BiPAP and Swallowing

 

 

BiPAP, or bi-level positive airway pressure, is a type of noninvasive ventilation that helps keep the upper airways of the lungs open by providing a flow of air delivered through a face mask. The air is pressurized by a machine, which delivers it to the face mask through long, plastic hosing.  BiPAP delivers positive pressure while a person breathes in and lowers the air pressure when a person breathes out. Thus, the BiPAP has preset pressures: EPAP (exhalation pressure) and IPAP (inhalation pressure). The machine may also have a timing feature for breaths per minute (BPM).The indications of BiPAP include exacerbations of COPD associated with hypercapnia, cardiogenic pulmonary edema associated with hypercapnia and/or unresponsive to CPAP alone, respiratory distress and pulmonary infiltrates in immunosuppressed patients.  Other indications include acute on chronic hypercapnic respiratory failure due to chest wall deformity or neuromuscular disease, and decompensated obstructive sleep apnea with hypercapnia.

 

If the patient is only using BiPAP nocturnally such as for obstructive sleep apnea, this would not interfere with the patient’s swallow or eating.  However, if the patient requires continuous BIPAP, it would seem that these patients are at high risk of aspiration.  A patient on continuous BiPAP has a reduced respiratory status and usually hypercapnia.  Hypercapnia is when there is a high concentration of CO2 in the blood.  Symptoms of hypercapnia include tachypnea (rapid breathing) and dyspnea (shortness of breath).  One study showed that patients with hypercapnia may be at high risk of aspiration with 7/11 subjects showing signs of aspiration and the incidence was higher with higher PaCO2 (1998, Takashi, N. Risahasegawa, T Shiroisono).  Patients may have hypercapnia when they are off BiPAP for short periods.  That is why is is a good idea to check the ABG that was done when the pt is off BiPAP for the PaCO2. 

 

In a study with patients who have COPD, the researchers looked at the pattern of inhalation and exhalation.  COPD patients swallowed solid food during inhalation more frequently than normal subjects (P 0.002) and had a significantly higher rate of inhaling after swallowing semi-solid material (P<0.001).  The disrupted breathing-swallowing coordination could increase the risk of aspiration in patients with advanced COPD and may contribute to exacerbation (2009, Gross, RD et.al). If COPD patients have an exacerbation and require BiPAP, respiratory status is more comprimised, which would make them an even high risk for aspiration.

 

 

Another study found that bolus aggregation in the valleculae usually occurred during an extended plateau in nasal air pressure following active expiration. This suggests that aspiration during eating is prevented by inhibiting respiration during bolus formation in the oropharynx. (2003, Palmer JB, Hiiemai KM).  If a patient is on continuous BiPAP, we would have to remove the BIPAP for a few seconds for the patient to take a bite to eat and then place the BIPAP back on after food is given to prevent respiratory distress.  If the BIPAP is placed while there is still food in the oral cavity/oropharynx, this food can be forced into the airway by the positive pressure of the BIPAP machine.

 

 

It is safer for the patient to tolerate coming off the BIPAP machine for at least 30-60 minutes before eating.  The patient should be able to tolerate nasal cannula or mask.  These patients appear to still be at a high aspiration risk.  In addition to the usual bedside swallow evaluation, check that the patient’s PaCO2 is normal or close to normal and that the patient’s respiratory rate is lower than 35bpm. If, based on MD assessment, the patient is at end of life, consider the patient’s comfort. 

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References:

Takashi, N., Risahasegawa, T, Shiroisono.  Hypercapnia Enhances the Development of Coughing during Continuous Infusion of Water into the Pharynx . Am J Respir Crit Care Med. March 1, 1998 vol. 157 no. 3 815-821.