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PubMed2001

Respiratory system compliance and postoperative ventilator dependence in neonates with left-sided congenital diaphragmatic hernia.

PURPOSE: The purpose of this prospective consecutive patient study was to test if perioperative respiratory system compliance of patients undergoing surgical repair of congenital diaphragmatic hernia (CDH) can predict the need for prolonged postoperative mechanical ventilation. METHODS: All neonates over 35 weeks of gestation who had surgical repair of left-sided CDH between July 1994 and December 1996 ( n = 10) were included in this study. Static respiratory system compliance (C(rs)) was measured by the passive occlusion method with muscle relaxation before (C(pre)) and after (C(post)) surgical repair of left-sided CDH. We examined the relationship between respiratory system compliance and postoperative ventilator-dependent duration. RESULTS: The mean birthweight-corrected C(post) was lower than that of birthweight-corrected C(pre) (0.41 +/- 0.18 vs 0.54 +/- 0.18 ml.cm H(2)O(-1).kg(-1), P = 0.04). One neonate died on postoperative day 31 from intraventricular hemorrhage, and the other nine neonates survived. The patient who died was excluded from the rest of our calculations. The ventilator-dependent duration was 16.7 +/- 12.3 days. The postoperative ventilator-dependent duration was longer when the birthweight-corrected C(post) was smaller, with a significant correlation between these parameters ( P = 0.006). CONCLUSION: C(post), but not C(pre), may be useful to predict the need for prolonged postoperative mechanical ventilation in neonates with left-sided CDH.

Journal Article↗
PubMed1996

Effect of nitric oxide inhalation on respiratory system resistance in chronic obstructive pulmonary disease.

Nitric oxide (NO) has been identified as a neurotransmitter of nonadrenergic noncholinergic bronchodilator nerves. To investigate whether inhaled NO exerts a bronchodilator effect in patients with chronic obstructive pulmonary disease (COPD), we measured the resistance of the respiratory system, using the forced oscillation technique, while breathing NO. Eight patients with COPD (7 men and 1 woman; aged 66 +/- 7 yrs (mean +/- SD); forced expiratory volume in one second (FEV1) 37 +/- 17% of predicted) and eight healthy subjects (7 men and 1 woman; 33 +/- 4 yrs; FEV1 108 +/- 14% pred) were studied. Nitric oxide, at a concentration of 40 parts per million (ppm) in air, was inhaled for 20 min. Total resistance (Rrs) and reactance (Xrs) of the respiratory system, arterial oxygen saturation, heart rate, tidal volume, and breathing frequency were continuously recorded at baseline, and during and after ceasing NO inhalation. Methaemoglobin levels were additionally measured in healthy subjects. At baseline, patients with COPD showed higher Rrs than healthy subjects (Rrs at 10 Hz (Rrs,10) 4.97 +/- 2.19 vs 2.29 +/- 0.65 hPa.L-1.s). During NO inhalation, no significant change in Rrs or in Xrs was observed. Mean variation in Rrs,10 while breathing NO was negligible and similar in the two groups (-0.10 +/- 0.13 hPa.L-1.s in COPD patients and -0.02 +/- 0.13 hPa.L-1.s in healthy subjects). Moreover, there were no differences in oxygen saturation, heart rate, tidal volume and breathing frequency during NO inhalation. Methaemoglobinaemia increased at the end of NO inhalation (from 0.48 +/- 0.18 to 0.81 +/- 0.16%), and this increment remained 10 min later (0.86 +/- 0.31%). From these results, we conclude that inhaled nitric oxide, at a concentration of 40 ppm, exerts no effect on respiratory system resistance in patients with chronic obstructive pulmonary disease or in healthy subjects.

Administration, Inhalation↗
PubMed1992

Mortality from respiratory system cancer in New South Wales and Sydney.

Differential and spatial analyses of respiratory system cancer were undertaken for New South Wales and Sydney for the period 1980-1986. The source of data was death certificate information on the unit list mortality file tapes provided by the Australian Bureau of Statistics. Characteristics of persons dying included age, sex, birthplace, occupational status and cause of death (ICD9 classification). The aim was to identify populations at risk from respiratory system cancer, and where they were located. Deaths were disaggregated for the abovementioned categories by cross-tabulation at the state level and for geographical areas having populations with higher levels of respiratory cancer mortality. Never-married males of lower occupational status had higher rates of respiratory cancer, mainly lung cancer. Divorced men also had higher mortality as did widowers who were in lower occupational status work, while married men in managerial work also had significantly high mortality. The marital status variation was mostly not found with females, although significantly high female mortality was found in several low socioeconomic status areas of Sydney. Mortality of both sexes was significantly higher in metropolitan Sydney than in the rest of New South Wales and associations between older age mortality and some industrial areas were found in Sydney.

Adolescent↗
PubMed2002

The respiratory system in varanid lizards: determinants of O(2) transfer.

Varanids in general exhibit greater aerobic capacities than other lizards. In a similar approach to the extensive investigations undertaken in mammals, the respiratory system in varanids is examined in terms of oxygen transfer from the air to the blood during rest and sustained locomotory activity. The parameters controlling the transfer of O(2) through the various steps of the respiratory system are appropriate to meet the maximum demands for oxygen with one possible exception, circulatory convection. Ventilatory convection is maintained during maximal aerobic locomotion ensuring adequate pulmonary ventilation and the protection of alveolar P(O(2)). Little evidence exists to indicate a mechanically imposed constraint to breathe and the possibility of a gular pump acting to assist ventilation, as a general feature of varanids remains to be determined. Alterations in the relative contributions of the ventilation-perfusion ratio, pulmonary diffusion, diffusion equilibrium and right-left shunts preserved the alveolar-arterial P(O(2)) difference, ensuring that arterial oxygenation was maintained. In those species where increases in cardiac output were limited, maximum O(2) transfer was achieved through increased extraction of oxygen at the tissues. Overall, the interrelationship of adjacent steps in the respiratory system ensures that one step cannot become limiting. Compensatory changes occur in various parameters to offset those parameters that are 'limited'. The high aerobic activity of varanid lizards would not be achievable without a compensated circulatory convection.

Animals↗
PubMed2005

General pharmacology of CKD-732, a new anticancer agent: effects on central nervous, cardiovascular, and respiratory system.

CKD-732 [6-O-(4-dimethylaminoethoxy) cinnamoyl fumagillol hemioxalate] is a new fumagillin anticancer drug that belongs to an angiogenesis inhibitor. Its effect on the central nervous system (CNS), general behavior, cardiovascular-respiratory system and the other organ systems were studied. CKD-732 was intravenously administered with the dosages of 10, 30, 40 or 50 mg/kg and the highest dosage of 50 mg/kg prolonged the hexobarbital-induced sleep time. CKD-732 at the dosage of 50 mg/kg, also, caused the decrease of body temperature from 15 to 120 min after the administration, which was recovered at 240 min. In the study of the effects on gastric secretion, CKD-732 induced the increase of pH and decrease of total acidity. However, CKD-732 showed no effect on general behavior, spontaneous locomotor activity, motor coordination, analgesia, convulsion, mean arterial pressure, and cardiac functions except for heart rate of isolated rat heart, respiration, isolated smooth muscle, intestinal charcoal transport and renal function. Based on the results, we suggested that CKD-732 is safe general pharmacologically at clinical supposed dose (1.75 mg/kg) and demonstrated to have much better safety than other fumagillin derivatives.

Animals↗
PubMed1996

The respiratory system and homeostasis.

Respiratory homeostasis is concerned with the regulation of a blood gas composition that is compatible with maintaining cellular homeostasis. Provided that the lung-capillary exchange barrier does not prevent the exchange of gases, then blood leaving the lung will have oxygen and carbon dioxide partial pressures that are similar to the average values found in the alveoli. Alveolar ventilation establishes these values. If blood gas composition, especially of carbon dioxide, moves outside the homeostatic range, the change is detected by chemoreceptors and respiratory responses are promoted which change alveolar ventilation, alter alveolar gas composition and so reverse the change. Ventilation therapies provide the means of artificially restoring alveolar gas composition. In general terms, they do this by raising the partial pressure of oxygen within the alveoli either by using oxygen-enriched gas mixtures, or by improving the ventilation of alveoli using positive pressure.

Blood Gas Analysis↗
PubMed1992

Lung, chest wall, and total respiratory system resistances and elastances in the normal range of breathing.

We measured total respiratory system and lung and chest wall resistances (Rrs, Rl, and Rcw) and elastances (Ers, El, and Ecw) in awake, relaxed human subjects during sinusoidal volume forcing at the mouth from 0.2 to 0.6 Hz with tidal volumes (VT) of 6 to 18% VC at constant mean airway pressure. In addition, we repeated measurements with the lowest VT at a lower airway pressure and therefore at a lower mean lung volume (Vl). Rrs and Rcw decreased with increasing respiratory frequency (f) and VT, but Rl was independent of f and VT. All resistances were higher at the lower Vl. Ers and Ecw increased with increasing f and decreased with increasing VT. El increased slightly with increasing f but was not affected by VT. All elastances tended to increase at the lower Vl. We conclude that in the normal range of breathing amplitude and frequency, (1) lung properties are nearly constant if mean lung volume does not change, and (2) f and VT dependencies of total respiratory system properties are caused by the chest wall.

Adult↗
PubMed2003

Computer-controlled mechanical simulation of the artificially ventilated human respiratory system.

A mechanical lung simulator can be used to simulate specific lung pathologies, to test lung-function equipment, and in instruction. A new approach to mechanical simulation of lung behavior is introduced that uses a computer-controlled active mechatronic system. The main advantage of this approach is that the static and dynamic properties of the simulator can easily be adjusted via the control software. A nonlinear single-compartment mathematical model of the artificially ventilated respiratory system has been derived and incorporated into the simulator control system. This model can capture both the static and dynamic compliance of the respiratory system as well as nonlinear flow-resistance properties. Parameters in this model can be estimated by using data from artificially ventilated patients. It is shown that the simulation model fits patient data well. This mathematical model of the respiratory system was then matched to a model of the available physical equipment (the simulator, actuators, and the interface electronics) in order to obtain the desired lung behavior. A significant time delay in the piston motion control loop has been identified, which can potentially cause oscillations or even instability for high compliance values. Therefore, a feedback controller based on the Smith-predictor scheme was developed to control the piston motion. The control system, implemented on a personal computer, also includes a user-friendly interface to allow easy parameter setting.

Airway Resistance↗
PubMed1995

Assessment of respiratory system compliance by a flow recording method.

Standard methods for the assessment of the compliance of the respiratory system require recordings of both airway pressure and ventilatory volume. A method based on the recording of respiratory flow only, with no need of measuring airway pressure was reported some years ago. The purpose of the present study was to test a modification of this flow-recording technique. The technique is based on the measurement of inspiratory flow with and without the addition of a source of external compliance added to the inspiratory circuit. The difference in inspiratory flow between these two situations can be used to derive the compliance of the respiratory system. The method was and in patients with acute respiratory failure, and compared with a standard method based on airway pressure and inspiratory gas flow recording. Model experiments showed strong correlation between the new flow-recording method and the standard method (r = 0.99, P < 0.001) with a coefficient of variation of less than 2% with both methods. In patients with acute respiratory failure, the flow and standard methods gave similar results when no end-inspiratory pause was applied (mean difference 5 +/- 40 ml/kPa (x +/- s.d.)). The standard method gave significantly higher compliance values, different from the flow method, when an end-inspiratory pause of 10% was applied (mean difference 53 +/- 2 ml/kPa, P < 0.01). The flow method was not influenced by the use of an end-inspiratory pause.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗
PubMed1994

[Occupational exposure of workers in chemical factors and selected parameters of the respiratory system].

Workers employed in chemical factories are chronically exposed to harmful substances present in the air of the occupational environment. The aim of this paper was to find out whether this situation produces adverse effects on the respiratory system despite the observance of admissible concentrations of toxic substances in the air. Spirometric values such as FVC1 and FEV1%FVC were measured in 647 workers. It was found that workers in some departments (power station and polystyrene) showed restrictive and obturative disturbances of ventilation. In other departments workers exhibited less expressed respiratory disorders. Adverse effect of smoking and long period of employment on the respiratory system of workers was also revealed. These results indicate that apart from substances present in the occupational environment there are other factors which affect as well the respiratory system of persons employed in the chemical industry.

Adult↗
PubMed1996

Distribution of two VIP-related peptides, helospectin and pituitary adenylate cyclase activating peptide (PACAP), in the human upper respiratory system.

Helospectin (HS) and pituitary adenylate cyclase activating peptide (PACAP) are newly discovered peptides isolated from the salivary gland venom of the lizard Heloderma horridum and the ovine hypothalamus, respectively. They show chemical similarities to vasoactive intestinal polypeptide (VIP), appear to have similar functions and are present in gut, brain, lung, male and female genitourinary tract. In the present study, the distribution of the helospectin and PACAP-27 in the human upper respiratory system was investigated using indirect immunofluorescence and electron-microscopical ABC-pre-embedding methods. Immunohistochemistry revealed helospectin-like (HS-LI) and PACAP-like (PACAP-LI) immunoreactivity in nerve fibers in human nasal, the larynx (vocal cord, ventricular fold, epiglottis), the tongue and the soft palate mucosa. Helospectin-LI and PACAP-LI containing nerve fibers were mainly found in close association to blood vessels and glandular structures. Colocalization studies carried out by application of double immunofluorescence showed that HS and/(or) PACAP-LI coexist with VIP in apparently the same nerve fibers in the upper respiratory system, although single nerve fibers seem to exclusively express helospectin. The localization patterns of helospectin and PACAP-LI in the human upper respiratory system suggests their possible involvement in the regulation of secretory activities and local blood flow.

Humans↗
PubMed1968

Studies on halotolerance in a moderately halophilic bacterium. Effect of betaine on salt resistance of the respiratory system.

The role of betaine as a factor influencing the salt resistance of the respiratory system in resting cells of the moderately halophilic halotolerant bacterium Ba(1) was studied. Betaine accelerated succinate oxidation in cells obtained from low-salt medium, and stimulation of the respiratory rate was stronger the higher the sodium chloride concentration in the assay medium. The stimulatory effect also depended on the ratio of betaine concentration to the amount of bacteria present. Accumulation of labelled betaine by the bacterial cells was demonstrated; like the respiratory stimulation, it was favourably influenced by an increase in the sodium chloride concentration of the medium. In cells harvested from a high-salt medium and washed with 2.0m-sodium chloride, betaine caused no increase in the respiratory rate, nor was the already high salt resistance of the respiratory system further improved by the addition of betaine. When, however, these cells lost their salt resistance as a result of washing in the absence of sodium chloride, betaine was able to restore it to its original level. In contrast with respiration in low-salt-grown bacteria, that in high-salt-grown cells was not affected by betaine, even after they were washed in the absence of sodium chloride, when the sodium chloride concentration was optimum.

Bacteria↗
PubMed2005

Effects of PEEP on the intracranial system of patients with head injury and subarachnoid hemorrhage: the role of respiratory system compliance.

BACKGROUND: Positive end-expiratory pressure (PEEP) can be effective in improving oxygenation, but it may worsen or induce intracranial hypertension. The authors hypothesized that the intracranial effects of PEEP could be related to the changes in respiratory system compliance (Crs). METHODS: A prospective study investigated 21 comatose patients with severe head injury or subarachnoid hemorrhage receiving intracranial pressure (ICP) monitoring who required mechanical ventilation and PEEP. The 13 patients with normal Crs were analyzed as group A and the 8 patients with low Crs as group B. During the study, 0, 5, 8, and 12 cm H2O of PEEP were applied in a random sequence. Jugular pressure, central venous pressure (CVP), cerebral perfusion pressure (CPP), intracranial pressure (ICP), cerebral compliance, mean velocity of the middle cerebral arteries, and jugular oxygen saturation were evaluated simultaneously. RESULTS: In the group A patients, the PEEP increase from 0 to 12 cm H2O significantly increased CVP (from 10.6 +/- 3.3 to 13.8 +/- 3.3 mm Hg; p < 0.001) and jugular pressure (from 16.6 +/- 3.1 to 18.8 +/- 3.2 mm Hg; p < 0.001), but reduced mean arterial pressure (from 96.3 +/- 6.7 to 91.3 +/- 6.5 mm Hg; p < 0.01), CPP (from 82.2 +/- 6.9 to 77.0 +/- 6.2 mm Hg; p < 0.01), and mean velocity of the middle cerebral arteries (from 73.1 +/- 27.9 to 67.4 +/- 27.1 cm/sec; F = 7.15; p < 0.001). No significant variation in these parameters was observed in group B patients. After the PEEP increase, ICP and cerebral compliance did not change in either group. Although jugular oxygen saturation decreased slightly, it in no case dropped below 50%. CONCLUSIONS: In patients with low Crs, PEEP has no significant effect on cerebral and systemic hemodynamics. Monitoring of Crs may be useful for avoiding deleterious effects of PEEP on the intracranial system of patients with normal Crs.

Adult↗
PubMedDate not supplied

Compliance of the total respiratory system in healthy preterm and full-term newborns.

The compliance of the total respiratory system (CRS) was determined by the occlusion technique during expiration in 19 preterm newborns (NB) over 31 weeks of gestational age (mean, 34 +/- 1.5 SD) and in 20 full-term NB. Postnatal age ranged from 1 to 28 days. No sedation was used during the test. In absolute terms, CRS was significantly greater (P less than 0.01) in full-term than in preterm NB (3.17 +/- 0.71 ml/cm H2O vs 2.37 +/- 0.81 ml/cm H2O). When normalized for body weight, length cubed, [corrected] body surface area, and the Quetelet index (body weight/length squared) [corrected], CRS was similar in preterm and full-term NB. These results suggest that, normalized for biometric data, passive elastic properties of the total respiratory system are similar in full-term and preterm NB, at least in the gestation age range studied.

Compliance↗
PubMed1998

Single-breath method for assessing the viscoelastic properties of the respiratory system.

In order to explain the time dependency of resistance and elastance of the respiratory system, a linear viscoelastic model (Maxwell body) has been proposed. In this model the maximal viscoelastic pressure (Pvisc.max) developed within the tissues of the lung and chest wall at the end of a constant-flow (V') inflation of a given time (tI) is given by: Pvisc,max = R2V'(1-e(-tI/tau2), where R2 and tau2 are, respectively, the resistance and time constant of the Maxwell body. After rapid airway occlusion at t1, tracheal pressure (Ptr) decays according to the following function: Ptr(t) = Pvisc(t) + Prs,st = Pvisc,max(etocc/tau2)+ Prs,st, where tocc/is time after occlusion and Prs,st is static re-coil pressure of the respiratory system. By fitting Ptr after occlusion to this equation, tau2 and Pvisc,max are obtained. Using these values, together with the V' and tI pertaining to the constant-flow inflation preceding the occlusion, R2 can be calculated from the former equation. Thus, from a single breath, the constants tau2, R2 and E2 (R2/tau2) can be obtained. This method was used in 10 normal anaesthetized, paralysed, mechanically ventilated subjects and six patients with acute lung injury. The results were reproducible in repeated tests and similar to those obtained from the same subjects and patients with the time-consuming isoflow, multiple-breath method described previously.

Adult↗
PubMed2001

Influence of pneumoperitoneum and patient positioning on respiratory system compliance.

STUDY OBJECTIVE: To investigate the influence of pneumoperitoneum (PP) and posture on respiratory compliance and ventilation pressures. DESIGN: Prospective, single blind trial. PATIENTS: 10 female ASA physical status I and II patients scheduled for elective gynecologic laparoscopy. SETTING: University medical center. INTERVENTIONS: Anesthesia was performed as total IV anesthesia (TIVA) with propofol, alfentanil, and atracurium. After induction of anesthesia and orotracheal intubation, the lungs were ventilated to maintain partial pressure of CO(2) (P(ET)CO(2)) of 30 +/- 3 mmHg. Ventilation was kept constant. As gas mixture oxygen and air 1:1 was used without positive end-expiratory pressure (PEEP). MEASUREMENTS: Measurements were taken before and after creation of pneumoperitoneum with an intraabdominal pressure (IAP) of 10 mmHg, of 15 mmHg in 20 degrees head-down tilt, then in 20 degrees head-up tilt, and after deflation of PP. We determined peak inspiratory pressure (PIP), mean airway pressure (mPaw), P(ET)CO(2), expiratory minute volume (V(E)), heart rate (HR), and systolic (SBP), diastolic (DBP), and mean arterial pressure (MAP). Respiratory system compliance (C(eff rs)) was calculated as quotient of tidal volume (V(T)) and PIP. MAIN RESULTS: After creation of PP (IAP 10 mmHg), there was a significant increase of median PIP (3 cmH(2)O), mPaw (1 cm H(2)O) and arterial pressure (BP), (MAP by 7 mmHg), C(eff rs) decreased by 6 mL. cm H(2)O(-1). Increase of IAP to 15 mmHg led to a further increase of PIP (2 cm H(2)O) and mPaw (1 cm H(2)O), and a further decrease of C(eff rs) by 5 mL cm H(2)O(-1); BP decreased (MAP by 5.5 mmHg). Head-up or head down positions showed no significant hemodynamic or pulmonary changes. P(ET)CO(2)increased from 29.5 to 36 mmHg at an IAP of 15 mmHg, but then no further changes were noticed. Five minutes after deflation of pneumoperitoneum all values returned to baseline levels. CONCLUSIONS: Creation of PP at an IAP of 15 mmHg reduced respiratory system compliance, and increased peak inspiratory and mean airway pressures, which quickly returned to normal values after deflation. Head-down or head-up position did not further alter those parameters.

Adult↗
PubMedDate not supplied

The effect of mannose-binding protein gene polymorphisms in recurrent respiratory system infections in children and lung tuberculosis.

Mannose-binding lectin (MBL) is able to bind pathogens as an opsonin and plays an important role in the innate immunity. The aim of the present study was to determine the frequencies of the MBL gene variants in the Turkish population and to examine the presence of any association between MBL variants and development of tuberculosis (TB) in adults and recurrent respiratory tract infections in children. Two structural gene mutations in exon 1 of MBL gene (codon 54 and codon 57) were studied. The overall distribution of genotypes did not significantly differ between controls and TB patients/children with recurrent respiratory system infections. The frequency of allele B was calculated as 0.14, 0.09 and 0.06 for control, TB patients and children with recurrent respiratory system infections, respectively. It was found to be significantly lower in children with recurrent respiratory system infections than in controls (chi2: 4.68, d.f: 1, p: 0.030).

Adult↗
PubMedDate not supplied

[The morphofunctional state of the respiratory system in 18-27-year-old persons living in Uzbekistan].

The morphofunctional state of the respiratory system was studied in 2104 male Uzbeks aged 18-27 years from rural and urban areas. The chest circumference, frontal and sagittal diameters, respiratory excursion and vital capacity, breath holding were found to be higher in the rural males in almost all age groups than in the urban ones, suggesting that the latter had a low activity. The increase in the diametrical chest sizes mainly occurred by the asthenic type in the rural males and by the hyperstenic type in the urban ones. Unlike the urban males, the rural ones showed a more developed respiratory system and its rather higher functional and adaptive capacities. There was a close correlation of the total sizes of the body with the morphological signs of the chest and their low correlation with the external respiratory functional parameters.

Adolescent↗