Pieter Fourie

Effect of various propofol plasma concentrations on regional myocardial contractility and left ventricular afterload

The cardiovascular effects of propofol infusions, designed to maintain constant plasma concentrations, were examined in an open-chested pig model. Regional myocardial contractility was measured with the end-systolic pressure-length relationship (Ees) and left ventricular afterload quantified by the effective arterial elastance (Ea). The propofol plasma concentrations in this study varied between 0 and 7.73 (SEM 0.96) μg/mL. A significant correlation for the increasing propofol plasma concentration and a decrease in myocardial contractility (P = 0.0056) was demonstrated, and the Ea remained constant. This gave rise to a reduction in stroke volume (P = 0.002) and, combined with a decrease in the heart rate (P = 0.000l), led to a reduction in the cardiac output (P = 0.0001). When the propofol infusion was stopped, myocardial contractility did not recover in parallel with the decrease in plasma propofol concentration.

Effect of N2O on segmental left ventricular function and effective arterial elastance in pigs when added to a halothane-fentanyl-pancuronium anesthetic technique

The interaction of various concentrations of N2O and a stable halothane-fentanyl-pancuronium anesthetic technique was examined in nine pigs. Segmental myocardial contractility was measured with the end-systolic pressure-length relationship (Ees), and the effective arterial elastance (Ea) was quantified based on the Windkessel model. The addition of 30, 50, and 70% N2O did not change myocardial contractility or the effective arterial elastance. During the 30 and 70% N2O challenge, however, arterial capacitance decreased significantly from a mean (± SEM) 0.86 ± 0.15 to 0.71 ± 0.0.12 mL/mm Hg with 30% N2O (P < 0.05) and from 0.90 ± 0.09 to 0.71 ± 0.07 mL/mm Hg (P < 0.05) with 70% N2O. A dose-response relationship for the effect on the arterial capacitance could not be demonstrated. We concluded that in the presence of halothane, fentanyl, and pancuronium, N2O does not depress the normal myocardium or change left ventricular afterload. The decrease in arterial capacitance that occurred when 30 and 70% N2O were given was not sufficient to change the effective afterload and appears to be of no importance to normal left ventricular function.

The Political Management of HIV and AIDS in South Africa

List of Figures and Tables Acknowledgements LIst of Abbreviations and Acronyms Foreword A.Whiteside Introduction AIDS, Poverty and Development in Southern Africa The HIV and AIDS Policy Environment in Apartheid South Africa (1982-1994) Biomedical and Workplace Responses in Apartheid South Africa (1982-1994) Public Sector Responses on HIV and AIDS in Apartheid South Africa (1982-1994) AIDS Policy Making During the Mandela Administration (1994-1999) AIDS Policy Making During the First Mbeki Administration (1999-2004) Conclusion: Looking Back and Looking Forward Appendix: AIDS Timeline (1982-2004) Notes Bibliography Index

Preservation of myocardial function and biochemistry after blood and oxygenated crystalloid cardioplegia during cardiac arrest

We compared the ability of blood cardioplegia and oxygenated crystalloid cardioplegic solutions to maintain regional left ventricle contractility and adenosine triphosphate levels after cardiopulmonary bypass. Ten baboons were subjected to 90-minute cardiopulmonary bypass conducted at 28 degrees C. Hemodynamic measurements were made before and after the bypass procedure, and biopsies for high-energy phosphate determinations were performed at different time intervals during and after bypass. The results showed improved maintenance of myocardial contractility (measured with the regional end-systolic pressure-length relationship) with the oxygenated crystalloid solution. Expressed as a percentage of values before bypass, contractility after bypass averaged 81.69% +/- 4.81% and 80.47% +/- 10.05%, respectively, after 10 and 20 minutes using the oxygenated crystalloid cardioplegia. For blood cardioplegia, the corresponding values were 71.9% +/- 8.73% and 64.99% +/- 8.60% (mean +/- standard error of the mean). The 10- and 20-minute postbypass values between the two groups differed significantly (t test, Welch modification: p = 0.0464 and p = 0.0342). Myocardial adenosine triphosphate level was higher immediately after induction of cardiac arrest when blood cardioplegia was used (blood cardioplegia, 6.82 mol.g wet wt-1; crystalloid cardioplegia, 4.95 mol.g wet wt-1; p = 0.0314), but values subsequently equalized.

Effect of halothane, enflurane and isoflurane on the end-systolic pressure-length relationship

Myocardial contractility was measured using the end-systolic pressure-length (ESPL) relationship in dogs subjected to increasing concentrations of halothane (0,5-2 per cent), enflurane (0.77-2.6 per cent) or isoflurane (0.70-2.13 per cent), combined with an infusion 7 ¼g·kg-1 ·min-1 offentanyl, after induction of anaesthesia with 15 mg·kg-1; thiopentone. The relationship between the concentrations of the different drugs and contractility (ESPL) can best be described by ESPL = a + bi(MAC fraction) where “a” is a constant and “b” is the slope of the curve relating ESPL to MAC. At 1.0 MAC values, the ESPL for halothane (69.04 ± 25.83 mmHg· mm-1) did not differ from that of isoflurane (63.19 ± 17.36 mmHg·mm-1). However, the myocardial contractility during 1.0 MAC halothane and isoflurane anaesthesia was better preserved than that of enflurane (38.66 ± 9.73 mmHg·mm-1;:p < 0.01, p < 0.05 respectively).RésuméChez des chiens on a mesuré la relation entre la contractilitê myocardique (mesurée à ľaide de la longueur-pression télédiastolique) (LPTD) et des concentrations croissantes a’halothane (0.5-2 pour cent), ďenflurane (0.77–2.6 pour cent) et d!isoflurane (0.70–2.13 pour cent) combiné à une infusion de 7 μg·kg-1;·min-1; de fentanyl après avoir fait une induction anesthésique avec 15mg·kg-1 de thiopental. La relation entre les différents médicaments et la contractilité (LPDT) peut être mieux décrite par ľéquation LPTD = a + b (fraction MAC) ou a est une constante et b est la pente de la courbe qui met en relation la LPTD au MAC. A des valeurs MAC 1, la LPTD pour i halothane (69.04 ± 25.83 mmHg·mm-1 ) ne différait pas de celle de ľisoflurane (63.19 ± 17.36mmHg·mm-1). Cependant, la contractilité myocardique durant une anesthésie 1 MAC à ľhalothane et à ľisoflurane était mieux conservée que durant une anesthésie à ľenflurane (38.66 ± 9.73 mmHg· mm-1:p < 0.01, p< 0.05).

Postsystolic shortening as an index of regional myocardial ischemia in an experimental model

This study explored the relationship between regional myocardial postsystolic shortening (PSS) and myocardial tissue oxygenation in an open-chested animal model subjected to halothane anesthesia. Regional function was examined with reference to the ventricular pressure-length loop and tissue oxygenation gauged from regional arterial-venous lactate dynamics. Coronary blood flow was decreased in steps by application of an external constriction to the left anterior descending coronary artery. Results indicate that a significant change in PSS (from 7.46% +/- 2.14%, mean +/- SEM to 17.74% +/- 3.31%; P less than 0.00001) was associated with a reduction in coronary blood flow from 81.48 +/- 8.85 to 56.94 +/- 7.12 mL/min/100 g tissue (P less than 0.0012), but lactate extraction across the myocardium did not change (10.54% +/- 3.20% to 12.17% +/- 2.43%). A further reduction in coronary blood flow to 39.84 +/- 5.63 mL/min/100 g resulted in severe PSS (50.62% +/- 6.14%) and lactate production (183.81% +/- 28.80%). The correlation between PSS and lactate production was significant (r = 0.873; SEE = 50.49; P = 0.000001).

Turning dread into capital : South Africa's AIDS diplomacy

BackgroundIn much of the world, President George W. Bush was not admired for his foreign policy and diplomacy. It is therefore ironic that Bush’s single most uncontested foreign policy triumph was an instance of what has now become known as “health diplomacy”. In 2003 Bush launched the President’s Emergency Plan for AIDS Relief, a five-year

Power and Integrated Health Care: Shifting from Governance to Governmentality

15 billion initiative to fight HIV/AIDS, mostly in Africa. The president’s pragmatic health diplomacy may well save his foreign policy legacy. This article argues that a middle power such as South Africa should consider a similar instrumental AIDS diplomatic strategy, to rehabilitate its public health as well as foreign policy images.DiscussionThis article reflects on the emergence and contemporary practice of health diplomacy. In particular, it explores the potential of niche areas within health diplomacy to become constructive focal points of emerging middle powers’ foreign policies. Middle powers often apply niche diplomacy to maximise their foreign policy impact, particularly by pursuing a multilateral agenda. The literature on middle powers indicates that such foreign policy ambitions and concomitant diplomacy mostly act to affirm the global status quo. Instead, this paper argues that there may well be niches within health diplomacy in particular that can be used to actually challenge the existing global order. Emerging middle powers in particular can use niche areas within health diplomacy in a critical theoretical manner, so that foreign policy and diplomacy become a project of emancipation and transformation, rather than an affirmation of the world as it is.SummaryThe article first describes the emergence and contemporary practice of health diplomacy; this is followed by a discussion of niche diplomacy, in particular as it applies to the foreign policy agendas of emerging middle powers. It then reviews South African foreign policy and diplomacy, before situating these policies within the context of emerging mechanisms of south-south multilateralism. The article concludes by synthesizing these elements and advocating for a South African AIDS diplomacy, emphasizing its potential to galvanize a global project of emancipation.

AIDS hyper-epidemics and social resilience: theorising the political

Integrated care occurs within micro, meso and macro levels of governance structures, which are shaped by complex power dynamics. Yet theoretically-led notions of power, and scrutiny of its meanings and its functioning, are neglected in the literature on integrated care. We explore an alternative approach. Following a discussion on governance, two streams of theorising power are presented: mainstream and second-stream. Mainstream concepts are based on the notion of power-as-capacity, of one agent having the capacity to influence another—so the overall idea is ‘power over?’. Studies on integrated care typically employ mainstream ideas, which yield rather limited analyses. Second-stream concepts focus on strategies and relations of power—how it is channelled, negotiated and (re)produced. These notions align well with the contemporary shift away from the idea that power is centralised, towards more fluid ideas of power as dispersed and (re)negotiated throughout a range of societal structures, networks and actors. Accompanying this shift, the notion of governance is slowly being eclipsed by that of governmentality. We propose governmentality as a valuable perspective for analysing and understanding power in integrated care. Our contribution aims to address the need for more finely tuned theoretical frameworks that can be used to guide empirical work.

Response of the heart to acute hypertension during halothane, enflurane, and isoflurane anesthesia.

AIDS has been the most political pandemic in the world for 30 years, and yet political science has viewed it in a mostly descriptive, compartmentalised and theoretically neglectful way. There have been many theories of AIDS, but very little AIDS theory that is informed by politics. This deficit of theory seems to be intellectually counter-intuitive, but may be the result of an epistemic community which is often erroneously constructed as monolithic; its pursuits are deeply informed by funding priorities which favour phenomena with more tangible, short-term results; the incremental biomedical ‘good practice’ responses in some instances crowd out what is perceived as the luxury of deeper, systemic reflection. This article argues that a focus on socio-political resilience can be useful to galvanise political scientific theorising of AIDS. As a heuristic filter, resilience may be useful to advance social sciences analytical narrative regarding the pandemic beyond the negative, to identify and capitalise on the lessons and transformational potential of AIDS and other long-wave shocks.