The role of anaesthesia in interventional radiology

‘‘When you’ve got a hammer everything lookslike a nail’’… Interventional radiology came ofage with the medical profession’s desire to devel-op minimally invasive therapies. One of the greatappeals of interventional radiology was that mostprocedures were carried out under local anaes-thesia, occasionally supplemented by iv sedation.This was embraced by all, as it allowed proce-dures to be undertaken on a day-case or shortstay basis thus reducing the nurse and wardburden, it negated the need for the presence of ananaesthetist and Operating Department Assistant(ODA), and it did not use valuable theatre time.However, is this all-pervading minimalistic culturein the best interest of either the patient or theradiologist?Historically, neuroradiologists have maintainedclose links with anaesthetists through their needfor total patient compliance in carrying outboth diagnostic and therapeutic neuroradiologicalprocedures. General anaesthesia ensures patientimmobility and allows controlled apnoea, permit-ting optimal image acquisition and treatmentdelivery. More importantly, experience has shownthat should a complication occur during a pro-cedure, such as aneurysm rupture, it is impossibleto control the situation by coil delivery anddetachment unless the patient remains absolutelyimmobile. These gold standards of anaesthesia arebecoming increasingly necessary in general inter-ventional work. It is no longer appropriate for theoperator/anaesthetist role to be borne by the inter-ventional radiologist alone. Reports for training ofnon-anaesthetic staff in the provision of sedation,monitoring and recovery of patients have beenpublished [1]. The advice includes the need to bewell versed in the pharmacology of opioids, benzo-diazepines and their respective reversal agents;that staff need to be trained in the recovery andmonitoring of patients and need 5 yearly up-dates in resuscitation techniques such as advancecardiac life support. In spite of these reports,recent media reports have again highlighted theincrease in mortality rates in hospital patientsundergoing procedures using sedation techniqueswhen they are carried out by non-anaestheticpersonnel.Assessment of patients prior to sedation is atbest cursory, usually taking the form of a sim-plified patient checklist. Most radiological unitsdo not routinely use the categories describedby the American Society of Anaesthesiologists.Although sedation techniques are safe and with-out mishap in the majority of individuals, thereare certain patient groups in whom cautionshould be exercised, for example extremes ofage [2], morbid obesity or wasting, active bleedingand concurrent systemic illness (cerebrovascular,cardiovascular, respiratory, liver or renal disease,infection and blood dyscrasias). Radiologicalinvestigation of children is a case in point. MRIis becoming increasingly used in the paediatricpopulation as it produces excellent cross-sectionalimages without a radiation burden. MRI requiresthe patient to be completely immobile for a rela-tively long period of time in a rather noisy andenclosed space. To achieve this, dedicated pae-diatric centres have established nurse-led sedationservices, with a high published success rate andno adverse respiratory events [3], a practice fromwhich many lessons can be learnt.It is in high risk groups that more and more‘‘minimally invasive’’ interventional techniquesare being undertaken. As a result, we are makingourselves more vulnerable to the possibility ofsuboptimal practice in the use of sedation becauseof an increase in the unpredictable and unreliableresponse in these patients to the administeredagents. Frequently, analgesia in the form ofopioids is given as an adjunct to iv sedation, soadding to the difficulties in management of thepatient’s airway and respiratory depression.Together, these agents are synergistic in theirunwanted side effects such as decreasing patientcooperation and increasing irritability. Conver-sely, the increasing complexity of interventionalprocedures necessitates greater control over thedegree of patient compliance if treatments are