• N Weksler and L Ovadia.
• Department of Anesthesiology, Hillel Yaffe Medical Center, Hadera, Israel.
• J Clin Anesth. 1991 Nov 1; 3 (6): 442-6.

Study ObjectiveTo examine the efficacy of a nasal continuous positive airway pressure (CPAP) system for respiratory support in patients who have respiratory insufficiency but are able to maintain spontaneous breathing without hypercapnia, respiratory acidosis, or deteriorated mental status.DesignProspective study.SettingMedical and surgical patients admitted to the intensive care unit (ICU) at the Hillel Yaffe Medical Center.PatientsNineteen patients with acute respiratory insufficiency and intact mental status who were able to maintain spontaneous breathing without hypercapnia or respiratory acidosis. Additional entry criteria were as follows: arterial oxygen tension (PaO2) less than 65 mmHg on inspired oxygen tension (FIO2) greater than or equal to 0.45, PaO2/FIO2 less than 150, respiratory rate greater than 35 breaths/minute, and inability to tolerate mask CPAP.InterventionsNasal CPAP (10 cmH2O) was applied to patients through two nasopharyngeal airways with an internal diameter (ID) of 8 mm each, inserted in both nostrils. During CPAP application, the patients were requested to breathe through their nose with their mouth closed. Even if they breathed through their open mouth, however, CPAP was maintained despite an observed pressure decrease of 4 cmH2O.Measurements And Main ResultsAll patients showed a constant improvement in arterial blood gases, PaO2/FIO2, and respiratory signs during nasal CPAP of 10 cmH2O. PaO2 increased from 52 +/- 5.3 mmHg to 131 +/- 20 mmHg with CPAP administration (p less than 0.05), while arterial carbon dioxide tension (PaCO2) increased from 32 +/- 2 mmHg to 36 +/- 2 mmHg (p less than 0.05) and respiratory rate decreased from 39 +/- 2.3 breaths/minute to 31 +/- 1.6 breaths/minute (p less than 0.05).ConclusionsNasal CPAP (10 cmH2O) is a reliable alternative to support arterial oxygenation in patients with respiratory failure who are alert and vigorous enough to avoid hypercapnia and respiratory acidosis while breathing spontaneously. In addition, since the patients are able to speak and thus are capable of expressing their feelings, the anxiety observed during respiratory support can be reduced.

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