II. Background
- At rest
- Tidal Volume (TV) represents basal respiratory flow, in and out (similar to gentle ocean tides)
- With exertion
- Vital Capacity (IRV and ERV, in addition to TV) is recruited to allow for deeper breaths
- Analogous to Cardiac Stroke Volume, which increases with exertion
- May increase with Exercise from 500 ml to 4200 ml per breath (TV+IRV +ERV) in 70 kg adult
- In Obstructive Lung Disease (Asthma, COPD), taking deep breaths is primary compensation
- Increasing Tidal Volume with deep breaths is less work than increasing Respiratory Rate
- When Vital Capacity is insufficient to support exertion, Respiratory Rate (RR) increases
- Respiratory Rate is analogous to Heart Rate in compensation for exertion
- May increase with Exercise, from 12 to 36 breaths per minute with strenuous Exercise
- Increased Respiratory Rate is primary compensation in high lung elastic rebound
- Increasing Respiratory Rate is less energy for these patients, then taking deep breaths
- Minute Ventilation may increase with Exercise from 6 L/min to over 150 L/min
- Vital Capacity (IRV and ERV, in addition to TV) is recruited to allow for deeper breaths
- Images
III. Interpretation: Overall Lung Volumes
-
Vital Capacity (VC)
- Maximal volume expelled after maximal inspiration
- VC = ERV + TV + IRV
- VC = TLC - RV
- Decreased with low Lung Compliance, high elastic rebound (e.g. Restrictive Lung Disease, pulmonary fibrosis)
- Also low in Obstructive Lung Disease (e.g. Asthma, COPD), due to limited expiration (high Residual Volume)
- Total Lung Capacity (TLC)
- Volume in lungs at end of maximal inspiration
- Calculation: VC + RV
- Normal adult: 4-6 Liters
- Minute Ventilation (MV, Respiratory Minute Volume)
- Volume of breath inspired (and expired) per minute
- MV = TidalVolume x RespiratoryRate
- Typical resting Minute Ventilation in a 70 kg male is 6 liters/min = 500 ml TV x 12 breaths/min
- Alveolar Ventilation
- Volume of inspired air entering the alveoli per minute
- Similar to Minute Ventilation but subtracts alveolar dead space
- Aveolar dead space is 30-33% of Minute Ventilation in normal lungs (primarily Anatomic Dead Space)
- In a healthy lung, alveolar ventilation is typically two thirds of Minute Ventilation
- In very severe, end-stage COPD, alveolar ventilation may be as low as 20% of Minute Ventilation
- AV = (TidalVolume - AnatomicDeadSpace) x RespiratoryRate
- Normal adult example = (500-150) * 16 = 5600 ml
IV. Interpretation: Inspiratory Volumes
- Inspiratory Reserve Volume (IRV)
- Additional volume that could be inspired above normal inspiration (or Tidal Volume)
- Maximal inspired volume from end-tidal inspiration
- IRV may be as high as 40-43 ml/kg or 2800 ml in a 70 kg adult)
- Tidal Volume (Vt)
- Volume inspired and expired with each normal breath
- Tidal Volume is approximately one third of Vital Capacity
- Analogous to Cardiac Stroke Volume at Rest
- Minimum volume: 3 ml/kg
- Normal volume: 6-7 ml/kg (e.g. 500 ml in a 70 kg adult at rest)
- Typical ventilator Tidal Volume settings: 6-8 ml/kg
- Inspiratory Capacity (IC)
- Maximal volume inspired from resting expiratory level
- Calculation: IRV + Vt
V. Interpretation: Expiratory Volumes
- Expiratory Reserve Volume (ERV)
- Additional volume that could be expired in addition to normal exhalation (or Tidal Volume)
- Maximal expired volume from end-tidal inspiration
- Normal: 25% of Vital Capacity (up to 15 ml/kg or 1050 ml in a 70 kg adult)
-
Functional Residual Capacity (FRC)
- Volume remaining in lungs at resting expiratory level
- Resting position of the respiratory Muscles
- Balance between the opposing recoil forces of lung and chest wall
- Functional Residual Capacity (FRC) is a key point from which other Lung Volumes are measured
- Inspiratory Capacity (IC) is measured from FRC to Total Lung Capacity (TLC)
- Expiratory Reserve Volume (ERV) is measured from FRC to Residual Volume (RV)
- FRC Measurements
- Body Plethysmography or body box
- Based on Boyle's law (Product of Pressure and Volume is constant, at constant Temperature)
- Technique
- Initial pressures are measured at mouth and in airtight box at rest (volume = FRC)
- Patient pants against a closed shutter and pressures are re-measured
- Volume has decreased from FRC to Residual Volume
- Pressure has increased
- FRC = Patm x dPb/dPm
- Where Patm = atmospheric or barometric pressure
- Where dPb = change in airtight box pressure
- Where dPm = change in mouth pressure
- Nitrogen Washout
- Start by rest breathing with normal Tidal Volumes
- At, end expiration, inhaled gas changed from room air to 100% oxygen
- Total exhaled nitrogen is measured over subsequent exhalations
- Volume of gas required to contain expired nitrogen is calculated (air is 78% nitrogen)
- Helium Dilution in Closed Circuit
- Start by rest breathing with normal Tidal Volumes
- At, end expiration, inhaled gas changed from room air to 10% helium in air
- Breathing and measurements continue until measured helium concentration reaches steady state
- Expired Carbon dioxide is absorbed by soda lime
- Used oxygen is replaced in the inspired air
- Helium concentration before and after steady state are used to calculate volume of replaced gas
- Body Plethysmography or body box
- Forced Expiratory Volume in One Second (FEV1)
- Expiratory rate (FEV1) slowed by Obstructive Lung Disease (Asthma, COPD, chest masses)
- Residual Volume (RV)
- Volume remaining in lungs after maximal expiration
- Normal adult: 1.0 to 2.4 Liters
- Includes Respiratory Dead Space (anatomic and physiologic)
- Also includes healthy respiratory zone (alveoli to Bronchioles) that contribute to gas exchange
- Allows for passive CO2 and O2 diffusion in gas remaining in aveoli and Bronchioles between breaths
- Contrast with Physiologic Dead Space in diseased respiratory zone that cannot gas exchange
- RV is not measureable with standard Spirometry/PFTs
- Requires advanced testing (e.g. nitrogen washout, helium dilution, body plethysmography)
- Increased Residual Volume may also be suggested by barrel chest, hyperexpansion on CXR
VI. Interpretation: Dead Space
- Total Dead Space (Physiologic Dead Space)
- PhysiologicDeadSpace = AnatomicDeadSpace + AlveolarDeadSpace
- Anatomic Dead Space
- Volume of air within the nose, trachea and Bronchi that does not contribute to gas exchange
- Present in all patients regardless of health, representing 30-33% of Tidal Volume (e.g. 150 ml in 70 kg adult)
- Alveolar Dead Space
- Volume of air within the respiratory zone (alveoli to Bronchioles) that does not contribute to gas exchange
- In healthy patients, alveolar dead space is minimal (<5 ml)
- In diseased lung (e.g. COPD) or edematous lung (e.g. CHF, ARDS), alveolar dead space may be large
- Severe disease total dead space may be as large as 50-80% of Tidal Volume
- Ventilation-Perfusion mismatch results in some regions of lung that are over-ventilated and other underventilated
- Over-ventilated alveoli (V/Q>1) waste ventilation as blood is saturated with oxygen at a fixed maximum
- Alveolar dead space is the total excess ventilation to over-ventilated alveoli (V/Q>1)
- Measured Dead Space
VII. Resources
- Intagliata (2020) Lung Dead Space, StatPearls, Accessed 3/30/2021
VIII. References
- Rollings (1984) Facts and Formulas, McNaughton & Gunn
- Marini (1987) Respiratory Medicine, Williams & Wilkins
Images: Related links to external sites (from Bing)
Related Studies
Definition (NCI_CDISC) | The maximum volume of air a subject can exhale from the lungs after a tidal exhalation. |
Definition (NCI) | The maximum volume of air a subject can exhale from the lungs after a tidal exhalation. |
Definition (MSH) | The extra volume of air that can be expired with maximum effort beyond the level reached at the end of a normal, quiet expiration. Common abbreviation is ERV. |
Concepts | Laboratory or Test Result (T034) , Organ or Tissue Function (T042) |
MSH | D005105 |
SnomedCT | 55532004 |
English | Expiratory Reserve Volumes, Reserve Volume, Expiratory, Reserve Volumes, Expiratory, Volume, Expiratory Reserve, Volumes, Expiratory Reserve, expiratory reserve volume, ERV-Expiratory reserve volume, erv, expiratory reserve volume (ERV) of lung, ERV, Expiratory reserve volume, ERV - Expiratory reserve volume, Expiratory reserve volume (observable entity), Expiratory Reserve Volume |
Japanese | 予備呼気量, ヨビコキリョウ |
Swedish | Utandningsreservvolym |
Czech | ERV, exspirační rezervní objem, Exspirační rezervní objem |
Finnish | Uloshengityksen varatila |
French | Volume de réserve expiratoire, VRE (Volume de Réserve Expiratoire) |
Russian | VYDOKHA REZERVNYI OB"EM, ВЫДОХА РЕЗЕРВНЫЙ ОБЪЕМ |
Italian | Volume di riserva espiratoria |
Polish | Objętość wydechowa zapasowa |
Hungarian | Kilégzési tartalék térfogat |
Portuguese | Volume de Reserva Expiratória, Volume Expiratório de Reserva, Volume de reserva expiratória |
Spanish | Volumen de Reserva Espiratoria, Volumen Espiratorio de Reserva, VRE, volumen de reserva espiratorio (entidad observable), volumen de reserva espiratorio, Volumen espiratorio de reserva |
Norwegian | Utåndingsreservevolum, Ekspiratorisk reservevolum, ERV |
Dutch | expiratoir reservevolume, Reservevolume, respiratoir |
German | expiratorisches Reservevolumen, Exspiratorisches Reservevolumen |
Ontology: Inspiratory Capacity (C0021610)
Definition (CHV) | The maximum volume of air that can be inspired after reaching the end of a normal, quiet expiration |
Definition (NCI_CDISC) | The maximum volume of air a subject can inhale into the lungs after a tidal exhalation (IRV plus TV). |
Definition (NCI) | The maximum volume of air a subject can inhale into the lungs after a tidal exhalation (IRV plus TV). |
Definition (MSH) | The maximum volume of air that can be inspired after reaching the end of a normal, quiet expiration. It is the sum of the TIDAL VOLUME and the INSPIRATORY RESERVE VOLUME. Common abbreviation is IC. |
Concepts | Organism Attribute (T032) |
MSH | D007320 |
SnomedCT | 29533001 |
LNC | MTHU008904 |
English | Capacities, Inspiratory, Capacity, Inspiratory, Inspiratory Capacities, INSPIRATORY CAPAC, inspiratory capacity, Capacity.inspiratory, IC, Inspiratory capacity, IC - Inspiratory capacity, Inspiratory capacity (observable entity), Inspiratory Capacity |
Japanese | 深吸気量, シンキュウキリョウ |
Swedish | Inandningskapacitet |
Czech | inspirační kapacita, Inspirační kapacita |
Finnish | Sisäänhengityskapasiteetti |
French | Capacité vitale inspiratoire, CI (Capacité Inspiratoire), Capacité inspiratoire |
Russian | VDOKHA EMKOST', ВДОХА ЕМКОСТЬ |
Polish | Pojemność wdechowa, IC |
Hungarian | Belégzési kapacitás |
Norwegian | Inspiratorisk kapasitet |
Spanish | CI, capacidad inspiratoria (entidad observable), capacidad inspiratoria, Capacidad inspiratoria, Capacidad Inspiratoria |
Portuguese | Capacidade inspiratória, Capacidade Inspiratória |
Dutch | inspiratoire capaciteit, Capaciteit, inspiratoire, Inspiratoire capaciteit |
German | inspiratorische Kapazitaet, Inspirationskapazität, Kapazität, inspiratorische |
Italian | Capacità inspiratoria |
Ontology: Inspiratory Reserve Volume (C0021613)
Definition (NCI) | The maximum volume of air a subject can inhale into the lungs after a tidal inhalation. |
Definition (NCI_CDISC) | The maximum volume of air a subject can inhale into the lungs after a tidal inhalation. |
Definition (MSH) | The extra volume of air that can be inspired with maximal effort after reaching the end of a normal, quiet inspiration. Common abbreviation is IRV. |
Concepts | Laboratory or Test Result (T034) , Organ or Tissue Function (T042) |
MSH | D007321 |
SnomedCT | 55562005 |
English | Inspiratory Reserve Volume, Inspiratory Reserve Volumes, Reserve Volume, Inspiratory, Reserve Volumes, Inspiratory, Volume, Inspiratory Reserve, Volumes, Inspiratory Reserve, inspiratory reserve volume (IRV), inspiratory reserve volume, irv, IRV, Inspiratory reserve volume, IRV - Inspiratory reserve, Inspiratory reserve volume (observable entity) |
Swedish | Inandningsreservvolym |
Czech | inspirační rezervní objem, IRV |
Finnish | Sisäänhengityksen varatila |
French | Volume de réserve inspiratoire, VRI (Volume de Réserve Inspiratoire) |
Russian | VDOKHA REZERVNYI OB"EM, ВДОХА РЕЗЕРВНЫЙ ОБЪЕМ |
Polish | IRV, Objętość wdechowa zapasowa |
Portuguese | Volume de Reserva Inspiratória, Volume Inspiratório de Reserva |
Spanish | Volumen de Reserva Inspiratoria, Volumen Inspiratorio de Reserva, VRI, volumen de reserva inspiratoria (entidad observable), volumen de reserva inspiratoria |
Norwegian | Inspiratorisk reservevolum, IRV, Innåndingsreservevolum |
German | Inspiratorisches Reservevolumen |
Italian | Volume della riserva inspiratoria |
Dutch | Inspiratoir reservevolume, Reservevolume, inspiratoir |
Ontology: Respiratory Dead Space (C0035218)
Definition (MSH) | That part of the RESPIRATORY TRACT or the air within the respiratory tract that does not exchange OXYGEN and CARBON DIOXIDE with pulmonary capillary blood. |
Concepts | Organ or Tissue Function (T042) |
MSH | D012126 |
SnomedCT | 251916001 |
English | Dead Space, Respiratory, Dead Spaces, Respiratory, Respiratory Dead Space, Respiratory Dead Spaces, Space, Respiratory Dead, Spaces, Respiratory Dead, respiratory dead space, Respiratory dead space, VD - Dead space, Respiratory dead space (observable entity) |
Swedish | Andning, dead space |
Czech | dýchání - mrtvý prostor |
Finnish | Kuollut tila |
Russian | DYKHATEL'NOE MERTVOE PROSTRANSTVO, ДЫХАТЕЛЬНОЕ МЕРТВОЕ ПРОСТРАНСТВО |
Polish | Przestrzeń martwa |
Norwegian | Respiratorisk dødrom, Alveolært dødrom, Anatomisk dødrom, Fysiologisk alveolært dødrom |
Spanish | espacio muerto respiratorio (entidad observable), espacio muerto respiratorio, Espacio Muerto Respiratorio |
French | Espace mort respiratoire |
German | Respiratorischer Totraum |
Italian | Spazio morto respiratorio |
Dutch | Dode ruimte, Ruimte, dode |
Portuguese | Espaço Morto Respiratório |
Ontology: Tidal Volume (C0040210)
Definition (NCI) | The volume of air moved into and out of the lungs during breathing at rest. |
Definition (NCI_CDISC) | The volume of air moved into and out of the lungs during breathing at rest. |
Definition (MSH) | The volume of air inspired or expired during each normal, quiet respiratory cycle. Common abbreviations are TV or V with subscript T. |
Definition (CSP) | includes tidal volume, inspiratory and expiratory reserve volumes, residual volume, respiratory dead space, pulmonary ventilation, maximal voluntary ventilation, and vital capacity. |
Concepts | Finding (T033) |
MSH | D013990 |
SnomedCT | 13621006, 142202008, 165029006 |
LNC | LP75932-1 |
English | Tidal Volume, Tidal Volumes, Volume, Tidal, Volumes, Tidal, respiratory airway volume, VT, tidal volume, Lung tidal volume, Vt - Tidal volume, V T, V<sub>T</sub>, lungs tidal volume, tidal volumes, vts, v t, tidal volume (vt), t v, vt, TV, Tidal volume, TV - Tidal volume, VT - Tidal volume, Tidal volume (observable entity), V>T< |
Dutch | VT, Ademvolume, Volume, adem- |
French | TV, VT (Volume Courant), Volume courant |
German | VT, Atemhubvolumen, Atemzugvolumen |
Italian | Tachicardia ventricolare, Volume corrente |
Portuguese | Taquicardia ventricular, Volume de Ventilação Pulmonar |
Spanish | TV, volumen corriente pulmonar (entidad observable), volumen corriente pulmonar, Volumen de Ventilación Pulmonar |
Japanese | 心室性頻脈, シンシツセイヒンミャク |
Swedish | Andetagsvolym |
Czech | dechový objem, Komorová tachykardie |
Finnish | Kertahengitystilavuus |
Russian | DYKHATEL'NYI OB"EM, ДЫХАТЕЛЬНЫЙ ОБЪЕМ |
Polish | Objętość oddechowa, TV |
Hungarian | Kamrai tachycardia |
Norwegian | Tidalvolum, Respirasjonsvolum, Tidevolum |
Ontology: Total Lung Capacity (C0040509)
Definition (MSHCZE) | Objem vzduchu obsažený v plicích na konci maximálního vdechu. Je to ekvivalent každého z následujících termínů: VITÁLNÍ KAPACITA plus REZIDUÁLNÍ OBJEM PLIC; INSPIRAČNÍ KAPACITA plus FUNKČNÍ REZIDUÁLNÍ KAPACITA; DECHOVÝ OBJEM plus INSPIRAČNÍ REZERVNÍ OBJEM plus funkční reziduální kapacita; nebo dechový objem plus inspirační rezervní objem plus EXPIRAČNÍ REZERVNÍ OBJEM plus reziduální objem. |
Definition (NCI) | The total volume of air in the lungs after maximum inhalation. |
Definition (NCI_CDISC) | The total volume of air in the lungs after maximum inhalation. |
Definition (MSH) | The volume of air contained in the lungs at the end of a maximal inspiration. It is the equivalent to each of the following sums: VITAL CAPACITY plus RESIDUAL VOLUME; INSPIRATORY CAPACITY plus FUNCTIONAL RESIDUAL CAPACITY; TIDAL VOLUME plus INSPIRATORY RESERVE VOLUME plus functional residual capacity; or tidal volume plus inspiratory reserve volume plus EXPIRATORY RESERVE VOLUME plus residual volume. |
Concepts | Finding (T033) |
MSH | D014109 |
SnomedCT | 142205005, 57566009 |
English | Capacities, Total Lung, Capacity, Total Lung, Lung Capacities, Total, Lung Capacity, Total, Total Lung Capacities, Total Lung Capacity, TLC, TOTAL LUNG CAPAC, LUNG CAPAC TOTAL, total lung capacity (TLC), total lung capacity, tlc, Total lung capacity, TLC - Total lung capacity, Total lung capacity (observable entity), Maximum inflation |
Dutch | TLC, totale longcapaciteit, Longcapaciteit, totale |
French | CPT (capacité pulmonaire totale), CPT (Capacité Pulmonaire Totale), Capacité pulmonaire totale |
German | TLC, Totalkapazitaet der Lunge, Lungenkapazität, totale, Totale Lungenkapazität |
Japanese | TLC, ソウハイキリョウ, TLC, 全肺気量, 総肺容量, 総肺気量, 肺容量-総, 肺気量-全 |
Swedish | Total lungkapacitet |
Czech | plíce - celková kapacita, TLC, Celková plicní kapacita, celková kapacita plic |
Finnish | Keuhkojen kokonaistilavuus |
Russian | LEGKIKH EMKOST' OBSHCHAIA, ЛЕГКИХ ЕМКОСТЬ ОБЩАЯ |
Croatian | Not Translated[Total Lung Capacity] |
Polish | TLC, Pojemność płuc całkowita |
Hungarian | TLC, Teljes tüdő kapacitás |
Norwegian | Total lungekapasitet, Lungekapasitet, total |
Spanish | CPT, capacidad pulmonar total (entidad observable), capacidad pulmonar total, insuflación máxima, Capacidad pulmonar total, Capacidad Pulmonar Total |
Portuguese | Capacidade pulmonar total, Capacidade Pulmonar Total |
Italian | Capacità polmonare totale |
Ontology: Lung volume (C0231953)
Concepts | Organ or Tissue Function (T042) |
SnomedCT | 17785005 |
English | Lung volume, function, volume lung, lungs volume, lungs volumes, lung volumes, lung volume, Lung volume, Lung volume, function (observable entity), Lung volume, NOS, Lung volume (function) |
Spanish | volumen pulmonar (entidad observable), volumen pulmonar (función), volumen pulmonar |
Ontology: Anatomical dead space (C0231974)
Concepts | Finding (T033) |
SnomedCT | 89315003 |
English | VD(anat)-Anatomical dead space, Anatomic dead space, anatomical dead space, anatomic dead space, Anatomical dead space, VD(anat) - Anatomical dead space, Anatomical dead space (observable entity), Anatomic dead space, NOS, Conducting airways |
Spanish | espacio muerto anatómico (entidad observable), espacio muerto anatómico, vía aérea de conducción, vía aéreas conductoras |
Ontology: Physiological dead space (C0231975)
Concepts | Laboratory or Test Result (T034) |
SnomedCT | 88265002 |
English | VD(physiol)-Physiol dead space, Physiological dead space, VD(physiol) - Physiological dead space, Physiological dead space (observable entity) |
Spanish | espacio muerto fisiológico (entidad observable), espacio muerto fisiológico |
Ontology: Lung residual volume measurement (C0429713)
Concepts | Laboratory Procedure (T059) |
SnomedCT | 127803005 |
English | residual volume, residual (lung) volume, Lung residual volume measurement (procedure), Lung residual volume measurement |
Spanish | medición del volumen pulmonar residual (procedimiento), medición del volumen pulmonar residual |
Ontology: Minute ventilation (C1301655)
Concepts | Finding (T033) |
SnomedCT | 397802005 |
English | minute ventilation, Minute ventilation (finding), Minute ventilation |
Spanish | ventilación minuto (hallazgo), ventilación minuto |