Shaswat Ayurveda

10/11/2025

09/11/2025

Arterial and venous blood gases (ABGs and VBGs, respectively) help determine acid-base status, gas exchange, O₂ consumption, and electrolyte levels. Most of my patients in the OR and ICU have arterial lines for ABGs, but once these invasive monitors are removed, can VBGs still be helpful? 🤔

First, one must understand the path of blood flow and some basic physiology. Venous blood taken from the internal jugular vein via a central line will have a lower O₂ content because it drains the highly metabolically active brain, and therefore may not accurately represent the whole body. Peripheral VBGs can also be influenced by local factors, such as tourniquet application, which may alter pH, pCO₂, and pO₂ values. 😷

Arterial blood delivers oxygen to tissues; venous blood carries back CO₂, H⁺, and metabolic waste. If the venous end looks good, the arterial side is usually reassuring. For example, if a venous pH is 7.33 after tissue metabolism, I can expect a near-normal arterial pH. Similarly, a venous pCO₂ of 47 mmHg and a normal lactate typically indicate normal arterial counterparts; however, there are exceptions, such as cyanide toxicity, which can produce falsely reassuring venous pO₂ values. 💉

The evidence found that VBGs strongly correlate with ABGs for pH and bicarbonate (venous pH ≈ 0.04 lower, HCO₃⁻ ≈ 1 mEq/L higher), while pCO₂ agreement is variable, and pO₂ predictably differs due to oxygen extraction. Central venous samples can estimate ScvO₂ as a surrogate for mixed venous saturation (SvO₂) and allow calculation of the pCO₂ gap, a useful marker of cardiac output and perfusion. A gap greater than 6 mmHg suggests impaired flow or persistent shock, even when lactate levels normalize. 📈

Assuming the values for noninvasive SpO2 have been corroborated with an ABG beforehand, one can do a lot with a pulse ox and VBG! 🩸

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09/11/2025

09/11/2025

❤️ WHEN THE LEFT HEART STRUGGLES: THE CHAIN REACTION FROM HEART TO KIDNEYS 💔🩸🫁

This visual paints a dramatic but fascinating story — the journey of left-sided heart failure and how its ripple effects reach all the way to your lungs and kidneys. Imagine your heart as a powerful pump that never rests — when one side weakens, the entire circulation feels the strain. Let’s break it down 👇

🔹 1. Mechanism of Left Heart Failure:
At the top, you’ll see the two main villains — systolic and diastolic dysfunction.

🫀 Systolic Dysfunction happens when the heart muscle loses its squeeze. A weak left ventricle can’t eject enough blood during contraction, leading to volume overload and a stretched, dilated chamber — like a balloon that’s been overinflated too many times. This is called eccentric hypertrophy.

💢 Diastolic Dysfunction, on the other hand, is all about stiffness. Chronic high blood pressure or aortic stenosis thickens the heart walls, making it tough for the ventricle to relax and fill. This “pressure overload” creates a bulky, rigid heart — concentric hypertrophy — that can’t hold enough blood.

Both lead to the same tragic end: a heart that can’t keep up with the body’s demand.

🔹 2. The Domino Effect – How the Lungs and Kidneys Suffer:
When the left ventricle fails, blood backs up into the left atrium and then into the lungs. The pulmonary vessels become congested, increasing pressure and fluid buildup — that’s why patients feel short of breath, fatigued, and may even cough up frothy sputum.

As the pressure climbs, the right ventricle struggles to push blood into the overloaded lungs. Over time, it also weakens, causing right-sided failure — now, the congestion extends backward into the systemic circulation.

🔹 3. The Kidney Connection – Cardiorenal Syndrome:
Poor forward flow from the heart means less blood reaches the kidneys. They interpret this as low volume and respond by retaining salt and water, worsening fluid overload. Meanwhile, backward pressure from the venous side compresses the kidneys, impairing filtration — a double hit that accelerates kidney dysfunction.

🩸 The result? Vasoconstriction, edema, hypertension, and further cardiac stress — a vicious cycle between heart and kidney known as cardiorenal syndrome.

💬 In essence: The left heart’s failure is not isolated — it’s a system-wide crisis. This visual reminds us that when one organ falters, others follow — and early intervention in heart failure can save not just the heart, but the lungs and kidneys too.

Disclaimer: Image Credit to the Rightful Owner.