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PubMed1988

Ultra-high-frequency jet ventilation in a bronchopleural fistula model.

High-frequency ventilation techniques have been demonstrated to be useful in decreasing gas loss from bronchopleural fistulas. We performed the present study to evaluate the impact of a new jet ventilator design and ventilatory frequency on hemodynamics, gas exchange, and bronchialstump gas flow in an animal model of bronchopleural fistula. Ten pigs underwent a right-sided thoracotomy and right-sided upper pulmonary lobectomy with cannulation of the upper lobe bronchus for measurement of bronchial fistula flow rate. Animals underwent a random sequence of conventional ventilation (12 to 20 breaths per minute), conventional high-frequency jet ventilation (120 breaths per minute), and ultra-high-frequency jet ventilation (UHFJV; 450 breaths per minute). Hemodynamic measurements were similar in the three ventilatory modes, but oxygenation was best with UHFJV. Bronchial fistula flow was lowest with UHFJV and greatest with conventional ventilation. Ultra-high-frequency jet ventilation demonstrated superior oxygen loading, adequate carbon dioxide elimination, and the least flow through the fistula, suggesting that both ventilator design and frequency are important therapeutic variables in the management of major airway disruption.

Animals↗
PubMed1992

The functional significance of ventilation frequency, and its relationship to oxygen demand in the resting brown long-eared bat, Plecotus auritus.

Mean oxygen consumption and simultaneous ventilation frequency of nine non-reproductive brown long-eared bats (body mass 8.53-13.33 g) were measured on 159 occasions. Ambient (chamber) temperature at which the measurements were made ranged from 10.8 to 41.1 degrees C. Apneic ventilation occurred in 22 of the 59 measurements made when mean oxygen consumption was less than 0.5 ml.min-1. No records of apneic ventilation were obtained when it was over 0.5 ml.min-1. The relationship between ventilation frequency and mean oxygen consumption depended on whether ventilation was apneic or non-apneic. When ventilation was non-apneic the relationship was positive and log-linear. When ventilation was apneic the relationship was log-log. Within the thermoneutral zone ventilation frequency was not significantly different from that predicted from allometric equations for a terrestrial mammal of equivalent body mass, but was significantly greater than that predicted for a bird. A reduction in the amount of oxygen consumed per breath occurred at ambient temperatures above the upper critical temperature (39 degrees C).

Animals↗
PubMed1993

Non-invasive modalities of positive pressure ventilation improve the outcome of acute exacerbations in COLD patients.

OBJECTIVE: 1) To compare the clinical usefulness of both non-invasive pressure support ventilation (NPSV) and non-invasive intermittent positive pressure ventilation in assist-control (A/C) mode (NIPPV) in chronic obstructive lung disease (COLD) patients with acute hypercapnic respiratory failure: 2) to compare retrospectively the usefulness of non-invasive mechanical ventilation (NMV) with standard medical therapy alone. DESIGN: Prospective randomized retrospective study. SETTING: 2 Respiratory intermediate intensive units. PATIENTS: 29 COLD patients (age: 62 +/- 8 years) with chronic respiratory failure were hospitalized in a department for rehabilitation during acute relapses of their disease. They were transferred to our intermediate intensive care unit (IICU) and submitted randomly to either NPSV (16 patients) or NIPPV (13 patients). MEASUREMENTS AND RESULTS: Blood gas analysis, dynamic flows, clinical variables, success rate, time of ventilation, side effects and subjective score of compliance to therapy. Therapy was considered successful when endotracheal intubation was avoided and patients were returned to their condition prior to exacerbation. No statistically significant difference was found between NPSV and NIPPV in success rate (NPSV 87.5%; NIPPV 77%) or in time of ventilation (NPSV: 69 +/- 49; NIPPV: 57 +/- 49 h). A better compliance to non-invasive mechanical ventilation (NMV) was found in NPSV patients than in NIPPV patients; side effects were observed less frequently in the NPSV group. Comparison of the success rate of NMV was retrospectively performed with 35 control COLD patients with chronic respiratory insufficiency who had undergone an acute relapse of their disease in the 2 years preceding the institution of the IICU and had been treated with oxygen and medical therapy alone. Patients submitted to NMV showed a greater success rate than control (82 versus 54%) after a period of ventilation ranging from 4-216 h. CONCLUSION: Non-invasive mechanical ventilation performed either by NPSV or NIPPV may improve the outcome of acute exacerbations of COLD, as compared to medical therapy alone. NPSV seems to be more acceptable to patients in comparison with NIPPV.

Acute Disease↗
PubMed1987

Effects of high-frequency jet ventilation on intracranial pressure in experimental head-brain injury.

Based on experimental studies, ventilation with small volumes of gas and rates of up to 100-400/minute, high-frequency jet ventilation (HFJV), seems to present a true alternative to conventional intermittent positive pressure ventilation (IPPV), especially in patients with multiple organ damage. In order to determine the effects of high-frequency jet ventilation on intracranial pressure, we examined the effects of the HFJV in comparison to conventional ventilation in experimental balloon brain trauma. Ten young pigs were studied using continuous invasive hemodynamic, pulmonary, and intracranial pressure monitoring. There was no increase in brain pressure over normal ventilation. As a matter of fact, there was a temporary decrease of the intracranial pressure by about 5 mmHg, which returned to the initial pre-HFJV value after 5 minutes. In contrast to conventional ventilation, HFJV allows for tracheobronchial suctioning and interruption of ventilation without any noticeable increase of ICP.

Animals↗
PubMed1986

ICU monitoring of ventilation distribution.

The oxygen washin method has been shown to be a practical way to measure functional residual capacity (FRC) in the intensive care unit. The ventilator oxygen concentration is increased and measurements of respiratory flow and oxygen concentration at the mouth are made with the patient monitoring system. No additional personnel, bedside equipment or ventilator attachments are required. A feasibility study was performed to determine if this method could be used to estimate a continuous distribution of ventilation with respect to ventilation to volume ratio VA/V. Due to gas mixing in the ventilator, the inspired oxygen fraction does not increase instantaneously to its new value. An equation was derived which models the lung as 50 discrete compartments and accounts for the transient change in mean inspired oxygen fraction. A digital computer simulation demonstrated good distribution recovery for one and two mode ventilation distributions. Continuous distributions were computed for four post cardiac surgery patients at four levels of positive end expiratory pressure (PEEP). In these patients a linear increase in the amount of ventilation in the normal VA/V range occurred with increasing PEEP, i.e., slow and fast spaces tended to move centrally toward a more normal VA/V range. At zero PEEP 26% of the ventilation occurred in the normal range and this increased to 49% at 15 PEEP. Dead space fraction was poorly estimated and spurious modes occurred in the high VA/V range.

Cardiac Surgical Procedures↗
PubMed2000

Nitric oxide and high frequency jet ventilation in a patient with bilateral bronchopleural fistulae and ARDS.

PURPOSE: To describe a method of delivering nitric oxide during high frequency jet ventilation. CLINICAL FEATURES: A 63-yr-old man underwent reduction pneumoplasty for bullous emphysema. Postoperatively, ventilation was inadequate, secondary to bilateral high output bronchopleural fistulae. High frequency jet ventilation was initiated and achieved adequate ventilation (pH>7.2). Over the following 24 hr, progressive hypoxemia (SaO2 <86%) developed along with the acute respiratory distress syndrome. Nitric oxide was delivered by continuous flow at the patient Y-connector during combined high frequency jet and conventional ventilation (two conventional low volume breaths/minute). Substantial improvement in oxygenation (FiO2 0.8 0.5, SaO2 >92%) was noted initially and was sustained over 72 hr. Subsequently, the patient was weaned to conventional ventilation without difficulty. Mechanical ventilation was discontinued on postoperative day sixteen. CONCLUSION: The simultaneous use of nitric oxide and high-frequency jet ventilation was used safely and effectively in this patient as a method of support for acute respiratory distress syndrome with co-existing large bilateral bronchopleural fistulae.

Bronchial Fistula↗
PubMed1996

[Adaptive lung ventilation (AVL). Evaluation of new closed loop regulated respiration algorithm for operation in the hyperextended lateral position].

The lateral decubitus position is the standard position for nephrectomies. There is a lack of data about the effects of this extreme position upon respiratory mechanics and gas exchange. In 20 patients undergoing surgery in the nephrectomy position, we compared a new closed-loop-controlled ventilation algorithm, adaptive lung ventilation (ALV), which adapts the breathing pattern automatically, to the respiratory mechanics with conventionally controlled mandatory ventilation (CMV). The aims of our study were (1) to describe positioning effects on respiratory mechanics and gas exchange, (2) to compare ventilatory parameters selected by the ALV controller with traditional settings of CMV, and (3) to assess the individual adaptation of the ventilatory parameters by the ALV controller. The respirator used was a modified Amadeus ventilator, which is controlled by an external computer and possesses an integrated lung function analyzer. In a first set of measurements, we compared parameters of respiratory mechanics and gas exchange in the horizontal supine position and 20 min after changing to the nephrectomy position. In a second set of measurements, patients were ventilated with ALV and CMV using a randomized crossover design. The CMV settings were a tidal volume of 10 ml/kg body weight, a respiratory rate of 10 breaths/min, an I:E ratio of 1:1.5, and an end-inspiratory pause of 30% of inspiratory time. With both ventilation modes F1O2 was set to 0.5 and PEEP to 3 cm H2O. During ALV a desired alveolar ventilation of 70 ml/ kg KG.min was preset. All other ventilatory parameters were determined by the ALV controller according to the instantaneously measured respiratory parameters. Positioning induced a reduction of compliance from 61.6 to 47.9 ml/cm H2O; the respiratory time constant shortened from 1.2 to 1.08 s, whereas physiological dead space increased from 158.9 to 207.5 ml. On average, the ventilatory parameters selected by the ALV controller resembled very closely those used with CMV. However, an adaptation to individual respiratory mechanics was clearly evident with ALV. In conclusion, we found that the effects of positioning for nephrectomy are minor and may give rise to problems only in patients with restrictive lung disease. The novel ALV controller automatically selects ventilatory parameters that are clinically sound and are better adapted to the respiratory mechanics of ventilated patients than the standardized settings of CMV are.

Adult↗
PubMed1997

[The effect of fresh-gas decoupling on respiratory volume. Draegar Sulla 808V anesthesia ventilator].

UNLABELLED: In order to perform accurate low-flow anaesthesia ventilation, it is desirable to avoid the influence of fresh gas flow (FGF) and inspiration duration (ID) on the resulting minute volume (MV). The Sulla 808V anaesthesia ventilator (Draeger, Luebeck, Germany) is originally not equipped with a fresh-gas decoupling (FGD) device. Therefore, changes of FGF and ID settings applied during controlled ventilation may lead to alterations of the resulting MV. Recently, a low-cost FGD device (Carbamed, Bern-Liebefeld, Switzerland) has been developed, which can be inserted into the circle system. We investigated the effect of this device on MV in the Sulla 808V anaesthesia apparatus. METHODS: The performance of a Sulla 808V anaesthesia ventilator was tested with and without a FGD device. During ventilation of a test lung, stepwise changes of tidal volume (400-1000 ml), FGF (0.5-10 l/min), and ID (0.25-0.5) settings were consecutively applied, and the resulting MV was recorded. Correlation and mean prediction error between ventilation parameter settings and MV were calculated. RESULTS: In the presence of a FGD device, the administered MV was not affected by the magnitude of FGF and ID. A mean prediction error (bias) of -3.6 l/min of the resulting MV was observed. Without FGD the bias was only-1.8 l/min, while FGF and ID revealed a pronounced influence on MV. These effects were statistically significant when using FGF exceeding 4 l/min. CONCLUSIONS: The tested FGD device can easily be integrated into the circle system of conventional anaesthesia machines such as the Draeger Sulla 808V, and is available at a reasonable cost. It allows constant ventilation parameters to be maintained that remain unaffected by wide FGF and ID variations. With this FGD the performance of the ventilator can be improved considerably, and low-flow anaesthesia can be used more extensively.

Humans↗
PubMed1997

[Recommendations of Bavarian Muscle Centers of the German Neuromuscular Disease Society for home ventilation of neuromuscular diseases of adult patients].

During recent years home ventilation has been shown to be useful for a growing number of patients with neuromuscular diseases and respiratory insufficiency caused by weakness of the respiratory muscles. Despite its technical simplicity, home ventilation leads to a number of social, ethical, medical and infrastructural problems. This consensus paper discusses the special situation of patients with neuromuscular diseases in home ventilation and describes the current thinking in the following topics: (1) definition of home ventilation; (2) aims of home ventilation; (3) indications and preconditions of home ventilation; (4) techniques and forms of home ventilatory support; (5) preparation for and practical questions of home ventilation; (6) stopping home ventilation.

Adult↗
PubMed2002

Kinetic and reversibility of mechanical ventilation-associated pulmonary and systemic inflammatory response in patients with acute lung injury.

OBJECTIVE: To investigate the kinetic and reversibility of mechanical ventilation-associated pulmonary and systemic inflammatory response in patients with acute lung injury (ALI). DESIGN: Prospective observational cross-over study. SETTING: Intensive care unit of a university hospital. PATIENTS: Twelve mechanically ventilated patients with ALI. INTERVENTIONS: Mechanical ventilation was transiently changed from a lung protective setting with PEEP of 15 cmH(2)O and a V(T) of 5 ml/kg predicted body weight to a more conventional ventilatory setting with PEEP of 5 cmH(2)O and V(T) of 12 ml/kg predicted body weight for a period of 6 h. MEASUREMENTS AND RESULTS: We examined the profile of interleukin (IL)-1beta, IL-1 receptor antagonist, IL-6, IL-10, and tumor necrosis factor in the plasma of all patients, and in the bronchoalveolar lavage (mini-BAL) fluid of six of these patients. Measurements were performed at baseline, 1 h, and 6 h after each change of the ventilatory setting. Switching to conventional mechanical ventilation was associated with a higher PaO(2) ( P < 0.05) and a marked increase ( P < 0.05) of measured plasma cytokines in patients with and without mini-BAL with a maximum after 1 h. Similarly, intraalveolar cytokine concentrations increased with conventional mechanical ventilation. While plasma cytokine levels returned to baseline values, intraalveolar cytokine concentrations further increased when lung protective mechanical ventilation was reestablished. CONCLUSIONS: In patients with ALI, initiation of low PEEP and high V(T) mechanical ventilation is associated with cytokine release into circulation which occurred within 1 h. It is independent from BAL procedures and can be reversed by reinstitution of lung protective mechanical ventilation.

Bronchoalveolar Lavage Fluid↗
PubMed2003

Alveolar recruitment of atelectasis under combined high-frequency jet ventilation: a computed tomography study.

OBJECTIVE: To quantify the effect of superimposed high-frequency jet ventilation on lung recruitment in adult patients with acute lung injury. DESIGN AND SETTING: Prospective clinical study in the intensive care unit of a university teaching hospital. PATIENTS: Eight adults suffering from acute lung injury with a mean lung injury score of 2.6+/-0.6 and pronounced atelectasis in at least two lung quadrants. The cause was either pneumonia ( n=5) or postoperative sepsis ( n=3). INTERVENTIONS: Superimposed high-frequency jet ventilation was initiated in patients following a mean of 4.4+/-1.7 days of conventional ventilation. Before and 4 h after the start of superimposed high-frequency jet ventilation differential lung volumes were determined by volumetry using computed tomography. MEASUREMENTS AND RESULTS: Superimposed high-frequency jet ventilation significantly increased the lung volume of every patient due to alveolar recruitment. This was achieved despite lower peak inspiratory pressures and higher PaO(2)/FIO(2) ratios than with conventional ventilation. CONCLUSIONS: Treatment with superimposed high-frequency jet ventilation for 4 h resulted in rapid alveolar recruitment in dependent lung areas, improved gas exchange, and better arterial oxygenation. It offers an effective and advantageous alternative to conventional ventilation for ventilatory management of respiratory insufficient patients.

Adult↗
PubMed2004

Non-invasive negative and positive pressure ventilation in the treatment of acute on chronic respiratory failure.

OBJECTIVE: To investigate in clinical practice the role of non-invasive mechanical ventilation in the treatment of acute respiratory failure on chronic respiratory disorders. DESIGN: An 18 months prospective cohort study. SETTING: A specialised respiratory intensive care unit in a university-affiliated hospital. PATIENTS: A total of 258 consecutive patients with acute respiratory failure on chronic respiratory disorders. INTERVENTIONS: Criteria for starting non-invasive mechanical ventilation and for endotracheal intubation were predefined. Non-invasive mechanical ventilation was provided by positive pressure (NPPV) ventilators or iron lung (NPV). RESULTS: The main characteristics of patients (70% with chronic obstructive pulmonary disease) on admission were (mean, SD or median, 25th-75th centiles): pH 7.29 (0.07), PaCO(2) 83 mm Hg (19), PaO(2)/FiO(2) 198 (77), APACHE II score 19 (15-24). Among the 258 patients, 200 (77%) were treated exclusively with non-invasive mechanical ventilation (40% with NPV, 23% with NPPV, and 14% with the sequential use of both), and 35 (14%) with invasive mechanical ventilation. In patients in whom NPV or NPPV failed, the sequential use of the alternative non-invasive ventilatory technique allowed a significant reduction in the failure of non-invasive mechanical ventilation (from 23.4 to 8.8%, p=0.002, and from 25.3 to 5%, p=0.0001, respectively). In patients as a whole, the hospital mortality (21%) was lower than that estimated by APACHE II score (28%). CONCLUSIONS: Using NPV and NPPV it was possible in clinical practice to avoid endotracheal intubation in the large majority of unselected patients with acute respiratory failure on chronic respiratory disorders needing ventilatory support. The sequential use of both modalities may increase further the effectiveness of non-invasive mechanical ventilation.

APACHE↗
PubMed2006

Body and head position effects on regional lung ventilation in infants: An electrical impedance tomography study.

OBJECTIVE: To determine the effects of body and head positions on the spatial distribution of ventilation in nonintubated spontaneously breathing and mechanically ventilated infants using electrical impedance tomography (EIT). DESIGN AND SETTING: Prospective study in a neonatal intensive care unit. PATIENTS: Ten spontaneously breathing (gestational age 38 weeks, postnatal age 13 days) and ten mechanically ventilated infants (gestational age 35 weeks, postnatal age 58 days). INTERVENTIONS: Supine and prone postures with different head positions (midline and rotated to the left and right side). MEASUREMENTS AND RESULTS: The distribution of ventilation in the chest cross-section was repeatedly determined from EIT data in each body/head position studied. During spontaneous breathing the tidal volumes in the left lung region were reduced in the supine posture with the head turned to the left as well as in the prone posture with the head rotated to either side when compared with the supine posture with the head in the midline position. During mechanical ventilation the tidal volumes in the left lung region were unaffected by the body and head position except for the prone posture combined with the leftward head rotation which reduced them. In both types of ventilation the tidal volumes in the right lung region were unaffected by the change in body/head position. CONCLUSION: The results indicate that the spatial distribution of ventilation is influenced by the body and head position in spontaneously breathing infants. Prone posture with the leftward head rotation has the most prominent effect which is detectable even during mechanical ventilation.

Electric Impedance↗
PubMed2003

Hypothermia attenuates vascular manifestations of ventilator-induced lung injury in rats.

Alveolar hemorrhage and pulmonary edema induced by mechanical ventilation are partly dependent on cardiac output. Because cardiac output is low during hypothermia, we hypothesized that hypothermia may protect against these vascular manifestations of ventilator-induced lung injury. Twenty-seven Sprague-Dawley rats were assigned to either normothermia (37 +/- 1 degrees C)-injurious ventilation (NT; n = 10), hypothermia (27 +/- 1 degrees C)- injurious ventilation (HT; n = 10), or nonventilated control ( n = 7). The two ventilated groups were subjected to injurious ventilation of peak airway pressure 30 cm H(2)O with zero end-expiratory pressure for 20 min. Compared with the NT group, the hemorrhage/congestion score of the lung (11.2 +/- 1.5 vs. 4.7 +/- 1.6; p < 0.001) and the ratio of wet/dry lung weight (6.1 +/- 0.8 vs. 5.0 +/- 0.1; p = 0.046) of the HT group were lower. Compared with the NT group, protein concentration (3,471 +/- 1,985 micro g/ml vs. 1,374 +/- 726 micro g/ml; p = 0.003) and lactate dehydrogenase level (0.43 +/- 0.22 U/ml vs. 0.18 +/- 0.1 U/ml; p = 0.046) in bronchoalveolar lavage fluid of the HT group were lower. Whereas pressure-volume curve was shifted to the right in the NT group after injurious ventilation, it was not shifted in the HT group. In conclusion, hypothermia in rats attenuated the degrees of vascular manifestations and alveolar epithelial injuries induced by injurious ventilation, and preserved the mechanical properties of the lung.

Animals↗
PubMed2006

Electrical impedance tomography: changes in distribution of pulmonary ventilation during laparoscopic surgery in a porcine model.

BACKGROUND: Because of the creation of a pneumoperitoneum, impairment of ventilation is a common side-effect during laparoscopic surgery. Electrical impedance tomography (EIT) is a method with the potential for becoming a tool to quantify these alterations during surgery. We have studied the change of regional ventilation during and after laparoscopic surgery with EIT and compared the diagnostic findings with computed tomography (CT) scans in a porcine study. MATERIALS AND METHODS: After approval by the local animal ethics committee, six pigs were included in the study. Two laparoscopic operations were performed [colon resection (n=3) and fundoplicatio (n=3)]. The EIT measurements (6th parasternal intercostal space) were continuously recorded by an EIT prototype (EIT Evaluation Kit, Dräger Medical, Lübeck, Germany). To verify ventilatory alterations detected by EIT, a CT scan was performed postoperatively. RESULTS: Ventilation with defined tidal volumes was significantly correlated to EIT measurements (r2=0.99). After creation of the pneumoperitoneum, lung compliance typically decreased, which agreed well with an alteration of the distribution of pulmonary ventilation measured by EIT. Elevation of positive end-inspiratory pressure reopened non-aerated lung areas and showed a recovery of the regional ventilation measured by EIT. Additionally, we could detect pulmonary complications by EIT monitoring as verified by CT scans postoperatively. CONCLUSION: EIT monitoring can be used as a continuous non-invasive intraoperative monitor of ventilation to detect regional changes of ventilation and pulmonary complications during laparoscopic surgery. These EIT findings indicate that surgeons and anesthetists may eventually be able to optimize ventilation directly in the operating theatre.

Animals↗
PubMed1991

Controlled ventilation during NMR spectroscopic studies: hemodynamic and biochemical consequences.

The effects of different ventilation methods on cardiac output measured by the indicator-dilution method, liver blood flow measured by a deuterium washout technique using 2H nuclear magnetic resonance (NMR) and liver concentrations of ATP and intracellular pH determined with 31P NMR were compared in anesthetized rats. No differences in mean arterial blood pressure were demonstrable with the different modes of ventilation. However, significant drops in cardiac output were observed between freely breathing and animals ventilated with positive pressure but not the high frequency oscillatory method (407 +/- 46 and 520 +/- 88 vs. 633 +/- 86 ml/min/kg, p less than 0.05 and p = NS, respectively). Moreover, liver blood flow was significantly reduced during positive pressure but not high frequency oscillatory ventilation compared with free breathing rats (32 +/- 4 and 43 +/- 10 vs. 46 +/- 8 ml/100 g, p less than 0.05 and p = NS, respectively). 31P NMR spectroscopy revealed no effects of either ventilation method on tissue ATP or intracellular pH as estimated by the chemical shift of inorganic phosphate. These data suggest that controlled ventilation in normal rats accomplished with standard positive pressure methods is associated with major decreases in cardiac output and liver blood flow despite maintenance of normal blood pressure. High frequency oscillatory ventilation appears to effect less compromise of cardiac output and hepatic perfusion than positive pressure ventilation and may, therefore, be preferable for some biological studies.

Animals↗
PubMed2004

Ventilation imaging of the lung: comparison of hyperpolarized helium-3 MR imaging with Xe-133 scintigraphy.

RATIONALE AND OBJECTIVES: To compare hyperpolarized helium-3 (HHe) magnetic resonance imaging (MRI) of the lung with standard Xe-133 lung ventilation scintigraphy. MATERIALS AND METHODS: We performed a retrospective review of 15 subjects who underwent HHe MRI and Xe-133 lung ventilation imaging. Coronal MRI sections were acquired after a single inhalation of HHe gas, and standard posterior planar lung ventilation scintigraphy was performed during continuous breathing of Xe-133 gas. The first breath scintigram of each patient was compared with a composite MR image composed of the sum of the individual MR images and with the individual helium-3 MR images. Ventilation defects on the two imaging modalities were compared for size, conspicuity, and concordance in presence and location. Assessment was done separately for each of four lung quadrants. RESULTS: Comparing the composite HHe MR images with Xe-133 scintigraphy, ventilation defect size, conspicuity and concordance were the same in 67% (40/60), 63% (38/60), and 62% (37/60) quadrants, respectively. Comparing the individual HHe MR image sections with the Xe-133 ventilation scan, there was concordance between the ventilation defects in 27% (16/60) of quadrants. More defects were identified on the individual HHe MR images in 62% (37/60) of quadrants. CONCLUSION: There was good agreement between composite HHe MR image and first breath Xe-133 scintigraphic images, supporting the widely held assumption that HHe MRI likely depicts first breath lung ventilation.

Adolescent↗
PubMed2006

Non-ventilation during early incubation in combination with dexamethasone administration during late incubation: 1. Effects on physiological hormone levels, incubation duration and hatching events.

This study investigated the effect of non-ventilation of the incubator during the first 10 days of incubation and its combination with dexamethasone administration at day 16 or 18 of incubation on hatching parameters and embryo and post-hatch chick juvenile physiology. A total of 2400 hatching eggs produced by Cobb broiler breeders were used for the study. Blood samples were collected at day 18 of incubation, at internal pipping stage (IP), at the end of hatch (day-old chick) and at 7-day-post-hatch for T(3), T(4) and corticosterone levels determination. From 448 to 506 h of incubation, the eggs were checked individually in the hatcher every 2h for pipping and hatching. The results indicate that non-ventilation during the first 10-day shortened incubation duration up to IP, external pipping (EP) and hatch, had no effect on hatchability and led to higher T(3) levels at IP but lower corticosterone levels at 7-day-post-hatch. The injection of dexamethasone at days 16 and 18 of incubation affected hatching and blood parameters in both the ventilated and non-ventilated embryos differentially and the effect was dependent on the age of the embryo. Dexamethasone increased T(3) levels and T(3)/T(4) ratios but the effect was greater with early non-ventilation of eggs. Dexamethasone decreased hatchability but the effect was greater when injected at day 16 and especially in ventilated embryos. The effects of incubation protocols and dexamethasone treatments during incubation were still apparent in the hatched chicks until 7 days of age. The changes in T(3), T(4) and corticosterone levels observed in response to the early incubation conditions and late dexamethasone treatments in this study suggest that incubator ventilation or non-ventilation may influence the hypothalamic-pituitary-adrenal axis (HPA) regulation of stress levels (in terms of plasma corticosterone levels) and thyroid function in the embryo with impact on incubation duration, hatching events and early post-hatch life of the chick. Our results also suggest that some stages of development are more sensitive to dexamethasone administration as effects can be influenced by early incubation protocols.

Animals↗