ABSTRACT
The detailed mechanisms of oxygen-induced hypercapnia were examined in 22 patients during an acute exacerbation of chronic obstructive pulmonary disease. Ventilation, cardiac output, and the distribution of ventilation-perfusion (V A/Q ) ratios were measured using the multiple inert gas elimination technique breathing air and then 100% oxygen through a nose mask. Twelve patients were classified as retainers (R) when Pa(CO(2)) rose by more than 3 mm Hg (8.3 +/- 5.6; mean +/- SD) after breathing 100% oxygen for at least 20 min. The other 10 patients showed a change in Pa(CO(2)) of -1.3 +/- 2.2 mm Hg breathing oxygen and were classified as nonretainers (NR). Ventilation fell significantly from 9.0 +/- 1.5 to 7.2 +/- 1.2 L/min in the R group breathing oxygen (p = 0.007), whereas there was no change in ventilation in the NR group (9.8 +/- 1.8 to 9.9 +/- 1.8 L/min). The dispersion of V A/Q ratios as measured by log SD of blood flow (log SD Q) increased significantly in both R (0.96 +/- 0. 17 to 1.13 +/- 0.17) and NR (0.77 +/- 0.20 to 1.04 +/- 0.23, p < 0.05) groups breathing oxygen, whereas log SD of ventilation (log SD Q ) increased only in the R group (0.97 +/- 0.24 to 1.20 +/- 0.46, p < 0.05). This study suggests that an overall reduction in ventilation characterizes oxygen-induced hypercapnia, as an increased dispersion of blood flow from release of hypoxic vasoconstriction occurred to a significant and similar degree in both groups. The significant increase in wasted ventilation (alveolar dead space) in the R group only may be secondary to the higher carbon dioxide tension, perhaps related to bronchodilatation.
Subject(s)
Hypercapnia/etiology , Lung Diseases, Obstructive/physiopathology , Oxygen Inhalation Therapy/adverse effects , Ventilation-Perfusion Ratio , Acute Disease , Aged , Air , Female , Humans , Hypercapnia/physiopathology , Lung Diseases, Obstructive/therapy , Male , Middle Aged , Pulmonary Gas ExchangeSubject(s)
Lung Diseases, Obstructive/physiopathology , Positive-Pressure Respiration , Pulmonary Gas Exchange , Acute Disease , Carbon Dioxide/blood , Female , Humans , Lung Diseases, Obstructive/therapy , Male , Respiratory Insufficiency/etiology , Respiratory Insufficiency/physiopathology , Respiratory Insufficiency/therapyABSTRACT
A 37-yr-old man with pulmonary alveolar microlithiasis (PAM) presented with respiratory failure and cor pulmonale. The FEV1/FVC was 1.4/1.8 L with total lung capacity of 3.2 L using the helium dilution method (54% predicted) and 6.1 L using body plethysmography (102% predicted), indicating large noncommunicating regions. The KCO (transfer factor per liter lung volume) was 3.05 ml/min/mm Hg/L (47% predicted). Despite home oxygen (3 L/min) and diuretic therapy, the patient remained hypoxic (PaO2, 55 mm Hg) and incapacitated with dyspnea. Nasal continuous positive airway pressure (nCPAP) at 12 cm H2O and oxygen at 1 L/min improved his oxygenation (PaO2, 93 mm Hg), and introduction of this regimen at night resulted in subjective improvement in daytime function. A Grandjean right heart catheter was introduced at the bedside, and the multiple inert gas elimination technique (MIGET) was used to measure ventilation and blood flow distributions at ambient pressure and with the addition of 10 cm H2O nCPAP. The patient had severe pulmonary hypertension (mean Ppa, 57 mm Hg) and severe hypoxemia (PaO2 37 mm Hg), which was mainly due to shunt (16% of cardiac output) and a broadening of the main mode of the ventilation-perfusion (VA/Q) distribution (log SD Q, 0.94). There was a significant reduction in shunt during nCPAP to 6% of cardiac output without increasing Ppa, and this effect appeared to extend past the period of application. We conclude that nCPAP reduces intrapulmonary shunt in this rare condition and allows for correction of hypoxemia with a smaller oxygen flow rate.
Subject(s)
Calculi/therapy , Lung Diseases/therapy , Positive-Pressure Respiration , Pulmonary Fibrosis/therapy , Pulmonary Gas Exchange , Adult , Calculi/genetics , Humans , Lung Diseases/genetics , Male , Pulmonary Fibrosis/etiologyABSTRACT
This is a case report of multiple septic complications of a peripheral intravenous cannula as a direct result of proximal embolization of a fragment of the cannula to the heart and major vessels.
Subject(s)
Catheterization, Peripheral/adverse effects , Foreign Bodies/complications , Staphylococcal Infections/etiology , Aged , Embolism/etiology , Endocarditis, Bacterial/etiology , Equipment Failure , Female , Foreign Bodies/diagnostic imaging , Humans , Pleural Effusion/diagnostic imaging , Pleural Effusion/etiology , Pulmonary Artery/diagnostic imaging , Radiography , Sepsis/etiologyABSTRACT
Studies are reported of four patients (all lifetime non-smokers) who presented with right heart failure as a consequence of unrelieved asthmatic airways obstruction. These patients demonstrated severe airways obstruction with crackles on auscultation and hypercapnia. As shown here, such a presentation, without the usual pattern of dyspnoea and wheeze, tends to obscure the diagnosis and delays effective treatment. In three of the patients, treatment to relieve airways obstruction improved gas exchange, and the heart failure resolved. In the remaining patient, improvement was limited, and death ensued from respiratory failure. In patients who present with right heart failure, a relationship with airways obstruction and respiratory failure should be considered and assessed by objective tests. Delays in the effective treatment of these patients may result in the progression of their disease to a stage at which airways obstruction no longer responds to medical therapy.
