Chronic cough: a multidisciplinary approach.

BACKGROUND AND METHODS: Chronic cough is defined as a cough persisting for more than eight weeks. This condition generates significant healthcare and economic costs. It is associated with a spectrum of disorders across multiple medical specialties and can provide significant challenges for effective evaluation and management. The current literature was reviewed to gain further insight into chronic cough, including its relationship with sinonasal disease. RESULTS: Within the reviewed literature, there was strong emphasis on post-nasal drip syndrome as a major causative factor. CONCLUSION: Cough is the most common complaint for which adult patients seek medical consultation in primary care settings. Chronic cough is associated with a deterioration in the quality of patients' lives. Thorough assessment of a patient with a chronic cough relies on a multidisciplinary approach.

Acoustic parameters of snoring sound to compare natural snores with snores during 'steady-state' propofol sedation.

OBJECTIVES: To investigate the acoustic similarity between natural and sedation-induced snores. DESIGN: Prospective observational study. SETTING: University Hospital Aintree, Liverpool, UK. PARTICIPANTS: Twenty-one patients, who had already had overnight snore recordings, completed a pre-operative sleep nasendoscopic examination. Endoscopic examination of the upper aero-digestive tract was performed at sequentially increasing, steady-state sedation levels, using intravenous propofol administered according to a weight/time-based algorithm to predict blood and effect site (tissue) concentrations. At each sedation level at which snoring occurred, snoring sound was recorded. From these samples, snore files, comprising the inspiratory sound of each snore were created. Similarly, from natural snores recorded pre-operatively, snore files, comprising the inspiratory sounds of the first 100 snores with the patient sleeping in a supine position, were also created. MAIN OUTCOME MEASURES: Snore duration (s), loudness (dBA), periodicity (%) and energy ratios for the frequency sub-bands 0-200, 0-250 and 0-400 Hz. RESULTS: Snore loudness increased significantly (P < 0.0001), whilst energy ratios for frequency bands 0-200, 0-250 and 0-400 Hz all decreased significantly as sedation level increased (P < 0.001). A significant difference between natural snoring and snoring induced at the lowest sedation level was shown (P < 0.0001). Endoscopic examination was not tolerated at this sedation level. CONCLUSIONS: The acoustic characteristics of sedation-induced and natural snores are sufficiently different to recommend the need for further research to determine whether the technique of sleep nasendoscopy is, in fact, a valid predictor of outcome of snoring surgery.

Snoring surgery: a retrospective review.

OBJECTIVE: To undertake a retrospective, questionnaire review of surgery for heavy snoring, to ascertain patients' perception of the procedure and its effect on their snoring. PATIENTS AND METHODS: A specifically designed postal questionnaire was sent to 261 patients who underwent snoring surgery at University Hospital Aintree, Liverpool, UK, between April 1993 and March 2000. One hundred ninety-three patients responded (73.9%), including 151 men and 42 women. Mean age was 49.0 years (range, 24-74 yrs). RESULTS: Twenty-two patients had a uvulopalatopharyngoplasty, 53 a traditional laser palatoplasty and uvulectomy, and 118 an uvulopalatal elevation palatoplasty. There was a 26% patient-reported postoperative infection rate. Morbidity regarding postoperative swallowing, pharyngeal sensation or voice change appeared minimal. Seventy-six percent scored postoperative pain as "moderate" or "severe," irrespective of the operation performed (P = 0.989). Thirty-seven percent of patients perceived an improvement in postoperative sleep quality. Twenty-four percent of patients reported no improvement in snoring after surgery. Forty-three percent reported an initial improvement that was not sustained for 2 years, whereas 34% of patients benefited from an improvement sustained for longer than 2 years, irrespective of the operation performed (P = 0.143). Only 47%, with hindsight, would have undergone surgery. CONCLUSION: These data highlight that snoring surgery has a high postoperative morbidity rate and a high failure rate. Research endeavors should be directed to the development of a strategy which enables reliable preoperative identification of patients' who enjoy sustained benefit postoperatively.

Acoustic analysis of snoring before and after palatal surgery.

To investigate the effectiveness of palatal surgery for nonapnoeic snoring, 35 patients were block randomised to undergo one of two different palatoplasty procedures. Patients were admitted pre-operatively for audio recording of snoring sound and video recording of sleeping position, and between 1.0 and 4.1 months (mean 2.5) and between 5.9 and 17.5 months (mean 9.7) post-operatively. Sound files, comprising the inspiratory sound of the first 100 snores whilst sleeping in a supine position, were analysed using specifically designed software. Snore duration (s), loudness (dBA), periodicity (%) and energy ratios for the frequency bands 0-200 Hz, 0-250 Hz and 0-400 Hz were calculated. Subjective outcomes were noted. Operation type, body mass index, age, peak nasal inspiratory flow rate, Epworth sleep score and alcohol intake were considered as confounding variables. No patient was cured from snoring. Paired t-test analysis demonstrated statistically significant changes between pre- and early post-operative recordings for snore periodicity and energy ratios in the frequency ranges 0-200 Hz, 0-250 Hz and 0-400 Hz. In conclusion, only the 0-250-Hz energy ratio measurements maintained a statistically significant improvement at the time of the late post-operative recording, despite an obvious drift back to pre-operative levels. No confounding variables were identified. The subjective and objective results correlated poorly. Post-operative changes in the acoustic parameters of snoring sound, following palatal surgery, are demonstrable but short-lived.

Antimicrobial management of acute exacerbation of chronic airflow limitation.

Antibiotics are frequently administered for exacerbations of chronic obstructive pulmonary disease and asthma, yet their role remains unclear. We prospectively audited the antimicrobial management of 167 patients aged >50 years hospitalized for exacerbations of chronic airflow limitation. Antibiotics were commenced on admission for 151 (90%) patients (oral 52%, intravenous 38%), including 17/23 (74%) with no evidence of fever, purulent sputum, leucocytosis or inflammatory chest X-ray changes. The mean number of different antibiotics prescribed was 1.8 (range 0-6); a wide range of antibiotics and antibiotic combinations were used. Sputum samples were sent for microbiological examination in 101 (61%) patients. Sputum culture was positive in 34, but only 11 (7% of the total) had amoxycillin-resistant organisms in their sputum. Seventeen patients (10%) developed diarrhoea while in hospital. Under logistic regression analysis, total number of antibiotics prescribed (p<0.0001) and age (p=0.0062) were the two factors associated with hospital-acquired diarrhoea. Only 34% of patients had received an influenza vaccination in the winter of the study, and 10% a pneumococcal vaccination within the last 5 years. In routine clinical practice, aggressive antibiotic therapy was frequently administered to patients admitted with chronic airflow limitation, despite limited clinical, radiological and microbial indications. Excessive use of antibiotics has important implications, including morbidity (antibiotic-associated diarrhoea), cost and the potential for increased microbial antibiotic resistance. A minority of patients with chronic airflow limitation are being vaccinated against influenza and Pneumococcus.

Objective assessment of hoarseness by measuring jitter.

The objective measurement of hoarseness by measuring 'jitter' (the average percentage pitch-period variation between consecutive pitch-cycles) using an inverse filtering technique is described. Twenty-five patients with a variety of causes of hoarseness were studied, together with five individuals who had mild hoarseness induced by histamine challenge and 12 normal individuals. The mean severity of jitter in the patient group (9.8%) was significantly different from the normals. (1.04%) In addition, there was a significant correlation (R2 = 0.53; P < 0.0001) between jitter and subjective assessment of hoarseness. The mean values of jitter with histamine challenge before and after recovery (1.03%, and 1.18%) were significantly different (P < 0.0001) to the mean maximum value during the challenge (2.64%). These data suggest that jitter is an objective and repeatable measurement of hoarseness-even small changes in hoarseness in individual patients. It is likely to prove most effective for monitoring treatment response.

Oral corticosteroid trials in the management of stable chronic obstructive pulmonary disease.

Although recent guidelines for managing chronic obstructive pulmonary disease (COPD) recommend a trial of oral corticosteroids in the initial assessment, its prognostic value remains unclear. We prospectively studied 127 adults (64% men) with stable COPD (FEV1/FVC < 60%) over 1 year. At entry, we measured lung volumes, gas transfer factor, respiratory symptoms (by questionnaire), and peripheral blood eosinophil count. Skin-prick testing was done, and spirometry after nebulized 5 mg salbutamol and, after 2 weeks, oral prednisolone. Physician A gave all patients inhaled beclomethasone dipropionate (800 mcg/day), whereas physician B prescribed this only to those with a positive oral corticosteroid trial. At 1 year, spirometry and respiratory questionnaire were repeated, with an estimate of overall symptom severity on a visual analogue scale. Follow-up data were available in 104 (82%) patients. Of these, 32 (31%) were unresponsive to salbutamol and prednisolone; 48 (46%) were responsive to beta agonists but not to corticosteroids, and 24 (23%) responded to corticosteroids and salbutamol. Patients in all groups were comparable, except that the prednisolone responders had a higher mean eosinophil count (p < 0.001) and more were ex-smokers (p < 0.001). Only the response to oral prednisolone correlated with the change in prebronchodilator FEV1 over 1 year. Oral prednisolone responders had higher FEV1 at 1 year (p < 0.02) and significantly lower symptom scores (p < 0.02). In COPD, corticosteroid trials contribute information additional to that gained from nebulized bronchodilator reversibility testing. Patients with a positive response to a corticosteroid trial are more likely to have improved symptomatically and spirometrically at 1 year.

Real time analysis of lung sounds.

This paper describes a real time system for the analysis of pulmonary sounds. The system performs various types of time-domain and spectrographic analysis. It is able to display time-domain waveforms obtained from microphones detecting lung sounds, their power spectra and a real-time linear prediction model instantaneously for the immediate identification of interesting features. Details of the system are presented with examples of clinical research carried out using spectrographic analysis.

Inverse filtering applied to upper airway sounds.

Inverse filtering is a digital signal processing technique which may be applied to speech-like sounds to remove resonances introduced by upper airway cavities to leave a residual signal which is, in principle, spectrally flat and strongly related to the excitation source. The filter parameters, normally computed by a form of linear prediction analysis, are indicative of the frequencies and bandwidths of the resonances. This paper briefly outlines the principle of inverse filtering and describes two applications in the study of upper airway sounds for diagnostic purposes. The first application is concerned with the non-invasive measurement of variations in upper airway dimensions which occur with changes in posture. Results show that differences in the resonance frequencies caused by changes in posture can be measured, these being of the order of about 10% in normals. The measurement of such changes is known to be useful in the assessment of patients with sleep apnoea. The second application concerns the evaluation of vocal tract abnormalities resulting from infection in the larynx. Parameters derived from the residual are believed to be indicative of the existence and severity of a hoarse voice. Results have been obtained which support this theory.

A vibrating trachea.

A case of relapsing polychondritis presenting as tracheomalacia is reported in which an unusual low pitched sound was heard at the mouth and over the chest wall during expiration. The sound was associated with expiratory airflow limitation and oscillation on the flow trace of approximately 50 Hz. Spectral analysis of the sound showed it to have the characteristics of sounds produced by flutter in flow limited flexible tubes. These observations suggest that the sound was produced by airflow induced flutter in the trachea and main airways and is further evidence in support of the dynamic flutter theory of wheeze production.

Estimation of analogue pre-filtering characteristics for CORSA standardisation.

This paper is concerned with devising a standard procedure for determining the gain and phase responses of the analogue filters used to pre-process pulmonary signals prior to their digitisation. The customary high-pass filtering, in particular, will strongly affect the time-domain wave-shapes of digitised signals and this must be taken into account when analysing the signals. Several means of determining the effect of the high-pass filtering are investigated and a measurement procedure is proposed which may be easily carried out using simple laboratory equipment.

Cardiovascular consequences of fibreoptic bronchoscopy.

Fibreoptic bronchoscopy (FOB) is now commonly performed, and the number of elderly patients undergoing the procedure is increasing. Problems with oxygenation during FOB are well-recognised, but there are few data about its cardiovascular effects. Forty five patients (median age 65 yrs) undergoing elective FOB were studied prospectively. Patients were connected to a 12-lead computerized electrocardiographic recorder, a finger plethysmographic blood pressure (FPBP) monitor and pulse oximeter. Forty three patients were sedated with fentanyl and droperidol, and all were given 5 mL 2.5% cocaine intratracheally and xylocaine spray to the pharynx. Mean sphygmomanometric cuff blood pressure was raised initially (167/88 mmHg). Mean blood pressure recorded by FPBP rose on intratracheal injection (178/96 mmHg) and remained high throughout the procedure. Mean (SD) initial cardiac frequency was 93 (5.1) beats x min(-1) and rose to 134 (7.5) beats x min(-1) during the procedure. Four of the 45 patients showed unexpected ST segment depression of >1 mm for >1 min, and a further three developed bundle branch block. These seven patients had significantly greater tachycardia (152 vs 131 beats x min(-1)) and higher blood pressure (238/131 vs 207/109 mmHg). They were older (72 vs 61 yrs), had smoked more (63 vs 39 pack-years), but had similar lung function and similar changes in oxygen saturation. Oxygen desaturation occurred in 19 patients and this was associated with poor lung function (69 vs 84% predicted forced expiratory volume in one second), but was independent of the cardiovascular changes. Significant cardiovascular changes occur during fibreoptic bronchoscopy, with evidence of cardiac strain in 21% of patients over the age of 60 yrs.

The acoustic properties of capsaicin-induced cough in healthy subjects.

Acoustic analysis of cough both in the time and frequency domain has been reported using voluntary and spontaneous cough. The main aim of this study was to discover whether such analysis of capsaicin-induced cough enables differences between normal subjects to be recognized. We present data from 13 healthy subjects (with normal lung function and no history of respiratory disease) using a new method of acoustic analysis, which presents the data in three graphical forms: 1) spectrogram; 2) overall spectral energy, 3) root mean square (RMS) pressure plots. Using the RMS sound pressure traces, different subjects had either two peaks, a single peak or multiple peaks. The occurrence of single and multiple peaks has previously been associated with disease states but we found them in normal subjects. The number of peaks and the visual pattern of the spectrogram was reproducible within and specific to each individual over time. During a peal of coughs in a single expiration, the peak amplitude of successive coughs decreased as lung volume reduced. Despite similarities in the overall spectral energy between individuals, there were marked differences in the small visual details of the spectrograms. However, in an individual, these small details were remarkably constant both within and between days, and can be regarded as a "cough signature". This type of spectrographic analysis provides a new approach to the analysis both of normal and abnormal cough sounds, and has identified similarities and differences in capsaicin-induced cough in normal individuals. It has potential as a tool with which to study the pathophysiology of cough.

The relationship between wheezing and lung mechanics during methacholine-induced bronchoconstriction in asthmatic subjects.

Wheeze is a classic sign of airflow obstruction but relatively little is known of its mechanism of production or its relationship to the development of airflow obstruction. We studied eight asthmatic subjects age (mean +/- 5D) 42 +/- 5 yr, FEV1 2.46 +/- 0.36 L during an extended, symptom-limited methacholine challenge test. Breath sounds were detected by a microphone over the right upper anterior chest. Spectral analysis was by a fast Fourier transform algorithm. Mean FEV1 fell by 51 +/- 14% to 1.28 +/- 0.61 L during the challenge and airways resistance increased by 119 +/- 50%. There were no consistent changes in breathing pattern or tidal volume during the challenge. Wheeze occurred late in the challenge at the highest concentration of methacholine administered and only after expiratory tidal flow limitation had been reached. Five subjects developed wheeze on tidal breathing, the remaining three only wheezed on deep breathing. Wheezing sounds were reproducible between breaths, coefficient of variation of starting sound frequency was 4.2% and ending frequency 12%. Mean frequency of expiratory wheezes was 669 +/- 100 Hz and inspiratory wheezes 710 +/- 76 Hz. Expiratory wheeze fell in pitch during a breath (mean fall in sound frequency 187 +/- 43 Hz) but inspiratory wheezes were more variable. Expiratory wheezes occurred late in the respiratory cycle at a mean of 58% of the maximal tidal expiratory flow, whereas inspiratory wheezes occurred around maximal tidal inspiratory flows, suggesting that the mechanisms of production of inspiratory and expiratory wheezes may be different. In this model, the presence of wheeze during tidal breathing was a sign of severe airflow limitation.

Arousal responses from apneic events during non-rapid-eye-movement sleep.

Patients with obstructive sleep apnea (OSA) experience severe sleep disruption and consequent daytime sleepiness. Current arousal scoring criteria show that some obstructive apneic events do not end in a recognizable cortical electroencephalographic (EEG) arousal. It is not known whether events that end in an obvious EEG arousal differ from those that do not, in terms of EEG frequency changes during the apneic event, the respiratory effort developed prior to apnea termination, the degree of the postapneic increase in blood pressure, or changes in CO2 tensions. We studied 15 patients with OSA in early Stage 2 sleep and analyzed obstructive apneic events with and without typical EEG arousals, defining an arousal as a frequency shift to waking alpha rhythm of 1 s or longer. EEG signals were digitized and analyzed by fast Fourier transform during and immediately after each apnea. The median EEG frequency and mean pleural pressure of the first and second halves of the apneic episode were compared with that of the first breath. Peak pleural pressure was measured just before the end of the apneic episode. Systolic and diastolic blood pressures and CO2 tensions were measured at the onset and termination of apnea. For each patient, 10 events that ended in EEG arousal were compared with 10 events that did not. Mean apnea duration did not differ for the two groups of events. Median EEG frequency and pleural pressure increased significantly from 8.14 to 9.25 Hz and 15.4 to 22.1 cm H2O, respectively, as the apnea progressed, but there was no difference between the groups nor any difference in the peak pleural pressure.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison of three different methods used to achieve local anesthesia for fiberoptic bronchoscopy.

A patient's tolerance of fiberoptic bronchoscopy depends on the effectiveness of local anesthesia. This study compares the three different methods of local anesthesia in common use After sedation, patients (n = 53) received either 4 ml of 2.5 percent cocaine by intratracheal injection (TI) (n = 18), by bronchoscopic injection (BI) (n = 19), or had 4 ml of 4 percent lidocaine delivered by nebulizer 20 min before the procedure (NEB) (n = 16). Patients and bronchoscopists scored the procedure using visual analog (VAS) and severity scales. Objective measurements of cough counts and episodes of stridor were recorded by phonopneumography. Patients' VAS scores showed a clear preference for the transtracheal method compared with either bronchoscopically injected cocaine (p less than 0.001) or nebulized lidocaine (p less than 0.001). Patients also reported that the TI method produced less cough during intubation of the larynx and inspection of the airways (BI and NEB, p less than 0.01). The TI method was also preferred by the bronchoscopists (BI and NEB, p less than 0.001); they reported less cough and easier tracheal intubation. The mean cough count was significantly lower for the TI group, 49 (43) compared with 95 (52) for BI (p less than 0.01), and 81 (43) for the NEB group (p less than 0.05). Patients' and bronchoscopists' VAS showed significant correlation with cough (r = 0.63-69, p less than 0.01). Stridor occurred in only two patients after TI, compared with 15 in the other two groups. Extra local anesthesia was required by 16 patients after BI, by all the NEB group, but by only one patient after TI. Subjective and objective measurement shows that 4 ml of 2.5 percent cocaine injected into the trachea produced excellent local anesthesia for fiberoptic bronchoscopy, there were no extra complications, and it was the method preferred by both patients and bronchoscopists.

Acute bronchodilator trials in chronic obstructive pulmonary disease.

Short-term trials of bronchodilator drugs are widely used to assess patients with stable chronic obstructive pulmonary disease (COPD), but there is an uncertainty about the equivalence of the FEV1 response to beta-agonists and anticholinergic drugs, their relative ability to identify patients likely to improve with corticosteroids, the most appropriate way to express the results of these tests, and whether age or allergic status affects the beta-agonist and anticholinergic response differently. We studied 100 consecutive patients with stable COPD (mean FEV1, 0.96 +/- 0.48 L; mean age, 62 +/- 8 yr). Spirometry was measured before and after either 5 mg of nebulized salbutamol or 500 micrograms of nebulized ipratropium bromide and repeated after 2 wk of 30 mg of oral prednisolone daily. Total IgE, specific RAST, and skin prick testing values were recorded. Using modified American Thoracic Society response criteria, 33 patients failed to bronchodilate after the acute trials, 16 responded only to nebulized salbutamol, 17 to nebulized ipratropium, and 34 to both drugs. Twenty-two patients improved after corticosteroids. This was usually detected by a positive acute trial response (salbutamol 90% specific; ipratropium 84% specific). Baseline FEV1 differed between days, and in those who responded on only 1 day, this variation correlating with the response to ipratropium (r = 0.66). Expressing the response criterion as a percentage change in the available bronchodilatation increased the numbers responding with a high baseline FEV1, and vice versa. Neither age nor allergic status was related to the change in FEV1 after either drug in these patients. In COPD patients, testing with high-dose nebulized bronchodilators identifies a substantial number of partially reversible patients whatever age it is employed.(ABSTRACT TRUNCATED AT 250 WORDS)

A mask to modify inspired air temperature and humidity and its effect on exercise induced asthma.

BACKGROUND: Heat and moisture loss from the respiratory tract during exercise are important triggers of exercise induced asthma. METHODS: A new heat and moisture exchange mask has been developed which both recovers exhaled heat and water and has a sufficiently low resistance for use during exercise. The effect of the mask on inspired air temperature was studied in four normal subjects. Eight asthmatic subjects performed identical exercise protocols on three separate days, breathing room air through a conventional mouthpiece, a dummy mask, and the new heat and moisture exchange mask. Seven different asthmatic subjects exercised while breathing cold air at -13 degrees C through a dummy or active mask. RESULTS: All subjects found the new mask comfortable to wear. The mean inspired temperature when the mask was used rose to 32.5 (1.4) degrees C when normal subjects breathed room air at 24 degrees C and to 19.1 (2.7) degrees C when they inhaled subfreezing air at -13 degrees C. The heat and moisture exchange mask significantly reduced the median fall in forced expiratory volume in one second (FEV1) after exercise to 13% (range 0-49%) when asthmatic subjects breathed room air compared with 33% (10-65%) with the dummy mask and 28% (21-70%) with the mouthpiece. The fall in FEV1 when the asthmatic subjects breathed cold air was 10% (0-26%) with the heat and moisture exchange mask compared with 22% (13-51%) with the dummy mask. CONCLUSION: Use of a heat and moisture exchange mask can raise the inspired temperature and humidity and ameliorate the severity of exercise induced asthma. The mask may be of practical value in non-contact sport or for people working in subzero temperatures.

Assessment of reversibility of airway obstruction in patients with chronic obstructive airways disease.

Spirometry before and after an inhaled beta agonist or a course of oral prednisolone is widely used to detect reversible airflow limitation in patients with chronic obstructive lung disease. How many of these patients have a response and how the response to beta agonists relates to the response to corticosteroids is not clear. In 127 outpatients (mean (SD) FEV1 0.92 (0.38) 1) who had a clinical diagnosis of chronic obstructive lung disease (continuous breathlessness for more than six months and an FEV1/forced vital capacity (FVC) ratio less than 60%) and who appeared to be stable, the change in FEV1 was measured after salbutamol 200 micrograms from a metered dose inhaler and 5 mg from a nebuliser. Symptoms and spirometric values were recorded before and after two weeks of oral prednisolone 30 mg. Reversibility was defined as a response in FEV1 of 15% or more from baseline alone and as a 15% change and a minimum increase of at least 200 ml. The latter gave results that showed greater internal consistency between the drug regimens. On the basis of this criterion 56 patients (44%) had no response to salbutamol or prednisolone, 71 responded to salbutamol (including all 27 steroid responders), and 25 patients had a response to salbutamol 5 mg but not to 200 micrograms. In general, the largest increase in FEV1 after salbutamol occurred in the subjects with greatest improvement after prednisolone. Subjects showing a response in FEV1 after two weeks' prednisolone had a fall in total symptom score, unlike those who had no response to any treatment or a response to salbutamol only. These data show that reversibility in response to beta agonists is common in patients diagnosed on clinical grounds as having stable chronic obstructive lung disease, that it can be substantial, and that it is best detected by using a larger dose of salbutamol. Salbutamol responders were those most likely to improve after a trial of oral prednisolone. Allowance should be made for the variability of FEV1 in the calculation of the percentage response at low baseline values (less than 1 litre).