11th Intercostal Nerves Research Articles

Anatomical Study of Abdominal Wall Muscle Innervation to Optimize Retroperitoneal Vascular Approach

INTRODUCTIONDifferent surgical approaches are used in aortic surgery. Retroperitoneal approaches can result in abdominal wall weakness and flank bulging. These approaches often require dissection of the anterolateral or anteromedial muscles of the abdominal wall. During dissection, the underlying nerves are at great risk of injury, which induces significant complications in abdominal wall muscles. Few studies have been conducted to minimize the risk of injury to these nerves. OBJECTIVESThis study aims to describe the trajectory of abdominal muscle motor nerves and their relationship to ribs and other anatomical landmarks. The secondary objective is to optimize surgical approaches by preserving the nerves. METHODWe conducted 12 dissections on fresh cadavers. Nerve trajectories, communication between the intercostal nerves (9th–10th–11th) and the subcostal nerve (12th), and the distance from the nerve to the estimated projection point of intersection with the abdominal midline, umbilicus, and iliac crest was recorded. RESULTSOur dissections identified the 12th subcostal nerve as the largest nerve. The 11th intercostal nerve exhibits more accessory branches than other nerves. Multiple communications and branches were observed between the 10th and 11th intercostal nerves and between the 11th and 12th nerves in the region from the anterior axillary line to the mid-clavicular line. The estimated projection point of intersection with the midline was 7.92 ± 1.24 cm supraumbilical for the 9th intercostal nerve, 3.92 ± 1.18 cm supraumbilical for the 10th, 1.08 ± 1.52 cm at the umbilical level for the 11th, and -3.33 ± 0.83 cm infraumbilical for the subcostal nerve. The distance between the iliac crest and the iliohypogastric nerve in the lateral jackknife position was 2.54 ± 0.65 cm. The 11th nerve had an angle in relation to the rib of between -45° and -10° (average: -24.6°), and the 12th nerve had a similar angle of between -30° and 0° (average: -18.3°). For the 11th nerve, the distance was between 0 and 5.5 cm (average: 2.92 cm); for the 12th nerve, it was between 0 and 3.0 cm (average: 1.71 cm). CONCLUSIONTo preserve the 11th nerve, the optimal approach is a straight incision starting from the upper edge of the 11th rib towards the midline, 4 cm above the umbilicus; for the 12th nerve, the optimal approach is a straight incision starting from the upper edge of the 12th rib towards the midline, 1 cm below the umbilicus; for the iliohypogastric nerve, the optimal approach is an incision close to the iliac crest at a distance <1.5 cm. The estimated projection point of intersection between the nerve directions towards the midline can indicate the anatomical trajectory of nerves. A nerve projection towards the midline can provide valuable information about the anatomical location of a nerve. This study has utility in optimizing surgical approaches. A clinical study can confirm these anatomical results.

Transient flank bulge after percutaneous nephrolithotomy

Introduction: Percutaneous nephrolithotomy (PCNL) is considered as the “gold standard” treatment for large (&gt;2 cm) and complex kidney stones. We present a case of transient tone loss of the anterolateral abdominal wall, which is a rare complication after PCNL. Case Report: A 50-year-old male with a complete staghorn stone of the right kidney underwent standard PCNL in prone position at the 11th intercostal space. On the 6th post-operative day the patient complained on painless bulge in the right flank. Computed tomography (CT) scan in supine position revealed no signs of herniation, retroperitoneal hematoma, or residual fragments. Flank bulge was attributed to the muscle tone loss either because of the 11th intercostal nerve injury by the needle or nerve compression by the Amplatz sheath. Within next six months flank bulge has completely resolved. Conclusion: Flank bulge after PCNL although rare but possible and transient condition. Nerve injury seems to be the most likely cause.

Bilateral Transversus Abdominis Plane Block versus Epidural analgesia for Postoperative Pain Relief in Lower Abdominal Surgery

Abstract Background epidural and caudal analgesia have been considered the gold-standard techniques after abdominal surgery for adults and children, respectively. The techniques consist of injecting the local anesthetic within the epidural space, between the ligamentumflavum and the dura mater. Depending on the surgical site and the level of injection, cervical, thoracic, or lumbar nerve roots are blocked after their emergence from the neural foramen. Epidural and caudal analgesia have technical drawbacks with epidural local anesthetic associated with hypotension secondary to the sympathetic blockade.In the last decade, a new abdominal truncal block, called the tranversusabdominis plane (TAP) block, was described consisting of local anesthetic injection between the internal oblique and transversusabdominis muscle. This block provides analgesia by blocking the 7th to 11th intercostal nerves (T7–T11), the subcostal nerve (T12), and the ilioinguinal nerve and iliohypogastric nerve (L1–L2). Aim of the Work to compare the analgesic efficacy of epidural analgesia and transverse abdominis plane (TAP) block to provide postoperative analgesia after abdominal surgery. Methods sixty patients undergoingLower Abdominal Surgery were randomly divided into 2 equal groups by Closed Envelope Method. patients scheduled for Lower Abdominal surgery were assessed preoperatively in the form of evaluation of their medical history, their laboratory investigations and for fulfilling the above inclusion criteria.Patients Preparation was done by 2 mg Dormicum IV injection as a sedation preoperatively. After obtaining baseline vital signs, All patients received GA; sevoflurane was used for induction and maintenance of anesthesia, IV cannula was inserted and laryngeal mask airway (LMA) to secure the airway.Patients were divided randomly into two groups, each group consists of 30 patients. Group A: Patients in this group received Epidural analgesia, patients were placed in sitting position, Epidural block was administered under sterile conditions with a 18 G Touhy needle using a standard loss of resistance technique. After negative aspiration, 1ml/kg of 0.25% bupivacaine was injected. Group B: Patients in this group received US guided TAP block on the same side of surgery, patients were placed in supine position, linear US probe (high frequency probe 10–12 MHz) connected to a portable US unit (SonoSite, USA) was placed in the mid-axillary plane midway between the lower costal margin and the highest point of iliac crest. After skin disinfection, a 23-G 50-mm needle with an injection line was inserted in plane with the probe. Once the tip of the needle was placed in the space between the internal oblique abdominal muscle and transverses abdominis muscle, and after negative aspiration, 0.5 ml/kg 0.25% bupivacaine was injected. The following parameterswas assessed and recorded Hemodynamic monitoring, Assessment of postoperative painUsing visual analogue scale score, Any case of failed block was recorded, Doses of analgesics required intraoperatively and during the first 2 hours postoperatively were recorded. In case of failed block, 1 mic/kg Fentanyl IV was given. Complications During and after the procedurewere recorded. Results There was no significant differences regarding Demographic data, Heart Rate, SPO2 and duration of surgerybetween both groups. There were significant difference between both group regarding systolic blood pressure, Diastolic blood pressure, visual analogue score, need of analgesic, mobilization postoperative, pain on coughing and hospital stay Conclusion The current study revealed that Epidural block provided significantly prolonged postoperative analgesia, reduced the postoperative analgesic requirements compared with Ultrasound guided TAP Block in patients undergoing lower abdominal surgery. Both analgesic techniques are safe.

Anatomical feasibility of anastomosing intercostal nerves (D10&D11) and subcostal nerve (D12) to S2 ventral root and lumbar plexus for management of bladder function after spinal cord injury

ObjectiveThe transfer of peripheral nerves originating above the level of injured spinal cord into the nerves/roots below the injury is a promising approach. It facilitates the functional recovery in lower extremity, bladder/bowel and sexual function in paraplegics. We assessed anatomical feasibility of transfer of lower intercostal nerves to S2 ventral root in human cadaver for management of neurogenic bladder dysfunction in patients with spinal cord injury. MethodsStudy was performed in five formalin fixed cadavers. Cadavers were placed in prone position. A transverse incision was made along 11th ribs on both sides and 10th, 11th Intercostal nerves (ICN) and subcostal nerve were harvested up to maximum possible length. In four cadavers the ventral root of S2 was exposed by endoscope and in one by the standard open laminectomy. Intercostal nerves were brought down to lumbo-sacral region, S2 ventral root was cut cranially and feasibility of intercostal to S2 anastomosis was assessed. ResultsThe mean length of intercostal nerves was 18.4 cm for the 10th 19.5 cm for the 11th and 22.15 cm for the subcostal nerve. The length of harvested nerve and the nerve length necessary to perform sacral roots neurotization were possible in all cases by only by subcostal nerve while T11 and T10 ICN fall short of the required length. ConclusionFor Spinal cord lesions located at the conus, subcostal nerve could be connected to ventral root of S2 in an attempt to restore bladder function while 10th and 11th ICN had enough length to neurotize lumbar plexus.

Reconstruction of Temporal Bone Defect Using a Vertically-Oriented Free Muscle-Sparing Rectus Abdominis Musculocutaneous Flap

Reconstruction of a temporal bone defect after tumor ablation should provide watertight filling and adequate resurfacing. A muscle-sparing rectus abdominis musculocutaneous (ms-RAMC) flap with de-epithelized skin paddle has been used and early experience was reported. Case series enrolled 7 patients who underwent free ms-RAMC flap after tumor ablation for external auditory canal cancer. Vertically oriented flap was harvested with central strip of muscle. Distal skin paddle was de-epithelized to fill the bony defect. Immediate facial nerve reconstruction was performed whenever indicated. The average operation time for reconstruction was 280 minutes. No early complication was reported. An ms-RAMC flap with de-epithelized skin paddle can be used for temporal bone defect reconstruction with its anatomic consistency and technical simplicity. It can provide sufficient bulk for water tight packing that lasts after irradiation. The 11th intercostal nerve can be harvested during pedicle dissection. Muscle sparing technique could minimize donor-site morbidity.

The Subcostal Nerve During Lateral Approaches to the Lumbar Spine: An Anatomical Study with Relevance for Injury Avoidance and Postoperative Complications Such as Abdominal Wall Hernia.

Lateral approaches to the spine are increasing in popularity. However, details of the innervation pattern of the abdominal oblique muscles with the initial dissection have not been well studied. Ten adult fresh-frozen cadavers (20 sides) were placed in the lateral position. On each side, the region in which transpsoas approaches are performed, between the iliac crest and the 12th rib, was dissected. The nerves, their course, and their muscular supply were studied. The subcostal nerve is the predominant nerve supply for the anterolateral abdominal muscle innervation. It is larger and has a wider field of distribution and more branches (8 on average) compared with the L1 (4 on average) and 11th intercostal nerves (2 on average 2). The proximal 6-10 cm of each nerve has few if any branches. The subcostal nerve is often (75%) located up to 5 cm inferior to the 12th rib in its initial course. The area of least concentration ("safe zone") is located at an approximate midpoint between the lower edge of the 12th rib and the superior-most aspect of the iliac crest. A previously undescribed branch of the subcostal nerve was found traveling posterior to the quadratus lumborum and joining the remaining subcostal nerve in an anastomosis at or near the lateral position. Knowledge of the innervation and nerve dominance patterns might help decrease postoperative complications such as sensory deficits or abdominal wall hernias. The subcostal nerve is the dominant nerve in both size and innervation of the oblique muscles in the lateral position, transpsoas approach.

Paraplegia following intercostal nerve neurolysis with alcohol and thoracic epidural injection in lung cancer patient.

The goal of cancer treatment is generally pain reduction and function recovery. However, drug therapy does not treat pain adequately in approximately 43% of patients, and the latter may have to undergo a nerve block or neurolysis. In the case reported here, a 42-year-old female patient with lung cancer (adenocarcinoma) developed paraplegia after receiving T8-10 and 11th intercostal nerve neurolysis and T9-10 interlaminar epidural steroid injections. An MRI results revealed extensive swelling of the spinal cord between the T4 spinal cord and conus medullaris, and T5, 7-11, and L1 bone metastasis. Although steroid therapy was administered, the paraplegia did not improve.

Ultra-sound Guided Intercostal Neurolysis for Intractable Pain Arising out of Rib Fracture

Introduction: Rib fracture from blunt chest trauma leads to considerable morbidity, which increases with each rib fracture. There are multiple methods of pain relief from rib fracture, but most of them are effective for short duration and in acute pain setting. In a few patients, whom the pain becomes chronic, the treatment could be difficult. In this case report, we are describing a patient with severe chest pain arising out of 1st to 11th rib fracture, whose pain was not controlled even after multiple interventions and was on multiple medications. Case presentation: We had done ultrasound guided intercostal neurolysis of 1st to 11th intercostal nerve with 2 ml of 50% alcohol, after having more than 80% relief from the ultrasound guided diagnostic intercostal block at all the levels. After the neurolysis, there was good pain relief of chest pain, and the patient was able to take deep breaths and do chest physiotherapy. The pain relief from the neurolysis lasted for more than 6 months .There was no immediate and delayed complications after the procedure. Conclusion: The Ultrasound guided intercostal neurolysis can be a good long lasting alternative for the patients with uncontrolled severe pain from rib fracture.

Wound Complications of the Retroperitoneal Approach for the Abdominal Aortic Aneurysm Repair—An Evaluation of Abdominal Bulge Formation—

To evaluate the incidence of wound complications after the retroperitoneal approach for abdominal aortic aneurysm (AAA) repair, and to ascertain the cause of abdominal bulge (AB). Forty-three patients with AAA repair via the retroperitoneal space were retrospectively investigated. Wound complications and their incidence were studied by chart review. The thickness of the abdominal wall muscle was measured by follow-up computed tomography films. Compound muscle action potentials (CMAPs) of the abdominal rectus muscle were examined for three bulge patients and three non-bulge patients. Wound hypoesthesia (30%), wound numbness (21%), AB (7%), and wound pain (2%) were found in these patients. The thickness of the abdominal wall muscle was reduced in the incision side. CMAP of abdominal rectus muscle in the incision side disappeared only in AB patients. (1) Wound hypoesthesia and numbness displayed a high incidence. (2) Atrophy of the abdominal wall muscle in the incision side was found in these patients. (3) The cause of AB is considered to be muscle atrophy induced by denervation injury of an 11th intercostal nerve. (4) To avoid an eleventh intercostal nerve injury must be deemed the most effective method for preventing AB.

Avoiding Abdominal Flank Bulge after Lumbotomy Incision: Cadaveric Study and Ultrasonographic Investigation

ObjectiveThe object of this study was to better define the relevant anatomy and innervation of the anterolateral abdominal wall musculature seeking to avoid abdominal wall complication after open donor nephrectomy. We dissected four cadavers and retrospectively assessed donor ultrasonographic imaging of anterolateral abdominal muscle atrophy after donor nephrectomy with a lumbotomy incision. MethodsAnatomic study was performed on four cadavers using bilateral dissections. The 8th, 9th, 10th, 11th, and 12th (subcostal) intercostal nerves were dissected from the intercostal space to the rectus sheath. With the experience gained from anatomic study, we performed 40 living donor incisions 1.5 to 2 cm medial to the tip of 12th rib, toward the lateral border of the rectus muscle and the umbilicus. Donors were invited to the hospital at 1 year postoperative to examine abdominal wall complications. Ultrasonography (USG) was performed to assess the thickness of the abdominal wall muscles bilaterally to ascertain whether there was atrophy. ResultsAll distal intercostal nerves ran as multiple mixed segmental nerves, communicating with each other widely within the neurovascular plane. The thick 12th nerve was located at 1.5 to 2 cm medial and under the tip of the 12th rib, running to the suprapubic area. Postoperative USG confirmed that the mean percent thickness of the abdominal muscles of the operative side was not significantly different from the other side (P < .05). ConclusionMost significant intercostal nerve contributions to the anterolateral abdominal wall arise from T12. Damage to the intercostal nerves will be minimal if the lombotomy incision is performed above the safe line between the tip of the 12th rib and the umblicus.

Surgical Anatomy of the 10th and 11th Intercostal, and Subcostal Nerves: Prevention of Damage During Lumbotomy

In a descriptive, inventorial anatomical study we mapped the course of the 10th and 11th intercostal nerves, and the subcostal nerve in the abdominal wall to determine a safe zone for lumbotomy. We dissected 11 embalmed cadavers, of which 10 were analyzed. The 10th and 11th intercostal nerves, and the subcostal nerve were dissected from the intercostal space to the rectus sheath. Analysis was done using computer assisted surgical anatomy mapping. A safe zone and an incision line with a minimum of nerve crossings were determined. The 10th and 11th intercostal nerves were invariably positioned subcostally. The subcostal nerve lay subcostally but caudal to the rib in 4 specimens. The main branches were located between the internal oblique and transverse abdominal muscles. The nerves branched and extensively varied in the abdominal wall. A straight line extended from the superior surface of the 11th and 12th ribs indicated a zone with lower nerve density. In 5 specimens the 10th and 11th intercostal nerves crossed this line from the superior surface of the 11th rib. In 5 specimens neither the 11th intercostal nerve nor the subcostal nerve crossed this extended line from the superior surface of the 12th rib up to 15 cm from the tip of the rib. Damage is inevitable to branches of the 10th or 11th intercostal nerve, or the subcostal nerve during lumbotomy. However, an incision extending from the superior surface of the 11th or 12th rib is less prone to damage these nerves. Closing the abdominal wall in 3 layers with the transverse abdominal muscle separately might prevent damage to neighboring nerves.

The Paraspinal Splitting Approach: A Possible Approach to Perform Multiple Intercosto-Lumbar Neurotizations

Descriptive anatomy. OBJECTIVE.: To describe the anatomy associated with the extensive transmuscular paraspinal approach required to perform multiple intercosto-lumbar neurotizations. Neurotization of lumbar roots using lower intercostal nerves is a potential method of treating neurologic deficits after spinal cord injury. It appeared to us that the paraspinal splitting approach was potentially an optimal method to perform intercostal nerve harvesting, rerouting, and intercosto-lumbar neurotizations. Ninth, 10th, and 11th intercostal nerve harvesting and rerouting down to L2, L3, and L4 roots were performed on 50 cadavers. The descriptive anatomy and topographic landmarks are reported. The mean total length of intercostal nerve harvested was 17.96 (range, 10-27) cm for the 9th intercostal nerve, 17.14 cm (range, 10-20) for the 10th intercostal nerve and 15.94 cm (range, 10-25) for the 11th intercostal nerve. The length of harvested nerve was not correlated to the size of the trunk. The length of harvested nerve was sufficient to perform lumbar roots neurotizations in the 300 cases of nerve harvesting. Multiple lumbar roots neurotizations with lower intercostal nerves already have been proposed by other authors. In this strategy, the use of the spinal cord and intercostal nerves above the spinal cord lesion avoids the axonal regrowth required via the injured central nervous system. Rerouting intercostals nerves down to the lumbar roots at their exit from the intervertebral foraminae is less invasive that the same procedure performed down to the vertebral canal at the level of the cauda equina as we used in previous protocols. Our anatomic study confirms the advantage of the paraspinal sacrospinalis splitting approach in multiple intercosto-lumbar neurotizations. The approach is quick and easy and allows a good exposure of the nerve roots at the thoracic and lumbar levels. The L2, L3, and L4 roots could be satisfactorily neurotized with this procedure.

Anatomical feasibility of using the ninth, 10th, and 11th intercostal nerves for the treatment of neurological deficits after damage to the spinal cord

The topographic anatomy of the lower intercostal nerves is less well known than that of the upper ones, except for the 12th intercostal nerve. It is possible to use the lower intercostal nerves to perform a neurotization of the lumbar roots. The authors studied the anatomy of the ninth, 10th, and 11th intercostal nerves to obtain descriptive and topographic anatomical data to aid in establishing optimal conditions for harvesting. The ninth, 10th, and 11th intercostal nerves of 50 cadavers were dissected. The proximal part of the nerve in the posterior intercostal space (ISC) was exposed through a posterior approach. The lateral ICS was exposed through a lateral approach, under the latissimus dorsi, which made it possible to harvest the intercostal nerves using a stripping technique. A histological study was conducted on 10 pigs to evaluate the risk of nerve lesions during the stripping procedure. The proximal course of the nerve in the posterior ICS was the same in all cases. The mean total length of the intercostal nerves harvested was 17.96 cm for the ninth, 17.14 cm for the 10th, and 15.94 cm for the 11th intercostal nerve. The harvested nerve length was sufficient in 297 of the 300 cases to perform lumbar root neurotization. The histological study showed no difference between the "open" and the "stripping" techniques regarding the risk of histological lesions in harvested nerves.

Reconstruction of the tongue with reinnervated rectus abdominis musculoperitoneal flaps after hemiglossectomy

Reconstruction of the tongue after glossectomy is a primary objective in the process of improving the life quality of patients suffering from tongue cancer. We developed a new method of surgical reconstruction of the tongue after hemiglossectomy, with reinnervated rectus abdominis musculoperitoneal flaps. The rectus abdominis musculoperitoneal flap consisted of the rectus muscle, posterior rectus sheath, peritoneum, the 10th, 11th and 12th intercostal nerves, and the deep inferior epigastric artery and veins. Five patients underwent immediate reconstruction of the tongue with rectus abdominis musculoperitoneal flaps after hemiglossectomy. The intercostal nerves were anastomosed to the descending branch of the hypoglossal nerve. All transplanted flaps survived. The peritoneum was replaced by squamous epithelium eight weeks after surgery. During the follow-up period, the contour and function of the reconstructed tongues was satisfactory. Our experience indicates that reconstruction of the tongue with rectus abdominis musculoperitoneal flaps after hemiglossectomy is a suitable, cosmetically acceptable method.

Breast reconstruction by means of innervated rectus abdominis myocutaneous flap.

We performed immediate breast reconstruction in 22 patients using rectus abdominis myocutaneous flap accompanied by neurorrhaphy in the past 2 years. In the neurorrhaphy, the 11th intercostal nerve, which controls the sensation of the myocutaneous flap, was anastomosed to the lateral cutaneous branch of the 4th intercostal nerve, which controls the sensation of the breast. Our study included 15 patients, and the postoperative follow-up period was 4 to 24 months, with an average of 14.0 months. For control subjects, there were 16 cases of rectus abdominis myocutaneous flap, whose sensory nerve had not been reconstructed (postoperative follow-up period 11 to 41 months, average 24.1 months). The sensory examination included tests of touch, pain, and temperature. The innervated myocutaneous flap sensation showed gradual recovery at about 6 months after surgery and reached the value of the normal side after about 1 year. In the control subjects, recovery of sensation was not observed at all in the first 10 postoperative months. Then, after more than 1 year, the recovery was gradual and reached the value of the normal side in only some control subjects. Therefore, we consider the present technique useful for recovery of sensation in immediate breast reconstruction.

Periaqueductal gray inhibition of viscerointercostal and galvanic skin reflexes

In adult cats anesthetized with urethan-chloralose, effects of descending volleys from the mesencephalic periaqueductal gray (PAG) upon the viscerointercostal and galvanic skin reflexes were studied. (1) The viscerointercostal reflex (VIR) was evoked by electrical stimulation of the greater splanchnic nerve and was recorded from the 11th, 12th or 13th intercostal nerve. Conditioning stimuli applied to the PAG inhibited the VIR. The inhibition was particularly marked when the nucleus raphe dorsalis (NRD) or its immediately adjacent ventromedial PAG was stimulated. (2) A train of pulses was required in order to produce a recognizable PAG/NRD inhibition of the VIR. When the PAG/NRD was stimulated at 300–500 Hz, stimulation-produced inhibition became more pronounced in parallel with increase in number of pulses in each train and levelled off at about 5 pulses. The most effective frequency of PAG/NRD stimulation was found within this frequency range. (3) Degree of PAG/NRD stimulation-produced inhibition of the VIR was dependent upon the strength of the test stimulus applied to the splanchnic nerve; the weaker the test stimulus, the more marked the inhibition. (4) PAG/NRD stimulation-produced inhibition of the VIR was completely eliminated by bilateral section of the dorsolateral funiculi. The same section enhanced the VIR per se. It was suggested that PAG/NRD stimulation-produced inhibition of the VIR is mediated by descending pathways in the ipsi- as well as contralateral dorsolateral funiculi, and that the VIR per se is tonically inhibited by descending impulses in these pathways. (5) PAG/NRD stimulation inhibited the segmental polysynaptic reflex in the intercostal nerve, but had little effect on the segmental monosynaptic reflex in the same nerve. (6) Intravenous administration of morphine suppressed the VIR. The suppression was antagonized by intravenous naloxone. In contrast, PAG/NRD stimulation-produced inhibition of the VIR was unaffected by intravenous naloxone. (7) Electrical stimulation of the splanchnic nerve evoked the galvanic skin reflex (GSR) from the forepaw pad. The GSR was inhibited by electrical stimulation of the PAG/NRD. The PAG/NRD stimulation-produced inhibition of the GSR was completely eliminated by intravenous administration of naloxone (0.4 mg/kg).

Effects of intercostal nerve blocks on pulmonary mechanics in healthy men.

Bilateral block of the 5th through the 11th intercostal nerves was induced in 16 healthy men. In eight of the men, bupivacaine 0.25% was used and in the other eight, etidocaine 0.5%. Before and after induction of the block flow/volume curves, maximal airway pressures, and pulmonary compliance, were recorded, and helium spirometry and multiple and single breath nitrogen wash-outs were performed. There were no differences between the results in the two groups, and the material was therefore pooled. Total lung capacity was decreased by 4%. There was no increase in residual volume, though the maximal expiratory airway pressure decreased by 7%. There was an 8% decrease in functional residual capacity. Pulmonary recoil appeared to be unchanged, as also did the effort-independent peak expiratory flow rates. According to the pulmonary nitrogen clearance index, the overall pulmonary time constant did not alter, while the slope of the alveolar plateau in the single breath nitrogen wash-out test increased by 9%. The significance of the latter finding is unclear, but it is concluded that the nerve block had no obvious effects on pulmonary mechanics, the changes observed rather being attributable to effects on the chest wall.

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.