Global and Regional Tidal Volume Distribution in Spontaneously Breathing Mechanically Ventilated Children

Background: Ultrasound guided fluid assessment in management of septic shock has come up as an adjunct to the current gold standard Central Venous Pressure monitoring. This study was designed to observe the respiro-phasic variation of IVC diameter (RV-IVCD) in invasively mechanically ventilated and spontaneously breathing paediatric patients of fluid refractory septic shock.Methods: This was a prospective observational study done at Paediatric intensive Care Unit (PICU) in Paediatric ward of Jawaharlal Nehru Medical College and Hospital (JNMCH) from February 2016 to June 2017. 107 consecutive patients between 1 year to 16 years age who were in shock despite 40ml/kg of fluid administration were included. Inferior Vena Cava (IVC) diameters were measured at end-expiration and end inspiration and the IVC collapsibility index was calculated. Simultaneously Central Venous Pressure (CVP) was recorded. Both values were obtained in ventilated and non-ventilated patients. Data was analysed to determine to look for the profile of RV-IVCD and CVP in ventilated and non-ventilated cases.Results: Out of 107 patients, 91 were on invasive mechanical ventilation and 16 patients were spontaneously breathing. There was a strong negative correlation between central venous pressure (CVP) and inferior vena cava collapsibility (RV-IVCD) in both spontaneously breathing (-0.810) and mechanically ventilated patients (-0.700). Negative correlation was significant in both study groups in CVP <8 mmHg and only in spontaneously breathing patients in CVP 8-12 mmHg range. IVC collapsibility showed a decreasing trend with rising CVP in both spontaneously breathing and mechanically ventilated patients.Conclusion: Ultrasonography guided IVCCI appears to be a valuable index in assessing fluid status in both spontaneously breathing and mechanically ventilated septic shock patients. However, more data is required from the paediatric population so as to define it as standard of practice.

Download Full-text

Impact of delivered tidal volume on the occurrence of intraventricular haemorrhage in preterm infants during positive pressure ventilation in the delivery room

Archives of Disease in Childhood - Fetal and Neonatal Edition ◽

10.1136/archdischild-2017-313864 ◽

2018 ◽

Vol 104 (1) ◽

pp. F57-F62 ◽

Cited By ~ 19

Author(s):

Qaasim Mian ◽

Po-Yin Cheung ◽

Megan O’Reilly ◽

Samantha K Barton ◽

Graeme R Polglase ◽

...

Keyword(s):

Brain Injury ◽

Tidal Volume ◽

Preterm Infants ◽

Positive Pressure Ventilation ◽

Intraventricular Haemorrhage ◽

Delivery Room ◽

Positive Pressure ◽

Reference Ranges ◽

The Mean ◽

Spontaneously Breathing

Background and objectivesDelivery of inadvertent high tidal volume (VT) during positive pressure ventilation (PPV) in the delivery room is common. High VT delivery during PPV has been associated with haemodynamic brain injury in animal models. We examined if VT delivery during PPV at birth is associated with brain injury in preterm infants <29 weeks’ gestation.MethodsA flow-sensor was placed between the mask and the ventilation device. VT values were compared with recently described reference ranges for VT in spontaneously breathing preterm infants at birth. Infants were divided into two groups: VT<6 mL/kg or VT>6 mL/kg (normal and high VT, respectively). Brain injury (eg, intraventricular haemorrhage (IVH)) was assessed using routine ultrasound imaging within the first days after birth.ResultsA total of 165 preterm infants were included, 124 (75%) had high VT and 41 (25%) normal VT. The mean (SD) gestational age and birth weight in high and normal VT group was similar, 26 (2) and 26 (1) weeks, 858 (251) g and 915 (250) g, respectively. IVH in the high VT group was diagnosed in 63 (51%) infants compared with 5 (13%) infants in the normal VT group (P=0.008).Severe IVH (grade III or IV) developed in 33/124 (27%) infants in the high VT group and 2/41 (6%) in the normal VT group (P=0.01).ConclusionsHigh VT delivery during mask PPV at birth was associated with brain injury. Strategies to limit VT delivery during mask PPV should be used to prevent high VT delivery.

Download Full-text

Electrical Impedance Tomography for Assessment of Pendelluft and Work of Breathing in Spontaneously Breathing Mechanically Ventilated Patients

10.1164/ajrccm-conference.2021.203.1_meetingabstracts.a2803 ◽

2021 ◽

Author(s):

E. Kistler ◽

M.S. Schaefer ◽

E. Baedorf Kassis

Keyword(s):

Electrical Impedance Tomography ◽

Electrical Impedance ◽

Work Of Breathing ◽

Impedance Tomography ◽

Mechanically Ventilated ◽

Mechanically Ventilated Patients ◽

Spontaneously Breathing ◽

Ventilated Patients

Download Full-text

Development of a method to measure regional perfusion of the lung in anesthetized ponies using computed tomography angiography and the maximum slope model

American Journal of Veterinary Research ◽

10.2460/ajvr.21.03.0035 ◽

2022 ◽

pp. 1-9

Author(s):

Adam Auckburally ◽

Görel Nyman ◽

Maja K. Wiklund ◽

Anna K. Straube ◽

Gaetano Perchiazzi ◽

...

Keyword(s):

Ct Angiography ◽

Lung Tissue ◽

Lung Perfusion ◽

Therapeutic Interventions ◽

Maximum Slope ◽

Mechanically Ventilated ◽

Regional Lung ◽

Microsphere Method ◽

Perfusion Measurements ◽

Spontaneously Breathing

Abstract OBJECTIVE To develop a method based on CT angiography and the maximum slope model (MSM) to measure regional lung perfusion in anesthetized ponies. ANIMALS 6 ponies. PROCEDURES Anesthetized ponies were positioned in dorsal recumbency in the CT gantry. Contrast was injected, and the lungs were imaged while ponies were breathing spontaneously and while they were mechanically ventilated. Two observers delineated regions of interest in aerated and atelectatic lung, and perfusion in those regions was calculated with the MSM. Measurements obtained with a computerized method were compared with manual measurements, and computerized measurements were compared with previously reported measurements obtained with microspheres. RESULTS Perfusion measurements obtained with the MSM were similar to previously reported values obtained with the microsphere method. While ponies were spontaneously breathing, mean ± SD perfusion for aerated and atelectatic lung regions were 4.0 ± 1.9 and 5.0 ± 1.2 mL/min/g of lung tissue, respectively. During mechanical ventilation, values were 4.6 ± 1.2 and 2.7 ± 0.7 mL/min/g of lung tissue at end expiration and 4.1 ± 0.5 and 2.7 ± 0.6 mL/min/g of lung tissue at peak inspiration. Intraobserver agreement was acceptable, but interobserver agreement was lower. Computerized measurements compared well with manual measurements. CLINICAL RELEVANCE Findings showed that CT angiography and the MSM could be used to measure regional lung perfusion in dorsally recumbent anesthetized ponies. Measurements are repeatable, suggesting that the method could be used to determine efficacy of therapeutic interventions to improve ventilation-perfusion matching and for other studies for which measurement of regional lung perfusion is necessary.

Download Full-text

Effect of body position on spontaneous respiratory rate and tidal volume in patients with obesity, abdominal distension and ascites

American Journal of Critical Care ◽

10.4037/ajcc1994.3.2.102 ◽

1994 ◽

Vol 3 (2) ◽

pp. 102-106 ◽

Cited By ~ 74

Author(s):

SM Burns ◽

MB Egloff ◽

B Ryan ◽

R Carpenter ◽

JE Burns

Keyword(s):

Tidal Volume ◽

Respiratory Rate ◽

Breathing Pattern ◽

Body Position ◽

Abdominal Distension ◽

The Body ◽

Abdominal Distention ◽

Optimal Position ◽

Nursing Textbooks ◽

Spontaneously Breathing

BACKGROUND: Nursing textbooks and tradition suggest that the high-Fowler's position is best to optimize diaphragmatic excursion and effective breathing pattern. The optimal position for intubated patients with obesity, ascites or abdominal distention has yet to be determined but is important because weaning trial outcomes may reflect the effect of position rather than weaning trial tolerance. OBJECTIVE: To determine the body position that optimizes breathing pattern (tidal volume and respiratory rate) in spontaneously breathing, intubated patients with a large abdomen. METHODS: Nineteen intubated patients with abdominal distention, ascites or obesity who were on continuous positive airway pressure or the pressure support ventilation mode were studied in the 0 degrees, 45 degrees, 90 degrees and reverse Trendelenburg's at 45 degrees positions for 5 minutes prior to data collection. RESULTS: The RT at 45 degrees position resulted in a significantly larger tidal volume and lower respiratory rate than the 90 degrees position in intubated, spontaneously breathing patients with a large abdomen. The 45 degrees position resulted in a significantly lower respiratory rate than at 90 degrees; however, no difference in tidal volume was demonstrated. DISCUSSION: A high respiratory rate and low tidal volume potentiates atelectasis and ultimately failure to wean. It is important that the effect of positioning on breathing pattern in intubated patients be determined so that care planning results in optimal outcomes. CONCLUSIONS: The results of this study have implications for the selection of chair and bed positioning during weaning trials.

Download Full-text

Management of hypercapnia in critically ill mechanically ventilated patients—A narrative review of literature

Journal of the Intensive Care Society ◽

10.1177/1751143720915666 ◽

2020 ◽

Vol 21 (4) ◽

pp. 327-333

Author(s):

Ravindranath Tiruvoipati ◽

Sachin Gupta ◽

David Pilcher ◽

Michael Bailey

Keyword(s):

Mechanical Ventilation ◽

Tidal Volume ◽

Dead Space ◽

Hypercapnic Acidosis ◽

Mechanically Ventilated ◽

Mechanically Ventilated Patients ◽

Low Tidal Volume ◽

Volume Ventilation ◽

Low Volume ◽

Ventilated Patients

The use of lower tidal volume ventilation was shown to improve survival in mechanically ventilated patients with acute lung injury. In some patients this strategy may cause hypercapnic acidosis. A significant body of recent clinical data suggest that hypercapnic acidosis is associated with adverse clinical outcomes including increased hospital mortality. We aimed to review the available treatment options that may be used to manage acute hypercapnic acidosis that may be seen with low tidal volume ventilation. The databases of MEDLINE and EMBASE were searched. Studies including animals or tissues were excluded. We also searched bibliographic references of relevant studies, irrespective of study design with the intention of finding relevant studies to be included in this review. The possible options to treat hypercapnia included optimising the use of low tidal volume mechanical ventilation to enhance carbon dioxide elimination. These include techniques to reduce dead space ventilation, and physiological dead space, use of buffers, airway pressure release ventilation and prone positon ventilation. In patients where hypercapnic acidosis could not be managed with lung protective mechanical ventilation, extracorporeal techniques may be used. Newer, minimally invasive low volume venovenous extracorporeal devices are currently being investigated for managing hypercapnia associated with low and ultra-low volume mechanical ventilation.

Download Full-text

Respiratory impedances and acinar gas transfer in a canine model for emphysema

Journal of Applied Physiology ◽

10.1152/jappl.1997.83.1.179 ◽

1997 ◽

Vol 83 (1) ◽

pp. 179-188 ◽

Cited By ~ 8

Author(s):

George M. Barnas ◽

Paul A. Delaney ◽

Ileana Gheorghiu ◽

Srinivas Mandava ◽

Robert G. Russell ◽

...

Keyword(s):

Tidal Volume ◽

Chest Wall ◽

Canine Model ◽

Gas Transfer ◽

Secondary Complications ◽

Flow Measurements ◽

Mechanically Ventilated ◽

Tissue Sections ◽

Acinar Structure ◽

Blood Flow Measurements

Barnas, George M., Paul A. Delaney, Ileana Gheorghiu, Srinivas Mandava, Robert G. Russell, Renée Kahn, and Colin F. Mackenzie. Respiratory impedances and acinar gas transfer in a canine model for emphysema. J. Appl. Physiol. 83(1): 179–188, 1997.—We examined how the changes in the acini caused by emphysema affected gas transfer out of the acinus (Taci) and lung and chest wall mechanical properties. Measurements were taken from five dogs before and 3 mo after induction of severe bilateral emphysema by exposure to papain aerosol (170–350 mg/dose) for 4 consecutive wk. With the dogs anesthetized, paralyzed, and mechanically ventilated at 0.2 Hz and 20 ml/kg, we measured Taciby the rate of washout of133Xe from an area of the lung with occluded blood flow. Measurements were repeated at positive end-expiratory pressures (PEEP) of 10, 5, 15, 0, and 20 cmH2O. We also measured dynamic elastances and resistances of the lungs (El and Rl, respectively) and chest wall at the different PEEP and during sinusoidal forcing in the normal range of breathing frequency and tidal volume. After final measurements, tissue sections from five randomly selected areas of the lung each showed indications of emphysema. Taciduring emphysema was similar to that in control dogs. Eldecreased by ∼50% during emphysema ( P < 0.05) but did not change its dependence on frequency or tidal volume. Rl did not change ( P > 0.05) at the lowest frequency studied (0.2 Hz), but in some dogs it increased compared with control at the higher frequencies. Chest wall properties were not changed by emphysema ( P > 0.05). We suggest that although large changes in acinar structure and El occur during uncomplicated bilateral emphysema, secondary complications must be present to cause several of the characteristic dysfunctions seen in patients with emphysema.

Download Full-text

Vibrating Mesh Nebulisation of Pro-Antimicrobial Peptides for Use in Cystic Fibrosis

Pharmaceutics ◽

10.3390/pharmaceutics11050239 ◽

2019 ◽

Vol 11 (5) ◽

pp. 239 ◽

Cited By ~ 3

Author(s):

Éanna Forde ◽

Graeme Kelly ◽

Louise Sweeney ◽

Deirdre Fitzgerald-Hughes ◽

Ronan MacLoughlin ◽

...

Keyword(s):

Cystic Fibrosis ◽

Antimicrobial Peptides ◽

Droplet Size ◽

Droplet Size Distribution ◽

Antimicrobial Activities ◽

Physical Characteristics ◽

Mechanically Ventilated ◽

Delivery Times ◽

Before And After ◽

Spontaneously Breathing

Background: There has been considerable interest in the use of antimicrobial peptides (AMPs) as antimicrobial therapeutics in many conditions including cystic fibrosis (CF). The aim of this study is to determine if the prodrugs of AMPs (pro-AMPs) can be delivered to the lung by a vibrating mesh nebuliser (VMN) and whether the pro-AMP modification has any effect on delivery. Methods: Physical characteristics of the peptides (AMP and pro-AMP) and antimicrobial activity were compared before and after nebulisation. Droplet size distribution was determined by laser diffraction and cascade impaction. Delivery to a model lung was determined in models of spontaneously-breathing and mechanically-ventilated patients. Results: The physical characteristics and antimicrobial activities were unchanged after nebulisation. Mean droplet size diameters were below 5 μm in both determinations, with the fine particle fraction approximately 67% for both peptides. Approximately 25% of the nominal dose was delivered in the spontaneously-breathing model for both peptides, with higher deliveries observed in the mechanically-ventilated model. Delivery times were approximately 170 s per mL for both peptides and the residual volume in the nebuliser was below 10% in nearly all cases. Conclusions: These results demonstrate that the delivery of (pro-)AMPs to the lung using a VMN is feasible and that the prodrug modification is not detrimental. They support the further development of pro-AMPs as therapeutics in CF.

Download Full-text

A reproducible model of chronic hypoxemia

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.1983.244.5.h730 ◽

1983 ◽

Vol 244 (5) ◽

pp. H730-H733

Author(s):

H. G. Erath ◽

T. P. Graham ◽

J. W. Hammon ◽

H. W. Bender

Keyword(s):

Pulmonary Veins ◽

Vena Cava ◽

Prosthetic Graft ◽

Pulmonary Tissue ◽

Mechanically Ventilated ◽

Persistent Depression ◽

The Right ◽

Chronic Hypoxemia ◽

Breathing Room ◽

Spontaneously Breathing

This report presents our experience with producing a stable chronic hypoxemia preparation in the dog without the disadvantages of prosthetic graft insertion or sacrifice of pulmonary tissue. In 28 adult dogs, the intrapericardial inferior vena cava and the area of junction of the right and left inferior pulmonary veins were exposed through a right thoracotomy. The cava was clamped at the diaphragm and at the right atrium, divided at the atrial clamp, and quickly anastomosed to the inferior pulmonary veins. The mean arterial O2 tension (PaO2) decreased from 83.2 +/- 1.6 mmHg preoperatively in mechanically ventilated (room air) animals to 35.3 +/- 1.5 mmHg postoperatively in awake animals spontaneously breathing room air (P less than 0.001). There was persistent depression of the PaO2 (49.1 +/- 1.8 mmHg) and elevation of the hematocrit (64.8 +/- 2.0%) in six animals tested at 18.5 mo postoperatively. Shunt patency without significant stenosis was confirmed in each animal at autopsy. This method attains predictable and persistent hypoxemia and polycythemia and is simple to perform. It may be useful in studying various aspects of ventricular function and ventricular histological and biochemical changes with chronic cyanosis.

Download Full-text

Mechanical role of expiratory muscles during breathing in upright dogs

Journal of Applied Physiology ◽

10.1152/jappl.1988.64.3.1060 ◽

1988 ◽

Vol 64 (3) ◽

pp. 1060-1067 ◽

Cited By ~ 15

Author(s):

G. A. Farkas ◽

R. E. Baer ◽

M. Estenne ◽

A. De Troyer

Keyword(s):

Tidal Volume ◽

Progressive Increase ◽

Substantial Contribution ◽

Postural Changes ◽

Before And After ◽

Cervical Vagotomy ◽

Anesthetized Dogs ◽

Expiratory Muscles ◽

Spontaneously Breathing

To examine the mechanical effects of the abdominal and triangularis sterni expiratory recruitment that occurs when anesthetized dogs are tilted head up, we measured both before and after cervical vagotomy the end-expiratory length of the costal and crural diaphragmatic segments and the end-expiratory lung volume (FRC) in eight spontaneously breathing animals during postural changes from supine (0 degree) to 80 degrees head up. Tilting the animals from 0 degree to 80 degrees head up in both conditions was associated with a gradual decrease in end-expiratory costal and crural diaphragmatic length and with a progressive increase in FRC. All these changes, however, were considerably larger (P less than 0.005 or less) postvagotomy when the expiratory muscles were no longer recruited with tilting. Alterations in the elastic properties of the lung could not account for the effects of vagotomy on the postural changes. We conclude therefore that 1) by contracting during expiration, the canine expiratory muscles minimize the shortening of the diaphragm and the increase in FRC that the action of gravity would otherwise introduce, and 2) the end-expiratory diaphragmatic length and FRC in upright dogs are thus actively determined. The present data also indicate that by relaxing at end expiration, the expiratory muscles make a substantial contribution to tidal volume in upright dogs; in the 80 degrees head-up posture, this contribution would amount to approximately 60% of tidal volume.

Download Full-text