George Cremona

Pulmonary extravascular fluid accumulation in recreational climbers: a prospective study

BACKGROUND High altitude pulmonary oedema (HAPE) that is severe enough to require urgent medical care is infrequent. We hypothesised that subclinical HAPE is far more frequent than suspected during even modest climbs of average effort. METHODS We assessed 262 consecutive climbers of Monte Rosa (4559 m), before ascent and about 24 h later on the summit 1 h after arriving, by clinical examination, electrocardiography, oximetry, spirometry, carbon monoxide transfer, and closing volume. A chest radiograph was taken at altitude. FINDINGS Only one climber was evacuated for HAPE, but 40 (15%) of 262 climbers had chest rales or interstitial oedema on radiograph after ascent. Of 37 of these climbers, 34 (92%) showed increased closing volume. Of the 197 climbers without oedema, 146 (74%) had an increase in closing volume at altitude. With no change in vital capacity, forced expiratory volume in 1 s and forced expiratory flow at 25-75% of forced vital capacity increased slightly at altitude, without evidence of oedema. If we assume that an increased closing volume at altitude indicates increased pulmonary extravascular fluid, our data suggest that three of every four healthy, recreational climbers have mild subclinical HAPE shortly after a modest climb. INTERPRETATION The risk of HAPE might not be confined to a small group of genetically susceptible people, but likely exists for most climbers if the rate of ascent and degree of physical effort are great enough, especially if lung size is normal or low.

Diagnosis and treatment of traumatic pulmonary pseudocysts.

BACKGROUND Traumatic pulmonary pseudocysts (TPPs) are rare sequelae of blunt chest trauma. We present a retrospective review of TPPs observed in our hospital and discuss the diagnosis, treatment, and complications of these unusual lesions. METHODS Between 1991 and 1999, 11 TPPs were diagnosed in 10 patients. None of the lesions was detectable on the chest radiograph obtained on the day of injury. In contrast, computed tomographic scan of the chest always demonstrated the TPPs. RESULTS In nine cases, spontaneous healing of the lesions was observed. One patient with a large lesion of the left lower lobe developed significant endobronchial bleeding and underwent successful emergency lobectomy. CONCLUSION TPPs are often missed by chest radiography, particularly when it is obtained in the supine position, whereas computed tomographic scan allows the identification of these lesions in all cases. TPPs are self-limiting, benign lesions that usually require no specific therapy. Surgical treatment is indicated in rare instances and only when complications occur.

Hemodynamic Effects of Basal and Stimulated Release of Endogenous Nitric Oxide in Isolated Human Lungs

Background-We compared the hemodynamic responses to inhibition or stimulation of endothelial nitric oxide (NO) release of isolated explanted lungs from transplantation recipients with pulmonary hypertension and in normotensive unallocated donor lungs. Methods and Results-Lungs from 10 patients with severe pulmonary hypertension (SPH) and from 16 patients with severe chronic obstructive lung disease (COLD) were studied. Fourteen normotensive lungs were studied as controls. The lungs were perfused at a constant flow. In protocol 1 N(G)-nitro-L-arginine methyl ester caused a similar rise in baseline pulmonary artery pressure (PAP) that was similar in SPH (+17.1+/-4.2 mm Hg; n=5), COLD (+15.5+/-4.8 mm Hg; n=8), and control lungs (+14.5+/-1.5 mm Hg; n=7). Arterial occlusion demonstrated that most of the changes with N(G)-nitro-L-arginine methyl ester were precapillary. The response to sodium nitroprusside (10(-8) to 10(-4) mol/L) was similar in all groups. In protocol 2, the lungs were preconstricted, and acetylcholine (10(-9) to 10(-5) mol/L) caused a lesser fall in PAP in both COLD and SPH lungs compared with control (-41.9+/-8.6%, -55. 7+/-7.6%, and -73.2+/-2.5%, respectively; P<0.05), whereas sodium nitroprusside (10(-5) mol/L) decreased PAP to initial levels in all lungs. Conclusions-Stimulated release of NO is impaired in arteries of lungs with plexogenic or hypoxemic pulmonary hypertension. In contrast, basal release of NO appears to be maintained.

Peripheral baroreflex and chemoreflex function after eversion carotid endarterectomy

OBJECTIVE This study assessed the long-term effect of the eversion technique for carotid endarterectomy (e-CEA) on arterial baroreflex and peripheral chemoreflex function. METHODS The study included 13 patients who underwent, between 2001 and 2006, bilateral e-CEA and 16 who underwent bilateral standard CEA (s-CEA) to eliminate the complicating effects of intact contralateral carotid sinus function. Exclusion criteria were age >70 years, diabetes mellitus, chronic pulmonary disease, ischemic cardiac disease or medical therapy with β-blockers, cardiac arrhythmia, neurologic deficits, carotid restenosis, and previous neck or chest surgery or irradiation. Young and aged-matched healthy individuals were recruited as controls. All patients underwent standard cardiovascular reflex tests, including lying-to-standing, orthostatic hypotension, deep breathing, and Valsalva maneuver. Autonomic cardiovascular modulation was indirectly evaluated by spectral analysis of heart rate variability and systolic arterial pressure variability. The chemoreflex sensitivity to hypoxia was obtained during classic rebreathing tests from the slopes of the linear regression of minute ventilation (VE) vs arterial oxygen saturation measured by pulse oximetry (SpO2%) and partial pressure of end-tidal oxygen (PetO2). RESULTS Patients (16 men; age, 62.4 ± 8.0 years) were enrolled after a mean interval of 24 ± 17 months from the last CEA. All were asymptomatic, and results of standard tests were negative. Residual baroreflex performance was documented in both patient groups, although reduced, compared with young controls. Notably, baroreflex sensitivity (msec/mm Hg) was better maintained after e-CEA than after s-CEA at rest (young controls, 19.93 ± 9.50; age-matched controls, 7.75 ± 5.68; e-CEA, 13.85 ± 14.54; and s-CEA, 3.83 ± 1.15; analysis of variance [ANOVA], P = .001); and at standing (young controls, 7.83 ± 2.55; age-matched controls, 3.71 ± 1.59; e-CEA, 7.04 ± 5.62; and s-CEA 3.57 ± 3.80; ANOVA, P = .001). Similarly, chemoreflex sensitivity to hypoxia was maintained in both patient groups, which did not differ from each other, and was reduced compared with controls (controls vs patient groups ΔVE/ΔSpO2: -1.37 ± 0.33 vs -0.33 ± 0.08 and SpO2% -0.29 ± 0.13 L/min; P = .002; ΔVE/ΔPetO2: -0.20 ± 0.1 vs -0.01 ± 0.0 and -0.07 ± 0.02 L/min/mm Hg; P = .04, ANOVA with least significant difference correction for multiple comparisons). CONCLUSIONS Our data show that e-CEA, even when performed on both sides, preserves baroreflexes and chemoreflexes and, therefore, does not confer permanent carotid sinus denervation. Also, e-CEA does not increase long-term arterial pressure variability, and this suggests that perioperative hemodynamic derangements can be attributed to the temporary effects of surgical trauma.

Exhaled nitric oxide after inhalation of isotonic and hypotonic solutions in healthy subjects.

Airway nitric oxide (NO) homoeostasis is influenced by chemical and mechanical stimuli in humans; airway epithelium, which is an important site of NO production, is sensitive to osmotic challenge. The effect of inhaled hypotonic solutions on exhaled NO (eNO) is not known. In this study we evaluated the effect of ultrasonically nebulized distilled water (UNDW), a hypotonic indirect stimulus, on eNO levels. A total of 10 non-smoking healthy subjects were enrolled in the study. eNO was detected by chemiluminescence, and specific airway conductance (sGaw) was measured by plethysmography. Bronchial challenges with UNDW and with an isotonic solution were performed according to a double-blind experimental design. Baseline levels of eNO were 28.1+/-14.7 p.p.b. UNDW did not cause any significant change in sGaw (from 0.190+/-0.029 to 0.181+/-0.036 cm H(2)O x s(-1)). With respect to baseline values, the eNO concentration decreased significantly after inhalation of 8 or 16 ml of UNDW (from 26.0+/-13.1 to 17.2+/-8.5 and 16.6+/-7.7 p.p.b. respectively; P<0.001, n=10). After bronchial challenge with UNDW, eNO was significantly reduced in comparison with after inhalation of the isotonic solution. In five subjects, pretreatment with N(G)-nitro-L-arginine methyl ester (L-NAME), an inhibitor NO synthesis, decreased NO levels from 21.7+/-8.5 to 10.0+/-3.3 p.p.b. Subsequent inhalation of 16 ml of UNDW did not cause any further decrease in NO levels (10.1+/-3.7 p.p.b.; not significant compared with L-NAME). We conclude that inhalation of aqueous solutions decreases eNO levels in healthy subjects, and that this effect is not associated with any significant change in airway calibre. The UNDW-induced decrease in eNO is not enhanced by pretreatment with the NO synthase inhibitor L-NAME, suggesting that inhaled solutions may interfere with the airway NO pathway in humans.

Mechanisms of gas exchange response to lung volume reduction surgery in severe emphysema

Lung volume reduction surgery (LVRS) improves lung function, respiratory symptoms, and exercise tolerance in selected patients with chronic obstructive pulmonary disease, who have heterogeneous emphysema. However, the reported effects of LVRS on gas exchange are variable, even when lung function is improved. To clarify how LVRS affects gas exchange in chronic obstructive pulmonary disease, 23 patients were studied before LVRS, 14 of whom were again studied afterwards. We performed measurements of lung mechanics, pulmonary hemodynamics, and ventilation-perfusion (Va/Q) inequality using the multiple inert-gas elimination technique. LVRS improved arterial Po₂ (Pa(O₂)) by a mean of 6 Torr (P = 0.04), with no significant effect on arterial Pco₂ (Pa(CO₂)), but with great variability in both. Lung mechanical properties improved considerably more than did gas exchange. Post-LVRS Pa(O₂) depended mostly on its pre-LVRS value, whereas improvement in Pa(O(2)) was explained mostly by improved Va/Q inequality, with lesser contributions from both increased ventilation and higher mixed venous Po(2). However, no index of lung mechanical properties correlated with Pa(O₂). Conversely, post-LVRS Pa(CO₂) bore no relationship to its pre-LVRS value, whereas changes in Pa(CO₂) were tightly related (r² = 0.96) to variables, reflecting decrease in static lung hyperinflation (intrinsic positive end-expiratory pressure and residual volume/total lung capacity) and increase in airflow potential (tidal volume and maximal inspiratory pressure), but not to Va/Q distribution changes. Individual gas exchange responses to LVRS vary greatly, but can be explained by changes in combinations of determining variables that are different for oxygen and carbon dioxide.

Direct Estimation of General Pulmonary Vascular Models from Occlusion Experiments

Occlusion experiments yield time–pressure and time–flow curves which are related to the longitudinal distribution of compliances and resistances in the pulmonary circulation. The standard approach to the analysis of these curves involves the observation of relevant features of their graphs, which may directly reflect model parameter values. The present work considers five possible models of pulmonary vascular pressure dynamics and the relative (nonlinear) least-squares parameter estimation from experimental data, making simultaneous use of all available information. In situ isolated perfused and ventilated pig lung preparations were used, and pressure and flow changes during arterial, double, and venous occlusion maneuvers were measured. The five models considered included two linear models without inductance units, one linear model with inductance units, one nonlinear model with variable resistance, and one nonlinear model with variable compliance. In all cases parameter estimation for the numerically integrated model was performed by unweighted least squares, using a variable-metric minimization technique. Comparisons between competing models were based on parameter identifiability and on the Akaike Information Criterion (AIC), concluding that significant nonlinearity in the response of the pig lung resistance to variations in pressure is present for the analyzed data sets.

Solitary Fibrous Tumour of the Pleura Presenting as a Spontaneous Massive Haemothorax

Solitary fibrous tumours of the pleura are rare neoplasms. These tumours are generally asymptomatic and incidentally diagnosed. Symptoms, if present, are nonspecific such as cough, dyspnea, and chest pain. This report describes the case of a 38-year-old woman admitted to our department after the onset of a right massive spontaneous haemothorax requiring emergency surgical treatment. Intraoperatively a bleeding pleural mass was found to be the cause of the haemothorax. The tumour was successfully resected and the patient made an uneventful recovery. Histological examination revealed the mass to be a solitary fibrous tumour of the pleura.