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Three Part Question

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

Clinical Scenario

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.

Search Strategy

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]

Search Outcome

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).

Relevant Paper(s)

Author, date and country	Patient group	Study type (level of evidence)	Outcomes	Key results	Study Weaknesses
Liu et al, 2004, USA	Meta-analysis of 15 trials enrolling 1178 patients over period 1996 to 1st Jan 2004 obtained from searching Medline, American College of Physicians Journal Club, Cochrane database of Systematic reviews, and Database of Abstracts of Reviews of Effects	Meta-analysis (level 1a)	Odds of death	TEA 0.7% vs. GA 0.3% OR 1.56 (0.35–6.91) P=0.56. 1178 pts	Almost all the RCT's were small including 3 studies with <20 participants Pooled numbers still too few to determine effects on myocardial ischaemia and mortality 7 studies reported in the table below not part of the meta-analysis
			Odds of MI	TEA 2.3% vs. GA 3.4% OR 0.74 (0.34–1.59); P=0.44. 1026 pts
			Odds of suffering dysrhythmias (AF or tachycardia)	TEA 17.8% vs. GA 30% OR 0.52 (0.29–0.93) P=0.03. 913 pts
			Odds of pulmonary complications	TEA 17.2% vs. GA 30.3% OR 0.41 (0.27–0.60) P<0.00001. 644 pts
			Odds of time to tracheal extubation (hours)	TEA 6.9 h vs. GA 10.4 h Mean Difference –4.5 (–7 to –2) P=0.0005. 905 pts
			Odds of postoperative pain (Visual analogue scale)	TEA 12.4 mm vs. GA 19.6 mm Mean Difference –7.8 mm; (–15 to –0.6); P=0.03. 392 pts
			Incidence of neurological injury	No cases of spinal/epidural haematoma
Scott et al, 2001, UK	420 patients undergoing elective CABG surgery Standard GA with 72hrs narcotic analgesia v standard GA with 96hrs TEA Elective CABG pts with normal preoperative coagulation status Epidurals inserted at T2/3 or T3/4 in OR immediately preoperatively – operation postponed if "bloody tap" obtained Bilateral T1-T10 block instituted with Bupivacaine 0.5% and maintained with Bupivacaine / Clonidine infusion perioperatively +/- additional Bupivacaine top-ups postop.	PRCT (level 1b)	Time to extubation (to achieve standard unit extubation criteria)	51/206 (25%) TEA vs.11/202 (5.5%) GA extubated within 4 h (P<0.0001)	Avoidance of Beta-blockade during study period unless clinically indicated might be confounding factor in development of dysrhythmias 73/202 (36%) GA v 100/202 (49%) TEA had no preoperative complications p=0.012
			Incidence of new supraventricular arrhythmias	21/206 (10.2 %) TEA vs. 45/202 (22.3%) GA P=0.001
			Incidence of proven respiratory tract infection	31/206 (15.3%) TEA vs. 59/202 (29.2%) GA group developed LRTIs P=0.0007
			Maximal inspiratory lung volume (ILV)-subset analysis of 47 TEA & 46 GA pts	Maximal ILV better in TEA vs. GA group – 985± 326 ml vs. 733±208 ml; P<0.0001
			Overall any complication rate in 1st 5 days postoperatively	84/206 (40.8%) TEA vs. 108/202 (53.5%) GA P=0.011
			Neurological sequelae	No permanent neurological complications associated with use of TEA
Turfey et al, 1997, UK	218 consecutive patients undergoing CABG surgery 118/218 Standard GA+target-controlled Alfentanil for 1st 24hrs post-op, then IV PCA Morphine for 48hrs 100/218 Standard GA + TEA. TEA instituted with 0.5% Bupivacaine and maintained with a Bupivacaine / Clonidine infusion Epidurals inserted immediately before induction of anaesthesia and run for 5 days postoperatively TEA not used in presence of abnormal coagulation (Aspirin only not a contraindication)	Retrospective Cohort (level 2b)	Time to tracheal extubation	21% TEA vs. 2% GA extubated within 1 h of surgery (P<0.002)	Not a randomised study Decision to use TEA based on Anaesthetist's preference Study from same unit as that of Scott et al
			Incidence of postoperative arrhythmias	18/100 (18%) TEA vs. 38/118 (32%) GA (P=0.02)
			Incidence of respiratory complication	16% TEA vs. 21% GA pts P=NS
			Other complications	No significant differences in incidence of other renal, GI or haematological complication. No significant difference in cardiac complications, difference in IABP use/ no VAD use. No difference in inotrope use
			Incidence of neurolgical complication	6/100 (6%) TEA vs. 9/118 (7.6%). GA pts had neurological complication– not significant. TEA group CNS complications – one leg weakness (no epidural haematoma on MRI)
Barrington et al, 2005, Australia	120 pts undergoing elective CABG surgery Comparison of high thoracic epidural anesthesia / analgesia + general anaesthetic (HTEA) to general anaesthesia only (GA) Pts with abnormal coagulation, recent Aspirin ingestion or evidence of neurological dysfunction excluded from study HTEA group – epidural inserted at T1/2 or T2/3 the day before surgery and established with Ropivacaine / Fentanyl GA group – standard GA with postoperative morphine infusion	PRCT (level 1b)	Time to tracheal extubation	Mean time to extubation 15 min HTEA vs. 430 min GA (P<0.0001) 60% HTEA pts vs. 5% GA pts extubated within 30 min of completion of surgery (P<0.0001) Time to extubation beyond 30 min not significantly different HTEA vs. GA	Significant higher incidence of peripheral vascular & cerebrovasc disease in HTEA v GA group (p=0.016 & 0.002 respectively) Group allocations not masked – might bias towards early extubation
			VAS assessment of postoperative analgesia	HTEA pain scores significantly less than GA scores at all time points with/without coughing
			Cardiac troponin (cTnI) & CK-MB levels preop and 12 and 24 h post-cross-clamp release	cTnI levels HTEA vs. GA – both raised at 12 & 24 h but no significant difference between groups
			12 lead ECGs preop and on postop days 1 & 5 (2 blinded observers)	3/60 (5%) HTEA vs. 5/60 (8.3%) GA pts developed new ECG changes 1/60 (1.6%) HTEA vs. 2/60 (3.3%) GA pts had evidence of transmural MI on basis of ECG but no difference in incidence of myocardial ischaemia on basis of ECG or biochemical criteria
			Neurological sequelae	No neurological complications related to HTEA
Priestley et al, 2005, Australia	100 pts randomised to either standard GA + postop IV Morphine PCA or standard GA + TEA for 48hrs postop, then epidural PCA Meperidine for further 24hrs TEA inserted on night before surgery at T1-T4 and induced with Ropivacaine / Fentanyl. Surgery NOT postponed in presence of "bloody tap" but attempt made to resite elsewhere Exclusions - pre-existing coagulopathy - anticoagulation - potent anti-platelet drugs - systemic / local infection - arthritis of spine with history of associated neurological deficit - cognitive impairment Aspirin & other NSAID's usually discontinued 1 week before surgery but not a contraindication to TEA	PRCT (level 1b)	Time to tracheal extubation	TEA vs GA medians 3.2 vs. 6.7 h (P<0.0001)	Study powered on basis of length of hospital stay Male preponderance in both groups (5-7:1) Decision to discharge made by unblended surgeons Whilst study did not demonstrate earlier discharge in TEA group it did demonstrate earlier discharge of both study TEA & control groups in comparison to non-study pts
			Time to achieve standard mobilisation goal of ability to climb 2 flights of stairs unaided	No significant difference TEA vs GA in time to achieve standard mobilisation goals, criteria for discharge, and actual time to discharge
			Time to achieve standard unit discharge criteria	24% of total cohort discharged on Day 4 & 33% on Day 5 compared to 2% & 18 of pts outwith study population
			Actual time to discharge	No significant differences
			Respiratory function	No significant differences
			Atrial fibrillation	10/50 (20%)GA vs. 11/50 (22%) TEA developed AF
			Postoperative pain VAS scores	Analgesia better in TEA group at rest and during coughing but statistically significant during 1st postop 24 h only - 16/50 (32%) GA vs 6/50 (12%) TEA had VAS >40 mm (P=0.015)
			TEA complications	No major complications related to epidural technique 4/50 (8%) epidurals 'failed' 3/50 (6%) TEA vs 2/50 (4%) GA pts developed postop urinary catheterisation
Royse et al, 2003, Australia	80 CABG pts randomised to GA+high TEA (HTEA) or GA+PCA Morphine HTEA inserted at T1/2 or T2/3 on night before surgery. Induced & maintained with Ropivacaine / Fentanyl until 3rd postop day	PRCT (level 1b)	Pain on 1st and 2nd postop days assessed by 10cm VAS at rest and with coughing	Significantly better pain scores with HTEA vs GA (mean cm scores): Day 1 Rest 0.02 vs. 0.8 P=0.032. Day 1 Cough 1.2 vs. 4.4 P<0.001 Day 2 Rest 0.1 vs. 1.2 P=0.044 Day 2 Cough 1.5 vs. 3.6 P=0.005
			Post operative ventilation/hospital stay	HTEA vs. GA 2.6± 2.5 h vs. 5.4±3.1 h (P<0.001) Length of ITU/hospital stay – no significant difference HTEA vs. GA Postop creatinine/atrial fibrillation – no significant difference HTEA vs. GA
			Assessment of lung function - preop and daily spirometry and SpO2 on air - arterial blood gases on postop day 1	Lung function lower both groups - – O2 higher in HTEA than GA group; P=0.041 (P=0.041 corrected)1 – PEFR higher in HTEA than GA group on all days incl Day 3 when epidural discontinued P=0.001 (0.003 corrected). 1. P values corrected using technique to test 6 hypotheses
Nygard et al, 2004, Denmark	163 pts scheduled for CABG surgery 2x2 factorial study to compare high TEA, Amiodarone therapy or both against control in preventing postop AF Exclusions - recent use of Amiodarone - Amiodarone toxicity - Warfarin therapy or coagulopathy - use of antidysrhythmics (other than Beta blockers, digoxin & calcium-channel blockers) Group E - high TEA Group A - Amiodarone Group E+A - high TEA + Amiodarone Group C - Control Epidural groups - epidural inserted at T1-3 the day before surgery and maintained for 96hrs. Initiated with Bupivacaine & maintained with Bupivacaine / Morphine Amiodarone groups - 1800mg orally, then IV infusion commencing after induction of anaesthesia for 3 days - 900mg/24hrs All patients received standard GA and non-TEA pts IV morphine analgesia 5 days of continuous Holter monitoring - automated & blinded manual reporting	PRCT (level 1b)	Incidence of new onset AF - 5 min	Group E - 22/44 (50%). Group A - 10/36 (27.8%). Group E+A - 10/35 (28.6%). Group C - 20/48 (41.7%). No signif difference in AF incidence between TEA (E & E +A) groups and non-TEA (A & C) groups P=0.538 No significant difference in incidence of AF requiring treatment in TEA E & E+A) vs. non-TEA (A & C) groups - 28/79 (35%; 95% CI 25 - 47%) vs. 25/84 (30% 95% CI 20 - 41%) P=0.66
Jideus et al, 2001, Sweden	141 patients undergoing elective CABG 45/141 randomly selected for standardised GA with intraoperative & postoperative TEA; 96/141 control group TEA inserted at T2/3, T3/4 or T4/5 the day before surgery and established with Bupivacaine. TEA postoperatively maintained with Bupivacaine / Sufentanil for 96hrs or until onset of sustained AF 96/141 control patients ¡V standardised GA only with postop Ketobemidone analgesia. Both groups monitored with Holters for 24hrs preop & 96hrs postop	PRCT (level 1b)	Incidence of sustained AF >30 s on Holter	13/41 (31.7%) TEA vs. 29/80 (36.3%) GA (P=0.77) Onset time of AF 1.9 days (TEA) vs. 2.2 days (GA) post-op P=0.23	Lack of information about randomisation process Control group twice the size of treatment group Exclusions in control group may have affected AF outcomes Beta-blockers more likely to be withdrawn in TEA group ¡V might affect AF outcomes
			Pre and postop levels of Neuropeptide Y (NPY), Chromogranin A (CgA), Chromogranin B (CgB) Pancreatic polypeptide (PP) Epinephrine Norepinephrine	Postop NPY levels significantly lower in TEA vs. GA group(P=0.002 vs. P=0.60). CgA & CgB levels unchanged postop in both groups PP significantly lower in both TEA & GA groups postop (P=0.04 & P=0.0001). Raised Epinephrine in both groups in day 1 though less marked in TEA group (TEA P=0.002 vs. GA P<0.001). Pre & postop Norepinephrine levels unchanged in TEA group (P=0.73) but significant increase in GA group (P=0.002)
Salvi et al, 2004, Italy	106 consecutive pts undergoing off-pump surgery under combined TEA & general anaesthesia TEA performed immediately prior to anaesthesia at T1/2 or T2/3 and induced and maintained with Ropivacaine / Sufentanil to block C7/T1 to T6/T7. Catheter removed on 3rd postop day Exclusion criteria - abnormal coag studies - abnormal platelet counts - recent anticoagulation / thrombolysis - coagulation disorders - neuroaxial pathology - recent acute infarct	Retrospective cohort (level 2b)	Time to extubation	Mean time to extubation 4.6± 2.9 h (median 4; range 0.5–12 h)	Uncontrolled cohort group – no comparison group TEA unsuccessful in 2/106 (1.8%) pts Bloody tap in 1/106 (0.9%) pts No dural taps
			Length of ITU stay	Mean ITU stay 1.5± 0.8 days (median 1.0; range 0.5–6 days)
			Incidence of MI	4/106 (3.8%) pts presented with signs of myocardial ischaemia – attenuated/abolished by institution of TEA
			Incidence of AF	11/206 (10.6%) developed AF during ITU stay
			Assessment of pain using Visual analogue score	Good analgesia at rest and with coughing
			Neurological complications	1/106 (0.9%) pts developed postop paraplegia - emergency MRI excluded 2° to spinal/epidural haematoma
Chakravarthy et al, 2005, India	2113 adults undergoing cardiac surgery (CABG, valve surgery, congenital surgery) under general + epidural anaesthesia over 13 year period Epidural catheter inserted at C7 to T3 level day evening before surgery in patients with normal coagulation studies and platelet number, no anti-platelet therapy for 1 week and heparin discontinuation for 6-12 hours pre-insertion. Epidural avoided in patients on anti-platelet therapy, with coagulation problems, with previous surgery to cervical or thoracic spine or local infection. Evolving epidural regime over time using combinations of Lidocaine+/-Epinephrine / Bupivacaine / Morphine / Buprenorphine / Fentanyl	Cohort (level 2b)	Dural puncture	19/2224 (0.85%) – unable to ID epidural space/insert catheter –18/19 – dural puncture –10/18 resited successfully 22/2224 (0.98%) –haemorrhagic tap –12/22 resited successfully 2113 epidurals performed	No outcome parameters Audit designed to look at complications, not outcomes No standard Epidural or GA regime – regime evolved over study period
			Complications	4/2113 – develpoed temporary neurological deficits (transient monoplegias) of up to 24 h which recovered on withdrawal/removal of epidural catheter No other neurological sequelae
Sanchez et al, 1998, Denmark	571 consecutive pts scheduled for CABG over 2 year period Pts not given epidural if on Warfarin; with a prothrombin-proconvertin<50%; or on Aspirin within last 7 days Epidural inserted day before surgery at T1-T3 level. Induced with Bupivacaine & maintained with Bupivacaine / Fentanyl. Standard GA	Cohort (level 2b)	Extubation	Median time to extubation 345 min (range 75–1305 min)	13/571 (2%) epidurals abandoned - 12 uncertain blocks + one unsuccessful catheter placement 558/571 (98%) epidurals successful 1/558 dural puncture – surgery postponed. After 1 day without complication, epidural resited and surgery proceeded 403/558 (72%) on antiplatelet medication
			ITU stay	Median duration of ITU stay 1 day (range 1–13 days) 445/558 (80%) epidurals left for 4–5 days
			Complications	No documented spinal haematomas causing neurolgoical symptoms. No severe radiating back pains. No unexplained/progressive neurological deficits
Pastor et al, 2003, Spain	714 pts undergoing CABG under combined TEA + standard GA over 7yr period TEA inserted between T1-T3 immediately preop & induced and maintained with Bupivacaine or Ropivacaine periop & Ropivacaine / Fentanyl postop. Inclusion criteria - APTT<45 secs - PT (INR) < 1.5 - Platelets > 80,000/ìl - adequate (7 days ) preop suspension of aspirin & clopidigrol Exclusion criteria - pre-existing neurological disorder - failed block - infection at puncture site Technical criteria - max 3 attempts at TEA - midline approach - TEA at least 60 mins before heparinisation - MRI / neurosurgery availability TEA usually terminated at 4 days - normal coagulation - before therapeutic anticoagulation - >12hrs after last but >4hrs before next dose of LMW heparin if used	Prospective cohort (level 2b)	Technical complications of TEA	6/714 (0.84%) dural punctures, no complaints of pain/ paraesthesia; no 'bloody taps' 6/6 (100%) dural punctures successfully resited elsewhere. No postop complications in this group	Observational study designed to confirm that adherence to standard safety measures adverts risk of epidural haematoma No comparison of TEA group to control group
			Time to extubation (standard unit criteria)	Median time to extubation 0 h (0–168) 496/714 (75.3%) extubated in the OR
			Length of ITU stay	Median length of ITU stay 48 h (22–456 h)
			Length of hospital stay	Median length of hospital stay 8 days (3–121)
			General morbidity and mortality	26/714 (3.6%) pts required, prolonged IPPV, reintubation or tracheostomy
			Complications of TEA	3/714 (0.42%) awoke with suspicious motor findings and underwent MRI scanning No evidence of epidural haematoma or sub-acute/chronic space occupying processes
Ho et al, 2000, Hong Kong	4583 patients undergoing cardiac surgery utilising TEA in period up to 1999 reported in previously published trials Assessment of risk of epidural haematoma / spinal injury using Hanley & Lippman-Hand mathematical modelling technique	Cohort (level 2b)	Mathematical calculation of statistical risk of epidural haematoma / spinal injury	Risk of spinal injury from epidural haematoma during TEA between 1:150,000 and 1:1,500 (95% confidence) and up to 1:1,000 (99% confidence)	Remains a mathematical estimation
Berendes et al, 2003, Germany	73 pts scheduled for CABG surgery randomised to GA only (control) or GA+TEA TEA inserted day before surgery at C7/T1 level & initiated with Bupivacaine 0.5% & Sufentanil and maintained with Bupivacaine Exclusions - abnormal coagulation - renal insufficiency - ventricular dysfunction (EF<50%) - valvular surgery - heart failure	PRCT (level 1b)	Regional LV function by transoesophageal echo (TOE)	37/73 GA only vs. 36/73 GA+ Postop LV function scores significantly better in TEA vs. GA pts: 0.78 vs. 0.38; P<0.05	Pts with pre-existing ventricular dysfunction excluded Presentation of TOE, ANP & BNP graphical with little absolute numerical data Although 2 year mortality a 2° outcome study not powered to detect significant difference
			Pre & postop cardiac troponin I	Peak Cardiac Troponin I significantly less in TEA vs. GA pts 1.6 vs. 5.7 ng/ml; P<0.05
			Pre, intra & postop Atrial & Brain natriuretic peptide	ANP maximally raised during reperfusion after cross-clamping – TEA raised significantly less than GA increase (98 vs. 211 ng/ml; P=0.03) BNP increase 6 h post-ITU admission & peaked 24 h postop – TEA significantly attenuated BNP peak – mean BNP peak TEA vs. GA 108 vs. 189 ng/ml (P=0.01)
			Extubation time	Mean time to extubation 3.4 vs. 9.2 h
			Complications	No complications related to TEA; No other significant complications
Filinger et al, 2002, Lebanon	60 pts undergoing cardiac surgery Excluded if any contraindication to TEA (heparin, warfarin, coagulopathy, local/systemic infection) 30/60 GA+TEA Epidural inserted immediately before induction of anaesthesia and induced with morphine/bupivacaine 30/60 GA+postop IVI Morphine	PRCT (level 1b)	Time to tracheal extubation	Time to tracheal extubation GA vs. TEA 9.5 vs. 10.7 h (P=0.49)	Study powered using total hospital costs as proxy for hospital outcome
			Duration of ITU stay	ITU stay GA vs. TEA 30 vs. 31.7 h (P=0.84) Hospital stay GA vs. TEA 160 vs. 156 h (P=0.84)
			Duration of hospital stay	Hospital stay GA vs. TEA 160 vs. 156 h (P=0.84)
			Pain control using 100mm VASs	Pain control on 1st postop day - no significant difference between GA and TEA groups
			Urinary free cortisol	Urinary free cortisol GA vs. TEA 120 vs. 150 µg/dl (P=0.25)
			Total hospital charges	Total charges GA vs. TEA $36,955 vs. $40,026 (P=0.20
			Cardiopulmonary complication rate	20/30 (67%) GA vs. 30/30 (100%) TEA group required catecholamines post-CPB (P=0.0005) Incidence of AF 23% in both groups No difference in incidence of ischaemia between groups 9/30 (30%) GA developed 12 'complications'; 12/30 (40%) TEA developed 17 'complications' No neurological sequelae related to TEA

Comment(s)

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.

Clinical Bottom Line

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.

References

1. Liu SS, Block BM, Wu CL. Effects of perioperative central neuroaxial analgesia on outcome after coronary artery bypass surgery: a meta-analysis. Anesthesiology 2004; 101: 153-61
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. Anesthesia & Analgesia. 2001; 93: 528-35.
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. Anaesthesia 1997; 52: 1090-5.
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. Anesthesia & Analgesia 2005; 100: 921-8.
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