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Left ventricular hypertrophy is a condition with high mortality. An association with insulin resistance and hyperinsulinaemia has recently been suggested. The aim of this study was to examine the effects of isolated hyperinsulinaemia on cardiac weight and haemodynamic regulation. Rats were exposed to hyperinsulinaemia for 7 weeks after adrenalectomy with corticosterone substitution and continuous infusion of propranolol to control counter-regulatory mechanism (n = 15) (AIP group). Hypoglycaemia was prevented by glucose in the drinking water. Hyperinsulinaemic (AIP) rats were heavier and had increased relative masses of the myocardium (left ventricle 17% and right ventricle 20%), kidneys and adipose tissues in comparison with normoinsulinaemic adrenalectomized, corticosterone- and propranolol-treated controls (AP) (n = 10). Blood pressure in the insulin-exposed animals, measured weekly by the tail-cuff method in conscious rats, was not different from (AP) controls over 5 weeks, but increased in the sixth week. At the end of the seventh experimental week, blood pressure measured intra-arterially was also found to be elevated. Heart rate was not changed but total peripheral resistance was about twice that of controls (P < 0.001). Cardiac output and stroke volume was 30-40% lower in the AIP rats (P < 0.05). It is concluded that exposure to elevated insulin levels with control of counter-regulating mechanisms from beta-adrenergic mechanisms and adrenals is not immediately followed by blood pressure elevation. It is, therefore, suggested that early onset of blood pressure elevation after insulin exposure might be caused by insulin counter-regulatory events, causing both insulin resistance and blood pressure elevation. The long-term adaptations may involve a direct influence by insulin as a 'trophic factor' on myocardial and on peripheral resistance levels, followed by increased blood pressure, decreased cardiac and stroke volume.

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INTRODUCTION Currently, around 35-80% of patients undergoing cardiac surgery in the UK receive a blood transfusion. Retrograde autologous priming (RAP) of the cardiopulmonary bypass circuit has been suggested as a possible strategy to reduce blood transfusion during cardiac surgery. METHODS Data from 101 consecutive patients undergoing isolated coronary artery bypass grafts (where RAP was used) were collected prospectively and compared with 92 historic patients prior to RAP use in our centre. RESULTS Baseline characteristics (ie age, preoperative haemoglobin [Hb] etc) were not significantly different between the RAP and non-RAP groups. The mean pump priming volume of 1,013ml in the RAP group was significantly lower (p<0.001) than that of 2,450ml in the non-RAP group. The mean Hb level at initiation of bypass of 9.1g/dl in patients having RAP was significantly higher (p<0.001) than that of 7.7g/dl in those who did not have RAP. There was no significant difference between the RAP and non-RAP groups in transfusion of red cells, platelets and fresh frozen plasma, 30-day mortality, re-exploration rate and predischarge Hb level. The median durations of cardiac intensive care unit stay and in-hospital stay of 1 day (interquartile range [IQR]: 1-2 days) and 5 days (IQR: 4-6 days) in the RAP group were significantly shorter than those of the non-RAP group (2 days [IQR: 1-3 days] and 6 days [IQR: 5-9 days]). CONCLUSIONS In the population group studied, RAP did not influence blood transfusion rates but was associated with a reduction in duration of hospital stay.

Hypoxaemia is an adverse but inevitable consequence of one-lung ventilation (OLV). This article reviews the indications for lung isolation, elucidates why hypoxaemia occurs, and explains the relationship between developments in methods of lung isolation and attenuation of hypoxaemia. Recent advances in endobronchial blockers and strategies for prompt management of hypoxaemia are described.

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