Lucia Spicuzza

Modulatory effects of respiration

Respiration is a powerful modulator of heart rate variability, and of baro- and chemoreflex sensitivity. Abnormal respiratory modulation of heart rate is often an early sign of autonomic dysfunction in a number of diseases. In addition, increase in venous return due to respiration may help in maintaining blood pressure during standing in critical situations. This review examines the possibility that manipulation of breathing pattern may provide beneficial effects in terms not only of ventilatory efficiency, but also of cardiovascular and respiratory control in physiologic and pathologic conditions, such as chronic heart failure. This opens a new area of future research in the better management of patients with cardiovascular autonomic dysfunction.

Slow breathing reduces chemoreflex response to hypoxia and hypercapnia, and increases baroreflex sensitivity.

Objective To investigate whether breathing more slowly modifies the sensitivity of the chemoreflex and baroreflex. Design Setting University of Pavia, IRCCS Policlinico S. Matteo. Participants: Fifteen healthy individuals. Interventions: Progressive isocapnic hypoxia and progressive hyperoxic hypercapnia were measured during spontaneous breathing and during a breathing rate fixed at 6 and 15 breaths per minute (b.p.m.). Main outcome measures: Variations in chemo- and baroreflex sensitivity (by monitoring ventilation, oxygen saturation, end-tidal carbon dioxide, R–R interval and blood pressure) induced by different breathing rates. Results Breathing at 6 b.p.m. depressed (P < 0.01) both hypoxic and hypercapnic chemoreflex responses, compared with spontaneous or 15 b.p.m. controlled breathing. Hypoxic and hypercapnic responses during spontaneous breathing correlated with baseline spontaneous breathing rate (r = −0.52 and r = +0.51, respectively;P = 0.05). Baroreflex sensitivity was greater (P < 0.05) during slow breathing at baseline and remained greater at end rebreathing. Conclusions Slow breathing reduces the chemoreflex response to both hypoxia and hypercapnia. Enhanced baroreflex sensitivity might be one factor inhibiting the chemoreflex during slow breathing. A slowing breathing rate may be of benefit in conditions such as chronic heart failure that are associated with inappropriate chemoreflex activation.

Yoga and chemoreflex response to hypoxia and hypercapnia

We tested whether chemoreflex sensitivity could be affected by the practice of yoga, and whether this is specifically because of a slow breathing rate obtained during yoga or as a general consequence of yoga. We found that slow breathing rate per se substantially reduced chemoreflex sensitivity, but long-term yoga practice was responsible for a generalised reduction in chemoreflex.

Research applications and implications of adenosine in diseased airways

Adenosine, when given by inhalation, initiates the narrowing of airways in subjects with asthma or chronic obstructive pulmonary disease (COPD). The underlying mechanism of this narrowing appears to involve the stimulation of specific mast cell surface adenosine receptors with the subsequent release of mediators and contraction of airway smooth muscle. Although methacholine and histamine have become gold standards as bronchial provocants used to quantify bronchial hyperresponsiveness, the airways response to the indirect stimulus adenosine more closely reflects bronchial inflammation. This distinctive feature of adenosine could be exploited to enable superior diagnostic discrimination between asthma and COPD, allow better monitoring of disease activity and progression, and improve the individual adjustment of long-term asthma management with topical glucocorticosteroids. In this article, we review recent developments in this area of rapidly evolving clinical research, focusing on the putative role of adenosine as a mediator of airway inflammation and as a useful bronchoprovocant in several clinical and research applications.

Emerging pathogens in cystic fibrosis: ten years of follow-up in a cohort of patients

In patients with cystic fibrosis (CF), there is an increasing incidence of some uncommon respiratory pathogens, such as Burkholderia cepacia complex (Bcc), Stenotrophomonas maltophilia, and Achromobacter xylosoxidans. In order to evaluate the prevalence and the clinical impact of these pathogens, we retrospectively studied a total of 109 patients followed in our center from 1996 to 2006 and reviewed the results of 1,550 sputum samples. The isolation of Pseudomonas aeruginosa slightly decreased over the observed decade, whereas Staphylococcus aureus exhibited an irregular trend. Infection with Bcc reached a peak in 1998 and successively decreased to a stable 4%. S. maltophilia and A. xylosoxidans were the real emerging pathogens, since first isolation occurred in 2004; however, the percentage of infected patients remained low (7% and 3.2%, respectively) through the years. In conclusion, in our center for CF, the reduced prevalence of P. aeruginosa over the last decade has been associated with a concurrent reduction of infections by Bcc and, as compared to other centers in Italy, Europe, and the US, with a low incidence of emerging pathogens such as S. maltophilia and A. xylosoxidans.

Early treatment with noninvasive positive pressure ventilation prolongs survival in Amyotrophic Lateral Sclerosis patients with nocturnal respiratory insufficiency

BackgroundAmyotrophic lateral sclerosis (ALS) is a neurodegenerative disease, which rapidly leads to chronic respiratory failure requiring mechanical ventilation. Currently, forced vital capacity (FVC) < 50% is considered as physiologic marker for admitting patients to Noninvasive Positive Pressure Ventilation (NPPV) intervention, although it has been recently shown the median survival of patients with baseline FVC < 75% much shorter than median survival of patients with baseline FVC > 75%, independently by any treatment.AimTo assess the role of NPPV in improving outcome of ALS, a retrospective analysis was performed to investigate 1 year survival of ALS patients with FVC < 75% and nocturnal respiratory insufficiency, treated with NPPV, compared to a well-matched population of ALS patients, who refused or was intolerant to NPPV.MethodsWe investigated seventy-two consecutive ALS patients who underwent pulmonary function test. Forty-four presented a FVC > 75% and served as control group. Twenty-eight patients presented a FVC < 75% and showed, at polysomnography analysis, nocturnal respiratory insufficiency, requiring NPPV; sixteen were treated with NPPV, while twelve refused or were intolerant.ResultsIncreased survival rate at 1 year in patients with FVC < 75% treated with NPPV, as compared to those who refused or could not tolerate NPPV (p = 0.02), was observed. The median rate of decline in FVC% was slower in NPPV patients than in patients who did not use NPPV (95% CI: 0.72 to 1.85; p < 0.0001).ConclusionThis report demonstrates that early treatment with NPPV prolongs survival and reduces decline of FVC% in ALS.

Hepatitis B vaccination failure in celiac disease: is there a need to reassess current immunization strategies?

Human leukocyte antigen (HLA) phenotype DQ2 is considered the most important genetic marker for un-responsiveness to hepatitis B vaccine. Since celiac disease (CD) is also strongly associated with the same haplo-type it may be hypothesized that celiac patients are less able to respond to the vaccine. We report a retrospective study on celiac patients vaccinated with three doses of 10 microg at 3, 5 and 11 months of age by an intramuscular injection of a recombinant hepatitis B vaccine (Engerix B). We found 30 of 60 celiac patients (50%) unresponsive to vaccination and a significant higher number of responders among patients younger than 18 months at the time of celiac disease diagnosis. Our study confirms that celiac patients have a lower percentage of response to hepatitis B vaccination than healthy subjects. These findings provide useful information to evaluate if current vaccine strategies should be reassessed and if revaccination should be recommended.

Sleep-related hypoxaemia and excessive erythrocytosis in Andean high-altitude natives

To determine whether nocturnal hypoxaemia contributes to the excessive erythrocytosis (EE) in Andean natives, standard polysomnographies were performed in 10 patients with EE and in 10 controls (mean haematocrit 76.6±1.3% and 54.4±0.8%, respectively) living at an altitude of 4,380 m. In addition, the effect of O2 administration for 1 h prior to sleep, and the relationship between the hypoxic/hypercapnic ventilatory response and the apnoea/hypopnoea index (AHI) during sleep were studied. Awake arterial oxygen saturation (Sa,O2) was significantly lower in patients with EEthan in controls (83.7±0.3% versus 85.6±0.4%). In both groups, the mean Sa,O2 significantly decreased during sleep (to 80.0±0.8% in EE and to 82.8±0.5% in controls). The mean Sa,O2 values remained significantly lower in patients with EE than in controls at all times of the night, and patients with EE spent significantly more time than the controls with an Sa,O2 of <80%. There were no differences between the two groups in the number and duration of the apnoeas/hypopnoeas. None of these variables were affected by O2 administration. In both groups the AHI positively correlated with the hypercapnic ventilatory response. Andean natives undergo minor respiratory disorders during sleep. The reduction inoxygen saturation found in subjects with excessive erythrocytosis was small, yet consistent and potentially important, as it remained below the threshold known for theincrease in erythropoietin stimulation. This may be an important factor promoting erythropoiesis, but its relevance needs to be further explored.

Obstructive sleep apnoea syndrome and its management

Obstructive sleep apnoea (OSA) is a common disorder characterized by repetitive episodes of nocturnal breathing cessation due to upper airway collapse. OSA causes severe symptoms, such as excessive daytime somnolence, and is associated with a significant cardiovascular morbidity and mortality. Different treatment options are now available for an effective management of this disease. After more than three decades from its first use, continuous positive airway pressure (CPAP) is still recognized as the gold standard treatment. Nasal CPAP (nCPAP) is highly effective in controlling symptoms, improving quality of life and reducing the clinical sequelae of sleep apnoea. Other positive airway pressure modalities are available for patients intolerant to CPAP or requiring high levels of positive pressure. Mandibular advancement devices, particularly if custom made, are effective in mild to moderate OSA and provide a viable alternative for patients intolerant to CPAP therapy. The role of surgery remains controversial. Uvulopalatopharyngoplasty is a well established procedure and can be considered when treatment with CPAP has failed, whereas maxillar-mandibular surgery can be suggested to patients with a craniofacial malformation. A number of minimally invasive procedures to treat snoring are currently under evaluation. Weight loss improves symptoms and morbidity in all patients with obesity and bariatric surgery is an option in severe obesity. A multidisciplinary approach is necessary for an accurate management of the disease.

Role of endogenous nitric oxide in asthma

Endogenous nitric oxide (NO) is an ubiquitous signaling molecule with important regulatory functions such as regulation of blood pressure, neurotransmission, and host and immune defense. In the respiratory tract, NO is formed and released by various sources including endothelial and epithelial cells, nerves, airway smooth muscle, and inflammatory cells. Recent evidence suggests that endogenous NO is the neurotransmitter of the nonadrenergic noncholinergic inhibitory (iNANC) system, the only bronchorelaxant neural pathway of human airways. A number of studies also suggest that in some species epithelium‐derived NO accounts for the functional bronchoprotective role of the so‐called epithelium‐derived relaxing factor. In human airways, endogenous NO counteracts the bronchoconstriction induced by pharmacologic stimuli such as bradykinin, histamine, and methacholine. On the basis of these and other observations, it is suggested that a reduced synthesis and/or activity of endogenous NO may contribute to the pathogenesis of airway hyperresponsiveness that characterizes asthma and other respiratory disorders. This short paper summarizes the activities of endogenous NO in the airways of experimental animals and man, and discusses the evidence supporting the view that NO confers bronchoprotection.