Tidal Breathing Flow-volume Loops Research Articles

5 LUNG FUNCTION TESTING(LFT) IN UPPER AIRWAY OBSTRUCTION(UAO) AND FLEXIBLE BRONCHOSCOPY(FB) IN PRETERM AND TERM INFANTS

Typical deformation of tidal breathing flow-volume-loops (TBFV) and passive expiration loops (single breath occlusion technique) are suspicious of UAO. FB identifies the pathoanatomic structure. Aim of the study was to determine the usefulness of LFT for identification and follow-up of UAO.

Management of severe congenital tracheobronchomalacia by continuous positive airway pressure and tidal breathing flow‐volume loop analysis

We report on a now 9-month-old infant with severe tracheobronchomalacia associated with campomelic dysplasia. The diagnosis of tracheobronchomalacia was suggested in the neonatal period by typical changes of the tidal breathing flow-volume loop and was confirmed by tracheobronchoscopy. Tidal breathing flow-volume loop analysis also allowed to titrate the optimal, continuous positive airway pressure for the respiratory management of the patient. Since bedside pulmonary function testing is noninvasive and rapid, it may reduce the need for frequent bronchoscopic evaluations in the management of patients with tracheobronchomalacia.

Tidal breathing flow-volume loop analysis as a test of pulmonary function in exercising horses

Summary The usefulness of tidal breathing flow-volume loops (tbfvl) to evaluate pulmonary function was investigated in 6 Standardbreds during treadmill exercise. Tidal breathing flow-volume loops are a graphic representation of airflow rate vs tidal volume for each individual breath. These tbfvl were obtained from horses exercising at speeds corresponding to 75 and 100% of maximum heart rate. Measurements were recorded in each horse before and after ovalbumin-induced allergic lung disease. Moderate obstructive lung disease, characterized by a significant increase in pulmonary resistance, was observed while the horses were at rest. We found that in horses with airway obstruction exercising at 75 or 100% of maximum heart rate, the quantitative indices describing tbfvl shape and size were not markedly different from those in clinically normal horses exercising at similar speeds.

Evaluation of partial arytenoidectomy as a treatment for equine laryngeal hemiplegia.

The efficacy of partial arytenoidectomy was assessed in 6 Standardbred horses, with surgically induced laryngeal hemiplegia, at rest (Period A) and during exercise at speeds corresponding to maximum heart rate (Period C) and 75% of maximum heart rate (Period B). Peak expiratory and inspiratory airflow rate (PEF and PIF), and expiratory and inspiratory transupper airway pressure (PUE and PUI) were measured and expiratory and inspiratory impedance (ZE and ZI) were calculated. Simultaneously, tidal breathing flow-volume loops (TBFVL) were acquired using a respiratory function computer. Indices derived from TBFVL included airflow rates at 50 and 25% of tidal volume (EF50, IF50, EF25, and IF25) and the ratios of expiratory to inspiratory flows. Measurements were made before left recurrent laryngeal neurectomy (baseline), 2 weeks after left recurrent laryngeal neurectomy (LRLN) and 16 weeks after left partial arytenoidectomy coupled with bilateral ventriculectomy (ARYT). After LRLN, during exercise Periods B and C, Z1 and the ratio of EF50/IF50 significantly increased and PIF, IF50 and IF25 significantly decreased from baseline values. At 16 weeks after ARYT, Z1 returned to baseline values during Periods B and C. Although PIF, IF50, IF25, PEF/PIF, and EF50/IF50 returned to baseline values during Period B, these indices remained significantly different from baseline measurements during Period C. After ARYT, TBFVL shapes from horses during Period C approached that seen at the baseline evaluation. Partial arytenoidectomy improved upper airway function in exercising horses with surgically induced left laryngeal hemiplegia, although qualitative and quantitative evaluation of TBFVLs suggested that some flow limitation remains at near maximal airflow rates. These results indicate that, although the procedure does not completely restore the upper airway to normal, partial arytenoidectomy is a viable treatment option for failed laryngoplasty and arytenoid chondropathy in the horse.

Tidal breathing flow-volume loops in healthy and bronchitic cats.

Tidal breathing flow-volume loops (TBFVL) were obtained from 19 healthy cats and 7 cats with chronic bronchial disease. Peak inspiratory flow (PIF) occurred late in the inspiratory cycle and was preceded by a gradual but more linear increase in the flow rate. Peak expiratory flow (PEF) occurred early during expiration and was followed by a curvilinear decrease in flow to a point near the end of expiration where flow ceased. The loops obtained were generally reproducible. The mean coefficient of variation (CV) for TBFVL indices of healthy cats ranged from 5.6% to 21.9%. Loop indices from cats with chronic bronchial disease had a mean CV between 6.6% and 28.4%. Significant differences were noted in the bronchitic cats' TBFVLs, including an increased ratio of expiratory time to inspiratory time, lower expiratory flow rates, decreased area under total and peak expiratory flow curves, and decreased tidal breathing expiratory volumes (TBEV) at 0.1 and 0.5 seconds. Selected TBFVL indices were also significantly reduced. TBFVL evaluation in the cat is easy to perform, is reproducible, and has allowed for the detection of changes during tidal breathing in cats with histories and physical findings of chronic lower airway disease.

Use of flow-volume loops to evaluate upper airway obstruction in exercising Standardbreds

Summary Flow-volume loops generated from 6 Standardbreds at rest and during treadmill exercise were evaluated for their use in detecting upper airway obstruction. Tidal breathing flow-volume loops (tbfvl) were obtained from horses at rest and exercising at speeds corresponding to 75% of maximal heart rate and at maximal heart rate. The tbfvl were evaluated, using a pulmonary function computer; calculated indices describing airflow rate and expiratory-to-inspiratory airflow ratio for individual loops were determined. In addition to tbfvl indices, standard variables of upper airway function also were measured: peak airflow, peak pressure, and calculated inspiratory and expiratory impedances. Measurements were recorded before left recurrent laryngeal neurectomy (lrln; baseline) and 14 days after surgically induced left laryngeal hemiplegia. When horses were at rest, tbfvl shape and indices describing the loop were highly variable. In contrast, in exercising horses, tbfvl shape was consistent and coefficients of variation of loop indices were less during exercise than at rest. After lrln, tbfvl from exercising horses indicated marked inspiratory airflow limitation, while the expiratory airflow curve was preserved. Peak inspiratory flow rate and inspiratory flow at 50 and 25% of tidal volume decreased, and the ratio of peak expiratory to inspiratory airflow and that of midtidal volume expiratory and inspiratory airflow rates increased significantly (P < 0.05). Inspiratory impedance also increased after lrln. Although in resting horses tbfvl were not a useful indicator of upper airway obstruction, examination of tbfvl from exercising horses allowed objective, specific, and repeatable detection of upper airway obstruction. The technique was noninvasive, rapid, and well tolerated by horses; thus, it is a potentially valuable clinical diagnostic test.

An experimental evaluation of castellated laryngofissure and bilateral arytenoid literalisation for the relief of laryngeal paralysis in dogs

The aim of this study was to compare the efficacy of 2 surgical procedures for providing an adequate laryngeal airway in dogs after surgically induced laryngeal paralysis. The laryngeal function of 10 healthy, adult experimental dogs was assessed by clinical examination, laryngoscopy, arterial blood gas measurement and analysis of tidal breathing flow-volume loops before, and after, bilateral recurrent laryngeal neurectomy. A castellated laryngofissure with vocal fold resection was done on 5 dogs and bilateral arytenoid cartilage lateralisation performed on the remaining 5 dogs. Six weeks later, the laryngeal function of the 10 dogs was reassessed, before the dogs were killed and a necropsy performed. The visible changes in laryngeal structure were recorded. Both surgical procedures alleviated some of the airway obstruction caused by the bilateral recurrent laryngeal neurectomy, but bilateral arytenoid cartilage lateralisation produced more consistent clinical improvement, a wider rima glottidis, increased inspiratory air flow and a significant increase in post-operative arterial oxygen tension.

Thoracoabdominal Asynchrony in Acute Upper Airway Obstruction in Small Children

The assessment of the severity and response to therapy of acute upper airway obstruction (UAO) in small children relies on subjective parameters. Using a noncalibrated respiratory inductance plethysmograph (RIP), we quantitated the rib cage (RC) to abdominal (AB) asynchrony and the lag phase in chest wall expansion by the phase angle from the RC versus AB signal curve. Phase angles were obtained in 17 children aged 1 to 50 months with acute UAO and 30 normal control subjects. The phase angle in UAO (16 to 165 degrees; mean = 83.6 degrees) was significantly higher than in control subjects (3 to 25 degrees; mean = 11.5 degrees), p less than 0.001. Following 29 episodes of inhalation treatment with 0.03 ml/kg of racemic epinephrine, the phase angle in the UAO group decreased to 7 to 160 degrees (mean = 38.3; p = 0.001) as the shape of the RC versus AB loop became narrower. In response to the treatment, the clinical severity of UAO decreased and the tidal breathing flow-volume loop improved. A high association was observed between the phase angle and the degree of stridor (p less than 0.005 Fisher's exact test), and in 90% (26 of 29) the changes in the phase angle and in the degree of stridor were in agreement. We conclude that the RC-AB asynchrony in acute UAO can be objectively quantitated by phase-angle measurement from a noncalibrated RIP and is thus suitable for use in infants and small children. The phase angle may be used to assess objectively the response of UAO to therapy.

Canine Chronic Bronchitis

Eighteen dogs with chronic bronchitis were studied using physiologic, radiologic, microbiologic, and pathologic techniques. Twelve of these dogs were evaluated before and after two weeks of oral bronchodilator administration. Thoracic radiographs, tidal breathing flow-volume loops, radioaerosol ventilation scans, airway appearance at bronchoscopy, and airway pathology were abnormal in the majority of dogs studied. There was a significant relationship between abnormal ventilation scans and abnormal results for PaO2 and end-tidal airflow. Bronchoscopy revealed excessive mucus and inflammation of airway mucosa in all 16 dogs undergoing this procedure. Endoscopically obtained aerobic bacterial cultures grew mixed bacterial flora in only three dogs. Increased numbers of neutrophils in 14 dogs were detected by airway lavage cytology. A large number of eosinophils were seen in airway lavages obtained from two dogs; these two dogs also had evidence for eosinophilic bronchitis on endobronchial biopsy. Oral bronchodilator administration resulted in clinical and expiratory airflow improvements in most dogs, but had no effect on PaO2 or on the radioaerosol-scan abnormalities. The presence of both the physiologic and pathologic airway abnormalities of chronic bronchitis in dogs presented to a veterinary hospital with chronic unexplained cough was confirmed, suggesting that aerobic bacteria do not play an etiologic role in most cases.

The effect of common bovine respiratory diseases on tidal breathing flow-volume loops.

In order to better understand the bovine breathing pattern, tidal breathing flow-volume loops (TBFVL) were analyzed in 24 healthy cattle of different body weights (range: 37–660 kg) (Group A) and in 28 cattle suffering from the common respiratory diseases: verminous bronchitis (Group B); shipping fever (Group C); acute respiratory distress syndrome (Group D); respiratory syncytial virus pneumonia (Group E); organophosphate poisoning (Group F); and necrotic laryngitis (Group G).Respiratory airflow and tidal volume were measured with a breathing mask-Fleisch pneumotachograph assembly. TBFVL were traced from these values using a computerized method. All the loop indices proposed by Amis and Kurpershoek (1986a) were calculated from 5 representative breathing cycles for each of the 52 animals.The TBFVL shapes and indices were relatively constant in most healthy cattle and were not correlated with the body size. When compared to normal values, animals with moderate respiratory syndromes (Groups B and C) had a more flattened shape to their TBFVL. On the other hand, in most cattle with severe respiratory pathologies (Groups D, F and G) expiration tended to be biphasic with the peak expiratory flow (PEF) occurring significantly later than in healthy animals. Both PEF and peak inspiratory flow were increased in all the pathological conditions. The TBFVL indices were more frequently and more severely changed during expiration than during inspiration.

TRACHEAL DIAMETERS AND DYNAMICS IN INFANTS AND CHILDREN MEASURED BY CINE-CT

Nine children were evaluated for tracheal obstruction by having their intra- and extra-thoracic tracheal diameters measured using Cine-CT. The patients ranged in age from one month to four years, and had clinical signs and symptoms of respiratory distress with stridor. They entered a protocol in which there was full clinical evaluation, and in some, measurement of esophageal pressures and tidal breathing flowvolume loops. The patients were scanned without sedation using a Cine-CT scanner (Imatron, Inc., CA) which provided eight level image acquisition in 240 msec without moving the patients. Using the scanner in the “Cine” mode, 13 to 20 slices obtained over 1 to 2 respiratory cycles were obtained at several levels of both the intra-and extra-thoracic trachea to detail dynamic changes in airway caliber. Images were obtained at relatively low dose and were reconstructed in 14 seconds. Cross-sectional areas of the trachea were obtained by planimetry, and saggital and coronal tracheal diameters directly measured. The clinical and laboratory data correlated well with the imaging measurements, and were compared with Age-related normal Cine-Ct tracheal diameters, and published post-mortem airway caliber data. We conclude that Cine-CT is a rapid method for tomographic evaluation of tracheal dynamics that can be employed for children without sedation.

The use of the tidal breathing flow volume loop in laryngotracheal disease of neonates and infants

AbstractFlow volume loops have been valuable in the diagnosis of upper airway obstruction in adults; however, the use of this technique in neonates has been limited because of their inability to perform a forced exhalation. We have used the tidal breathing flow volume loop (TBFV) to evaluate upper airway function in 100 neonates and infants. Eleven of the neonates and infants tested with this method were found to have laryngotracheal abnormalities such as tracheal stenosis, innominate artery compression, subglottic hemangioma, and unilateral vocal cord paralysis.Normal neonates and infants demonstrate a round or oval TBFV loop pattern, while those with upper airway obstruction show a flat inspiratory or expiratory curve.Tidal breathing flow volume loops offer a new, rapid and noninvasive method for evaluating the upper airway function in neonates and infants, and may play an important role in diagnosing upper airway dysfunction and evaluating the need for therapeutic intervention.