Role of Anaesthesiologist in Cardiac Cath Lab
Kalpana Shah*
Introduction
Ever Since Forsmann introduced cardiac
catheterization in man, the science of angiography has matured from being at various stages an experimental procedure, a research tool, a diagnostic modality and now a therapeutic option. The Cath Lab which was once a glorified X-Ray unit has now become a high end operation theatre where complex cardiac surgical procedures and vascular procedures are carried out percutaneously. The Anaesthesiologist has therefore become an integral part of the cath lab team. What was once called the cath lab is therefore now more appropriately termed the catheterization suite.
Although the procedure is visibly a small puncture in the groin, intracardiac manipulation makes it have the same major haemodynamic effects as major open heart surgery. In today’s era of hard sell for minimally invasive, day care and even “out patient” cardiological interventions, often the cardiologist may have difficulty accept this, but the reality is reflected in morbidity and mortality rates that are not very different from those of major cardiac surgery. A good cardiological outcome is therefore increasingly dependent on the presence and more importantly the presence of mind of the anaesthesiologist in the cath lab.
Amazingly, there isn’t much awareness amongst the personnel in the cath lab suite about the need for an experienced anaesthesiologist during a routine procedure. It is not uncommon for everybody to be frantically phoning and hunting around for an anaesthetist with a seriously haemodynamically compromised patient on the angiography table.
Many senior anaesthesiologist working in busy cardiac surgical practices including the author have bailed out scores of patients from the catheterization lab, Author thinks that for better procedural and patient outcomes, catch labs across the country need the presence of an experienced anaesthesiologist at all given times.
Building the infrastructure
An operating room anaesthesiologist does find the catheterization suite as “unknown”. Access to the patient in the catch lab is difficult due to fluoroscopy equipment being all around the patient, dimmed light and moving tables. Priorities of an anaesthetist like intravenous access, airway, oxygenation are at times not well appreciated by the attending staff. The anaesthetist’s role begins from the planning stage. Access points for gases, ventilator, pulse dosimeter, warming blankets should be conveniently located. The emergency trolley should be located within easy reach and well stocked and refilled.
A recovery area in the lab premises should be provided for patients to be monitored and comfortable prior to the procedure and after the intervention where sheath removal takes place. The patient should be stabilized here before he is wheeled back to day care or ICU. Often the biggest discomfort for the patient here is to relieve himself of a full bladder, which is the result of the osmotic effects of the radio opaque dye.
The need for adequate transfer monitors for the event free transfer of patients to and from the cath lab suite cannot be overemphasized. Finally, the technical staff must be trained and certified in Advanced Cardiac Life Support (ACLS) as that helps in having a protocol in case of an arrest situation.
Role of the anaesthetist in routine procedures
The anaesthetist’s role begins with counselling the patient, calming him down, knowing about his allergies, previous history of drug reactions, and providing fully monitored anaesthesia care, light sedation, and analgesia. A common cause of great inconvenience to some patients is the cold environment in the cath lab, which is mandatory for smooth functioning of the expensive computerized cath lab equipment. Provision of warming blankets that are safe for the patient are a boon in this situation.
Prevention of renal failure
The commonest side effect of the radio-opaque dye is renal failure. A large number of patients coming to the cath lab are elderly patients, often diabetics with low GFR. Although the serum creatinine may be normal, it is not uncommon to have the renal function as much as 50 to 60% compromised. Adequate hydration. appropriate use of diuretics, minimizing and monitoring use of dye, use of nonionic dye, and use of mucomix are some of the valuable methods of maintaining these kidneys well perfused and minimizing insult.
Maintaining anticoagulation
Every patient in the cath lab is on some form of antiplatelet drugs and for the procedure will need heparin. In addition some acutely ill patients will need GP 2-3b inhibitors. Whilst stent patency often depends on adequate monitoring of antiplatelet agents as well as anticoagulation, the dangers of anticoagulant overdose are real and life threatening. It falls into the purview of the anaesthetist to maintain anticoagulation and antiplatelet activity within strict parameters. Fortunately with the availability of gadgets and investigative modalities like the ACT machine Thromboelastogram, and platelet mapping, objective assessment of anticoagulation and antiplatelet activity is possible.
Antibiotics and aseptic protocol
The use of appropriate antibiotics and maintenance of aseptic protocol are vital to the success of intracardiac manipulations. The anaesthesiologist with vast experience of aseptic protocol in operation theatre is the best quality control officer in this regard.
Rigors due to pyrogens
This extremely common occurrence in spite of routine administration of prophylactic hydrocortisone in almost all cath labs is a nuisance and great discomfort to both patient and cardiologist alike. Careful aseptic protocol and no reuse protocol of disposables is the only way to minimize this. Collection of irrigating fluid in open bowls and their administration intravenously is to be deplored.
Uncontrolled diabetes and associated medical conditions
Nothing can replace good preoperative assessment and preparation in bringing a well prepared patient to the cath lab. Unnecessary post procedural transfers to the Intensive care unit are source of a great alarm, inconvenience and expense to the patient can bring disrepute to the cardiologist and the family physician alike.
Problems during sheath removal
Often an expertly performed intracardiac manipulation is compromised by poorly performed and supervised sheath removal. Not only do haematomas and pseudoaneurysms contribute to unwanted morbidity, vasovagal collapse during sheath removal is too common an occurrence to be taken lightly
Challenges for the Anaesthesiologist
Anaphylaxis: by far the biggest challenge for the anaesthetist is the management of haemodynamic collapse and cardiac arrest. The commonest cause for this is anaphylactic reaction to dye.
With the increasing acceptability of PAMI (percutaneous angioplasty in Acute Myocardial Infarction) has caused a paradigm shift in the characteristics of the angiography patient. It is not unusual to have a patient in cardiogenic shock with intraaortic balloon pump and ventilator being brought in to the cath lab for a rescue PTCA. Often such patients will have life threatening arrhythmias like VF requiring Cardioversion and antiarrhythmic therapy. Managing Acute MI and ongoing ischaemia is therefore yet another additional responsibility that the modern anaesthesiologist must shoulder.
How the family physician can help
Prevention is better than cure. Preprocedural evaluation can not only help in identifying a high risk patient but also gives us an additional knowledge about the pathophysiology of the disease, which can help in fine tuning the anaesthetic to be administered so as to optimize patient condition.
Preoperative counselling brings a cooperative patient to the cath lab suite as he is aware that although the procedure will be carried out under local anaesthesia he will be well looked after by the attending anaesthesiologist.
Today routinely CBC, S Creatinine, HIV HBsAg are done for all patients coming to cath lab. To this the discerning family physician should add X Ray chest and 2-D echo. Selected patients having COPD or a history of smoking benefit immensely from a chest physician consult and a couple of physiotherapy sessions and nebulisation. All patients coming to cath lab are usually administered aspirin and clopidogrel. Addition of an H2 receptor blocker and sucralfate in selected patients could reduce the incidence of erosive gastritis and improve outcomes in incidences of aspiration pneumonitis, two major causes of morbidity in this subgroup of patients.
Special Situations
Management of children in the cath lab poses unique challenges. Evaluation of a child would differ from an adult as he would be required to be given a general anaesthetic, hence the suite needs to be well equipped for a paediatric set up.
Conclusion
The cath lab today is becoming increasingly a place for complex intracardiac interventions. An experienced anaes-thesiologist with support from the family physician can greatly improve patient outcomes. Behind every successful cardio-logical interventional outcome is the hard work of a dedicated and committed anaesthesiologist.
An operating room anaesthesiologist, often feels and describes the environment of the catheterization laboratory as ßunknownÞ.
Patients at times are not fully aware of the procedure to be done, unprepared patient is taken up, where the starvation, allergies and a proper preoperative evaluation is not done; anaesthetist are usually called in at the nth hour to manage a challenging case.
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