MAXIMAL MID‐INSPIRATORY TO MAXIMAL MID‐EXPIRATORY FLOW RATE RATIO IN UPPER AIRWAY OBSTRUCTION

Background —In the Fontan circulation, pulmonary and systemic vascular resistances are in series. The implications of this unique arrangement on infradiaphragmatic venous physiology are poorly understood. Methods and Results —We studied the effects of respiration and gravity on infradiaphragmatic venous flows in 20 normal healthy volunteers (control) and 48 Fontan patients (atriopulmonary connection [APC] n=15, total cavopulmonary connection [TCPC] n=30). Hepatic venous (HV), subhepatic inferior vena caval (IVC), and portal venous (PV) flow rates were measured with Doppler ultrasonography during inspiration and expiration in both the supine and upright positions. The inspiratory-to-expiratory flow rate ratio was calculated to reflect the effect of respiration, and the supine-to-upright flow rate ratio was calculated to assess the effect of gravity. HV flow depended heavily on inspiration in TCPC compared with both control and APC subjects (inspiratory-to-expiratory flow rate ratio 3.4, 1.7, and 1.6, respectively; P <0.0001). Normal PV flow was higher in expiration, but this effect was lost in TCPC and APC patients (inspiratory-to-expiratory flow rate ratio 0.8, 1.0, and 1.1, respectively; P =0.01). The respiratory influence on IVC flow was the same in all groups. Gravity decreased HV flow more in APC than in TCPC patients (supine-to-upright flow rate ratio 3.2 versus 2.1, respectively; P <0.04) but reduced PV flow equally in all groups. Conclusions —Gravity and respiration have important influences on infradiaphragmatic venous return in Fontan patients. Although gravity exerts a significant detrimental effect on lower body venous return, which is more marked in APC than in TCPC patients, the beneficial effects of respiration in TCPC patients are mediated primarily by an increase in HV flow. These effects may have important short- and long-term implications for the hemodynamics of the Fontan circulation.

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Mouth and nose resistance in newborn kittens and puppies

Journal of Applied Physiology ◽

10.1152/jappl.1981.51.3.641 ◽

1981 ◽

Vol 51 (3) ◽

pp. 641-645 ◽

Cited By ~ 7

Author(s):

J. P. Mortola ◽

J. T. Fisher

Keyword(s):

Mechanical Properties ◽

Airway Obstruction ◽

Flow Rate ◽

Muscle Tone ◽

Upper Airway ◽

Upper Airway Obstruction ◽

Upper Airways ◽

Airway Patency ◽

The Difference ◽

Adult Cats

Newborn mammals, including infants, have difficulties in mouth breathing when the nasal passages are occluded. In this study we examined the possibility that differences in the passive mechanical properties of the upper airways could fully explain this behavior. Steady inspiratory flows through the upper airways in anesthetized supine newborn kittens and puppies resulted in upper airway obstruction, even at flows less than those occurring during resting breathing, suggesting that in the unanesthetized condition muscle tone plays an important role in maintaining upper airway patency. Mouth (Rm) and nose (Rn) resistances have been measured during steady expiratory flows with nostrils closed and mouth passively open or nostrils open and mouth closed. In all the newborns, Rn was substantially smaller than Rm. In contrast, the Rn/Rm in adult dogs is greater than unity. In adult cats Rn/Rm is above or below unity depending upon the flow rate, but the ratio is always larger than in newborn kittens. The difference between newborns and adults is entirely due to the small Rn of the newborn, as Rm is not greater in the newborn than in the adult. We conclude that the obligatory nose breathing behavior of newborns is not fully explained by the passive mechanical properties of the upper airways.

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Upper airway obstruction in patients with endothoracic goiter enlargement: no relationship between flow-volume loops and radiological tests

Acta Endocrinologica ◽

10.1530/eje-10-0235 ◽

2010 ◽

Vol 163 (4) ◽

pp. 665-669 ◽

Cited By ~ 12

Author(s):

M Albareda ◽

J Viguera ◽

C Santiveri ◽

P Lozano ◽

A Mestrón ◽

...

Keyword(s):

Airway Obstruction ◽

Vital Capacity ◽

Visual Analysis ◽

Upper Airway ◽

Forced Expiratory Volume ◽

Upper Airway Obstruction ◽

Flow Volume ◽

Flow Parameters ◽

Forced Expiratory Flow ◽

Expiratory Flow

BackgroundIn about 16–85% of subjects with goiter, upper airway obstruction (UAO) is observed. This percentage is higher in patients affected by goiter with endothoracic enlargement. UAO is an indication for surgery. Visual analysis of flow-volume loops (FVL) are the best indicators for UAO, although various studies using clinical and radiological parameters have observed no correlation.ObjectiveTo evaluate the presence of UAO in patients with endothoracic goiter enlargement and the relationship between the FVL with the observed symptoms and the measurements obtained by computed tomography (CT).SubjectsSubjects with endothoracic goiter enlargement participated in the study.Designi) Symptom questionnaire (dysphagia, dyspnea, cough, oppression, dysphonia, and worsened symptoms when prone); ii) analysis: TSH and free thyroxine; iii) cervical ultrasound; iv) cervical-thoracic CT (measurements of area and diameter in the area of maximum stenosis and at 2 cm from the carina); v) chest radiography and vi) forced spirometry: visual analysis of FVL morphology and the maximum forced expiratory volume in 1 s (FEV1), forced expiratory flow at 50% vital capacity/forced inspiratory flow at 50% vital capacity and FEV1/peak expiratory flow parameters.ResultsFifty subjects participated in the study: 11 men/39 women, median age 73.8 years (43.76–88.43). UAO was diagnosed in 13 cases (26%, confidence interval: 14.6–40.3%) and 27 subjects (54%) presented symptoms suggesting goiter compression. No clinical or radiological variables showed the presence of UAO.ConclusionsThe frequency of UAO in subjects affected by goiter with endothoracic enlargement was lower than that described for goiter patients, and there were no clinical or radiological indicators to establish its presence.

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Assessment of upper airway obstruction by measuring peak oral and nasal inspiratory flow

The Journal of Laryngology & Otology ◽

10.1017/s0022215115000523 ◽

2015 ◽

Vol 129 (5) ◽

pp. 473-477 ◽

Cited By ~ 4

Author(s):

S Bathala ◽

R Eccles

Keyword(s):

Airway Obstruction ◽

Phase Ii ◽

Flow Rate ◽

Upper Airway ◽

Inspiratory Flow ◽

Upper Airway Obstruction ◽

University Hospital ◽

Inspiratory Flow Rate ◽

Efficacy Measures ◽

Study Participants

AbstractObjective:We wanted to access upper airway obstruction in patients undergoing tonsillectomy by measuring peak oral and nasal inspiratory airflow.Methods:We recruited study participants from a cohort of patients on the waiting list for tonsillectomy, with or without adenoidectomy, at University Hospital of Wales, Cardiff, UK. Fifty patients enrolled on phase I of the study and underwent pre-operative measurement of the rate of peak oral and nasal inspiratory flow; 25 of these patients returned after one month for phase II of the study and underwent post-operative measurement of the rate of both peak oral and nasal inspiratory flow.Results:Of the 25 participants who completed phase II of the study, 17 (68 per cent) showed an increase in post-operative peak oral inspiratory flow rate by an average of 45 per cent, while 18 (72 per cent) showed an increase in post-operative peak nasal inspiratory flow rate by an average of 22 per cent.Conclusion:Both peak oral and nasal inspiratory flow rate measurements may be useful measures of oral and nasal obstruction. Further larger studies are needed to develop these measurements as screening and efficacy measures for adenotonsillectomy to relieve upper airway obstruction.

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