monitoring another 14 donors fell outside our criteria; 5 had a mean LVSWI of 12.4 g.m. and 9 had a mean PCWP of 19.6 mm Hg. Following the institution of our hormone-based pharmacological resuscitation regime 30 of these donors yielded 19 transplantable hearts and 11 transplantable heart-lung blocks. The other five were not used due to left ventricular hypertrophy (2), inotrope dependency (2) and persistent poor function (1). Twenty-five of the 30 recipients of these organs (83.3%) are alive and well, 4-25 months post transplant. Four early deaths occurred; one arrhythmia (heart), one acute respiratory distress syndrome (heart), one cerebrovascular accident (heart lung) and one infection (heart, lung and liver). One death occurred at 90 days from tamponade (heart). Aggressive and focussed donor management has helped us to maintain our levels of transplant activity, without compromising the outcome--a 30-day mortality of 16.2% in 1989, 11.8% in 1990 and 6.8% in 1991.

Blood Pressure↗
PubMed1994

Measurements of human coronary vascular impedance.

The aim of this study was to develop a method of measuring human coronary circulation impedance in a clinical setting. The authors measured coronary flow reserve (CFR) in 27 patients with chest pain and normal coronary arteries. A Judkins-style, 8F Doppler-tipped angiographic catheter was positioned in the left coronary ostium. Resting coronary flow velocity (RFV) and response to a hyperemic 12 mg intracoronary dose of papaverine (PFV) were measured. The signals were recorded by a recorder connected to a microprocessor with analogue-to-digital converter and a maths coprocessor. Using this the authors could obtain values for impedance at RFV (IR) and at PFV (IP). The CFR was defined as the ratio: PFV/RFV. An impedance index (II) was obtained as the ratio of coronary vascular impedance at peak hyperemia to the impedance at rest. The CFR was 3.2 +/- 1.2 and the II was 0.33 +/- 0.11. There was a strong inverse correlation between the CFR and the II (r = -0.9). The authors conclude that this new approach may allow a further insight into the coronary pathophysiology and may become useful in clinical cardiology, eg, in the assessment of heart transplant and Syndrome X patients.

Adult↗
PubMed1983

Basis for the hypoactivity that accompanies rapid weight gain in hamsters.

The pattern of hypoactivity that accompanies rapid weight gain following septal lesions in hamsters was characterized. Lesioned hamsters displayed reduced levels of running, shorter and slower running bouts, and longer pauses. We examined whether this hypoactivity was due to reassignment of metabolic fuels from supporting physical activity to anabolism, or due to reduced capacity of running to induce psychomotor arousal and mobilize metabolic fuels. Septal lesions were associated with increased rate of ponderal growth and higher titers of circulating growth hormone and insulin. No difference in concentrations of muscle and liver glycogen, percentage of body fat, or the capacity of muscle homogenates to oxidize substrates were identified. Lesioned hamsters ran as fast and as long as control animals on electrical-shock reinforced treadmill, but were unable to generate as much heat in response to injection (0.8 mg/kg) of norepinephrine. We concluded that hypoactivity that accompanies rapid weight gain in hamsters results either from a reduced capacity of running to induce psychomotor arousal and provide incentives that normally motivate that behavior, or from a failure of running to mobilize metabolic fuels at a rate necessary to sustain normal running speed and duration, and not from reduced availability of metabolic fuels or reduced muscle capacity to oxidize metabolic substrates.

Animals↗
PubMed1983

Opiate-receptor blockade reduces voluntary running but not self-stimulation in hamsters.

Naltrexone HCl, a long-acting opiate receptor blocker was administered to female hamsters at two doses, 10 and 20 mg/kg, IP prior to 12 hr of nocturnal running or every 12 hr during access to hypothalamic self-stimulation to determine whether endogenous opiates played a role in either of these two motivated behaviors. Naltrexone suppressed total running activity and speed, and caused an increase in pause time but did not affect the rate of hypothalamic self-stimulation. Furthermore, weight gain was unaffected by four weeks of self-stimulation but was accelerated during two weeks of voluntary running. Thus stimulation of endogenous opiate receptors helps support high levels of voluntary running but is not involved in initiation of running or in maintenance of intracranial self-stimulation in female hamsters. Furthermore, the association of opiate receptor stimulation and increased somatic growth with voluntary running but not with self-stimulation suggests a possible facilitatory role for endogenous opiates in acceleration of growth by exercise.

Animals↗
PubMedDate not supplied

Transforming the "unacceptable" donor: outcomes from the adoption of a standardized donor management technique.

BACKGROUND: Donor management remains one of the most neglected areas of transplantation. A comprehensive donor management regimen has been developed. The results of the application of this strategy form the basis of this report. METHODS: Full hemodynamic data were collected from 150 multiorgan donors between October 1990 and August 1993. The data were collected at the time of donor team arrival, after insertion of a pulmonary artery floatation catheter and immediately before cardiac excision. RESULTS: Fifty-two donors (35%) fell well outside our minimum acceptance criteria on arrival. Twenty-one of fifty-two had a mean arterial pressure less than 55 mm Hg (mean 47 mm Hg) despite inotropic support in most cases; 10 of 52 had a central venous pressure greater than 15 mm Hg (mean 18.0 mm Hg); 2 of 52 had a high inotrope requirement greater than 20 micrograms/kg/min (mean 25 micrograms/kg/min). After the insertion of a pulmonary artery floatation catheter, an additional 13 of 52 donors were found to have a pulmonary capillary wedge pressure greater than 15 mm Hg (mean 19.8 mm Hg), and the final 6 of 52 had a low left ventricular stroke work index, less than 15 gm (mean 12.8 gm). After optimal management, including hormone replacement 44 of 52 donors yielded transplantable organs (29 hearts, 15 heart and lung blocks). Thirty-seven of forty-four patients (84%) were alive and well from 13 to 48 months after transplantation. There were five early deaths (11%) caused by infection (heart), adult respiratory distress syndrome (heart), arrhythmia (heart), cerebrovascular event (heart and lung), and infection (heart, lung, and liver). Two late deaths (5%) occurred as a result of tamponade (3 months, heart) and infection (14 months, heart and lung). Eight of fifty-two organs were still unsuitable for transplantation after optimum management during the splanchnic dissection as a result of inotrope dependency (n = 4), left ventricular hypertrophy (n = 2), and coronary artery disease (n = 2). CONCLUSIONS: The data indicate that, of the organs which initially fall outside our transplant acceptance criteria, 92% are capable of functional resuscitation. Conversely, superficial assessment may not show compromised function. Optimizing cardiovascular performance also has important implications for the viability of all transplantable organs. This aggressive approach to donor management has resulted in the transplantation of 44 donor hearts that may otherwise have been turned down or inappropriately managed.

Adult↗
PubMedDate not supplied

Functional assessment and management of heart donors: a rationale for characterization and a guide to therapy.

BACKGROUND: Traditional methods for the functional evaluation of a donor heart have relied on superficial hemodynamic data and visual inspection of the action of the heart at sternotomy. The International Registry has continued to report significant mortality for heart transplant recipients from primary graft dysfunction that may be due to donor management, donor organ selection, organ preservation, or recipient factors. The literature reports the loss of at least 25% of potential donors because of the provision of inadequate physiologic support. METHODS AND RESULTS: We have now spent several years in establishing and refining a strategy for optimizing donor management, which has resulted in the safe expansion of our donor pool by approximately 30%. Central to this management regimen has been the use of comprehensive perioperative invasive monitoring used by a cardiac anesthetist who takes responsibility for donor management during the retrieval operation. CONCLUSION: This article outlines the technique which has evolved for the functional evaluation of a donor heart, which is now used in our institution as a guide to management and as a basis for decision making regarding organ suitability.

Adolescent↗
PubMedDate not supplied

Cardiovascular dysfunction. A rationale for characterization and a guide to therapy.

Traditional clinical assessment of cardiac function has relied on the indirect measurement of systemic blood pressure, heart rate and rhythm, and central venous pressure. However, because the circulation comprises complex interactions between flow and impedance in two hydraulic systems coupled in series, the usual assumptions drawn from the measurement of only a representative sample of this system can lead to serious errors in interpretation. This is particularly significant in conditions leading to physiologic distortions. Patients undergoing major surgery, or with suspected cardiac dysfunction, can only be adequately managed with a knowledge of both right and left heart pressures, together with the measurement of cardiac output. This report presents a rationale for the use of a simple method for interpreting these data and a guide to optimizing management. For those patients with heart failure who are unable to be sustained with conventional pharmacology, criteria are suggested that may help the clinician decide when more aggressive intervention, such as mechanical assist, is required.

Biometry↗