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PubMed1995

Architecture and function of the extravascular fluid pathway: special reference to the macula cribriformis in the diaphragm.

Silver staining, transmission electron microscopy (TEM) and scanning electron microscopy (SEM) have been used to delineate the structure and function of the extravascular fluid pathway of the diaphragm of monkeys, rats, mice and rabbits. The submesothelial connective tissue was examined by SEM using the NaOH maceration method. A sieve-like structure, the macula cribriformis, was found in the submesothelial connective tissue on the peritoneal side of both the muscular and tendinous portions. The macula cribriformis, which consisted of densely-packed collagen fibrils, was oval, spindle and polygonal in shape and ranged in diameter from 20 to 300 microns with 5-300 foramina (3-15 microns). The macula cribriformis was located between peritoneal mesothelial cells with stomata and subperitoneal lymphatic capillaries. Intraperitoneally-injected latex particles were carried into the diaphragmatic lymphatic capillaries via the peritoneal stomata and the foramina of the macula cribriformis. These results support the hypothesis proposed by Kihara (Okajimas Fol Anat Jpn 28: 601-621, 1956) that the macula cribriformis is a pre-lymphocapillary pathway, one of the extravascular fluid pathways.

Animals↗

PubMed1975

Respiratory function in esophageal hiatus hernia. II. Regional lung function.

64 subjects with hiatus hernia (34 sliding, 22 mixed, and 8 of paraesophageal variety) were divided into 3 groups according to the transverse diameter of the thoracic loculus and examined by 133Xe-radio-spirometry in the supine position. 48 subjects (22 sliding, 18 mixed, and 8 or paraesophageal variety) showed a significant reduction in the regional ventilation, perfusion or lung volume. Significant correlations were found between the diameter of the thoracic loculus and the reduction in these vairables of the affected lung.

Adult↗

PubMed2001

Down-regulation of regulatory proteins for differentiation and proliferation in murine fetal hypoplastic lungs: altered mesenchymal-epithelial interactions.

We compared proliferation (growth) and differentiation (development) related proteins in normal and hypoplastic fetal murine lungs. The hypoplastic lungs were created in CD-1 fetal mice by nitrofen exposure (25 mg per pregnant mouse given intragastrically on gestational day 8 [Gd8]), as published earlier. The lungs were harvested at Gd14, 16, 19 and from neonates. Immunoblot analyses were carried out for transcription factors (oncogenic proteins, nuclear receptor, and transmembrane receptor proteins) in severely hypoplastic murine fetal lungs with coexistent diaphragmatic hernia, and results were compared with those derived from normal lungs of equivalent age. These proteins have proposed roles in the regulation of proliferation and differentiation processes of fetal lungs. We have shown that the product of the oncogene c-myc was reduced in hypoplastic lungs at all stages of gestation, whereas c-Fos protein levels were variable. These proteins are known to regulate transcription of various developmental proteins, such as those responsible for proliferation and differentiation. Further, the nuclear transcription factors thyroid transcription factor-1 (TITF-1) and glucocorticoid receptor (GR) were reduced, and thyroid hormone receptor (TR) and retinoic acid receptors (RARs) were inhibited in severely hypoplastic lungs compared to normal lungs of equivalent gestational stage, except in neonatal lungs, where signals for RARs were seen. TITF-1 is known to localize in bronchial epithelial cells in developing lungs. It is restricted to type II pneumocytes with gestational development in the normal lungs and regulates surfactant proteins. Earlier, we have reported that surfactant proteins are reduced in hypoplastic lungs. In the current study, reduced GR and TITF-1 proteins may play a role in reducing surfactant proteins in the hypoplastic lungs. The significant inhibition in TR and RARalpha in the severely hypoplastic lungs reflects on affected epithelial cell maturation and alveolar formation, respectively. Altered RARbeta levels correlate with affected lung growth and branching morphogenesis of nitrofen-exposed lungs. A transmembrane receptor protein EGFR was reduced in hypoplastic lungs, suggesting the involvement of altered mesenchymal-epithelial signal transduction pathways. We conclude (1) Our data suggest altered levels of various nuclear transcription factors in the murine fetal hypoplastic lungs; (2) Reduced levels TITF-1 protein in hypoplastic lungs may have caused the functional immaturity of distal lung, immature airways and thus may affect overall differentiation of lungs. These results correlated with low levels of surfactant proteins in these lungs; (3) TR and RAR inhibition indicate their roles through reduced or retarded proliferation and differentiation processes in the severely hypoplastic lungs; (4) GR down-regulation in developing fetal murine hypoplastic lungs indicate delayed development, and GR up-regulation in affected neonates may be induced by stress/stretch caused at birth due to air-breathing; (5) Down- regulation of EGFR indicate altered mesenchymal-epithelial interactions and possible influence on lung proliferation and differentiation.

Animals↗

PubMed1989

Intensive care for children after orthotopic liver transplantation.

We report our experience in the management of children after orthotopic liver transplantation (OLT). From 03/84 to 04/87 50 patients (pts) were transplanted. Mean age was 4 3/12 years (8/12 to 13 2/12) and mean body weight 14.7 kg (5.8 to 40). Hospital mortality was 14%. Problems related to the surgery included: Abdominal complications: bleeding (8 pts), infection (18 pts), ascites and fistula (1 pt), need for secondary abdominal surgery (10 patients). Respiratory problems: lobar atelectasis (11 pts), right diaphragmatic paralysis (2 pts) and right pleural effusion (11 pts). Problems related to immunosuppression included: Bacterial infection (29 pts) fungal infection (5 pts), one patient died of disseminated cytomegalovirus infection. Side effect of cyclosporin A (CsA) were systemic blood hypertension (S.B.H.) (47 pts), sinusal bradycardia (37 pts), associated to SBH (24 pts), hypertensive encephalopathy (2 pts). Generalized seizures (2 pts in the absence of SBH). Renal side effects of CsA were hypercreatininemia, decreased sodium bicarbonate and hyperkaliemia. The nephrotoxicity of CsA was favoured by the use of other nephrotoxic drugs such as aminoglycosides, amphotericin B. Edematous pancreatitis was observed in 3 patients and related to the use of large doses of steroids. Problems related to the functioning of the graft included: Primary non-function of the graft (4 pts), hepatic artery thrombosis (8 pts) and severe acute rejection unresponsive to therapy (1 pt); these situations needed to be recognised early in order to organize a second OLT. Other causes of hepatic dysfunction were: portal vein thrombosis (1 pt), biliary tract obstruction (2 pts), angiocholitis (3 pts), right hepatic lobe necrosis (2 pts). Acute hepatic insufficiency in 7 children.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMedDate not supplied

Mechanisms of the non-neurotransmitter actions of acetylcholine in the neuromuscular apparatus.

Experiments on isolated phrenic-diaphragmatic preparations from rats showed that low acetylcholine concentrations increase the work capacity of exhausted muscle by increasing the level of evoked quantum transmitter release; acetylcholine also induced hyperpolarization of muscle fiber membranes. The effects of acetylcholine persisted for long periods of time. The modulating actions of acetylcholine are mediated by structures with different pharmacological characteristics from those of typical n- and m-cholinoreceptors; these mechanisms involved ouabain-sensitive isoforms of Na+,K+-ATPase and, perhaps, membrane K+ channels. The data obtained here support the possible existence of long-term neuronal regulation of the efficiency of neuromuscular transmission involving non-quantal acetylcholine, these mechanisms presumably developing differently in muscle fibers with different functional characteristics and abilities to adapt to physiological loading.

Acetylcholine↗

PubMed1998

Systolic ventricular dysfunction causes selective diaphragm atrophy in rats.

In order to examine the relative impairment of the diaphragm and other skeletal muscles in systolic ventricular dysfunction (VD), their structure and function were compared between rats with VD induced by left coronary artery ligation (n = 17) and sham-operated rats (Co, n = 10). In addition, in an attempt to unravel the mechanism of the observed impairment, we examined alterations in insulin-like growth factor-I (IGF-I) serum levels and IGF-I expression in the liver, diaphragm, and gastrocnemius. In a second series of rats (VD, n = 5 and Co, n = 5) hemodynamic measurements were performed. All measurements were performed 3 mo after the operation. Infarct size averaged 32 +/- 10 and 44 +/- 20% in the two series, respectively (NS). Hemodynamic measurements revealed a decrease in left ventricular peak systolic pressure of 19% (p < 0. 05). Significant diaphragm atrophy (weight: 622 +/- 52 mg in VD versus 750 +/- 54 mg in Co, p < 0.0005), without alterations in diaphragm contractile properties was present in VD animals. For all animals combined, the reduction in diaphragm weight was related to infarct size (r = -0.74, p < 0.001). No alterations were observed in the other inspiratory and peripheral muscles. ATPase staining of the diaphragm showed atrophy of type I and type IIx/b fibers, their cross-sectional area (CSA) being reduced by 13 and 16%, respectively (p < 0.05). There were no signs of myopathic alterations. IGF-I expression was increased by 55% in the diaphragm of rats with VD (p < 0.05). IGF-I expression in the liver and gastrocnemius and serum IGF-I levels were unaltered. These data suggest the presence of compensatory mechanisms aimed at minimizing diaphragmatic fiber atrophy. We conclude that systolic VD caused: (1) selective diaphragm atrophy, which was related to infarct size; (2) a decrease in diaphragm type I and IIx/b CSA not associated with myopathic changes; (3) an increase in the IGF-I mRNA content of the diaphragm. The selective diaphragm involvement in the present study may be related to the moderate degree of ventricular dysfunction induced.

Adenosine Triphosphatases↗

PubMed1984

Mechanical arrangement of costal and crural diaphragms in dogs.

To assess the mechanical arrangement of the costal and crural parts of the diaphragm, we studied changes in diaphragmatic length with piezoelectric crystals in 17 supine anesthetized dogs. During control resting inspiration, the crural part usually shortened more and earlier than the costal part. After phrenicotomy, the crural part always lengthened during inspiration, whereas the costal part shortened or lengthened. These interanimal differences disappeared after opening of the abdomen; the costal part then always lengthened during inspiration. During stimulation of one part, the relaxed nonstimulated part always lengthened. However, when compared with the relationship between length and transdiaphragmatic pressure (Pdi) obtained during passive deflation, the lengthening of the relaxed part during stimulation of either part was small. This difference between predicted and measured Pdi-length relationship decreased in magnitude as lung volume increased above functional residual capacity (FRC) and increased as residual volume was approached. These results indicate that 1) even during quiet breathing the diaphragm in the dog is not a single functional entity; 2) at FRC the costal and crural portions of the diaphragm behave as if they were mechanically arranged partly in parallel and partly in series; and 3) they gradually move into a pure mechanical series arrangement as lung volume increases.

Animals↗

PubMed1979

[Surgical treatment of hiatal hernias (author's transl)].

The diagnosis "hiatal hernia" does not equate with surgery, but if it is combined with disturbed function of the gastrooesophageal transitional area or reflux oesophagitis it needs therapy. Therefore, the diagnosis has to be made with care. Based on over 800 cases the intraluminal layered pH-metry proved to be a very helpful method. Paraoesophageal hernias should be surgically treated due to their tendency towards strangulation and incarceration. From 1956 to 1976 287 patients suffering from hiatal hernia were operated on, mortality rate and late results are analysed.

Gastroesophageal Reflux↗

PubMed1993

Differential actions of brevetoxin on phrenic nerve and diaphragm muscle in the rat.

The mechanism of inhibition of skeletal muscle function by brevetoxin (PbTX-3) was examined in vitro in the rat phrenic nerve-diaphragm preparation. PbTX-3 in low concentrations (< 0.06 microM) preferentially blocked conduction in the phrenic nerve without altering the resting membrane potential of the muscle fibers. Endplate potential failure occurred in an all-or-none fashion in the presence of PbTX-3 (> 0.06 microM). An increase in the frequency of miniature endplate potentials resulting from nerve terminal depolarization was observed only after endplate potential failure. Higher concentrations of toxin (> 0.3 microM) depressed directly-elicited muscle twitches and produced significant muscle membrane depolarization. Tetrodotoxin was effective in reversing membrane depolarization and alterations in MEPP frequency caused by PbTX-3. These findings suggest that diaphragmatic failure in PbTX-3 is primarily caused by a block of impulse conduction in the phrenic nerve due to a higher sensitivity of nerve than muscle membrane to the toxin.

Action Potentials↗

PubMed1999

Chest physiotherapy in cystic fibrosis: improved tolerance with nasal pressure support ventilation.

OBJECTIVE: Chest physiotherapy (CPT) is an integral part of the treatment of patients with cystic fibrosis (CF). CPT imposes additional respiratory work that may carry a risk of respiratory muscle fatigue. Inspiratory pressure support ventilation (PSV) is a new mode of ventilatory assistance designed to maintain a constant preset positive airway pressure during spontaneous inspiration with the goal of decreasing the patient's inspiratory work. The aim of our study was 1) to evaluate respiratory muscle fatigue and oxygen desaturation during CPT and 2) to determine whether noninvasive PSV can relieve these potential adverse effects of CPT. METHODS: Sixteen CF patients in stable condition with a mean age of 13 +/- 4 years participated to the study. For CPT, we used the forced expiratory technique (FET), which consisted of one or more slow active expirations starting near the total lung capacity (TLC) and ending near the residual volume. After each expiration, the child was asked to perform a slow, nonmaximal, diaphragmatic inspiration. After one to four forced breathing cycles, the child was asked to cough and to expectorate. A typical 20-minute CPT session consisted of 10 to 15 FET maneuvers separated by rest periods of 10 to 20 breathing cycles each. During the study, each patient received two CPT sessions in random order on two different days, at the same time of day, with the same physiotherapist. During one of these two sessions, PSV was provided throughout the session (PSV session) via a nasal mask using the pressure support generator ARM25 designed for acute patients (TAEMA, Antony, France). The control session was performed with no nasal mask or PSV. Both CPT sessions were performed without supplemental oxygen. Lung function and maximal inspiratory pressures (PImax) and expiratory pressures (PEmax) were recorded before and after each CPT session. RESULTS: Mean lung function parameters were comparable before the PSV and the control sessions. Baseline pulse oximetry (SpO2) was significantly correlated with the baseline vital capacity (% predicted) and forced expiratory volume in 1 second (FEV1) (% predicted). PSV was associated with an increase in tidal volume (Vt) from 0.42 +/- 0.01 liters to 1.0 +/- 0.02 liters. Respiratory rate was significantly lower during PSV. SpO2 between the FET maneuvers was significantly higher during PSV as compared with the control session. SpO2 decreases after FET were significantly larger during the control session (nadir: 91.8 +/- 0. 7%) than during the PSV session (93.8 +/- 0.6%). Maximal pressures decreased during the control session (from 71.9 +/- 6.1 to 60.9 +/- 5.3 cmH2O, and from 85.3 +/- 7.9 to 77.5 +/- 4.8 cmH2O, for PImax and PEmax, respectively) and increased during the PSV session (from 71.6 +/- 8.6 to 83.9 +/- 8.7 cmH2O, and from 80.4 +/- 7.8 to 88.0 +/- 7.4 cmH2O, for PImax and PEmax, respectively). The decrease in PEmax was significantly correlated with the severity of bronchial obstruction as evaluated based on baseline FEV1 (% predicted). Forced expiratory flows did not change after either CPT session. The amount of sputum expectorated was similar for the two CPT sessions (5.3 +/- 5.3 g vs 4.6 +/- 4.8 g after the control and PSV session, respectively; NS). Fifteen patients felt less tired after the PSV session. Ten patients reported that expectoration was easier with PSV, whereas 4 did not note any difference; 2 patients did not expectorate. Nine patients expressed a marked and 5 a small preference for PSV, and 2 patients had no preference. The physiotherapists found it easier to perform CPT with PSV in 14 patients and did not perceive any difference in 2 patients. DISCUSSION: Our study in CF children shows that respiratory muscle performance, as evaluated based on various parameters, decreased after CPT and that significant falls in oxygen saturation occurred after the FET maneuvers despite the quiet breathing periods between each FET cycle. These unwanted effects of CPT were

Adolescent↗

PubMed1975

Clinical assessment of left ventricular regional contraction patterns and ejection fraction by high-resolution gated scintigraphy.

An improved, noninvasive, radionuclidic, gated blood-pool imaging technique has been developed for clinical analysis of regional contraction abnormalities of the left ventricle and determination of ejection fraction. The principal innovations include high-resolution collimation, higher information density, improved method for dynamic aortic-mitral-diaphragmatic border delineation, accurate selection of the endsystolic gating interval through the use of the phonocardiogram, and accurate end-diastole by on-line gating immediately following the electrocardiographic QRS. The results of scintigraphic studies were compared with selective radiopaque cineangiographic findings in 27 patients with cardiac disease; excellent correlations of ejection fractions (r = 0.93) and abnormal contraction patterns (17/17 patients) were demonstrated. In addition, the clinical usefulness in evaluating ventricular performance was demonstrated in 79 patients with acute and chronic coronary artery disease. This radionuclidic technique allowed assessment of reversibility of segmental dyssynergy by the response to nitroglycerin in 20 patients. These findings demonstrate the validity of this improved radionuclidic technique in the atraumatic quantification of ventricular function and suggest its usefulness in a variety of clinical conditions.

Acute Disease↗

PubMed2003

Effective long-term left atrial pacing using regular screw-in leads implanted within the coronary sinus.

Passive-fixation leads positioned inside the coronary sinus (CS) have been found to be effective in LA pacing and sensing, but their use is limited by a high incidence of early and late dislodgment. Since anatomic studies have shown that the proximal part of the CS is surrounded by a relatively thick musculature, the feasibility, safety, and efficacy of acute and chronic coronary sinus pacing via regular screw-in leads positioned within the first centimeters of the CS were evaluated as compared to passive-fixation leads. Thirty-three patients (21 men, age 62 +/- 10 years) underwent dual chamber pacemaker implantation with LA pacing obtained via passive-fixation leads (7 patients) or regular screw-in leads (26 patients). The former approach was prematurely abandoned because of a high rate of acute and late lead dislodgment (42%). The chronic pacing threshold was 1.7 +/- 1.0 V at 0.67-ms pulse width and 1.47 +/- 1.3 V at 0.5-ms pulse width for passive- and active-fixation leads, respectively. In the CS active-fixation lead group, no postoperative pericardial effusion, CS lead dislodgment, nor diaphragmatic stimulation were observed. In this last group, steroid eluting leads (14 patients) have a statistically lower pacing threshold than noneluting steroid leads (12 patients) (0.88 +/- 0.23 vs 2.29 +/- 1.68 V, P = 0.011) at long-term follow-up. The use of regular screw-in leads implanted within the CS allows effective and safe long-term LA pacing without risk of dislodgment.

Atrial Function, Left↗

PubMed1987

Transcutaneous respiratory electromyographic monitoring.

The integrated diaphragm electromyogram (EMG) signal reflects function from the inspiratory centers to the neuromuscular junction. The feasibility and potential value of transcutaneous diaphragm electromyography (tcEMG) was confirmed in a group of infants using two prototype respiratory EMG monitors. Infants were monitored continuously for periods ranging from hours to days. One hundred were monitored for clinical reasons, looking for disordered respiratory behavior, while 47 were studied for technical/experimental reasons. Reliable measurements of diaphragm EMG activity were obtained, provided fully shielded electrode cables were used. Measurements in 28 ventilated infants and one adult confirmed that, unlike impedance and other non-electrophysiologic measures, tcEMG monitoring is not contaminated by ventilator-induced respiratory movements. The potential value of tcEMG monitoring in ventilated subjects is exemplified by illustrations of: diaphragmatic inactivity from phrenic nerve injury, inadequate central drive, and neuromuscular block; augmented expiratory muscle activity; and progressive increase in inspiratory diaphragmatic activity in the presence of a tension pneumothorax. TcEMG monitoring should prove a worthwhile addition to the available noninvasive respiratory monitoring techniques.

Diaphragm↗

PubMed1993

Multicenter comparison of conventional venoarterial access versus venovenous double-lumen catheter access in newborn infants undergoing extracorporeal membrane oxygenation.

A multicenter trial was designed to compare standard venoarterial (VA) access versus single-catheter, venovenous access using the double-lumen catheter (VV-DLC) for newborns with respiratory failure undergoing extracorporeal membrane oxygenation (ECMO). Twenty-seven ECMO centers participated, each submitting data from the center's most recent VA cases, and data from VV-DLC cases completed upon entering the study. Data from 135 VA ECMO cases and 108 VV-DLC cases were submitted. All diagnoses resulting in neonatal respiratory failure were submitted, including patients with congenital diaphragmatic hernia (24 patients VA bypass, 11 patients VV-DLC bypass). Overall survival in patients undergoing VA bypass was 87%, while survival in patients undergoing VV-DLC bypass was 95%. Eleven patients required conversion from VV-DLC bypass to VA bypass because of insufficient support--10 of these patients survived (91% survival). Average bypass time for newborns undergoing VA bypass was 132 +/- 7.4 hours versus 100 +/- 5.1 hours for those undergoing VV-DLC bypass. Neurologic complications were more common in the VA bypass patients, although the VV patients were more stable. Hemorrhagic, cardiopulmonary, and mechanical complications, other than kinking of the DLC, occurred with approximately equal frequency in each group. In conclusion, in newborns with adequate cardiac function, venovenous ECMO using the DLC can provide the same level of support as conventional VA ECMO, without ligation of the carotid artery.

Carotid Artery, Common↗

PubMed1981

Left ventricular fibre architecture in man.

In order to investigate the possibility of regional variation of ventricular structure, 25 normal postmortem human hearts were studied by inspection of cavity shape and subepicardial fibre orientation, by dissection, and by the histology of sections in two orthogonal planes. Ventricular architecture was complex. Inlet and outlet long axes were separated by 30 degrees in the left ventricle. In the right the corresponding figure was 90 degrees. The thickest part of the left ventricular wall was at the base. At the apex there was potential endo- and epicardial continuity. Left ventricular cavity shape departed significantly from any simple geometric figure, there being, consistently, regions of both positive and negative curvature on the diaphragmatic aspect. The presence of trabeculae caused considerable variation in wall thickness. Striking variation was found in the arrangement of subepicardial muscle fibres. Most pronounced was the contrast between the longitudinal arrangement of fibres observed on the oblique margin and the circumferential arrangement of those on the acute. On the diaphragmatic surface of the left ventricle, fibres near the crux and apex ran circumferentially while those between ran obliquely; those on the diaphragmatic surface of the right ventricle also ran circumferentially. Deeper in the myocardium the arrangement was simpler. In the mid-wall of the left ventricle fibres were circumferential, best developed towards the base and in the upper part of the septum. Near the apex of the left ventricle and in the mid-wall of the right ventricle such fibres were sparse. The subendocardial region consisted of longitudinally directed fibres forming the trabeculae and papillary muscles, while fibres deep to and between the trabeculae coursed more obliquely. These findings were confirmed by histology. Models based on uniform myocardial fibre structure cannot explain wall movement in normal subjects, and are likely to have significant limitations if used to investigated left ventricular function in disease.

Dissection↗

PubMedDate not supplied

[Chagasic cardiomyopathy in Mexico].

Chronic Chagas disease, has been reported in Mexico, but changes in left ventricular function are not well known. We describe 25 patients with chronic trypanosomiasis with congestive cardiomyopathy. All of them lived in zones where the parasitosis is endemic and showed EKG abnormalities compatible with cardiomyopathy: A-V block in 8, RBBB in 9, LBBB in 7, RBBB + LAHB in 4, arrhythmias and ST-S abnormalities in 9 patients. All patients have at least one positive serological test for T Cruzi: indirect haemagglutination in 9, counterimmunoelectrophoresis in 9, complement fixation in 14 and passive agglutination of Latex sensitized beads in 4. The parasite was found by xenodiagnosis in 4 out of 5 cases. All cases had a normal coronary arteriography. The left ventriculography showed hypokinesia or akinesia of the apical, anterolateral and diaphragmatic segments in 8 patients and apical dyskinesia in 2. The ejection fraction varied from 22.3% to 51.6% with a mean of 39%. Chagas disease is a health problem in Mexico and the patients who are hospitalized present severe cardiac involvement.

Adult↗

PubMed2003

Task failure from inspiratory resistive loaded breathing: a role for inspiratory muscle fatigue?

The use of non-invasive resistive breathing to task failure to assess inspiratory muscle performance remains a matter of debate. CO2 retention rather than diaphragmatic fatigue was suggested to limit endurance during inspiratory resistive breathing. Cervical magnetic stimulation (CMS) allows discrimination between diaphragmatic and rib cage muscle fatigue. We tested a new protocol with respect to the extent and the partitioning of inspiratory muscle fatigue at task failure. Nine healthy subjects performed two runs of inspiratory resistive breathing at 67 (12)% of their maximal inspiratory mouth pressure, respiratory rate (fR), paced at 18 min(-1), with a 15-min pause between runs. Diaphragm and rib cage muscle contractility were assessed from CMS-induced esophageal (P(es,tw)), gastric (P(ga,tw)), and transdiaphragmatic (P(di,tw)) twitch pressures. Average endurance times of the first and second runs were similar [9.1 (6.7) and 8.4 (3.5) min]. P(di,tw) significantly decreased from 33.1 to 25.9 cmH2O in the first run, partially recovered (27.6 cmH2O), and decreased further in the second run (23.4 cmH2O). P(es,tw) also decreased significantly (-5.1 and -2.4 cmH2O), while P(ga,tw) did not change significantly (-2.0 and -1.9 cmH2O), indicating more pronounced rib cage rather than diaphragmatic fatigue. End-tidal partial pressure of CO2 ( PETCO2) rose from 37.2 to 44.0 and 45.3 mmHg, and arterial oxygen saturation (SaO2) decreased in both runs from 98% to 94%. Thus, task failure in mouth-pressure-targeted, inspiratory resistive breathing is associated with both diaphragmatic and rib cage muscle fatigue. Similar endurance times despite different degrees of muscle fatigue at the start of the runs indicate that other factors, e.g. increases in PETCO2, and/or decreases in SaO2, probably contributed to task-failure.

Adult↗

PubMed1981

Repair of large chest wall defects: experience with 23 patients.

The repair of large chest wall defects has been done on 23 patients who had 28 operations. Twenty-two patients had a neoplasm of the thoracic cage, while 1 had a large inflammatory mass. Nine patients had a partial lung and 3 a partial diaphragmatic resection done en bloc with the ribs. Seven resections were on the sternum. The repair was made either with a soft prosthesis (nylon mesh in 3 and Marlex mesh in 12 operations) or with a composite prosthesis of methyl methacrylate and metallic or Marlex mesh (13 operations). The association of methyl methacrylate and Marlex combines the solidity and the easy shaping of methyl methacrylate with the advantages of the mesh for an easy fixation and excellent incorporation. When the skin and the muscles are resected with the osteocartilaginous wall, an omentum flap is placed between the skin and the prosthesis to facilitate healing. There was one postoperative wound infection, which cleared with appropriate antibiotics. No prosthesis has extruded. The cosmetic and functional results are satisfactory. Repair of very large chest wall defects after resection can be done safely.

Adolescent↗