J Ayub Med Coll Abbottabad 2004;16(2)
EFFECTIVENESS OF COMBINED THORACIC EPIDURAL AND
LIGHT
GENERAL ANAESTHESIA IN PATIENTS UNDERGOING NON-CARDIAC THORACIC SURGERY
Khawaja Kamal Nasir, Faraz Mansoor, Imran Mohammad Khan, Ayaz-bin-Zafar, Safdar Ali, Jawad Ahmad
Department of
Anesthesiology,
Background: The specialty of thoracic anaesthesia has emerged as a scientifically based
discipline just 30 years back. At the start of the 20th century empyema and tuberculosis were the main indications for the
thoracic surgery. Later on with the introduction of antibiotics lung
malignancies were more commonly operated. Recent resurgence of tuberculosis and
associated medical illnesses put these patients in high risk for surgery and anaesthesia, necessitating introduction of more skilful
approach. The objective of this study was to evaluate the effectiveness of
combined thoracic epidural anaesthesia and light
general anaesthesia in patients undergoing
non-cardiac thoracic surgery. Methods:
This study was conducted at the department of Anesthesia and Intensive care,
Pakistan Institute of Medical Sciences,
Key Words: Non-cardiac thoracic surgery. Thoracic
epidural. Epidural tramadol.
INTRODUCTION
The entire peri-operative period is stressful, characterized by
complex autonomic, hormonal and physiological perturbations. Patients
undergoing thoracic surgery have associated cardiac and respiratory
disturbances, which pose them to increase risk.1 Pulmonary
dysfunctions begin with incision and remain diminished for 7—14 days
postoperatively.2 Measures are required to decrease the morbidity
and mortality in this group of patient.
A comprehensive preoperative
evaluation is very crucial, because this is the time when important decisions
are being made by the clinician, patient and his family.
Thoracic epidural
combined with light general anaesthesia is an
established anesthetic management for thoracic surgery. It is well known in
literature that patients with preexisting impaired oxygenation have good oxygen
content and blood pressure when combined thoracic epidural and general anaesthesia is used.3 It is also well documented
that inhaled anesthetics, mechanical ventilation, paralysis and opioids all contribute to reduce pulmonary function. These
harmful effects of general anaesthesia can be reduced
with the help of employing thoracic epidural with low doses of general anaesthetics.
Majority of these
patients also have coexisting cardiovascular problems. Enhanced sympathetic
activity during perioperative stress can result in ischaemia and cardiac arrhythmias; thoracic epidural blocks
the sympathetic out-flow to heart and thus provide a good control against the
development of such lethal cardiac events.4-8 Moreover the incidence
of post thoracotomy pain is 62%.9 Employing
thoracic epidural can decrease this high incidence.
MATERIAL AND
METHODS
Ten patients of ASA grade I-III, < 68 years of
age undergoing elective non-cardiac thoracic surgery were included in the study
at Pakistan
Patients with
chest trauma, history of allergy to local anaesthetics,
low platelet count (<100,000), abnormal coagulation profile, medicinal
anticoagulation9aspirin, and non steroidal anti-inflammatory are not
contraindications). Patients with bony spinal abnormalities and neurological
disorders were also excluded from the study.
A detailed
preoperative assessment included; history followed by relevant investigations.
Every patient was assessed preoperatively for epidural catheter placement. On
arrival in the operation theatre, two 16 gauge intravenous cannulas
and electrocardiograph leads were placed (Kion,
Siemens SC7000. monitor was used to monitor continuous ECG, NIBP (non-invasive
blood pressure monitoring), SaO2 (oxygen saturation) and inspiratory and expiratory anaesthetic
gases. Urine out put and central venous pressure was recorded after every 15
minutes. 16-gauge double lumen central venous line (Certofix
Duo S B720, B. Braun) were placed through subclavian
vein of the operative side.
Epidural catheter was placed at T5/6 interspace about 20 to 30 minutes before the induction of
general anaesthesia. 18 gauge Tuohy
needle (1 Perifix 401 Filter set (loss of
resistance), B. Braun) was introduced and epidural space identified with loss
of resistance to air technique. Seven milliliters of inj.
Bupivacaine 0.375% was injected after test dose of 3
ml lignocaine 2% with adrenaline
1: 200,000. Patients were premedicated with pethidine 50
mg. Sleep dose of Thiopentone sodium was used for
induction. Tracheal intubation was facilitated with inj. Atracurium in the dose of
0.5 mg/kg. Muscle paralysis was maintained by appropriate doses of atracurium for the entire procedure. A left sided
double-lumen endotracheal tube (Broncho-cath
TM Left) was used for one lung ventilation. Position of the tube was
confirmed with the help of fibreoptic bronchoscope.
Anesthesia was maintained with thoracic epidural combined with low dose
concentration 0.3---0.5 vol % of isoflurane
(end-tidal) in a mixture of O2 and N2O and intermittent positive pressure
ventilation. Blood loss exceeding 500ml was replaced with whole blood.
Postoperatively, epidural
Bupivacaine was administered in a dose of 0.25%
four-hourly and tramadol 50 mg 6 hourly as guided by
the sedation score. UCL Hospital Sedation Score was used to assess the level of
pain control and sedation of the patient. Awake and uncomfortable patient was
labeled +2, awake and calm +1 and aroused by voice and calm was labeled 0.
RESULTS
Out of total 10 patients, two of our patients were
smokers and they were preoperatively counseled and bronchodilators prescribed.
Duration of the procedure ranged from three to five hours. One lung ventilation
was required in eight (80%) patients and it was achieved with the use of left
sided double lumen tube in all cases. The hypotension recorded after epidural
injection of local anaesthetic was within 20% of the
base line. Hypoxemia occurred in three (30%) patients and it was treated
effectively by increasing the inspired oxygen concentration. None of these
patients required the need for dependent lung PEEP (positive end expiratory
pressure) or non-ventilated lung CPAP (continuous positive airway pressure).
All patients received blood transfusion from loss greater than 500 ml. Only one
patient developed life threatening ventricular fibrillation during the
procedure, remaining nine (90%) patients had no such problem during intra
operative period. Urine out put remained greater than 60ml in 90% of patients.
80% of the patients were extubated in the operation
theatre. One patient died in the operation theatre due to massive and
uncontrolled blood loss. None of our patient required any additional analgesia
during surgery.
According to our
department protocol all patients were shifted to intensive care unit after the
completion of surgery. ICU stays ranged from two days to five days. During
their ICU stay none of our patient developed life threatening hypoxemia
(<90%), respiratory dysfunctions (tachypnoea,
hypoventilation, inability to cough, and abnormal arterial blood gases), Only
one patient developed supraventricular tachycardia,
which was managed by non-pharmacological method (carotid massage). No other
major organ dysfunctions were observed. Average dose of tramadol
injected through epidural space was 300-mg/24 hrs. Bupivacaine
in a dose of 0.25% was used after every four hours. Two (20%) patients demanded
supplementary analgesia that was provided by inj. Pethidine in a dose of 10 mg on as required basis guided by
the sedation score.
Table-1: Frequency of Complications
Complications
|
Frequency
|
|
Intraoperative Hypoxemia |
30% |
|
Intraoperative ventricular fibrillations |
10% |
|
Postoperative arrhythmias |
10% |
|
Deaths |
10% |
|
Massive Bleeding |
10% |
Table-2: Summary of advantages of
combined thoracic epidural and light general anaesthesia
|
Advantages |
Frequency |
Intraoperative hypotension
|
10% |
|
Intraoperative hypoxemia |
30% |
|
PEEP |
0% |
|
CPAP |
0% |
|
Intraoperative VF |
10% |
|
Extubation in O R |
80% |
|
Postoperative Hypoxemia |
0% |
|
Postoperative Arrhythmias |
10% |
|
Postop additional analgesia |
20% |
|
Successful epidural placement |
100% |
DISCUSSION
The number of patients undergoing non-cardiac
thoracic surgery has increased due to the resurgence of tuberculosis and
increased incidence of lung cancer in both sexes. At
the same time it requires sophisticated anaesthetic
and surgical techniques to decrease the morbidity and mortality in these
patients.
Thoracic epidural
combined with general anaesthesia is an established
anesthetic technique for thoracic surgery. Use of preemptive analgesia in the
form of thoracic epidural was very beneficial. Neustein
and colleagues employed preemptive epidural analgesia for thoracic surgery and
discovered its hidden benefits.9 Moreover, the preoperatively
initiated thoracic epidural has the most satisfying results in controlling postthoraco-tomy pain in the acute and long-term period,
and is associated with a decreased incidence of chronic pain compared with
postoperative epidural or opioids analgesia. We
recorded a lesser magnitude of hypotension with the administration of local anaesthetic at thoracic epidural level. This was because
only upper thoracic segments were blocked, sparing the caudal-sympathetic
nervous system. This is supported by the study carried out by Magnusdati and colleagues.10 Thoracic epidural
when combined with general anaesthesia decreases the
dose requirements of inhalational agents. This
decrease in inhalational agent dose have a very good
impact in decreasing the frequency of hypoxemic episodes in our patients
because of the preservation of reflex pulmonary vasoconstriction when one lung
ventilation was instituted.3
It was possible
to extubate 80% of our patients in the operation
theatre. These early extubations can be attributed to
small doses of opioids and low concentrations of inhalational agents. Thoracic epidural added advantage that
made it possible. It is a well-known fact that phrenic
nerve function is inhibited in thoracic surgery and use of local anaesthetics through epidural route can improve its
function. This is supported by the study carried out by Fractacci,
who reported improvement in diaphragm function in thoracic surgery with the use
of thoracic epidural.3 We observed decreased frequency of cardiac arrhythmias and ischaemic
episodes in our patients. When patients undergo major surgery, it puts them
under stress. This results in sympathetic over activity, which can lead to
cardiac arrhythmias and ischaemic episodes. Study
carried out by
There were no
major complications observed in the intensive care suite. We employed epidural
technique because of its documented facts in patients who have coexisting
obstructive pulmonary disease along with lung cancer. A similar study carried
by Shuman showed excellent results in patients where thoracic epidural was
employed for thoracic surgery.13 Our results are similar to study
carried out by Tenling in regard to improved
ventilation-perfusion when combined thoracic and light general anaesthesia was employed.14
We used one (m-methylphenyl)-2-(dimethylaminoethyl)-cyclohexan-1-01
(tramadol; tramal) in
combination with local anaesthetic bupivacaine for postoperative pain relief. The efficacy of tramadol for pain relief through epidural route is well
established and when combined with local anaesthetics,
they augment each other actions.15
CONCLUSION AND RECOMMENDATIONS
It is suggested that
thoracic epidural should be used in combination with general anaesthesia for non-cardiac thoracic surgery. People
generally think that the complications associated with the insertion of
thoracic epidural are greater than lumbar approach. Recent survey suggests that
placement of epidural catheter at thoracic level do not confer higher risk than
placement at lumbar level.16 In contrast to the exacerbation of
postoperative pulmonary dysfunction seen with general anaesthesia,
thoracic epidural has minimal effect on pulmonary function and may offset
detrimental changes in pulmonary function induced by general anaesthesia. The combined use of the drugs reduces the dose
requirements of individual agents.
Many residency
programs do not teach the insertion of thoracic epidural technique, and
postgraduates are, therefore uncomfortable with the procedure, preferring
instead the more familiar lumbar route. So the author think that the combined
use of the general and thoracic epidural anaesthesia
is a good approach in improving the out-come of patients undergoing non-cardiac
thoracic surgery. The general concept of analgesia is very true but we can also
achieve some hidden benefits.
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Address For Correspondence:
Dr Faraz Mansoor, Department of Anesthesiology, Pakistan Institute of
Medical Sciences,
Email: mansoor_faraz@hotmail.com