All mammals, including man, have two nasal passages. However, air¯ow is not symmetrical, due to anatomical and physiological factors.The anatomical factors are the ®xed structural dierences between the two nasal passages and the physiological factors are related to spontaneous congestion and decongestion of nasal venous sinuses (venous erectile tissue), often referred to as the nasal cycle. 1 This review will be restricted to the understanding of the physiology and pathophysiology of the`nasal cycle' and a case will be made that these factors must be taken into account when considering the surgical treatment of nasal obstruction.In the clinical assessment of a patient presenting with nasal obstruction the otorhinolaryngologist must consider:(1) the anatomical factors; (2) the physiological factors; and (3) the pathophysiology of the nasal mucosa in relation to in¯ammatory conditions, recumbency and posture. The surgeon, when asked to correct anatomical and physiological abnormalities, should consider the nose as two separate nasal passages that exhibit spontaneous and often reciprocal changes in nasal air¯ow. Physiology of the`nasal cycle' R E C I P R O C I T Y A N D P E R I O D I C I T YIn the healthy nose the ®xed anatomy of the two nasal passages, consisting of bony and cartilaginous components, is symmetrical. However, the air¯ow through the nasal passages is normally asymmetrical and this is the result of spontaneous changes in nasal airway resistance which are often reciprocal in nature. 2,3 These changes normally result in asymmetrical air¯ow that alternates from one nasal passage to the other over a period of several hours and this phenomenon is known as the`nasal cycle'. Many studies have been conducted investigating this phenomenon but, as yet, a clear functional signi®cance for the nasal cycle in health and disease remains unde®ned.One problem with using the term`nasal cycle' is a lack of de®nition of what constitutes a`nasal cycle'. Earlier observational studies have reported this`cycle' to be present in I 80% of the population, 3,4 but more recent quantitative studies using numerical parameters have shown this ®gure to be much lower. 5,6 In these studies the authors quantitatively measured reciprocity (truly reciprocal changes in air¯ow between right and left passages) and periodicity (the regularity of changes in air¯ow occurring with time in each nasal passage). Their results indicate that true periodicity and reciprocity of nasal air¯ow exists in 21%À39% of the population. Therefore it appears that, on quantitative analyses, the term`nasal cycle' is a misnomer.The nasal epithelium has a very complex vasculature with a submucosal plexus of venous sinuses lining the nasal mucosa. These venous sinuses form erectile tissue that is well developed in the anterior part of the nasal septum and the inferior turbinate. 7 These submucosal cushions of venous sinuses expand and shrink, depending upon the degree of congestion, hence altering the calibre of the nasal passages and in¯uencing the nasal air¯ow. Whe...

The results demonstrate that pseudoephedrine is a safe and effective treatment for nasal congestion associated with URTI. The results from the laboratory study on day 1 demonstrate by both objective and subjective measures of nasal congestion that a single dose of 60 mg pseudoephedrine is superior to placebo treatment. Support for the decongestant efficacy of multiple doses of pseudoephedrine is provided by objective measures on day 3 and subjective measures made over three days, but not by the VAS scores on day 3.

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.

When taken at recommended doses, both paracetamol and the combination of paracetamol and caffeine are safe and effective treatments for primary dysmenorrhoea. Consistent with results from other acute pain states, caffeine acts as an analgesic adjuvant and enhances the efficacy of paracetamol.

The combination treatment provided a greater decongestant effect than either paracetamol or placebo and better pain relief than either pseudoephedrine or placebo. The additive effect of the combination was apparent for both single and multiple doses.