And then if a respiratory infection should occur it is more likely that pneumonia can be avoided because ventilation stays stronger and the assisted ventilation provides a bigger breath in, so that a better cough is possible to eliminate excess secretions. Pneumonia creates severe problems, regardless of whether you are breathing independently or on a ventilator. The heart compensates by increasing heart rate and cardiac output in order to deliver more oxygen to the tissues. The circulation of blood is somewhat like a train. When it is loaded with less oxygen the train circulates more often around the circuit in order to deliver enough oxygen to each point on the way, by making extra trips with a smaller load of oxygen each time.
Most people can provide the extra heart work to increase circulation without a problem.
Older people or those with heart disease may not do as well. The larger the percent of the lung involved with pneumonia the greater the problem of course. Unfortunately, giving a person more oxygen is not very effective when the decreased SaO2 is due to pneumonia. While some people have difficulty with Influenza immunizations, most people do not and definitely will benefit from them if there is an influenza epidemic. Key Points Oxygen saturation levels will remain low, even when using a ventilator, if pneumonia is present.