Effects of Intercostal Nerve Blocks (Bupivacaine 0.25% and Etidocaine 0.5%) on Chest Wall Mechanics in Healthy Men

Bilateral blockade of the 5th to 11th intercostal nerves, inclusive, was produced in 14 healthy subjects. In seven, bupivacaine 0.25% was used, and in the other seven, etidocaine 0.5%. The latter has been found to have a stronger motor-blocking action than the former. Before and after the blockade, the vital capacity (VC), peak expiratory flow rate (PEF), tidal volumes, respiratory variations in rib cage and abdominal circumferences and in oesophageal and intragastric pressures were recorded. By transthoracic electrical impedance pneumography, measures indicating changes in the functional residual capacity (FRC) were obtained. Although it was considered that changes in the parameters investigated mainly demonstrated changes in motor function, no differences were found between the drugs. With this form of blockade they seem to have equivalent effects in this respect. Thus, VC decreased by an average of 7% and PEF by 6%. Signs of a reduction of FRC after the blockade were also observed. The blockade had no effect on the partitioning of costal and abdominal breathing at rest. Analysis of the relations between the fractions of costal and abdominal breathing and the corresponding variations in intragastric pressure gave support to the view that in normal individuals both intercostal and abdominal muscles remain passive during respiration at rest. This is thus achieved by the diaphragm alone.     

Effect of intercostal nerve blockade on respiratory mechanics and CO2 chemosensitivity at rest and exercise

Lower intercostal and abdominal muscles interact with other respiratory muscles to produce inspiration as well as expiration. Intercostal nerve blockade from T6-T12 was produced in seven healthy males to study its effect on: 1) supine pulmonary function, 2) inspiratory effort, 3) hypercapnic ventilatory response, including mouth occlusion pressures with and without an expiratory load, and 4) ventilation during progressive exercise on a cycle ergometer. Studies during control and blocked states were performed on different days. Lower chest and abdominal wall paralysis was documented with electromyography. Findings include a minimal decrease in peak expiratory flows with intercostal blockade (P = 0.02), but no other changes in supine resting pulmonary function tests, inspiratory effort, or hypercapnic ventilatory response slopes. Minute ventilation, respiratory rate, and VT/TI during exercise were also minimally increased, indicating an increase in the drive to breathe, which was unrelated to a change in metabolic rate. During exercise, total time to exhaustion was decreased following intercostal nerve blockade. Bilateral intercostal nerve blockade produced minimal decreases in peak expiratory flow at rest in supine subjects. During seated exercise, there was a slight increase in respiratory drive, probably due to minor alterations in the mechanics of breathing induced by intercostal blockade. The authors conclude that, in healthy young subjects, intercostal nerve blockade does not exert a clinically significant adverse affect on pulmonary mechanics and that ventilatory function is well-maintained even at extremes of ventilatory demand.     

Air-flow meter assessment of the effect of intercostal nerve blockade on respiratory function in rib fractures

The respiratory effect of intercostal nerve block for pain from fractured ribs was evaluated in a prospective study of ten hospitalized patients. The respiratory function, evaluated with a Glaxo AirFloMeter, showed significant improvement one hour after induction of blockade, but after six hours the effect had subsided.     

The efficacy of intraoperative internal intercostal nerve block during video-assisted thoracic surgery on postoperative pain

Background. Video-assisted thoracic surgery (VATS) is widely used for many thoracic surgical procedures. Postoperative pain is less after VATS than after conventional thoracic surgery, but is still significant. The objective of this study was to assess the efficacy of thoracoscopic, internal intercostal nerve block in alleviating immediate postoperative pain.

Methods. Thirty-two patients underwent VATS bilateral sympathectomy for the treatment of hyperhidrosis. The patients were randomly divided into two groups with similar demographic and preoperative physiologic parameters. Group A (n = 16) was submitted to thoracoscopic, internal intercostal nerve blocks performed at T2, T3, and T4 intercostal levels using 3 cc of 0.5% bupivacain in each intercostal space. The injections were performed bilaterally, immediately after the sympathectomy, through the same port. Group B (n = 16) underwent bilateral thoracic sympathectomy without the block. During the immediate postoperative period, heart rate, blood pressure, respiratory rate, pain score, and analgesic requirements were monitored every 30 minutes.

Results. No morbidity was recorded in association with the thoracoscopic, internal intercostal nerve block. The mean heart rates (77 ± 6 vs 89 ± 12 beats per minute, p < 0.001), respiratory rates (15 ± 2 vs 18 ± 3 respirations per minute, p < 0.01), pain score (1.9 ± 0.6 vs 2.7 ± 0.5, p < 0.01), and postoperative analgesic requirements (20 ± 18 vs 50 ± 21 mg pethidine HCL, p < 0.001) were significantly lower in group A. There was no significant difference in blood pressures.

Conclusions. Thoracoscopic, internal intercostal nerve block with bupivacain 0.5% during VATS is safe and effectively reduced the immediate postoperative pain and analgesic requirements.     

An anatomical evaluation of the serratus anterior plane block

The serratus anterior plane block has been described for analgesia of the hemithorax. This study was conducted to determine the spread of injectate and investigate the anatomical basis of the block. Ultrasound‐guided serratus anterior plane block was performed on six soft‐fix embalmed cadavers. All cadavers received bilateral injections, on one side performed with 20 ml latex and on the other with 20 ml methylene blue. Subsequent dissection explored the extent of spread and nerve involvement. Photographs were taken throughout dissection. The intercostal nerves were involved on three occasions with dye, but not with latex. The lateral cutaneous branches of the intercostal nerve contained dye and latex on all occasions. The serratus plane block appears to be mediated through blockade of the lateral cutaneous branches of the intercostal nerves. Anatomically, serratus plane block does not appear to be equivalent to paravertebral block for rib fracture analgesia.     

Respiratory Performance after Upper Abdominal Surgery. A Comparison of Pain Relief with Intercostal Blocks and Centrally Acting Analgesics

The respiratory capacity was studied during the first 2 days postoperatively in 94 patients, aged 19 to 75 years and undergoing surgery through an upper abdominal incision. Postoperative pain relief was randomly administered, either by intercostal block (i.c.b.) and centrally acting analgesics on demand, or by centrally acting analgesics alone. Respiratory studies comprising forced vital capacity (FVC), forced expiratory volume in one second (FEV1), peak expiratory flow rate (PEF) and analysis of arterial blood gases were made. Bilateral i.c.b. given after surgery performed through a midline incision did not improve the respiratory function, whereas unilateral i.c.b. after surgery through a subcostal incision had positive effects. Thus postoperative i.c.b. following cholecystectomy performed through a subcostal incision resulted in higher FVC, FEV1 and PEF values than without i.c.b. at least during the time of effective nerve block. I.c.b. after subcostal incision also improved arterial oxygen tension. The patients undergoing cholecystectomy and receiving a second i.c.b. 8 h after the first one had better respiratory function than the patients without any block during the first 2 days postoperatively.     

Intercostal nerve blockade for children

A modified technique of intercostal nerve blockade is described which is suitable for use in children. Ten patients received intercostal nerve blockade on a total of 29 occasions in order to provide analgesia following liver transplantation and to facilitate weaning from artificial ventilation of the lungs. The opioid requirement of patients who received intercostal nerve blockade was considerably lower than that of those who did not; 56% of the children who received intercostal nerve blockade required no additional analgesia. One child, the first to receive intercostal nerve blockade, developed a pneumothorax following the procedure. The technique has proved to be safe in skilled hands. It is an acceptable method of postoperative analgesia in children after liver transplantation and may be a useful technique in the management of other paediatric patients.     

The dose response and effects of dexamethasone on bupivacaine microcapsules for intercostal blockade (T9 to T11) in healthy volunteers

Biodegradable microcapsules containing bupivacaine/dexamethasone produce an anesthetic duration of 7-11 days in animal models. In this investigation, we explored the effect of increasing doses (Part 1) and the effect of including dexamethasone (Part 2) on the onset, density, and duration of analgesia and anesthesia produced by bupivacaine microcapsules. Concentrations ranging from 0.3125% to 5.0% in microcapsules were compared with 0.25% aqueous bupivacaine (bilateral injection, three intercostal nerves, 2 mL per nerve) (Part 1). Part 2 compared 2.5% microcapsules with or without the inclusion of dexamethasone by unilateral blockade. Sensory block was assessed by pinprick, temperature sensation, and subjective numbness (0, not numb; 10, totally numb). Pharmacodynamic assessments and plasma drug concentrations of bupivacaine and dexamethasone were measured for 96 h. The onset time was reduced and the duration of analgesia increased over the 0.3125%-5.0% dose range (P < 0.02). Onset with 2.5% microcapsules approximated that of 0.25% aqueous bupivacaine. Microcapsule block duration increased to at least 96 h and was significantly longer than aqueous bupivacaine (P < 0.001). Inclusion of dexamethasone increased the duration of pinprick anesthesia in 2.5% microcapsules (P = 0.03). We conclude that bupivacaine/dexamethasone microcapsules are well tolerated and demonstrate a dose-related effect in onset and duration of intercostal blockade. Inclusion of dexamethasone increases intercostal block anesthesia.     

Incidence of pneumothorax from intercostal nerve block for analgesia in rib fractures

BACKGROUND: The incidence of pneumothorax (PTX) after individual intercostal nerve block (INB) for postoperative pain reportedly varies from 0.073% to 19%.1-3 This study investigated the incidence of PTX after INB for rib fractures. METHODS: We conducted a retrospective chart review of patients admitted between January 1996 and December 1999 with rib fractures who received INB. RESULTS: One hundred sixty-one patients received 249 intercostal nerve block procedures (INBPs). An INBP is one session where a set of intercostal nerves are blocked. A total of 1,020 individual intercostal nerves were blocked. There were 14 pneumothoraces. The overall incidence of PTX per patient was 8.7%, with an incidence of PTX per INBP of 5.6%. The incidence of PTX was 1.4% for each individual intercostal nerve blocked. CONCLUSION: The incidence of PTX per individual intercostal nerve blocked is low. INB is an effective form of analgesia, and for most patients with rib fractures one INBP is sufficient to allow adequate respiratory exercises and discharge from the hospital.     

Cardiovascular effects of two different regional anaesthetic techniques for unilateral leg surgery

Background : Cardiovascular function was assessed in 20 ASA I-II patients, scheduled for elective orthopaedic surgery with tourniquet in order to compare the haemodynamic changes induced by unilateral spinal anaesthesia and combined sciaticofemoral nerve block.
Methods : After baseline measurement of cardiovascular parameters, patients were randomized to receive unilateral spinal anaesthesia or combined sciatico-femoral nerve block. Spinal anaesthesia was obtained by 8 mg of hyperbaric bupivacaine 0.5% slowly injected (speed=0.02 ml s-¹) through a 25-G Whitacre spinal needle with the bevel orientated towards the dependent side and patients lying on their operated side for 15 min (group S, n=10). Combined sciatico-femoral nerve block was obtained by 7 mg kg-¹ of mepivacaine 2% (group NB, n = 10). Haemodynamic variables were recorded 5, 10, 15, and 30 min after anaesthetic injection before surgery was started.
Results : Anthropometric data, duration of surgery and acceptability of anaesthetic techniques were similar in the 2 groups. In 8 patients of group S, spinal block was restricted to the operated side (pinprick test and Bromage scale), while the other 2 patients developed bilateral spinal block after being turned supine. NB patients showed no haemodynamic changes during the study, whereas patients in group S showed a small but significant decrease of mean arterial blood pressure (P<0.002 vs baseline and P<0.04 vs NB), cardiac index (P<0.01 vs baseline and P0.01 vs NB), and stroke volume index (P<0.01 vs baseline and P<0.01 vs NB).
Conclusion : Both sciatico-femoral and unilateral spinal blockade provide adequate anaesthesia for unilateral leg surgery with tourniquet. The former technique affects cardiovascular performance less than the latter one.     

Short-term changes in pulmonary function and respiratory movements after cardiac surgery via median sternotomy

OBJECTIVE--To study the changes in bilateral respiratory motion and pulmonary function following sternotomy and the relationships between the changes in respiratory movements, spirometry, radiographic analyses, and several intra-operative surgical characteristics. DESIGN--Respiratory motion during deep breathing and lung volumes were measured in 20 patients (mean age 65 years, SD 16) before and after median sternotomy. Chest x-rays were analyzed pre- and postoperatively and a variety of perioperative variables were measured. RESULTS--Average abdominal motion decreased to 57% of preoperative values bilaterally 1 week postoperatively, the average lower thoracic motion decreased to 72%, and the average upper thoracic motion decreased to 87%, whereas the right upper thoracic motion increased 3% compared with preoperative values. Lung volumes decreased to around 60% of preoperative values (p<0.05). Significant correlations were found between the decrease in pulmonary function and the mean respiratory movements. Abnormal chest radiographs were found in all patients. CONCLUSION--The breathing pattern before sternotomy is predominantly abdominal but moves to a thoracic and upper thoracic pattern postoperatively and is associated with reduced pulmonary function. Therapeutic interventions aimed at correcting the less effective upper thoracic breathing pattern should likely be implemented.     

The alkalinisation of bupivacaine for intercostal nerve blockade

A double-blind randomised study was performed to investigate the effect of pH adjustment of bupivacaine, with adrenaline 1:200,000, on the duration of block and pain relief after intercostal nerve blockade following thoracotomy. One group (n = 10) received bupivacaine with adrenaline 1:200,000 (pH = 4.1) and the other (n = 10) received alkalinised bupivacaine with adrenaline 1:200,000 (pH = 6.9). There was no significant difference in block duration (mean 23.9 and 26.4 hours respectively) visual analogue pain scores or morphine usage. Patients were more likely to have a block during the first 12 hours if they received alkalinised bupivacaine (p less than 0.01, Chi-squared test). A progressive regression of block, not previously described, was observed, explicable by means of spread of local anaesthesia to adjacent intercostal nerves. Alkalinisation of bupivacaine with adrenaline for intercostal nerve blockade has little clinical benefit.     

Lumbar Plexus Block Using High-pressure Injection Leads to Contralateral and Epidural Spread

Background: The main advantage of lumbar plexus block over neuraxial anesthesia is unilateral blockade; however, the relatively common occurrence of bilateral spread (up to 27%) makes this advantage unpredictable. The authors hypothesized that high injection pressures during lumbar plexus block carry a higher risk of bilateral or neuraxial anesthesia.

Methods: Eighty patients undergoing knee arthroscopy (age 18-65 yr; American Society of Anesthesiologists physical status I or II) during a standard, nerve stimulator-guided lumbar plexus block using 35 ml mepivacaine, 1.5%, were scheduled to be studied. Patients were randomly assigned to receive either a low-pressure (< 15 psi) or a high-pressure (> 20 psi) injection, as assessed by an inline injection pressure monitor (BSmart(R); Concert Medical LLC, Norwell, MA). The block success rate and the presence of bilateral sensory and/or motor blockade were assessed.

Results: An interim analysis was performed at n = 20 after an unexpectedly high number of patients had neuraxial spread, necessitating early termination of the study. Five of 10 patients (50%) in the high-pressure group had a neuraxial block with a dermatomal sensory level T10 or higher. In contrast, no patient in the low-pressure group (n = 10) had evidence of neuraxial spread. Moreover, 6 patients (60%) in the high-pressure group demonstrated bilateral sensory blockade in the femoral distribution, whereas no patient in the low-pressure group had evidence of a bilateral femoral block.     

EFFECT OF HIGH THORACIC EXTRADURAL ANAESTHESIA ON VENTILATORY RESPONSE TO HYPERCAPNIA IN NORMAL VOLUNTEERS

We have investigated, in six healthy male volunteers, the effectof high thoracic extradural anaesthesia on the ventilatory patternand hypercapnic ventilatory response. Ventilatory variableswere determined using a respiratory inductive plethysmograph.Duration of inspiration, rib cage excursion and its contributionto tidal volume decreased significantly following extraduralanaesthesia, while mean inspiratory flow rate and minute ventilationincreased. End-tidal PCO₂ and the tidal excursion of the abdomenwere unchanged. Hypercapnic ventilatory response decreased significantlyfollowing extradural anaesthesia, principally because of therib cage component. The slope of the abdominal component didnot change significantly. The results indicate that mechanicalimpairment of rib cage movement can produce decreased ventilatoryresponse to carbon dioxide. The ventilatory impairment and thechanges in breathing pattern induced by the high thoracic extraduralanaesthesia probably reflect blockade of the efferent or afferentpathway (or both) of the intercostal nerve roots.     

A case report of long-term post-thoracotomy pain management with intrapleural bupivacaine

A 50-year old woman with right post-thoracotomy pain was referred to us for assistance with pain control. She required pentazocine 60-150 mg per day before our treatment. First, we treated her with intercostal nerve block or oral morphine sulfate. But the result was not satisfactory after five months. Then we tried intrapleural bupivacaine. An epidural catheter was inserted into the pleural space from eight intercostal space at the anterior axillary line and 10 ml of 0.5% bupivacaine was instilled. The treatment was effective for about 4-5 hours. We continued this method for 42 days with 10 ml of 0.25% or 0.5% bupivacaine once or twice a day. She felt so good from the intrapleural analgesia and could be discharged. There was no hypotension, respiratory depression, urinary retention except burning thoracic sensation. We think it is possible to use this intrapleural bupivacaine to treat a certain kind of unilateral chronic pain.     

Single-shot Intercostal Nerve Block as an Adjunct to Post-operative Pain Control for Upper Abdominal Surgery in the Obese Patient

One hundred and ninety-two obese patients presented for upper abdominal surgery, of which 110 received general anaesthesia with opioid analgesia and 82 patients received general anaesthesia with opioid analgesia plus a single-shot intercostal nerve block of 0.5% bupivacaine in 1:200,000 adrenaline. A significant increase in the time to first post-operative opioid dose and a significant reduction in the number of doses over the first 12 and 24 h periods were noted in the patients receiving intercostal nerve block.     

Audit of initial use of the ultrasound-guided transversus abdominis plane block in children

The extent of dermatomal block post transversus abdominis plane block is described in adults as T7-L1; other authors argue extent above T10 is infrequent (supra-iliac 20 ml injection). A paediatric guideline recommends this block for upper and lower abdominal surgery using 0.2 ml/kg. We aimed (through prospective audit) to document the multi-level block achieved with ultrasound-guided transversus abdominis plane block in children having abdominal surgery, during a departmental training period. Data included patient, anaesthetic and surgical details, transversus abdominis plane block characteristics (anterior supra-iliac injections) and dermatomal blockade to ice. Twenty-seven children received 38 blocks performed by 58% consultant and 42% trainee operators (90% novices): 16 unilateral/11 bilateral for umbilical (1), inguinal (13), laparoscopic (8) and laparotomy (5) surgery. Dermatomal assessment for 35 blocks (mean local anaesthetic volume 0.4 ml/kg [SD 0.2]) revealed the median blockade achieved was 3 dermatomes (interquartile range 3 to 4) involving T10 to L1 in 75% of patients. Eight blocks (six patients) also involved T8 and T9, following 0.31 to 0.81 ml/kg. One patient (3% of assessed blocks) had no block to ice at 60 minutes, but required no postoperative analgesia. Ultrasound-guided transversus abdominis plane blocks performed by supra-iliac approach and novice operators produced lower abdominal sensory blockade in children of usually 3 to 4 dermatomes, and should be offered for lower abdominal surgery only, as only 25% had upper abdominal block extension. The optimal local anaesthetic dose/volume, duration of effect and utility for these blocks in relation to peripheral and neuraxial blockade needs clarification.     

Severe pneumothorax after intercostal nerve blockade: A case report

Background: Intercostal nerve blockade is recognized as an efficient and safe regional anesthetic technique. Although an appropriate technique was applied, we report a severe pneumothorax associated with this type of regional anesthesia.
Methods: A 57-year-old female patient underwent block of intercostal nerves 3 to 8 for interstitial radiotherapy of the left breast in the sitting position. Calcified residual foci in the right upper lobe from a previous primary infection of tuberculosis were diagnosed by preoperative x-ray. After completion of the blocks in the midline of the axilla, the patient complained of pain between the scapulas, developed severe dyspnea and panic, and felt as if her life was in jeopardy. A severe pneumothorax was diagnosed and a chest tube was placed. After the application of the chest tube, the patient recovered quickly.
Conclusion: Extra caution should be used in applying this procedure to patients with underlying chronic lung disease, especially on the opposite side. Our case demonstrates that in all patients undergoing intercostal nerve blockade preference should be given to the approach at the dorsal angulation of the rib in the lateral or prone position due to its lower risk of pneumothorax.     

Factors Influencing the Respiratory Capacity after Upper Abdominal Surgery

The analgesic requirement and some factors influencing the respiratory capacity after upper abdominal surgery were studied during the first 2 days postoperatively in 417 patients, aged 17 to 84 years, undergoing surgery in the upper part of the abdomen. The operations were cholecystectomy or choledocholithotomy through a subcostal incision, partial gastric resection, repair of a diaphragmatic hernia or vagotomy through a midline incision. Pain relief was achieved in a random order either by intercostal block (i.c.b.) and centrally acting analgesics on demand, or by centrally acting analgesics alone. The analgesic demand was recorded, and the respiratory capacity was monitored by the peak expiratory flow rate (PEF). A smaller analgesic requirement and a smaller change in PEF were found after cholecystectomy than after any other kind of surgery. The demand for analgesics was age-dependent, and patients under 60 years of age demanded more than those aged 60 years and older. Bilateral i.c.b. given after surgery through a midline incision had few advantages, but unilateral i.c.b. following cholecystectomy and choledocholithotomy with a subcostal incision had positive effects. Thus it decreased the demand for centrally acting analgesics and resulted in higher PEF values than without i.c.b. for cholecystectomy during the period of effective nerve block and for choledocholithotomy for 2 whole days postoperatively. Smokers seemed to benefit from i.c.b. for 2 postoperative days. The reduction of PEF after cholecystectomy also seemed to be related to the duration of treatment with centrally acting analgesics.