This textbook says:

Consequently, young children are prone to suffer from pneumonia after abdominal operations, because they resist breathing (being abdominal) due to pain. As a result the secretions in the lungs tend to accumulate, which may become infected and cause pneumonia.

Iam unable to find which secretions are they and how breathing removes them from lungs?

I thought it could be pleural effusion but unable to figure out the mechanism involved and how it gets infected if it remains there for long.

  • 1
    $\begingroup$ As an aside, it's not just young children that are susceptible to pneumonia after abdominal surgery, and the subsequent infections are almost always nosocomial. I had a very personal experience with that many years ago, in my late teens. $\endgroup$
    – MattDMo
    Commented Jan 14, 2017 at 18:59
  • $\begingroup$ Mucus is always being secreted and removed by ciliated cells. $\endgroup$ Commented Jan 14, 2017 at 19:21
  • $\begingroup$ @GrahamChiu So do you think resisting breathing will lead to clog up of mucus? $\endgroup$
    – JM97
    Commented Jan 15, 2017 at 0:39
  • 3
    $\begingroup$ Inadequate chest wall and diaphragm movement will lead to atelectasis, and an inability to clear secretions. $\endgroup$ Commented Jan 15, 2017 at 0:50

2 Answers 2


Abdominal surgery results in a painful wound that affects the abdominal muscles, which are important for coughing. The Lungs and respiratory tracts constantly secrete mucus that flows upwards to the Trachea then down the Oesophagus. The trachea is lined with a moist mucous-membrane layer composed of cells containing small hairlike projections called Cilia. The Cilia project into the channel (lumen) of the trachea to trap particles. The Cilia constantly move in a manner that pushes the mucus up to help clear the respiratory tract of pollutants, debris and bacteria. Here is a link to show the Cilia Movement:


Abdominal Surgery reduces the efficiency of the cough reflex due to abdominal wound pain, while the Anaesthetic results in an increase in mucus due to the upper respiratory tract trauma, with some anaesthetic drugs also increasing these secretions and suppressing Cilia movement. All that eventually results in secretions being produced at a higher rate than being evacuated leading them to accumulate and resulting in an increased risk of lung infection.

  • $\begingroup$ This is largely correct, though it could do with some references. $\endgroup$
    – De Novo
    Commented Dec 19, 2018 at 23:06

Pneumonia after abdominal surgery can develop due to:

  • Decreased breathing movements when lying in the bed
  • Anesthetics/sedation use that decrease the sensation of irritation in the lungs and hence coughing out mucus
  • Pain preventing coughing
  • Eventual mechanical ventilation, especially when the organism is not immune to hospital-acquired (nosocomial) organisms, especially staphylococci
  • Spread of bacteria from the gut to the lungs via the blood)
  • Eventual underlying lung disease

Source: Post-operative pneumonia (TeachMeSurgery)


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