When the bacilli are isolated within tubercles and immunity develops, the TB bacilli may remain dormant for months, years, or life. Individuals with dormant TB (also called latent TB)

REACTIVATION TUBERCULOSIS

Also called postprimary TB, reinfection TB, or secondary TB)

Term used to describe the reappearance of TB months or even years after the initial infection has been controlled

Reactivation risk factors:

Malnourished individuals, people in institutional housing, people living in overcrowded conditions, immunosuppressed patients, HIV patients (TB is a leading cause of death in HIV patients), alcohol abuse

DISSEMINATED TUBERCULOSIS

Also called extrapulmonary TB, miliary TB, and tuberculosis—disseminated

Refers to infection from TB bacilli that escape from a tubercle and travel to other sites throughout the body by means of the bloodstream or lymphatic system

Most common location is the apex of the lungs

Other oxygen-rich areas in the body include the regional lymph nodes, kidneys, long bones, genital tract, brain, and meninges

ANATOMIC ALTERATIONS OF THE LUNGS
MODERATE TO SEVERE REACTIVATION TB

Alveolar consolidation

Alveolar-capillary destruction

Caseous tubercles or granulomas

Cavity formation

Fibrosis and secondary calcification of the lung parenchyma

Distortion and dilation of the bronchi

Increased bronchial airway secretions

ETIOLOGY AND EPIDEMIOLOGY

TB is one of the oldest diseases known

According to the CDC, there were 8,916 new cases of TB reported in the United States in 2019

Nearly two billion people (about 25% of the world’s population) are infected with Mycobacterium tuberculosis worldwide

In 2019, WHO reported that nearly 205,030 people developed MDR-TB (10% increase from 2018)

DIAGNOSIS

Mantoux tuberculin skin test

Acid-fast bacilli (AFB) sputum cultures

The QuantiFERON-TB Gold (QFT-G) test

The rapid Xpert MTB/RI assay

. In 2017, however, WHO recommended the use of Xpert Ultra as a replacement for Xpert in all settings when available. In general, Xpert Ultra appears to be more sensitive than the Xpert MTB/RIF assay for detection of TB in (1) smear-negative but culture-positive specimens, (2) pediatric specimens, (3) extrapulmonary specimens (notably cerebrospinal fluid), and (4) specimens from HIV-infected individuals

MANTOUX TUBERCULIN SKIN TEST

Injection of purified protein derivative (PPD)

An induration less than 5  mm is a negative result

An induration of 5–9 mm is considered suspicious, and retesting is required

An induration of 10 mm or greater is considered a positive result

A positive reaction is fairly sound evidence of recent or past infection or of active disease

ACID-FAST STAINING

TB organism has an unusual, waxy coating on the cell surface

The cells are impervious to staining

An acid-fast bacteria (AFB) test (also called a sputum smear) is performed instead

OVERVIEW OF THE CARDIOPULMONARY CLINICAL MANIFESTATIONS ASSOCIATED WITH TUBERCULOSIS

Alveolar consolidation

Increased alveolar-capillary membrane thickness

THE PHYSICAL EXAMINATION (1 OF 2)

Vital signs

Chest pain/decreased chest expansion

Cyanosis

Digital clubbing

Peripheral edema and venous distention

Distended neck veins

Pitting edema

Enlarged and tender liver

Cough, sputum production, and hemoptysis

Chest assessment findings

Increased tactile and vocal fremitus

Dull percussion note

Bronchial breath sounds

Crackles and wheezing

Pleural friction rub

if process extends to pleural surface

Whispered pectoriloquy

PULMONARY FUNCTION TEST FINDINGS
MODERATE AND EXTENSIVE CASES
(RESTRICTIVE LUNG PATHOPHYSIOLOGY) (1 OF 2)

Forced Expiratory Volume and Flowrate Findings

FVC FEVT FEV1/FVC ratio FEF25%-75

↓ N or ↓ N or ↑ N or ↓

FEF50% FEF200-1200 PEFR MVV

N or ↓ N or ↓ N or ↓ N or ↓

PULMONARY FUNCTION TEST FINDINGS
MODERATE AND EXTENSIVE CASES
(RESTRICTIVE LUNG PATHOPHYSIOLOGY) (2 OF 2)

Lung Volume & Capacity Findings

VT IRV ERV RV VC

N or ↓ ↓ ↓ ↓ ↓

IC FRC TLC RV/TLC ratio

↓ ↓ ↓ N

16

ARTERIAL BLOOD GASES
EXTENSIVE TUBERCULOSIS WITH PULMONARY FIBROSIS

Chronic Ventilatory Failure with Hypoxemia
(Compensated Respiratory Acidosis)

pH PaCO2 HCO3 − PaO2 SaO2/SpO2

N ↑ ↑ ↓ ↓

(significantly)

ABNORMAL LABORATORY TESTS AND PROCEDURES

Positive tuberculosis skin test (PPD)

Positive sputum acid-fast bacillus (AFB) stain test

Positive sputum culture

Positve quantiFERON-TB Gold Test

RADIOLOGIC FINDINGS

Chest radiograph

Increased opacity

Ghon nodule

Ghon complex

Cavity formation

Cavity lesion containing an air-fluid level (see Fig. 17.2)

Pleural effusion

Calcification and fibrosis

Retraction of lung segments or lobe

Right ventricular enlargement

Cavity Reactivation TB

MILIARY TB

GENERAL MANAGEMENT OF tb

Pharmacologic agents

Consists of 2 to 4 drugs for 6 to 9 months

6-month treatment protocol:

For the first 2 months (called the induction phase), the patient takes a daily dose of isoniazid (INH), rifampin (RIF), pyrazinamide (PZA), and either ethambutol (EMB, E) or streptomycin (SM)

For the next 4 months, the patient takes isoniazid and rifampin daily or twice weekly

9-month treatment protocol:

For the first 1 to 2 months, the patient takes a daily dose of isoniazid and rifampin

Followed by twice-weekly isoniazid and rifampin until the full 9-month period is completed

Isoniazid (INH) and rifampin (Rifadin) are first-line agents prescribed for the entire 9 months.

Isoniazid is considered to be the most effective first-line antituberculosis agent

Rifampin is bactericidal and is most commonly used with isoniazid

When the TB is resistant to one or more of these agents, at least three or more antibiotics must be added to the treatment regimen and the duration should be extended

A major problem with TB therapy is noncompliance on the part of the patient to take the TB medication as prescribed

In response to the problem of noncompliance, it is recommended that all such patients with TB be treated by directly observed therapy (DOT)

The ingestion of medication is directly observed by a responsible individual

RESPIRATORY CARE TREATMENT PROTOCOLS

Oxygen therapy protocol

Airway clearance therapy protocol

Mechanical ventilation protocol

Infectious control measures protocols

Note