Blood Transfusion

The world’s largest transfusion study in cardiac surgery has changed transfusion practices around the world. Traditionally, internationally accepted best practice for surgical teams undertaking open heart surgery on older patients was to use a liberal blood transfusion regimen.

This practice of transfusing older patients to a higher haemoglobin level was supported by the belief that their body’s physiology and ability to cope with the stresses of surgery made them less able to tolerate lower levels than younger patients. This dogma has been challenged in the international Transfusion Requirements in Cardiac Surgery (TRICS) III trial, the largest ever blood transfusion trial in cardiac surgery, which was led in New Zealand by the MRINZ through the New Zealand Improving Outcomes After Cardiac Surgery Network (IOACS Net).

This global study shows that a restrictive blood transfusion strategy is at least as beneficial as the traditional liberal strategy in patients undergoing cardiac surgery, and may be preferable in older patients due to a lower risk of complications such as stroke, kidney failure, heart attack and death. This finding brought about major change in clinical practice internationally, leading to both improved outcomes and preserving limited supplies of blood products.

The discovery that smoking cannabis is associated with an increased risk of lung cancer was a wake-up call to New Zealand, which has amongst the highest rates of both lung cancer and recreational cannabis use in the world. Thanks to this focused MRINZ research, smoking cessation programmes now have evidence of the risk of lung cancer with cannabis smoking on which to advise the public.

BOB HANCOX, DEPARTMENT OF PREVENTIVE & SOCIAL MEDICINE DUNEDIN SCHOOL OF MEDICINE, UNIVERSITY OF OTAGO, NEW ZEALAND

Cannabis and the Lung

Cannabis is the most widely used illegal drug worldwide. New Zealand has a strong culture of cannabis use, with about half the adult population reporting that they have smoked cannabis at some stage in their lives and one quarter using it in the last year. When compared with tobacco cigarettes, cannabis contains a higher concentration of carcinogens, is inhaled in larger amounts, and entry of carcinogenic compounds into the lower respiratory tract is aided by deeper and longer draws being taken. Despite research finding pre-cancerous abnormalities in the respiratory tracts of cannabis smokers, the link between cannabis use and lung cancer has previously been uncertain with few studies having investigated this potential association.

A landmark national study of the risk of lung cancer with cannabis smoking has produced three major findings. Firstly, there is a positive association between cannabis use and risk of lung cancer, with the risk of lung cancer increasing by 8% for each joint-year (one joint per day for one year) of cannabis use, after adjustment for other factors such a tobacco smoking. Secondly, the bioequivalence in risk compared with smoking tobacco was determined, with one cannabis joint being equivalent to 20 tobacco cigarettes in terms of lung cancer risk. Thirdly, the risk of lung cancer is greater in those who start smoking cannabis when aged younger than 16 compared with those who start when aged 21 or older.

These findings have provided the scientific evidence on which public health campaigns can be based. There has been major international interest in this research, particularly the bioequivalence in risk with tobacco smoking and the high risk in those who start smoking as children.

The success of the trial using kānuka oil to treat eczema is hugely exciting and could now lead to a sustainable and profitable industry for the Tairāwhiti region, providing new jobs for local people. The experience we have gained through our collaboration with the MRINZ has been invaluable, and is leading us to many other opportunities.