Chẩn đoán phân biệt của PFTS Bảng 18-1 cho thấy chẩn đoán phân biệt của các mô hình PFT khác nhau. Khi giải thích PFTs, hãy nhớ rằng một số bệnh nhân có thể có kết hợp bệnh hạn chế và tắc nghẽn như khí phế thũng và asbestosis. | 18 Respiratory Care 361 Vital Capacity VC Maximum volume of air that can be exhaled from the lungs after a maximal inspiration Residual Volume RV The volume of air remaining in the lungs at the end of a maximal exhalation DIFFERENTIAL DIAGNOSIS OF PFTS Table 18-1 shows the differential diagnosis of various PFT patterns. When interpreting PFTs remember that some patients may have combined restrictive and obstructive diseases such as emphysema and asbestosis. OXYGEN AND HUMIDITY SUPPLEMENTS Table 18-2 describes various methods of oxygen and humidity supplementation. TABLE 18-1 Differential Diagnosis of Pulmonary Function Tests Test Restrictive Disease Obstructive Disease FVC r N or r TLC r T FEVi FVC N or T r fev1 r r OBSTRUCTIVE AIRWAYS DISEASE COPD Test Normal Mild Moderate Severe fev1 of VC 75 60-75 40-60 40 RV of predicted 80-120 120-150 150-175 200 RESTRICTIVE LUNG DISEASE Test Normal Mild-Moderate Severe FVC of predicted 80 60-80 50-60 50 FEVi of VC 75 75 75 75 RV of predicted 80-120 80-120 70-80 70 Abbreviations N normal T increased r decreased FVC forced vital capacity TLC total lung capacity RV FRC residual volume functional residual capacity FEVi forced expiratory volume in 1s VC vital capacity. 18 362 Clinician s Pocket Reference 9th Edition TABLE 18-2 Various Methods of Oxygen and Humidity Supplementation 02 Device Range L min F02 Uses Nasal cannula Low 1-6 COPD general oxygen needs Simple face mask Medium 6-8 General oxygen needs Partial rebreathing face mask High 8-12 High oxygen emergency needs Nonrebreathing face mask High 8-12 High oxygen emergency needs Venturi mask Low-medium COPD can specify exact Fi02 Note F 02 may vary with fluctuations in the patient s minute ventilation when using a nasal cannula. This is not true when using the Venturi mask because it is a high-flow oxygen enrichment system that supplies three times the patient s minute ventilation thus providing an exact F 02. Abbreviation COPD .
