What is the chance of dying under an anaesthetic?

Risks & Complications of Anaesthesia

INTRODUCTION

One of the first questions in anyone’s mind when they are about to have an anaesthetic for a surgical procedure is “what can go wrong?” People want to know what complications can happen and how frequently these occur. In the initial stages of anaesthesia and surgical procedures 160 years ago, there was significant risk associated with the undertaking. However improving the safety of medical interventions has always been at the centre of medical attention and this has resulted in a vastly improved safety record in modern medicine. However no procedure is without risk and in the following section, the risks and complications of anaesthesia will be outlined.

RISKS

It is difficult to know precisely the risk of complications as a result of anaesthesia 160 years ago as good records and data was not collected. However judging from the literature and the complications that were reported it is possible to gauge that there was significant risk. Risk is defined as the probability that an event will occur in a given population. In this instance the population will be all those individuals who have an anaesthetic.

In broad terms it is possible to start with the defining the risk of death occurring as a result of an anaesthetic. Given that a patient is submitting themselves to a situation where they lose complete control over their body for a period of time, the first question asked is how likely this is to result in death. Fortunately in modern medicine this has become a rare event although the exact risk is difficult to define. The reason for this is because if a patient dies one has to be able to say exactly why they died and one also has to know the total number of anaesthetics that have been given for each death that occurs. Many studies have examined this topic and it is accepted that in Australia, the risk of dying from an anaesthetic is approximately 1 in 200 000. This means that if there are 1 million anaesthetics administered in Australia every year, there will be 5 deaths attributable solely due to anaesthesia.

However an anaesthetic cannot be examined in isolation as they are never administered unless a person is having a surgical procedure. Risk has to be understood by including all the factors such as the health of the patient, the procedure being performed, whether it is an emergency and so forth.

Factors that are associated with mortality within the first 7 days of surgery are as follows:-

(1) Patient related – increasing age, gender, physical health

(2) Surgery related – major vs. minor procedures, longer procedures, emergency procedures

(3) Anaesthesia related – experience of the anaesthetist

The physical factors in a patient that increase the likelihood of complications include the presence of ischaemic heart disease, recent heart attack, high blood pressure, lung disease, diabetes mellitus, renal failure, cancer, emergency surgery and major surgery. It is extremely complex to calculate the risk of complications in a patient and this can only be done in broad terms.

COMPLICATIONS

Complications in the postoperative period are common and this has remained the same despite the improvements in medical therapy in the last decade. What is important is that the complications are recognised early and an appropriate response is instituted. In this fashion the development of long term and serious complications can be averted. Due to the fact that the Post Anaesthesia Care Units (PACU) are run by dedicated nursing staff with the appropriate training, the safety of patients has improved.

The complications that can occur can be divided into the various groups and they are as follows:-

(1) Airway – airway obstruction from various causes such as laryngeal swelling or spasm

(2) Lung dysfunction – low oxygen levels, decreased breathing, weakness of the respiratory muscles, vomiting or regurgitation with aspiration of stomach contents into the lungs, fluid in the lungs, blood clots in the lungs and prolonged need for support from the ventilator.

(3) Heart and blood vessels – low blood pressure, low blood volume, heart attack (myocardial ischaemia), irregularities of the heart rhythm, high blood pressure

(4) Bladder and kidney – urine retention, kidney failure

(5) Nervous system – post-operative confusion, delayed awakening, stroke

(6) Complicated acute pain management – inadequate pain relief

(7) Haemorrhage – acute bleeding that may require a return to theatre

(8) Temperature – low and high temperatures

(9) Blood sugar – high and low blood sugar levels

(10) Injuries – eye, mouth and throat, dental, hearing loss

(11) Post Operative Nausea and Vomitting

In summary, the potential complications from anaesthesia and surgery are many and varied and it requires the utmost vigilance on the part of the medical and nursing staff to anticipate and respond rapidly when problems occur.