Pulmonary Pathophysiology Flashcards
What is the most common post-op complication and what is the rate of incidence?
Post-Op Pulm Dysfunction
Occurs between 6-60% of surgical population
What are the 4 categories of pulmonary pathophysiology?
- Post-Op Pulm Dysfunction
- Obstructive Lung Disease
- Restrictive Lung Disease
- Combination Obstructive/Restrictive Disease
What are some examples of Post-Op Pulm Dysfunction complications?
- Atelectasis
- Pneumonia
- PE
- Respiratory Failure
What are the risk factors for Post-Op Pulm Dysfunction?
*Operative Site (Thoracic and Upper Abd surgery causes splinting
because the Pt doesn’t want to take a tidal volume breath
secondary to pain)
*Surgical Duration (The longer the surgery, the greater the risk; dry
air will dry out Pulm system which causes stress to system)
*Pre-op Pulm Dysfunction
- Hx of dyspnea: pre-existing Dz, on home O2, SOB at rest
or on exertion
- Smoking: can’t clear secretions, damaged lungs can’t
protect themselves
- Advanced Age: widens the A/a gradient, destruction of
alveoli and capillaries, larger V/Q mismatch
- Obesity: decreases FRC
Describe what causes diaphragmatic dysfunction and what happens when this post-op pulm dysfunction occurs.
Diaphragmatic dysfunction occurs after upper abd and thoracic surgeries due to pain from the incision, inflammation and subsequent splinting.
The diaphragm doesn’t work as well because it bows up and, therefor, won’t allow for full lung expansion as a protective mechanism.
In upper abd and thoracic surgery, what is the decreased FRC post-op? When is this decrease at its maximum? How long does this decrease last?
FRC decreases 60-70%
It is maximal post-op day 1 (POD #1)
Decreases last 7-10 days
Pt’s s/p upper abd and thoracic surgeries have an increased work of breathing. What does this mean?
Pt’s use an increased amount of energy to breathe. This increases stress on the Pt and leads to an increased oxygen requirement.
What leads to decreased clearance of mucus in upper abd and thoracic surgeries? Why is this considered post-op pulm dynfunction?
The ETT itself, the dry air used to ventilate the Pt
Decreased clearance of mucus leads to pooling of mucus, which can result in infection, pneumonia and V/Q mismatch
Why does a Pt have decreased coughing after upper abd or thoracic surgery?
pain protection
What post-op pulm dysfunctions would you expect in upper abd and thoracic surgeries?
- Diaphragmatic dysfunction
- Decreased FRC
- Increased work of breathing
- Decreased clearance of mucus
- Decreased coughing
- Pulm shunting
Describe pulmonary shunting
The Pt has unventilated alveoli, meaning that blood passes by without ‘picking up’ oxygen. This leads to hypoxic vasoconstriction, which acts as a protective mechanism (though can’t completely protect the pulm system) and eventually leads to increased right ventricle pressure, increased pulmonary vascular resistance and, ultimately, (short term or longterm) pulmonary HTN.
What are the Co-existing established risks for post-op pulmonary complications?
- Smoking
- Obstructive lung disease (COPD, poorly controlled asthma)
- Malnutrition
- Chronic respiratory tract infections
What are the co-existing potential risks for post-op pulmonary complications?
- Age
- Obesity
- Stable or Mild Asthma
What are the surgery associated established risks for post-op pulmonary complications?
*Surgery Type (Thoracic/Upper Abd > Lower Abd > Peripheral)
*Type of incision (Thoracotomy ie between ribs > Sternotomy ie
down sternum)
*Type of anesthesia (General > Neuraxial/Regional, even in
peripheral surgeries)
*Duration of surgery (The longer the surgery, the great the risk)
Note: if a lung is collapsed during the proceedure (1 lung ventilation), there is an even greater risk to the pulmonary system)
What are the surgery associated potential risk levels for post-op pulmonary complications during a thoracotomy?
The risk level increases according to how the surgical site is accessed
Posteriolateral thoracotomy > muscles-sparing thoracotomy > thoroscopic
Describe the difference between obstructive lung disease and restrictive lung disease
In OBSTRUCTIVE lung disease, the lungs are hyper-inflated (overextended) which leads to a greater residual volume/FRC. It is harder for the Pt to exhale and takes greater work and time to move air out of the lungs.
In RESTRICTIVE lung disease, lung volumes are decreased due to a limitation in how well the lungs can expand. It takes more work and energy to inhale.
What are examples of obstructive lung disease?
- Asthma (from mild to severe, though can out grow)
* COPD (aka emphysema, progressive, usually related to environmental exposure)
True or False: Too light of an anesthetic during intubation can lead to a reaction from hypersensitive airways.
True.
Smooth bronchial muscles will spasm/contract/constrict leading to narrowing of the airways, which is the 1st phase of the asthmatic response.
True or False: An asthmatic has an abnormal airway, which leads to hypersensitivity.
FALSE.
An asthmatic does have a hypersensitive airway, but their airway is normal until the hypersensitivity is triggered by a stimulus. The stimulus can be internal (mismatch between sympathetic/parasympathetic state), external or environmental
Describe the physiological changes that occur during acute asthma exacerbation
Bronchial Muscle Hyperactivity -> Airflow Limitations -> Recruitment of Inflammatory Cells and Mediators -> Continued and Worsening Bronchospams -> Alveolar Fluid Extravisation
Note: this is another way he described it -
A Pt’s bronchioles respond to a stimulus -> bronchial smooth mucles spasm leading to contraction/constriction and narrowing of the airways -> inflammatory cells act as inflammatory mediators -> hyper secretory response occurs -> mucus fills Pt’s airway -> more bronchospasm occurs in already narrowed airways
What are the primary and secondary phases of an asthma attack, respectively?
primary: bronchoconstriction
secondary: inflammation
What are potential treatments for asthma?
- Bronchodilators
- Steriods
- Anticholinergics
- Methylxanthines
