Our aim in this study is to investigate the efficiency of the breathing with different breathing patterns. Ten volunteers and twenty patients having respiratory problems will be coached on their breathing through specific masks which will provide four different breathing patterns. These patterns will be 1) Breathing in through the nose only and out through the mouth only 2) Breathing in through the mouth only and out through the nose only 3) Breathing in and out through the nose only 4) Breathing in and out through the mouth only The data obtained from volunteers and patients will be compared within and between the groups.

Inclusion Criteria:

• For healthy subjects:

  1. Ten healthy adult (> 18 years of age) volunteers will be recruited from the MGH main campus through intra-hospital e-mail broadcasting. Subjects with the following issues will be excluded from the study.

• For patients with respiratory insufficiency:

  1. Twenty adult (> 18 years of age) patients will be recruited. These patients will be either patients in acute respiratory failure resulting from COPD exacerbation breathing spontaneously only receiving nasal oxygen admitted to the medical floors of the MGH; or patients with diagnosed stable COPD on home oxygen therapy seen by pulmonary physicians in the outpatient clinics or coming to the MGH as study subjects.

Exclusion Criteria:

• For healthy volunteers:

  1. Subjects with facial deformity, heavy beard or moustache which prevents good seal between the mask and the face;
  2. Subjects who have claustrophobia and cannot wear the mask.

• For patients with respiratory insufficiency:

  1. Patients with facial deformity, heavy beard or moustache which prevents a good seal between the mask and the face;
  2. Patients who have claustrophobia and cannot wear the mask.
  3. Patients who are hemodynamically unstable.
  4. Patients requiring continuous noninvasive positive pressure ventilation or endotracheal intubation.