Hypoventilation and hyperventilation

Hypoventilation and hyperventilation

1. Hypoventilation
and
Hyperventilation
A student seminar - Bshr Nammouz - 4’th
year medical school - SSST

2. Hypoventilation
Syndromes

3. insufficient ventilation leading to
hypercapnia

4. We will discuss shortly:
●Central alveolar hypoventilation
●Obesity-hypoventilation syndrome (OHS)
●Chest wall deformities
●Neuromuscular disorders
●Chronic obstructive pulmonary disease (COPD)

5. Alveolar ventilation (VA) is under the control
of the central respiratory centers
which are located in the ventral aspects of the pons and medulla.

7. Central alveolar hypoventilation:
such as cerebrovascular accidents, trauma, and neoplasms

8. Obesity-hypoventilation syndrome:
defined as a combination of
1.obesity a body mass index greater than or equal to 30kg/m
2

2.awake chronic hypercapnia (PaCO
2
>45 mm Hg)
3.sleep-disordered breathing

9. Obesity Hypoventilation Syndrome
https://www.youtube.com/watch?v=7kIFRjqaORQ

10. Neuromuscular disorders:
include myasthenia gravis, amyotrophic lateral sclerosis, Guillain-Barré syndrome, and
muscular dystrophy.

11. Chronic obstructive pulmonary disease
●not uncommon
●secondary to multiple mechanisms
●a decreased chemical responsiveness to hypoxia and hypercapnia

12. History
Clinical manifestations are nonspecific, and in most cases, they are secondary to the
underlying clinical diagnosis.

13. Treatment:
1.Correcting the underlying disorder
2.Bronchodilators beta agonists and anticholinergic agents
3.Theophylline may improve diaphragm muscle contractility and stimulate the respiratory
center

14. Assisting Ventilation
Endotracheal intubation with mechanical ventilation and noninvasive ventilatory techniques

15. Weight loss
Diet or surgery

16. Hyperventilation
Syndrome

17. Can be acute or chronic

18. Hyperventilation Syndrome
https://www.youtube.com/watch?v=p97HeXx0vN0

19. Acute hyperventilation
1.Patients often present dramatically, with agitation, hyperpnea and tachypnea, chest
pain, dyspnea, wheezing, dizziness, palpitations, tetanic cramps (eg, carpopedal
spasm), paresthesias, generalized weakness, and syncope.
2.A sense of suffocation. An emotionally stressful precipitating event can often be
identified.

20. Acute Hyperventilation Syndrome
https://www.youtube.com/watch?v=Zt6W_cNQS8M

21. minute ventilation exceeds metabolic demands, resulting in hemodynamic and chemical
changes that produce characteristic dysphoric symptoms.

22. Why
●Certain stressors provoke an exaggerated respiratory response. Several such stressors
have been identified, including emotional distress, sodium lactate, caffeine,
isoproterenol, cholecystokinin, and carbon dioxide.
●Predisposition to HVS may also be rooted in childhood.

23. ●Normal tidal volume is 7 mL/kg of body mass.
●The elastic recoil of the chest wall resists hyperinflation of the lungs beyond that level,
and inspiratory volumes beyond this level are perceived as effort or dyspnea.
●Patients with HVS tend to breathe by using the upper thorax rather than the
diaphragm, and this results in chronic overinflation of the lungs.
●When stress induces a need to take a deep breath, the deep breathing is perceived as
dyspnea. The sensation of dyspnea creates anxiety, which encourages more deep
breathing, and a vicious circle is created.

24. Relation to panic disorder
●Overlapping with panic disorder
●Also, elevated levels of carbon dioxide have been
demonstrated to induce panic symptoms in a majority of
patients with panic disorder

25. Diagnosis
●A low pulse oximetry reading in a patient who is hyperventilating should never be
attributed to HVS. These patients should always be evaluated for other causes of
hyperventilation.
●Arterial blood gas (ABG), In chronic HVS, respiratory alkalosis in a majority of cases.

26. ECG
Electrocardiographic changes are common and may include the following:
●ST depression or elevation
●Prolonged QT interval
●T-wave inversion
●Sinus tachycardia

27. Should be differentiated from PE and AMI.
DDs:

28. Workup
Rebreathing into a paper bag is not recommended. Deaths have occurred in patients with
acute myocardial infarction (MI), pneumothorax, and pulmonary embolism (PE) who were
initially misdiagnosed with HVS and treated with paper bag rebreathing.

29. ●Benzodiazepines.
●Selective serotonin reuptake inhibitors (SSRIs).
●Stress reduction therapy.
●Beta blockers.
●Reathing retraining.

●If the diagnosis of HVS has been established, the patient should be referred to an
appropriate therapist to implement these techniques over the long term.

30. Thanks for your
attention
Reference: Medscape