Background: The increase in peripheral chemoreflex sensitivity in patients with obstructive sleepapnea (OSA) is associated with activation of autonomic nervous system and hemodynamicresponses. Nasal CPAP (nCPAP) is an effective treatment for OSA, but little is known on its effecton chemoreflex sensitivity.Objectives: To assess the effect of nCPAP treatment or placebo (sham nCPAP) on ventilatorycontrol in patients with OSA.Setting: Sleep laboratory of Azienda Ospedaliera Garibaldi.Patients: Twenty-five patients with moderate-to-severe OSA.Design and measurements: Patients were randomly assigned to either therapeutic nCPAP (use ofoptimal pressure, n _ 15) or sham nCPAP (suboptimal pressure of 1 to 2 cm H2O, n _ 10) in adouble-blind fashion and treated for 1 month. A rebreathing test to assess ventilatory response tonormocapnic hypoxia and normoxic hypercapnia was performed at basal condition and after 1month of treatment.Results: The use of therapeutic nCPAP or sham nCPAP did not affect daytime percentage ofarterial oxygen saturation (SaO2%) or end-tidal PCO2. The normocapnic hypoxic ventilatoryresponse was reduced after 1 month of treatment with nCPAP (the slope was 1.08 _ 0.02L/min/SaO2% at basal condition and 0.53 _ 0.07 L/min/SaO2% after 1 month of treatment,p _ 0.008) [mean _ SD], but not in patients treated with sham nCPAP (slope, 0.83 _ 0.09L/min/SaO2% and 0.85 _ 0.19 L/min/SaO2% at basal condition and after 1 month, respectively).The normoxic hypercapnic ventilatory response remained unchanged after 1 month in bothgroups. No changes in ventilatory response to either hypoxia or hypercapnia were observed aftera single night of nCPAP treatment.Conclusion: The ventilatory response to hypoxia is reduced during regular treatment, but notafter short-term treatment, with nCPAP. Readjusted peripheral oxygen chemosensitivity duringnCPAP treatment may be a side effect of both reduced sympathetic activity and increasedbaroreflex activity, or a possible continuous positive airway pressure-related mechanism leadingto a reduced activation of autonomic nervous system per se. (CHEST 2006; 130:774–779)
Effect of treatment with nasal continuous positive airway pressure on ventilatory response to hypoxia and hypercapnia in patients with sleep apnea syndrome
SPICUZZA L;POLOSA, Riccardo;DI MARIA, Giuseppe Ugo
2006-01-01
Abstract
Background: The increase in peripheral chemoreflex sensitivity in patients with obstructive sleepapnea (OSA) is associated with activation of autonomic nervous system and hemodynamicresponses. Nasal CPAP (nCPAP) is an effective treatment for OSA, but little is known on its effecton chemoreflex sensitivity.Objectives: To assess the effect of nCPAP treatment or placebo (sham nCPAP) on ventilatorycontrol in patients with OSA.Setting: Sleep laboratory of Azienda Ospedaliera Garibaldi.Patients: Twenty-five patients with moderate-to-severe OSA.Design and measurements: Patients were randomly assigned to either therapeutic nCPAP (use ofoptimal pressure, n _ 15) or sham nCPAP (suboptimal pressure of 1 to 2 cm H2O, n _ 10) in adouble-blind fashion and treated for 1 month. A rebreathing test to assess ventilatory response tonormocapnic hypoxia and normoxic hypercapnia was performed at basal condition and after 1month of treatment.Results: The use of therapeutic nCPAP or sham nCPAP did not affect daytime percentage ofarterial oxygen saturation (SaO2%) or end-tidal PCO2. The normocapnic hypoxic ventilatoryresponse was reduced after 1 month of treatment with nCPAP (the slope was 1.08 _ 0.02L/min/SaO2% at basal condition and 0.53 _ 0.07 L/min/SaO2% after 1 month of treatment,p _ 0.008) [mean _ SD], but not in patients treated with sham nCPAP (slope, 0.83 _ 0.09L/min/SaO2% and 0.85 _ 0.19 L/min/SaO2% at basal condition and after 1 month, respectively).The normoxic hypercapnic ventilatory response remained unchanged after 1 month in bothgroups. No changes in ventilatory response to either hypoxia or hypercapnia were observed aftera single night of nCPAP treatment.Conclusion: The ventilatory response to hypoxia is reduced during regular treatment, but notafter short-term treatment, with nCPAP. Readjusted peripheral oxygen chemosensitivity duringnCPAP treatment may be a side effect of both reduced sympathetic activity and increasedbaroreflex activity, or a possible continuous positive airway pressure-related mechanism leadingto a reduced activation of autonomic nervous system per se. (CHEST 2006; 130:774–779)I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
