Continuing Education Activity

Tachypnea is defined as a breathing rate that is higher than normal. This symptom is seen in both the physiologic state and as a symptom of pathology. The breathing rate is periodically assessed by a triage team and the treating clinician, depending on the acuity of the chief complaint. Based on the severity of the increase in the breathing rate, the clinician may observe tachypnea without measuring the rate and can note if accessory muscles are used. If the patient has pre-existing health conditions, tachypnea is physiologic versus a healthy patient who suddenly develops tachypnea or develops tachypnea following a traumatic incident. The context of the tachypnea directs the clinician to consider the physical exam and medical management. When tachypnea is measured, this value is referred to as respiratory rate.

Through engaging in this course, clinicians gain invaluable insights into the comprehensive evaluation and management of tachypnea, underscoring the collaborative efforts of an interprofessional healthcare team. By harnessing the expertise of professionals across various disciplines, including family medicine, emergency medicine, and internal medicine, clinicians are better equipped to navigate the complexities of diagnosing and treating tachypnea effectively. This collaborative approach not only enhances the depth and accuracy of the diagnostic process but also fosters a holistic understanding of the patient's condition, thereby optimizing treatment outcomes.

Objectives:

• Identify the characteristic symptoms and clinical presentations associated with tachypnea, including variations in breathing rates and the utilization of accessory muscles, to facilitate prompt recognition and diagnosis in clinical settings.

• Differentiate between physiologic tachypnea, often observed in response to exertion or anxiety, and pathological tachypnea, indicative of underlying health conditions, such as respiratory distress or metabolic acidosis, to guide appropriate treatment interventions.

• Screen patients presenting with tachypnea for potential underlying causes, utilizing comprehensive history-taking, physical examination, and diagnostic tests to elucidate contributing factors and inform targeted management strategies.

• Collaborate with an interprofessional healthcare team to develop comprehensive care plans for patients with tachypnea, integrating input from specialists, primary care providers, respiratory therapists, and other stakeholders to optimize treatment efficacy and promote holistic patient-centered care.

Introduction

Tachypnea refers to rapid breathing, typically defined as a symptom and a focused problem within a medical evaluation. The normal breathing rate for an average adult is 12 to 20 breaths per minute. The number of breaths per minute in children and newborns is higher than the resting rate in adults.[1] (Considering that the demand for oxygen and carbon dioxide (CO2) varies based on size contextualizes these different breathing rates.) The term tachypnea is sometimes confused with tachycardia, which defines a high heart rate. Heart rate relates to cardiac output, whereas breathing relates to ventilation, further contextualizing tachypnea.

As a symptom, tachypnea is caused by several medical conditions, including acute and chronic. This learning activity aims to consider the etiologies, pathophysiology, and general approach to medical evaluation, incorporating the results of recent studies on manual and technological monitoring. Breathing rate is termed respiratory rate when these new and tested methods obtain a measurement. After a measurement is documented, the interprofessional team may refer to a patient as having a high respiratory rate, interchangeably with tachypnea, depending on the clinical presentation. 

Etiology

Physiological

Tachypnea is not always an indicator of underlying pathology. A common example of physiological tachypnea is the body's demand for oxygen during exercise, which causes an increase in respiratory rate. Similarly, when ascending to high-altitude areas, a similar increase in the oxygen demand is seen. Medications for pathological conditions can cause the body to increase respiratory rate. Medications and recreational drugs' adrenergic or stimulating effects could explain a higher respiratory rate. For example, a widely used stimulant, caffeine, causes immediate increases in respiratory rate. Tachypnea is also normal in pregnant women, children, infants, and older adults.

Pathological

Below are some of the common pathological causes of tachypnea:

• Stroke
• Sepsis
• Diabetic ketoacidosis
• Pneumonia
• Carbon monoxide poisoning
• Pulmonary embolism
• Pleural effusion
• Chronic obstructive pulmonary disease 
• Allergic reactions
• Anxiety
• Foreign body aspiration
• Post-status motor vehicle accident [2][3]

Epidemiology

Tachypnea in newborns could indicate underlying pathology within the respiratory system that is apparent after delivery. The condition can result from impaired fetal lung fluid clearance, leading to respiratory distress. Transient tachypnea of the newborn has a higher prevalence in preterm infants. Tachypnea occurs in approximately 1 in 100 preterm infants and about 4 to 6 per 1000 infants.[4][5] Tachypnea in adults is defined as breathing more than 20 breaths per minute. Twelve to 20 breaths per minute is a normal range, defined as a normal respiratory rate.

Pathophysiology

Tachypnea is a term used to define rapid and shallow breathing, not to be confused with hyperventilation, when a patient's breathing is rapid but deep. Both are similar in that both may result from a buildup of CO2 in the lungs, leading to increased CO2 in the blood.[6] This buildup makes the blood acidic, alerting the brain through chemoreceptors in the medulla. In response, the chemoreceptors signal the pulmonary stretch receptors in the lungs to increase the pace to correct the CO2 imbalance to oxygen. In doing so, the blood acidity can return to the normal range. When the imbalance is too rapid, too large, or chronic, this is further defined as an acid-base imbalance in respiratory and renal physiology.

Considering the molecular basis describing the equilibrium of each of these factors reinforces why rapid and shallow breathing might occur: CO₂+H₂O ⇔ H₂CO₃ ⇔ HCO³⁻+H⁺

^{CO2, carbon dioxide; H20, water; H, hydrogen; H2CO3, carbonic acid; HCO3, bicarbonate}

• If too much CO2 is retained, the equilibrium would shift to the right, producing more hydrogen ions and making the blood acidic.
• When breathing is increased, CO2 is exhaled, shifting the equilibrium back to the left and reducing the blood acidity.
• If the acidity cannot be compensated through breathing alone, the kidneys further alkalinize serum by retaining bicarbonate at the tubule level and shifting the equilibrium further to the left.

History and Physical

History

The quality of breathing is assessed via the history of the present illness (if relevant to the chief complaint and when reviewing all systems). Patients may complain of feeling short of breath or unable to get enough air. They may lean forward in a "tripod position" or speak poorly. The feeling can be described as increased breathing, whereas the signs of disequilibrium are defined as cyanosis (peripheral or central), increased work of breathing, or tachypnea. Several terms describe the symptoms of labored breathing, including dyspnea, bradypnea, apnea, acute dyspnea, or chronic dyspnea. However, dyspnea refers specifically to difficulty breathing, and bradypnea refers to slower breathing. On the other hand, patients can present without distress or cease breathing, termed apnea.

Physical Exam

Tachypnea is measured and documented in several ways: by manual counting, monitoring devices, electronic medical records, or a mix of both.[7][8] Tachypnea is also part of the systemic inflammatory response syndrome criteria for sepsis and may differentiate disposition status.[9][10] As such, measurement is important at several points in the visit if a patient is deteriorating, and an initial triage respiratory rate is usually compared to a later measurement when a clinician sees the patient. Patients may have blue-tinged fingers or lips and use accessory or chest muscles to breathe from a lack of oxygen. Infants can present with a blue color in the perioral area, grunting or signs of difficulty breathing, retraction of the chest while breathing, bobbing of the head, and flared nostrils.

Evaluation

Lab Evaluation

Clinicians can evaluate based on oximetry and several lab tests (including but not limited to):

• Arterial blood gases: Estimate oxygen and cCO2 content, which can help determine the pH and metabolic abnormalities. 
• Glucose: A blood sugar can indicate or rule out diabetic ketoacidosis.
• Basic or comprehensive metabolic panel: Electrolyte values determine any influence on respiratory rate (such as in hyperkalemia).
• Complete blood count: Hemoglobin and white blood count levels determine signs of anemia or infection.
• Toxicology screen: A positive screen for amphetamines or urine metanephrines can narrow the differential.[11]

Procedural Evaluation

• Electrocardiogram: This is usually completed 1 or more times for periodic evaluation; for example, if a clinician suspects a pulmonary embolism or atrial fibrillation, this could explain a higher respiratory rate.
• Pulmonary function tests: To evaluate for obstructive or restrictive lung diseases.
• Intubation: Patients with tachypnea could quickly lose their airway, warranting immediate protection.

Imaging Modalities

A chest x-ray can depict any pulmonary causes of tachypnea, such as pneumothorax, cystic fibrosis, or pneumonia. A chest computed tomography scan showing greater detail can indicate other lung pathologies or potential malignancies. Lung ventilation perfusion scans are helpful if signs and symptoms indicate a potential pulmonary embolus or pneumonia but could be considered after risk assessments (ie, Wells Criteria or pulmonary embolism rule-out criteria).[12][13] Ultrasound imaging is useful when evaluating newborns, particularly when differentiating respiratory distress syndrome from transient tachypnea.[14][15][16] Ultrasound is also helpful for quick assessments when suspecting pleural effusion, hemothorax, or pericarditis.[17] 

Treatment / Management

Tachypnea is treated depending on the underlying cause. 

Differentiation by Patient Age

If infants present due to transient tachypnea of the newborn, they receive treatment with extra oxygen and, in some cases, may require some time in the neonatal intensive care unit.[15] In children and adults, a broad differential is important so as not to miss the least considered diagnosis, such as a malignancy.[18] Pathology, such as a urinary tract infection, may not cause tachypnea in a young adult but could increase respiratory rate in an older adult. Recently, COVID-19 caused tachypnea in all age groups, and different treatments were utilized.[19]

Respiratory, Cardiac, Endocrine Causes

Respiratory causes such as asthma or chronic obstructive pulmonary disease are treated with short- or long-term bronchodilators, escalating the use of steroids and adjuncts based on clinical discretion, which should correct the tachypnea. Pneumo- or hemothorax typically needs procedural intervention, and acid-base disturbances are treated through ventilation or medication depending on the cause, such as ingestion of excess alcohol, drugs, etc. Similarly, cardiac events such as myocardial infarction, congestive heart disease, or valvular disorders are treated based on severity, as are endocrine causes such as diabetes, hyperthyroidism, Cushing syndrome, or rare causes such as pheochromocytoma. All bacterial infections are treated by varying antibiotic regimens, and viral infections are treated supportively.[20] If patients have multiple underlying pathologies, these are treated in order of priority. For example, diagnosing a rare brain tumor that causes tachypnea may take several visits, though the tachypnea is treated by oxygen.

Differential Diagnosis

A broad differential diagnosis categorized by each system is essential depending on where the patient presents with tachypnea. For emergency clinicians, undifferentiated patients lead to the most life-threatening diagnoses. In contrast, for critical care clinicians, the diagnosis may be known, and they document the progress of respiratory rate and quality. In contrast, a neurologist may prioritize types of strokes that could most likely lead to acute or chronic tachypnea. As such, by age group, some of the common diagnoses are:

Infants and Children

• Respiratory distress syndrome 
• Transient tachypnea of the newborn 
• Pneumonia
• Asthma

Adults

• Pneumonia 
• Pulmonary embolism 
• Congestive heart failure 

Older Adults

• Chronic obstructive pulmonary disease
• Malignancies
• Congestive heart failure

Across age groups, infections are a common diagnosis, as are psychiatric diseases such as generalized anxiety disorder or panic disorder.

Complications

While tachypnea can result from physiological causes such as exercise, pathologic causes are reason for concern. The complications arising from pathologic causes can worsen patient outcomes. Tachypnea can be a symptom of sepsis or acidosis. Patients with lung problems such as pneumonia, pleural effusion, pulmonary embolism, COPD, asthma, or an allergic reaction also present with tachypnea.[21] Congestive heart failure can also be a cause of tachypnea and, if not managed, can progress to worsening heart failure. Since tachypnea is a symptom, changes in respiratory rate indicate if a patient is improving or deteriorating, and as such, changes in medical management are needed. No direct complication can be traced back to tachypnea alone.

Deterrence and Patient Education

Patients should be reassured that tachypnea may not always indicate a serious medical illness. If driven by anxiety, increasing alarm could further exacerbate the tachypnea. Explaining why the breathing rate is increased and comparing the patient's experience to the measured respiratory rate could educate the patient. Patient education regarding how to prevent further episodes of tachypnea is important (ie, reduce caffeine intake, follow-up with cardiology is needed, or taking a full course of antibiotics should resolve the condition).

Enhancing Healthcare Team Outcomes

The best possible outcomes for patient care involve an integrated and interprofessional team approach that includes consultation when needed. If a patient is tachypneic, the role of the physical exam, imaging, and laboratory values are significant. The patient should not be discharged until the tachypnea has resolved and consultations or referrals occur as deemed necessary. Healthcare professionals should consider any significant complications or comorbidities. The disposition should be carefully determined after appropriate monitoring, given the many diagnoses that cause tachypnea, some less emergent than others. Collaboration, teamwork, and communication are necessary for positive outcomes and prognosis.