REACTIONS OF THE NASAL CAVITY AND POSTNASAL SPACE TO CHILLING OF THE BODY SURFACE : I. VASOMOTOR REACTIONS

Common cold

The common cold is a unique human disease, as it is arguably the most common disease and because of the large number of respiratory viruses causing colds it is one of the most complex of human diseases. This review discusses the respiratory viruses and notes that all these viruses may cause the illness complex recognised as the common cold. The common cold is discussed as part of the "iceberg concept" of disease which ranges from asymptomatic infection to severe illness and death. The factors influencing the incidence of colds are discussed: crowding and sociability, stress, smoking and alcohol, immune status, sex, age, sleep, season, chilling, nutrition and exercise. The mechanism of symptoms related to the innate immune response is explained and symptomatic treatments are tabulated. Morbidity associated with common cold is discussed and possible vaccines.

Etiological factors in broncho-pneumonia amongst infants in London

1. In the period 1923–39, more than one-fifth of all deaths in the age group 0-2 years in the Administrative County of London are recorded as having been caused by bronchitis or broncho-pneumonia. It is very unlikely that the returns have been exaggerated by more than 10–15% through the inclusion of deaths from secondary broncho-pneumonia following measles, whooping cough or influenza. In the 8 years in which measles epidemics occurred, the peak of the measles mortality was from 2 to 17 weeks after, and never before, that of the mortality from broncho-pneumonia.

2. The winter rise in mortality from broncho-pneumonia is not associated with any comparable increase in the carrier rates for pneumococci and haemolytic streptococci.

3. The broncho-pneumonia mortality of infants in the Metropolitan Boroughs is strongly correlated with sub-standard housing incidence, social index and percentage below the poverty line. The relatively small value found for the coefficient of regression between broncho-pneumonia mortality and sub-standard housing may be due to the less rigorous winter temperatures occurring in the more overcrowded central areas.

4. Low external temperature appears to be the most important predisposing cause of fatal broncho-pneumonia in infants; their weekly death-rate from this disease in mid-winter is about seven times that in the late summer. This great seasonal fluctuation in mortality is also found for persons over 55 years in the Administrative County, and for persons of all ages in both the urban and rural districts of the Home Counties.

5. The weekly mortalities of infants from broncho-pneumonia in the Administrative County are most strongly correlated with low temperatures 2 weeks earlier. The two variables are so associated that the mortality rises sharply when the mean temperature of the coldest day of the week falls below 40° F. There is no indication that low temperatures in the spring are associated with higher death-rates from broncho-pneumonia than the same temperatures in the autumn, so that the data provide no support for the supposition that susceptibility increases during the winter in consequence of the progressive depletion in the body of protective nutrient substances.

6. Possible measures to reduce the mortality of infants from broncho-pneumonia are discussed.

The effect of ice packs upon nasal mucosal blood flow

The effect on nasal mucosal blood flow of ice packs on the forehead and ice packs within the mouth was investigated in 16 healthy subjects. The laser Doppler flowmeter was used to record changes in blood flow to the inferior turbinate, as measured by change in the flux. Ice packs within the mouth produced a significant decrease in nasal mucosal blood flow (p less than 0.05). The average fall was 23% (SEM 5.9) compared with the control measurements. No significant change was recorded following the application of ice packs to the forehead. The results of this study question the scientific rationale behind the use of forehead ice packs in clinical practice.

Influence of environmental temperature on human nasal mucosa

Nasal mucosal blood flow and nasal patency were studied in seven healthy subjects in order to evaluate normal physiological reactions to cold and heat. Blood flow was measured by means of the 133Xe washout method, and nasal patency was determined by measuring maximal nasal expiratory air flow. In comparison with the results at room temperature (23 degrees C), there was a decreased blood flow and a decreased nasal patency after 20 minutes of exposure to cold (6 degrees C). After exposure to heat (40 degrees C), an unaltered blood flow and an increased nasal patency were registered. The results suggest that nasal patency is important for the conditioning of air and support the hypothesis that changes in nasal mucosal blood flow is engaged in body temperature regulation.

The laser Doppler flowmeter for measuring microcirculation in human nasal mucosa

A new technique, based on the laser doppler principle, for measuring nasal mucosal microcirculation in humans, is presented. With this technique the relation between the blood flow and the temperature of the nasal mucosa was evaluated in healthy subjects exposed to peripheral cold stimulus. A decrease in blood flow and in mucosal temperature was found in all subjects when the feet were exposed to cold water for 5 min. The decrease in blood flow occurred almost momentarily and was restored to normal within the 5 min of exposure, while the drop in mucosal temperature was more gradual and persisted for a longer time. The implication of this study is that the laser doppler flowmeter seems to be a useful tool for estimation of changes in nasal mucosal microcirculation.

Blood flow with 133Xe in human nasal mucosa in relation to age, sex and body position

The blood flow in human nasal mucosa was determined using the 133Xe wash-out method in 80 subjects of both sexes. The blood flow was estimated to (mean +/- SD) 33 +/- 10 ml . min-1 . (100 g)-1. A correlation was found between decreasing blood flow and increasing age. There was no difference between the sexes. The blood flow was significantly decreased in the sitting position compared to the supine position. In repeated determinations, the first recording did not disturb the second one 15 to 60 min later. The coefficient of variation was estimated to 22%. The investigation gives reference values for further studies of the blood flow in the human nasal mucosa.

Effects of breathing warm humidified air on bronchoconstriction induced by body cooling and by inhalation of methacholine

The effect of breathing warm humidified air upon bronchoconstriction induced with body cooling or inhalation of methacholine was studied in two groups of eight asthmatic subjects. One group had the body cooled using one-minute exposures, first to a cold shower at 15 degrees C and then to a current of wind. The other group received methacholine by inhalation until a decrease of 20 percent or more occurred in the forced expiratory volume in one second. Both groups of asthmatic subjects were tested when breathing room air and warm humidified air. Pulmonary functions were assessed before and after cooling of the body and during inhalation of methacholine. Breathing warm humidified air substantially reduced bronchoconstriction induced by body cooling, but not that induced by inhalation of methacholine. Thus, bronchoconstriction induced by cooling of the body appears to be related to cooling of the airways, which may be compensated by breathing warm humidified air.