Ultrasound versus manipulation to determine an intercostal space for single-port thoracoscopy surgery: a diagnostic accuracy study.

BACKGROUND: Malposition of the intercostal space used for single-port thoracoscopy surgery can lead to problems. This study was to assess the accuracy of point-of-care ultrasound in verifying the position of intercostal space. METHODS: A total of 200 patients, ASA (American Society of Anesthesiologists) physical status I or II, who underwent single-port thoracoscopic lobectomy, were enrolled. After the induction of anesthesia, a thoracic team confirmed the incision position. Firstly, the intercostal space was located by a young resident thoracic surgeon by ultrasound. Secondly, the intercostal space was located by an experienced thoracic surgeon by manipulation. Finally, the investigator verified the location of the intercostal space under direct vision through thoracoscopy, which was recognized as standard method. The time required by ultrasound and manipulation were recorded. RESULTS: The inter-relationships between ultrasound and the standard method and between manipulation and the standard method were consistent. Manipulation positioning showed a sensitivity of 90.6% and specificity of 30% while ultrasound positioning showed a sensitivity of 87.1% and specificity of 60%. The specificity of ultrasound positioning was higher than that of manipulation position. The time required by ultrasound was shorter than that required by manipulation. CONCLUSIONS: Compared with the manipulation method, the ultrasound-guided method could accurately locate the intercostal space. Ultrasound requires less time than manipulation. TRIAL REGISTRATION: ISRCTN10722758. Registered 04 June 2019.

Introduction of a novel ultrasound-guided extrathoracic sub-paraspinal block for control of perioperative pain in Nuss procedure patients.

BACKGROUND: A safe and effective method of multilevel thoracic pain control remains an elusive goal in patients undergoing the Nuss procedure. The aim of our study was to develop a nonopioid centered approach using a novel regional technique as part of a quality improvement initiative. METHODS: The proposed ultrasound-guided technique positions multi-perforated soaker catheter deep to the paraspinal muscles from T2 to T11. The project was conducted in two phases. First, a cadaveric dissection was performed to establish the pathway of spread of local anesthetic in vivo. Second, a pilot double blind randomized control project was conducted to evaluate effectiveness of the technique in ten patients and to derive parameters necessary for the definitive future study. Outcomes were evaluated based on the narcotic requirement, pain scores and functional measures. RESULTS: Placement of the catheters in two cadavers demonstrated reliable positioning in the subparaspinal tissue plane, and multilevel dye spread along the intercostal nerve path. In addition, a potential route of spread toward the paravertebral space along the canal accommodating dorsal ramus of the thoracic nerve was demonstrated. The pilot trial demonstrated a trend in decreased cumulative hydromorphone requirement in comparison to the control group at both 24h (0.19±0.09mg/kg vs. 0.13±0.08mg/kg p=0.72) and 48h (0.37±0.2mg/kg vs. 0.3±0.12mg/kg p=0.37). Functional performance ability was higher in the treatment group on both POD#1 (6.7±1.8 vs. 4.8±1 p=0.0495) and POD#2 (8.9±0.8 vs. 6.5±1.2 p=0.04). Pain scores were similar among the two groups (p=0.96). CONCLUSIONS: We describe a new technique to treat multilevel thoracic pain following the Nuss procedure that is reproducible, safe, allows diminished opioid use and enhances functional recovery.

Determination of the chest wall thicknesses and needle thoracostomy success rates at second and fifth intercostal spaces: a cadaver-based study.

INTRODUCTION: The purposes of this study were to measure the chest wall thicknesses (CWTs) at second intercostal space (ICS) mid-clavicular line (MCL) and fifth ICS MAL directly, and compare the actual success rates of needle thoracostomies (NTs) by inserting a 5-cm-long syringe needle. Predictive values of weight, body mass index (BMI) and CWT were also analyzed. MATERIALS AND METHODS: This study included 199 measurements of 50 adult fresh cadavers from both hemithoraces. Five-centimeter-long syringe needles were inserted and secured. Penetration into the pleural cavity was assessed, and CWTs at 4 locations were measured. Achieved power of this study for the primary aim of CWT comparison from 2nd and 5th ICSs was .94. RESULTS: Overall mean CWTs at 2nd ICS MCL and 5th ICS MAL were measured as 2.46 ± 0.78 and 2.89 ± 1.09, respectively, and 5th ICS MAL was found to be statistically thicker (P = .002). The success rate of NT at 2nd ICS MCL was 87% (95% CI, 80-94), and that at 5th ICS MAL was 78% (95% CI, 70-86; P = .3570). Only 6 (17.1%) of 35 failed NTs had a CWT greater than 5-cm. Needle thoracostomy has failed in 29 (14.9%) of 194 locations, despite a CWT less than 5-cm. Below a weight of 72 kg, BMI of 23 kg/m2, or CWT of 2.4 cm, all NTs were successful. DISCUSSION AND CONCLUSIONS: In this report, we present the largest cadaver-based cohort to date to the best of our knowledge, and we observed a statistically nonsignificant 9% more NT success rate at 2nd ICS at a power of 88% and statistically significant more success rate in males at 5th ICS was (47.7%). We also observed thinner CWTs and higher success rates than previous imaging-based studies. A BMI of 23 kg/m2 or less and weight of 72 kg or less seem to accurately rule-out NT failure in cadavers, and they seem to be better predictors at the bedside.

BRILMA methylene blue in cadavers. Anatomical dissection / BRILMA azul de metileno en cadáveres. Disección anatómica

No disponible

The enigmatic subcostal muscle: Anatomical study with application to spine and chest pain syndromes and avoidance of confusion on imaging.

The aim of this study was to revisit the morphological characteristics of the subcostal muscle and to obtain its morphometric data. One hundred and two sides of the thorax from 51 adult cadavers were used. The total number of subcostal muscles in the 102 specimens was 559. The subcostal muscle commonly comprised an aponeurosis at its superior and inferior attachments. This muscle had a thin band-like shape in 64.2% cases, while in the other 35.8% either its superior or inferior attachment was wider. It was classified into the following four types on the basis of its inferior attachment: in Types I and II it extended to two (79.3%) and three (12.0%) lower ribs, respectively; in Type III it joined adjacent muscles such as the psoas major (2.2%) or quadratus lumborum (0.7%); and in Type IV it was attached to the transverse process (0.4%) or body (3.9%) of the 12th thoracic vertebra and the body of the 1st lumbar vertebra (1.4%). The subcostal muscle was found at the deepest layer of the intercostal space, and mainly presented in the upper and lower parts of the thorax. Its width and height were 18.2 ± 10.9 mm (mean ± SD) and 56.0 ± 13.3 mm, respectively. The distances from the midsagittal line to the superior and inferior attachments of the subcostal muscle were 77.1 ± 13.0 mm and 48.9 ± 13.5 mm, respectively. The results of this study will help to advance current understanding of the subcostal muscle.

Intrinsic transient tracheal occlusion training and myogenic remodeling of rodent parasternal intercostal fibers.

It is recognized that diaphragm muscle plasticity occurs with mechanical overloads, yet less is known about synergistic parasternal intercostal muscle fiber remodeling. We conducted overload training with intrinsic transient tracheal occlusion (ITTO) exercises in conscious animals. We hypothesized that ITTO would yield significant fiber hypertrophy and myogenic activation that would parallel diaphragm fiber remodeling. Sprague-Dawley rats underwent placement of a tracheal cuff and were randomly assigned to receive daily 10 min sessions of conscious ITTO or observation (sham) over 2 wk. After training, fiber morphology, myosin heavy chain (MHC) isoform composition, cross-sectional area, proportion of Pax7-positive nuclei, and presence of embryonic MHC (eMHC) were quantified. Type IIx/b fibers were 20% larger after ITTO training than with sham training (ITTO: 4,431 +/­ 676 µm2, sham: 3,689 +/­ 400 µm2, p < 0.05), and type I fibers were more prevalent after ITTO (p < 0.01). Expression of Pax7 was increased in ITTO parasternals and diaphragm (p < 0.05). In contrast, the proportion of eMHC-positive fibers was increased only in ITTO parasternals (1.2% [3.4%­0.6%], sham: 0% [0.6%­0%], p < 0.05). Although diaphragm and parasternal type II fibers hypertrophy to a similar degree, myogenic remodeling appears to differ between the two muscles.

The posterior intercostal vein: a thermoregulatory gateway to the internal vertebral venous plexus.

The internal vertebral venous plexus (IVVP) plays a putative role in thermoregulation of the spinal cord. Cold cutaneous venous blood may cool, while warm venous blood from muscles and brown fat areas may warm the spinal cord. The regulating mechanisms for both cooling and warming are still unknown. Warm venous blood mainly enters the IVVP via the intervertebral veins. In the thoracic area these veins are connected to the posterior intercostal veins. In this study, anatomical structures were investigated that might support the mechanisms by which warmed venous blood from the intercostal muscles and the recently described paravertebral patches of brown adipose tissue are able to drain into the vertebral venous plexus. Therefore, tissue samples from human cadavers (n = 21) containing the posterior intercostal vein and its connections to the IVVP and the azygos veins were removed and processed for histology. Serial sections revealed that the proximal parts of the posterior intercostal veins contained abundant smooth muscle fibers at their opening into the azygos vein. Furthermore, the walls of the proximal parts of the posterior intercostal veins contain plicae that allow the vessel to dilate, thereby allowing it to serve as a pressure chamber. It is suggested that a cold induced closure of the intercostal/azygos opening can result in retrograde blood flow from the proximal posterior intercostal vein towards the IVVP. This blood flow would be composed of warm blood from the paravertebral brown adipose tissue and blood containing metabolic heat from the muscles draining into the intercostal veins.

Do ribs actually have a bare area? A new analysis.

Recognition of macroscopic rib pathology requires an in-depth understanding of anatomy, especially of the attachment of muscle tendons and aponeuroses. Distinguishing periosteal reaction from residual aponeurotic tissues and the rugosity associated with muscle attachments, requires knowledge of these structures. The ribs of twenty cadavers were examined to establish the distribution of muscle attachments and aponeuroses, and their variations. A unique observation was that the entire rib surface is covered by tendon attachments and aponeuroses, without evidence of bare areas that are so prominent in other parts of the skeleton. Discrepancies between rugose regions and the extent of tendon attachments were occasionally noted, with the tendons or aponeuroses extending beyond the areas of attachments of the muscle fibers. Variable dessication of aponeurotic tissues can compromise appearance of normal bone, and may be responsible for past overdiagnosis of periosteal reaction.

Adherent primary cultures of mouse intercostal muscle fibers for isolated fiber studies.

Primary culture models of single adult skeletal muscle fibers dissociated from locomotor muscles adhered to glass coverslips are routine and allow monitoring of functional processes in living cultured fibers. To date, such isolated fiber cultures have not been established for respiratory muscles, despite the fact that dysfunction of core respiratory muscles leading to respiratory arrest is the most common cause of death in many muscular diseases. Here we present the first description of an adherent culture system for single adult intercostal muscle fibers from the adult mouse. This system allows for monitoring functional properties of these living muscle fibers in culture with or without electrical field stimulation to drive muscle fiber contraction at physiological or pathological respiratory firing patterns. We also provide initial characterization of these fibers, demonstrating several common techniques in this new model system in the context of the established Flexor Digitorum Brevis muscle primary culture model.

Relevant surgical anatomy of the chest wall.

The chest wall, like other regional anatomy, is a remarkable fusion of form and function. Principal functions are the protection of internal viscera and an expandable cylinder facilitating variable gas flow into the lungs. Knowledge of the anatomy of the whole cylinder (ribs, sternum, vertebra, diaphragm, intercostal spaces, and extrathoracic muscles) is therefore not only important in the local environment of a specific chest wall resection but also in its relation to overall function. An understanding of chest wall kinematics might help define the loss of function after resection and the effects of various chest wall substitutes. Therefore, this article is not an exhaustive anatomic description but a focused summary and discussion.

Radiological review of intercostal artery: Anatomical considerations when performing procedures via intercostal space.

INTRODUCTION: The aim of this study was to closely examine the course of the intercostal arteries within the intercostal spaces particularly with regard to where the arteries were located in relation to their adjacent ribs. The degree of tortuosity of the arteries was also examined, along with anatomical differences in different age groups. METHODS: A total of 81 patients between the age of 30 and 90 years who had underwent a CT examination of the chest for any indication were included in the study. All studies were performed on a dual source 64 slice CT (Siemens Definition Erlangen Germany). Analysis of the intercostal arteries was performed on a CT workstation using volume rendered 3D reconstructions F, or each patient the 10'n intercostals pacesb ilaterally were examined for the course and tortuosity of the intercostal arteries. RESULTS: The ICA is located relatively inferiorly in the intercostal space at costovertebral junction and it gradually becomes more superiorly positioned within the intercostal space it as courses laterally. This finding was consistent in all age groups. In addition, analysis of the data demonstrated increasing intercostal artery tortuosity with advancing age. CONCLUSION: In this study we have examined the course of the posterior intercostal arteries using MDCT. This study confirms the classical description of the course of ICA. We have shown that in the medial chest, posteriorly, the artery is located in the inferior half of the intercostal space. As it moves away from the costovertebral junction it travels closer to the inferior border of the rib above and reaches the intercostal groove. We have also shown that the artery tends to be more tortuous in elderly patients, decreasing the area of "safe" space for interventions. Both of these findings are relevant to radiologists and non-radiologists performing interventional procedures via the intercostal space.

Ultrasound-guided thoracic paravertebral blockade: a cadaveric study.

BACKGROUND: Multiple approaches to the paravertebral space have been described to produce analgesia after thoracic surgery. Ultrasound-guided regional anesthesia has the potential to improve efficacy and reduce complications via real-time visualization of the paravertebral space, surrounding structures, and the approaching needle. We compared a single- versus dual-injection technique for ultrasound-guided paravertebral blockade in a cadaver model, evaluating the spread of contrast dye and location of a catheter. METHODS: Thirty paravertebral injections and 20 catheter placements were performed on 10 fresh cadavers. The paravertebral space was identified using an ultrasound probe in the transverse plane using a linear transducer. An in-plane needle approach was used. Using analine contrast dye, a single 20-mL injection at T6-7 on one side and a dual-injection technique of 10 mL at T3-4 and T7-8 on the contralateral side were performed on each cadaver, followed by insertion of a catheter through the needle. The cadaver was then dissected to evaluate spread of contrast dye and catheter location. RESULTS: The paravertebral space was easily identified with ultrasound on each cadaver. Contrast dye was seen to surround somatic and sympathetic nerves in the paravertebral, intercostal, and epidural spaces. Contrast dye was present in 19 of 20 paravertebral spaces over 3 to 4 segments (range, 0-10) with no significant differences between single- and dual-injection techniques. Contrast dye spread more extensively across intercostal segments with 4.5 spaces (range, 2-10) covered with a single injection and 6 spaces (range, 2-8) covered with a dual-injection technique (P = 0.03). There was epidural spread of contrast in 40% of paravertebral injections in both single- and dual-injection techniques. Catheters were located in the paravertebral space (60%), prevertebral space (20%), and epidural space (5%). CONCLUSIONS: Transverse in-plane ultrasound-guided needle insertion into the thoracic paravertebral space is both feasible and reliable. However, paravertebral spread of contrast is highly variable with intercostal and epidural spread likely contributing significantly to the analgesic efficacy. A dual-injection technique at separate levels seems to cover more thoracic dermatomes because of greater segmental intercostal spread (rather than paravertebral spread) than a single-injection approach. Catheters are located in nonideal positions in 40% of cases using this in-plane technique.

Ultrasound anatomy of the cervical paravertebral space: a preliminary study.

PURPOSE: The aim of the study was to examine the ultrasound anatomy of the cervical paravertebral space in order to facilitate the implementation of sonographically guided regional anesthesia techniques for this region. METHODS: Twenty volunteers were recruited, and the anatomic components of the cervical paravertebral space were sonographically examined. The transducer was positioned in the axial and coronal plane at the posterior cervical triangle. The cervical transverse processes with their respective nerve roots, the deep cervical fascia and the paravertebral muscles were identified. RESULTS: There was excellent visualization of the C-3, C-4, C-5, C-6 and C-7 transverse processes in all cases. Excellent visualization of the scalene muscles, vertebral artery and deep cervical fascia was also achieved in all cases. Visualization of the levator of scapula muscle was difficult in 9 and excellent in 11 out of the 20 cases. In all cases, visualization of the C-1, C-2 and C-3 nerve roots was unfeasible. The identification of the C-4 nerve root was excellent in 3, difficult in 6 and unfeasible in 11 out of the 20 cases. The C-5, C-6 and C-7 nerve roots were excellently identified in all cases. The C-8 nerve root was identified only in 8 of the 20 cases. The cervical nerve roots also showed high variation, dividing into more than one branch as they exited the cervical transverse processes. CONCLUSION: Cervical paravertebral anatomy can be depicted with ultrasound imaging techniques. This could be highly clinically significant for the implementation of regional anesthesia techniques.

Diagrammatic analysis of the respiratory action of the diaphragm.

During isolated phrenic nerve stimulation, the muscles of the diaphragm shorten by 40-50% of their optimal length, and the force in the muscle and transdiaphragmatic pressure (Pdi) depend on the final muscle length. The muscle shortening depends on the load imposed on the diaphragm by pleural and abdominal pressures during a particular maneuver. The mechanics of the interaction between the diaphragm and the load is well understood, but the force-length properties of the diaphragm are nonlinear, and an algebraic analysis of the interaction is clumsy. Here we describe a graphical analysis of the interaction. The variable muscle length is transformed into an equivalent variable, i.e., volume displaced by the diaphragm (Vdi), to obtain the characteristic line for the diaphragm, a graph of Pdi vs. Vdi for a given level of activation. The load is described by the same variables. Therefore, load lines can be drawn on the same graph, and the equilibrium point for the diaphragm is given by the intersection of the load line with the characteristic line of the diaphragm. Graphical analyses of the volume dependence of the respiratory effects of diaphragm and intercostal muscle activation and for the interaction between them are shown.

The anterior to midaxillary line between the 4th or 5th intercostal space (Buelau position) is safe for the use of thoracostomy tubes in preterm and term infants.

OBJECTIVES: Thoracostomy tubes are widely used in neonatology. Complications occurred significantly more frequently in infants, especially neonates, than in adults. Principally, the access is the modified Buelau position which takes place in the anterior axillary line at the 4th or 5th intercostal space above the margin of the ribs. AIM: This study seeks to determine the characteristics and topographic conditions of the anatomical structures at the ventral and lateral thoracic wall in the preterm and term neonate. BACKGROUND: Fifteen formalin-fixed stillborns were prepared (nine male, six female, 28-43 weeks gestational age). METHODS/MATERIALS: The anatomical preparation involved the complete thoracic wall region. RESULTS: In all preparations, a venous vessel was detected at the lateral wall and was identified as v. thoracoepigastrica without accompanying artery. Arteria (a.) and vena (v.) thoracica interna were regularly found close to the sternal plate on both sides between rib and fascia. With increasing gestational ages the course of the v. thoracoepigastrica varied significantly between the left and right thoracic wall. It was demonstrated that the v. thoracoepigastrica regularly arose within the abdominal or thoracic subcutaneous fat and drained into the v. subclavia. The variance between its course was almost 5-12 mm to the lateral or medial side. At both thoracic sides, no other organs or organ structures except lung parenchyma could be detected when using the Buelau position. CONCLUSIONS: The anterior to midaxillary line between the 4th or 5th intercostal space (Buelau position) is safe for the use of thoracostomy tubes in preterm and term infants.

Anatomical study of pectoral intercostal perforators and clinical study of the pectoral intercostal perforator flap for hand reconstruction.

BACKGROUND: The authors have used pectoral intercostal perforator flaps to reconstruct burned or injured hands by staged transfer. This flap is designed with a narrow skin pedicle that includes intercostal perforators from the fifth to eighth intercostal spaces, with a wide flap area that lies on the upper abdomen. The distal area is thinned down to the subdermal vascular network level; thus, such flaps are called "superthin flaps" or subdermal vascular network flaps. In this article, the authors discuss the arterial networks associated with this flap and present clinical cases. METHODS: The authors performed an anatomical study using 13 cadavers to obtain angiograms and dissect the anterior chest and abdominal region. Clinically, the authors retrospectively analyzed 21 cases over 13 years. RESULTS: Anatomically, the anterior intercostal regions could be divided into three segments with regard to vascular supply to the skin and subcutaneous layer. In particular, in the fifth to eighth intercostal spaces, perforators communicated with one another to form a "latticework" pattern. In addition, the vascular territories participating in the pectoral intercostal perforator flap, that is, the intercostal perforators, the superior epigastric artery system, and the deep inferior epigastric artery system, linked with each other through choke vessels. In the authors' clinical cases, functional and aesthetic results were satisfactory. CONCLUSIONS: The pectoral intercostal perforator flap was supported by the arterial networks among perforators in the intercostal spaces and in the upper abdomen. This flap is one useful method for reconstruction of the hand region, providing good quality in terms of thinness and texture.

Menin expression modulates mesenchymal cell commitment to the myogenic and osteogenic lineages.

Menin plays an established role in the differentiation of mesenchymal cells to the osteogenic lineage. Conversely, whether Menin influences the commitment of mesenschymal cells to the myogenic lineage, despite expression in the developing somite was previously unclear. We observed that Menin is down-regulated in C2C12 and C3H10T1/2 mesenchymal cells when muscle differentiation is induced. Moreover, maintenance of Menin expression by constitutive ectopic expression inhibited muscle cell differentiation. Reduction of Menin expression by siRNA technology results in precocious muscle differentiation and concomitantly attenuates BMP-2 induced osteogenesis. Reduced Menin expression antagonizes BMP-2 and TGF-beta1 mediated inhibition of myogenesis. Furthermore, Menin was found to directly interact with and potentiate the transactivation properties of Smad3 in response to TGF-beta1. Finally in concert with these observations, tissue-specific inactivation of Men1 in Pax3-expressing somite precursor cells leads to a patterning defect of rib formation and increased muscle mass in the intercostal region. These data invoke a pivotal role for Menin in the competence of mesenchymal cells to respond to TGF-beta1 and BMP-2 signals. Thus, by modulating cytokine responsiveness Menin functions to alter the balance of multipotent mesenchymal cell commitment to the osteogenic or myogenic lineages.