Variable definitions: implications for the prediction of pulmonary complications after adult cardiac surgery

Aim: The aim of this paper was to review the implications that variable definitions have for the prediction of post-operative pulmonary complications after cardiac surgery.

Method: A review of the literature from 1980 to 2002. Selected studies demonstrated an original attempt to examine multivariate associations between pre, intra or post-operative antecedents and pulmonary outcomes in patients undergoing coronary artery bypass grafting (CABG). Reports that described the validation of established clinical prediction rules, testing interventions or research conducted in non-human cohorts were excluded from this review.

Results: Consistently, variable factor and outcome definitions are combined for the development of multivariate prediction models that subsequently have limited clinical value. Despite being prevalent there are very few attempts to examine post-operative pulmonary complications (PPC) as endpoints in isolation. The trajectory of pulmonary dysfunction that precedes complications in the post-operative context is not clear. As such there is little knowledge of post-operative antecedents to PPC that are invariably excluded from model development.

Conclusion: Multivariate clinical prediction rules that incorporate antecedent patient and process factors from the continuum of cardiovascular care for specific pulmonary outcomes are recommended. Models such as these would be useful for practice, policy and quality improvement.

Markers of inflammation in South Asian and European infants from birth to 2 years in Manchester, UK

Inflammatory markers, including serum C-reactive protein (CRP), are predictors of coronary heart disease (CHD) in adults. South Asians in the UK have higher rates of CHD in adulthood than national rates.We tested the hypotheses that South Asian infants would have higher serum concentrations of CRP and homocysteine than European infants up to 2 years of age and that higher infant weight is associated with elevation of inflammatory markers. Infants of South Asian and European origin were investigated in a mixed cross sectional-longitudinal cohort study. Mothers were recruited ante-natally from St Mary’s Hospital,Manchester by postal invitation and telephone call to non-responders. Infants with metabolic or congenital abnormalities, known syndromes or pre-maturity were excluded. Measurements were collected at birth and either 3, 6, 12 or 24 months. High sensitivity CRP and homocysteine were measured by an immulite immunoassay. We used mixed linear modelling to assess whether infant weight, ethnicity, length of follow-up or their interaction were associated with inflammatory makers in infants during follow-up. Data are presented on 306 infants (109 South Asian and 197 European). We found that European infants had higher serum CRP than South Asian infants during follow-up which was of borderline significance.There was no difference in serum homocysteine between ethnic groups during followup and no significant interaction between ethnicity and follow-up. Infant weight was significantly associated with CRP but not homocysteine. In this ongoing longitudinal study,we found little difference in inflammatory markers in infants from birth to 2 years despite markedly higher rates of CHD in South Asian than European adults. Life course exposure to risk factors may play a more dominant role in the development of CHD.

Cardiac rehabilitation in south west Victoria : factors influencing attendance

Background : The benefits of cardiac rehabilitation (CR) programs are well established. Despite these benefits their utilisation remains sub-optimal, with an average of 24% of eligible cardiac patients attending outpatient CR programs across Victoria.
Aims & rationale/Objectives : The objectives of this study were to (a) identify local barriers and enablers to the uptake of hospital-based CR programs, and (b) identify preferred alternatives for the delivery of CR.
Methods : Six hospital-based CR programs within the region agreed to participate in this study. A consecutive series of patients referred to the programs were surveyed by the CR coordinators to identify the local barriers and enablers influencing CR program attendance. In addition, focus groups with CR participants and health professionals were conducted at two hospitals in order to ascertain their views on current programs, suggestions for improvements and alternative methods of CR delivery.
Principal findings : Survey data was obtained from a total of 97 patients referred to the CR programs during the study period, 27 (28%) females and 70 (72%) males. Main reasons given for CR non-attendance were related to distance to travel, cost of petrol, reliance on others for transport and lack of interest or motivation to attend. For CR attenders, main enablers included encouragement by family, medical and other health professionals, and having someone else to drive them. Suggestions for alternative methods of CR delivery included more programs in outlying communities, home and GP based programs, telephone support and a patient manual or workbook.
Discussion : The results of this study provide valuable information for designing strategies to increase utilisation of existing CR programs as well as pilot testing alternative modes of CR program delivery for cardiac patients in rural areas unable to access hospital-based CR.
Implications : These findings suggest that many of the barriers identified could be addressed by a more creative use of existing resources and the provision of CR services in primary care settings.
Presentation type : Poster

Exploring the barriers and enablers to attendance at rural cardiac rehabilitation programs

Objective: The objectives of this study were to: (i) identify local barriers and enablers to the uptake of hospital-based cardiac rehabilitation (CR) programs, and (ii) identify preferred alternatives for the delivery of CR.

Design: A questionnaire administered by local CR coordinators and focus groups facilitated by the research team.

Setting: Six regional hospitals in south-west Victoria offering hospital-based CR programs.

Participants: Patients and their carers referred to and eligible for local CR programs; health professionals working within local CR programs.

Main outcomes measures: CR attendees and decliners demographics, patient and health professional perceived factors which contribute to enabling hospital-based CR attendance, patient and health professional perceived barriers to CR attendance, and receptiveness and preferences for alternative modes of CR delivery.

Results: This study identified distance to travel to hospital-based CR programs the only statistically significant factor in determining uptake of CR. Easy access to transport (63%) and to a lesser extent family support (49%) and work flexibility (43%) were the primary enablers to attendance. Of the 97 study participants, 38% were receptive to alternative CR methods such as programs in outlying communities, evening facility-based programs, home and GP based programs, telephone support and a patient manual/workbook.

Conclusions: The results of this study provide valuable information for designing strategies to increase utilisation and improve patient acceptability of existing hospital-based CR programs. It provides a basis for pilot testing alternative modes of CR program delivery for cardiac patients in rural areas unable to access hospital-based CR.

Markers and risk factors for HCV, HBV and HIV in a network of injecting drug users in Melbourne

Background and aims: Current injecting drug users (IDU) in major street drug markets within greater Melbourne were recruited to a longitudinal study on blood borne viruses. Here we investigated risk factors for hepatitis C virus (HCV), hepatitis B virus (HBV) and HIV infection in these IDU at the time of their recruitment.

Methods : Three hundred and eighty-two IDU completed detailed questionnaires on their drug use and risk behaviours, and provided blood samples for serology testing. These data were analysed using univariate and multivariate techniques.

Results : The overall prevalence of exposure to HCV, HBV and HIV was estimated at 70%, 34% and <1%, respectively. Independent predictors of HCV exposure were history of imprisonment (RR 1.34, 95% CI 1.19–1.52), use of someone else's needle or syringe (RR 1.23, 95% CI 1.07–1.42), >7.6 years length of time injecting (RR 1.21, 95% CI 1.07–1.37), and originating from Vietnam (RR 1.12, 95% CI 1.07–1.18). Independent predictors of HBV exposure were HCV exposure (RR 2.15, 95% CI 1.35–3.43), >7.6 years length of time injecting (RR 1.57, 95% CI 1.17–2.13) and originating from outside Australia (RR 1.60, 95% CI 1.22–2.10). Neither prison- nor community-applied tattoos predicted HCV or HBV exposure. Up to 31% of IDU who injected for 1 year or less were HCV antibody positive, as were 53% of those who injected for 2 years or less.

Conclusions : Ongoing engagement with young IDU, through the provision of harm reduction education and resources, is critical if we are to address blood borne viral infections and other health and social harms associated with injecting drug use.

Skin temperature as a noninvasive marker of haemodynamic and perfusion status in adult cardiac surgical patients : an observational study

Objective
Foot temperature has long been advocated as a reliable noninvasive measure of cardiac output despite equivocal evidence. The aim of this pilot study was to investigate the relationship between noninvasively measured skin temperature and the more invasive core-peripheral temperature gradients (CPTGs), against cardiac output, systemic vascular resistance, serum lactate, and base deficit.

Research methodology
The study was of a prospective, observational and correlational design. Seventy-six measurements were recorded on 10 adults postcardiac surgery. Haemodynamic assessments were made via bolus thermodilution. Skin temperature was measured objectively via adhesive probes, and subjectively using a three-point scale.

Setting
The study was conducted within a tertiary level intensive care unit.

Results
Cardiac output was a significant predictor for objectively measured skin temperature and CPTG (p = .001 and p = .004, respectively). Subjective assessment of skin temperature was significantly related to cardiac output, systemic vascular resistance, and serum lactate (p < .001, respectively).

Conclusions
These results support the utilisation of skin temperature as a noninvasive marker of cardiac output and perfusion. The use of CPTG was shown to be unnecessary, given the parallels in results with the less invasive skin temperature parameters. A larger study is however required to validate these findings.

Intrinsic resistance of female hearts to an ischemic insult is abrogated in primary cardiac hypertrophy

Important sex differences in cardiovascular disease outcomes exist, including conditions of hypertrophic cardiomyopathy and cardiac ischemia. Studies of sex differences in the extent to which load-independent (primary) hypertrophy modulates the response to ischemia-reperfusion (I/R) damage have not been characterized. We have previously described a model of primary genetic cardiac hypertrophy, the hypertrophic heart rat (HHR). In this study the sex differences in HHR cardiac function and responses to I/R [compared to control normal heart rat (NHR)] were investigated ex vivo. The ventricular weight index was markedly increased in HHR female (7.82 ± 0.49 vs. 4.80 ± 0.10 mg/g; P < 0.05) and male (5.76 ± 0.22 vs. 4.62 ± 0.07 mg/g; P < 0.05) hearts. Female hearts of both strains exhibited a reduced basal contractility compared with strain-matched males [maximum first derivative of pressure (dP/dtmax): NHR, 4,036 ± 171 vs. 4,258 ± 152 mmHg/s; and HHR, 3,974 ± 160 vs. 4,540 ± 259 mmHg/s; P < 0.05]. HHR hearts were more susceptible to I/R (I = 25 min, and R = 30 min) injury than NHR hearts (decreased functional recovery, and increased lactate dehydrogenase efflux). Female NHR hearts exhibited a significantly greater recovery (dP/dtmax) post-I/R relative to male NHR (95.0 ± 12.2% vs. 60.5 ± 9.4%), a resistance to postischemic dysfunction not evident in female HHR (29.0 ± 5.6% vs. 25.9 ± 6.3%). Ventricular fibrillation was suppressed, and expression levels of Akt and ERK1/2 were selectively elevated in female NHR hearts. Thus the occurrence of load-independent primary cardiac hypertrophy undermines the intrinsic resistance of female hearts to I/R insult, with the observed abrogation of endogenous cardioprotective signaling pathways consistent with a potential mechanistic role in this loss of protection.

Effect of vitamin D supplementation on vitamin D status and bone turnover markers in young adults

Objective: To assess the vitamin D status of healthy young people living in Northern Ireland and the effect of vitamin D supplementation on vitamin D status and bone turnover.

Design: Double-blinded randomised controlled intervention study.

Setting: University of Ulster, Coleraine, Northern Ireland.

Subjects: In total, 30 apparently healthy students (15 male and 15 female subjects), aged 18–27 years, were recruited from the university, with 27 completing the intervention.

Interventions: Subjects were randomly assigned, to receive either 15 mug (600 IU) vitamin D3 and 1500 mg calcium/day (vitamin D group), or 1500 mg calcium/day (control group) for 8 weeks between January and March. Vitamin D status, bone turnover markers, serum calcium and parathyroid hormone concentrations were measured at baseline and post intervention.

Results: At baseline, vitamin D status was low in both the vitamin D group (47.9 (s.d. 16.0)) and the control group (55.5 (s.d. 18.6) nmol/l 25(OH)D). Post intervention vitamin D status was significantly higher in the vitamin D-treated group (86.5 (s.d. 24.5)) compared to the control group (48.3 (s.d. 16.8) nmol/l) (P<0.0001). There was no significant effect of supplementation on bone turnover markers or PTH concentrations.

Conclusions: This study suggests that young adults in Northern Ireland do not consume an adequate daily dietary intake of vitamin D to maintain plasma vitamin D concentrations in the wintertime. A daily supplement of 15 mug vitamin D3 significantly increased vitamin D status in these individuals to levels of sufficiency. Achievement of an optimum vitamin D status among young adults may have future positive health implications.

Outpatient cardiac rehabilitation attendance in England

Abstract
PURPOSE:
Cardiac rehabilitation is an effective but underprovided treatment for patients recovering from acute cardiac events. The geographical spread of provision has not been investigated recently in any country. This study aimed to investigate the level of participation in cardiac rehabilitation programs of patients following myocardial infarction or revascularization (eligible patients) and the geographical equity of attendance.
METHODS:
Questionnaire data were collected from all cardiac rehabilitation centers in England for the year 2003/2004. The number of patients attending rehabilitation was compared with eligible patients across the 9 Government Office Regions of England as indicated by Hospital Episode Statistics.
RESULTS:
Nationally, 29% of eligible patients attended rehabilitation, while within various regions, the proportion of eligible patients participating in rehabilitation ranged between 14% (95% CI, 13.2-14.3) and 37% (95% CI, 36.6-37.6). Participation also differed significantly by primary cardiac event: myocardial infarction, 25%; percutaneous coronary intervention, 24%; and coronary artery bypass surgery, 66% (P < .001).
CONCLUSION:
The participation rate of eligible patients in cardiac rehabilitation was low in all regions. There were large differences between regions with widely varying incidence of attendance in different parts of the country.