Breathing patterns during vaso-occlusive crisis of sickle cell disease.

STUDY OBJECTIVES To determine the effect of sickle cell pain and its treatment on patients' breathing patterns, and to compare the effect of thoracic cage pain to pain at other sites. DESIGN Prospective, observational study. SETTING Sickle Cell Center Day Hospital. PATIENTS Twenty-five patients with sickle cell disease admitted to the Sickle Cell Center Day Hospital for treatment of vaso-occlusive crisis (VOC) [10 patients with chest (thoracic cage) pain]. INTERVENTIONS Breathing patterns were measured by respiratory inductive plethysmography. Tidal breathing data, including respiratory rate, tidal volume (VT), minute ventilation, and the rib cage contribution to VT, were collected at baseline and then following treatment with opioid analgesia. MEASUREMENTS AND RESULTS The patients with chest pain had smaller V(Ts) at baseline than those with pain at other sites (355 +/- 37 mL vs 508 +/- 141 mL, p = 0.003), and higher respiratory rates (23.2 +/- 8.2 breaths/min vs 17.6 breaths/min, p = 0.03). These differences became insignificant following opioid treatment. Six patients had respiratory alternans (four patients in the chest pain group, and two patients with pain at other sites). All cases of respiratory alternans resolved following opioid administration. CONCLUSIONS Patients with VOC and chest pain have more shallow, rapid breathing than patients with pain elsewhere. Analgesia reduces these differences. As pain-associated shallow breathing and maldistribution of ventilation may contribute to the pathogenesis of acute chest syndrome, these results support the need for adequate pain relief and monitoring of ventilatory patterns during the treatment of VOC.