Question

Which of the following patients are at most risk for tachypnea? (Select all that apply.) A. Patient just admitted with four rib fractures B. Woman who is 9 months' pregnant C. A patient admitted with hypothermia D. Postoperative patient waking from general anesthesia E. Three-pack-per-day smoker with pneumonia

Short answer

Patients A (with rib fractures), B (who is 9 months' pregnant), and E (a heavy smoker with pneumonia) are at most risk for tachypnea.

Step-by-step solution

Understanding Tachypnea

Tachypnea refers to an abnormally rapid breathing rate. Conditions that lead to hypoxemia (low oxygen levels in the blood), hypercapnia (high carbon dioxide levels), or increased metabolic demands can cause tachypnea.

Evaluating Patients' Conditions

To determine which patients are at most risk for tachypnea, we need to evaluate each patient's condition and consider if it might lead to rapid breathing. Assess whether each condition typically affects breathing rates and how.

Identifying High-Risk Conditions for Tachypnea

Patients with rib fractures may breathe quicker to minimize pain, leading to tachypnea. During late pregnancy, the diaphragm is elevated and lung capacity decreased, which may result in tachypnea. Hypothermia typically slows down metabolism and bodily functions, hence lower risk for tachypnea. General anesthesia might suppress respiration initially, but as it wears off, normal or slightly increased breathing rate returns unless complications occur. Pneumonia, especially in heavy smokers, impairs gas exchange and typically results in tachypnea.

Selecting the Correct Answers

Evaluating the given conditions against known causes of tachypnea, patients A, B, and E have conditions that could clearly increase their risk for tachypnea. Patients C and D do not have conditions that typically lead to sustained rapid breathing rates.

Key concepts

Abnormal Breathing Rate

When discussing abnormal breathing, we're generally exploring patterns that deviate from the regular, controlled breaths usually around 12 to 20 per minute for a healthy adult.

Abnormal breathing rates can manifest as either too fast (tachypnea) or too slow (bradypnea). Tachypnea, specifically, is clinically defined as a respiratory rate over 20 breaths per minute and is often an adaptive response to meet increased oxygen demand or to expel more carbon dioxide.

Conditions such as lung damage from injury, diseases like pneumonia, or physiological changes during pregnancy can force the respiratory system to work harder. For example, in our exercise, patients with rib fractures or heavy smokers with pneumonia are more prone to developing tachypnea because their conditions directly affect the lungs' ability to perform optimally, compelling them to breathe faster in an attempt to meet the metabolic demands of the body.

Hypoxemia

Hypoxemia occurs when there's a deficiency of oxygen in the blood, a critical issue since oxygen is essential for the survival of all tissues in the body.

Commonly measured by the amount of oxygen bound to hemoglobin in the blood, hypoxemia can trigger compensatory mechanisms such as tachypnea. The body instinctively increases the breathing rate to draw in more oxygen to counteract the deficit.

For instance, a patient with pneumonia might experience hypoxemia due to impaired gas exchange in the lungs. The body responds by accelerating the breathing pace, which sometimes leads to tachypnea, as we see in patient E from the exercise. Understanding how hypoxemia affects the body helps us comprehend why certain medical conditions lead to increased breathing rates.

Hypercapnia

Hypercapnia is characterized by an excess of carbon dioxide (CO₂) in the bloodstream, typically caused by inadequate respiration. CO₂ is a byproduct of the body's metabolism and is normally expelled when we exhale.

If the body cannot remove CO₂ efficiently—due to lung diseases, airway obstructions, or neuromuscular conditions—it may lead to hypercapnia. The body responds by trying to increase respiratory rate and depth to expel more CO₂, potentially causing tachypnea.

In our exercise scenarios, a patient with severe pneumonia who is a heavy smoker, like patient E, could struggle with hypercapnia since the gas exchange in their lungs is compromised. This underlines the importance of performing a detailed assessment of patients’ respiratory conditions to determine their risk for abnormal breathing rates.