Actu unaesth. scand. 1977, 21, 497-503
Effects of Intercostal Nerve Blocks (Etidocaine 0.5%)on Chest Wall Mechanics in Cholecystectomized Patients SVENJAICOBSON and INGRID IVARSSON Departments of Anaesthesiology and Clinical Physiology, University Hospital, Uppsala, Sweden
In 20 patients who had undergone cholecystectomy through a right oblique incision, an intercostal nerve block with etidocaine 0.5% was performed on the day after operation -in 10 patients on the right side only and in the other 10 bilaterally. The block was applied to the 5th-11 th intercostal nerves, inclusive. Tidal volumes, respiratory variations in the perimetry of the chest and abdomen, and intraoesophageal and intragastric pressures were recorded before and after the blockades. From analyses of the relations between the relative contributions of costal and abdominal respiration, on the one hand, and intragastric pressure variations, on the other, it was found that before the blockade the intercostal muscles contributed to respiratory movements at rest, but that this contribution decreased after the blockade - to a greater extent after bilateral than after unilateral blockade. It is assumed that this return to a more normal type of breathing a t rest implies relief for the patients. The nerve block led to no significant change of the fraction of abdominal breathing. Pulmonary elastance decreased after bilateral blockade, but remained unchanged after unilateral. Changes in the functional residual capacity (FRC) were evaluated by transthoracic electrical impedance pneumography. Signs of a reduction were noted after unilateral blockade, but there appeared to be no change after bilateral blockade. Bilateral intercostal block thus seems more satisfactory than unilateral in certain respects. The differences cannot be ascribed such importance, however, that bilateral blocks should be considered obligatory in cholecystectomized patients. Probably the most important effect - the pain relief - is achieved in these patients by a right-sided block only.
Received 10 February, accepted f o r publication 6 March 1977
In a previous investigation, the effect of a (BEECHER1933a and b, STARR& GILMAN bilateral intercostal nerve block on the chest 1942, BRATTSTROM 1954, SIMPSON et al. 1961, wall mechanics was studied in healthy OKINAKA 1966, ALEXANDER et al. 1973, subjects (JAKOBSON & IVARSSON1977b). WAHBAet al. 1975). These changes do not The only changes observed were a slight necessarily imply lung complications, but reduction of the vital capacity (VC) and reflect the way in which pain, abdominal peak expiratory flow rate (PEF) and signs of distension, and muscular spasm and asyna decrease in the functional residual capacity chrony in the abdominal wall and lower part (FRC). A similar investigation on patients of the thorax evoked by the incision affect who had undergone upper abdominal surgery the dynamic and static properties of the chest is now reported. wall ( CAPELLE1935). It is known that, after an upperlaparotomy, The respiratory movements are painful VC is reduced to less than half the preopera- even at rest, and effective alleviation is tive value. Varying reductions of the tidal greatly appreciated. It is widely agreed that volume (VT), of the fraction of abdominal the patients are especially relieved when a breathing (Fab)and of the FRC also occur regional block has been chosen.
498
s. JAKOBSON
AND I . IVARSSON
In the present investigation, measurements were made of variables reflecting chest wall mechanics before and after intercostal nerve block in a group of patients who had undergone cholecystectomy on the previous day. The aim was to determine whether changes occurred during respiration at rest and, if so, whether these might contribute to the feeling of well-being resulting from relief of pain by the blockade technique; and further, to ascertain whether a bilateral nerve block has appreciable advantages over a unilateral block in this respect.
MATERIAL AND METHODS The investigation was performed on 20 patients - 8 women and 12 men - undergoing elective cholecystectomy (Table 1). Apart from the cholecystopathy, all were healthy, as judged by the case history and physical examination. They were all well informed as to the nature and extent of the investigation, and declared their willingness to participate. VC and PEF were measured on the day before the operation, with the patient in the semi-supine position (Table 1).
VC as a percentage of the predicted value (for the sitting posture) was 91.6+_10.0% (mean+_s.d.) for Patients 1-10 (these were subsequently given unilateral nerve blocks) and 89.2+26.0% for Patients 11-20 (bilateral blocks). The corresponding values for PEF were 91.8+9.9% and 95.8 f 8.4%, respectively. No significant differences were found between the groups. The operation was performed under general anaesthesia, with thiornebumal sodium (Pentothal sodium@, Abbott) for induction, pancuroniurn bromide (PavuIon", Organon) for relaxation and Nz0-OZduring IPPV via an endotracheal tube. Fentanyl (Leptanal", Leo) was given for supplementary analgesia. A right oblique incision was made beneath the costal arch. In Patients 8, 16 and 17, a choledochotorny was necessary. For postoperative drainage of the operation field two tubes were inserted through the abdominal wall by a separate incision below the large incision. All patients tolerated the operation well. No special arrangements were made postoperatively. T h e patients were managed according to the ordinary routine procedure observed in this clinic for cholecystectomized patients. After a few hours' observation in the recovery area, they were returned to the ward, where a physiotherapist helped them with breathing exercises which they had practised preoperatively. Subcutaneous injections of ketobemidon chloride (Ketogin", Lundbeck) were given for relief of pain as required.
Preoperative
Subject 1
2 3 4 5 6 7 8 9 10 11
12 13 14 15 16 17 18 19
20
Sex
F M F M M F F F F
M M F F M M M M
M M M
Age yr
Height cm
24 32 49 49 24 49 39 26 31 54 29 25 32 52 55 38 39 30 54 21
165 190 165 172 171 164 164 172 168 175 175 171 169 172 177 169 181 180 184 173
Weight kg
VC 1
PEF I/min
Total dose etidocaine mg
Segments of incornplcte analgesia left
1
right
INTERCOSTAL NERVE BLOCK
499
Table 2 Variables measured or derived in the present investigation. ~~~
VC
Vital capacity, litres, ATPS
PEF
Peak expiratory flow rate, litres/min, ATPS
k’ T
Tidal volume, litres, ATPS
P.,End and P.,End
Intraoesophageal and intragastric pressures, respectively, in cmH,O and relative to atmospheric pressure at the end-tidal position
AP,, and APah
Changes in the pressures between the points a t the start and end of an inspiration for Po, and P,,, respectively
F,,TAP
Tidal volume fraction due to abdominal breathing (Fa,); i.e., the fraction referable to diaphragmatic descent. Estimated by thoraco-abdominal perimetry (TAP)
F, estimated by transthoracic impedance pneumography (TTI) Tidal volume portions due to abdominal and costal breathing, respectively. Costal breathing = the volume portion referable to rib cage expansion. Displaced by the activity of the intercostal muscles and/or the diaphragm. Estimated by TAP AP,,/VT, pulmonary elastance AP,,/Vab, abdominal elastance APab/V,=,rib cage elastance
The investigation was started about 20 h after the operation and 3 h after the last dose of analgesic. The intercostal nerve block was performed with the patient in the lateral position. Injections were given into the 5th to 11 th intercostal spaces, inclusively Patients 1 to 10 on the right side and Patients 11 to 20 on both sides, about 10 cm dorsally to the mid-axillary lines. The injections into the 5th and 6th spaces were given medially to the scapula. The anesthetic agent used was etidocaine 0.5% (Duranestm, ASTRA Lakemedel AB). The total doses are given in Table 1. In the unilateral group, the dose in mg/kg body weight was 2.3k0.4 (meanksd.), and in the bilateral group 3.0k0.4. In order to reduce the duration of discomfort to the patients, it was found necessary to make the injection procedure relatively short. As a result, some of the patients in the bilateral group had a sensation of light-headedness as soon as the injections were completed ; this gradually disappeared during the following half-hour. This sensation was especially pronounced in Patient 13, who was one of the first to have a bilateral block. As the intensity of this side effect may be considered to be related not only to the time factor but also to the dose per kg body weight, it was decided that bilateral blocks should thereafter be reserved for the heavier patients. As a consequence, the sex distribution in the groups became different. Thus the unilateral group included six women, and the bilateral group only two. The mean body weight in the unilateral group was 68.6+ 11.4 kg (ks.d.) and in the bilateral group 79.8k 13.9 kg. The body heights were 170.6k7.9 cm and 175.1 k5.2 cm, respectively. However, neither of these latter differ-
ences between the groups was statistically significant ( P > 0.05). The age distribution in the groups was almost the same: 37.7k 11.7 and 37.5+ 12.4 years in the unilateral and bilateral groups, respectively. No other side effects were observed and pneumothorax did not occur in any of the patients. The latter was checked by chest X-ray after completion of the investigation. The analgesia was tested by the pin-prick method. Certain segments were found to be incompletely anaesthetized (see Table 1). The measured or derived variables are presented in Table 2. The same equipment and mode of procedure were used as in the investigation of healthy subjects mentioned above (JAKOBSON & IVARSSON 1977b). For details, the reader is referred to that paper, and for further information concerning the methods of thoraco-abdominal perimetry (TAP) and transthoracic impedance pneumography (TTI), reference may be made to two articles on these subjects (JAKOBSON & IVARSSON 1977a,JAKOBSON et a]. 1977). The electrodes for TTI were placed a t the level of the 5th rib in the medioaxillary lines. I n Patients 5,6, 12 and 18, they should probably have been placed a little higher, as the signals were too weak to be utilized after the blockade. Thus, measures of changes in FRC were obtained from eight patients in each group. I n each of the patients, the mean value for each variable obtained from seven breaths was recorded. The mean values and standard errors of the mean (s.e. mean) were then calculated for the respective groups from the values before and after the blockades and for the paired differences.
500
s. JAKOBSON
AND I. IVARSSON
The differences were tested statistically by means of Wilcoxon's rank sum test. When the probability (a) that no difference existed exceeded 0.05, the difference was regarded as statistically non-significant. When a was less than 0.05 it was regarded as statistically significant, and this is indicated in the tables by one asterisk. When a was less than 0.01 this is indicated in the tables by two asterisks. Investigation programme The recordings were made with the patient in the semi-supine position, with the upper half of the body elevated 30" from the horizontal plane. The tidal volume and respiratory frequency were optional. The dressing was removed, leaving the wound covered only by surgical tape. Simultaneous TAP, TTI and pneumotachographic recordings. The balloon catheter was passed into the stomach transnasally and the intragastric pressure variations were recorded at the same time as the TAP and pneumotachography. The catheter was then withdrawn until the balloon lay in the lower part of the oesophagus and further recordings were made. The intercostal nerve block was performed. The transducers for TAP, the electrodes for TTI and the balloon catheter were left undisturbed. When the block had been completed, 30 min were allowed to elapse before continuation of the programme. Pin-prick test. 5. The same procedure as in point 2, but this time the intraoesophageal pressure recordings were made first. When the recordings were completed, the balloon catheter was removed. 6. The same procedure as in point 1.
7. Calibration manoeuvre for TAP and T T I (the manoeuvre of variably combined abdominal breathing).
Before the blockades, no statistically significant differences were found between the groups, with one exception, namely that the rib cage elastance (E:,) was significantly lower in the bilateral group (cc
Effects of Intercostal Nerve Blocks (Etidocaine 0.5%)on Chest Wall Mechanics in Cholecystectomized Patients SVENJAICOBSON and INGRID IVARSSON Departments of Anaesthesiology and Clinical Physiology, University Hospital, Uppsala, Sweden
In 20 patients who had undergone cholecystectomy through a right oblique incision, an intercostal nerve block with etidocaine 0.5% was performed on the day after operation -in 10 patients on the right side only and in the other 10 bilaterally. The block was applied to the 5th-11 th intercostal nerves, inclusive. Tidal volumes, respiratory variations in the perimetry of the chest and abdomen, and intraoesophageal and intragastric pressures were recorded before and after the blockades. From analyses of the relations between the relative contributions of costal and abdominal respiration, on the one hand, and intragastric pressure variations, on the other, it was found that before the blockade the intercostal muscles contributed to respiratory movements at rest, but that this contribution decreased after the blockade - to a greater extent after bilateral than after unilateral blockade. It is assumed that this return to a more normal type of breathing a t rest implies relief for the patients. The nerve block led to no significant change of the fraction of abdominal breathing. Pulmonary elastance decreased after bilateral blockade, but remained unchanged after unilateral. Changes in the functional residual capacity (FRC) were evaluated by transthoracic electrical impedance pneumography. Signs of a reduction were noted after unilateral blockade, but there appeared to be no change after bilateral blockade. Bilateral intercostal block thus seems more satisfactory than unilateral in certain respects. The differences cannot be ascribed such importance, however, that bilateral blocks should be considered obligatory in cholecystectomized patients. Probably the most important effect - the pain relief - is achieved in these patients by a right-sided block only.
Received 10 February, accepted f o r publication 6 March 1977
In a previous investigation, the effect of a (BEECHER1933a and b, STARR& GILMAN bilateral intercostal nerve block on the chest 1942, BRATTSTROM 1954, SIMPSON et al. 1961, wall mechanics was studied in healthy OKINAKA 1966, ALEXANDER et al. 1973, subjects (JAKOBSON & IVARSSON1977b). WAHBAet al. 1975). These changes do not The only changes observed were a slight necessarily imply lung complications, but reduction of the vital capacity (VC) and reflect the way in which pain, abdominal peak expiratory flow rate (PEF) and signs of distension, and muscular spasm and asyna decrease in the functional residual capacity chrony in the abdominal wall and lower part (FRC). A similar investigation on patients of the thorax evoked by the incision affect who had undergone upper abdominal surgery the dynamic and static properties of the chest is now reported. wall ( CAPELLE1935). It is known that, after an upperlaparotomy, The respiratory movements are painful VC is reduced to less than half the preopera- even at rest, and effective alleviation is tive value. Varying reductions of the tidal greatly appreciated. It is widely agreed that volume (VT), of the fraction of abdominal the patients are especially relieved when a breathing (Fab)and of the FRC also occur regional block has been chosen.
498
s. JAKOBSON
AND I . IVARSSON
In the present investigation, measurements were made of variables reflecting chest wall mechanics before and after intercostal nerve block in a group of patients who had undergone cholecystectomy on the previous day. The aim was to determine whether changes occurred during respiration at rest and, if so, whether these might contribute to the feeling of well-being resulting from relief of pain by the blockade technique; and further, to ascertain whether a bilateral nerve block has appreciable advantages over a unilateral block in this respect.
MATERIAL AND METHODS The investigation was performed on 20 patients - 8 women and 12 men - undergoing elective cholecystectomy (Table 1). Apart from the cholecystopathy, all were healthy, as judged by the case history and physical examination. They were all well informed as to the nature and extent of the investigation, and declared their willingness to participate. VC and PEF were measured on the day before the operation, with the patient in the semi-supine position (Table 1).
VC as a percentage of the predicted value (for the sitting posture) was 91.6+_10.0% (mean+_s.d.) for Patients 1-10 (these were subsequently given unilateral nerve blocks) and 89.2+26.0% for Patients 11-20 (bilateral blocks). The corresponding values for PEF were 91.8+9.9% and 95.8 f 8.4%, respectively. No significant differences were found between the groups. The operation was performed under general anaesthesia, with thiornebumal sodium (Pentothal sodium@, Abbott) for induction, pancuroniurn bromide (PavuIon", Organon) for relaxation and Nz0-OZduring IPPV via an endotracheal tube. Fentanyl (Leptanal", Leo) was given for supplementary analgesia. A right oblique incision was made beneath the costal arch. In Patients 8, 16 and 17, a choledochotorny was necessary. For postoperative drainage of the operation field two tubes were inserted through the abdominal wall by a separate incision below the large incision. All patients tolerated the operation well. No special arrangements were made postoperatively. T h e patients were managed according to the ordinary routine procedure observed in this clinic for cholecystectomized patients. After a few hours' observation in the recovery area, they were returned to the ward, where a physiotherapist helped them with breathing exercises which they had practised preoperatively. Subcutaneous injections of ketobemidon chloride (Ketogin", Lundbeck) were given for relief of pain as required.
Preoperative
Subject 1
2 3 4 5 6 7 8 9 10 11
12 13 14 15 16 17 18 19
20
Sex
F M F M M F F F F
M M F F M M M M
M M M
Age yr
Height cm
24 32 49 49 24 49 39 26 31 54 29 25 32 52 55 38 39 30 54 21
165 190 165 172 171 164 164 172 168 175 175 171 169 172 177 169 181 180 184 173
Weight kg
VC 1
PEF I/min
Total dose etidocaine mg
Segments of incornplcte analgesia left
1
right
INTERCOSTAL NERVE BLOCK
499
Table 2 Variables measured or derived in the present investigation. ~~~
VC
Vital capacity, litres, ATPS
PEF
Peak expiratory flow rate, litres/min, ATPS
k’ T
Tidal volume, litres, ATPS
P.,End and P.,End
Intraoesophageal and intragastric pressures, respectively, in cmH,O and relative to atmospheric pressure at the end-tidal position
AP,, and APah
Changes in the pressures between the points a t the start and end of an inspiration for Po, and P,,, respectively
F,,TAP
Tidal volume fraction due to abdominal breathing (Fa,); i.e., the fraction referable to diaphragmatic descent. Estimated by thoraco-abdominal perimetry (TAP)
F, estimated by transthoracic impedance pneumography (TTI) Tidal volume portions due to abdominal and costal breathing, respectively. Costal breathing = the volume portion referable to rib cage expansion. Displaced by the activity of the intercostal muscles and/or the diaphragm. Estimated by TAP AP,,/VT, pulmonary elastance AP,,/Vab, abdominal elastance APab/V,=,rib cage elastance
The investigation was started about 20 h after the operation and 3 h after the last dose of analgesic. The intercostal nerve block was performed with the patient in the lateral position. Injections were given into the 5th to 11 th intercostal spaces, inclusively Patients 1 to 10 on the right side and Patients 11 to 20 on both sides, about 10 cm dorsally to the mid-axillary lines. The injections into the 5th and 6th spaces were given medially to the scapula. The anesthetic agent used was etidocaine 0.5% (Duranestm, ASTRA Lakemedel AB). The total doses are given in Table 1. In the unilateral group, the dose in mg/kg body weight was 2.3k0.4 (meanksd.), and in the bilateral group 3.0k0.4. In order to reduce the duration of discomfort to the patients, it was found necessary to make the injection procedure relatively short. As a result, some of the patients in the bilateral group had a sensation of light-headedness as soon as the injections were completed ; this gradually disappeared during the following half-hour. This sensation was especially pronounced in Patient 13, who was one of the first to have a bilateral block. As the intensity of this side effect may be considered to be related not only to the time factor but also to the dose per kg body weight, it was decided that bilateral blocks should thereafter be reserved for the heavier patients. As a consequence, the sex distribution in the groups became different. Thus the unilateral group included six women, and the bilateral group only two. The mean body weight in the unilateral group was 68.6+ 11.4 kg (ks.d.) and in the bilateral group 79.8k 13.9 kg. The body heights were 170.6k7.9 cm and 175.1 k5.2 cm, respectively. However, neither of these latter differ-
ences between the groups was statistically significant ( P > 0.05). The age distribution in the groups was almost the same: 37.7k 11.7 and 37.5+ 12.4 years in the unilateral and bilateral groups, respectively. No other side effects were observed and pneumothorax did not occur in any of the patients. The latter was checked by chest X-ray after completion of the investigation. The analgesia was tested by the pin-prick method. Certain segments were found to be incompletely anaesthetized (see Table 1). The measured or derived variables are presented in Table 2. The same equipment and mode of procedure were used as in the investigation of healthy subjects mentioned above (JAKOBSON & IVARSSON 1977b). For details, the reader is referred to that paper, and for further information concerning the methods of thoraco-abdominal perimetry (TAP) and transthoracic impedance pneumography (TTI), reference may be made to two articles on these subjects (JAKOBSON & IVARSSON 1977a,JAKOBSON et a]. 1977). The electrodes for TTI were placed a t the level of the 5th rib in the medioaxillary lines. I n Patients 5,6, 12 and 18, they should probably have been placed a little higher, as the signals were too weak to be utilized after the blockade. Thus, measures of changes in FRC were obtained from eight patients in each group. I n each of the patients, the mean value for each variable obtained from seven breaths was recorded. The mean values and standard errors of the mean (s.e. mean) were then calculated for the respective groups from the values before and after the blockades and for the paired differences.
500
s. JAKOBSON
AND I. IVARSSON
The differences were tested statistically by means of Wilcoxon's rank sum test. When the probability (a) that no difference existed exceeded 0.05, the difference was regarded as statistically non-significant. When a was less than 0.05 it was regarded as statistically significant, and this is indicated in the tables by one asterisk. When a was less than 0.01 this is indicated in the tables by two asterisks. Investigation programme The recordings were made with the patient in the semi-supine position, with the upper half of the body elevated 30" from the horizontal plane. The tidal volume and respiratory frequency were optional. The dressing was removed, leaving the wound covered only by surgical tape. Simultaneous TAP, TTI and pneumotachographic recordings. The balloon catheter was passed into the stomach transnasally and the intragastric pressure variations were recorded at the same time as the TAP and pneumotachography. The catheter was then withdrawn until the balloon lay in the lower part of the oesophagus and further recordings were made. The intercostal nerve block was performed. The transducers for TAP, the electrodes for TTI and the balloon catheter were left undisturbed. When the block had been completed, 30 min were allowed to elapse before continuation of the programme. Pin-prick test. 5. The same procedure as in point 2, but this time the intraoesophageal pressure recordings were made first. When the recordings were completed, the balloon catheter was removed. 6. The same procedure as in point 1.
7. Calibration manoeuvre for TAP and T T I (the manoeuvre of variably combined abdominal breathing).
Before the blockades, no statistically significant differences were found between the groups, with one exception, namely that the rib cage elastance (E:,) was significantly lower in the bilateral group (cc
