Br. J. Anaesth. (1975), 47, 48
POSTOPERATIVE EXTRADURAL ANALGESIA FOLLOWING THORACIC SURGERY: A FEASIBILITY STUDY D. P. G. GRIFFITHS, A. W. DIAMOND AND J. D. CAMERON SUMMARY
There have been a number of investigations into the use of extradural analgesia following abdominal surgery (Simpson et al., 1961; Spence and Smith, 1971; Holmdahl et al., 1972). In obstetric practice, the technique is gaining popularity for pain relief during labour. However, its use for pain relief following thoracic surgery has not been evaluated. This study assesses the feasibility, side effects and complications of providing pain relief using an infusion of bupivacaine into the extradural space following the operation of thoracotomy for carcinoma of the lung. METHOD
Patients studied. Patients receiving extradural analgesia need constant supervision which, at this hospital, is available only in the Intensive Care Unit. The first patient on a routine thoracic surgical operation list received an extradural block when an Intensive Care bed was available. Seventeen males and three females, in the age range 46-70 years, who were undergoing thoracotomy for presumed carcinoma of the lung, were studied. Patients over 70 years of age or suffering from cardiac disease, hypertension, neurological disorder or skin sepsis were excluded. Respiratory function assessment. The patients were assessed before operation on the basis of clinical history, physical examination, chest x-ray, and simple respiratory function tests
which included blood gas analysis. This assessment was repeated at 24 hours, 48 hours and 10 days after operation. Arterial blood was taken before the other respiratory function tests were performed and was stored in melting ice prior to gas analysis. Peak flow was measured using a Wright peak flow meter. Forced vital capacity (FVC) and forced expiratory volume in 1 sec (FEVi) were measured, while the patient was sitting in bed at an angle of 45°, using a Vitalograph spirometer. The best results from three tests were taken and corrected to BTPS. The ratio FEV,:FVC was calculated. Oxygen tension was measured using a Po a sensitive electrode, carbon dioxide using a Stowe-Severinghaus Pco3 electrode (E.I.L. 48c or I.L. 213 blood gas analysers). The results were corrected for temperature difference between the patient and the electrode using the nomograms of Kelman and Nunn (1966). EXTRADURAL ANALGESIA
Operative management. All the patients were premedicated with nitrazepam 10 mg and droperidol 10-20 mg given orally 2 hours before surgery. Anaesthesia was induced with thiopentone followed by alcuronium injected i.v. After insertion of a Magill cuffed orotracheal tube, anaesthesia was maintained with 50% nitrous oxide in oxygen, supplemented with halothane and D. P. G. GRIFFITHS, F.F.A.R.C.S.; A. W. DIAMOND, F.F.AJLC.S.; J. D. CAMERON, B.SC., M.SC.; Frenchay
Hospital, Bristol, BS16 1LE. All correspondence to A.WJD.
Downloaded from http://bja.oxfordjournals.org/ at University of California, Santa Cruz on March 11, 2015
The feasibility of providing postoperative analgesia using thoracic extradural blockade following thoracotomy has been assessed. Extradural block was produced by intermittent injections of 0.5% bupivacaine with adrenaline 1:200,000 or a continuous infusion of 0.25% or 0.125% bupivacaine. The only toxic symptom was drowsiness which was most frequent after a continuous infusion of 0.25% bupivacaine and with arterial plasma bupivacaine concentrations above 1.5 //g/ml. Arterial hypotension was a troublesome complication with all techniques although stability of arterial pressure was more easily achieved with a continuous infusion technique. However, this produced a high incidence of urinary retention. Practical aspects and effectiveness of providing extradural analgesia in patients following thoracotomy are discussed.
49
EXTRADURAL ANALGESIA FOLLOWING THORACIC SURGERY
Management. In the recovery room, the adequacy of the extradural block was assessed by pinprick testing. The extent of the block, the dose of bupivacaine, and the arterial pressure measurements were recorded following each injection of bupivacaine. The first 10 patients were given intermittent injections of 0.5 % bupivacaine with adrenaline 1:200,000 when the segmental block was found to be inadequate, either as a result of pinprick testing or a complaint of pain from the patient. The second 10 patients were given either a continuous infusion of 0.25% bupivacaine from a powered syringe (five patients) or 0.125% bupivacaine (125 ml of bupivacaine 0.5% in 375 ml of 0.9% saline) delivered from a Holter pump (Extra Corporeal Medical Specialties Inc.) (five patients) at a rate to maintain an adequate segmental block. The initial infusion rate was half the recommended mayi'mnm rate of 0.5 mg/kg/hr: that is approximately 5 drops per min of 0.125% bupivacaine solution. Bolus injections of 5-8 ml of 0.25% bupivacaine were given if the block was found to be inadequate. The patients were transferred to the Intensive Care Unit where the block was continued for 48 hours. An anaesthetist remained in the Unit throughout and was available to supervise the management of the block and deal with any complication that might arise. For prophylaxis all patients were given antibiotics for 48 hours before operation and for 5 days after operation. A vigorous regime of physiotherapy was instituted in the postoperative period.
Pain assessment. On the 10th postoperative day, all patients still accessible for interview were asked whether they remembered experiencing any pain in the 48 hours following the operation and, if so, to grade it as absent, slight, moderate or severe. Estimation of bupivacaine concentrations. In eight patients, arterial samples were taken for plasma bupivacaine estimation at 6, 24 and 48 hours following the start of the extradural block. Bupivacaine was extracted from plasma as described by Reynolds and Beckett (1968) except that cyproheptadine was used as the internal standard in place of methadone. Cnromatography was carried out using a Pye Unicam 104 Gas Chromatograph with a flame ionization detector. The column was 0.9 m long, 0.63 cm o.d. glass, packed with 3% OV17 on Gas Chrom Q (100-120 mesh) (Phase Separations Ltd, Queensferry, Flints.). The oven temperature was 220°C and the injection point temperature 270 °C. The carrier gas was nitrogen at a flow rate of 50 ml/min, hydrogen pressure 15 Lb./sq.in. and sensitivity 2-5 X10"10 Af.s.d. The concentration of bupivacaine in the patient's plasma was found by the calculation of peak height ratios of bupivacaine to cyproheptadine and relating these to a calibration curve. RESULTS
The sex and age of the patients and the type of operation are shown in table I. The skin incisions were made through the second to 8th thoracic dermatomes, the intercostal drain emerging from the 9th or 10th interspace. Postoperative pain relief (table II). At 10 days, 15 patients were available for interview: seven of the "intermittent" group and eight of the "continuous" group. 47% of the patients stated that they had been pain-free, 33% graded their pain as slight, 13% moderate and 7% severe. No patient in the intermittent group graded his pain as moderate or severe. 50% of the patients admitting to pain during the block complained of pain from the intercostal drain site. Table m shows the amount of bupivacaine infused. Those patients who were given a continuous infusion of 0 2 5 % bupivacaine received a mean total dose of 1054.6 mg of bupivacaine, those given 0.125% bupivacaine a mean total dose of 766.4 mg and those given intermittent injections a mean total
Downloaded from http://bja.oxfordjournals.org/ at University of California, Santa Cruz on March 11, 2015
incremental doses of fentanyl. Arterial pressure was measured continuously throughout the operation using a radial artery cannula connected to a Tycos manometer (Zorab, 1969). Before operation and under general anaesthesia, the patients were placed in the lateral position with the diseased side dependent. An extradural cannula was inserted, via a Tuohy needle, through the midline at a suitable space between the second and sixth thoracic spines, and connected to a Swinnex millipore filter by means of a Tuohy-Borst chuck. Following a test dose of 2 ml to eliminate the possibility of a subarachnoid injection 4-6 ml of 0.5% bupivacaine with 1:200,000 adrenaline was injected. When the mean arterial pressure decreased to less than 50 mm Hg, it was restored with a rapid infusion of Hartmann's solution. Atropine 0.6 mg was given when the hypotension was accompanied by bradycardia.
BRITISH JOURNAL OF ANAESTHESIA
50 TABLE I. Sex
Mean age (yr)
M Intermittent extradural 8 (0.5% bupivacaine) Continuous extradural 9 (0.25-0.125% bupivacaine) TABLE II.
Intermittent bupivacaine (0.5% with adrenaline) (10 cases)
Pneumonectomy
±6.6
TABLE IV.
Pain relief.
Respiratory
3
2
4
0
function and results.
Extradural technique Intermittent
Continuous
19.8 0.4
5.7 0.7
163.0 51.0
573.5 156.0
Continuous bupivacaine 0.25% (5 cases)
Mean SD
1054.6 593.0
0.125% (5 cases)
Mean SD
766.4 344.0
dose of 573.5 mg (mean of 9.8 doses of mean volume 5.7 ml). The mean duration of action of each dose in the intermittent group was 163 minutes. The continuous infusion group required a mean of 5.1 bolus doses of bupivacaine to maintain an adequate segmental block. The results of respiratory function tests and blood gas analyses before operation and at 24 and 48 hours and 10 days after operation are shown in table IV. Using the paired f-test for comparison of mean values, all the postoperative values of FEV,, FVC and peak flow were significantly reduced when compared with the preoperative value (P
POSTOPERATIVE EXTRADURAL ANALGESIA FOLLOWING THORACIC SURGERY: A FEASIBILITY STUDY D. P. G. GRIFFITHS, A. W. DIAMOND AND J. D. CAMERON SUMMARY
There have been a number of investigations into the use of extradural analgesia following abdominal surgery (Simpson et al., 1961; Spence and Smith, 1971; Holmdahl et al., 1972). In obstetric practice, the technique is gaining popularity for pain relief during labour. However, its use for pain relief following thoracic surgery has not been evaluated. This study assesses the feasibility, side effects and complications of providing pain relief using an infusion of bupivacaine into the extradural space following the operation of thoracotomy for carcinoma of the lung. METHOD
Patients studied. Patients receiving extradural analgesia need constant supervision which, at this hospital, is available only in the Intensive Care Unit. The first patient on a routine thoracic surgical operation list received an extradural block when an Intensive Care bed was available. Seventeen males and three females, in the age range 46-70 years, who were undergoing thoracotomy for presumed carcinoma of the lung, were studied. Patients over 70 years of age or suffering from cardiac disease, hypertension, neurological disorder or skin sepsis were excluded. Respiratory function assessment. The patients were assessed before operation on the basis of clinical history, physical examination, chest x-ray, and simple respiratory function tests
which included blood gas analysis. This assessment was repeated at 24 hours, 48 hours and 10 days after operation. Arterial blood was taken before the other respiratory function tests were performed and was stored in melting ice prior to gas analysis. Peak flow was measured using a Wright peak flow meter. Forced vital capacity (FVC) and forced expiratory volume in 1 sec (FEVi) were measured, while the patient was sitting in bed at an angle of 45°, using a Vitalograph spirometer. The best results from three tests were taken and corrected to BTPS. The ratio FEV,:FVC was calculated. Oxygen tension was measured using a Po a sensitive electrode, carbon dioxide using a Stowe-Severinghaus Pco3 electrode (E.I.L. 48c or I.L. 213 blood gas analysers). The results were corrected for temperature difference between the patient and the electrode using the nomograms of Kelman and Nunn (1966). EXTRADURAL ANALGESIA
Operative management. All the patients were premedicated with nitrazepam 10 mg and droperidol 10-20 mg given orally 2 hours before surgery. Anaesthesia was induced with thiopentone followed by alcuronium injected i.v. After insertion of a Magill cuffed orotracheal tube, anaesthesia was maintained with 50% nitrous oxide in oxygen, supplemented with halothane and D. P. G. GRIFFITHS, F.F.A.R.C.S.; A. W. DIAMOND, F.F.AJLC.S.; J. D. CAMERON, B.SC., M.SC.; Frenchay
Hospital, Bristol, BS16 1LE. All correspondence to A.WJD.
Downloaded from http://bja.oxfordjournals.org/ at University of California, Santa Cruz on March 11, 2015
The feasibility of providing postoperative analgesia using thoracic extradural blockade following thoracotomy has been assessed. Extradural block was produced by intermittent injections of 0.5% bupivacaine with adrenaline 1:200,000 or a continuous infusion of 0.25% or 0.125% bupivacaine. The only toxic symptom was drowsiness which was most frequent after a continuous infusion of 0.25% bupivacaine and with arterial plasma bupivacaine concentrations above 1.5 //g/ml. Arterial hypotension was a troublesome complication with all techniques although stability of arterial pressure was more easily achieved with a continuous infusion technique. However, this produced a high incidence of urinary retention. Practical aspects and effectiveness of providing extradural analgesia in patients following thoracotomy are discussed.
49
EXTRADURAL ANALGESIA FOLLOWING THORACIC SURGERY
Management. In the recovery room, the adequacy of the extradural block was assessed by pinprick testing. The extent of the block, the dose of bupivacaine, and the arterial pressure measurements were recorded following each injection of bupivacaine. The first 10 patients were given intermittent injections of 0.5 % bupivacaine with adrenaline 1:200,000 when the segmental block was found to be inadequate, either as a result of pinprick testing or a complaint of pain from the patient. The second 10 patients were given either a continuous infusion of 0.25% bupivacaine from a powered syringe (five patients) or 0.125% bupivacaine (125 ml of bupivacaine 0.5% in 375 ml of 0.9% saline) delivered from a Holter pump (Extra Corporeal Medical Specialties Inc.) (five patients) at a rate to maintain an adequate segmental block. The initial infusion rate was half the recommended mayi'mnm rate of 0.5 mg/kg/hr: that is approximately 5 drops per min of 0.125% bupivacaine solution. Bolus injections of 5-8 ml of 0.25% bupivacaine were given if the block was found to be inadequate. The patients were transferred to the Intensive Care Unit where the block was continued for 48 hours. An anaesthetist remained in the Unit throughout and was available to supervise the management of the block and deal with any complication that might arise. For prophylaxis all patients were given antibiotics for 48 hours before operation and for 5 days after operation. A vigorous regime of physiotherapy was instituted in the postoperative period.
Pain assessment. On the 10th postoperative day, all patients still accessible for interview were asked whether they remembered experiencing any pain in the 48 hours following the operation and, if so, to grade it as absent, slight, moderate or severe. Estimation of bupivacaine concentrations. In eight patients, arterial samples were taken for plasma bupivacaine estimation at 6, 24 and 48 hours following the start of the extradural block. Bupivacaine was extracted from plasma as described by Reynolds and Beckett (1968) except that cyproheptadine was used as the internal standard in place of methadone. Cnromatography was carried out using a Pye Unicam 104 Gas Chromatograph with a flame ionization detector. The column was 0.9 m long, 0.63 cm o.d. glass, packed with 3% OV17 on Gas Chrom Q (100-120 mesh) (Phase Separations Ltd, Queensferry, Flints.). The oven temperature was 220°C and the injection point temperature 270 °C. The carrier gas was nitrogen at a flow rate of 50 ml/min, hydrogen pressure 15 Lb./sq.in. and sensitivity 2-5 X10"10 Af.s.d. The concentration of bupivacaine in the patient's plasma was found by the calculation of peak height ratios of bupivacaine to cyproheptadine and relating these to a calibration curve. RESULTS
The sex and age of the patients and the type of operation are shown in table I. The skin incisions were made through the second to 8th thoracic dermatomes, the intercostal drain emerging from the 9th or 10th interspace. Postoperative pain relief (table II). At 10 days, 15 patients were available for interview: seven of the "intermittent" group and eight of the "continuous" group. 47% of the patients stated that they had been pain-free, 33% graded their pain as slight, 13% moderate and 7% severe. No patient in the intermittent group graded his pain as moderate or severe. 50% of the patients admitting to pain during the block complained of pain from the intercostal drain site. Table m shows the amount of bupivacaine infused. Those patients who were given a continuous infusion of 0 2 5 % bupivacaine received a mean total dose of 1054.6 mg of bupivacaine, those given 0.125% bupivacaine a mean total dose of 766.4 mg and those given intermittent injections a mean total
Downloaded from http://bja.oxfordjournals.org/ at University of California, Santa Cruz on March 11, 2015
incremental doses of fentanyl. Arterial pressure was measured continuously throughout the operation using a radial artery cannula connected to a Tycos manometer (Zorab, 1969). Before operation and under general anaesthesia, the patients were placed in the lateral position with the diseased side dependent. An extradural cannula was inserted, via a Tuohy needle, through the midline at a suitable space between the second and sixth thoracic spines, and connected to a Swinnex millipore filter by means of a Tuohy-Borst chuck. Following a test dose of 2 ml to eliminate the possibility of a subarachnoid injection 4-6 ml of 0.5% bupivacaine with 1:200,000 adrenaline was injected. When the mean arterial pressure decreased to less than 50 mm Hg, it was restored with a rapid infusion of Hartmann's solution. Atropine 0.6 mg was given when the hypotension was accompanied by bradycardia.
BRITISH JOURNAL OF ANAESTHESIA
50 TABLE I. Sex
Mean age (yr)
M Intermittent extradural 8 (0.5% bupivacaine) Continuous extradural 9 (0.25-0.125% bupivacaine) TABLE II.
Intermittent bupivacaine (0.5% with adrenaline) (10 cases)
Pneumonectomy
±6.6
TABLE IV.
Pain relief.
Respiratory
3
2
4
0
function and results.
Extradural technique Intermittent
Continuous
19.8 0.4
5.7 0.7
163.0 51.0
573.5 156.0
Continuous bupivacaine 0.25% (5 cases)
Mean SD
1054.6 593.0
0.125% (5 cases)
Mean SD
766.4 344.0
dose of 573.5 mg (mean of 9.8 doses of mean volume 5.7 ml). The mean duration of action of each dose in the intermittent group was 163 minutes. The continuous infusion group required a mean of 5.1 bolus doses of bupivacaine to maintain an adequate segmental block. The results of respiratory function tests and blood gas analyses before operation and at 24 and 48 hours and 10 days after operation are shown in table IV. Using the paired f-test for comparison of mean values, all the postoperative values of FEV,, FVC and peak flow were significantly reduced when compared with the preoperative value (P
