Paper 3 Answers
James Day, Amy Thomson, Tamsin McAllister, Nawal Bahal in Get Through, 2014
There are a number of lung volumes that represent how much air is present in the lungs at different points in the breathing cycle. Lung capacities are the sum of a number of different lung volumes. All lung volumes can be measured by a simple spirometer except the residual volume (RV) and hence the functional residual capacity (FRC), the sum of the RV and the expiratory reserve volume. To measure the RV and hence the FRC we can use either the helium dilution technique or a body plethysmograph. The dilution technique works when using helium because it is almost insoluble in blood. A drawback of this technique is that the helium can only be diluted in the air in the lungs that can be ventilated. If there is significant air trapping then the helium will not be diluted in these portions. Hence this technique is not very accurate in those patients with obstructive airway diseases. A more accurate technique in these cases is to use the body plethysmograph, which utilizes Boyle’s law to calculate the lung volume by detecting a pressure change in an airtight box. When using the helium technique the patient is connected to the spirometer at the end of a normal breath to ensure the FRC is being measured and not other lung volumes.
Anatomy overview
Stephanie Martin in Working with Voice Disorders, 2020
The four lung volumes are as follows: Tidal Volume (TV) is the amount of air inspired or expired during a respiratory cycle at rest.Inspiratory Reserve Volume (IRV) is the maximum amount of air that can be taken into the lungs beyond the end of tidal inspiration.Expiratory Reserve Volume (ERV) is the greatest volume of air that can be expired at the end of spontaneous expiration.Residual Volume (RV) is the amount of air that remains in the lungs and airways at the end of maximal expiration.
SBA Answers and Explanations
Vivian A. Elwell, Jonathan M. Fishman, Rajat Chowdhury in SBAs for the MRCS Part A, 2018
The 4 lung volumes are: Tidal volume = volume of air inspired or expired with each normal breath in quiet breathing; approximately 500 mLResidual volume = volume of air that remains in the lung after forced expirationInspiratory reserve volume = extra volume of air that can be inspired over and above the normal tidal volumeExpiratory reserve volume = extra volume of air that can be expired by forceful expiration after the end of a normal tidal expiration
Driving pressure-guided ventilation versus protective lung ventilation in ARDS patients: A prospective randomized controlled study
Published in Egyptian Journal of Anaesthesia, 2021
Khaled M. Hamama, Sameh M. Fathy, Reda S. AbdAlrahman, Salah El-Din I. Alsherif, Sameh Abdelkhalik Ahmed
The beneficial effects of DP-guided ventilation compared to PLV in patients with ARDS can be explained by the heterogeneous distribution of lung pathology in ARDS [17]. The non-aerated units of the lung are responsible for the reduction in C stat [18], which reflects the end-expiratory lung volume. In turn, the tidal volume/end-expiratory lung volume ratio represents lung strain. Therefore, this ratio, also called DP, can be considered a substitute for lung strain. Use of tidal volume according to PBW in PLV strategy exposes the lungs to the forces of cyclic stretch and inflation that release inflammatory mediators to the systemic circulation, which in turn have a negative impact on organ/s function. On the other hand, in DP-guided ventilation, manipulation of tidal volume tailored to the size of the aerated lung, which prevents cyclic or dynamic strain of the lung [19].
Risk factors for impaired pulmonary function and cardiorespiratory fitness in very long-term adult survivors of childhood acute lymphoblastic leukemia after treatment with chemotherapy only*
Published in Acta Oncologica, 2018
Ole Henrik Myrdal, Adriani Kanellopoulos, Jon R. Christensen, Ellen Ruud, Elisabeth Edvardsen, Johny Kongerud, Liv Ingunn Sikkeland, May B. Lund
Pulmonary function tests included dynamic spirometry, determination of static lung volumes and single breath gas diffusing capacity (DLCO). Spirometric variables were forced vital capacity (FVC), forced expiratory volume in 1 s (FEV1) and the ratio FEV1/FVC. Lung volume variables were total lung volume (TLC) and residual volume (RV). Gas transfer variables were transfer factor for carbon monoxide, DLCO and DLCO divided by alveolar volume, VA. DLCO measurements were also corrected for Hb. All measurements were performed with the Vmax Pulmonary Function Unit (VIASYS Respiratory Care Inc, Yorba Linda, CA) and according to the guidelines recommended by the European Respiratory Society guidelines (ERS) [26–28]. The pulmonary function variables were expressed in absolute values and as a percentage of predicted normal values. Reference values were those recommended by ERS [29]. Obstructive impairment was defined as FEV1/FVC <0.7 according to The Global Initiative for Chronic Obstructive Lung Disease [30]. Restrictive impairment and impairment in DLCO were defined as <80% of predicted. These cutoff points correspond to the lower 5th percentiles in the reference material and in line with ERS recommendations [29].
Acute pulmonary and splenic response in an in vivo model of whole-body low-dose X-radiation exposure
Published in International Journal of Radiation Biology, 2019
Stephanie Puukila, Stacy Muise, James McEvoy, Tara Bouchier, Antony M. Hooker, Douglas R. Boreham, Neelam Khaper, Dani-Louise Dixon
Following the start of ventilation, rats were paralyzed by i.p. injection of pancuronium bromide (1 mL) to prevent spontaneous breathing during respiratory mechanics measurements. Prior to the measurement of lung mechanics, a single sigh breath of 2.5x tidal volume (20 mL/kg) and 2 cmH2O PEEP held for 6 seconds was delivered to normalize lung volume history. This was immediately followed by forced oscillation of 16 seconds of interrupted ventilation consisting of 19 sine waves with multiple prime frequencies (0.25 to 19.125 Hz) and a peak-to-peak volume excursion of 1.0 mL above the end-expiratory lung volume. The data were fitted to the constant phase model: aw is airway resistance, Gtis is tissue resistance, Htis is tissue elastance, I is inertance, j is the imaginary unit, f is frequency of the oscillation and α=(2/π)arc tan (Htis/Gtis) (Hantos et al. 1992).
Related Knowledge Centers
- Altitude Sickness
- Breathing
- Lung
- Tidal Volume
- Spirometer
- Respiratory Rate
- Functional Residual Capacity
- Thoracic Diaphragm
- Minute Ventilation
- Pulmonary Function Testing