IPAP, EPAP and Pressure Support: What the Numbers on Your BiPAP Prescription Actually Mean

It is 9 PM. You are standing in a hospital corridor in Safdarjung Enclave holding a discharge summary, and somewhere in the middle of it, between the medicine list and the follow-up date, is a line that looks like this:

BiPAP ST — IPAP 16 / EPAP 6 / BUR 12

The doctor has moved on to the next bed. The nurse says, "Arrange the machine tonight." And you are staring at three numbers that will decide how your father breathes for the next several months, with absolutely no idea what they mean.

This guide fixes that. By the end of it, you will be able to read that line the way a respiratory therapist reads it — what each number does inside the lungs, whether yours look typical for the condition, which ones matter most, and what to do when something feels wrong.

One thing before we start, and it matters more than anything else in this article: these numbers are set by your doctor after testing, and only your doctor should change them. Everything here is to help you understand and communicate — never to adjust.

The 20-second answer

IPAP is the higher pressure your BiPAP machine delivers when you breathe in. EPAP is the lower pressure it holds when you breathe out.

Pressure Support is the gap between them (IPAP minus EPAP) — it is the actual "push" that fills your lungs.

In simple terms: EPAP keeps your airway open, IPAP helps you take a bigger breath, and the difference between the two decides how much carbon dioxide you clear.

Number	Full form	When it acts	What it fixes	Typical home range
EPAP	Expiratory Positive Airway Pressure	Breathing out	Collapsing airway, low oxygen	4–10 cmH₂O
IPAP	Inspiratory Positive Airway Pressure	Breathing in	Shallow breaths, high CO₂	8–25 cmH₂O
PS (Δ)	Pressure Support/delta pressure	The difference	Ventilation, CO₂ clearance	4–14 cmH₂O

All three are measured in cmH₂O — centimetres of water pressure. It is a small unit. A pressure of 16 cmH₂O is roughly the pressure at the bottom of a 16-centimetre-deep glass of water. Gentle, but relentless, thirty thousand times a night.

EPAP: the number that holds the door open

Think of your upper airway as a soft rubber tube. When you fall asleep, the muscles holding it open relax. In obstructive sleep apnoea, that tube collapses — sometimes partly, sometimes completely — and airflow stops until your brain panics you awake enough to reopen it. Fifty times an hour. Every hour.

EPAP is the constant back-pressure that stops that collapse. It never drops to zero. Even at the very end of your exhale, there is a cushion of air sitting in your airway keeping it splinted open.

If you have used a CPAP machine before, EPAP is essentially the same thing as your CPAP pressure. (This is exactly why people who switch from CPAP often find their EPAP set close to their old CPAP number — see our guide on CPAP vs BiPAP vs APAP.)

EPAP does a second job that most patients never hear about. In hospital ventilator language it is called PEEP — positive end-expiratory pressure. It keeps small air sacs deep in the lungs from collapsing at the end of each breath, which improves how much oxygen crosses into your blood. That is why in patients whose main problem is low oxygen rather than high CO₂, doctors lean on EPAP.

What raises EPAP: severe obstructive sleep apnoea, obesity hypoventilation syndrome, poor oxygen saturation, a thick neck, sleeping on your back. 

What keeps EPAP low: COPD, where too much back-pressure makes it even harder to push air out of already-trapped lungs.

There is one more thing worth knowing about EPAP. An EPAP of around 4 cmH₂O is often the recommended starting point simply to maintain continuous flow through the circuit and stop you re-breathing your own exhaled CO₂.

Which tells you something useful: EPAP is almost never set to zero, even when nobody's airway is collapsing.

IPAP: the number that fills the lungs

When the machine senses you starting to inhale, it ramps the pressure up from EPAP to IPAP. That surge does the work your tired breathing muscles cannot do alone. More pressure on inhale means more air moves in — a bigger tidal volume, in clinical language.

This is where BiPAP separates itself from CPAP entirely. CPAP is a single constant pressure: it holds your airway open but does nothing to help you actually move air. BiPAP adds a push. That push is why bilevel therapy is used for conditions where the problem is not just a blocked airway but weak or overworked breathing — COPD, neuromuscular disease, obesity hypoventilation, chest wall deformity, post-ICU recovery.

IPAP is therefore the setting that corrects nocturnal hypoventilation and daytime CO₂ retention — the level needed is determined by how much ventilation it takes to stabilise the blood gases.

Here is the practical consequence, and it surprises people: if your morning headaches are from CO₂, the number that fixes them is IPAP, not oxygen. Adding an oxygen cylinder to a patient who is retaining CO₂ can make things worse, not better. The machine has to move more air, not richer air.

Pressure Support: the number nobody explains, and the one that matters most

Here is the formula that unlocks the whole prescription:

Pressure Support (PS) = IPAP − EPAP

Also called delta pressure or ΔP. Same thing, three names.

IPAP 16 and EPAP 6? Your pressure support is 10 cmH₂O. IPAP 12 and EPAP 8? Pressure support is only 4 — a much gentler machine, despite the fact that 12 sounds "high."

That comparison is the entire point. A high IPAP does not mean strong support. A patient on IPAP 20 / EPAP 14 is receiving less breathing assistance than a patient on IPAP 16 / EPAP 6, even though the first number is bigger. What fills the lungs is the gap, not the ceiling.

In ventilator terms, the delta between EPAP and IPAP is identical to pressure support in pressure-support ventilation — just described differently.

The prescription trap that sends patients back to hospital

This is the single most common error in home non-invasive ventilation, and it is worth reading twice.

Different doctors write prescriptions in two different formats:

• Format A: "IPAP 15, EPAP 5" — absolute pressures

• Format B: "EPAP 5, PS 10" — a baseline plus a support value

These describe the same therapy. But if someone reads Format B and enters IPAP 10 into the machine instead of 15, the patient receives a pressure support of 5 instead of 10 — half the intended support, which is unlikely to correct alveolar hypoventilation at all.

The patient goes home. The machine runs all night, quietly, apparently working. The CO₂ never comes down. Two weeks later they are back in the emergency department, and nobody can work out why the BiPAP "failed."

What to do: before your machine leaves the shop, confirm with the technician that the pressure support on screen matches what your doctor intended — not just that the numbers on the slip were typed in. If your prescription says "PS", ask them to state the resulting IPAP out loud. Our team runs this check at every installation, and it takes thirty seconds.

Reading real prescriptions: four worked examples

What the slip says	Mode	PS (Δ)	What it means in plain language	Commonly seen in
IPAP 10 / EPAP 5	S	5	Gentle assist. Airway held open, small push on inhale	CPAP-intolerant mild OSA
IPAP 16 / EPAP 6	ST, BUR 12	10	Medium-high support. Meaningful help clearing CO₂, plus a safety-net breath rate	COPD with CO₂ retention
IPAP 20 / EPAP 10	ST, BUR 14	10	High baseline and strong push — heavy airway obstruction plus hypoventilation	Obesity hypoventilation syndrome
EPAP 6 / PS 12 / IPAP max 25	AVAPS or iVAPS	12 target	Machine varies IPAP breath by breath to hit a set air volume	Neuromuscular disease, complex COPD

Notice row three versus row four. Row four does not fix IPAP at all — it gives the machine a range and a volume target and lets it adjust. The maximum IPAP is capped for safety, and the minimum IPAP is generally set at EPAP + 4 cmH₂O. If your prescription has a range rather than a single IPAP, you are on a volume-assured mode, and you need a machine that supports it. Not all do. Our full breakdown of BiPAP modes and pressure settings covers which models offer which modes.

Normal IPAP and EPAP ranges by condition

The honest answer to "what is a normal setting" is that there is no normal — there is only appropriate for your lungs, on your test night. But knowing the usual territory helps you spot when something looks unusual and worth a question.

Condition	Typical IPAP	Typical EPAP	Typical PS	The clinical goal
OSA, cannot tolerate CPAP	8–14	4–8	4–6	Stop airway collapse comfortably
COPD with high CO₂	12–20	4–8	8–14	Clear CO₂; keep EPAP low to avoid worsening air trapping
Obesity hypoventilation	16–24	8–12	8–12	Higher EPAP for airway and oxygen, plus strong push
Neuromuscular / ALS	12–22	4–6	8–16	Do the work weak muscles cannot
Central sleep apnoea	10–18	4–8	6–10	Backup rate matters more than raw pressure

Published clinical starting points follow this same pattern. OSA titrations often begin near IPAP 8–10 with EPAP 4–5, while COPD and other respiratory conditions typically need IPAP 12–20 with EPAP 4–8, with backup rates landing around 12–16 breaths per minute. Most clinicians also avoid pushing IPAP past 20–25 cmH₂O because of the risk of air being forced into the stomach — the cause of the bloating and belching we cover in our article on aerophagia with CPAP and BiPAP.

The other numbers on your slip

Your prescription probably has more than three values on it. Here is the rest of the alphabet.

Setting	What it does	Why it is there
Mode (S / ST / T / PC / AVAPS / iVAPS)	Decides whether the machine waits for you or breathes for you	S waits. ST waits but steps in. T ignores you entirely
BUR / Backup Rate	Minimum breaths per minute the machine guarantees	The safety net if you stop breathing. Usually set below your own natural rate, around 12–16
Ti / Ti min / Ti max	How long each assisted breath lasts	Too long feels like being held under; too short feels like being cut off
Rise Time	How fast pressure climbs from EPAP to IPAP	Fast for air hunger in COPD; slow for comfort
Trigger / Cycle sensitivity	How easily the machine detects your effort	Wrong setting = machine and patient fighting each other
Ramp	Starts at low pressure and builds over 5–45 min	Comfort only. Falls asleep with you
Target tidal volume	The volume AVAPS/iVAPS aims to deliver	Usually around 6–8 ml per kg of ideal body weight
Humidifier level	Warms and moistens the air	Non-negotiable in Delhi winters — dry air at 16 cmH₂O will crack your nose open

The humidifier deserves a word. At these pressures you are moving an enormous volume of air across your nasal lining every night. In a Delhi December, unhumidified BiPAP produces nosebleeds, a raw throat, and a patient who quietly stops using the machine by week two. Set it, use distilled water, and clean the chamber. Our guide to replacing filters, tubing and masks covers the maintenance schedule.

When the numbers are wrong: symptoms to report

Machines do not tell you they are set incorrectly. Patients do — through symptoms. Learn these, write them down, and take them to your follow-up.

What you notice	Often points to	What to do
Morning headache, foggy until noon	CO₂ not clearing — pressure support may be too low	Ask about a repeat blood gas or CO₂ check
SpO₂ still low overnight despite good usage	EPAP may be insufficient, or oxygen needs review	Report your overnight oximetry to your doctor
Feels like exhaling against a wall	EPAP may be too high for you	Do not reduce it yourself — report the sensation
Bloating, belching, stomach discomfort	Air entering the stomach at high IPAP	Report it; also check mask fit and sleep position
Machine "fighting" your breathing rhythm	Trigger, cycle or rise-time mismatch	A technician can review these with your doctor's approval
Mask blowing off, loud leak alarms	Leak at high IPAP — mask type or size wrong	See our mask leak troubleshooting guide
Still exhausted after 6 weeks	Settings, adherence, or diagnosis needs revisiting	Book a review — do not just persist

Two of those deserve emphasis. A persistent morning headache on BiPAP is not normal and is not "adjustment." It is the classic sign of CO₂ retention, and it means the therapy may not be doing its main job. And high leak makes everything else meaningless — a machine set to IPAP 18 that is losing half its air to a bad mask seal is delivering nothing like 18. Fix the mask first, then judge the settings. Read how to choose the right mask type.

Some discomfort in the first two weeks genuinely is adjustment — our piece on how long it takes to adapt to BiPAP therapy explains where that line sits.

Your numbers decide which machine you can rent

This is the part families discover too late, usually at 10 PM on discharge night.

Not every BiPAP machine can deliver every prescription. Three specific limits catch people out:

1. Pressure ceiling. Most home bilevel devices top out around 25 cmH₂O. If your prescription needs IPAP 24, an entry-level unit is running at the very edge of its range.

2. Mode availability. Basic machines offer S and ST only. If your slip says AVAPS, iVAPS, PC or AE, a basic machine physically cannot run it — and no amount of settings adjustment will change that.

3. Backup rate. An S-only machine has no backup rate. For a patient with central apnoea or neuromuscular weakness, that is not a feature gap, it is a safety gap.

So take the prescription — not the diagnosis, the actual prescription — to whoever supplies your machine. "COPD patient" tells a supplier very little. "ST mode, IPAP 18, EPAP 6, BUR 14" tells them exactly which device to send.

Healthy Jeena Sikho stocks ResMed, Philips, BMC, Oxymed and Topson bilevel devices across the S, ST and volume-assured range. You can compare specifications on our BiPAP machine page, check current BiPAP machine prices or the ResMed BiPAP range.

Rent before you buy. This matters even more in Delhi, where the follow-up appointment at AIIMS, Safdarjung or Ganga Ram may be three or four weeks after discharge — long enough for a machine bought in a panic to become the wrong machine before the first review. When settings are new, they change — a review at four weeks often shifts the IPAP or the mode entirely. Rental plans start from around ₹3,500 a month and let the prescription settle before you commit five figures. Our guide on renting before buying and the rental cost breakdown walk through the maths.

Getting a correctly configured BiPAP machine in Delhi, tonight

Prescriptions are handed over at the worst possible hour — usually after evening rounds, usually with the family already exhausted and the medical shops closing. Healthy Jeena Sikho runs three Delhi locations, at Bhogal, Tri Nagar and Uttam Nagar, specifically so that no part of the city is more than a short run from a stocked, correctly configurable machine.

Below is exactly where each location delivers, and which hospitals families in that belt are usually discharged from. Find your locality, and you will know which team is coming and how fast.

South, Central and South-East Delhi — served from Bhogal

Your locality	Hospitals families are discharged from
Bhogal, Jangpura, Nizamuddin, Lodhi Colony, Defence Colony, Lajpat Nagar	Moolchand, AIIMS
Greater Kailash, Andrews Ganj, Chirag Delhi, Shahpur Jat, Green Park, Hauz Khas	Fortis Greater Kailash, Max Smart Saket
Safdarjung Enclave, Sarojini Nagar, Moti Bagh, Vasant Vihar, Vasant Kunj, Chanakyapuri, Dhaula Kuan, Delhi Cantonment	AIIMS, Safdarjung Hospital, Fortis Vasant Kunj
Saket, Lado Sarai, Kishangarh, Sainik Farms, Chhattarpur, Sangam Vihar, Malviya Nagar	Max Saket, Indian Spinal Injuries Centre
Kalkaji, Govindpuri, Alaknanda, Tughlakabad, Sarita Vihar, Jasola, Okhla, Jamia Nagar, Shaheen Bagh, Abul Fazal	Apollo Jasola, Holy Family
Karol Bagh, Rajendra Nagar, Paharganj, Patel Nagar, Kirti Nagar, Moti Nagar, Anand Parbat	Sir Ganga Ram, BLK-Max
Laxmi Nagar, Shakarpur, Geeta Colony, Karkardooma, Preet Vihar, Vivek Vihar, Kalyan Puri, Trilok Puri, Mayur Vihar, New Ashok Nagar, IP Extension	Max Patparganj, Dharamshila Narayana
Noida Sector 62, Harola, Nithari, Chilla, Mamura, Khora, Indirapuram, Vaishali, Kaushambi	Fortis Noida, Kailash Hospital

Patients discharged from AIIMS and Safdarjung frequently come home on ST-mode bilevel with a backup rate, usually after an acute COPD exacerbation. That backup rate is not optional and not every entry-level machine has it — so read the mode out when you call, not just the diagnosis.

West and South-West Delhi — served from Uttam Nagar

Your locality	Hospitals families are discharged from
Uttam Nagar, Nawada, Hastsal, Mohan Garden, Bindapur, Matiala	Rao Tula Ram, Sanjay Gandhi Memorial
Janakpuri, Vikaspuri, Tilak Nagar, Hari Nagar, Subhash Nagar, Rajouri Garden	Mata Chanan Devi, Janakpuri Super Speciality
Dwarka Sectors 1–23, Mahavir Enclave, Sagarpur, Palam, Raj Nagar, Dabri	Venkateshwar, Manipal Dwarka, Ayushman
Najafgarh, Goyla Khurd, Qutub Vihar, Chhawla, Shyam Vihar, Papravat, Bijwasan	Rao Tula Ram, Aakash Healthcare
Nangloi, Mundka, Lok Nayak Puram, Peeragarhi, Paschim Vihar	Sanjay Gandhi Memorial, Action Balaji
Mayapuri, Naraina, Delhi Cantonment, Dhaula Kuan, Inderpuri	Base Hospital, BLK-Max

Two practical notes specific to this belt. In Dwarka's high-rise societies, tell us the tower, floor and lift status when you call — a technician stuck at an RWA gate without clearance loses twenty minutes before he reaches the flat. In older Janakpuri, Uttam Nagar and Hastsal blocks, staircases are narrow; a bilevel unit is light, but if an oxygen concentrator or hospital bed is going up alongside it, we send two people rather than one.

North and North-West Delhi — served from Tri Nagar

Your locality	Hospitals families are discharged from
Tri Nagar, Sarai Rohilla, Shastri Nagar, Kamla Nagar, Shakti Nagar, North Campus	Hindu Rao, St Stephen's
Ashok Vihar, Model Town, Shalimar Bagh, Wazirpur, Azadpur	Fortis Shalimar Bagh, Max Shalimar Bagh
Pitampura, Rohini, Prashant Vihar, Rani Bagh, Paschim Vihar, Rithala	Maharaja Agrasen, Jaipur Golden, Saroj Super Speciality
Punjabi Bagh, Moti Nagar, Kirti Nagar, Patel Nagar, Karol Bagh, Rajendra Nagar	Sir Ganga Ram, BLK-Max
Badli, Bhalswa, Jahangir Puri, Burari, Swaroop Nagar, Alipur, Bawana, Narela, Sultanpuri, Begampur, Kanjhawala, Siraspur, Barwala, Hamidpur	Satyawadi Raja Harishchandra, Maharishi Valmiki
Old Delhi, Sadar Bazar, Majnu Ka Tila, Wazirabad, Gandhi Nagar, Seelampur, Babarpur, Yamuna Vihar	LNJP, GTB Hospital

This is our fastest-response belt in Delhi, and the one where we most often manage genuine same-night setups — particularly for patients leaving the Punjabi Bagh, Shalimar Bagh and Maharaja Agrasen clusters.

Outside Delhi

We also deliver across Noida, Greater Noida, Gurgaon, Ghaziabad and Faridabad. Call and name your sector or locality — we will tell you honestly whether a same-day setup is realistic tonight or whether it is a next-morning delivery, rather than promising and missing.

Call +91 98769 78488. Keep the discharge summary in your hand — reading out the mode, IPAP, EPAP and backup rate takes ten seconds and means the correct machine leaves the warehouse the first time.

Call +91 98769 78488. Keep the discharge summary in your hand when you call — reading out the mode, IPAP, EPAP and backup rate takes ten seconds and means the correct machine leaves the warehouse the first time.

Your first 72 hours: a practical checklist

1. Photograph the prescription the moment you receive it. Discharge summaries get lost. Screenshots do not.

2. Verify the settings on screen at installation — mode, IPAP, EPAP, backup rate, and if applicable the resulting pressure support.

3. Ask for the clinician menu to be locked so settings cannot be changed accidentally.

4. Fill the humidifier with distilled water, not RO or boiled tap water.

5. Fit the mask sitting up and awake, before bedtime. See our mask fitting guide.

6. Note usage hours and leaks from the machine screen each morning for the first week.

7. Track morning symptoms — headache, alertness, breathlessness. This is the data your doctor actually needs at follow-up.

8. Do not change a single number. Not once. Not by one point. Ring the doctor instead.

Frequently asked questions

Q1. What is the full form of IPAP and EPAP? 

IPAP stands for Inspiratory Positive Airway Pressure, delivered while you breathe in. EPAP stands for Expiratory Positive Airway Pressure, maintained while you breathe out. Both are measured in centimetres of water pressure (cmH₂O).

Q2. What does IPAP 16 EPAP 6 mean?

It means the machine delivers 16 cmH₂O while you inhale and holds 6 cmH₂O while you exhale, giving a pressure support of 10 cmH₂O. This is a medium-to-high level of breathing support, commonly prescribed for COPD patients with carbon dioxide retention.

Q3. Which is more important, IPAP or EPAP? 

Neither alone. EPAP controls airway collapse and oxygenation; IPAP controls how much air moves and therefore how much CO₂ you clear. The difference between them — pressure support — is what determines the actual breathing assistance you receive.

Q4. Is IPAP 20 too high? 

Not necessarily. IPAP 20 is common in obesity hypoventilation and severe COPD. Clinicians generally avoid going far beyond 20–25 cmH₂O because higher pressures increase the risk of air entering the stomach, but the appropriate number depends entirely on your test results.

Q5. What is a normal EPAP setting? 

Home EPAP most often sits between 4 and 10 cmH₂O. It is rarely set above 12. Higher EPAP is used when the airway collapses heavily or oxygen levels are poor; lower EPAP is preferred in COPD to avoid worsening air trapping.

Q6. What is delta pressure in BiPAP? 

Delta pressure is another name for pressure support: IPAP minus EPAP. A larger delta means a bigger push of air with each breath and more ventilatory support.

Q7. Can I change my own IPAP and EPAP settings? 

No. Settings are determined by titration and blood gas results, and adjusting them without medical supervision can mask deterioration or cause harm. If the therapy is uncomfortable or ineffective, report the specific symptom to your doctor rather than altering the machine.

Q8. Why do I still wake with a headache on BiPAP? 

A morning headache typically signals retained carbon dioxide, which usually means the pressure support is too low, the mask is leaking badly, or usage hours are too short. It is a reason to seek review, not a normal part of adjustment.

Q9. Do IPAP and EPAP settings change over time? 

Frequently. Weight change, disease progression, a chest infection or improved adherence can all shift what you need. Most patients are reviewed within four to twelve weeks of starting, and settings are often revised at least once.

Q10. What BiPAP settings are used for COPD? 

Typically IPAP 12–20 and EPAP 4–8, giving pressure support of roughly 8–14, usually in ST mode with a backup rate. EPAP is kept relatively low because high expiratory pressure makes it harder for COPD patients to empty already over-inflated lungs.

Q11. What is the difference between BiPAP pressure and CPAP pressure? 

CPAP delivers one constant pressure throughout the breathing cycle. BiPAP delivers two — a higher inspiratory and a lower expiratory pressure. A CPAP set at 10 is roughly comparable to a BiPAP with EPAP 10 and no additional support.

Q12. Does a higher IPAP mean my condition is worse? 

Not reliably. Pressure requirements depend on body weight, airway anatomy, lung mechanics and the specific condition. Two people with similar severity can need very different numbers.

Q13. How do I know my BiPAP is working? 

Improved morning alertness, fewer headaches, better overnight oxygen saturation, and on repeat testing a lower CO₂ level. The machine's own data — usage hours, leak, and events per hour — supports this picture but does not replace clinical review.

Q14. Can I use a BiPAP machine with oxygen? 

Yes, oxygen is commonly bled into the circuit when prescribed. The flow rate is set by your doctor, and adding oxygen never substitutes for correct pressure support in a patient retaining CO₂.

Q15. What happens if the power goes out? 

Most home bilevel machines have no internal battery. In parts of Delhi where summer outages are still common — Uttam Nagar, Tri Nagar, Rohini and the older West Delhi blocks in particular — discuss battery backup or an inverter-compatible setup with your supplier before you need it, not during the first cut.

Q16. Where can I get a BiPAP machine on rent in Delhi with the correct settings? 

Healthy Jeena Sikho delivers and installs across Delhi from three locations — Bhogal for South Delhi including Safdarjung Enclave and Greater Kailash, Uttam Nagar for Dwarka and Janakpuri, and Tri Nagar for Pitampura and Ashok Vihar. Same-day setup is available in most areas.

Call +91 98769 78488 with the discharge summary in hand so the mode, IPAP, EPAP and backup rate can be verified before the machine is dispatched.

Q17. Do you configure the machine to my prescription, or do I have to do it? 

Our technician enters and verifies the prescribed settings at installation and locks the clinician menu so nothing is changed accidentally. You should never have to configure a bilevel device yourself.

The one-line summary

EPAP holds your airway open, IPAP fills your lungs, and the gap between them — pressure support — is what actually does the breathing work. Read the gap, not the ceiling. Report symptoms, never adjust numbers. And make sure the machine you bring home can physically deliver what the slip on your table says.

Need help matching a prescription to a machine?

Call +91 98769 78488 — have the discharge summary with you. Browse everything on our BiPAP page or the full equipment shop.

Medical disclaimer: This article is for general education and does not constitute medical advice. BiPAP pressures, modes and backup rates must be prescribed and adjusted only by a qualified physician based on individual assessment. Never change your machine's settings yourself. If you experience worsening breathlessness, confusion, drowsiness or chest pain, seek emergency medical care immediately.