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PubMedDate not supplied

The effect of continuous interscalene brachial plexus block with 0.125% bupivacaine plus fentanyl on diaphragmatic motility and ventilatory function.

BACKGROUND AND OBJECTIVES: Continuous interscalene brachial plexus block with 0.25% bupivacaine decreases diaphragmatic motility and ventilatory function. The author studied the effects of 0.125% bupivacaine with and without fentanyl. METHODS: Forty patients who were to undergo shoulder surgery were given an interscalene brachial plexus block using 20-28 ml 0.75% bupivacaine plus epinephrine. In random order, 10 patients then had a 24-hour continuous block with 0.125% bupivacaine (BUPI) (5-9 ml/h). Nine patients had an additional s.c. infusion of fentanyl (F-SC) (15-27 micrograms/h) and 10 the same dose of fentanyl with the bupivacaine infusion (F-PLX). Ten patients had a single block (PLX) for minor surgery. Spirometry, double-exposure chest radiography, pulse oximetric hemoglobin saturation and maximal airway pressures were measured. RESULTS: Postoperatively, BUPI patients were given, on average, 1.2, F-SC patients 0.7, and F-PLX patients 0.4 doses of oxycodone in 24 hours (not significant). Average ipsilateral diaphragmatic motility was reduced to 8% in F-PLX group (p < 0.01) and to 19-30% in the other groups (p < 0.05). At 24 hours, average motility in BUPI, F-SC, F-PLX and PLX groups was 54, 48, 31 and 91%, respectively. In all groups FVC, FEV1 and PEF were reduced by 20-40% at 3 hours (p < 0.001). At 8 and 24 hours, FVC and FEV1 were in F-SC and F-PLX groups significantly lower (p < 0.05) than in PLX group. CONCLUSIONS: Use of 0.125% bupivacaine for continuous interscalene block did not prevent a deterioration of diaphragmatic motility and ventilatory function. Co-infusion of fentanyl did not significantly potentiate the block.

Adult↗

PubMed1986

Effect of theophylline on diaphragmatic and other skeletal muscle function.

Methylxanthines and particularly caffeine are known to increase skeletal muscle contractility. Recently, it has been shown that theophylline improves diaphragmatic contractility of the respiratory muscles both in isolated muscle preparations and in animals and normal human beings. Furthermore, it has been demonstrated that theophylline reverses diaphragmatic fatigue and prevents fatigue of the diaphragm when it is given prophylactically. Finally, recent evidence indicates that theophylline improves diaphragmatic function in patients with chronic obstructive pulmonary disease, all of whom retained CO2 (PaCO2 43 +/- 3 mm Hg) and had hypoxia (PaO2 57 +/- 8 mm Hg). Patients both improved transdiaphragmatic pressure and were less susceptible to fatigue. These data strongly suggest that theophylline, which increases respiratory muscle strength and delays the onset of diaphragmatic fatigue, could be a very useful agent in the treatment of patients with chronic airway obstruction.

Animals↗

PubMed2004

Lung function in lambs with diaphragmatic hernia after reversible fetal tracheal occlusion.

BACKGROUND/PURPOSE: Short-duration resuscitation (< or =4 hours) of lambs with diaphragmatic hernia treated in utero with tracheal occlusion have shown improved lung function compared with untreated diaphragmatic hernia. This may be a transient phenomenon in the treated diaphragmatic hernia lambs because of surfactant deficiency. Our objective was to analyze the effect of fetal tracheal occlusion with or without release of the occlusion 1 week before delivery on pulmonary function during a longer period of resuscitation (8 hours) in the diaphragmatic hernia lamb model. METHODS: Four groups were compared: diaphragmatic hernia (n = 5), diaphragmatic hernia and tracheal occlusion until delivery (n = 5), diaphragmatic hernia and tracheal occlusion with release of the occlusion 1 week before delivery (n = 5), and normal controls (n = 4). RESULTS: Despite persistently decreased surfactant levels, diaphragmatic hernia lambs treated with tracheal occlusion had normal-sized lungs with marked improvement in lung function and gas exchange over 8 hours when compared with untreated lambs with diaphragmatic hernia. Release of the tracheal occlusion 1 week before delivery added no benefit. CONCLUSIONS: It appears that surfactant-independent mechanisms such as pulmonary growth and structural changes are of foremost importance in relating to improved compliance, oxygenation, and ventilation of diaphragmatic hernia lambs treated with tracheal occlusion.

Animals↗

PubMed1989

Effects of isoflurane on contractile properties of diaphragm.

Isoflurane has been shown to depress skeletal muscle force in vitro, but data are not available regarding the effects of isoflurane on diaphragmatic muscle function in vivo. To answer this question, 15 rats anesthetized with pentobarbital and mechanically ventilated were studied. They were divided into three groups of five animals each, according to the administered concentration of isoflurane. Diaphragmatic function was assessed by measuring the transdiaphragmatic pressure (Pdi) generated during bilateral supramaximal phrenic nerve stimulation at 0.5 Hz, 20 Hz, 50 Hz, and 100 Hz under quasi-isometric conditions. After a control measurement (C), isoflurane was administered at a constant concentration (0.5, 1, or 1.5 MAC) and Pdi measurements were repeated after 30 min of isoflurane exposure (T1) and 30 min after discontinuing isoflurane (T2). In the group breathing 1.5 MAC isoflurane, the time constant of diaphragmatic relaxation (tau) and integrated electrical activity of the diaphragm (Edi) were also assessed. The Pdi amplitude generated by single twitch (0.5 Hz) was unchanged at the three isoflurane concentrations. A significant increase in Pdi at 20 Hz was observed at T1, which returned to control after 30 min recovery (T2). No change in Pdi during 50 Hz stimulation was noted during 0.5 and 1 MAC isoflurane exposure, whereas it was reduced at T1 during 1.5 MAC. For 100 Hz stimulation, a significant decrease in Pdi was noted for all groups at T1, which returned toward control values at T2. Edi was markedly reduced for 50 and 100 Hz stimulation, but this reduction was also transient, since Edi returned toward control values at T2.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed2000

Diaphragmatic dysfunction secondary to experimental lower torso ischaemia-reperfusion injury is attenuated by thermal preconditioning.

BACKGROUND: Preconditioning describes the process whereby tissue exposure to a subcritical stress confers protection from subsequent injuries. This study assessed diaphragmatic muscle function after lower torso ischaemia-reperfusion (IR) and the role of thermal preconditioning in attenuation of this injury. METHODS: Sprague-Dawley rats were randomized into three groups (24 per group): a control group, an IR group that had aortic cross-clamping for 1 h followed by reperfusion, and a third group that received thermal preconditioning 18 h before IR. Diaphragmatic function was assessed at 24 h, 48 h and 7 days. RESULTS: IR resulted in significant diaphragmatic twitch and tetanic dysfunction compared with control muscle. Thermal preconditioning significantly attenuated this injury (P < 0.05). Mean(s.e.m.) muscle twitch and tetanic forces in the IR group were 204.9(17.2) and 282.7(19.2) g respectively at 24 h. Corresponding twitch and tetanic forces in preconditioned muscle were 270.4(25.1) and 552.0(35.2) g. CONCLUSION: This study demonstrated that systemic IR injury produced a respiratory muscle mechanical dysfunction that was attenuated by thermal preconditioning, at 24 h, 48 h and 7 days. Preconditioning may have a role in clinical practice, particularly before elective surgery.

Animals↗

PubMed2005

Interscalene brachial plexus block with bupivacaine and ropivacaine in patients with chronic renal failure: diaphragmatic excursion and pulmonary function changes.

In this randomized, double-blind study, we compared the anesthetic characteristics and pulmonary function changes of 0.33% bupivacaine and 0.33% ropivacaine used for interscalene brachial plexus (IBP) anesthesia in patients with chronic renal failure. Forty-two patients undergoing IBP anesthesia for creation of arteriovenous fistulas were randomly allocated to receive either 30 mL of 0.33% bupivacaine (Group B) or 0.33% ropivacaine (Group R). Block onset time, diaphragmatic excursion (ultrasonographic evaluation), and free plasma concentrations of bupivacaine and ropivacaine were evaluated. Negative motion or immobility of the ipsilateral hemidiaphragm and a decrease of >10 mm in positive motion were defined as diaphragmatic paresis. The pulmonary function variables were measured by bedside spirometry equipment. Seven patients needed supplemental local anesthetic, one with total spinal block; these patients were excluded from the study. The success rate was 80.9%. Block quality was similar in the two groups. Ipsilateral hemidiaphragmatic excursion was decreased in both groups compared with baseline values (P < 0.05). Diaphragmatic paresis was identified in 10 of 16 patients and 8 of 18 patients in Groups B and R, respectively (P > 0.05). Pulmonary function significantly decreased from baseline in both groups (forced vital capacity (FVC) 30%, forced expiratory volume at 1 second (FEV(1)) 32%, and peak expiratory flow (PEF) 31% in Group B and FVC 17%, FEV(1) 17%, and PEF 5% in Group R) (P < 0.001). The decreases in Group B were larger than those in Group R (P < 0.05). Three patients in Group B and one in Group R had mild respiratory problems (P > 0.05). Concentrations of bupivacaine and ropivacaine were below toxic levels rather than "normal range." We conclude that pulmonary function decreased more after IBP with 0.33% bupivacaine than with 0.33% ropivacaine.

Adolescent↗

PubMedDate not supplied

Diaphragmatic excursion and respiratory function after the modified Raj technique of the infraclavicular plexus block.

BACKGROUND: The effects of the infraclavicular plexus block using the modified Raj approach on diaphragm and respiratory function have not been investigated. METHODS: After obtaining approval of the local ethics committee and written informed consent, 20 patients, scheduled for surgery of the forearm, wrist, or hand were prospectively included. Infraclavicular block was performed using the modified Raj technique with 40 to 50 mL ropivacaine 0.5%. Forced diaphragmatic excursion (DE), vital capacity (VC), first-second forced expiratory volume (FEV(1)), and peak expiratory flow rate (PEFR) were assessed the day before surgery and 30 and 360 minutes after blocks, respectively. RESULTS: There was no significant difference between pre- and postblock values, neither for DE (5.6 +/- 1.0 cm before the block, 5.2 +/- 1.4 cm 30 minutes after the block, and 5.7 +/- 1.4 cm 360 minutes after the block) nor for VC (3.2 +/- 0.8 L before the block, 3.1 +/- 0.9 L 30 minutes after the block, and 3.0 +/- 0.9 L 360 minutes after the block), FEV(1) (2.8 +/- 0.9 L before the block, 2.8 +/- 0.9 L 30 minutes after the block, and 2.7 +/- 0.9 L 360 minutes after the block), or PEFR (378 +/- 116 L/min before the block, 355 +/- 110 L/min 30 minutes after the block, and 364 +/- 116 L/min 360 minutes after the block). CONCLUSION: Infraclavicular block using the modified Raj technique did not interfere with diaphragmatic excursion or respiratory function.

Adult↗

PubMed2000

Short-term tracheal occlusion in fetal lambs with diaphragmatic hernia improves lung function, even in the absence of lung growth.

BACKGROUND/PURPOSE: Prolonged tracheal occlusion (TO) accelerates lung growth but impairs surfactant production. Short-term TO results in less lung growth but preserves type II cell function. The authors studied the effects of short-term TO on lung physiology in diaphragmatic hernia. METHODS: Diaphragmatic hernia was created in 9 fetal lambs at 90 to 95 days. Five were left uncorrected (CDH), 4 underwent 2-week TO (108 to 122 days; CDH + TO). Five unoperated lambs served as controls. Near-term (136 days) fetuses were ventilated for 90 to 150 minutes. Pulmonary arterial pressure, postductal blood gases, quasistatic compliance, total lung capacity (TLC), and lung weight to body weight (LW/BW) were measured. RESULTS: There was an overall survival rate of 89% at full term. Short-term occlusion did not induce lung growth (TLC and LW/BW, 6.07 +/- 2.92 mL/kg and 0.022 +/- 0.008 in CDH, 4.86 mL/kg and 0.019 +/- 0.005 in CDH + TO, 10.81 +/- 3.55 mL/kg and 0.036 +/- 0.006 in controls, respectively). However, pulmonary hypertension in CDH (47.4 +/- 12.32/35.8 +/- 12.19 torr) was corrected by short-term occlusion (20.2 +/- 4.0/16.0 +/- 4.8 torr in CDH + TO, P< .05, single-factor analysis of variance [ANOVA]; similar to control). Best pO2 and pCO2 improved after occlusion (CDH, 48.6 +/- 6.7 torr and 107.1 +/- 34.3 torr, respectively; CDH + TO, 101.5 +/- 16.3 torr and 81.9 +/- 2.4 torr; control, 291.4 +/- 4.7 torr and 37.7 +/- 17.3), as did oxygenation index (P < .05, CDH vCDH + TO; CDH, 97.2 +/- 23.0; CDH + TO, 28.7 +/- 3.1; control, 5.6 +/- 0.6). CONCLUSIONS: Short-term TO corrects pulmonary hypertension and improves gas exchange in fetal lambs with diaphragmatic hernia despite failure to produce accelerated lung growth. Inducing lung maturation and correcting the physiological derangement in diaphragmatic hernia may be more important than achieving lung growth alone.

Analysis of Variance↗

PubMed1984

Isolated bilateral diaphragmatic paresis with interstitial lung disease. An unusual presentation of dermatomyositis.

A case of dermatomyositis (DM) with only one abnormal muscle function, bilateral diaphragmatic paresis, is reported. The coexistence of interstitial lung disease allowed us to sample the diaphragm during an open lung biopsy. Characteristic features of myositis were found. Lung volumes, compliance, maximal inspiratory pressure, and transdiaphragmatic pressure gradient (delta Pdi) were lower than normal. Lung recoil pressure was normal. Reversible small airways obstruction was also found. Treatment with prednisone produced dramatic improvement, with all functional values becoming normal except for compliance, which remained slightly decreased. A thorough evaluation of inspiratory muscle strength is advised in all patients with DM in order to identify varying degrees of altered diaphragmatic function.

Adult↗

PubMed2002

Prevalence of diaphragmatic muscle weakness and dyspnoea in Graves' disease and their reversibility with carbimazole therapy.

OBJECTIVES: Dyspnoea is a common complaint among patients with thyrotoxicosis. However, its causative mechanisms have not been identified. We assessed the role of thoracic diaphragmatic muscle weakness in dyspnoea among patients with active Graves' disease. METHODS: Twenty-seven patients (19 female, 8 male) with active Graves' disease were assessed for the clinical severity of dyspnoea, functional (pressure generating capacity) and anatomical aspects (thickness and excursion) of the diaphragm at presentation. The severity of dyspnoea was assessed using a visual analogue scale (VAS) and the 6 min walk test. Lung function tests, diaphragmatic strength (sniff oesophageal pressure, SniffP(oeso)), maximum inspiratory and expiratory pressures, diaphragmatic thickness and movements on real time ultrasonography were evaluated during normal and deep respiration. Twenty of the 27 patients were reassessed after achieving euthyroidism with carbimazole therapy at a mean interval of 5+/-2 months. RESULTS: Reevaluation after carbimazole therapy revealed a significant reduction in dyspnoea on the VAS (59+/-26 to 23+/-13%). Patients covered a similar distance during the 6 min walk before and after euthyroidism. Significant improvement was observed in the vital capacity (2.57+/-0.62 to 2.94+/-0.60 l), forced expiratory volume in the first second (2.21+/-0.49 to 2.45+/-0.47 l), total lung capacity (3.57+/-1.19 to 4.1+/-1.12 l), diaphragmatic movement during deep respiration (5.5+/-1.0 to 6.6+/-1.1 cm) and SniffP(oeso) (68.7+/-23 to 93.1+/-25.2 cmH(2)O). There was no significant change in the distance walked in 6 min, tidal volume, lung diffusion capacity and diaphragmatic thickness. There was no significant correlation between the net change in dyspnoea score and net change in lung function tests, diaphragmatic movement and SniffP(oeso). CONCLUSIONS: Significant functional weakness of diaphragm muscle is present in patients with active Graves' disease. This weakness is more marked during a maximal respiratory manoeuvre, indicating a diminished diaphragmatic reserve which could be the cause of dyspnoea observed on exertion among patients with thyrotoxicosis.

Adult↗

PubMed1996

Functional development of the sheep diaphragmatic ligament.

1. The diaphragmatic ligament, which lines the thoracic surface of the diaphragm, plays a major role in setting the passive compliance of the diaphragm in the adult. Since many elastic tissues are more compliant at younger ages, our aim was to determine whether this diaphragmatic ligament plays an important role during development of the diaphragm. 2. We examined the passive biaxial length-tension properties of the isolated mid-costal diaphragm from fetal, newborn and adult sheep; initially with the diaphragm intact and then with the diaphragmatic ligament removed to reveal its functional significance. 3. We found that unlike other elastic tissues the diaphragmatic ligament is stiffer in early development than in the adult. The diaphragmatic ligament supports about 75% of the passive tension in the diaphragm in the 121 day fetus (term at 147 days) declining to about 50% from 3 weeks of age. The fetal diaphragm muscle fibres are exposed to 1-7 kPa of stress over the last 26 days of gestation. 4. We suggest that the diaphragmatic ligament provides a structural framework on which the muscle fibres of the diaphragm grow in fetal life, and that the ligament's elasticity is regulated to maintain a low and constant stress on the diaphragm muscle fibres during development.

Age Factors↗

PubMed1991

[Use of manual reflexotherapy for correcting biomechanical changes in the chest and the functional status of the diaphragmatic neuromuscular complex in patients with tuberculosis].

Abnormal biomechanical changes of the osteoarticular and muscular apparatus of the chest were revealed by the method of manual diagnosis in all 72 examined patients in a tuberculosis clinic. They appeared as various functional blocks in the vertebral motor segments and regional postural muscle imbalance which was attended by lower lung ventilation capacity and dysfunction of the diaphragmatic neuromuscular complex. After the course of manual reflex therapy comprising mobilization, manipulations and postisometric relaxation, 80% of the patients felt easier respiration, lower chest stiffness. There was a significant increase of functional capacities of the external respiratory apparatus in all the patients.

Adolescent↗

PubMed2002

[Indications, techniques and results of laparoscopic surgery for diaphragmatic diseases].

Eleven patients with congenital, traumatic and functional extrahiatal diaphragmatic lesions are reported. Since 1991 two patients with acute, two patients with old ruptures of the diaphragm and one patient with a Morgagni-Larrey-hernia were successfully treated by laparoscopic direct suturing. In two other patients with Morgagni hernias we used a polypropylene mesh for closure of the defect. One procedure was performed in a patient with symptomatic congenital dysplasia of the diaphragm with aplasia of the pericard. Laparoscopic plication of the diaphragm was performed in three symptomatic patients with phrenic nerve palsy after cardiac surgery. The intra- and postoperative course was uneventful in all cases. During a median follow-up of 60 months there was no recurrence. Therefore the laparoscopic technique is an effective and attractive alternative for treatment of these diseases.

Adolescent↗

PubMed2002

Comparison of contractile function of diaphragm and cardiac muscle in response to paired electrical stimulation.

Paired pacing has been shown to potentiate contractile function of cardiac muscle, and it has been suggested that this may enhance contractile function of diaphragmatic muscle. The primary goal of this study was to study the effect of paired pacing on potentiation of contractile function of diaphragmatic muscle compared to atrial and ventricular myocardium. Diaphragmatic muscle was isolated from mouse and rat, and atrial and ventricular myocardium from dogs. Potentiation was induced by isolated extrastimuli (equal in duration and intensity to the pacing stimulus) and by repetitive extrastimuli (i.e. paired pacing) at a paced rate of 12, 30 and 60 beats/min. Baseline studies were performed while preparations were isometrically contracting at L(max) in oxygenated Krebs-Henseleit solution at 28 degrees C. Maximal force generation in response to a premature stimulus was determined at each rate by scanning the coupling interval between paced beats. Under baseline conditions, diaphragmatic muscle contracted faster than atrial and ventricular muscle. In all tissues, maximum potentiation (increase in force above baseline) was approximately 100% of baseline force, and peak potentiation occurred at shorter coupling intervals with increasing rates of stimulation. Single and paired pacing of diaphragm potentiated the contraction during which the extrastimuli were introduced, while in cardiac muscle, extrastimuli potentiated the contraction following the extrastimulus. The maximum potentiated response occurred when the extrastimulus was introduced prior to the development of peak force in diaphragmatic muscle. In contrast, in atrial and ventricular muscle, a single or paired premature stimulus potentiated the subsequent beat when delivered late during relaxation. In cardiac muscle, maximal potentiation gradually occurred following several repetitive stimuli. Following cessation of single and paired pacing, the beat following the potentiated response immediately returned to baseline in diaphragmatic muscle, while a gradual decline was evident over several subsequent beats in cardiac muscle. Increasing the bath temperature from 28 to 37 degrees C resulted in a leftward shift in the peak potentiated force vs. coupling interval curve without a decline in the magnitude of potentiated force in diaphragmatic muscle. In diaphragm muscle, exposure to ryanodine markedly decreased baseline force and maximal potentiation. We conclude that closely timed extrastimuli applied to diaphragmatic muscle can potentiate developed force in a given contraction, while in cardiac tissue a delayed stimulus potentiates the subsequent beat. These differences in contractile responsiveness are not due to differences in loading conditions, but appear to reflect intrinsic differences in calcium handling.

Animals↗

PubMed2001

Incidence of diaphragmatic paralysis following supraclavicular brachial plexus block and its effect on pulmonary function.

Thirty unpremedicated ASA physical status 1-3 patients aged between 18 and 69 years, scheduled for upper limb surgery, received a conventional supraclavicular brachial plexus block using a nerve stimulator and bupivacaine 0.375% 0.5 ml.kg-1. Spirometric measurements of pulmonary function and ultrasonographic assessments of diaphragmatic function were made before the block and at 10-min intervals after injection until full motor block of the brachial plexus had developed. Complete paralysis of the ipsilateral hemidiaphragm occurred in 50% of patients. Seventeen per cent of patients had reduced diaphragmatic movement and the rest (33%) had no change in diaphragmatic movement. Those with complete paralysis all showed significant decreases in pulmonary function, whereas those with reduced or normal movement had minimal change. All patients remained asymptomatic throughout, with normal oxygen saturation on room air.

Adult↗

PubMed2005

[Diaphragmatic weakness and its impact on respiratory function in primary myopathies].

BACKGROUND: Diaphragmatic weakness (DW) is a potential manifestation of primary myopathies. Prevalence and impact on respiratory function have not been defined. METHODS: Respiratory function (inspiratory vital capacity, IVC; maximal inspiratory muscle pressure, PImax; respiratory muscle effort, P (0.1)/PImax) and polysomnography/nocturnal capnometry (PtcCO(2)) was analysed in 49 patients with primary myopathies. DW was defined as > 25 % drop of IVC upon shift from upright to supine position. RESULTS: 19/54 (35 %) of patients, mostly AMD (68 %) and DMD (42 %) had DW. Restrictive ventilatory defect was moderate (IVC 37.2 +/- 26.2 %) in patients with and without DW (IVC 46 +/- 26 %, p = n. s.). DW caused a -33 %, respective - 25 %, supine drop of IVC and PImax, resulting in severe restriction in supine position (IVC (supine) 24.9 +/- 19.1 %, PImax (supine) 2.0 +/- 1.0 kPa, P (0.1)/PImax (supine) 19.9 +/- 12,8 %). All patients with DW and 75 % without had sleep-disordered breathing. This was significantly more severe in DW: 90 % (vs 17 % without DW) had continuous nocturnal hypoventilation (PtcCO(2) 62 +/- 2 mm Hg), 70 % (vs 18 % without DW) had combined nocturnal and diurnal hypercapnic respiratory failure (PaCO(2) 54,7 +/- 11.8 mm Hg). DW was an independent risk factor for sleep disordered breathing, for nocturnal and diurnal respiratory failure (r = 0.95, p < 0,05). Predictive thresholds thereof were accurate and identical to previously determined only for supine function data. CONCLUSION: DW is common in primary myopathies and predictive of nocturnal and diurnal respiratory failure. Supine respiratory function tests are necessary for clinical diagnosis and respiratory risk stratification.

Adolescent↗

PubMed2006

Functional arrangement of rat diaphragmatic initial lymphatic network.

Fluid and solute flux between the pleural and peritoneal cavities, although never documented under physiological conditions, might play a relevant role in pathological conditions associated with the development of ascitis and pleural effusion and/or in the processes of tumor dissemination. To verify whether a pleuroperitoneal flux might take place through the diaphragmatic lymphatic network, the transdiaphragmatic pressure gradient (Delta P(TD)) was measured in five spontaneously breathing anesthetized rats. Delta P(TD) was -1.93 cmH2O (SD 0.59) and -3.1 cmH2O (SD 0.82) at end expiration and at end inspiration, respectively, indicating the existence of a pressure gradient directed from the abdominal to the pleural cavity. Morphometrical analysis of the diaphragmatic lymphatic network was performed in the excised diaphragm of three additional rats euthanized with an anesthesia overdose. Optical and electron microscopy revealed that lymphatic submesothelial lacunae and lymphatic capillaries among the skeletal muscles fibers show the ultrastructural features of the so-called initial lymphatic vessels, namely, a discontinuous basal lamina and anchoring filaments linking the outer surface of the endothelial cells to connective tissue or to muscle fibers. Primary unidirectional valves in the wall of the initial lymphatics allow entrance of serosal fluid into the lymphatic network preventing fluid backflow, while unidirectional intraluminar valves in the transverse vessels convey lymph centripetally toward central collecting ducts. The complexity and anatomical arrangement of the two valves system suggests that, despite the existence of a favorable Delta P(TD), in the physiological condition no fluid bulk flow takes place between the pleural and peritoneal cavity through the diaphragmatic lymphatic network.

Animals↗

PubMed1991

Nocturnal hypoxia in unilateral diaphragmatic paralysis.

Pulmonary function has been studied extensively in patients with unilateral diaphragmatic paralysis (UDP), but there is scarce information regarding the respiratory function during sleep in this condition. We therefore studied pulmonary function in 12 patients with UDP when awake and when asleep. Diaphragmatic dysfunction was confirmed by the demonstration of low maximal transdiaphragmatic pressures in most of our patients; paradoxical gastric pressure swing was observed in 6 patients. There was a restrictive pattern in pulmonary function tests and resting arterial blood gases were rather well preserved (range SaO2 90-95%). Overnight sleep monitoring showed that the time spent in REM sleep and stage 3 and 4 sleep was reduced. The mean maximum decrease in SaO2 was 15.2 +/- 6.2% and the time with an SaO2 drop of more than 5% of the awake SaO2 was 25.4 +/- 22.8 min. None of our patients was in respiratory failure or had clinical evidence of cor pulmonale. We conclude that UDP leads to significant nocturnal hypoxemia but, in the absence of systemic lung disease, does not lead to chronic respiratory failure and cor pulmonale.

Adult↗