Respiratory distress in patients with central airway obstruction

Introduction  

Patients with respiratory distress due to central airway obstruction (Trachea, carina or main bronchi) are critically ill with impending suffocation. This obstruction is caused by a variety of benign and malignant causes that might be intraluminal, extra luminal or combined.     

The PaCO2 rate of rise in anesthetized patients with airway obstruction

Apneic, anesthetized patients frequently develop airway obstruction or may be disconnected from ventilatory support. The rate of PaCO2 rise is usually assumed to be equal to that of anesthetized humans who are receiving apneic oxygenation. Apneic oxygenation may eliminate CO2 because it requires a continuous O2 flow. The CO2 rate of rise in anesthetized humans with airway obstruction was measured. Fourteen consenting healthy adults were monitored continuously with pulse oximetry and EKG. Enflurane--O2 anesthesia was established for at least 10 minutes with normal PaCO2 without neuromuscular blockade so that anesthesia was deep enough to prevent spontaneous ventilation. Then, patients' tracheal tubes were clamped. Arterial blood samples were obtained before and after 0, 20, 40, 60, 120, 180, 240, and 300 seconds after clamping, provided that oxyhemoglobin saturation exceeded 0.92. The equation that best described the PaCO2 rise was a logarithmic function. Piecewise linear approximation yielded a PaCO2 increase of 12 mmHg during the first minute of apnea, and 3.4 mmHg/minute thereafter. These values should be employed when estimating the duration of apnea from PaCO2 change for anesthetized patients who lack ventilatory support. In addition, it appears that the flows of O2 that most earlier investigators used when delivering apneic oxygenation probably did not eliminate significant CO2 quantities.     

Respiratory mechanics in airways obstruction associated with inspiratory dyspnoea.

Inspiratory muscle strength and the flow and elastic pressure opposing inspiration were measured in seven patients with severe airways obstruction who found inspiration difficult at rest. A comparison was made of measurements obtained from seven normal subjects and five patients with airways obstruction not experiencing inspiratory dyspnoea at rest. Measurements were also obtained when inspiratory dyspnoea was induced in the normal subjects by adding an inspiratory resistance or by voluntarily increasing lung volume. Compared with the controls the inspiratory muscle strength of the patients was reduced but was not significantly less than that of the patients without inspiratory dyspnoea. The pressure required to produce inspiratory flow was significantly greater when inspiratory dyspnoea was present (P = 0-01). However, there was considerable overlap in the pressures of those with and without inspiratory dyspnoea. A better relationship was obtained when muscle strength was considered. The ratio of inspiratory muscle strength to the pressure required to produce flow was 0-24 +/- 0-07 (mean +/- SD) in patient with inspiratory dyspnoea, 0-10 +/- 0-03 in patients without inspiratory dyspnoea, and 0-033 +/- 0-019 in normal subjects. There was no overlap between the two patient groups. The ratios of the normal subjects were increased when inspiratory dyspnoea was induced and, with the exception of two cases, were all above those obtained when inspiratory dyspnoea was absent. Inspiratory dyspnoea was experienced with lower ratios in the normals than in the patients with airways obstruction.     

Urinary retention without subvesical obstruction. Differential diagnostic considerations

Acute urinary retention without subvesical obstruction is associated with neurogenic or nonneurogenic disorders of bladder function. Urodynamic investigations differentiates sensoric and/or motoric disturbances of the micturation. Neurologic and laboratory examinations are necessary to clear the etiology. Symptomatic urological treatment and specific etiological therapy should be used to manage this entity.     

Bronchial responsiveness to inhaled histamine and isoprenaline in patients with airway obstruction

In order to examine the hypothesis that bronchial reactivity to non-specific constrictor stimuli is influenced by the resting tone of the bronchial smooth muscle, the airway responses to inhaled histamine solution and inhaled isoprenaline were measured in 19 patients with airway obstruction. There was a significant positive correlation between the size of the constrictor response to histamine and the dilator response to isoprenaline (r = +0.83; p less than 0.01) as measured by changes in specific airway conductance. Patients with asthma showed greater bronchial reactivity to both histamine and isoprenaline than those with chronic bronchitis, although some patients had changes intermediate between the two extremes.     

Palliation of airway obstruction from tracheobronchial malignancy: use of the CO2 laser bronchoscope

A CO2 laser rigid bronchoscope system has been used to palliate symptoms of a malignancy obstructing the tracheobronchial airway. Fifty-nine endoscopic laser operations (34 patients) were done between 1975 and 1981. Severe dyspnea and obstructive atelectasis were the most common indications for treatment. Contraindications for treatment included extrinsic tracheobronchial compression, widespread distant metastases, rapidly progressing tumors, and highly vascular neoplasms. There were nine primary tracheal malignancies, five metastases from distant sites, and 20 primary lung cancers with tracheobronchial obstructions. Most patients were previously treated with one or more standard modalities (radiation therapy, surgery, and chemotherapy). Removal of airway obstruction was occasionally indicated prior to radiation therapy to facilitate treatment. There were seven instances of complications in this group of patients and one mortality. Most patients (23 of 34) have died from their malignancy. The best palliation was achieved in proximal (tracheal and main stem bronchial), slower growing tumors.     

Volume effect and exertional dyspnoea after bronchodilator in patients with COPD with and without expiratory flow limitation at rest

BACKGROUND: A study was undertaken to investigate whether bronchodilators are associated with less breathlessness at rest and during light exercise in patients with moderate to severe chronic obstructive pulmonary disease (COPD) with resting tidal expiratory flow limitation (EFL; flow limited (FL)) compared with those without EFL (non-flow limited (NFL)). METHODS: Twenty subjects (13 men) of mean (SD) age 65 (8) years (range 43-77) suffering from COPD with forced expiratory volume in 1 second (FEV(1)) 47 (18)% predicted were studied before and after inhalation of salbutamol (400 microg). Routine pulmonary function tests were performed in the seated position at rest. EFL was assessed by the negative expiratory pressure (NEP) method and changes in end expiratory lung volume (EELV) were inferred from variations in inspiratory capacity (IC). Dyspnoea was measured using the Borg scale at rest and at the end of a 6 minute steady state exercise test at 33% of the maximal predicted workload. RESULTS: EFL occurred in 11 patients. Following salbutamol IC did not change in NFL patients but increased by 24% (95% CI 15 to 33) in FL patients (p<0.001). Maximal inspiratory pressure (PImax) improved at EELV from 45 (95% CI 26 to 63) to 55 (95% CI 31 to 79) cm H(2)O (p<0.05) in FL patients after salbutamol but remained unchanged in NFL patients. The workload performed during exercise amounted to 34 (95% CI 27 to 41) and 31 (95% CI 21 to 40) watts (NS) for patients without and with EFL, respectively. After salbutamol, dyspnoea did not change either at rest or during exercise in the NFL patients, but decreased from 0.3 (95% CI -0.1 to 0.8) to 0.1 (95% CI -0.1 to 0.4) at rest (NS) and from 3.7 (95% CI 1.7 to 5.7) to 2.6 (95% CI 1.1 to 4.0) at the end of exercise (p<0.01) in FL patients. CONCLUSIONS: Patients with COPD with EFL may experience less breathlessness after a bronchodilator, at least during light exercise, than those without EFL. This beneficial effect, which is closely related to an increase in IC at rest, occurs even in the absence of a significant improvement in FEV(1) and is associated with a greater PImax.     

Serial studies of 100 patients with chronic airway obstruction in London and Chicago

One hundred patients with chronic airway obstruction, 50 in Chicago and 50 in London, were studied by standardized techniques in 1961. The results of the initial studies, previously reported, showed that the patients in the two cities were similar; using clinical and physiological criteria based on pathological studies, the patients were divided into three types—emphysematous type A, bronchial type B, and an indeterminate type X. The patients were studied again in succeeding years, 1962-65. During this time 26 died, 19 due to their respiratory disease; these 19 patients were initially more breathless, had a higher incidence of cor pulmonale, and had more severe airway obstruction and higher carbon dioxide pressures than the remainder. Type B patients (mortality 36%) had a worse prognosis than either type A (15%) or type X (12%). Of the measurements made, high carbon dioxide pressures were most closely related (p<0·001) to mortality.During the period of follow-up about one-third of the patients who did not die became more short of breath and developed more severe airway obstruction and carbon dioxide retention: about 10% showed definite improvement in symptoms and pulmonary function. The F.E.V._1·0 declined on average by 46 ml./year, 4·8% of the initial value; V.C. declined by 120 ml./year, 4·0% of the initial value; mixed venous Pco₂ increased 1 mm. Hg/year.The changes that occurred during this time confirmed the previously reported similarity between the patients attending the two clinics. Although the incidence of bronchitic exacerbations was similar in the two cities, such illnesses in the London patients led to more frequent and more prolonged incapacity.     

BPH并发与未并发急性尿潴留患者术前血清PSA对比观察

为了解前列腺增生症并发急性尿潴留与未并发发尿潴留者血清前列腺特异性抗原的变化，对２１例ＢＰＨ并发急性尿潴留及２４例ＢＰＨ未并发尿潴留者术前血清ＰＳＡ进行了对比观察。结果显示ＢＰＨ并发急性尿潴留组血清ＰＳＡ异常者占７６．２％，平均血清ＰＳＡ为１４．２μｇ／Ｌ，其中ＰＳＡ〉１０．０μｇ／Ｌ，占５２．４％。     

Significant CO2 retention in children after premedication with Dormicum and Thalamonal

Whereas in adults the use of Innovar for premedication has been abolished, the combination of midazolam and Innovar is still recommended for the premedication of children. This combination may lead to an additional depressive effect on respiration. A prospective, randomized study was performed to evaluate the risk of ventilatory depression. In 36 infants capillary blood gas values were measured pre- and postmedication with either rectal midazolam (0.4 mg/kg) and i.m. Innovar (0.04 ml/kg) or after oral chlorprothixene (2.0 mg/kg). After chlorprothixen the blood gas values did not change, whereas after the combination of midazolam and Innovar pCO2 rose significantly from 35.5 to 43.0 mmHg. In 7 of 22 cases pCO2 reached values above 45 mmHg. This difference compared to the chlorprothixene group was significant (p less than 0.05). The pH fell significantly from 7.42 to 7.36 in the combination group. Clinical signs of respiratory depression could not be observed in this group. The combination of midazolam with Innovar is therefore not useful for premedication in infants and young children.     

Platelet size in patients with chronic airflow obstruction with and without hypoxaemia.

Platelet size, expressed as mean platelet volume, was estimated in 35 patients with chronic airflow obstruction and a wide range of arterial oxygen tension (PaO2) values. In these patients there was a negative correlation between MPV and PaO2 (r = -0.70). Mean platelet volume was greater (9.41 (0.86) fl) in 20 patients with an arterial PaO2 of 8 kPa (60 mm Hg) or less than in 18 normal subjects (8.21 (0.63) fl; p less than 0.001). After 24 hours of supplemental oxygen treatment there was a small fall in mean platelet volume, from 9.47 (1.06) to 8.96 (0.8) fl (p less than 0.05) in 12 hypoxaemic patients (PaO2 breathing air less than or equal to 8 kPa) but no change in nine non-hypoxaemic patients. Larger platelets are considered to be haemostatically more active, leading to abnormal platelet function, which may contribute to the development of pulmonary vascular damage in chronic hypoxaemia. Supplemental oxygen may partially reverse these changes by modifying platelet size and activity.     

Acute airway obstruction, hypertension and kyphoscoliosis

An elderly woman developed acute respiratory obstruction after choking on a bolus of food. On rigid bronchoscopy no foreign body, or anatomical obstruction was seen, but airway obstruction recurred during emergence from general anaesthesia, and was thought to be functional in nature. A recurring airway obstruction followed, relieved by induction of anaesthesia and by sedation. This was subsequently demonstrated to be caused by a tortuous aorta which impinged intermittently on the anterior tracheal wall, as a result of kyphoscoliosis of the thoracic spine. We attribute the relief of airway obstruction by general anaesthesia to a reduction in arterial blood pressure.     

Pattern of carbon dioxide stimulated breathing in patients with chronic airway obstruction

The pattern of stimulated breathing during carbon dioxide inhalation was studied in a group of 21 patients with severe irreversible airways obstruction (mean FEV1 = 0.9 litre, mean FEV1/FVC% = 50%). Carbon dioxide rebreathing experiments were performed, the ventilatory response being defined in terms of total ventilation (V) and CO2 sensitivity (S). Breathing pattern was defined by the changes in tidal volume (delta VT) and respiratory frequency (delta f) and the maximum VT achieved (VTmax). Contrary to some previous studied no significant relationship could be demonstrated between the severity of airway obstruction (FEV1/FVC%, Raw) and the ventilatory response to rebreathing (V, S, delta VT, delta f, VTmax). However, measurements of dynamic lung volume (FEV1, FVC, IC) were found to be significantly correlated with the breathing pattern variables (delta VT, delta f, VTmax). Resting PaO2 and PaCO2 were significantly correlated with delta VT but not delta f. Results indicate that the degree of airway obstruction does not dictate the ventilatory or breathing pattern response to carbon dioxide induced hyperpnoea. In contrast it is the restriction of dynamic lung volume, by limiting the VT response, that appears to determine the ventilatory and breathing pattern response in patients with severe airway obstruction.     

Relationship between peripheral airway dysfunction, airway obstruction, and neutrophilic inflammation in COPD

BACKGROUND: Considerable research has been conducted into the nature of airway inflammation in chronic obstructive pulmonary disease (COPD) but the relationship between proximal airways inflammation and both dynamic collapse of the peripheral airways and HRCT determined emphysema severity remains unknown. A number of research tools have been combined to study smokers with a range of COPD severities classified according to the GOLD criteria. METHODS: Sixty five subjects (11 healthy smokers, 44 smokers with stage 0-IV COPD, and 10 healthy non-smokers) were assessed using lung function testing and HRCT scanning to quantify emphysema and peripheral airway dysfunction and sputum induction to measure airway inflammation. RESULTS: Expiratory HRCT measurements and the expiratory/inspiratory mean lung density ratio (both indicators of peripheral airway dysfunction) correlated more closely in smokers with the severity of airflow obstruction (r = -0.64, p<0.001) than did inspiratory HRCT measurements (which reflect emphysema severity; r = -0.45, p<0.01). Raised sputum neutrophil counts also correlated strongly in smokers with HRCT indicators of peripheral airway dysfunction (r = 0.55, p<0.001) but did not correlate with HRCT indicators of the severity of emphysema. CONCLUSIONS: This study suggests that peripheral airway dysfunction, assessed by expiratory HRCT measurements, is a determinant of COPD severity. Airway neutrophilia, a central feature of COPD, is closely associated with the severity of peripheral airway dysfunction in COPD but is not related to the overall severity of emphysema as measured by HRCT.