The use of nasal spirometry as an objective measure of nasal septal deviation and the effectiveness of septal surgery

Nasal spirometry, after decongestion, was used to assess the severity of septal deviation in 31 patients before and after nasal septal surgery. Patients were divided into two groups on the basis of their preoperative nasal partitioning of airflow ratio (NPR). The NPR ranges from 0.00 (equality of airflow) to 1.00 (total unilateral obstruction) with the normal range defined as 0.00-0.34. In 14 patients with a preoperative NPR within the normal range, the median NPR was not influenced by surgery (preop 0.14 to postop 0.12, P= 0.07). In 17 patients with a preoperative NPR outside the normal range, there was a significant reduction of the median NPR after surgery (preop 0.50 to postop 0.16, P < 0.01). The correlation of NPR with subjective assessment of the deviation was r = 0.85 (P < 0.01), and with patient subjective symptom assessment r= 0.94 (P < 0.01) preoperatively and r= 0.51 (P < 0.01) postoperatively. The findings indicate that nasal spirometry may be useful in patient selection for septal surgery.

The use of nasal spirometry for the assessment of unilateral nasal obstruction associated with changes in posture in healthy subjects and subjects with upper respiratory tract infection

Nasal spirometry was used to measure the effect of acute rhinitis associated with upper respiratory tract infection (URTI) on the changes in nasal airflow that occur with postural change. Results in 12 healthy subjects and 12 subjects with URTI were expressed as the nasal partitioning of airflow ratio (NPR), a new measure of nasal airflow. Values of NPR range from 0 (equality of airflow) to 1 (unilateral nasal obstruction). In subjects with URTI there was a significant change (P < 0.006) in the median NPR from 0.19 sitting to 0.87 supine, with five subjects having complete unilateral nasal obstruction. The change in the median NPR in the healthy subjects from 0.09 sitting to 0.13 supine was not significant. The results illustrate the incidence of complete unilateral nasal obstruction associated with URTI when lying flat and demonstrate the usefulness of nasal spirometry in studying nasal airflow partitioning in health and disease.

The powerful placebo in cough studies?

Placebo treatment has been reported to improve subjective and objective measures of disease in up to 30-40% of patients with a wide range of clinical conditions. A review of 8 clinical trials on the effects of antitussive medicines on cough associated with acute upper respiratory tract infection shows that 85% of the reduction in cough is related to treatment with placebo, and only 15% attributable to the active ingredient Treatment with a cough medicine can be viewed as consisting of three components: pharmacological, physiological (demulcent) and placebo. The placebo effect is related to belief in the effectiveness of the treatment and this idea must in some way influence the central control of cough. Studies on the placebo effect of analgesics indicate that the placebo effect may be mediated by endogenous opioid neurotransmitters and this may explain the analgesic potency of opioid medicines such as morphine. In the present paper a model is proposed to explain the antitussive effects of placebo treatment on the basis of endogenous opioid neurotransmitters. With active pharmacological ingredients contributing only 15% to the effects of cough treatment it seems reasonable to conduct more research on the other components of treatment such as placebo.

Voluntary control of cough

Cough is normally referred to a reflex mediated by control centres in the respiratory areas of the brainstem. However, there is much experimental information that indicates that human cough is under voluntary control and that higher centres such as the cerebral cortex have an important role in both initiating and inhibiting cough. Studies on acute cough associated with common cold, and capsaicin induced cough have demonstrated that human cough can be voluntarily inhibited and often abolished. Further evidence for some role of consciousness in the control of cough comes from studies that show that cough is inhibited or abolished during sleep and with light anaesthesia. This paper discusses the historical development of the brainstem 'cough centre' and discusses the experimental evidence on the voluntary control of cough in man. A cough model demonstrating the voluntary and reflex control of cough in man is proposed. A hypothesis is proposed that cough associated with common cold is a mixture of both reflex and voluntary cough.

Acute cooling of the body surface and the common cold

There is a widely held belief that acute viral respiratory infections are the result of a "chill" and that the onset of a respiratory infection such as the common cold is often associated with acute cooling of the body surface, especially as the result of wet clothes and hair. However, experiments involving inoculation of common cold viruses into the nose, and periods of cold exposure, have failed to demonstrate any effect of cold exposure on susceptibility to infection with common cold viruses. Present scientific opinion dismisses any cause-and-effect relationship between acute cooling of the body surface and common cold. This review proposes a hypothesis; that acute cooling of the body surface causes reflex vasoconstriction in the nose and upper airways, and that this vasoconstrictor response may inhibit respiratory defence and cause the onset of common cold symptoms by converting an asymptomatic subclinical viral infection into a symptomatic clinical infection.

An explanation for the seasonality of acute upper respiratory tract viral infections

Despite a great increase in our understanding of the molecular biology of the viruses associated with acute upper respiratory tract viral infections (URTIs) there is a remarkable lack of knowledge and ideas about why URTI should exhibit a seasonal incidence. Most publications in this area either acknowledge a complete lack of any explanation for the seasonality of URTI or put forward an explanation relating to an increased "crowding" of susceptible persons in winter. This review will discuss some of the ideas concerning the seasonality of URTI and put forward a new hypothesis for discussion, namely that seasonal exposure to cold air causes an increase in the incidence of URTI due to cooling of the nasal airway. The hypothesis is supported by literature reports demonstrating that inhalation of cold air causes cooling of the nasal epithelium, and that this reduction in nasal temperature is sufficient to inhibit respiratory defences against infection such as mucociliary clearance and the phagocytic activity of leukocytes. A case is also made to suggest that warming of the nasal airway during fever and nasal congestion may help to resolve a current URTI.

An explanation for the seasonality of acute upper respiratory tract viral infections

Despite a great increase in our understanding of the molecular biology of the viruses associated with acute upper respiratory tract viral infections (URTIs) there is a remarkable lack of knowledge and ideas about why URTI should exhibit a seasonal incidence. Most publications in this area either acknowledge a complete lack of any explanation for the seasonality of URTI or put forward an explanation relating to an increased "crowding" of susceptible persons in winter. This review will discuss some of the ideas concerning the seasonality of URTI and put forward a new hypothesis for discussion, namely that seasonal exposure to cold air causes an increase in the incidence of URTI due to cooling of the nasal airway. The hypothesis is supported by literature reports demonstrating that inhalation of cold air causes cooling of the nasal epithelium, and that this reduction in nasal temperature is sufficient to inhibit respiratory defences against infection such as mucociliary clearance and the phagocytic activity of leukocytes. A case is also made to suggest that warming of the nasal airway during fever and nasal congestion may help to resolve a current URTI.

Use of a portable spirometer for studies on the nasal cycle

Studies based on the nasal cycle are difficult because multiple measurements of nasal patency need to be made over many hours. There is a great need for a simple portable instrument that can be used away from the clinical laboratory for studies on the nasal cycle. Our aim was to investigate the usefulness of a small portable spirometer in studying the nasal cycle. The Mir Spirobank spirometer was fitted with a nasal adapter to measure the volume of air expired from each nasal passage during a slow vital capacity (VC). The spirometer was used to measure the fractions of the slow VC volume of air expired through the right and left nasal passage in turn. Hourly measurements were made over a 5-hour period in six healthy volunteers. The spirometry measurements of the volume of air expired from each nasal passage were compared with nasal conductance of each nasal passage (airflow at 75 Pa) obtained by posterior rhinomanometry. The spirometer was found easy to use by both the investigator and the patients. Simple regression analysis of the spirometer and rhinomanometer measures of airflow partitioning found a correlation coefficient of r = 0.827 (p < 0.0001: n = 36). These results indicate that the partitioning of nasal expired volume measured by spirometry is directly comparable with partitioning of nasal airflow obtained with rhinomanometry. Spirometry has considerable advantages over rhinomanometry for studies on the nasal cycle because of portability and ease of use.

Pathophysiology of nasal symptoms

Symptoms are perceived by the patient and all nasal symptoms must eventually relate to stimulation of sensory nerves or some change in the activity of the CNS. Although it is the symptoms that are of prime importance to the patient, the role of sensory nerves and psychology in the generation and perception of symptoms has been relatively neglected compared to the large amount of research on inflammatory mediators. This paper discusses how physical and chemical changes in the nasal epithelium result in the generation of inflammatory mediators that are responsible for symptoms. Inflammatory mediators can cause symptoms in three ways. (1) By having direct action on glands and blood vessels to cause glandular secretion, vasodilation, increased vascular permeability, and transudation of a plasma exudate. (2) By stimulation of sensory nerve endings to cause reflex glandular secretion, sneezing, and sensations such as itching, irritation, pain, and pressure. (3) By effects on the central nervous system to cause, headache, fever, tiredness, and mood changes.

Antitussive efficacy of dextromethorphan in cough associated with acute upper respiratory tract infection

Dextromethorphan is one of the most widely used antitussives for the treatment of cough associated with acute upper respiratory tract infection. However, there is very little data to support the efficacy of dextromethorphan in this disease state. This aim of this study was to obtain more information about the efficacy of a single dose of 30 mg dextromethorphan in the treatment of cough associated with acute upper respiratory tract infection. The study was a double-blind, stratified, randomized and parallel group design. Both objective and subjective measurements of cough were recorded over 10-min recording periods in a quiet room before (baseline) and at 90, 135 and 180 min after treatment. Forty-three patients (30 females and 13 males), mean age 22.9 years (range 18-46 years), with acute dry or slightly productive cough and otherwise healthy were included in the study. Patients were randomized to placebo treatment (n = 22) and dextromethorphan treatment (n=21). The results showed similar trends in both treatment groups with statistically significant reductions (P < 0.05) in cough sound pressure level (CSPL), cough frequency (CF) and subjective scores for cough severity within treatment groups but little difference between the treatment groups during the study period. The only statistically significant difference between treatment groups was for the mean CSPL changes from baseline to 90 min (P=0.019). There was a significant positive correlation between CSPL and CF (r = 0.752, P= 0.000) for changes in cough measurements from baseline to 90 min after treatment and this indicates that CSPL may be a useful measure of cough severity. This study provides very little if any support for clinically significant antitussive activity of a single 30 mg dose of dextromethorphan in patients with cough associated with acute upper respiratory tract infection.

Nasal airflow in health and disease

This review examines our present understanding of the physiology, pathophysiology and pharmacology of nasal airflow. The main aim of the review is to discuss the basic scientific and clinical knowledge that is essential for a proper understanding of the usefulness of measurements of nasal airflow in the clinical practice of rhinology. The review concludes with a discussion of the measurement of nasal airflow to assess the efficacy of surgery in the treatment of nasal obstruction. Areas covered by the review include: influence of nasal blood vessels on nasal airflow; nasal valve and control of nasal airflow; autonomic control of nasal airflow; normal nasal airflow; nasal cycle; central control of nasal airflow; effect of changes in posture on nasal airflow; effect of exercise on nasal airflow; effect of hyperventilation and rebreathing on nasal airflow; nasal airflow in animals; cerebral effects of nasal airflow; sensation of nasal airflow; sympathomimetics and sympatholytics; histamine and antihistamines; bradykinin; and corticosteroids.

Effect of submucosal diathermy to the inferior turbinates on unilateral and total nasal airflow in patients with rhinitis

The efficacy of the controversial treatment of submucosal diathermy to the inferior turbinates (SMDIT) was evaluated objectively. Twenty-seven patients with chronic rhinitis were investigated by hourly posterior rhinomanometry to assess changes in total and minimum (Fmin) and maximum (Fmax) unilateral nasal airflow over 5 h, before and 2-3 months after standardized SMDIT treatment. Nasal airflow was recorded at a sample pressure of 75 Pa and the results are reported as medians with interquartile range. Whilst SMDIT caused a significant 51% increase (p < 0.0001) in total nasal airflow from 246 cm3/s (131) to 371 cm3/s (133) the changes in unilateral airflow provided further evidence which strongly supported the benefits of this operation. Unilateral Fmin significantly increased by 136% (p < 0.0001) from 69 cm3/s (82) to 163 cm3/s (74) and Fmax significantly increased by 23% (p < 0.0001) from 171 cm3/s (74) to 211 cm3/s (59). The effect of surgery was to "splint" to the turbinate in a state of relative vasoconstriction. Our findings therefore provide functional evidence of submucosal fibrosis following SMDIT. The greater percentage change in unilateral Fmin suggests that this parameter is a more sensitive index of the effect of nasal surgery than total nasal airflow measurements. The importance of considering the nose as two separate airways in the evaluation of nasal treatments is emphasized.

Coughing and choking in motor neuron disease

OBJECTIVES

To assess the frequency and severity of coughing and choking episodes, possible related factors, and their association with chest infections in patients with motor neuron disease (MND).

METHODS

Thirty seven patients with MND and 23 healthy volunteers were studied. Cough was assessed using a questionnaire and a 3 day diary, and volitional cough quantified by peak cough flow and sound intensity. Other clinical symptoms, smoking habit, affective state, oral secretions, bulbar signs, and quantitative assessments of swallowing and respiratory function were documented.

RESULTS

Patients with MND coughed and choked significantly more often and to a greater degree than the healthy volunteers (26 of 37 patients with MND and 2 of 23 volunteers, p<0.001). Female sex, older age, abnormal speech, reduced swallowing capacity, and low forced vital capacity (FVC)% predicted were each significantly associated with excessive coughing and choking episodes in patients with MND. Smokers had significantly more severe and prolonged episodes of coughing and choking than non-smokers (p<0.05). Patients with upper motor neuron bulbar signs had a greater tendency to severe and prolonged episodes of coughing and choking than those without (p<0. 05). Chest infections were reported only rarely among the patients who coughed and choked.

CONCLUSIONS

Coughing and choking episodes are common in patients with MND but infrequently associated with overt chest infection. Upper motor neuron bulbar signs may both promote factors (for instance, dysphagia) which trigger cough and reduce volitional capacity to suppress it.

Changes in unilateral nasal airflow in patients with seasonal allergic rhinitis measured in and out of season

OBJECTIVE

Nasal congestion is a common complaint of patients suffering from seasonal allergic rhinitis yet there are very few investigations which have studied the objective changes in nasal airflow in and out of season. The aim of this study was to investigate the changes in nasal airflow in and out of season.

METHODS

In the present study unilateral nasal airflow was measured in and out of the pollen season in 13 patients with seasonal allergic rhinitis. Unilateral nasal airflow was measured using posterior rhinomanometry at an inspiratory reference pressure of 75 Pa.

RESULTS

There was no significant difference between median total nasal airflow in season (325 cm3/s) and out of season (324 cm3/s) (P = 0.15, n = 13) yet there was a significant difference between maximum unilateral airflow in season (278 cm3/s) and out of season (234 cm3/s) (P = 0.007, n = 26).

CONCLUSION

The results of the present study indicate that although patients with seasonal allergic rhinitis may experience a sensation of nasal congestion at the start of the pollen season there is little or no change in total nasal airflow and unilateral nasal airflow may be increased.

Role of cold receptors and menthol in thirst, the drive to breathe and arousal

Menthol is widely used in candy, chewing gum, toothpastes, cigarettes and common cold medications. Menthol has been shown to stimulate cold receptors in the mouth and nose. The present paper puts forward the hypothesis that menthol, by its effects on oral and nasal cold receptors, may influence thirst, the drive to breathe, and arousal. The satisfying effects of menthol on thirst and breathing, together with an effect on arousal, may explain the popularity of menthol and account for the very large amount of menthol-containing products that are consumed each day.

The effects of nasal massage of the "yingxiang" acupuncture point on nasal airway resistance and sensation of nasal airflow in patients with nasal congestion associated with acute upper respiratory tract infection

The aim of our study was to determine whether nasal massage of the "yingxiang" acupuncture point in patients with nasal congestion had any effect on nasal airway resistance (NAR) measured by posterior rhinomanometry and sensation of nasal airflow measured on a visual analog scale (VAS). Twenty patients were randomized into two groups; one group self massaged the yingxiang point for 30 seconds, while the other group acted as control group without nasal massage. NAR and VAS were measured at baseline, and at 2 and 10 minutes after massage. At the end of the study, patients were asked to score any change in their nasal congestion. There was no statistically significant difference between the two groups in percentage change in NAR or VAS from baseline at any time during the study, although the massage group showed trends toward decongestion and relief from congestion. At the end of the study, more patients in the massage group than the control group felt their nasal congestion was improved (p < 0.005). It is interesting that all three measures (NAR, VAS, and end question) showed that the nasal massage group had greater relief from nasal congestion than the control group. The results of this study, when taken together, indicate that nasal massage may provide some relief from nasal congestion and that further studies involving a larger patient population are warranted to determine whether nasal massage has a significant effect on NAR.

Effect of pseudoephedrine on nasal airflow in patients with nasal congestion associated with common cold

The aim of this study was to investigate the efficacy of pseudoephedrine as a nasal decongestant. Patients with nasal congestion associated with common cold received two doses of medication separated by 4 hours, either 60 mg pseudoephedrine (n = 20), or placebo (n = 20). Unilateral nasal airflow was measured over a 7-hour period to record the spontaneous changes in nasal airflow associated with the nasal cycle. Minimum (F MIN) and maximum (F MAX) unilateral nasal airflows were defined as the minimum and maximum nasal airflow values for each nasal passage recorded during the 7-hour period of the study. There was no significant difference in F MAX between the two treatment groups yet there was a significant difference in F MIN (p < 0.05). No difference in total nasal airflow (TNAF) between treatment groups was found, either before or after treatment (p > 0.05). The results demonstrate that (TNAF) is not as sensitive a measure of decongestion as F MIN. The findings of this study show that pseudoephedrine had no effect on the decongestion phase of the nasal cycle, but did significantly limit the congestion phase. The decongestant action may be explained by the sympathomimetic supplementing the natural sympathetic nervous activity to the nasal blood vessels.

Development and application of a new method for amplification and detection of human rhinovirus RNA

A method based on nucleic acid sequence based amplification (NASBA) was developed for detection of rhinovirus RNA. Appropriate collection and storage conditions for maintenance of rhinovirus RNA integrity in clinical samples was determined. Two silica-based extraction methods were evaluated for preparation of RNA from virus isolates and clinical samples. Primers and probes were selected from the non-translated region at the 5' end and from VP4 of sequenced rhinoviruses. Amplified products were detected by 'in-solution' hybridization, with analysis by polyacrylamide gel electrophoresis (enzyme linked gel assay or ELGA), and by a microtitre-based plate hybridization assay. Using propagated picornavirus isolates in vitro the rhinovirus NASBA, with detection of amplified sequences by ELGA or plate hybridization, was confirmed as sensitive and specific for detection of rhinovirus RNA. The method was applied successfully to analysis of rhinovirus sequences in clinical samples from individuals with respiratory-tract symptoms. Rhinovirus NASBA will be useful for studies of the molecular epidemiology of respiratory infections and monitoring of response to anti-rhinovirus therapy.

Acoustic rhinometry: an explanation of some common artefacts associated with nasal decongestion

The nasal cavities of 51 healthy volunteers were examined using acoustic rhinometry before and after nasal decongestant. Several specific dimensions were studied, which included the minimum cross-sectional area, and three volumes corresponding to the anterior, middle and posterior regions of the nasal airway. An average acoustic rhinometry trace was constructed for the whole group of subjects, before and after decongestion, from data extracted from the raw data files written to the computer hard disk for each subject. A 27.5% (P < 0.0001) increase in the minimum cross-sectional area was observed, with no shift in its position. The greatest increase in nasal dimensions was seen in the anterior and middle parts of the nose, however, significant changes were also seen in the posterior nasal cavity and post nasal space. There are a number of possible sources of artefact. First, confusion of the first and second minima may produce apparent movement of the minimum cross-sectional area following nasal decongestion. Second, a postulated change in the acoustic path length may lead to apparent changes in volume in certain regions of the nose. Third, a variable and uncontrollable degree of sound energy loss will occur into the opposite nasal cavity beyond the posterior border of the septum. An apparent increase in the dimensions of this region will be seen as the opposite cavity decongests. We feel that all users of the acoustic rhinometer need to be aware of these potential sources of artefact, and attention needs to be focused on an agreed definition of the components of the acoustic rhinometry trace.

Physiological versus pharmacological decongestion of the nose in healthy human subjects

In the present study we were interested to determine whether the maximum unilateral nasal airflow associated with the nasal cycle (Fmax physiol) was equivalent to the maximum unilateral nasal airflow that could be achieved by the application of a topical nasal decongestant (Fmax pharmacol). Eight healthy subjects (three male and five female, aged between 19-28 years) were recruited for this study. Unilateral nasal airflow was measured using posterior rhinomanometry at the inspiratory reference pressure of 75 Pa by alternately occluding each nostril with surgical tape. The study was run over 2 consecutive days. On day one, measurements of unilateral nasal airflow were performed every hour for 8 h in each subject and Fmax physiol was found to be 265 cm3/sec (147) (median and interquartile range). On day 2 the median unilateral nasal airflow before application of the nasal decongestant was 171 cm3/sec (140) and this increased to 251 cm3/sec (127) (p = 0.046) at 15 min and to 278 cm3/sec (134) (p = 0.005) at 45 min after application of the decongestant (Fmax pharmacol). A paired comparison of Fmax physiol and Fmax pharmacol showed that these nasal airflow measurements were not significantly different (p > 0.999). The results show that there was no difference between the maximum physiological decongestion produced during the course of the nasal cycle and that produced pharmacologically by a topical nasal decongestant. This indicates that the point of maximal sympathetic vasoconstrictor tone occurring during the nasal cycle causes a constriction of the nasal venous sinuses that is equal to the constrictor response that can be achieved by applying a topical sympathomimetic medication.

The effects of oxymetazoline on lysozyme secretion from the human nasal mucosa

Lysozyme is a protein secreted by nasal submucosal glands. Its secretion is under cholinergic control. It is considered important in nasal defence as it enzymatically hydrolyses peptidoglycan bonds in bacterial cell walls and has specific activity against Gram-positive bacteria in vitro. Oxymetazoline is freely available as a non-prescription nasal decongestant. Some recent work has shown that it has no effect on histamine-induced plasma exudation but little is known about its effects on glandular secretion. The current study is a randomized controlled study that investigates the effect of topical oxymetazoline on the total protein and lysozyme content of nasal fluid. Thirty healthy volunteers were randomized to receive either a normal saline nasal spray (placebo) or an active spray of oxymetazoline, 0.05% (w/v) in saline. NAR was assessed in all subjects using posterior rhinomanometry and nasal lavage before the application of the spray and again 10 min later. The results were analysed using non-parametric statistics. There was a significant decrease in both the lysozyme and total protein content of nasal lavage after application of oxymetazoline when compared with placebo (p < 0.05). A possible mechanism for the observed decease in total protein and lysozyme would be that the vasoconstrictor effects of oxymetazoline also apply to the vessels supplying nasal submucosal glands and that this decrease in blood supply is reflected by a decrease in secretion.

Assessment of the antitussive efficacy of codeine in cough associated with common cold

Codeine is generally accepted as the standard antitussive against which new antitussive medications are compared. This presents a problem because the support for codeine's antitussive activity comes from studies on cough in animals, and chronic and induced cough models in man, whereas antitussives are almost exclusively used for the treatment of cough associated with acute upper respiratory tract infection (URTI). The aims of this study were twofold. Firstly, to study the antitussive efficacy of codeine in cough associated with URTI and, secondly, to validate a sound meter as tool for quantifying cough. The efficacy of codeine was assessed in a double-blind, stratified, placebo-controlled, parallel-group, clinical trial using three different measures of cough: cough sound-pressure levels (CSPLs) measured on a sound meter; subjective scores of cough severity; and cough frequency recorded by means of a microphone connected to an ink-pen recorder. A group of 82 subjects (51 females and 31 males; mean age 23.5 years, range 18-46 years) with cough owing to acute URTI were included in the study. The study took place on two separate study days. On study day 1 cough measurements were made before and 90 min after treatment with a single dose of either 50 mg codeine or matched placebo in capsule form. The same three measures of cough were repeated 2-5 days later (study day 2). On study day 1 a highly significant (P < 0.0001) decrease in all three measures of cough was found after treatment with both placebo and codeine yet there was no significant difference between the treatment groups. A highly significant (P < 0.0001) decrease in the three measures of cough was also found between days 1 and 2. The results demonstrate that codeine is no more effective than placebo in reducing cough associated with acute URTI, as measured by CSPLs, cough frequency or subjective symptom scores. This result might be explained on the basis of two central pathways for cough; a reflex pathway via the brain-stem which is sensitive to codeine and a voluntary pathway via the cortex which is unaffected by codeine. The results also demonstrate that the sound-level meter appears to be a potentially useful investigative tool for the assessment of cough and antitussive efficacy.