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At least 631 records · Page 35Linked to original sources
PubMed1984

Respiratory muscle length measured by sonomicrometry.

The use of sonomicrometry to study the mechanical properties of the diaphragm in vivo is presented. This method consists of the implantation of piezoelectric transducers between muscle fibers to measure the fibers' changes in length. Ultrasonic bursts are produced by one transducer upon electrical excitation and sensed by a second transducer placed 1-2 cm away. The time elapsed between the generation of the ultrasound burst and its detection is used to calculate the intertransducer distance. Excitation and sampling are done at 1.5 kHz and the output is a DC signal proportional to the length change between the transducers. Neither irreversible injury to the diaphragm nor regional differences within an anatomical part or segment were noted. Measurements were stable within the physiological range of temperature. We measured costal and crural length and velocity of contraction in anesthetized dogs during spontaneous breathing, occluded inspirations, passive lung inflation, and supramaximal phrenic nerve stimulation. We found that shortening during spontaneous breathing was 11 and 6% for crural and costal, respectively. The crural leads the costal in velocity of shortening. Supramaximal stimulation results in a velocity of shortening of 5 resting lengths X s-1. During an occluded inspiration crural shortens as much as in the nonoccluded breath, whereas costal shortens less. During passive lung inflation there is a nearly linear relationship between lung volume and diaphragm length; however, the relationships of chest wall dimensions with diaphragm length are nonlinear and cannot be described by any simple function. Some of the implications of these data on the present understanding of diaphragmatic mechanics are discussed.

Animals↗
PubMed1995

[Electrostimulation of the diaphragmatic muscle in bronchial asthma patients].

A study was made of the effect of transcutaneous diaphragmatic electrostimulation (2 mA, 0.3 ms, 20-30 V) on the external respiratory function in 12 asthmatic patients with respiratory insufficiency. The course comprised 7 daily sessions for 20 min. The improvement in respiratory function parameters was observed in the majority of the patients. The effect of electrostimulation was related to the quantity of the procedures.

Adult↗
PubMed1991

[Bilateral diaphragmatic paralysis, the cause of acute insufficiency in chronic obstructive bronchopathy. The value of nasal mechanical ventilation].

A 57 year old man with chronic bronchitis sought a consultation for dyspnoea at rest associated with an absolute inability to lie flat. Examination revealed paradoxical respiration and respiratory function testing revealed a mixed ventilation disturbance, which was predominantly obstructive and was aggravated in the dorsal decubitus position. Radiology revealed bilateral diaphragmatic paralysis, which was confirmed on measurement of transdiaphragmatic pressure. The patient benefited from assisted ventilation by the nasal route with an excellent result in both the short and the medium term. Investigation into the cause was negative, in particular there was no evidence of any neuromuscular abnormality. This case recalls the role of the diaphragm in acute respiratory failure and shows the value of mechanical ventilation by the nasal route in the treatment of certain types of diaphragmatic paralysis.

Bronchitis↗
PubMed2002

Effects of abdominoplasty on respiratory functions: a prospective study.

The short-term and the long-term effects of abdominoplasty on the respiratory function of healthy adults are not known because of a lack of studies on this subject. Theoretically one might suggest that abdominoplasty can cause respiratory decompensation resulting from musculofascial plication, which reduces the respiratory reserve by decreasing intra-abdominal volume and diaphragmatic excursion. This prospective study was performed to evaluate the short-term effects of abdominoplasty on the pulmonary function of 14 consecutive otherwise healthy subjects. Calculation of the body mass index, measurement of the waist circumference, and the distance from xiphoid to umbilicus, and spirometry were performed for each subject preoperatively, and they were repeated at 10 and 30 days after the operation. The mean values of body mass index (p < 0.001), waist circumference (p < 0.05), and the distance from xiphoid to umbilicus (p < 0.001) were all decreased significantly by postoperative day 10. Comparison of the spirometric measurements showed a significant improvement in the mean forced vital capacity (p < 0.01) on day 30 postoperatively, whereas the mean forced expiratory volume in first second did not change throughout the study period. The authors conclude that abdominoplasty could improve pulmonary function in healthy subjects by increasing the forced vital capacity.

Abdomen↗
PubMed2003

Can diaphragmatic contractility be assessed by airway twitch pressure in mechanically ventilated patients?

BACKGROUND: In critically ill patients inspiratory muscle function may be assessed by measurements of maximal inspiratory airway pressure and the response of twitch transdiaphragmatic pressure (Pdi tw) to bilateral phrenic nerve stimulation. The first is limited by its total dependence on patient cooperation. Although the second approach is independent of patient volition, it is impractical because it requires oesophageal and gastric balloons. Because airway pressure is easily and non-invasively recorded in patients with artificial airways, we hypothesised that twitch airway pressure (Paw tw) reliably predicts Pdi tw and twitch oesophageal pressure (Poes tw) in mechanically ventilated patients. METHODS: Thirteen mechanically ventilated patients recovering from an episode of acute respiratory failure received phrenic nerve stimulation at end exhalation. The rapid occlusion technique was used to record respiratory system mechanics. RESULTS: Stimulations were well tolerated. Mean (SE) Paw tw at end exhalation was -8.2 (1.2) cm H(2)O and Poes tw and Pdi tw were -7.3 (1.1) and 10.4 (1.8) cm H(2)O, respectively. Stimulations produced a good correlation between Paw tw and Pdi tw (p<0.001), although the limits of agreement were wide. The results were similar for Poes tw. No relationship was found between the Paw tw/Poes tw ratio and respiratory system compliance or airway resistance. Paw tw reproducibility was excellent (mean coefficient of variation 6%, range 3-9%). CONCLUSIONS: Despite a good correlation between Paw tw and Poes tw, Paw tw did not reliably predict Poes tw or Pdi tw in mechanically ventilated patients. Nevertheless, the excellent reproducibility of Paw tw suggests that it may be a useful means of monitoring inspiratory muscle contractility in the routine care of mechanically ventilated patients.

Adult↗
PubMed2006

Small lungs and suspect smooth muscle: congenital diaphragmatic hernia and the smooth muscle hypothesis.

Lung hypoplasia and congenital diaphragmatic hernia (CDH) represent an unsolved clinical and scientific problem. Early lung morphogenesis is coupled to development and function of pulmonary smooth muscle. Activity of the latter is abnormal from the earliest stages of hypoplastic lung development and before supervening CDH. A "smooth muscle hypothesis" is advanced to help explain embryonic lung malformations, fetal failure of lung growth, and postnatal susceptibility to barotrauma, airway hyperreactivity, and pulmonary hypertension in CDH. Exploring the interaction of smooth muscle function and airway pressures may help optimise tracheal occlusion and provide support for both an adequately powered trial of glucocorticoids and also for experimental "preventilation" strategies in fetal CDH.

Fetal Diseases↗
PubMed1996

Maximal oxygen consumption and stress performance in children operated on for congenital diaphragmatic hernia.

The long-term follow-up of patients operated on for congenital diaphragmatic hernia (CDH) at birth has been extensively evaluated, both clinically and with respect to respiratory function. However, little is known about the sports practice and stress performance of these subjects. Fifteen of 107 patients operated on for CDH underwent exercise stress testing with a stepwise increase in workload. A questionnaire was provided, which requested information on sports practice and lifestyle. Maximal oxygen consumption [Vo2 max] was measured along with dynamic lung volumes. Clinical examination included a whole-body assessment (height, weight, skinfolds) and vital parameters (heart rate and blood pressure). Fifteen healthy children who practiced regular physical activity (2 to 4 hours/week) served as controls. All the CDH patients experienced a good lifestyle, but only 8 of them were participating in sports. Exercise duration and Vo2 max were significantly lower for the CDH patients, and were lowest for the sedentary patients. Therefore, the reduced Vo2 max of these otherwise healthy children most likely represents a lower degree of physical fitness rather than decreased respiratory function. Fitness is an expression of well-being; thus, there is evidence that these patients could safely participate in competitive motor activities.

Adolescent↗
PubMed1999

The diaphragmatic compound muscle action potentials (DCMAPs) at different lung volumes--a prospective electrophysiological study of the respiratory system.

Phrenic nerve conduction study and measurements of static lung volumes such as functional residual capacity (FRC), total lung capacity (TLC) and residual volumes (RV) using body plethysmography were carried out in 31 normal healthy male subjects (31 +/- 8 years). The objective was to correlate changes in latency, amplitude, duration and area of diaphragmatic compound muscle action potential (DCMAPs) with lung volumes and changes in them with changes in postures. The mean phrenic nerve latency did not show any significant change with lung volumes or postures, but the latency and height of the subject had a significant correlationship (r = 0.68). The peak to peak amplitude of DCMAP showed a significant relationship with the quantitative lung volumes (r = 0.65). The amplitude was significantly higher and duration reduced (p < 0.001) at TLC as compared with those at measured FRC and RV in both sitting and supine postures. The area under the curve did not change significantly. Similarly, amplitudes and latency did not show any significant relation with other anthropometric parameters. The study evaluates a new quantitative relationship between DCMAPs amplitude and lung volumes. This may be carefully used along with other clinical parameters in critically ill patients for an early weaning from ventilator. Posture exerts minimal influence on DCMAPs amplitude; since DCMAPs amplitudes depends on the position of the diaphragm which in turn depends on dipolic potential, its electromagnetic fields and its moving angle subtends at the recording electrode, one can confidently use it to predict lung volume in respiratory failure due to neuromuscular diseases where subjective lung function assessment is impossible. However, a further study is in process in the critical care unit to confirm its utility.

Action Potentials↗
PubMed2002

Lysyl oxidase is required for vascular and diaphragmatic development in mice.

Lysyl oxidase (LOX) is an enzyme responsible for the cross-linking of collagen and elastin both in vitro and in vivo. The unique functions of the individual members of this multigene family have been difficult to ascertain because of highly conserved catalytic domains and overlapping tissue expression patterns. To address this problem of functional and structural redundancy and to determine the role of LOX in the development of tissue integrity, Lox gene expression was deleted by targeted mutagenesis in mice. Lox-targeted mice (LOX(-/-)) died soon after parturition, exhibiting cardiovascular instability with ruptured arterial aneurysms and diaphragmatic rupture. Microscopic analysis of the aorta demonstrated fragmented elastic fiber architecture in homozygous mutant null mice. LOX activity, as assessed by desmosine (elastin cross-link) analysis, was reduced by approximately 60% in the aorta and lungs of homozygous mutant animals compared with wild type mice. Immature collagen cross-links were decreased but to a lesser degree than elastin cross-links in LOX(-/-) mice. Thus, lysyl oxidase appears critical during embryogenesis for structural stability of the aorta and diaphragm and connective tissue development.

Alleles↗
PubMed2001

Thoracoscopic treatment for delayed presentation of congenital diaphragmatic hernia in the infant. A report of three cases.

BACKGROUND: Delayed presentations of congenital hernia occurring outside of the neonatal period have been reported for all ages. Classically, repair of the hernia defect involves a transverse subcostal laparotomy in the pediatric age group and usually a thoracotomy in the adult. The first report describing a laparoscopic repair of a congenital diaphragmatic hernia in a 6-month-old infant was published in 1995. During the past 25 years, 17 patients with delayed presentation of congenital diaphragmatic hernias have been managed by our pediatric surgery team. The last three patients underwent surgery thoracoscopically. PATIENTS AND METHODS: This study involved two boys (ages, 8.3 and 19 months, respectively) and one girl (age, 9 months) weighing 8 to 13 kg. All three infants underwent surgery using a thoracoscopic approach with general anesthesia. A thoracic epidural catheter was placed systematically for postoperative analgesia during the first 24 hours. Reduction of the hernia contents using one optical trocar and two operating trocars was difficult in the case without any hernia sac. In the cases with a hernia sac, reduction was easily and quickly obtained with a pleural insufflation of carbon dioxide (~8 mmHg). The hernia defect was repaired using interrupted sutures of 2/0 Ethibond. For two of the three patients, this repair was reinforced with staples in the one case and a nonresorbable mesh in the other case. RESULTS: The mean operative time was 78 min. The chest tube was removed on the first or second postoperative day and the patients were discharged on the fourth or fifth postoperative day. At the 19-month follow-up assessment in one case, the chest x-ray was perfectly normal and diaphragmatic motion also was confirmed to be normal by ultrasonography. CONCLUSIONS: The thoracoscopic approach for the repair of delayed-presentation congenital diaphragmatic hernia is feasible. Our results demonstrate the safety and efficiency of this surgery, as well as a remarkable functional and cosmetic result and a very quick recovery.

Female↗
PubMedDate not supplied

[The results of the Ravitch-Sutherland technic for surgical correction in pectus excavatum].

The aim of our study was to assess the functional and cosmetic results after performing a modified Ravitch-Sutherland procedure in children presenting with excavatum. A series of 31 children with ages ranging between 5 and 16 years, presenting with pectus excavatum, were operated between 1986-1996 in our service. In 5 cases surgical treatment was required by the presence of respiratory and/or cardiac functional impairment due to the malformation. In the other 23 cases operation was performed mainly for cosmetic reasons. In all cases a modified Ravitch-Sutherland procedure was performed. Modification consisted in renouncing at the plicature of the perichondra and in associating a diaphragmatic elongation and Bedouelle laparoplasty in all cases. Longitudinal sternotomy was performed in 2 cases with severely impaired ventilatory capacity. Functional and cosmetic results were good in all cases. In 2 cases, in which recurrence of the condition was observed, a second identical procedure was performed, with a good result. The interval between the operation and the moment of long-term evaluation ranged between 3 months and 11 years. We conclude that the modified Ravitch-Sutherland procedure represents an effective method for the treatment of pectus excavatum cases, offering good functional and cosmetic long-term results.

Child↗
PubMedDate not supplied

[The results of the Ravitch-Sutherland technic for surgical correction in pectus excavatum].

The aim of our study was to asses the functional and cosmetic results after performing a modified Ravitch-Sutherland procedure in children presenting with pectus excavatum. A series of 31 children with ages ranging between 5 and 16 years, presenting with pectus excavatum, were operated between 1986-1996 in our service. In 5 cases surgical treatment was required by the presence of respiratory and/or cardiac functional impairment due to the malformation. In the other 23 cases operation was performed mainly for cosmetic reasons. In all cases a modified Ravitch-Sutherland procedure was performed. Modifications consisted in renouncing at the plication of the perichondrium and in associating a diaphragmatic elongation and Bedouelle laparoplasty in all cases. Longitudinal sternotomy was performed in 2 cases with severely impaired ventilatory capacity. Functional and cosmetic results were good in all cases. In 2 cases, in which recurrence of the condition was observed, a second identical procedure was performed, with a good result. The interval between the operation and the moment of long-term evaluation ranged between 3 months and 11 years. We conclude that the modified Ravitch-Sutherland procedure represents an effective method for the treatment of pectus excavatum cases, offering good functional and cosmetic long-term results.

Child↗
PubMedDate not supplied

Obesity as a possible cause of respiratory failure in bilateral diaphragmatic paralysis. Case report.

An obese woman with respiratory failure and bilateral diaphragmatic paralysis, was studied in order to investigate the effects of weight loss on respiratory function during wakefulness and sleep. The patient was studied on 5 different occasions during which diurnal blood gas analysis, spirometry, CO2 rebreathing test, nitrogen wash-out test and a nocturnal polysomnographic study were performed. The follow-up period lasted 9 months, during which the patient progressively lost 19 kg. Progressive improvement in awake blood gas tensions (PaO2 + 21 mmHg, PaCO2 - 16 mmHg) as well as in nocturnal oxyhemoglobin saturation and transcutaneous PCO2 were observed; at the same time only minor changes in responsiveness to CO2 and in lung volumes were found. Conversely alveolar efficiency for CO2, obtained with the nitrogen wash-out test, in the supine posture increased from 81.7 to 90.5%, indicating an improvement in ventilation/perfusion ratio as a possible determinant of blood gas tension improvement during wakefulness and, as a consequence, also during sleep. We conclude that obesity is one possible cause of the occurrence of respiratory failure in bilateral diaphragmatic paralysis.

Adult↗
PubMed1989

Cardiopulmonary effects of the volume recruitment manoeuvre in infant swine.

The volume recruitment manoeuvre is a non-invasive technique used to measure respiratory mechanics in infants. Because airway pressure increases during this manoeuvre, lung volume, compliance and cardiac output may change. In order to assess possible changes in cardiopulmonary function caused by the volume recruitment manoeuvre, we applied this technique to seven intubated infant swine breathing spontaneously during anaesthesia with halothane and N2O. Tidal volume (VT), respiratory frequency, arterial blood gases, cardiac output (CO) and total respiratory compliance were measured before and after the manoeuvre. In three swine functional residual capacity (FRC) was measured by helium dilution before the manoeuvre, and in four swine diaphragmatic EMG was recorded continuously. Finally, all swine were paralysed during volume recruitment to assess the contribution of the respiratory muscles to post-manoeuvre respiratory mechanics. VT and f increased immediately after the manoeuvre but there were no significant changes in PaCO2, or alveolar to arterial oxygen gradient. There was a small but statistically significant decrease in CO. Compliance increased by 17.8 +/- 3.6 per cent and FRC increased by a mean of 41.1 ml (or 51.9 per cent increase above the baseline FRC). The increase in FRC could not be explained by active mechanisms since the diaphragmatic EMG showed no post-inspiratory activity and neuromuscular paralysis did not decrease FRC. We conclude that the volume recruitment manoeuvre increases FRC and compliance by recruiting collapsed alveoli, and this effect must be taken into consideration when applying this test to infants.

Anesthesia, Inhalation↗
PubMed1991

Role of phrenic nerve afferents in the control of breathing.

A long-held belief is that respiratory-related reflexes mediated by afferents in the diaphragm are weak or absent. However, recent data suggest that diaphragmatic afferents are capable of altering ventilatory motor drive as well as influencing perception of added inspiratory loads in humans. This review describes the sensory elements of the diaphragm, their central projections, and their functional significance in the control of respiratory muscle activation. The reflexes elicited by electrical stimulation of phrenic nerve afferents and the contribution of diaphragmatic afferents in respiratory load compensation and perception are considered. There is growing evidence that phrenic nerve afferents are activated under a variety of conditions. However, the significance of this input to the central nervous system is yet to be discerned.

Afferent Pathways↗