Normal ventilator values you look up at 2 a.m.
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Normal ventilator values are the ranges a patient usually sits in: adult, mechanically ventilated, nothing acute in progress. Tidal volume, airway pressures, EtCO2, ABG and VBG numbers, the RASS score you report at handoff, all of it belongs on one card instead of six different textbooks. This page is that card, adult only, every value carrying the source it came from.
A normal range is where most patients land, not an order for the one on your stretcher. The disease process, the airway, and the protocol you work under move the target from there, and no chart can see any of that. What follows is a fast lookup, sourced end to end, for the numbers you check the range against.
Jump to:
- Normal ventilator values at a glance
- What a high or low value is telling you
- Airway pressures: peak, plateau, and cuff
- Volume and rate: tidal volume, minute ventilation, and set rate
- Oxygenation: FiO2, PEEP, and SpO2 targets
- Blood gas reference: ABG and VBG ranges
- Capnography: normal EtCO2 and the PaCO2 gap
- Sedation scoring: the RASS scale
- Common questions about normal ventilator values
Normal ventilator values at a glance
Twelve numbers, adult patients only, each one attributed to the source it actually came from instead of blended into a single house range.
| Parameter | Normal adult range | Source |
|---|---|---|
| Tidal volume (Vt) | 6 mL/kg IBW target; 4-8 mL/kg working range | ARDS Network (ARMA trial), NEJM 2000;342(18):1301-1308 (6 mL/kg target); StatPearls, Mechanical Ventilation, NBK539742 (4-8 mL/kg range) |
| Respiratory rate (RR) | 12-20/min is the normal adult resting rate, not a vent setting. Typical set rate on the ventilator runs 12-16/min | StatPearls, Physiology, Respiratory Rate, NBK537306 (resting rate); StatPearls, Mechanical Ventilation, NBK539742 (set rate) |
| Minute ventilation (Ve) | Ve = Vt x RR. No single normal L/min figure worth memorizing | StatPearls, Physiology, Tidal Volume, NBK482502 |
| PEEP | 5 cm H2O to start, enough to overcome the ventilator circuit’s own resistance; higher than 10 cm H2O in ARDS | StatPearls, EMS Portable Ventilator Management, NBK537072 |
| FiO2 | 100% is the common default immediately after intubation, then titrated down to the minimum that holds SpO2 in target range; prolonged exposure risks hyperoxemia | StatPearls, EMS Portable Ventilator Management, NBK537072 |
| Peak inspiratory pressure (Ppeak) | Usually kept below 40 cm H2O | StatPearls, Ventilator Safety, NBK526044 |
| Plateau pressure (Pplat) | Under 30 cm H2O | StatPearls NBK526044; NHLBI ARDS Clinical Network protocol card |
| I:E ratio | 1:2 to 1:3 with normal lung mechanics, extending to 1:4 or longer in obstructive disease | StatPearls NBK539742 and Merck Manual Professional Edition |
| ETT cuff pressure | 20-30 cm H2O | Jaillette E et al., Annals of Intensive Care. 2014;4:7 |
| EtCO2 | 35-45 mmHg | StatPearls, Capnography, NBK539754 |
| SpO2 | 94-98% for acutely ill adults not at risk of hypercapnic respiratory failure; 88-95% is the ARDS/lung-protective goal for mechanically ventilated patients | BTS guideline for oxygen use in adults, Thorax. 2017;72(Suppl 1) (94-98% band); NHLBI ARDS Clinical Network protocol card (88-95% goal) |
| Arterial pH | 7.35-7.45 | StatPearls, Arterial Blood Gas Analysis, NBK536919 |
What a high or low value is telling you
| Parameter | If it is high | If it is low | Source |
|---|---|---|---|
| Peak pressure (Ppeak) | With a normal plateau: a resistance problem, secretions, bronchospasm, a kinked or bitten tube, water in the circuit. With plateau also elevated: a compliance problem, pneumothorax, atelectasis, pulmonary edema, abdominal compartment syndrome | Not a standalone finding | StatPearls, Ventilator Safety, NBK526044 |
| Plateau pressure (Pplat) | Reduce tidal volume toward 6 mL/kg IBW, consider sedation to improve compliance, look for a compliance problem (pneumothorax, atelectasis, pulmonary edema, ARDS), consider gastric decompression | Not clinically actionable; the ceiling is the point, not a floor | StatPearls NBK526044; NHLBI ARDS Clinical Network protocol card |
| EtCO2 | If hypoventilation, increase minute ventilation, usually a higher rate with tidal volume held at its lung-protective target. In obstructive disease or auto-PEEP, lengthen expiratory time instead of reflexively raising the rate. | Check the waveform and tube position first, since capnography is the confirmation standard for placement. If over-ventilation, lower the rate. Consider reduced cardiac output, shock, or PE, where falling pulmonary perfusion and rising dead space drop the number | StatPearls NBK539754 (range, hypo- and hyperventilation patterns); Aminiahidashti H et al., Emergency (Tehran). 2018;6(1):e5 (shock, PE, tube confirmation); StatPearls NBK526044 (auto-PEEP) |
| SpO2 | Sustained above target: wean FiO2 down to the minimum that holds the target. Avoid sustained hyperoxia | Raise FiO2 and consider PEEP for recruitment. Do not withhold high FiO2 from a hypoxic or freshly intubated patient | BTS guideline, Thorax 2017; StatPearls NBK537072; NHLBI ARDS Clinical Network protocol card |
| PEEP | Rising plateau pressure and hemodynamic compromise: the added intrathoracic pressure cuts the gradient to the vena cava and drops cardiac preload. In obstructive disease, watch for auto-PEEP from breath stacking, expiratory flow that never returns to baseline on the waveform | Poor oxygenation despite adequate FiO2: PEEP prevents alveolar collapse and widens the diffusion gradient for oxygen, so consider raising it while watching plateau pressure and blood pressure | StatPearls NBK537072 (preload, recruitment); StatPearls NBK526044 (auto-PEEP) |
| Tidal volume | Above 8 mL/kg IBW risks lung injury | Fails to clear CO2, showing up as a rising EtCO2 or PaCO2 | StatPearls NBK537072; StatPearls NBK539742; ARDS Network NEJM 2000 |
| Respiratory rate | Shortens expiratory time, risking air trapping and auto-PEEP, especially in COPD or asthma; the fix is a lower rate or tidal volume, not more rate | Leaves minute ventilation short, showing up as a rising EtCO2 and PaCO2 | StatPearls NBK539742; StatPearls NBK526044 (auto-PEEP in asthma and COPD) |
| Cuff pressure | Above 30 cm H2O risks tracheal mucosal ischemia; deflate toward target, and check for tube size mismatch or tracheal pathology if it stays high | Below 20 cm H2O risks aspiration and air leak; re-inflate and reassess, and consider a cuff leak or tube exchange if pressure can’t be held | Jaillette E et al., Annals of Intensive Care. 2014;4:7 |
Airway pressures: peak, plateau, and cuff
Peak and plateau pressure get read together, not separately. Peak inspiratory pressure is usually kept below 40 cm H2O, per StatPearls’ ventilator-safety chapter, and it moves with airway resistance. Plateau pressure carries the firmer ceiling: under 30 cm H2O, measured with a brief inspiratory pause.
Three failure patterns show up at the head of the bed:
- Peak rises, plateau stays normal: a resistance problem, secretions, bronchospasm, a kinked or bitten tube, water in the circuit.
- Both rise together: a compliance problem, pneumothorax, atelectasis, pulmonary edema, a stiff abdomen.
- Cuff pressure runs outside 20-30 cm H2O: below risks aspiration and leak, above risks tracheal injury.
When one of these numbers crosses a limit and the vent starts alarming about it, the order that finds the cause fastest is its own subject: what to do when ventilator alarms fire.
What the peak-to-plateau gap tells you
Peak inspiratory pressure reflects airway resistance plus lung and chest wall compliance together; plateau pressure, measured with the breath held, reflects compliance alone, the split StatPearls’ ventilator-safety chapter describes. Subtracting one from the other isolates the resistance component, without a fixed cutoff attached to it here. A meaningful gap between the two points at resistance: something narrowing the airway or the tube. A gap that stays small, with plateau doing all the rising, points at compliance: something stiffening the lungs or the chest wall. Read the two curves together, since either number alone tells half the story.
Volume and rate: tidal volume, minute ventilation, and set rate
Tidal volume comes off ideal body weight, not the number on the scale: 6 mL/kg IBW is the lung-protective target from the ARDSNet ARMA trial, with 4-8 mL/kg the working range StatPearls describes. Minute ventilation, Ve = Vt x RR, has no single normal L/min figure worth memorizing; the app instead sets a minute-ventilation target first, IBW divided by 10 L/min, and derives the rate from that, rather than picking a rate off a chart. The rate is an output here, not an input. The physiologic resting rate for an adult breathing on their own, 12-20 per minute, is a different number entirely and does not belong in this math. For the full sequence and worked math, see how these ventilator settings get chosen and the tidal volume calculator math.
Oxygenation: FiO2, PEEP, and SpO2 targets
Two different SpO2 targets exist for two different clinical pictures, and your protocol decides which applies. The BTS oxygen-use guideline puts 94-98% on acutely ill adults who are not at risk of hypercapnic respiratory failure. For the lung-protective ARDS case specifically, the NIH ARDS Network protocol card sets a lower goal, SpO2 88-95%, paired with PaO2 55-80 mmHg. That 88-95% figure is a ventilated-patient oxygenation goal, not a general oxygen-therapy target.
FiO2 most often defaults to 100% right after intubation, then comes down to the minimum that holds the SpO2 target. StatPearls’ EMS ventilator chapter is blunt about why the weaning matters: prolonged exposure leads to hyperoxemia, which carries its own long-term harm.
PEEP starts at 5 cm H2O, enough to overcome the ventilator circuit’s own resistance in most adults, then titrates to oxygenation and blood pressure together. In ARDS it typically goes above 10 cm H2O.
Blood gas reference: ABG and VBG ranges
An arterial blood gas is the reference standard; a venous sample can stand in for some of it and not all of it. pH transfers well, arterial running about 0.03 higher than venous. Bicarbonate transfers well too. PaCO2 and PaO2 do not: the agreement is too wide, and a venous PO2 answers nothing about oxygenation. The table below states the arterial range first, then what the venous sample does to that number, with each direction carrying its own source rather than one blended figure.
| Analyte | Arterial normal | What a peripheral venous sample does to it | Source |
|---|---|---|---|
| pH | 7.35-7.45 | Tracks closely; arterial typically 0.03 higher (95% CI 0.029-0.038) | StatPearls NBK536919 (arterial); Byrne AL et al., Respirology. 2014;19(2):168-175 (venous offset) |
| PaCO2 | 35-45 mmHg | Not substitutable; the 95% prediction interval on the bias runs -10.7 to +2.4 mmHg | StatPearls NBK536919 (arterial); Byrne 2014 (venous) |
| HCO3 | 22-26 mEq/L | Agrees closely; average difference 1.20 mmol/L (95% limits of agreement -2.73 to +5.13 mmol/L) | StatPearls NBK536919 (arterial); Kelly AM et al., Emergency Medicine Australasia. 2004;16(5-6):407-409 (venous) |
| Base excess | -2 to +2 mmol/L (equivalent to mEq/L) | Not established from a source cited here | StatPearls, Adjusting Ventilator Settings Based on ABG Results, NBK606131 |
| PaO2 | 80-100 mmHg in a healthy adult at sea level; the lower limit falls with age and altitude, and some references cite 75-100 mmHg | Does not answer oxygenation; arterial typically 36.9 mmHg greater than venous (95% CI 27.2-46.6 mmHg) | StatPearls NBK606131; Trulock EP, Clinical Methods, 3rd ed., NBK371 (age and altitude); Byrne 2014 (venous) |
| SaO2 | 95-100% | Not established from a source cited here | StatPearls NBK536919 |
How VBG values differ from ABG
Byrne and colleagues’ 2014 systematic review and meta-analysis, eighteen studies and 1,768 subjects, found pH tracked closely, arterial about 0.03 higher than venous (95% confidence interval 0.029-0.038). PCO2 did not: the 95% prediction interval on the bias ran from -10.7 to +2.4 mmHg, too wide for a venous number to substitute for an arterial one. Venous PO2 answered nothing about oxygenation at all. Their own conclusion states it plainly: pH compares well between the two samples, PCO2 and PO2 do not, and the differences are large enough to be clinically significant. That supports screening pH and bicarbonate off a VBG, and confirming CO2 and oxygenation with an arterial sample or waveform capnography when the number actually changes a decision, within whatever your protocol allows.
Capnography: normal EtCO2 and the PaCO2 gap
Normal EtCO2 is 35-45 mmHg, per StatPearls’ capnography chapter, and it runs a little behind PaCO2 rather than matching it: in otherwise healthy people under anesthesia the gap commonly runs 2-5 mmHg, EtCO2 the lower number, per Doppmann and colleagues in Scientific Reports 2021. Capnography measures ventilation, not oxygenation, per the same chapter. Doppmann’s group put the limitation plainly: EtCO2 ran significantly lower than PaCO2, making it an unreliable proxy when the goal is normocapnic ventilation, and they describe the gap as multifactorial, driven by ventilation-perfusion mismatch, increased dead space, and shock with impaired perfusion. Those are the patients in whom confirming with an ABG or VBG matters most.
A rising EtCO2 from hypoventilation usually calls for more minute ventilation, typically a higher rate with tidal volume held at its lung-protective target. In obstructive disease or auto-PEEP, that instinct runs backward: lengthen expiratory time instead of reflexively raising the rate. Reading capnography waveforms, and what a rising EtCO2 is telling you, both have their own deeper reference on this site.
Sedation scoring: the RASS scale
RASS scores agitation and sedation on one scale, +4 combative through -5 unarousable, and it’s the number that travels at handoff because it says more in one digit than “sedated” or “agitated” ever could. The scale below states the scale itself, not a target; what the number should be depends on the clinical window, covered after the table.
| Score | Term | What you see |
|---|---|---|
| +4 | Combative | Overtly combative or violent; immediate danger to staff |
| +3 | Very agitated | Pulls at or removes tube(s) or catheter(s), or is aggressive toward staff |
| +2 | Agitated | Frequent non-purposeful movement, or fights the ventilator |
| +1 | Restless | Anxious or apprehensive, but movements are not aggressive or vigorous |
| 0 | Alert and calm | Spontaneously pays attention to the person at the bedside |
| -1 | Drowsy | Not fully alert, but has sustained awakening (more than 10 seconds), with eye contact, to voice |
| -2 | Light sedation | Briefly awakens (less than 10 seconds), with eye contact, to voice |
| -3 | Moderate sedation | Any movement, but no eye contact, to voice |
| -4 | Deep sedation | No response to voice, but any movement to physical stimulation |
| -5 | Unarousable | No response to voice or physical stimulation |
Source: Sessler CN et al., American Journal of Respiratory and Critical Care Medicine. 2002;166(10):1338-1344; Ely EW et al., JAMA. 2003;289(22):2983-2991, validated in mechanically ventilated adults.
What RASS score to target after intubation
The scale itself makes no recommendation; what differs is the clinical question being asked. PADIS 2018, the Society of Critical Care Medicine’s ICU guideline, suggests light sedation over deep sedation in critically ill mechanically ventilated adults, a conditional recommendation resting on low-quality evidence and aimed at sustained ICU ventilation measured in days.
The app’s reference screen is built for a different window, post-intubation transport measured in minutes to hours, and states a goal of RASS -2 to -4 for mechanically ventilated patients. Sedation practice in that window commonly runs deeper, toward that -4, deep sedation on the scale above, for tube security and patient comfort during movement. Neither target is wrong; they answer different questions for different windows of care. What applies to your patient is set by local protocol and medical direction, and it differs by service and by setting.
Common questions about normal ventilator values
What is a normal minute ventilation on a ventilator?
There isn’t one fixed number worth memorizing. Minute ventilation is tidal volume times respiratory rate, Ve = Vt x RR, and it moves with both inputs rather than sitting at a single normal figure the way plateau pressure does. The app sets a target instead: IBW divided by 10 L/min for a typical adult, higher in metabolic acidosis, then derives the rate from that target.
What is a normal EtCO2 on a ventilator?
35-45 mmHg, monitored continuously by waveform capnography rather than checked once. It tracks a little below PaCO2 in a healthy adult under anesthesia, commonly by 2-5 mmHg per Doppmann 2021, and reads best as a trend. A high EtCO2 usually means more minute ventilation is needed; in obstructive disease or auto-PEEP, lengthen expiratory time instead of reflexively raising the rate.
What are normal ABG values, and how does a VBG differ?
Arterial pH runs 7.35-7.45, PaCO2 35-45 mmHg, HCO3 22-26 mEq/L, PaO2 80-100 mmHg in a healthy adult at sea level, base excess -2 to +2 mmol/L. A venous sample tracks pH and bicarbonate closely enough to be useful. It does not track PaCO2 closely enough to substitute for it, and a venous PO2 says nothing about oxygenation at all.
What RASS score is normal after intubation?
There is no single normal number; the scale runs 0 for alert and calm through the sedation levels below zero. The literature and the app’s own reference describe different targets for different windows, sustained ICU ventilation versus short-window transport sedation, and neither is wrong for its setting. Local protocol and medical direction decide what your patient’s target actually is.
Keep the reference card in your pocket
The reference sets on this page have matching screens inside Rapid Vent Calculator: normal ventilator values, ABG and VBG ranges, and the RASS scale, all offline, all one tap from the numbers the app already calculated for this patient. The app carries the reference. It does not carry the decision. It cannot see the airway in front of you, does not know your agency’s protocol, and has no opinion about which target applies tonight. What it removes is the search, six textbooks and a laminated card replaced by the same values in your pocket, sourced the same way this page sources them. The vent calculator that runs these numbers is free on iPhone and Android.
Sources
- The Acute Respiratory Distress Syndrome Network (Brower RG et al). Ventilation with lower tidal volumes as compared with traditional tidal volumes for acute lung injury and the acute respiratory distress syndrome. New England Journal of Medicine. 2000;342(18):1301-1308. https://pubmed.ncbi.nlm.nih.gov/10793162/
- NHLBI ARDS Clinical Network. Mechanical Ventilation Protocol Summary (ventilator protocol card).
- StatPearls. Mechanical Ventilation. https://www.ncbi.nlm.nih.gov/books/NBK539742/
- StatPearls. EMS Portable Ventilator Management. https://www.ncbi.nlm.nih.gov/books/NBK537072/
- StatPearls. Physiology, Respiratory Rate. https://www.ncbi.nlm.nih.gov/books/NBK537306/
- StatPearls. Physiology, Tidal Volume. https://www.ncbi.nlm.nih.gov/books/NBK482502/
- StatPearls. Ventilator Safety. https://www.ncbi.nlm.nih.gov/books/NBK526044/
- Merck Manual Professional Edition. Overview of Mechanical Ventilation. https://www.merckmanuals.com/professional/critical-care-medicine/respiratory-failure-and-mechanical-ventilation/overview-of-mechanical-ventilation
- Jaillette E, Martin-Loeches I, Artigas A, Nseir S. Optimal care and design of the tracheal cuff in the critically ill patient. Annals of Intensive Care. 2014;4:7. https://pmc.ncbi.nlm.nih.gov/articles/PMC3941480/
- StatPearls. Capnography. https://www.ncbi.nlm.nih.gov/books/NBK539754/
- Aminiahidashti H, Shafiee S, Zamani Kiasari A, Sazgar M. Applications of end-tidal carbon dioxide (ETCO2) monitoring in emergency department: a narrative review. Emergency (Tehran). 2018;6(1):e5. https://pmc.ncbi.nlm.nih.gov/articles/PMC5827051/
- O’Driscoll BR, Howard LS, Earis J, Mak V. BTS guideline for oxygen use in adults in healthcare and emergency settings. Thorax. 2017;72(Suppl 1):ii1-ii90. https://www.brit-thoracic.org.uk/clinical-resources/guidelines/emergency-oxygen/
- StatPearls. Arterial Blood Gas Analysis. https://www.ncbi.nlm.nih.gov/books/NBK536919/
- Byrne AL, Bennett M, Chatterji R, Symons R, Pace NL, Thomas PS. Peripheral venous and arterial blood gas analysis in adults: are they comparable? A systematic review and meta-analysis. Respirology. 2014;19(2):168-175. https://pubmed.ncbi.nlm.nih.gov/24383789/
- Kelly AM, McAlpine R, Kyle E. Agreement between bicarbonate measured on arterial and venous blood gases. Emergency Medicine Australasia. 2004;16(5-6):407-409. https://pubmed.ncbi.nlm.nih.gov/15537402/
- Hassan W, Elkhatieb M. Adjusting Ventilator Settings Based on ABG Results. StatPearls. https://www.ncbi.nlm.nih.gov/books/NBK606131/
- Trulock EP III. Arterial Blood Gases. Chapter 49 in Walker HK, Hall WD, Hurst JW, eds. Clinical Methods. 3rd ed. Butterworths; 1990. https://www.ncbi.nlm.nih.gov/books/NBK371/
- Doppmann P, Meuli L, Sollid SJM, et al. End-tidal to arterial carbon dioxide gradient is associated with increased mortality in patients with traumatic brain injury: a retrospective observational study. Scientific Reports. 2021;11:10391. https://pmc.ncbi.nlm.nih.gov/articles/PMC8129079/
- Sessler CN, Gosnell MS, Grap MJ, et al. The Richmond Agitation-Sedation Scale: validity and reliability in adult intensive care unit patients. American Journal of Respiratory and Critical Care Medicine. 2002;166(10):1338-1344. https://pubmed.ncbi.nlm.nih.gov/12421743/
- Ely EW, Truman B, Shintani A, et al. Monitoring sedation status over time in ICU patients: reliability and validity of the Richmond Agitation-Sedation Scale (RASS). JAMA. 2003;289(22):2983-2991. https://pubmed.ncbi.nlm.nih.gov/12799407/
- Devlin JW, Skrobik Y, Gelinas C, et al. Clinical practice guidelines for the prevention and management of pain, agitation/sedation, delirium, immobility, and sleep disruption in adult patients in the ICU. Critical Care Medicine. 2018;46(9):e825-e873.
