1. Peripheral vs Central Access

Peripheral access:

Includes short peripheral IVs (<6 cm) and midlines (8–20 cm).

• Peripheral IVs: Inserted in hand or forearm veins for short-term use (3–5 days). Use feet only when upper extremity access isn’t possible.
• Midlines: Placed in larger upper-arm veins for 1–4 weeks (up to 30 days max). They’re more durable but don’t reach central circulation.

Central access:

Catheters with the tip in central veins, classified as:

• Non-tunneled Centrally inserted CVC:
  • These include internal jugular, subclavian, and femoral central lines.
  • They are used for short-term access — usually less than two weeks.
  • Subclavian is preferred for short-term use because it’s more comfortable and has a lower infection risk, but we avoid subclavian lines in CKD or ESRD patients because they can cause venous stenosis and compromise future dialysis access.
  • Femoral central lines should be reserved for emergencies or when the internal jugular or subclavian sites aren’t possible.

Two special types of non-tunneled central lines deserve mention:

1. Temporary dialysis catheters: These are large-bore central lines used when a patient needs urgent dialysis or CRRT. They’re usually placed in the right internal jugular or femoral vein if IJ access isn’t possible. If the need for dialysis becomes long-term, these should be transitioned to a tunneled dialysis catheter, like a Permacath.
2. Cordis — also called an “introducer sheath”: This is a short, large-bore central line that provides rapid access to the central circulation.
   It’s used when we need fast fluid resuscitation, multiple infusions, or when placing a Swan-Ganz catheter in the ICU or OR. Cordis lines are meant for very short-term use — usually hours to a few days.

• PICC line (Peripherally inserted central catheter): These catheters re placed in the arm and their tips end in the superior vena cava. Can stay for weeks–months (up to 6) for prolonged IV therapy, TPN, chemo.
• Tunneled CVC (Hickman, Permacath): These are designed for long-term and frequent access — They run under the skin before entering the vein, which helps reduce infection risk. They’re commonly used for dialysis, parenteral nutrition, and ongoing chemotherapy.
• Implanted Port (Port-a-Cath): These are fully under the skin. They’re accessed only when needed, require very little day-to-day care, and can last for years — often permanently — when maintained well.

2. Venous Accesses Ranking

By invasiveness from least to most:

Peripheral IV → Midline → PICC → Non-tunneled CVC → Tunneled CVC → Implanted Port

By duration:

Peripheral IV (3–7 days) → Non-tunneled CVC (days–3 weeks) → Midline (1–4 weeks) → PICC (weeks–months) → Tunneled (months–years) → Port (>5 years)

By infection risk (lowest to highest):

Port ≈ Peripheral IV → Midline → Tunneled → PICC → Non-tunneled (Femoral highest)

By thrombosis risk (highest to lowest):

Subclavian (long-term) → PICC → Femoral → Port → Tunneled/IJ → Midline → Peripheral IV

By phlebitis risk (highest to lowest):

Peripheral IV → Midline → PICC → Others (minimal)

3. Choosing the Right Access

Always start with the least invasive line that meets your patient’s needs.

• Peripheral IV:
  • Default choice; suitable for most short-term infusions (including vasopressors, hypertonic saline, amiodarone ≤24h).
  • Use 18–20G or larger, and monitor closely.
  • If peripheral access fails → use ultrasound-guided IV, midline, CVC, or IO access based on context.

• Midline: Ideal for 1–4 weeks of non-vesicant therapy (e.g., 2-week IV antibiotics for MSSA).
• PICC: Use for > 4-week therapy, TPN, or multiple infusions.
• Non-tunneled CVC: For critical illness, RRT, TPN, or multiple drips.
  • Subclavian preferred short-term (except in CKD/ESRD).
  • Right IJ is preferred in CKD.
  • Femoral: emergencies only.
• Tunneled & Ports: For long-term access (HD, chemo, TPN). Ports for intermittent use, tunneled for continuous.

4. Contraindications

• Avoid limb placement (peripheral/midline/PICC) if:
  • Prior mastectomy/axillary node dissection
  • AV fistula/graft
  • DVT, severe venous obstruction
  • Infection, burn, wound, or prior radiation
• Avoid placing central lines at:
  • Infected or distorted insertion site
  • Ipsilateral chest tube, ICD, or pacemaker
  • Vein thrombosis or occlusion
• Special cases:
  • Coagulopathy: Safe if platelets ≥20K and INR ≤2. Use ultrasound.
    • 10–20K → transfuse one platelet unit if noncompressible site.
    • INR 2 → correct to ≤2 before placement.
  • Bacteremia:
    • Safe to place a new non-tunneled CVC if no existing catheter.
    • Avoid inserting new CVC if another one is present—remove the first one if it’s the suspected source (especially with S. aureus, Candida, or GNRs).
    • Do not place a tunneled or port until bacteremia clears.

5. Daily Care and Removal

• Ask daily: Does this patient still need the line?”
• Inspect daily:
  • Site: redness, pain, drainage
  • Dressing: clean, dry, intact
  • Catheter: secured, correct external length
• Maintenance:
  • Flush before/after meds; unused lumens daily
  • Change transparent dressings q7 days; gauze q2 days
  • Confirm tip placement (CXR or ECG-guided)
• Remove immediately if:
  • No longer needed
  • Suspected infection
  • Nonfunctional or malpositioned
• During removal:
  • Supine/Trendelenburg, have the patient hold breath/Valsalva, steady traction, occlusive dressing afterward.
  • If infection is suspected, culture the catheter tip.

6. Common Complications

• CLABSI:
  • Prevent with full sterile barrier, chlorhexidine prep, daily necessity checks, hub scrubbing, and prompt removal.
  • Suspect if fever or positive cultures >48h after insertion.
  • Draw cultures (line + peripheral), remove line, start empiric antibiotics.
• Thrombosis:
  • Most common with PICCs/subclavian lines.
  • Arm/neck swelling, pain, venous distention → confirm by ultrasound.
  • Treat with anticoagulation; remove only if infected or unnecessary.
• Mechanical Issues:
  • Pneumothorax: Get CXR post-subclavian or IJ.
  • Arterial puncture: Remove immediately, apply pressure for 10–15 minutes.
  • Air embolism: Trendelenburg + left lateral position, 100% O₂.
  • Malposition: Confirm and reposition before use.
• Catheter Dysfunction:
  • If sluggish or occluded → reposition, flush gently, or use Cathflo (2 mg, dwell 30–120 min).
  • Never force flush.

Special Scenarios

• CKD/ESRD: Avoid subclavian & PICCs; preserve future fistula veins.
• Cancer: Prefer ports for long-term intermittent therapy.
• Home IV therapy: PICCs are ideal—ensure patient education and home nursing follow-up.

Summary & Key Takeaways

• Start with the least invasive option.
• Midlines are underused—great for 1–4 weeks of therapy.
• PICC lines for long-term or outpatient IV therapy.
• Non-tunneled CVCs for emergencies and ICU patients.
• Remove lines early to prevent CLABSI.
• Avoid subclavian in CKD.
• Always confirm tip position before use.

Introduction

• A chest tube is a hollow, flexible tube that we place into the pleural space to drain air, blood, or fluid so the lung can re-expand.
• A pigtail catheter is simply a smaller, softer version of a chest tube, with a curled ‘pigtail’ tip.
• Both do the same job — removing air or fluid from around the lung — but the big difference is in size and invasiveness.

Indications

This table summarizes the indications of the traditional chest tube vs the pigtail catheter

The chest tube drainage unit

An adequate chest drainage system aims to:

1. Remove pleural fluid and/or air.
2. prevent their reflux into the pleural space.
3. Restore negative pleural pressure (less than atmospheric pressure) to allow lung re-expansion.

To understand how the chest tube achieves that, we must understand the components of the chest tube drainage unit.

The one-bottle unit

Back in the day, the chest tube unit was simply a tube connected to a bottle filled with saline/water and a one-way valve. While this works well for draining air, it doesn’t for fluid! If a pleural effusion is drained, the fluid level in the bottle will quickly increase, reducing the efficiency of removing additional fluid from the patient

The two-bottle unit

To solve this problem, a second water seal bottle was introduced! This leaves the first bottle for collection only and one for the water seal.

The three-bottle system

To improve drainage efficiency, a third bottle connected to external suction is added. a collection bottle, a water seal bottle, and a suction bottle.

The modern chest tube unit

Nowadays, all these bottles/chambers are currently integrated into a single modern, multifunctional, easy-to-manage unit.

The tube itself comes in different sizes and shapes. They can be straight, angled, spiral, or coiled at the end (referred to as “pig-tail”).

Confirmation of proper positioning with CXR

• Ideally, the tip of the chest tube should be positioned at the apex if inserted for pneumothorax, and at the base if inserted for fluid removal. Ensure the tip is not outside the pleural space or abutting the mediastinum.

The fenestrations seen on chest tubes are these evenly spaced gaps (interruption marks) along the radiopaque stripe of the tube. The fenestrations should be inside the pleural space to allow effective drainage of air or fluid while reducing the risk of clogging or blockage. Multiple holes also distribute suction evenly, preventing tissue trauma and ensuring continuous tube function.

The daily bedside checks on patients with chest tubes

1. Review the CXR first.

2. Assess the output in the collection compartment. Is it bloody or not? Is it increasing or decreasing?
3. Check for tidaling! Tidaling is the rise and fall of fluid in the water seal chamber with breathing. Watch this YouTube video showing tidaling!

Tidaling tells you the chest tube is working and still in contact with the pleural space. If tidaling disappears, it means one of two things:

• The lung has fully re-expanded — which is good —
• The tube is blocked — which is bad —

If the patient’s breathing comfortably, chest X-ray shows full lung expansion, and there are no signs of distress — that’s good. But if the patient is short of breath, there’s new subcutaneous emphysema, or the tube is kinked or clogged — that’s bad, it means obstruction.

4. Check for bubbling! Do you see any air bubbles in the air leak monitor? Check bubbles in the air leak monitor in this YouTube video:

Bubbling means air is still escaping. It could be from an ongoing air leak in the pleural space or a disconnection in the tubing outside the chest.

5. Check the dressing and assess the tube integrity from the dressing to the tube unit, particularly if you see a continuous bubbling in the air leak monitor.
6. Assess the Pain level! Chest tubes, especially large-bore ones, are painful, so please ensure adequate pain control.
7. Ask them to ambulate. Chest tubes don’t mean they can’t be ambulated.
8. Do they still need the chest tube?

Chest tube removal

The chest tube should only be removed by the team that placed and is actively managing it. Typically, the ICU, thoracic, cardiovascular, or trauma surgery team.

Removal is considered when:

• The active issue has been resolved, whether fluid or air.
• The lung has fully expanded.
• The patient is clinically stable.

For example, in cases of draining fluid, the amount in the collection compartment is consistently low; something like less than 20 cc/day for 1-2 days.

And for pneumothorax, you don’t see any air bubbles in the air leak monitor for 1-2 days, and the lung has fully expanded.

Typically chest tube is clamped for 12-24 hours (clamping deems the tube not functioning). If the patient’s conditions remained clinically stable with a stable CXR, then this means it’s time to remove the tube.

DO NOT CLAMP CHEST TUBE on your own unless you are part of the team who is actively managing it. DO NOT EVER CLAMP A TUBE IF YOU SEE AIR BUBBLES IN THE AIR LEAK MONITOR!

Some patients may need the chest tube for weeks and months, like malignant effusions. In such a case, a traditional chest tube can be replaced with a pigtail catheter to go home with.

Pitfalls & Warnings

• Don’t connect the chest tube to suction immediately after insertion to reduce the risk of re-expansion pulmonary edema. Re-expansion pulmonary edema is a non-cardiogenic edema that happens when a lung that’s been collapsed for days is rapidly reinflated — the fragile capillaries leak, flooding the alveoli. Management is supportive with oxygen, noninvasive ventilation, and cautious fluids. The real key is prevention: never drain too much, too fast.

Diuretics may worsen hypovolemia and are not recommended. The re-expansion pulmonary a non-cardiogenic edema driven by increased capillary permeability from reperfusion injury, not by fluid overload

• Watch for a blocked/clogged tube (no drainage but effusion enlarging). Sometimes, a thrombolytic is used for clogged tubes!
• Correct any tube kinking or dislodgment.

Learn the 8 bad lab habits in hospitals that waste resources and rarely change management. Discover smarter, evidence-based alternatives to improve patient care and reduce unnecessary testing.

Introduction

I can’t remember the last time I finished a shift without a call about a patient in acute pain. In this post, I’ll share a practical, easy-to-use guide to help you choose the right analgesia for your patients.

Pain severity scale

The first and most important step—often overlooked—is to assess the severity of pain using a standardized pain scale. In the hospital, this is typically a numerical rating scale, where patients are asked to rate their pain from 0 to 10. A score greater than 6 is generally considered severe.

Mild pain

This is pretty straightforward. Oral acetaminophen alone or in combination with a low-dose oral NSAID can be used. An ideal mild pain regimen would consist of:

• Acetaminophen 650 mg orally every 4 hours as needed.
• Ibuprofen 400 mg orally every 4 hours as needed.

The nurse should administer either option, but not both at the same time. They may alternate between the two if needed.

Personally, I prefer the sole use of acetaminophen in the mild pain category.

Moderate pain

A high-dose Oral NSAID with or without low-dose IV acetaminophen.

IV NSAIDs are an option here, as well. In such a case, oral NSAIDs should be discontinued. An ideal regimen would consist of:

• An NSAID (Pick one):
  • Naproxen 500 mg orally twice daily as needed.
  • Ibuprofen 600 mg orally every 6 hours, or Ibuprofen 800 mg orally every 8 hours as needed.
  • Ketorolac 15 mg IV every 6 hours as needed.
• If NSAIDs are contraindicated or inadequate, Acetaminophen 650 mg IV every 6 hours as needed can be added.

Severe pain

This is the category where opioids should be used! Opioids should be reserved for severe pain only, including oral & IV opioids! This may seem odd, as a lot of hospital pain protocols include low-dose oral and IV opioids for moderate pain. Please avoid that unless there is a contraindication to use acetaminophen and NSAIDs!

Why am I saying this?

Adding opioids for moderate pain will likely lead to unnecessary and avoidable use of opioids!

Just imagine your patient is having moderate pain based on the assessment scale, and you have the option to pick between a low-dose opioid or an NSAID, most of us will unconsciously lean toward picking the stronger analgesic, which is an opioid here, although a dose of naproxen would have been probably adequate!

So, unless there is a contraindication to use NSAIDs or Acetaminophen, reserve opioids for severe pain only, please.

But does that mean opioids are the only option for severe pain? Of course not!

High-dose IV Acetaminophen and IV NSAIDs are pretty effective in severe pain as well.

So an ideal regimen for severe pain analgesics would consist of:

• IV Acetaminophen or IV NSAIDs (First line)
• Oral opioid (Second line)
• IV opioid (Last to use).

I will go for IV NSAIDs or Acetaminophen first, oral opioids second, and IV opioids are our last resort if the patient’s acute pain remains inadequately controlled

Remember that NSAIDs are first-line analgesics in the following conditions:

• Renal colic, IV Ketorolac in particular, is effective here.
• Musculoskeletal pain like arthritis pain, pleuritic-type chest pain, rib fracture, and muscular strains.
• Incisional post-operative pain.

Acetaminophen is particularly effective in most types of headaches alone or in combination with caffeine.

Also, the location of pain may warrant analgesia avoidance, like chest pain of cardiac origin, where NTG should be used instead.

Now, which opioid should we use and what dose? I refer you to an older post where I discussed the use of opioids. You can read it here

Persistent severe pain

In persistent severe pain where the patient keeps requiring recurrent doses of opioids despite treating or while treating the underlying cause of pain, we need to try to reduce the pain level with other means and consequently reduce the need for IV opioids:

• Adding scheduled (Not PRN) oral acetaminophen or oral NSAID, remember to discontinue their IV equivalents.
• Adding Gabapentin
• Adding a scheduled low-dose oral opioid can be considered if previous measures didn’t help reduce the use of IV opioids.

   

Let me give you an example:

A 64-year-old lady was admitted with a pelvic fracture, she’s in severe pain her severe pain regimen consists of the following:

• Ketocorolac 15 mg IV every 6 hours as needed
• Oxycodone/acetaminophen 5/325 mg PO every 4 hours as needed
• Morphine 4 mg IV every 6 hours as needed

You reviewed her chart and found that she received 12 doses of IV morphine over the last three days, her nurse reported that IV morphine is the only thing keeping her pain under control and she asked you if there’s anything we could do to help her pain control.

Of course, the first thing I do is check if the patient has received IV Ketorolac and oxycodone/acetaminophen or if the nurse just jumped to IV morphine, if they have not been tried, I will ask the nurse to try them first and assess the response! If they have already been given with inadequate response, then we can do the following:

• Add scheduled high-dose oral ibuprofen, or naproxen, or acetaminophen
• Add Gabapentin
• If that remains inadequate, we add a scheduled oral opioid for a few days while escalating the Gabapentin dose

Please remember this about the use of Acetaminophen and NSAIDs:

• Don’t combine oral and IV forms of the same medication or the same class within the same severity category, for example, don’t use oral naproxen and IV ketorolac together for moderate pain, or oral acetaminophen and IV acetaminophen together for severe pain.
• Combining acetaminophen at doses higher than 2 g/day together with an NSAID isn’t more effective than an NSAID alone and might be associated with a higher risk of gastrointestinal complications! So keep that in mind!
• The total daily amount of acetaminophen shouldn’t exceed 4 g/day including all forms of acetaminophen, whether oral or IV, and the one combined with oral opioids.

More options for severe pain

There are other options to consider in severe pain cases:

• Regional block performed by surgery or anesthesia can be helpful in rib fractures or postoperative pain
• Ketamine can be considered in severe pain refractory to opioids.
• Dexamethasone can be considered where swelling and edema are suspected as a contributing factor to the pain line in disk herniation or metastatic bone pain.
• Local anesthetics like lidocaine patches are not that effective in acute severe pain management, but they can be used as an adjuvant therapy to other analgesics for superficial musculoskeletal pain.
• Muscle relaxants can be considered when muscle spasms may contribute to the patient’s acute pain

In this post, I’ll walk you through 10 medications you absolutely must master before your ICU rotation.

These 5 ICU hacks will save you at least two hours a day—and make you look sharp, confident, and in control from day one

Introduction:

Mechanical ventilation doesn’t have to be intimidating. If you are a non-ICU doc who just wants to feel more prepared when your patient gets intubated, this post is for you! I’m pretty sure after this, you won’t shy away from the ventilator again.

So grab a coffee, and let’s finally make sense of mechanical ventilation. Let’s get started.

Concept (1): The respiratory cycle has two phases: expiration and inspiration.

Inspiration is an active process that requires energy. Expiration is typically passive, relying on the lungs’ natural elastic recoil.

The respiratory cycle duration is calculated by dividing 60 seconds by the respiratory rate (RR). This cycle encompasses both inspiratory and expiratory time. The relationship between inspiration and expiration is not equal; physiologically, the ratio of inspiratory time to expiratory time (I:E) is typically 1:2 or 1:3, with expiration being longer than inspiration.

Example:

RR = 20 breaths/minute

The respiratory cycle duration = 60/20 = 3 seconds

Using I:E ratio of 1:3, the inspiratory time would be 0.75 seconds, and the expiratory time would be 2.25 seconds.

Concept (2): The ventilator does the heavy lifting during inspiration, but it doesn’t clock out during expiration!

As we mentioned earlier, inspiration is an active process that requires energy, so the ventilator works mainly during this active, energy-consuming phase. But that doesn’t mean the ventilator just shuts off during expiration—it continues to play a crucial role by maintaining a certain level of pressure that is called PEEP, or Positive End-Expiratory Pressure.

PEEP prevents the alveoli from collapsing at the end of expiration by holding a small amount of pressure in the lungs throughout the entire respiratory cycle, not just during the expiration phase. Think of it like a doorstop that keeps the alveoli slightly open, making the next breath easier and improving oxygenation.

Don’t be fooled by the name—PEEP isn’t just at the end of expiration. It’s present throughout the entire respiratory cycle. During expiration, it’s the only pressure applied, and during inspiration, the ventilator adds pressure on top of the PEEP to deliver the breath.

Concept (3): Air flows from higher-pressure to lower-pressure areas.

During inhalation, air enters the lungs because the pressure at the nose and mouth is higher than in the alveoli. During exhalation, the pressure in the alveoli becomes higher than at the airway opening, so air flows out. This air movement continues as long as a pressure gradient exists. In spontaneous breathing, we actively lower the pressure inside the alveoli below atmospheric pressure, creating suction and pulling air in.

In mechanical ventilation, the ventilator does the opposite: it raises the pressure at the nose and mouth above alveolar pressure to push air in. That’s why we call it a positive pressure breath

Concept (4): To get air in, the ventilator has to fight three battles: the tube, the airways, and the lungs.

During mechanical ventilation, the ventilator delivers air through the endotracheal tube (ETT), down the airways, and into the alveoli. To do this, it must overcome two main types of resistance:

• The airway resistance (from the ETT and conducting airways).
• The elastic resistance (from the alveoli and lung tissue).

The airway resistance

This resistance is primarily due to their narrow lumens and flow dynamics. The pressure required to overcome this kind of resistance is called Resistive pressure, and it is calculated by multiplying the flow by the airway resistance.

The elastic resistance

The alveoli are evaluated based on their compliance—their ability to stretch and accommodate volume. The pressure required to overcome alveolar and lung tissue stiffness is called Elastic pressure, and it’s calculated by dividing volume by compliance.

Therefore, for a full breath to be delivered, the ventilator must generate enough total pressure to overcome both the resistive and elastic or alveolar pressures. In mechanical ventilation, this pressure is called the peak inspiratory pressure (PIP).

Based on this equation:

• PIP is proportionally related to Flow, airway resistance, and TV.
• Inversely related to compliance.

Take a peek at this ventilator screen: The PIP is 20 cmH2O, the flow rate is 44 L/min, and the tidal volume is 500 mL.

• Guess what will happen to the PIP if I increase the flow or the tidal volume? Based on the equation, the peak inspiratory pressure (PIP) will increase.
• What will happen to the PIP if the patient bites the endotracheal tube or develops bronchospasm, both of which increase airway resistance? Again, you’ll also see a rise in PIP.
• Let’s say the patient develops pulmonary edema and bilateral pleural effusion. What would happen to the PIP in such a case? Pulmonary edema and bilateral pleural effusion reduce the alveoli’s ability to accommodate tidal volume (reduce their stretchability and compliance). PIP is inversely related to compliance; now the ventilator has to push harder to get the breath in, which means higher PIP is required!

Concept (5): Plateau Pressure: Your Window into Lung Compliance

Let’s imagine a moment when the flow drops to zero— this occurs briefly at the end of inspiration, just before expiration begins, and again at the end of expiration, just before the next inspiration starts. These are the transition points between phases of the respiratory cycle when there’s no airflow because the pressures between the airway and alveoli are equal.

Guess what happens to the PIP when the flow drops to zero? Let’s go back to our equation:

                                                                                        PIP = (Flow×Resistance) + (Tidal Volume/Compliance)

If the flow drops to zero, the resistive component disappears, and the equation simplifies to:

                                                                                       PIP = TV/Compliance = Alveolar Pressure.

This means when the flow is zero, the PIP is equal to the alveolar pressure, and this makes sense as pressure gradient means flow, and the absence of the gradient means no flow.

In mechanical ventilation, the pressure measured at the end of inspiration when the flow ceases is known as the Plateau pressure. Plateau pressure provides great insight into lung compliance. The lower the plateau pressure, the more compliant, stretchable, and less stiff the lung is, and vice versa!

How do we measure the plateau pressure? Plateau pressure is measured using the inspiratory pause or hold maneuver. In clinical practice, we aim for a PIP < 35 cmH2O and a plateau pressure of < 30 cmH2O.

How about the opposite? I mean the pressure measured at the end of expiration and before the inspiration valve opens? What do you think the alveolar pressure should be in such a case? We mentioned earlier that PEEP is the only pressure the ventilator provides during expiration, which means the expiratory flow will continue until the alveolar pressure drops from the maximum value at the end of inspiration (plateau pressure) down to the PEEP value, when the flow ceases. So normally, the alveolar pressure measured at the end of expiration when there is no flow must equal PEEP.

To confirm that, we perform what we call the expiratory pause maneuver. This maneuver allows us to check for any gas trapping and autoPEEP.

Concept (6): The ventilator can’t think for itself—it needs our guidance

For the ventilator to function properly, we have to give it five instructions:

• When to start the breath.
• How to deliver the breath.
• When to terminate the breath.
• How much oxygen to give?
• How much PEEP to give?

1. When to start the breath or inspiration?

The ventilator listens to the patient to detect the patient’s inspiratory effort. It will pick up any inspiratory effort as a sign that the patient is trying to breathe, and it will assist the patient with that breath! This is known as a patient’s triggered breath or, as we call it in mechanical ventilation, an Assist breath or “A” breath.

But what happens if the ventilator doesn’t detect any patient trigger? Let’s say the patient is paralyzed or brain-dead.

In this case, the ventilator has a built-in safety mechanism: it will deliver a breath if no patient’s trigger is detected for a specific time! This is called a backup breath or, as we call it in mechanical ventilation, a Control breath or “C” breath.

Take a look at these two ventilator screens. The breath on picture A is a controlled or backup breath labeled as C breath, and the breath on picture B is an assist breath triggered by the patient and assisted by the ventilator.

But what decides how long the ventilator should wait before delivering a backup breath? This timing is based on the set respiratory rate (RR), which is known as the backup rate. The backup rate is the minimum number of breaths/minute the patient receives, even if they make no effort to breathe. The ventilator will listen to the patient for a period equal to [60 sec/backup RR] before delivering the backup breath.

Example: If the backup rate is set to 15 breaths per minute, the ventilator waits up to 4 seconds (60 ÷ 15), and if no patient’s trigger is detected, a backup breath will be delivered!

The actual RR is either equal to or higher than the backup rate, but never lower! This is important when trying to adjust the backup RR. Let’s say the backup rate is 14 and the patient is breathing at 20 breaths/min; there is no point here if you increase the backup rate to 16 because the actual RR is already higher!

Take a look at this ventilator screen, see the set backup rate at 18 while the actual RR on the top is 28. Increasing the backup rate will not have any impact unless it becomes higher than the actual RR.

The values at the bottom of the picture are the set values that we provide, while those at the top are the actual live values! The ventilator tries to fulfill the set values or close to them (See the set TV is 500, but the actual one is 524).

Back to the trigger, how does the ventilator detect the patient’s trigger?

In spontaneous breathing, the patient generates negative pressure in the alveoli, which creates a suction effect that pulls air in. When the patient is intubated and connected to a ventilator, this same effort draws air through the circuit, and that’s how the ventilator knows it’s time to assist.

Take a look at the ventilator circuit picture below: you’ll notice two limbs connected to the endotracheal tube (ETT)—the inspiratory limb, which carries air from the ventilator to the patient (often passing through a humidifier), and the expiratory limb, which returns air from the patient back to the machine.

When the patient is not making any effort, air flows equally through both limbs. When the patient initiates a breath, he pulls some air from the inspiratory limb into his lungs, reducing the flow returning through the expiratory limb. The ventilator senses this imbalance and interprets it as an inspiratory effort and will go ahead and assist the patient with that breath. This is called a flow trigger.

Alternatively, the ventilator can detect a drop in airway pressure (caused by the patient’s inspiratory effort) and use that as a trigger. This is called a pressure trigger.

🔁 To summarize: the ventilator can recognize a patient’s attempt to breathe in two ways:

• Flow Triggering – by sensing a drop in flow through the expiratory limb.
• Pressure Triggering – by sensing a drop in airway pressure.

Take a look at these two screenshots of two ventilators:

• On Picture A, Psens shows the pressure trigger. It’s set at 2 cm H₂O, meaning the patient must reduce his airway pressure by at least 2 cm H₂O to trigger a breath. We usually set this between 2 and 3 cm H₂O.
• On picture B, Vsens represents the flow trigger, set at 3 L/min. This means the patient must draw in at least 3 L/min (approximately 50 mL/sec) for the ventilator to deliver a breath.

Whether using a flow trigger or a pressure trigger makes no clinical difference—neither offers a clear advantage over the other.

2. How should the ventilator deliver this breath?

In mechanical ventilation, we refer to the way of delivering the breath as the “target.” Although the term can be confusing, the concept is straightforward—just give me your full attention!

Let’s bring back our lovely equation again:

PIP = (F x R) + (TV/C).

Which can be rewritten as: PIP = (F x R) + Alveolar pressure. Which can be rearranged into: F = (PIP – Alveolar pressure) / Resistance.

In mechanical ventilation, we can directly set the flow rate and the peak inspiratory pressure (PIP) on the ventilator. However, alveolar pressure and airway resistance are not directly settable—they’re influenced by the patient’s lung mechanics and underlying condition.

Based on the equation, mathematically, for the pressure–flow relationship to hold true, we can only set one variable—either the pressure or the flow, but not both. That’s because one must remain flexible to allow the other to stay fixed. If we fix both, the equation wouldn’t hold under changing patient conditions.

This will leave us with one of two options to deliver the breath:

• You can either set the flow and let the pressure adjust, which is called the flow target.
• Set the pressure and let the flow adjust, which is called the pressure target.

In flow-targeted ventilation, we start by setting the desired flow rate. From there, we have two main subtypes based on how that flow is delivered:

1. We can ask the ventilator to keep the flow rate fixed throughout the inspiratory phase, which results in a square or rectangular flow vs time curve.
2. Or we can ask the ventilator to give the set flow rate only at the beginning of the breath, and let it progressively drop or decelerate throughout the rest of the inspiratory phase! This results in a decelerating ramp flow vs time curve.

Take a look at this flow target on this ventilator screen and notice:

• The green curve shows the decelerating ramp flow pattern.
• On the info panel, the flow target is set at Vmax: 44 L/min with the ramp type set to decelerating.

How about the pressure target ventilation?

Here, we tell the ventilator to apply a fixed amount of pressure on top of the PEEP throughout the inspiratory phase until the breath is delivered.

What do you think the flow pattern will be in the pressure target? To maintain a fixed pressure throughout the inspiratory phase, the flow must progressively decrease to keep this equation valid, “F = (PIP – Alveolar pressure) / Resistance”. Of course, as long as the resistance is constant. That’s why the flow vs time curve is always a decelerating ramp curve in pressure target modes.

Take a look at this ventilator screen, see the fixed pressure here. The ventilator adds 20 cmH2O on top of PEEP of 10 and keeps it there during the whole inspiration. The flow curve is a decelerating ramp curve.

What do you think will happen to the flow rate if we set the inspiratory pressure (Pi) at 30 cmH2O instead of 20?

If we increase the inspiratory pressure from 20 to 30 cmH₂O, the flow rate will increase; so the higher the set pressure, the greater the initial flow the ventilator delivers.

3. When should the ventilator stop delivering the breath (Cycle)?

This is known as the ‘cycle’ in mechanical ventilation. There are three main mechanisms to determine when the ventilator stops inspiration and switches to expiration. These are known as cycling mechanisms:

Volume-Cycled Ventilation:

In volume-cycled breaths, the ventilator ends inspiration once the preset tidal volume (TV) is delivered.

🔍 Look at the ventilator screen below and see the volume vs time curve. Once it reaches the desired TV, it will switch from green color, which represents inspiration, to yellow color, which represents expiration. Also, look at the top panel and see that the actual TV was 315! In reality, the ventilator doesn’t always fulfill the exact set TV, but it will be close to that!

What do you think will happen to the inspiratory time if we increase the TV here? Of course, it will increase; the larger the volume, the longer it takes to deliver it. The opposite is true.

Time-Cycled Ventilation:

In time-cycled breaths, the ventilator switches to expiration after a preset inspiratory time has elapsed, regardless of the volume delivered.

🔍 Check the ventilator screen for the set inspiratory time and see that the green line in all the curves switches to yellow after the set inspiratory time.

What do you think the TV will be if we shorten the insp time? It will be smaller as we spending less time delivering the breath, the opposit is true.

Flow-Cycled Ventilation:

In flow-cycled breaths—used primarily in pressure support mode—the ventilator ends inspiration when inspiratory flow drops to a preset percentage of peak inspiratory flow.

🔍 Look at this screen and see the “Esens” or expiratory sensitivity setting (commonly set at 25%)—the breath ends when flow falls to 25% of its peak during inspiration.

What will happen to the TV if we set ESens at 50% instead of 25%? It will be smaller as we are having a shorter inspiratory time! The opposite is true.

4. How much FiO₂ and how much PEEP? These two are oxygenation parameters, and we’ll discuss them later in this post.

Concept (7): Every Mode Is a Recipe: You Just Change the Ingredients

At the heart of mechanical ventilation are three fundamental modes:
🔹 Volume Control.
🔹 Pressure Control.
🔹 Pressure Support.

Every other mode you’ll encounter is either a hybrid or a modification of these three.

To make sense of any mode, just break it down into the three key ingredients we just explained:

🟢 Trigger – What starts the breath?
🟡 Target – How to deliver the breath?
🔴 Cycle – What ends the breath?

Before I go further!

If you’re finding this helpful, you’re going to love my full mechanical ventilation course. It covers everything we’re walking through in this video—from triggers, targets, and cycling to all the core modes—plus much more, like: Troubleshooting PIP, Rise time, Mean airway pressure, Auto-PEEP and gas trapping, Assessing weaning readiness, and how to do a proper weaning trial.

It’s designed to walk you through mechanical ventilation step-by-step, in a way that’s clear, visual, and practical.

If you’re ready to truly master the vent and feel confident at the bedside, check out the course.

Volume control or VC mode

• Trigger: VC mode typically uses assist/control (A/C) triggering. As we explained earlier, the ventilator delivers a breath either when the patient initiates one or, if the patient doesn’t, the ventilator will trigger a breath based on the set backup respiratory rate.
• Target: VC mode is flow-targeted, commonly using a decelerating ramp flow pattern.
• Cycle: VC is volume-cycled, meaning the breath ends once the preset tidal volume (TV) has been delivered.

So when ordering VC mode, in addition to the FiO2 and PEEP values, we need to provide the respiratory therapist with the following values:

• The backup RR.
• The TV.
• The Flow curve: square or decelerating.
• The Peak flow rate.

In most cases, RT will, by default, pick a decelerating ramp flow curve and set the peak flow rate; a reasonable starting peak flow rate is between 40-60 L/min.

Take a look at this VC mode screenshot,

Pressure Control (PC) Mode

• Trigger: Like VC mode, PC mode uses assist/control (A/C) triggering, meaning the breath can be triggered either by the patient’s effort or by the ventilator’s set backup respiratory rate if no spontaneous inspiratory effort is detected.
• Target: As the name suggests, PC mode is pressure-targeted. The ventilator delivers a breath by applying a set inspiratory pressure above the PEEP, and adjusts flow as needed to maintain that pressure throughout inspiration.
• Cycle: PC mode is time-cycled—the breath ends when the set inspiratory time has elapsed, regardless of how much volume was delivered.

When ordering PC mode, in addition to the FiO2 and PEEP values, we need to provide the respiratory therapist with the following values:

• Back up RR.
• Pi or inspiratory pressure, this is the pressure that will be added on top of the PEEP during inspiration.
• Ti or inspiratory time, this is the time the inspiratory pressure will be applied for.

   

Pressure support (PS) mode

• Trigger: This mode is patient-triggered only—there’s no backup respiratory rate. That’s why it’s suitable only for awake, spontaneously breathing patients, typically during the weaning phase of mechanical ventilation.
• Target: PS mode is pressure-targeted, similar to PC mode. The ventilator delivers a breath by applying a set inspiratory pressure above PEEP to assist the patient’s spontaneous effort.
• Cycle: PS mode is flow-cycled. The breath ends when the inspiratory flow decreases to a preset threshold, usually 25% of the peak inspiratory flow.

When ordering PS mode, in addition to FiO2 and PEEP values, we provide the respiratory therapist with the following values:

• Inspiratory pressure. In this mode, it’s called Pressure support.
• The flow cycle percentage is typically 25%.

There’s no backup RR because it only uses the patient’s trigger.

Concept (8): No Mode is perfect!

Each mode has its advantages and limitations.

Key Differences in Volume, Pressure, and Support Modes:

• Volume Control (VC):
  You’re guaranteed a set tidal volume, but there’s no cap on peak inspiratory pressure (PIP)—it can rise significantly if the lungs are stiff or airways are tight.
• Pressure Control (PC):
  The PIP is controlled and capped at the set level, but the tidal volume will vary based on the patient’s lung compliance and airway resistance.
• Pressure Support (PS):
  Similar to PC, PIP is limited by the set pressure support level, but tidal volume is not fixed. This mode is patient-triggered and commonly used for weaning.

How about if I take the good stuff from each mode? If I take the set tidal volume from VC mode and the controlled inspiratory pressure from PC mode? Well—that’s exactly how PRVC (Pressure-Regulated Volume Control) was born!

In PRVC, you set the tidal volume you want delivered along with the maximum pressure limit—this acts as a safety cap, not the actual pressure used in each breath.

Here’s how it works:
The ventilator adjusts the inspiratory pressure breath-to-breath to deliver the set tidal volume, while keeping the pressure as low as possible.

If the patient’s lung compliance worsens (like in ARDS), the ventilator will increase the pressure trying to maintain the tidal volume—but only up to the set pressure limit.
If compliance improves, the ventilator will lower the pressure accordingly.

If the pressure needed to deliver the tidal volume exceeds the set limit, the ventilator won’t go higher—it will under-deliver the volume and often trigger a low tidal volume alarm. That’s why choosing a reasonable pressure limit is important, especially in patients with stiff lungs.

Some ventilators also require or allow you to set an inspiratory time (Ti) in PRVC mode. If used, Ti helps shape how long the inspiratory pressure is applied. A longer Ti can help improve alveolar recruitment and oxygenation in patients with stiff lungs, while a shorter Ti may be needed in patients with obstructive lung disease to prevent air trapping.

So, in addition to FiO₂ and PEEP, the following parameters are typically set in PRVC:

• Backup respiratory rate, since it uses an A/C trigger.
• Tidal volume, because it’s volume-cycled.
• Maximum pressure limit, as a safety guard to prevent barotrauma.
• Inspiratory time (Ti), on some vents, to control the duration of pressure delivery and fine-tune I:E ratio.

Take a look at this ventilator screen (notice this particular ventilator manufacturer calls PRVC mode VC+)

SIMV (Synchronized Intermittent Mandatory Ventilation) is essentially a blend of VC or PC with pressure support. I won’t dive deeper into SIMV here, as I rarely use it in practice today, and there’s no strong clinical justification for choosing it over other modes.

Current evidence does not support the superiority of SIMV, VC, PC, or PRVC over one another in terms of clinical outcomes for patients with acute respiratory failure or other critical care conditions.

The choice of ventilation mode should always be individualized, based on the patient’s clinical status, lung mechanics, and response to therapy! I like PRVC as it may offer advantages in terms of lower peak inspiratory pressures and more stable gas exchange, making it a reasonable first choice among the three modes.

Concept (9): Tuning the Vent (Oxygenation vs. Ventilation)

When managing a ventilated patient, it’s crucial to understand what you’re trying to fix—are you trying to improve oxygenation or ventilation?

These are two distinct goals, and each is managed by adjusting different ventilator settings:

• To improve oxygenation, we focus on increasing FiO₂ and PEEP.
• To improve ventilation ( CO2 removal), we adjust the tidal volume (TV) and respiratory rate (RR).

Knowing which “knob to turn” allows you to make targeted, effective changes based on your patient’s needs—without overcomplicating things.

Hypoxia

I typically start with an FiO₂ of 100% and a PEEP of 10 cmH₂O. From there, I aim to wean the FiO₂ as quickly as possible, targeting ≤60% to minimize the risk of oxygen toxicity.

I avoid reducing PEEP until FiO₂ is down to 60% or less. If I can’t lower FiO₂ safely, I’ll consider increasing PEEP—usually in increments of 2–4 cmH₂O—to improve oxygenation. But keep in mind: raising PEEP will also increase peak inspiratory pressure (PIP).

For refractory hypoxemia, there are additional advanced strategies—such as recruitment maneuvers, paralytics, inhaled pulmonary vasodilators, and ECMO—which are beyond the scope of this video and should be managed by an intensivist.

And don’t forget: in patients with ARDS, early prone positioning is a key intervention that can significantly improve oxygenation.

Ventilation

When it comes to improving ventilation (i.e., CO₂ removal), the two main variables we adjust are the tidal volume (TV) and the respiratory rate (RR).

✅ Key Principles:

• Always use predicted body weight (PBW)—not actual body weight—to calculate tidal volume.
  • In ARDS, we aim for a lung-protective strategy:
    ➤ 6 mL/kg PBW
  • In most other conditions, a range of 6–8 mL/kg PBW is acceptable.
• If more ventilation is needed, it’s generally safer to increase the RR rather than the tidal volume to reduce the risk of volutrauma, but remember that the higher the RR, the shorter the respiratory cycle, which affects the I:E ratio.

🛠 How Tidal Volume Is Set (or Adjusted) in Different Modes:

• In VC and PRVC modes, the tidal volume is set directly and can be easily adjusted.
• In PC and PS modes, tidal volume is not set—instead, it depends on:
  • The pressure gradient between PIP and PEEP.
  • The inspiratory time.

📈 In Pressure Control (PC) Mode:

To increase tidal volume:

• Increase the inspiratory pressure (PIP).
• Decrease the PEEP (carefully, as this may affect oxygenation).
• Or do both to widen the pressure gradient.
• Increase inspiratory time (Ti) to allow more time for lung filling.

📈 In Pressure Support (PS) Mode:

It’s the same concept, just different terminology:

• The “pressure support” setting is analogous to the “inspiratory pressure” in PC mode.
• Inspiratory time is not directly set, but can be adjusted by modifying the flow cycle threshold:
  • Lowering the flow cycle percentage prolongs inspiratory time.
  • Raising it shortens inspiratory time.

Let’s wrap it up here! I hope this post gave you a strong foundation in mechanical ventilation and helped make things clearer and more practical for your clinical work.

If you’re ready to take it to the next level and truly master topics like PIP, mean airway pressure, rise time, gas trapping, and auto-PEEP, inverse ratio ventilation, as well as how to assess weaning readiness and perform a proper weaning trial—then check out my full mechanical ventilation course here. It’s packed with real-world explanations, visuals, and tips I’ve gathered over years of hospitalist practice. You’ll find the link below—I’d love to have you in the course!

Introduction

There are three key ingredients to ensure accurate BP measurement at home:

• Choosing the right time.
• Mastering the right technique.
• Using the right device.

Choosing the right time.

The short answer: There’s no single perfect time—but there are best practices.

You can check your blood pressure at different times throughout the day, and I often encourage my patients to do so. However, for the most accurate reading, avoiding certain activities beforehand is crucial.

Tips for Accurate Blood Pressure Readings (Per ACC & AHA Guidelines):

✅ Avoid caffeine, alcohol, exercise, and smoking for at least 30 minutes before measuring.
✅ Sit quietly for 5 minutes before taking your reading—keep your feet flat on the floor and your back supported.
✅ Empty your bladder beforehand, as a full bladder can raise your blood pressure.

These simple steps help eliminate factors that can falsely raise your blood pressure.

What is the technique to check your blood pressure?

When it comes to accuracy, upper-arm monitors are the preferred choice. The American Heart Association (AHA) recommends arm cuff-based devices over wrist monitors because they tend to provide more reliable readings. Research has shown that upper-arm measurements align more closely with ambulatory blood pressure monitoring (ABPM)—the gold standard for assessing blood pressure.

Key Tips for Accurate Blood Pressure Readings:

✔ Use an upper-arm monitor for the most precise measurements.
✔ Keep your arm at heart level while measuring—this applies whether you’re using an upper-arm or wrist monitor.
✔ Choose the right cuff size to ensure accuracy.

Blood Pressure Cuff Sizes:

📏 Small Adult Cuff
📏 Adult Cuff
📏 Large Adult Cuff
📏 Adult Thigh Cuff

Selecting the correct cuff size is crucial—a cuff that’s too small or too large can lead to inaccurate readings. Always check the manufacturer’s sizing guide to find the best fit for your arm.

Choosing the Right Blood Pressure Cuff Size

Selecting the correct cuff size is essential for accurate blood pressure readings. The American Heart Association (AHA) recommends choosing a cuff based on your mid-arm circumference:

📏 Small Adult Cuff → 22-26 cm
📏 Adult Cuff → 27-34 cm
📏 Large Adult Cuff → 35-44 cm
📏 Adult Thigh Cuff → 45-52 cm

Why Cuff Size Matters

Using the wrong cuff size can lead to significant inaccuracies:
❌ Too small? May produce falsely high blood pressure readings.
❌ Too large? Can result in falsely low readings.

How to Ensure Accuracy

For precise measurements, choose a cuff with an inflatable bladder that spans approximately 80% of your arm circumference.

🔎 What is a cuff bladder?
It’s the inflatable chamber inside the blood pressure cuff that, when filled with air, compresses the artery to measure blood pressure accurately.

Using the right cuff improves accuracy and ensures reliable blood pressure monitoring at home.

Which Blood Pressure Monitor Should You Buy?

The American College of Cardiology (ACC) and the American Heart Association (AHA) recommend the following automated, validated blood pressure monitors for home use:

✅ Omron 10 Series BP7450 (HEM-7342T-Z)
✅ Omron Platinum BP5450 (HEM-7343T-Z)
✅ Omron M6 Comfort
✅ Withings BP-800

(I have no financial ties to these manufacturers.)

These models are known for their accuracy and ease of use, making them great choices for home blood pressure monitoring. However, even the best device won’t provide reliable results unless you follow proper measurement techniques.