Adult cystic fibrosis care in the 21st century

Cystic fibrosis (CF) is the most common autosomal recessive inherited disease of Caucasian populations. As a result of a variety of diagnostic and therapeutic strategies there has been a dramatic increase in the life expectancy of patients with CF in the last decades and 50% of patients are now adults. This review will focus on the disease in adults and the provision of appropriate care. The complex care required to improve the survival and quality of life in the adult patients can best be provided in a dedicated adult cystic fibrosis unit. These units currently exist in many European countries, but more are needed in Italy.

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.

Exhaled nitric oxide in patients with PiZZ phenotype-related alpha1-anti-trypsin deficiency

There is no report of exhaled NO (eNO) in subjects with different phenotypes of alpha1-anti-trypsin (AAT) deficiency. Exhaled nitric oxide was evaluated by means of single-breath chemiluminescence analysis (fractional exhaled concentration at the plateau level [plFE(NO)]) in 40 patients with AAT deficiency. Patients were divided according to the protease inhibitor (Pi) phenotype: PiMZ/MS, n = 25; PiSZ n = 6; PiZZ, n = 9. Nineteen healthy subjects served as controls. Levels of eNO in PiZZ patients were also compared with those of subjects, without AAT deficiency (PiMM), matched for diagnosis, sex, age, smoking habit and forced expiratory volume in 1 sec (FEV1). In AAT deficiency subjects airway hyper-responsiveness to methacholine (PD20 FEV1) was also assessed. plFE(NO) was significantly lower in the PiZZ group (4.5+/-1.4 ppb) than in matched PiMM subjects (8.2+/-3.8 ppb), in healthy controls (9.3+/-2.8 ppb) and in patients of other phenotypes. Dynamic lung volumes and DL(CO) were significantly lower in PiZZ than in other AAT-deficient patients. Bronchial hyper-responsiveness was not different among AAT phenotypes. These results suggest that eNO may be significantly reduced in PiZZ as compared to healthy control subjects and to AAT subjects with other phenotypes, independent of the level of airway obstruction. Whether, at least potentially, eNO may be considered as an early marker of lung involvement in AAT deficiency must be confirmed with studies on larger number of subjects.

Revascularization of severe hibernating myocardium in the beating heart: early hemodynamic and metabolic features

BACKGROUND

We investigated the effects of coronary artery bypass grafting (CABG) without cardiopulmonary bypass (CPB) in selected patients with severe hibernating myocardium.

METHODS

Twelve patients (EF = 25% +/- 0.7%) with reversible ventricular dysfunction (from 2.0 +/- 0.06 to 1.6 +/- 0.05 left ventricular score index by echodobutamine, p < 0.01) in the territory of the left anterior descending artery (LAD) have been studied. Revascularization was achieved by anastomosing the left internal mammary artery to the LAD. The ischemic time of LAD was 9.0 +/- 0.4 minutes.

RESULTS

Left ventricular function increased 6 hours and 48 hours after revascularization (left ventricular stroke work index from 32 +/- 1.8 to 42 +/- 1.5 and 40 +/- 0.6 gxm/m2, respectively: p = 0.0001). During the surgical procedure, the heart did not release lactate or creatine phosphokinase. There were no perioperative deaths or severe complications.

CONCLUSIONS

Early hemodynamic and metabolic features of CABG without CPB in patients with hibernating myocardium suggest that this procedure is safe and results in a significant improvement of cardiac function without affecting myocardial metabolism.

Smoothness of Ablation on Acrylic by Four Different Excimer Lasers

PURPOSE

There are many different excimer laser devices available for photoablative refractive surgery. Smoothness of ablation may vary with different excimer lasers systems.

METHODS

Ablations were performed on polymethylmethacrylate (PMMA) plates of 8 x 4 x 0.5 cm, with four different excimer lasers: VISX-Star, Coherent Schwind Keratom I/II, Chiron Technolas Keracor 117C (Plano Scan), and the Nidek EC-5000, to determine and compare the homogeneity and smoothness of the surface. Ten -3.00 D samples, ten -6.00 D samples, and ten -9.00 D samples were ablated with each laser. The PMMA discs were examined with optical microscopy, documented by photographs, and each sample was measured quantitatively using a Hommel-Werkel rugosimeter. We used the same PMMA material throughout.

RESULTS

Statistically significant differences in smoothness were found between the Chiron Technolas 117C and the VISX-Star, Nidek and VISX-Star, and Coherent Schwind and VISX-Star in the homogeneities achieved by ablating -3.00 D. Ablations of -6.00 D resulted in homogeneities that were statistically significantly different: Chiron Technolas 117C with the other three devices, the Nidek EC-5000 with the VISX-Star, and the Coherent-Schwind with the VISX-Star. In the ablations for -9.00 D, statistically significant differences in homogeneity were found between the Chiron Technolas 117C and Nidek, between the Chiron and VISX-Star, between the Coherent Schwind and VISX-Star, and between the Nidek and VISX-Star. The laser with the scanning spot system was smoother.

CONCLUSION

Scanning spot technology produced smooth ablations even up to -9.00 D.

Hydrodissection after nucleus fracture

We introduce a technique of hydrodissection that reduces capsular bag distension and thus lowers the risk of capsular block syndrome. In 100 consecutive cases in which this method was used for cataract surgery, no complications occurred. Postoperative best corrected visual acuity was better than 20/40 in 96% of patients.

Production of endogenous nitric oxide in chronic obstructive pulmonary disease and patients with cor pulmonale. Correlates with echo-Doppler assessment

Exhaled nitric oxide (NO) production in stable chronic obstructive pulmonary disease (COPD) has been loosely related to the severity of illness, being significantly reduced in the most severe cases. Pulmonary hypertension is associated with lower NO output from the lung. In this study expired NO was measured in patients with severe stable COPD with or without cor pulmonale (CP). Echocardiographic estimates of right heart function, lung function, diffusion capacity, respiratory muscle strength, and arterial blood gases were obtained in 34 consecutive patients with stable COPD (mean age, 68 +/- 7 yr). Expired NO was measured by chemiluminiscence to obtain fractional exhaled concentrations at peak (FENOp) and at plateau (FENOpl) points of the single-breath curve and resting NO output (V NO). All measurements of expired NO output, FENOp, FENOpl and V NO showed a negative correlation with both systolic pulmonary artery pressure (Pspa) (r = -0.51, -0.63, and -0.63, respectively, p < 0.01 for all) and right ventricle wall dimension (r = -0.41, -0.59, and -0.43, respectively, p < 0.05 for all), but not with any measurement of lung function. When the patients were divided according to the Pspa using a cutoff limit of 35 mm Hg, those subjects with CP showed lower FENOp (13.2 +/- 4.0 versus 36.7 +/- 30.8 ppb, p < 0.05), FENOpl (5.7 +/- 1.9 versus 8.9 +/- 4.7 ppb, p < 0.05), and V NO (69. 2 +/- 5.6 versus 107.6 +/- 14.6 nl/ min, p = 0.02) than did those with a normal resting Pspa. NO production from the airways was significantly lower and inversely related to development of CP in patients with severe COPD. Impaired endothelial release may account for the reduced levels of expired NO.

The acute effects of dexfenfluramine on human and porcine pulmonary vascular tone and resistance

STUDY OBJECTIVES

Treatment with anorectics has become an important aspect of care for the severely obese. One such anorectic, the phenylethylamine dexfenfluramine (dFen), has been associated with the development of pulmonary hypertension. It works by reducing the neuronal uptake of 5-hydroxytryptamine (5-HT; serotonin) through inhibition of the 5-HT transporter. In this study we investigated whether dFen has a direct vasoconstrictor action on human and porcine pulmonary vasculature.

DESIGN

For the human study, tissue was obtained from patients who had undergone lung and heart-lung transplantation. The effect of dFen was studied in seven isolated colloid perfused human lungs and in rings of human pulmonary artery (PA) dissected from the lungs of a further 19 patients. For the porcine study, regional pulmonary vascular resistances (PVRs) were measured in isolated perfused porcine lungs. Vasoconstriction was assessed following dFen alone and in combination with hypoxia, cyclo-oxygenase blockade (indomethacin, 10(-5) mol/L), or nitric oxide synthase (NOS) blockade (N(G)-nitro-L-arginine, 10(-5) mol/L).

RESULTS

In the human study, 5-HT and dFen caused only limited increases in tension of isolated rings of PA. The concentration of dFen, 10(-4) mol/L, that was needed to increase tension was higher than that found normally in treated patients where peak levels are 3. 3 x 10(-7) mol/L. Other vasoconstrictors such as prostaglandin F(2)alpha, 10(-5) mol/L, and the thromboxane analog U46619, 10(-6) mol/L, produced far greater increases in tension. Ketanserin, 10(-4) mol/L, attenuated the constrictor response to 5-HT but had no effect on the constrictor response to dFen. Removal of the endothelium did not influence the response to dFen. In the isolated ventilated and perfused lungs, dFen caused an increase in PVR again only at a comparatively high concentration, 10(-4) mol/L. In the porcine study, dFen, 10(-4) mol/L, did not increase any PVR during normoxia or following NOS blockade. Small insignificant increases in PVR occurred during hypoxia and after cyclo-oxygenase blockade.

CONCLUSION

These results do not support the view that dFen would act as a direct vasoconstrictor when given in the usual doses. However, delayed elimination of dFen could raise tissue concentrations to high levels and give rise to vasoconstriction and pulmonary hypertension.

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.

High-dose heparin impairs nitric oxide pathway and vasomotion in rats

BACKGROUND

Platelet-activating effects have been reported with high-dose heparin in acute thrombotic disorders. Recent studies have shown that increased platelet aggregation is due to reduced nitric oxide (NO) production in endothelial cells cultured in the presence of high-dose heparin. The aim of this study was to determine whether heparin can affect the NO pathway and the regulation of the vascular tone in vivo.

METHODS AND RESULTS

Anesthetized and mechanically ventilated Sprague-Dawley rats were treated with high-dose heparin. After 4 hours, the endothelial constitutive NO synthase (ecNOS) protein content in the aorta decreased (36% reduction, P<0.05), as detected by immunoblotting, and NO-dependent vascular reactivity was impaired. In fact, the increase in mean arterial blood pressure after inhibition of ecNOS with NG-nitro-L-arginine methyl ester (30 mg/kg) was smaller in heparin-treated animals than in controls (+26. 9+/-4.8 versus +48.3+/-9.1 mm Hg, P<0.05), and further infusion of the biological ecNOS substrate L-arginine (0.5 g/kg) was ineffective in reversing systemic vasoconstriction (-1% versus 28% vasodilatation, P<0.001).

CONCLUSIONS

High-dose heparin can significantly affect vascular reactivity in vivo by downregulation of ecNOS protein expression.

Detection of nitric oxide in exhaled air of different animal species using a clinical chemiluminescence analyser

The aim of the present study was to evaluate the nitric oxide (NO) concentrations present in end-expired gas (FENO) of different animal species under basal and stimulated conditions using a clinical chemiluminescence analyser, which has been developed for measurement of single exhalations in humans. Anaesthetised, tracheotomised and artificially ventilated guinea pigs, rats and rabbits were prepared for recording systemic blood pressure and FENO. Stable levels of FENO were detected in expired air over a 1-h observation period in the three animal species tested. Rabbits exhibited the highest concentrations and output (FENO 12.9+/-1.0 ppb, VNO 9.0+/-0.7 nl min-1), followed by guinea pigs (FENO 6.2+/-0.70 ppb, VNO 1.7+/-0.19 nl min-1) and rats (FENO 0.9+/-0.01 ppb, VNO 0.25+/-0.00 nl min-1). L-arginine (1 g kg-1 i.v.) evoked significant increments in VNO in guinea pigs and rabbits but was ineffective in rats. However, L-arginine showed a direct effect on blood pressure in all the animal species tested, causing a rapid fall in the mean arterial blood pressure (MABP; 38, 48 and 50% decrease in rabbits, guinea pigs and rats, respectively; P<0.05). An inhibitor of endogenous NO synthesis, NG-nitro-L-arginine methyl ester (L-NAME, 20 mg kg-1 i.v.), decreased both basal and L-arginine-induced VNO in guinea pigs and rabbits, but was ineffective in rats. L-NAME increased MABP in all the animal species tested (58% in guinea pigs, 43% in rats and 18% in rabbits; P<0.05). The results indicate that it is possible to detect NO in the exhaled air of different animal species using a clinical chemiluminescence analyser and that different species exhibit striking differences in the levels of basal and stimulated NO output.

Minimizing the inhaled dose of NO with breath-by-breath delivery of spikes of concentrated gas

BACKGROUND

Pulmonary vasodilatation with a 100 ppm concentration of NO given as a short burst of a few milliliters at the beginning of each breath (NOmin) was compared with conventionally inhaled NO, in which a full breath of 40 ppm of NO was inhaled (NOCD).

METHODS AND RESULTS

NOmin was studied in 16 patients with severe pulmonary hypertension and in 16 isolated porcine lungs with experimentally induced pulmonary hypertension. We compared volumes of 8 to 38 mL of 100 ppm NO in N2 injected at the beginning of each breath with conventional inhalation of 40 ppm NO in air. NOCD and NOmin were studied in 4 pigs after inhibition of NO synthase with NG-nitro-L-arginine methyl ester (1 to 2 mg/kg IV) had raised the pulmonary vascular resistance index (PVRI) from 4.4+/-0.8 to 10. 0+/-1.6 mm Hg. L-1. min-1. kg-1. A similar comparison was made in 7 isolated porcine lungs after the thromboxane analogue U46619 (10 pmol. L-1. min-1) increased the mean PVRI from 4.6+/-0.8 to 12.2+/-1. 3 mm Hg. L-1. min-1. kg-1. Patients' mean PVRI was reduced from 29. 2+/-3.7 to 24.0+/-3.1 with NOmin and 24.5+/-3.3 mm Hg. L-1. min-1. m-2 (mean+/-SEM) with NOCD. In isolated porcine lungs, there was the same reduction of PVRI for NOmin and NOCD between 12.7% and 34.8%.

CONCLUSIONS

A small volume of NO inhaled at the beginning of the breath was equally effective as NOCD but reduced the dose of NO per breath by 40-fold, which ranged from 1.2x10(-8) (0.4 microg) to 1. 6x10(-7) mol/L (4.8 microg) compared with 5.3x10(-7) (16 microg) to 1.2x10(-6) mol/L (36 microg) per breath with NOCD.

Treatment of pulmonary hypertension with the continuous infusion of a prostacyclin analogue, iloprost

OBJECTIVE

To compare prostacyclin with an analogue, iloprost, in treatment of severe pulmonary hypertension.

PATIENTS

Eight patients with severe pulmonary hypertension: primary in five, thromboembolic pulmonary hypertension in three.

METHODS

All patients underwent right heart catheterisation. Mean (SEM) right atrial pressure was 9.9 (2.2) mm Hg, mean pulmonary artery pressure 67.4 (3.0) mm Hg, cardiac index 1.75 (0.13) l/min/m2 and mixed venous oxygen saturation 59.1(3.1)%. Continuous intravenous epoprostenol (prostacyclin, PGI2) or iloprost was given for phase I (three to six weeks); the patients were then crossed over to receive the alternate drug in an equivalent phase II.

MAIN OUTCOME MEASURES

Exercise tolerance was measured at baseline and at the end of phase I and II with a 12 minute walk; distance covered, rest period, percentage drop in arterial oxygen saturation (delta Sao2%) and percentage rise in heart rate (delta HR%).

RESULTS

Walking distance covered rose from (mean (SEM)) 407.5 (73) to 591 (46) m with PGI2 (p = 0.004) and to 602.5 (60) m while on iloprost (p = 0.008). Rest period decreased from 192 (73) seconds at baseline to 16 (16) seconds with PGI2 (p = 0.01) and to 58 (34) seconds with iloprost (p = 0.008). Delta HR% was 37.5(6)% at baseline, 35(3)% on PGI2, and 24(6)% on iloprost (p = 0.04).

CONCLUSIONS

Both intravenous PGI2 and iloprost caused significant improvement in exercise tolerance. Iloprost offers an alternative to PGI2 treatment of severe pulmonary hypertension.

Inhaled nitric oxide and arterial oxygen tension in patients with chronic obstructive pulmonary disease and severe pulmonary hypertension

BACKGROUND

Inhaled nitric oxide (NO) is a selective pulmonary vasodilator which can improve gas exchange in acute lung injury. However, it is uncertain that this effect on arterial oxygenation can be generalised to all lung diseases.

METHODS

The effects of inhaled NO on gas exchange were studied in nine patients with chronic obstructive pulmonary disease (COPD), 11 patients with severe pulmonary hypertension, and 14 healthy volunteers. A randomized sequence of 40 ppm of NO or air was inhaled for 20 minutes through an orofacial mask.

RESULTS

Inhaled NO reduced mean (SE) transcutaneous arterial oxygen tension (TcPO2) from 9.6 (0.3) to 8.9 (0.4) kPa in healthy volunteers and from 7.4 (0.6) to 7.0 (0.5) kPa in patients with COPD. There was no change in TcPO2 in patients with severe pulmonary hypertension. During inhalation of NO and air no change occurred in transcutaneous arterial carbon dioxide tension (TcPCO2), arterial oxygen saturation (SaO2) measured by pulse oximeter, or cardiac output determined by the transthoracic impedance method.

CONCLUSIONS

Inhaled NO does not improve TcPO2 nor increase cardiac output in normal subjects and patients with COPD, suggesting that inhaled NO worsens gas exchange. This could represent inhaled NO overriding hypoxic pulmonary vasoconstriction in COPD. The finding that TcPO2 also fell when normal subjects inhaled NO suggests that a similar mechanism normally contributes to optimal gas exchange. Whilst inhaled NO can improve oxygenation, this effect should not be considered to be a general response but is dependent on the type of lung disease.

Nature and site of action of endogenous nitric oxide in vasculature of isolated pig lungs

The site of action of endogenous and exogenous nitric oxide (NO) in isolated pig lungs was investigated by using arterial, double, and venous occlusions, which allowed precapillary, postcapillary, and venous segments to be partitioned into arterial, precapillary, postcapillary, and venous segments. NG-nitro-L-arginine (L-NNA; 10(-5) M) increased resistance in the arterial (35 +/- 6.6%. P = 0.003), precapillary (39.3 +/- 5.1%, P = 0.001), and venous (18.3 +/- 4.8%, P = 0.01) segments, respectively. Sodium nitroprusside (10(-5) M) NO (80 parts/million) reversed the effects of L-NNA. Total pulmonary vascular resistance fell with increasing flow, due to a fall in precapillary resistance and dynamic resistance, and was significantly lower than mean total resistance. L-NNA increased the resistances but did not alter the pattern of the pressure-flow relationships. It is concluded that, in isolated pig lungs, the effect of endogenous NO seems to be dependent on flow in the arterial segment and independent of flow in the precapillary segment, but variation of its release does not appear to be fundamental to accommodation to changes in steady flow.

Elevated exhaled nitric oxide in patients with hepatopulmonary syndrome

The hypoxaemia of hepatopulmonary syndrome, seen in severe chronic liver dysfunction, occurs as a result of precapillary pulmonary arterial dilatation and arteriovenous communications. These abnormalities contribute to the mismatch between ventilation and perfusion, and the right to left blood flow shunting. Nitric oxide (NO) is a powerful vasodilator concerned with the regulation of pulmonary vascular tone in man. Using a chemiluminescence analyser, we have measured endogenously produced NO in the exhaled air of three patients with the hepatopulmonary syndrome, six normoxaemic cirrhotic patients and six healthy volunteers. The subjects breathed NO-free air throughout the measurements. The molar rate of production of exhaled NO was raised almost threefold in the patients with hepatopulmonary syndrome compared with normal volunteers and with normoxaemic cirrhotic patients. Hypoxia per se, achieved in the normal volunteers by breathing a hypoxic gas mixture, reduced rather than increased the exhaled NO. One hepatopulmonary syndrome patient received an orthotopic liver transplant and achieved normoxaemia after 3 months. The exhaled NO also returned to normal. Increased pulmonary production of NO could contribute to the development of the hepatopulmonary syndrome.

Role of prostacyclin in the treatment of primary pulmonary hypertension

Over the last decade, new medical and surgical treatments have become available for primary pulmonary hypertension that have influenced the natural history of the disease. Vasodilator therapy is aimed at overcoming pulmonary vasoconstriction with consequent decrease in afterload and improved right ventricular output. The endpoint of vasodilator therapy is therefore to reduce pulmonary vascular resistance, without causing significant systemic hypotension. Prostacyclin, a potent vasodilator and antiaggregating agent, has been successfully used by continuous infusion in the treatment of severe pulmonary hypertension. The marked improvement in quality of life observed with the use of prostacyclin in these patients, as well as the increased survival time on the waiting list for transplantation, has influenced us to adopt prostacyclin infusion as a fundamental element of our therapeutic strategy for the management of this rare but fatal condition.

Exhaled nitric oxide in isolated pig lungs

Endothelium-derived nitric oxide (NO) is an important regulator of vascular resistance. Low concentrations of NO have been recorded in the exhaled breath of spontaneously breathing animals and humans. To determine whether NO synthesis in the lung contributes to the NO measured in the breath, we measured the concentration of NO in the exhaled air of isolated perfused and ventilated porcine lungs by using a chemiluminescence method. With NO-free normoxic ventilation (21% O2-5% CO2-74% N2) of eight porcine lungs perfused with a Krebs-dextran and albumin perfusate, baseline exhaled NO was 5.8 +/- 1.8 parts per billion (ppb) and pulmonary vascular resistance (PVR) was 8.9 +/- 1.8 mmHg.l-1.min. Hypoxic ventilation (5% O2-5% CO2-90% N2) caused a fall in NO to 3.6 +/- 1.8 ppb and a rise in PVR to 13.6 +/- 3.6 mmHg.l-1.min. Vasoconstriction with the thromboxane analogue U-46619 (10(-9) M) raised PVR to 31.7 +/- 6.8 mmHg.l-1.min but did not decrease NO levels from baseline. Subsequent addition of acetylcholine (10(-6)M) lowered PVR to 22.1 +/- 4.5 mmHg.l-1.min and increased exhaled NO to 7.0 +/- 2.0 ppb. Addition of a NO synthase inhibitor, NG-nitro-L-arginine methyl ester (10(-5) M), to four lungs caused a rise in PVR to 43.0 +/- 7.0 mmHg.l-1.min and a decrease in NO to 1.5 +/- 1.0 ppb. Addition of autologous blood to the perfusate of four lungs caused no change in PVR from baseline but decreased exhaled NO to 2.7 +/- 0.5 ppb.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of inhibitors of nitric oxide release and action on vascular tone in isolated lungs of pig, sheep, dog and man

1. The actions of inhibitors of the release or action of nitric oxide (NO) on pulmonary vascular resistance (PVR) were investigated in lungs isolated from pig, sheep, dog and man. 2. In pig, sheep and human lungs perfused with Krebs-dextran solution, both N omega-nitro-L-arginine methyl ester (L-NAME; 10(-5) M) and Methylene Blue (10(-4) M) increased basal PVR. This increase was reversed by sodium nitroprusside (10(-5) M). In pig lungs N omega-monomethyl-L-arginine (10(-4) M) increased PVR by 154%. This increase was partially reversed by L-arginine (10(-3) M). L-NAME had no effect in dog lungs. 3. Pulmonary artery pressure-flow (PPA/Q) relationships were studied over a wide range of flows. In pigs, sheep and human lungs perfused with Krebs-dextran solution, L-NAME increased the PPA/Q slope. This increase was reversed by sodium nitroprusside. In dog lungs L-NAME had no effect. 4. In blood-perfused lungs, the respective responses to L-NAME were similar to those observed with saline. Acute hypoxia in pig and dog lungs increased intercept pressure. Addition of L-NAME during hypoxia increased the PPA/Q slope in both species. 5. In the human, there was no difference in the absolute increase of PVR or PPA/Q slope elicited by L-NAME between hypertensive and control lungs. 6. We conclude that NO is continuously released in the pulmonary vascular bed of pig, sheep and humans under normoxic conditions. In dog lungs inhibition of NO synthesis increases PVR only under hypoxic conditions. In human lungs with pulmonary hypertension, NO is still released under basal conditions.

Mixed expired nitric oxide in primary pulmonary hypertension in relation to lung diffusion capacity

The mixed expired nitric oxide (NO) production of the lungs of patients with primary pulmonary hypertension (PPH) and normal subjects was measured to determine the relationship between NO production and the diffusion capacity of the lung (KCO). Expired air was collected from eight patients with PPH and 20 healthy volunteers for analysis by a chemiluminescent analyser. Mean pulmonary artery pressure in the PPH patients was 59.5 +/- 6.45 mmHg and their mean cardiac output was 2.95 +/- 0.35 l/min. All patients and subjects underwent measurements of FEV1, VC and KCO. The rate of production of NO in mixed exhaled air was lower in the PPH group compared to the controls (2.85 +/- 0.7 vs. 4.69 +/- 0.35 nM/min; p < 0.05). There was a good correlation of expired NO with the KCO (r = 0.7; n = 30; p < 0.001). When corrected, KCO differences in exhaled NO were not significant (p = 0.09). We conclude that the low exhaled NO observed in PPH patients is a reflection of the reduced blood capillary volume in these patients rather than a decreased basal production of NO.

The role of prostacyclin in the treatment of primary pulmonary hypertension: the Cambridge experience

Over the last decade new medical and surgical treatments have become available for primary pulmonary hypertension which have influenced the natural history of the disease. Vasodilator therapy is aimed at overcoming pulmonary vasoconstriction with consequent decrease in afterload and improved right ventricular output. The endpoint of vasodilator therapy is therefore to reduce pulmonary vascular resistance, without causing significant systemic hypotension. Prostacyclin, a potent vasodilator and antiaggregating agent, has been successfully used by continuous infusion in the treatment of severe pulmonary hypertension. The marked improvement in quality of life observed with the use of prostacyclin in these patients as well as the increased survival time on the waiting list for transplantation has influenced us to adopt PGI2 infusion as a fundamental element of our therapeutic strategy for the management of this rare but fatal condition.

Acute and chronic hypoxic pulmonary hypertension

The development of secondary pulmonary hypertension (PH) as a result of pulmonary disease, both in adults and children, considerably worsens prognosis. Chronic hypoxia appears to be the cause, as long-term oxygen therapy (LTOT) reverses or at least impedes the progressive development of PH. There is now clear evidence that acute hypoxia causes smooth muscle contraction in pulmonary arteries through a direct effect on intracellular calcium levels. Subsequent relaxation depends upon activation of ion transport mechanisms which can be modified by circulating hormones such as the naturally occurring ouabain. Sustained hypoxia can cause adaptation of pulmonary endothelium. One change is a reduction in nitric oxide (NO) production, possibly through reduced activity of the formative enzyme nitric oxide synthase. Basal production of NO appears important in many species including man in determining the low pulmonary vascular resistance. Impaired endothelial NO production as a result of sustained hypoxia may well enhance the development of secondary PH. Much attention is now focused on the regulation of nitric oxide synthase, both the constitutive form in endothelium as well as the inducible form of inflammatory cells. It is possible that either gene transcription or translation are modified when endothelial cells are exposed to chronic hypoxia. This allows the opportunity for therapeutic intervention. More needs to be learnt about the cellular and molecular adaptation to hypoxia in man but novel approaches to treatment may soon arrive for patients with chronic obstructive lung disease and secondary pulmonary hypertension.

Impairment of pulmonary-artery endothelium-dependent relaxation in chronic obstructive lung disease is not due to dysfunction of endothelial cell membrane receptors nor to L-arginine deficiency

1. Endothelium-dependent relaxation mediated by endothelium-derived relaxing factor (EDRF) or nitric oxide (NO), is impaired in pulmonary arteries (PA) of hypoxic patients with chronic obstructive lung disease (COLD). To determine the mechanisms responsible for this impairment, we compared the response of rings of isolated PA from 12 COLD patients and 8 controls to the endothelium-dependent vasodilators acetylcholine (ACh), adenosine diphosphate (ADP), and the calcium ionophore, A23187. The response of PA rings to the endothelium-independent nitro-vasodilator sodium nitroprusside (SNP) was also studied in both groups. The PA rings had been pre-contracted by the alpha-adrenoceptor agonist phenylephrine (PE). 2. Endothelium-dependent relaxation was significantly reduced in PA rings from COLD patients as compared with controls when tested with ACh (37.8 +/- 8.8% vs 73.4 +/- 7.9%), ADP (38.4 +/- 6.7% vs 80 +/- 5.6%), and the calcium ionophore, A23187 (35.8 +/- 6.1% vs 87 +/- 6.6%). Relaxation with SNP was, however, significantly greater in PA rings from COLD patients (99.4 +/- 0.6% vs 90.3 +/- 3.1%), as was the contractile response to PE (1.91 +/- 0.21 g vs 1.33 +/- 0.15 g). Pretreatment with the specific inhibitor of NO formation, NG-monomethyl-L-arginine (L-NMMA; 10(-4) M) significantly reduced the relaxation to ACh in all PA rings. This inhibition could be reversed by L-arginine (10(-3) M), the substrate for NO synthesis. Pretreatment with L-arginine alone, however, did not restore the impaired endothelium-dependent relaxation of PA rings from COLD patients. 3. We conclude that EDRF (NO) production is impaired in PA rings from COLD patients and that this impairment is neither due to endothelial receptors dysfunction nor a defect of L-arginine availability and/or transport. Our hypothesis is that the abnormality must lie within the biosynthesis pathway of NO from L-arginine, possibly involving the endothelial enzyme cell, NO synthase, the normal function of which might be altered by chronic hypoxia.

In vitro pulmonary vasorelaxant effect of the phosphodiesterase inhibitor enoximone

Enoximone is a phosphodiesterase inhibitor that has both positive inotropic and systemic vasorelaxant activities. The latter are mediated by an increase in vascular smooth muscle concentration of cyclic 3'5' guanosine monophosphate. However, the effect of enoximone on pulmonary vasoreactivity is not established. The authors, therefore, have studied its effect on endothelium-dependent relaxation mediated by the endothelium-derived relaxing factor nitric oxide (NO), as well as endothelium-independent relaxation of isolated porcine pulmonary arteries. Enoximone (10(-7) to 10(-4) M) caused a dose-dependent relaxation in all pulmonary arterial rings. This relaxation neither required the presence of the endothelium nor was affected by the addition of the inhibitor of NO synthase omega-nitro-L-arginine methyl ester (10(-4) M). Also, the vasorelaxant response of the rings to the endothelium-dependent vasodilator adenosine diphosphate (10(-10) to 10(-5) M) was not affected by pretreatment with enoximone. The authors conclude that enoximone is a potent vasodilator that relaxes pulmonary vascular rings through mechanisms independent of the endothelium. This endothelium-independent vasodilatory effect of enoximone makes it a potentially valuable drug for the treatment of pulmonary hypertension. This particularly applies to diseases in man where NO production by the endothelial cells is impaired.

Influence of serum proteins on fructosamine concentration in multiple myeloma

Serum fructosamine levels in 36 subjects with various types of multiple myeloma and in 64 normal controls were evaluated by means of a Nitroblue tetrazolium colorimetric assay. Only the IgA myeloma group showed significantly raised serum fructosamine values (P less than 0.001). In the IgG myeloma group, which showed a higher mean serum protein concentration, serum fructosamine levels were not significantly different from controls. The study shows that elevated IgA levels do influence serum fructosamine and this effect should be taken into due consideration in order to avoid possible misinterpretations in evaluating this widely used index of glucose metabolism.

Endothelium-derived relaxing factor and the pulmonary circulation

Endothelium-derived relaxing factor (EDRF) is probably identical to nitric oxide (NO) and is released by the vascular endothelium both in the basal unstimulated state and in response to a wide range of physical and chemical stimuli. Since it was first described 10 years ago, evidence is accumulating that it is an important modulator of vascular smooth muscle tone. EDRF acts on the pulmonary vascular bed as on the systemic circulation. EDRF release to pharmacologic stimuli is impaired in pulmonary arteries from patients with chronic hypoxemia. This impairment is associated with severity of respiratory failure and of structural change of vessel walls. Disturbance of EDRF activity may be important in the pathophysiology of pulmonary vascular disease. This brief review describes the current status of experimental studies concerning the possible role of EDRF on the pulmonary circulation in normal conditions and in the pathogenesis of pulmonary hypertension.

[Is there a typical radiologic picture of primary pulmonary hypertension? Study of 18 cases]

The conventional chest radiographs were studied of 18 patients with primary pulmonary hypertension, waiting for, or treated with lung transplantation in the Papworth Hospital. The goal of the study was to find out whether there is a pattern characteristic of primary pulmonary hypertension. The following points were considered: a) pulmonary transparency; b) the hila; c) the left hemidiaphragm; d) the pulmonary artery; e) the right ventricle; f) the right atrium; g) the left ventricle. A score was assigned for any degree of abnormality of the points mentioned above. As a result, a radiological pattern was found that can: 1) confirm the presence of pulmonary hypertension; 2) exclude that this hypertension has a detectable cause; 3) measure the severity of the disease, particularly with regard to hypertension degree. The conclusion is that there is a radiological pattern strongly suggestive of primary pulmonary hypertension and that conventional radiology can help in detecting and monitoring this rare disease, which today can only be treated by means of transplantation.

The alpha 1-adrenergic agonist methoxamine and the "loop" diuretic frusemide reduce nasal potential difference

Pretreatment by inhalation with the alpha 1-adrenergic agonist methoxamine and the "loop" diuretic frusemide reduces the bronchial response to certain airway challenges in asthma. To test whether these drugs may act by altering airway epithelial ion and water transport, their effect on nasal potential difference (PD) when applied topically in eight normal volunteers was measured. For comparison, the effect of the Na(+)-channel blocking drug amiloride and the beta 2-adrenergic agonist salbutamol was also tested. Both methoxamine and frusemide significantly reduced PD: at the highest concentration given (10(-3) mol.l-1), there was a mean drop in PD from baseline of 39.5% following methoxamine treatment (p less than 0.05) and a mean drop of 30.2% following frusemide (p less than 0.05). Neither drug was as effective as amiloride, which caused a mean drop in PD of 27.5% from baseline at 10(-6) mol.l-1 and a drop of 71.6% at 10(-3) mol.l-1 (p less than 0.01 for each concentration). Salbutamol had no significant effect on PD (p greater than 0.05). We conclude that methoxamine and frusemide may derive their protective effect on some bronchial challenge, at least in part, from their effect on airway epithelial ion flux.

The alpha 1-adrenergic agonist methoxamine and the "loop" diuretic frusemide reduce nasal potential difference

Pretreatment by inhalation with the alpha 1-adrenergic agonist methoxamine and the "loop" diuretic frusemide reduces the bronchial response to certain airway challenges in asthma. To test whether these drugs may act by altering airway epithelial ion and water transport, their effect on nasal potential difference (PD) when applied topically in eight normal volunteers was measured. For comparison, the effect of the Na(+)-channel blocking drug amiloride and the beta 2-adrenergic agonist salbutamol was also tested. Both methoxamine and frusemide significantly reduced PD: at the highest concentration given (10(-3) mol.l-1), there was a mean drop in PD from baseline of 39.5% following methoxamine treatment (p less than 0.05) and a mean drop of 30.2% following frusemide (p less than 0.05). Neither drug was as effective as amiloride, which caused a mean drop in PD of 27.5% from baseline at 10(-6) mol.l-1 and a drop of 71.6% at 10(-3) mol.l-1 (p less than 0.01 for each concentration). Salbutamol had no significant effect on PD (p greater than 0.05). We conclude that methoxamine and frusemide may derive their protective effect on some bronchial challenge, at least in part, from their effect on airway epithelial ion flux.

Impairment of endothelium-dependent pulmonary-artery relaxation in chronic obstructive lung disease

BACKGROUND

Endothelial cells release endothelium-derived relaxing factor (EDRF) in a variety of vascular beds, including the pulmonary circulation. However, the role of EDRF-mediated pulmonary-artery relaxation in chronic hypoxic lung disease is unknown.

METHODS

We studied endothelium-dependent relaxation mediated by EDRF in vitro in pulmonary arteries that had been obtained from 22 patients undergoing heart-lung transplantation for end-stage chronic obstructive lung disease. Control pulmonary arteries were obtained from 15 patients undergoing lobectomy for lung carcinoma who did not have evidence of other chronic lung disease. The responses of all vascular rings (external diameter, 1.2 to 3.4 mm) to the endothelium-dependent vasodilators acetylcholine and adenosine diphosphate were studied immediately after lung excision.

RESULTS

Pulmonary arterial rings from the patients with chronic lung disease developed a greater tension (2.19 +/- 0.16 g) in response to phenylephrine (10(-6) M) than the rings from control patients (1.28 +/- 0.18 g, P less than 0.05). Inhibition of EDRF synthesis by treatment with NG-monomethyl-L-arginine (10(-4) M) eliminated this difference, increasing the tension in the rings from the controls (P less than 0.01) but not in those from the patients with chronic lung disease. Rings from control patients relaxed in response to cumulative doses (10(-10) to 10(-5) M) of acetylcholine (maximal relaxation, 81.3 +/- 3.9 percent) and adenosine diphosphate (maximal relaxation, 85.3 +/- 2.6 percent). By contrast, rings from patients with chronic obstructive lung disease achieved only 41.3 +/- 4.8 percent of maximal relaxation in response to acetylcholine (n = 32) and 49.4 +/- 5.5 percent in response to adenosine diphosphate (n = 24) (P less than 0.001, as compared with control rings). Rings from both the controls and the patients with chronic lung disease relaxed similarly in response to the endothelium-independent vasodilator sodium nitroprusside (10(-4) M). There was an inverse correlation between the degree of intimal thickening and the level of maximal relaxation of the rings from the patients with chronic lung disease (r = -0.60, P less than 0.001). Maximal relaxation was also related directly to the partial pressure of arterial oxygen before transplantation (r = 0.68, P less than 0.01) and inversely to the partial pressure of arterial carbon dioxide before transplantation (r = -0.55, P less than 0.01), but not to the forced expiratory volume in one second (r = 0.19, P not significant).

CONCLUSIONS

Endothelium-dependent pulmonary-artery relaxation in vitro is impaired in arteries from patients with end-stage chronic obstructive lung disease. Such impairment may contribute to the development of pulmonary hypertension in chronic hypoxic lung disease.

Transplantation for end-stage lung disease

The last decade has seen lung and heart-lung transplantation move from experimental procedures to clinical treatments. Innovative surgical techniques combined with the use of ciclosporin as an immunosuppressive agent have enabled successful transplantation in a wide range of end-stage lung diseases. Exclusion criteria for selecting recipients have relaxed, and improved preservation techniques have facilitated distant donor organ procurement and decreased peri-operative mortality. A range of techniques for the physiological monitoring of the graft as well as diagnosis of major complications such as rejection and opportunistic infection have been introduced. Obliterative bronchiolitis remains a major challenge to the immunologist and to the chest physician in terms of etiology, pathogenesis and treatment. As survival rates improve with improved management, lung and heart-lung transplantations are contributing towards effective treatment of end-stage pulmonary disease as well as providing new insight into pulmonary physiology and into mechanisms of lung disease.

Impairment of pulmonary endothelium-dependent relaxation in patients with Eisenmenger's syndrome

A comparison has been made between the endothelium-dependent relaxation of pulmonary arteries (PA) obtained at heart-lung transplantation from 4 patients with Eisenmenger's syndrome and secondary pulmonary hypertension, and PA obtained at lobectomy from 4 patients with lung carcinoma, the controls. All vascular rings were studied immediately after lung excision. PA rings from control patients dose-dependently relaxed to cumulative doses of acetylcholine (ACh, 10(-10) to 10(-5) M), achieving a maximal relaxation of 80 +/- 5% (mean +/- s.e. mean) from precontraction with phenylephrine. By contrast, PA rings from Eisenmenger's syndrome patients achieved a maximal relaxation of only 34 +/- 12% (P less than 0.05, unpaired t test), with even paradoxical contraction at high doses of ACh (10(-6) to 10(-5) M). Sodium nitroprusside (10(-4) M) relaxed all PA rings, with and without endothelium (carefully removed before study), obtained from both control and Eisenmenger's syndrome patients. These results provide the first evidence that endothelium-dependent relaxation of PA mediated by endothelium-derived relaxing factors is impaired in Eisenmenger's syndrome patients with secondary pulmonary hypertension.

Twenty-four-hour blood pressure monitoring after a single dose of sustained-release verapamil

The antihypertensive effect of a single dose of 240 mg sustained-release (S-R) verapamil was investigated by ambulatory blood pressure (BP) monitoring in 13 patients with mild to moderate essential hypertension. Following a 2-week washout period, 24-hour BP monitoring was carried out with a Spacelabs ICR 5300 device following random administration of a tablet of S-R verapamil or placebo; BP recording was repeated after crossover 3 to 7 days later. Average whole-day systolic and diastolic BPs were significantly lower after verapamil (130.1 +/- 2.6/87.1 +/- 1.2 mmHg) than after placebo (142.1 +/- 3.3/95.8 +/- 2.1 mmHg) (p less than 0.01). Mean waking BP was 146.4 +/- 3.6/99.1 +/- 2.2 mmHg after placebo and 135.2 +/- 3.3/90.5 +/- 1.7 mmHg after verapamil (p less than 0.01); during sleeping hours BP was 133.8 +/- 3.1/88.7 +/- 2.6 mmHg following placebo and 122.2 +/- 2.3/80.9 +/- 1.8 mmHg following verapamil (p less than 0.01). Blood pressure profile was significantly reduced by verapamil up to 20 hours after tablet administration, while from 21 to 24 hours after drug intake BP values were similar to placebo. Response to verapamil was not correlated to the pretreatment BP values and to the patient's age. In summary, this study suggests that acute administration of 240 mg S-R verapamil in hypertensive patients produces a BP reduction during 24-hour, daytime, and nighttime periods. The hypotensive efficacy is preserved for many hours after tablet intake and seems to be due to individual variation in cardiovascular reactivity to the drug.