Respiratory Care: Assessment and Management

Debbie Duncan

• Publisher: M&K Update
• Year: 2017
• ISBN:
  9781910451526
• Topic: Médecine
• Subtopic: Médecine pulmonaire et thoracique

More than 30% of patients who visit a doctor each year have respiratory complaints. These can range from minor infections (such as the common cold) to chronic obstructive conditions (such as asthma).This helpful book looks at the respiratory problems that nursing and healthcare professionals are most likely to encounter in clinical practice. Beginning with an overview of the respiratory system, the author then discusses history taking, and the physical assessment and secondary tests needed to assess a patient with an undiagnosed respiratory condition. This is followed by chapters on the aetiology, assessment and management of specific acute and chronic conditions, as well as a chapter on the pharmacology of respiratory disease. Finally, the author looks at intermediate, home-based and end of life care.Featuring boxes, tables, diagrams, reader activities, a list of abbreviations and a full glossary, this book offers a holistic and practical approach to caring for a patient with a respiratory disease.

Chapter 1

A quick look at anatomy and physiology

To assess and manage a patient with a respiratory problem, you need to have a full understanding of the anatomy and physiology of that system. This chapter will discuss the role of the respiratory system, concentrating on its major anatomical structures. It will then look at the science of respiration. There is also a reader activity at the end of the chapter.

The respiratory system

The respiratory system carries out the activity of breathing or inhalation. This is the movement of air into the lungs to supply the body with oxygen. The respiratory system is also responsible for the movement of air out of the lungs, to expel carbon dioxide, known as exhalation.

The major anatomical structures in the respiratory system are: the nose, pharynx, larynx, trachea, the two bronchi and the lungs. The lungs include the bronchioles and the alveoli. The lungs themselves are surrounded by the pleurae. There is a thin layer of tissue called the visceral pleura, which covers the lungs. This layer also covers the chest wall and surrounds the heart and is called the parietal pleura. There is a thin layer of fluid between the visceral and parietal pleurae, which allows movement between them. The space between the visceral and parietal layers is called the pleural space.

The respiratory system is divided into two parts. One is the conducting part, which passes air into the lungs. This includes the nasal passages and the pharynx, larynx, trachea, bronchi and larger bronchioles. The second part is called the respiratory part, and this is where gas exchange occurs in the smaller bronchioles and alveoli.

The nose is the start of the respiratory system. The nasal cavity is hollow so the air passes through it, while being heated and moistened. The cavity is lined with hair and mucus, which acts a filter, trapping foreign particles. The other opening is the mouth or oval cavity. The nose is generally used for the activity of breathing, as the mouth lacks a filter system. This explains why people who breathe through their mouths have a higher incidence of oral infections (Abreu et al. 2008, Gulati, Grewal & Kaur 1998). The air is then passed to the pharynx.

The pharynx is a fibromuscular tube situated behind the nasal cavity, the oral cavity and the larynx. It is usually called the throat and extends from the base of the skull level to C6 or the cricoid cartilage. Its function is to deliver food products from the mouth to the oesophagus. It also warms, moistens and filters the air we inhale.

The nasopharynx is found behind the nasal cavity and the soft palate. When you swallow food, it passes through the oropharynx and the laryngopharynx. The soft palate rises, allowing the pharyngeal wall to pull forward and form a seal over the nasopharynx. The oropharynx lies between the soft palate and the base of the tongue. The narrower laryngopharynx extends from the hyoid bone and the start of the oesophagus.

The two laryngeal cartilages that can be felt during a neck examination are the laryngeal cartilage (or ‘Adam’s apple’) and the slightly lower cricoid cartilage. The distance between the laryngeal cartilage and the sternal notch is used to assess lung hyperinflation (Bickley 2003).

The warmed air then leaves the pharynx and enters the larynx (voice box). This is an area of ligaments and muscle. The trachea is attached to the cricoid cartilage of the larynx. It is roughly 2.5cm in diameter and 10–12cm long. The walls are surrounded by cartilage to protect the airway from collapsing. In the disorder tracheomalacia, there can be a weakness in the longitudinal fibres of the trachea or impaired cartilage integrity which can cause trapping and collection of secretions that can lead to infection (Carden et al. 2005). Interestingly the shape of the adult trachea varies even without disease – as some remain circular and others a more ovoid shape (Tewfik & Gest 2015).

The trachea divides into the right and left main bronchi at the keel-like partition called the carina. It is situated to the left of the median line. However, the right bronchus appears to be more central than the left, making it look like a direct continuation of the trachea (Tewfik & Gest 2015). It then branches into the lobar, segmental and sub-segmental bronchi. It divides a further 25 times into the pulmonary alveoli at the terminal ends of the respiratory tree where the gas transfer occurs.

The first seven divisions are called the larger airways. These contain:

Ciliated epithelium, which contains goblet cells. These glandular cells secrete a gelforming mucin found in mucus, called airway surface liquid (ASL). ASL has a mucus component that traps the inhaled particles and a soluble layer, which keeps mucus at an optimum distance from the underlying epithelia, preventing easy clearance (Tarran 2004).

Mucus-secreting cells in the submucosal.

Endocrine cells.

Cartilage and smooth muscle in the branch walls.

The remaining 16–18 branches are called the small airways. They have cells that produce surfactant, which reduces the surface tension of fluid in the lungs. They contain fewer goblet cells and there is no cartilage present.

Box 1.1: Cystic fibrosis

In the genetic disorder cystic fibrosis, the goblet cells in the mucosal produce thick, sticky mucus. It cannot be transported out of the respiratory system by the cilia that line the tract. The smaller passages become blocked with this dense mucus, leading to significant infection and poor gas exchange.

Air flow

The movement of air in the respiratory system depends on the difference in air pressure between the oral cavity and the pulmonary alveoli. When you breathe in, the intrathoracic pressure drops below the atmospheric pressure. The air is therefore forced into the alveolar tree. When you breathe out, the muscles in the lung and chest wall recoil like elastic. This causes the intrathoracic pressure to rise above atmospheric pressure. In Alpha-1 antitrypsin (A1AT) deficiency there is a lack of the elasticity needed to allow the airways to recoil.

The rate at which air can move along the airways therefore depends on any resistance in the airway. Any problem with the lumen of the airway can potentially increase this resistance.

Such problems can include:

Contents blocking the lumen of the airway

Internal or external pressure

Lack of muscle tone

The thickness of the e...