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PubMed2004

Anatomical investigation of the esophageal and aortic hiatuses: physiologic, clinical and surgical considerations.

Precise knowledge about the anatomical constitution of the diaphragmatic pillars is essential to understand the physiologic, clinical and surgical roles of the esophageal and aortic hiatuses. Because anatomical descriptions found in the literature are dubious, we have decided to investigate this subject. Anatomical dissections and histologic sections of the right and left diaphragmatic pillars (diaphragma crura) from 43 human bodies were analyzed, comprising both non-fixed and fixed specimens. We have described a classification of the diaphragmatic pillars and their muscular branches, forming two basic arrangements (patterns I and II) around the esophageal and aortic hiatuses. Such anatomical and functional relationships between the esophagus and its diaphragmatic hiatus help explain why, during normal inspiration, a hiatal enlargement is observed first but is followed, thereafter, during deep inspiration, by a hiatal narrowing exerted by the contraction of the diaphragmatic pillars. Our results also show that the aortic hiatus does not seem to constitute a rigid ventral tendinous arc around the aorta that could impose any considerable degree of vascular compression, as suggested by other investigators. The present study provides anatomical data useful for a better understanding of gastroesophageal reflux physiology, antireflux surgery and abdominal angina.

Aorta↗
PubMed1983

Effect of tension and timing of contraction on the blood flow of the diaphragm.

An open-chest animal model was developed to study the diaphragmatic blood flow (Qdi) during bilateral electrophrenic stimulation. Two patterns of stimulation were used, continuous and intermittent, and both patterns were held at various transdiaphragmatic pressures (Pdi). The contractions were nearly isometric and held at an initial length of supine functional residual capacity (FRC). Qdi was measured in six dogs by catheterizing a branch of the diaphragmatic vein and by counting the blood drops with an infrared cell. During continuous contractions Qdi increased as a function of Pdi up to 70 +/- 12 ml . 100 g-1 . min-1 at 20% Pdimax. At higher levels Qdi decreased progressively and approached zero at 75% of Pdimax. A postcontraction hyperemia occurred at Pdi values greater than 20% Pdimax and increased as a function of Pdi. During intermittent contractions Qdi was a unique function of the diaphragmatic tension-time index (TTdi), a product of Pdi times the duty cycle (contraction time/total cycle time). Qdi increased progressively up to a TTdi of 25% Pdimax and decreased above that point toward zero at TTdi of 80% Pdimax. The postcontraction hyperemia appeared at a TTdi of about 15% of Pdimax and increased as a function of TTdi. It is concluded that Qdi is limited beyond a TTdi of about 20% Pdimax, as indicated by the increase in postcontraction hyperamia, and that Qdi is a function of both Pdi and the timing of contraction.

Animals↗
PubMed1992

Changes in afferent and efferent phrenic activities with electrically induced diaphragmatic fatigue.

In anesthetized artificially ventilated cats, diaphragmatic fatigue was produced by direct muscle stimulation with trains of pulses for 30 min. Failure of contraction was assessed from decrease in the maximal relaxation rate of transdiaphragmatic pressure twitches. Motor activities (electromyogram and motor phrenic neurogram) were processed by fast-Fourier transform analysis, which provided the power spectrum density function (PSDF). The discharge frequency of diaphragmatic afferents was also measured. In control conditions (before fatigue), intra-arterial bolus injection of lactic acid enhanced tonically active diaphragmatic afferents, whereas it reduced the firing rate of afferent fibers activated in phase with diaphragmatic contraction or relaxation. The same sensory response pattern was observed with the development of diaphragmatic fatigue. Leftward shift in PSDFs of motor phrenic neurogram also occurred, but it preceded the failure of diaphragmatic contraction as well as the changes in the electromyogram's PSDF and afferent paths, which were closely associated with lengthening of both inspiratory and total breath durations. After section of the phrenic nerves, the motor phrenic response disappeared during the fatigue trial. This demonstrates the existence of complex reflex-induced changes in the ventilatory control during diaphragmatic fatigue. They seem to involve the participation of several types of phrenic afferents.

Action Potentials↗
PubMed1990

Effect of abdominal compression on maximum transdiaphragmatic pressure.

Transdiaphragmatic pressure (Pdi) is lower during maximum inspiratory effort with the diaphragm alone than when maximum inspiratory and expulsive efforts are combined. The increase in Pdi with expulsive effort has been attributed to increased neural activation of the diaphragm. Alternatively, the increase could be due to stretching of the contracted diaphragm. If this were so, Pdi measured during a combined maximum effort would overestimate the capacity of the diaphragm to generate inspiratory force. This study determined the likely contribution of stretching of the contracted diaphragm to estimates of maximum Pdi (Pdimax) obtained during combined inspiratory and expulsive effort. Three healthy trained subjects were studied standing. Diaphragmatic Mueller maneuvers were performed at functional residual capacity and sustained during subsequent abdominal compression by either abdominal muscle expulsive effort or externally applied pressure. Measurements were made of changes in abdominal (Pab) and pleural (Ppl) pressure, Pdi, rib cage and abdominal dimensions and respiratory electromyograms. Three reproducible performances of each maneuver from each subject were analyzed. When expulsive effort was added to maximum diaphragmatic inspiratory effort, Pdimax increased from 86 +/- 12 to 148 +/- 14 (SD) cmH2O within the 1st s and was 128 +/- 14 cmH2O 2 s later. When external compression was added to maximum diaphragmatic inspiratory effort, Pdimax increased from 87 +/- 16 to 171 +/- 19 cmH2O within the 1st s and was 152 +/- 16 cmH2O 2 s later.(ABSTRACT TRUNCATED AT 250 WORDS)

Abdomen↗
PubMed1984

Acute diaphragmatic shortening: in vitro mechanics and fatigue.

In acute hyperinflation, the occurrence of diaphragmatic shortening may alter the contractile characteristics and function of the diaphragm. The aim of this study was to investigate the effects of acute passive diaphragmatic shortening on in vitro mechanical properties and fatigability. Optimal diaphragmatic length (Lo) was defined as being that length at which peak twitch-tension occurred. Acute shortening (85% Lo, 70% Lo) altered the twitch characteristics. At shorter lengths, the time-to-peak tension and the half-relaxation time were significantly reduced (p less than 0.05). These alterations led to marked alterations in the shape of the force-frequency curve at shorter lengths and in the length-tension properties when assessed at different stimulation frequencies. When normalized with respect to maximal tension, a disproportionate decrease in the generated tension was observed at shorter lengths. Fatigability was assessed by repeatedly stimulating the diaphragmatic bundles and observing the drop in tension with respect to time. For a given fatigue regimen, i.e., same stimulation frequency, the shorter diaphragm (70% Lo) generated more absolute force at any given time period. When the initial tensions were matched at Lo and 70% Lo by increasing the stimulation frequency used to fatigue the shorter muscle, the acutely shortened diaphragm generated less absolute force following 60 s of the fatigue regimen. We conclude that alterations in the contractile characteristics of the diaphragm during acute passive shortening are such that a disproportionately greater excitability is required in order to reach a given submaximal tension as at Lo. This factor may partly account for increased diaphragmatic fatiguability in the acutely shortened state.

Animals↗
PubMed1991

Pediatric chest imaging.

Several new therapies have resulted in marked improvement in morbidity and mortality rates for neonates with respiratory distress syndrome and related disorders. These therapies include the use of exogenous surfactant to treat existing surfactant deficiency in babies with respiratory distress syndrome. Follow-up of patients previously treated with extracorporeal membrane oxygenation for diaphragmatic hernia has shown continued pulmonary function abnormalities despite this therapy. Follow-up studies have also shown significant neurologic abnormalities. New uses of ultrasonography include scanning of the larynx and airway for evaluating retropharyngeal and parapharyngeal infections and evaluating perithyroidal inflammation secondary to congenital fistulas in this region.

Child↗
PubMed1995

Nucleated erythrocyte count in newborn infants with left-sided congenital diaphragmatic hernia: relationship with the need for extracorporeal membrane oxygenation and survival.

Inadequate cardiac output in fetuses with left-sided congenital diaphragmatic hernia may cause chronic hypoxia and increased erythropoiesis. Postnatal nucleated erythrocyte counts were measured in 28 newborn infants with left-sided congenital diaphragmatic hernia who were eligible for extracorporeal membrane oxygenation (ECMO). Nucleated erythrocyte counts were lowest in infants who survived without ECMO, intermediate in survivors requiring ECMO, and highest in infants who died despite ECMO.

Analysis of Variance↗
PubMed2001

Inherited early onset severe axonal polyneuropathy with respiratory failure and autonomic involvement.

We report dizygotic twins who first presented at the age of 6 months with severe diaphragmatic weakness and marked abnormalities of autonomic function. A female sibling had earlier died from a disorder with similar clinical features. Both twins had a severe axonal polyneuropathy with generalized hypotonic limb weakness together with diaphragmatic paralysis resulting in respiratory failure. Associated features were tachycardia, increased sweating, elevated body temperature, and hypertension, suggesting autonomic dysfunction. Nerve conduction studies indicated an axonopathy affecting both motor and sensory nerve fibres. Sural nerve biopsy in one twin performed at the age of 7 months showed a reduced population of myelinated nerve fibres, particularly those of larger diameter, with no indication of hypomyelination, demyelination or axonal atrophy. Examples of axonal forms of hereditary motor and sensory neuropathy (HMSN) with onset in infancy are very rare and autonomic involvement associated with this condition has not so far been described.

Age of Onset↗
PubMed1992

Aging-associated deletions of human diaphragmatic mitochondrial DNA.

It is known that respiratory function deteriorates with age. Endogenous damage to DNA is thought to contribute to the aging process. The mitochondrial oxidative phosphorylation system, a bio-engine, consists of five complexes, and 13 subunits of those complexes are biosynthesized from information encoded in mitochondrial DNA. Mitochondrial DNA is shown to have a much higher mutation rate than nuclear DNA. We examined the diaphragms obtained at autopsy from 34 humans, 23 men and 11 women, ranging in age from 25 to 85 yr, for mitochondrial DNA deletions using the polymerase chain reaction method. Multiple mitochondrial DNA deletions were detected particularly among the elderly; the number of deletions in those over age 70 was significantly higher than in those under age 40. The occurrence of a 3.4-kbp deletion of mitochondrial DNA increased with age, i.e., 0% of those under age 30, 20.0% of those in their forties, 25.0% of those in their fifties, 28.6% of those in their sixties, 72.7% of those in their seventies, and in all of those over age 80. The mutation was based on the directly repeated sequence, 5'-TCACCCC-3', which exists in both the CO3 gene and the ND5 gene. Replication impairment occurred at that directly repeated sequence, which caused the elimination of a genome between the CO3 gene and the ND5 gene, and information for biosynthesis of four subunits in complex I (ND3, ND4L, ND4, and ND5), one in complex IV (CO3), and five transfer RNA genes was missing.(ABSTRACT TRUNCATED AT 250 WORDS)

Aging↗
PubMed1983

Postoperative pulmonary ventilation after cholecystectomy with and without peritoneal drain.

Postoperative lung function, chest X-ray and diaphragmatic movements were measured in 38 patients operated on with elective cholecystectomy with and without drain. 21 patients were drained and 17 were not drained. The results showed that there was a marked decrease of vital capacity (VC), peak expiratory flow (PEF) and diaphragmatic movements postoperatively in all patients. There was no statistically significant difference between patients with and without intraperitoneal drain. Postoperative chest X-ray changes were found in seven patients with drain and in two patients without drain. Patients with postoperative chest X-ray changes showed a much slower recovery of the measured variables. The difference in VC and PEF between patients with and without postoperative pulmonary complications was statistically significant from the third day postoperatively. It is postulated that pre- and postoperative monitoring of simple lung function tests can be helpful in early detection of postoperative pulmonary complications.

Adult↗
PubMed1987

Ventilatory predictors of pulmonary hypoplasia in congenital diaphragmatic hernia, confirmed by morphologic assessment.

We carried out a prospective study in 66 infants with congenital diaphragmatic hernia within the first 6 hours of life to determine whether outcome is related to the degree of underlying pulmonary hypoplasia, as predicted by preoperative PaCO2, when correlated with an index of ventilation (VI = mean airway pressure X respiratory rate) and confirmed by postmortem analysis of the lung. Those infants with PaCO2 greater than 40 mm Hg before surgery had a 77% mortality; when PaCO2 reduction could be achieved only with VI greater than 1000, the mortality was still greater than 50%. After repair, however, the ability to hyperventilate to PaCO2 less than 40 mm Hg proved to be an important determinant of survival; only one of 31 infants in this group died, whereas only two of 27 infants with PaCO2 greater than 40 mm Hg survived. In 16 infants with PaCO2 greater than 40 mm Hg despite hyperventilation, high-frequency oscillatory ventilation was started. This resulted in a rapid fall in PaCO2, but 14 of the 16 infants had only temporary improvement in oxygenation, and died. In five of the infants who died, alveolar number was assessed by postmortem morphometric analysis; there was a severe reduction to less than 10% of published normal neonatal values. Pulmonary vascular changes of increased muscularization were less remarkable than those observed in infants with persistent pulmonary hypertension. Our findings suggest that the degree of pulmonary hypoplasia (which would not be influenced by surgical repair), rather than the pulmonary vascular abnormality, mainly determines survival. Consideration could therefore be given to an initial nonsurgical approach to congenital diaphragmatic hernia, with the expectation that pulmonary function might improve and pulmonary vascular resistance decrease.

Hernia, Diaphragmatic↗
PubMed1993

Defecation syncope secondary to functional inferior vena caval obstruction during a Valsalva maneuver.

This report describes a case of defecation syncope secondary to functional inferior vena cava (IVC) obstruction. Preoperative hemodynamic assessment revealed a marked decrease in blood pressure and IVC obstruction when the patient performed a Valsalva maneuver. The intraoperative approach included continuous hemodynamic monitoring as well as transesophageal ultrasonography to assess IVC patency during surgical mobilization of the IVC. Functional obstruction of the IVC at the diaphragmatic hiatus was identified, and this obstruction was relieved with extensive mobilization of the IVC and right crural myotomy. This report describes an effective surgical approach to a rare functional disorder involving the IVC.

Adult↗
PubMed1978

Congenital diaphragmatic hernia associated with homolateral upper limb malformation: a study of possible pathogenesis in four cases.

Four cases of congenital diaphragmatic hernia associated with homolateral upper limb reduction deformities are presented and are analyzed in terms of their pathogenesis. Diaphragm and upper limb are supplied by adjacent segments of cervical neural crest, and the sensitive period for upper limb formation occurs during early neural crest development. The evidence supports the possibility of cervical neural crest injury as the underlying pathogenesis.

Arm↗
PubMed2005

Right-sided diaphragmatic hernia in infants after liver transplantation.

Liver transplantation is just as successful in infants as in older children, but more challenging. This relates to the low weight of the recipients and to their rapidly deteriorating clinical condition (malnutrition and end-stage liver disease) ( J Pediatr 1990;117:205-210; BMJ 1993;307:825-828; Ann Surg 1996;223:658-664; Transplantation 1997;64:242-248; J Pediatr Surg 1998;33:20-23). In addition, higher rates of diaphragmatic complications have been shown to significantly correlate with a younger age ( Transplantation 2002;73:228-232; Transpl Int 1998;11:281-283; Pediatr Transplant 2000;4:39-44), but diaphragmatic hernia has never been reported as a complication of liver transplantation. In this report, 2 patients who developed diaphragmatic hernia after liver transplantation are presented. The possible role of several contributing factors resulting in diaphragmatic hernia is discussed. These factors include (1) diaphragm thinness related to low weight and malnutrition, (2) direct trauma at operation (dissection and diathermy), (3) increased abdominal pressure after transplantation caused by the use of a slightly oversized liver graft, and (4) the medial positioning of the partial liver graft in the abdomen.

Body Weight↗
PubMed2005

Neonatal thoracoscopic repair of congenital diaphragmatic hernia: selection criteria for successful outcome.

BACKGROUND/PURPOSE: Complications of open conversion, hypercarbia, and intestinal injury have plagued minimally invasive approaches to congenital diaphragmatic hernia (CDH) repair in neonates. To safely begin using minimally invasive techniques for neonatal CDH repair, we formulated preoperative selection criteria and operative techniques that would enhance chances for successful thoracoscopic primary diaphragm repair and uncomplicated outcome. METHODS: During the period from January 2003 to October 2004, neonates were selected for thoracoscopic CDH repair using anatomic and physiologic criteria. Anatomically, all patients were required to have stomach in the abdomen by radiography. Physiologically, all patients were required to be on minimal ventilator support with preoperative ventilator peak inspiratory pressures in the low 20s mm Hg. No patient could have clinical evidence of pulmonary hypertension at the time of surgery. Thoracoscopic CDH repair was performed using 3 trocars (3 and 5 mm). The hernia contents were reduced into the abdomen using 5-mm Hg insufflation, and the diaphragms were repaired primarily using interrupted 3-0 Ethibond simple sutures (Ethicon, Inc, Piscataway, NJ). Posterolateral diaphragm stitches were passed around the posterolateral ribs and tied extracorporeally. RESULTS: Thirty neonates with CDH were admitted to Children's Hospital Boston and Vanderbilt Children's Hospital during the study period. Eight patients (27%) met selection criteria and 7 underwent thoracoscopic CDH repair. Primary diaphragmatic repair was successfully accomplished thoracoscopically in all neonates without perioperative complication. Preoperative anatomic criteria correlated accurately with intact esophageal hiatus and primary diaphragm repair. Physiologically, each patient tolerated intrathoracic insufflation and CDH repair without clinical pulmonary hypertension or blood pressure lability. Three patients had intraoperative respiratory acidosis that was reversed with ventilator changes. Operative times averaged 152 minutes and ranged from 212 to 106 minutes. Postoperative mechanical ventilation ranged from 0 to 7 days, and the length of hospitalization ranged from 5 to 32 days. Longest follow-up has been 17 months. One patient required reoperation for recurrent CDH at 10 months after repair, but there have been no other long-term complications. CONCLUSIONS: Neonatal thoracoscopic CDH repair is safe in selected patients who have good preoperative pulmonary function and anatomy amenable to primary diaphragmatic repair. A wider range of neonates may be acceptable for thoracoscopic CDH repair with increasing surgical experience.

Female↗
PubMed1984

Effects of theophylline on diaphragmatic strength and fatigue in patients with chronic obstructive pulmonary disease.

We studied the effects of theophylline on diaphragmatic strength and fatigue in 15 patients with severe chronic obstructive pulmonary disease. Diaphragmatic strength was assessed by measurement of the transdiaphragmatic pressure generated at functional residual capacity during a maximal inspiratory effort against closed airways. Diaphragmatic fatigue was induced by resistive loaded breathing. The electrical activity of the diaphragm was recorded with an esophageal electrode during the fatigue runs, and the high-low ratio of the electrical signal was analyzed to assess diaphragmatic fatigue. Studies were performed before and after 7 and 30 days of theophylline administration (mean plasma level, 13 +/- 2 mg per liter). A control group received a placebo instead of theophylline. Theophylline increased maximal transdiaphragmatic pressure by 16 per cent after 7 days of administration (P less than 0.01), and this increase persisted after 30 days. No significant change in maximal transdiaphragmatic pressure was observed in the group given the placebo. Theophylline also suppressed diaphragmatic fatigue in all patients who received it. We conclude that theophylline has a potent and long-lasting effect on diaphragmatic strength and fatigue in patients with fixed airway obstruction.

Diaphragm↗
PubMed1993

Early assessment of diaphragmatic dysfunction in children in the ITU: chest radiology and phrenic nerve stimulation.

Diaphragmatic dysfunction is a common postoperative complication of cardiac surgery in children, with important effects on respiratory morbidity. Its early diagnosis, followed by prompt surgical intervention, has been shown to reduce morbidity. However, the commonest method of diagnosis, based on hemi-diaphragmatic elevation on the chest radiograph, may be less accurate than direct techniques for assessing phrenic nerve function. We have compared electrophysiological and radiological diagnoses of diaphragmatic abnormality in 100 children (aged 3 days to 17.5 yrs) undergoing cardiac surgery, looking at respiratory morbidity as assessed by the duration of ventilation, the time spent on the cardiac intensive care unit (CICU), and the requirement for reintubation. Despite showing good reproducibility, radiological diagnosis was neither sensitive nor specific in identifying patients with electrophysiological phrenic nerve damage. Analysis of the measures of outcome supported the electrophysiological technique. Patients with electrophysiological evidence of damage had a longer duration of ventilation, spent longer on the CICU, and had a greater incidence of reintubation than either radiologically abnormal or "normal" patients. Chest X-rays are not a good method for diagnosing phrenic nerve damage in the early postoperative period in children. If early diagnosis is needed, then direct assessment of phrenic nerve function, such as the measurement of phrenic latency, may be a better technique.

Adolescent↗