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Acute Respiratory Failure-II

Acute Respiratory Failure-II

Type I Respiratory Failure, or hypoxemic respiratory failure, occurs when the partial pressure of oxygen (PaO2) in arterial blood falls below 60 mmHg while breathing room air without a corresponding increase in arterial carbon dioxide levels (PaCO2). This condition highlights a significant impairment in the lungs' capacity to oxygenate the blood.
The underlying physiological abnormalities that contribute to hypoxemic respiratory failure include:

Hypoxia

Hypoxia

Hypoxia is a medical condition characterized by an inadequate oxygen supply to body tissues. It typically manifests as a bluish discoloration of the skin and mucosae, especially in fair-skinned individuals, when hemoglobin (Hb) saturation drops below 75%.
Types of Hypoxia
There are four primary types of hypoxia, each resulting from a different cause:
1. Anemic hypoxia: This type occurs due to insufficient oxygen delivery caused by a lack of red blood cells (RBCs) or RBCs with abnormal or...

Acute Respiratory Failure-III

Acute Respiratory Failure-III

Hypercapnic respiratory failure, also known as Type 2 or ventilatory respiratory failure, is a severe condition characterized by the body's inability to effectively remove carbon dioxide (CO2) from the bloodstream. It leads to an arterial CO2 pressure (PaCO2) exceeding 45 mmHg and a blood pH above 7.35. This situation indicates that the body's ventilatory demand, or the ventilation needed to maintain normal PaCO2 levels, surpasses its supply or the maximum gas flow achievable without causing...

Acute Respiratory Failure-I

Acute Respiratory Failure-I

Acute respiratory failure is a condition characterized by the inability of the lungs to perform their primary function: gas exchange. This failure leads to insufficient oxygen levels (hypoxemia) in the blood, elevated carbon dioxide levels (hypercapnia), or both, causing critical impairment in organ function.
Definition: It is defined by specific criteria based on blood gas measurements. Hypoxemia happens when the partial pressure of oxygen (PaO2) falls below 60 mmHg. At the same time,...

Acute Respiratory Failure-IV

Acute Respiratory Failure-IV

Respiratory failure can manifest suddenly or gradually, characterized by a rapid decline in PaO2 and a rapid rise in PaCO2. This situation indicates a severe respiratory problem that may quickly become a life-threatening emergency. One of the early signs of hypoxemic Acute Respiratory Failure (ARF) is a change in mental status due to the brain's sensitivity to oxygen levels and changes in acid-base balance. Symptoms such as restlessness, confusion, and agitation suggest inadequate oxygen...

Atelectasis II: Pathophysiology

Atelectasis II: Pathophysiology

Atelectasis develops when alveoli lose their air and collapse inward. Because lung tissue is naturally elastic, these air sacs shrink rather than remaining open. Collapsed alveoli are no longer ventilated, reducing their role in gas exchange. Blood flow may continue in these regions, creating a ventilation–perfusion mismatch. Clinical findings include decreased breath sounds, dullness to percussion, reduced chest expansion, and decreased tactile fremitus as sound transmission through collapsed...

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Related Experiment Video

Updated: Jun 2, 2026

Delivery of In Vivo Acute Intermittent Hypoxia in Neonatal Rodents to Prime Subventricular Zone-derived Neural Progenitor Cell Cultures

Delivery of In Vivo Acute Intermittent Hypoxia in Neonatal Rodents to Prime Subventricular Zone-derived Neural Progenitor Cell Cultures

Published on: November 2, 2015

[Refractory hypoxia].

P Cuchard¹, P Guillemin

¹Centre de Traitement et de Réadaptation (CRT), Hôpital Riviera, Site de Mottex, Blonay.

|April 29, 2011

Summary

This summary is machine-generated.

An elderly smoker with heart and lung issues developed severe hypoxia unresponsive to oxygen. Platypnea-orthodeoxia syndrome caused by an inter-atrial shunt was diagnosed.

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Area of Science:

Cardiology
Pulmonology
Geriatric Medicine

Background:

An 85-year-old smoker with cardiac and pulmonary comorbidities presented with refractory hypoxia.
Initial clinical presentation suggested cardiac failure or pneumonia as the cause of respiratory insufficiency.

Observation:

Despite optimal treatment for presumed cardiac failure and pneumonia, the patient remained severely hypoxic with minimal symptoms.
Hypoxia did not improve with oxygen therapy and worsened in the sitting position (platypnea-orthodeoxia).

Findings:

The clinical presentation and positional worsening of oxygen saturation indicated platypnea-orthodeoxia syndrome.
Cardiac ultrasound with contrast confirmed a significant inter-atrial shunt, establishing the cause of the right-to-left cardiac shunt.
The patient declined recommended shunt closure treatment.

Implications:

This case highlights the importance of considering platypnea-orthodeoxia syndrome in elderly patients with unexplained refractory hypoxia, especially those with comorbidities.
Positional changes in oxygen saturation can be a critical diagnostic clue for intracardiac shunts.
Effective management requires accurate diagnosis and patient-centered decision-making regarding treatment options.