Medical Inspection – Health Blog

Patients

Eight male patients (x ± SEM, 62 ±1 year) with the standard clinical criteria of COPD and with previous functional confirmation of nonreversible chronic airflow limitation (FEV„ 1.15 ±0.12 L [36 ±3 percent predicted]) were selected from the outpatient clinic of our institution. None of them had clinical evidence of overt right heart failure. Type В COPD was present in five patients whereas the three remaining patients had predominantly type A COPD. Consent was obtained after the purposes and risks of the investiga­tion were explained and understood by each patient. All were clinically stable (none had required hospitalization during the previous two months) and none had evidence of renal, liver, or intrinsic heart disease. None of them was receiving oxygen therapy at home. Pulmonary function test (PFT) evaluation included meas­urement of static and dynamic lung volumes (HF-47804A Pulmonary System Desk; Hewlett-Packard, Palo Alto, Calif), plethysmography functional residual capacity and airway resistance (Body test, E. Jaeger, WUrzburg, FRC), and single-breath carbon monoxide dif­fusing capacity (Deo) (Resparameter model A, PK Morgan Ltd, Chatham, UK). The Deo values were corrected for hemoglobin. Predicted values for PFT were from our own laboratory.

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To patients with chronic obstructive pulmonary dis­ease (COPD) studied at rest, nifedipine releases hypoxic pulmonary vasoconstriction (HPV), diverts blood flow to poorly ventilated lung units, and worsens gas exchange. During exercise, release of HPV in COPD by nifedipine blunts the increase in pulmonary artery pressure (Ppa) and lowers the severity of pulmonary hypertension. However, the effects of this lower pulmonary vascular tone on ventilation- perfusion (Va/Q) relationships under exercise condi­tions are still poorly understood. This investigation was aimed at analyzing the role of hypoxic vasocon­striction in modulating pulmonary gas exchange dur­ing exercise in COPD. We used the multiple inert gas elimination technique to determine the Va/Q distri­butions of eight patients with COPD at rest and during exercise, before and after releasing HPV by nifedi­pine. Read More…

Bronchoalveolar lavage is often used in adult pa­tients for a variety of diagnostic purposes. In children, standards for technique, as well as normal values, have yet to be defined. There are several potential pitfalls. If the tip of the bronchoscope is not wedged into an airway, much of the saline solution instilled through the suction channel may be distributed into adjacent or proximal airways, leading to coughing, aspiration of fluid into other areas of the lungs, and loss of specimen volume. The suction channel (in Olympus broncho­scopes) is located at 2 o’clock from the marker on the circumference of the bronchoscope image which iden­tifies the plane of flexion. The lumen of the airway into which the tip of the instrument is wedged should be positioned to the upper right of the image. Total lavage volumes must be sufficient to permit the necessary diagnostic studies, but should not be exces­sive, as this may lead to respiratory compromise.

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Bronchoscopists, especially pediatric bronchosco­pists, cannot be medical unitarians. Children fre­quently have multiple abnormalities in their airways. Even when a finding explains the child’s symptoms, other abnormalities may lurk around the corner. For example, in 15 percent of children whom I have examined for stridor and in whom a plausible expla­nation for the stridor was found at the subglottis or above, there was in addition a significant lesion in the trachea or bronchi. Unless there are good reasons not to do so, a thorough examination should be made of the entire airway during each examination.

When multiple lesions are found, it can sometimes be difficult to determine which lesion is most impor­tant or contributes most to the patients problem. This may usually be resolved by careful observation under conditions which most nearly mimic those under which the symptoms occur and by paying careful attention to physiologic principles.

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Inadequate or inappropriate monitoring of the pa­tient during the procedure is another major potential pitfall. Bronchoscopy is fun and interesting. Often everyone in the bronchoscopy suite becomes so en­grossed in the endoscopic findings that it is easy to forget about the patient and his physiologic status. Bronchoscopists hypnosis is a real phenomenon! Even with otherwise appropriate electronic monitoring, the patient must be continuously observed by someone other than the bronchoscopist.

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Bronchoscopy may be very helpful in the evaluation of a patient with lower airway infection, especially if there are unusual features of the clinical picture or if the patient cannot produce sputum. However, just as expectorated material may not be representative of the lower airways, or may be contaminated with upper airway or oral secretions, specimens obtained with a bronchoscope must be subjected to serious scrutiny. Pediatric flexible bronchoscopes are too small to use currently available protected microbiology specimen brushes, so bacteriologic specimens must be obtained by aspiration, with or without saline solution lavage. Great care must be taken to avoid contamination of the instrument with nasal or oral secretions; this is not always possible. Excessive use of topical lidocaine solution can wash oral secretions into the lower airways, and lidocaine can be bacteriostatic itself. It is useful to compare a specimen obtained from the oropharynx with bronchial washings (nonbacteriostatic saline solution must be used for washings), and also to use quantitative cultures. The cytology of the washings should be studied; a polymicrobial specimen contain­ing few polymorphonuclear leukocytes does not likely indicate lower airway infection.

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Abnormal airway dynamics (laryngomalacia, trache­omalacia, bronchomalacia) are frequently seen during pediatric bronchoscopy. One must be careful not to overdiagnose dynamic changes in airway caliber as pathologic states. In general, one should be able to visualize change in the airway size sufficient to cause symptoms before making a diagnosis of tracheomalacia or bronchomalacia. In other words, one should see the opposite walls of the airways touch or nearly touch each other, at least during coughing. The presence of the flexible bronchoscope may increase airway resis­tance to the point that normal dynamics are exagger­ated. Therefore, the diagnosis should also be consistent with the clinical history of the patient or radiographic findings. A patient suspected of having tracheomalacia or bronchomalacia must also be ex­amined under conditions which will produce sufficient changes in intrathoracic pressure to demonstrate the abnormal airway dynamics. I have seen a number of children who had very significant airway collapse during flexible bronchoscopy but in whom rigid bron­choscopy under general anesthesia failed to demon­strate any abnormality. Likewise, children with stridor should usually be examined while they are stridu­lus—the vibrating structures should then always be visible.

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