RSI Drug Doses (Adult)
Rapid Sequence Intubation — weight-based dose calculator. Always confirm with local formulary.
Detailed Guide Coming Soon
We're working on a comprehensive educational guide for the RSI Drug Dose Calculator (Adult) in your language. The content below is shown in English.
What is RSI Drug Dose Calculator (Adult)?
▾
Imagine you are an emergency room nurse, a paramedic on a bumpy ambulance ride, or a medical student on your first intensive care rotation. Suddenly, a patient arrives who cannot breathe on their own. You have only seconds to secure their airway by placing a breathing tube. This high-stakes, rapid-fire procedure is called Rapid Sequence Intubation, or RSI. To do it safely, you have to temporarily knock the patient out (induction) and completely paralyze their muscles (neuromuscular blockade) at the exact same time. This prevents them from gagging or breathing fluid into their lungs, making the procedure as smooth and safe as possible. But here is the catch: there is absolutely zero room for guesswork. Emergency medications are incredibly powerful, and their doses must be tailored perfectly to the patient's weight and medical background. Give too little, and the patient might wake up or fight the breathing tube. Give too much, and their blood pressure could crash dangerously. That is where our RSI Drug Dose Calculator comes in. It acts like a trusted colleague standing right next to you, instantly doing the heavy lifting of the math so you can focus 100% of your attention on the patient. In daily clinical life, this tool is a lifesaver—literally. It helps healthcare providers quickly and confidently double-check emergency drug volumes during those chaotic, adrenaline-fueled moments. Whether you are studying for your paramedic boards, brushing up on ICU protocols, or standing at the bedside in a busy ER, having these precise, weight-based calculations at your fingertips ensures you deliver the safest care possible when every second counts.
DigiCalcs delivers precision-engineered tools for engineers and STEM professionals.
Formula
▾
Ketamine dose = 1–2 mg/kg IV; Propofol dose = 1.5–2 mg/kg IV; Succinylcholine dose = 1.5 mg/kg IV; Rocuronium dose = 1.2 mg/kg IV; Fentanyl pretreatment = 3 mcg/kg IVVariable Legend
▾
| Symbol | Vārds | Vienība | Apraksts |
|---|---|---|---|
| W | Patient weight | kg | Patient's actual or estimated weight in kilograms. This is the foundation of every single calculation, ensuring the medicine matches their body size perfectly. |
| D_ind | Induction agent dose | mg/kg | Sedative dose in milligrams per kilogram. This determines how much sleep medicine is needed to safely knock the patient out. |
| D_nmb | NMBA dose | mg/kg | Muscle relaxant dose in milligrams per kilogram. This calculates the exact amount of paralytic needed to stop all muscle movement so the tube can be placed easily. |
| D_pre | Fentanyl pretreatment dose | mcg/kg | Pretreatment pain medicine dose in micrograms per kilogram. Usually fentanyl, this helps prevent sudden spikes in blood pressure or brain pressure. |
| D_rev | Sugammadex reversal dose | mg/kg | Rescue reversal dose in milligrams per kilogram. This is the weight-based dose of sugammadex, used to instantly reverse rocuronium if you need to wake the patient up in an emergency. |
How to RSI Drug Dose Calculator (Adult)
▾
- 1Step 1 — Get Your Gear Ready: Lay out your tools (breathing tubes, laryngoscope, suction, and backup airway gear), double-check your IV lines, and make sure the patient's monitors are humming along nicely.
- 2Step 2 — Fill the Oxygen Tank: Give the patient 100% oxygen through a tight mask for at least 3 minutes. Think of this as filling up their internal oxygen reserve tank so they can safely tolerate a brief period of not breathing.
- 3Step 3 — Ease the Shock (Optional): Administer a quick dose of fentanyl (3 mcg/kg) about 3 minutes before the main event. This keeps their heart rate and brain pressure from spiking when the breathing tube goes in.
- 4Step 4 — Send Them to Sleep: Push your chosen sedative (like ketamine or propofol) quickly into the IV. This knocks the patient out fast and comfortably.
- 5Step 5 — Relax the Muscles: Immediately follow up with your muscle relaxant (succinylcholine or rocuronium). Watch for tiny muscle twitches to stop, showing the paralytic is working.
- 6Step 6 — Place the Tube: Gently and quickly insert the breathing tube into the windpipe. Double-check that it is in the perfect spot by watching the carbon dioxide monitor turn yellow.
- 7Step 7 — Keep Them Comfortable: Secure the tube, hook them up to the ventilator, and start a steady drip of pain and sleep medicine to keep them resting peacefully.
Worked Examples
▾
Ketamine is a great choice here because it keeps blood pressure stable without raising brain pressure, while succinylcholine acts incredibly fast.
Let's break down the math for our 70 kg patient: Fentanyl is 3 mcg/kg, so 3 × 70 = 210 mcg. Ketamine is 1 to 2 mg/kg, giving us a range of 70 to 140 mg. Succinylcholine is 1.5 mg/kg, which equals 105 mg. If we couldn't use succinylcholine, we would use rocuronium at 1.2 mg/kg, which is 84 mg.
Ketamine is our hero here because it actually helps support a crashing blood pressure, unlike propofol which can cause it to drop further.
For an 80 kg patient in shock, we avoid propofol because it relaxes blood vessels too much. Instead, we use Ketamine: 1 to 2 mg/kg × 80 = 80 to 160 mg. For the paralytic, we calculate Succinylcholine at 1.5 mg/kg × 80 = 120 mg.
Succinylcholine can cause a dangerous spike in blood potassium for patients with crush injuries, making rocuronium the much safer choice.
For our 60 kg patient, we swap succinylcholine for rocuronium at 1.2 mg/kg × 60 = 72 mg. If we need to reverse this paralytic immediately, we have sugammadex ready at 16 mg/kg × 60 = 960 mg. Our sedative Ketamine is 1 to 2 mg/kg × 60 = 60 to 120 mg.
Ketamine does double duty here—it puts the patient to sleep and also relaxes their tight airways, making it perfect for severe asthma.
For a 90 kg patient struggling with asthma, Ketamine is dosed at 1 to 2 mg/kg × 90 = 90 to 180 mg. Succinylcholine is calculated at 1.5 mg/kg × 90 = 135 mg to quickly paralyze the vocal cords for easy tube placement.
Real-World Applications
▾
Emergency room teams rapidly securing airways for patients who have suffered severe trauma or cardiac arrest.
Paramedics and flight nurses performing life-saving intubations in the back of a moving ambulance or helicopter.
Anesthesiologists preparing patients for emergency surgery when they haven't had time to fast beforehand.
Intensive care units managing patients whose lungs are failing due to severe pneumonia or COVID-19.
Transport teams securing a patient's breathing before moving them safely between hospitals.
Special Cases
▾
Traumatic Brain Injury (TBI)
When a patient has a severe head injury, their brain is already under immense pressure. Inserting a breathing tube can cause a sudden spike in blood pressure, which can worsen brain swelling. In these cases, doctors often use a pre-treatment like fentanyl to blunt this reflex. They also carefully choose sedatives like etomidate or low-dose ketamine to keep blood flow to the brain perfectly balanced.
Shock and Low Blood Pressure
If a patient's blood pressure is already bottoming out, standard doses of sedatives can cause a dangerous cardiovascular crash. In these critical moments, medical teams will often cut the sedative dose in half (or even more) while keeping the paralytic dose high. This ensures the patient is still fully paralyzed for the procedure without dropping their blood pressure to zero.
Extreme Body Sizes (Obesity)
When calculating doses for very large individuals, things get a bit tricky. Some drugs distribute into body fat, while others stay mostly in lean muscle. For paralytics like succinylcholine, we usually calculate the dose using the patient's actual weight. But for sedatives like propofol, we often use their ideal body weight to avoid giving a dangerous overdose.
Pregnancy
Pregnant patients are always considered to have a 'full stomach' because of the physical pressure on their digestive system. This means they are at a very high risk for inhaling stomach contents during intubation. The drug doses must be calculated rapidly and precisely, and the procedure must be done as quickly as possible to protect both mom and baby.
Pediatric Patients
While this calculator is designed for adults, it is important to remember that kids are not just small adults! Their metabolisms are different, their airways are shaped differently, and their drug doses must be calculated using highly specific pediatric guidelines. Always use a dedicated pediatric calculator for children to ensure their safety.
RSI Drug Doses by Weight
▾
| Drug | Dose | Onset | Duration | Notes |
|---|---|---|---|---|
| Ketamine | 1–2 mg/kg IV | 45–60 sec | 10–20 min | Great for low blood pressure or asthma. |
| Propofol | 1.5–2 mg/kg IV | 30–45 sec | 5–10 min | Avoid if blood pressure is already low. |
| Etomidate | 0.3 mg/kg IV | 30–60 sec | 10–15 min | Very gentle on the heart and blood pressure. |
| Succinylcholine | 1.5 mg/kg IV | 45–60 sec | 10–15 min | Super fast, but watch out for high potassium. |
| Rocuronium | 1.2 mg/kg IV | 60–90 sec | 45–70 min | Long-acting; can be reversed with Sugammadex. |
| Fentanyl (pre-Rx) | 3 mcg/kg IV | ~3 min | 30–60 min | Helps keep heart rate and brain pressure stable. |
| Sugammadex (reversal) | 16 mg/kg IV | 3 min | Full reversal | Emergency off-switch for Rocuronium. |
Frequently Asked Questions
▾
What exactly is RSI and why do we use these specific medications?
Rapid Sequence Intubation (RSI) is the gold-standard method for quickly taking control of a patient's breathing when they are at risk of inhaling stomach contents. We use a fast-acting sleep medicine (induction agent) followed immediately by a muscle relaxant (paralytic) to make the patient unconscious and perfectly still within seconds. This rapid-fire sequence minimises the time the airway is unprotected, reducing the risk of dangerous aspiration. Common sleep medicines include Etomidate (great for keeping blood pressure stable) and Ketamine (excellent for asthma and shock), while Propofol is saved for patients with stable hearts.
What are the main muscle relaxants used and how are they dosed?
The two heavy hitters in emergency paralysis are Succinylcholine and Rocuronium. Succinylcholine is dosed at 1 to 1.5 mg/kg and is famous for being the fastest-acting paralytic, wearing off in just 10 minutes, though it can't be used in patients with high potassium or major crush injuries. Rocuronium is dosed higher for RSI at 1.2 mg/kg to match that lightning-fast speed, lasting about an hour. The beauty of rocuronium is that it can be instantly reversed with Sugammadex, making it an incredibly popular and safe choice in modern medicine.
How do we choose the right sleep medicine for an adult patient?
Choosing the right sedative is all about looking at the patient's heart and lungs. Propofol (1.5 to 2.5 mg/kg) is wonderful for stable patients but can cause blood pressure to plummet, so we avoid it in shock. Etomidate (0.3 mg/kg) is the go-to for heart stability, though it can temporarily suppress adrenal hormones. Ketamine (1 to 2 mg/kg) is a favorite in emergency medicine because it supports blood pressure and relaxes tight airways, making it perfect for trauma, shock, and severe asthma attacks.
How should we adjust these doses for patients carrying extra weight?
When treating obese patients, we have to be smart about how drugs distribute in the body. For sleep medicines like propofol, we usually calculate the dose using their 'ideal body weight' based on their height, which prevents them from getting too sleepy for too long. However, for paralytics like succinylcholine, we dose based on their 'total body weight' because these drugs need to reach all the muscle tissue. Getting this balance right keeps the procedure safe and effective.
Do we need to change the doses if a patient has kidney or liver problems?
Yes, organ health plays a big role in how our bodies process these powerful medications. For instance, succinylcholine can cause a dangerous release of potassium into the blood, so we avoid it if a patient already has kidney failure and high potassium levels. Rocuronium is processed by the liver and kidneys, so its paralyzing effects can last much longer in patients with organ failure. In these cases, we might reduce the doses or prepare for a longer recovery time.
Common Mistakes to Avoid
▾
- !Waiting too long between the sleep medicine and the paralytic, which defeats the whole purpose of a 'rapid' sequence and leaves the patient awake while unable to breathe.
- !Using propofol on a patient who already has dangerously low blood pressure, which can cause their heart to stop during the procedure.
- !Forgetting to check if the patient has high potassium or a recent crush injury before giving succinylcholine, which can trigger a life-threatening heart rhythm.
- !Skipping the pre-oxygenation step, which leaves you with zero safety margin if the breathing tube is difficult to place.
- !Not having a backup plan or a rescue drug like Sugammadex ready in case you cannot get the breathing tube in on the first try.
- !Neglecting to confirm the tube is in the lungs using a carbon dioxide monitor, which can lead to a fatal esophageal placement.
Pro Tip
Always remember the 'double-check' rule: have a colleague read the calculated drug volumes out loud before you draw them up. In a chaotic emergency room, a second pair of eyes is your best defense against dosing errors.
Did you know?
Did you know that the paralytics we use today are modern cousins of curare? Curare is a plant-based poison that South American indigenous hunters used on the tips of their blowdarts for centuries to paralyze prey. Today, scientists have refined those same principles to save lives in operating rooms every single day!
References
Saņemiet iknedēļas matemātikas padomus
Pievienojieties 12 000+ abonentiem, kuri katru nedēļu saņem kalkulatora padomus.