In patients undergoing cardiac surgery, thoracic epidural analgesia combined with general anesthesia results in faster recovery and fewer complications but does not affect length of hospital stay

June 8, 2006

September 12, 2006

Andrew Roland, K. Anuar Abdul Azizb, Thomas George Day and Martin Scott, Consultant in Anaesthestics (Department of Cardiac Anaesthesia, Aberdeen Royal Infirmary, Aberdeen, Manchester Royal Infirmary and Wythenshawe Hospital, Manchester Respectively)

Joel Dunning, Department of Cardiac Anaesthesia, Aberdeen Royal Infirmary, Aberdeen, Manchester Royal Infirmary and Wythenshawe Hospital, Manchester Respectively

In [adult patients undergoing cardiac surgery], is the use of [Thoracic epidural anaesthesia] associated with [faster recovery, fewer complications and shorter length of stay]

You are the anaesthetist assessing a 75-year-old current smoker with an exercise tolerance of only 200 yds, who is due to have coronary grafting tomorrow. You approach the surgeon to suggest that you place a thoracic epidural prior to induction. He is reluctant for you to do this as he says that epidurals can be dangerous with full heparinisation and anyway he isn't aware of any evidence that it speeds recovery. You decide to summarize the evidence for him.

Medline 1966 to October Week 3 2005 using OVID interface
EMBASE 1980 to 2005 Week 43

[exp Cardiopulmonary Bypass/ OR CABG.mp OR exp Thoracic Surgery/ OR exp Cardiac surgical procedures/ OR Coronary art$ bypass.mp. OR Cardiopulmonary bypass.mp OR exp Cardiopulmonary Bypass/ OR exp Cardiovascular Surgical Procedures/ OR exp Thoracic Surgical Procedures/ OR exp Coronary Artery Bypass/ OR cardiac transplantation.mp. OR exp Heart Transplantation/ ] AND [exp Anesthesia, Epidural/ OR Epidural anaesthesia.mp OR exp Analgesia, Epidural/ OR epidural analgesia.mp OR exp Anesthesia, Conduction/ae, cl, st, td, mo OR exp Anesthesia, Local/ad, ae, ct, st, td, mo OR exp Anesthesia, Spinal/ae, ct, st, td, mo OR exp Nerve Block/ae, ct, st, td, mo] AND [exp ANESTHESIA RECOVERY PERIOD/ OR exp "RECOVERY OF FUNCTION"/ OR "Length of Stay"/ OR exp Intraoperative Complications/ OR exp Postoperative Complications/ OR surgical complications.mp OR *"Postoperative Complications"/] LIMIT [humans AND english language]

Using the reported search, 313 papers were identified on Medline and 368 on Embase. A further paper was found by hand-searching of reference lists. Fifteen papers represented the best evidence on the subject and are summarised below. A further 6 papers were not summarised due to small study size, non-randomised design and our own space constraints (Kessler, Hemmerling, Tenling, Senseth, Liem, Liem).

Various benefits have been reported in combining thoracic epidural anaesthesia (TEA) with general anaesthesia (GA) during cardiac surgery. Liu et al performed a meta-analysis in 2004 which studied outcomes of 1178 patients from 15 studies including eight identified in our search. They found that the use of TEA led to earlier extubation (OR -4.5; 95%CI -7 to -2; p=0.0005) and improved pain scores at rest (OR -7.8; 95%CI -15 to -0.6; p=0.03) and with activity (OR -11.6; 95%CI -19.7 to -3.5; p=0.005) compared to GA alone. Scott et al, Turfrey et al, Barrington et al, Priestley et al, and Royse et al have all confirmed these findings. The meta-analysis also identified a decrease in pulmonary complications (OR 0.41; 95%CI 0.27-0.60; p<0.00001) with Scott reporting a lower incidence of chest infection and better maximal inspiratory lung volume, and Royse identifying better postoperative lung function and cooperation with physiotherapy in their TEA groups. However Priestly et al reported no difference in blood gases, spirometry or chest X-ray appearances in their postoperative TEA group.

Liu also reported decreased dysrhythmias with TEA (OR 0.52; 95%CI 0.29-0.93; p=0.03) although there were no significant differences in myocardial infarction and mortality. But whilst Scott and Turfrey both identified lower incidences of atrial fibrillation (AF) with TEA, Barrington, Priestley and Royse did not. However Scott discontinued Beta-blockade postoperatively which may be confounding factor and it has been suggested that his use of Clonidine as an epidural adjunct might enhance TEA anti-dysrhythmic effect. Jideus et al recognised that whilst TEA suppressed sympathetic activity and protected against postoperative tachycardia and supraventricular premature beats, there was no difference in the proportion of patients developing AF. Nygard's 2x2 factorial studied the effects of TEA, Amiodarone or both as prophylaxis against AF and found Amiodarone but not TEA to be protective.

A number of studies have looked at biochemical markers of myocardial injury in patients undergoing cardiac surgery utilising TEA. Barrington and Priestly measured Cardiac Troponin and CK-MB levels postoperatively and Fillinger et al looked at urinary free cortisol but there were no significant differences between TEA and control groups. Jideus measured Neuropeptide Y (NPY) levels and identified significant falls in their TEA group postoperatively versus control. Berendes et al combined Troponin I, ANP and BNP measurement with transoesophageal echo (TOE) assessment of LV function and identified differences in ANP and BNP responses to surgery in their TEA group. They also recognised that postoperative LV function was better in the TEA group and identified a correlation between peak BNP, Troponin and TOE-derived LV function motion score implying a possible prolonged postoperative benefit.

Other effects have been noted. Scott's group identified significant decreases in acute confusional states and renal failure in their TEA group but whilst there was a lower incidence of stroke this did not reach statistical significance . Royse noted lower rates of post-traumatic stress disorder and postoperative depression in those patients receiving TEA. Salvi et al identified a small subgroup of patients whose developing myocardial ischaemia was attenuated / abolished by institution of TEA. Not surprisingly Fillinger reported that TEA patients required more vasoconstrictor and catecholamine but less vasodilator therapy than control patients.

There is currently no evidence to suggest that use of TEA is associated with earlier hospital discharge although this in part may be confounded by the populations studied. For example 60% of Scott's study population were in receipt of allowances if they stayed in hospital! In Priestley's study, both their TEA and control groups were discharged earlier than non-study patients. Fillinger et al found no significant cost benefits in using TEA.

There is no agreement on the optimal TEA drug regime. Bupivacaine and Ropivacaine are widely used and whilst most authors used opioid supplementation, the two studies reporting greatest anti-dysrhythmic effect used Clonidine.

The major disadvantage of TEA remains the fear of epidural haematoma in the soon-to-be anticoagulated patient. Whilst a small number of individual cases have been reported, increasing number of audits and cohort studies including those by Salvi, Chakravarthy, Sanchez, and Pastor which specifically looked for neurological complications seem to confirm the apparent safety of the technique when basic sensible precautions are taken. Chakravarthy et al reported only 4 temporary neurological deficits in a large series of 2113 epidurals in cardiac surgery patients over a 13 year period . A small proportion of their patients experienced dural or bloody taps but in most cases epidurals were resited and surgery proceeded. Likewise Pastor et al reported a low incidence of dural puncture although three of his series and one each of Scott's, Turfrey's and Salvi's patients underwent negative MRI scanning after developing suspicious lower limb signs. There were no other unexplained neurological deficits or signs of epidural haematoma in any study.

In 2000 Ho et al used mathematical modelling to calculate the statistical risk of epidural haematoma following TEA as between 1:150,000 and 1:1,500 (95% confidence) and up to 1:1,000 (99% confidence) based on published data available at that time. They also acknowledged the importance of factors including presence of a normal coagulation system prior to insertion and removal of the catheter, avoidance of repeated attempts, postponing surgery in the presence of a bloody tap and close neurological surveillance in minimising risk. These precautions are repeated in most studies. It has also been suggested that timing of catheter insertion is important with Barrington, Priestly, Royse, Nygard, Jideus, Berendes, Chakravarthy and Sanchez advocating insertion the day before surgery and Scott, Turfrey, Fillinger, Salvi and Pastor on the day of surgery. Finally Scott et al recommended that TEA should only be used in an institution with immediate MRI availability to facilitate rapid diagnosis of epidural haematoma and also recognised the importance of using anaesthetic drugs with rapid offsets to facilitate early neurological assessment.

TEA in combination with general anaesthesia results in more rapid extubation and significantly better pain relief in patients undergoing cardiac surgery. There may also be a lower incidence of respiratory, cardiovascular, renal and psychological complications although the length of hospital stay is not affected. The optimal drug regime has probably not been established. Whilst there is a theoretical risk of epidural haematoma and a few have been reported the risks appear small on the basis of the evidence available and are minimised by the use of appropriate well-documented basic sensible precautions to ensure normal haemostasis prior to catheter insertion and removal.

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2. Scott NB, Turfrey DJ, Ray DA, Nzewi O, Sutcliffe NP, Lal AB, Norrie J, Nagels WJ, Ramayya GP.. A prospective randomized study of the potential benefits of thoracic epidural anesthesia and analgesia in patients undergoing coronary artery bypass grafting.
3. Turfrey DJ, Ray DA, Sutcliffe NP, Ramayya P, Kenny GN, Scott NB.. Thoracic epidural anaesthesia for coronary artery bypass graft surgery. Effects on postoperative complications.
4. Barrington MJ, Kluger R, Watson R, Scott DA, Harris KJ.. Epidural anesthesia for coronary artery bypass surgery compared with general anesthesia alone does not reduce biochemical markers of myocardial damage.
5. Priestley MC, Cope L, Halliwell R, Gibson P, Chard RB, Skinner M, Klineberg PL.. Thoracic epidural anesthesia for cardiac surgery: the effects on tracheal intubation time and length of hospital stay.
6. Royse C, Royse A, Soeding P, Blake D, Pang J.. Prospective randomized trial of high thoracic epidural analgesia for coronary artery bypass surgery.
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