Leif Eriksson, MB; by Wollmer, M.D....

Leif Eriksson, MB; by Wollmer, M.D.; Carl-Gustav Olsson, MD; Ulf Albrechtsson, MD; Hrafnhildur Larusdottir, MB; Roma Nilsson, MB; Anders Sjogren MD; and Bjorn Jonson MD

Pulmonary embolism (PE) leads to an abnormal alveolar deadspace that is expired in synchrony with gas from normally perfused alveoli. This feature of PE separates it from pulmonary diseases affecting the airways, which are characterized by the agency of nonsynchronous emptying of compartments with an rough ventilation/perfusion relationship. An analysis of the single breath ordeal (SBT) for [CO.sub.2], SBT-[CO.sub.2], focusing forward the late tidal expirate, was made in order to evaluate the feasibility to use the SBT-[COsub2] for the diagnosis of PE The exhibition was evaluated in 38 patients with suspected PE where pulmonary angiography showed that nine had PE and 29 did not. It was also touchstoneed in a reference population consisting of patients with normal lung function, obstructive lung disease and interstitial lung disease. Previously intimateed gas exchange measurements for the diagnosis of PE ie, the physiologic deadspace fraction, VDphys/VT and the arterial-to-end-tidal [COsub2] gradient, P(a-E')[CO.sub.2], were also evaluated in the assign places tos SBT-[CO.sub.2] achieved a nearly concluded separation between the patients with PE and those without. The other measurements, however, showed a substantial overlap between patients with PE and those with obstructive or interstitial lung disease. The SBT-[COsub2] is simple and potentially widely available and warrants further reflection as a routine technique for the diagnosis of PE

Pulmonary embolism (PE) is a public grave condition. A firm diagnosis cannot be based concerning clinical symptoms and signs,[1] and ventilation-perfusion scintigraphy or pulmonary angiography is generally required to establish the diagnosis. These diagnostic techniques are barely available in larger hospitals, and are expensive and sustained by upon experienced personnel for the performance of the touchstone and interpretation of the conclusions A test is privationed that can be performed and interpreted at the staff of any hospital at bedside. We offer proffer that analysis of dead space through means of the single-breath proof for [CO.sub.2] (SBT-[CO.sub.2]) may be similar a test.[2,3]

The SBT-[COsub2] which entails measurement of the evolution of [COsub2] in a single breath, is shown diagrammatically in Figure 1A. The first portion of the exhaled breath describes air from the airways and contains virtually no [COsub2] (phase I of the SBT-[COsub2] crook in Fig 1). Then run afters a mixture of gas from the airways and alveoli. During this phase of expiration, the concentration of [COsub2] increases rapidly (phase II). The last portion of the exhaled air delineates alveolar gas (phase III, or alveolar plateau). In healthy make subordinates the alveolar gas is in near equilibrium with arterial blood

In pulmonary diseases affecting the airways, there is greater than normal dispersion in alveolar partial squeezing for [CO.sub.2] ([PACO.sub.2]) owing to inhomogenous ventilation-perfusion relationship between lung compartments.[2,4,5] Compartments with high alveolar ventilation and reasonable [PACO.sub.2] empty early in expiration and compartments with soft ventilation and high [PACO.sub.2] late in expiration. This asynchronous emptying of compartments gives rise to an increased obliquity of phase III in the SBT-[COsub2] bend (Fig 1B). The difference between end-tidal and arterial [PCOsub2] P(a-E')[CO.sub.2], is frequently increased.

In pulmonary embolism, affected lung compartments have a self-same low [PACO.sub.2]. These compartments have essentially normal ventilation and unoccupied synchronously with normally perfused compartments. Alveolar gas from normally perfused and ventilated compartments will thus be uniformly mixed with gas from embolized compartments everywhere expiration. The slope of phase III of the SBT-[COsub2] bend is essentially unaffected, but P(a-E')[CO.sub.2] is increased (Fig 1C) in succession the basis of the different features in SBT-[COsub2] it appears possible to separate airways disease from pulmonary embolism.

The aim of the instant study was to examine the usefulness of the SBT-[COsub2] in the diagnosis of PE using pulmonary angiography as a respect method.

MATERIAL AND METHODS

Patients

We studied patients from the department of internal medicine, who instanted with symptoms leading to clinical suspicion of PE The criterion for inclusion in the meditation was an abnormal lung perfusion scan showing the same or more perfusion defects in the lung fields which were not obviously caused according to enlargement of the heart or pleural fluid.

Patients across 75 years of age and patients in whom pulmonary angiography was considered to be associated with an increased risk of complications were exclud Seventeen women and 21 men were studied with lung scintigraphy, SBT-[COsub2] spirometry and pulmonary angiography. Mean age was 58 years, range 27-73 The SBT-[COsub2] was performed within 12 hours and the pulmonary angiography within 24 hours of the pulmonary scintigraphy.