Cardiovascular Research, 1976, 10, 69 1-696.
Cardiovascular responses in man to a stream of cold air' HAY WARD^, w . F . H O L M E S ~ ,and B . A . G O O D E N From the Department of Physiology and Pharmacology, University Hospital and Medical School, Clifton Boulevard, Nottingliatn
J. M.
The familiar problem of the precipitation of (-14°C) but six developed angina pectoris. The angina pectoris in cardiac patients on exposure aetiology of this phenomenon therefore remains to cold air or wind has recently attracted re- obscure. newed interest (British Medical Journal, 1974). Normal men breathing cold air (-16°C) An ice-cold stimulus applied to the forehead through the mouth have demonstrated an was observed by Neil1 et a1 (1974) to increase increase in stroke volume without a change in myocardial oxygen consumption and coronary heart rate or peripheral resistance (Leon er al, blood flow in patients with and without evi- 1970). The application of a plastic bag filled dence of heart disease. They attributed these with ice-chips to the forehead has been shown changes to the concomitant increase in systemic to evoke reflex peripheral vasoconstriction in arterial blood pressure. Subsequently, Hatten- the hand (Kontos and Wasserman, 1969) and hauer and Neil1 ( I 975) reported that coronary forearm (Abboud and Eckstein, 1966). disease patients who breathed cold air (-20°C) Since a variety of cold stresses has been used through the nose did not exhibit significant in these studies, their relevance and relationship changes in myocardial oxygen consumption to the problem of angina pectoris evoked by a and that the accompanying systemic changes cold wind is difficult to assess. None of the cold were minor. However, angina pectoris was stimuli mentioned closely resembles a cold wind evoked in four of 17 patients with coronary blowing on the face with the associated breathing disease. Similarly Sorensen (1 966) found no of this air. change in blood pressure, pulse or arterial The aim of the present study was to examine oxygen saturation in 15 coronary disease the cardiovascular responses of 12 healthy patients during mouth-breathing of cold air adults to a stream of cold air directed at the 'Reprint requests to B.A.G.. Department of Physiology and Pharmafront of the face, at the side of the face and at cology, University Hospital and Medical School, Clifton Boulevard, the abdomen separately. The subjects were Nortingharn NG7 2UH. Work carried out in part fulfilment of the requirements for the free to breathe this air through the nose. Heart Honours Degree of Bachelor of Medical Sciences, University o f rate, brachial arterial blood pressure, and Nottingham.
Downloaded from by guest on April 10, 2016
A U T H O R S ' S Y N O P S I S Cardiovascular responses to a stream of cold air (0-10°C) directed towards the face and abdomen separately were examined in 12 human subjects. Cold air directed at the side of the face produced a 36*6% increase in forearm vascular resistance and 22*4% reduction in blood flow. Cold air on the abdomen did not produce a significant change in vascular resistance. The results are discussed in relation to angina pectoris evoked by cold wind.
692 Hayward, Holmes, and Goodeti forearm blood flow were measured throughout these procedures. Forearm vascular resistance was calculated from the mean blood pressure and mean blood flow.
Methods The subjects in this study were 12 healthy adult volunteers, six males and six females, aged between 19 and 30 years. The room air temperature was maintained at approximately 25°C. During each experiment the following measurements were made.
Heart rate The electrocardiogram was recorded from two chest electrodes placed to approximate standard chest lead V,. The output was amplified and directed to one channel of an Oscillograph U V recorder (SE 2012). The other measurements were also recorded on the remaining channels.
Blood pressure Brachial arterial blood pressure was measured in the left arm by means of an automatic ultrasonic blood pressure monitor (Arteriosonde 1217) every 30 seconds. Hockberg and Salmon (1 97 1) compared this device (Arteriosonde) with the Korotkoff sounds method of measuring arterial blood pressure in 244 patients. The mean differences between the methods were 0.067 kPa and 0.013 kPa (0.5 mmHg and 0.1 mmHg) for systolic and diastolic pressure, respectively. Chest movements Movements of the chest wall were monitored by a stethograph consisting of a mercury-in-rubber strain gauge mounted across the chest at the level of the xiphisternum. Temperature of the air-stream A bead thermistor was attached at a distance of approximately 5 cm beyond the air delivery nozzle. Air stream device Room air was drawn into a vacuum cleaner which
Procedures Each experiment began with the subject seated upright on a couch. Male subjects were naked from the waist upwards and female subjects wore a bikini top. After application of the ECG electrodes, stethograph, forearm strain gauge, and blood pressure monitor the subject rested for 5 min before the experimental procedures began. There were three main procedures, each divided into a control period of 3 min, 1 min of air blown onto the target skin, and I min of recovery. The sequence of the procedures was varied from subject to subject, and the subjects were not aware of the planned order of the procedures. There were three main procedures. Cold air on the front o j t h e face The air stream was directed straight at the centre of the face. Cold air on the side of the face The air stream was directed at the left cheek. Cold air on the abdomen The air stream was directed at the umbilicus.
+
Cold air on the face mouth-breathing room air An additional procedure was performed in four subjects who produced a vasoconstrictor response to both the cold air on the front and side of the face procedures. Whilst exposed to cold air on the front of the face for 60 s, the subject breathed room air (25°C) through a mouth piece. Analysis of
data Mean arterial blood pressure was calculated from the formula: f (systolic pressure) + 2 (diastolic pressure). Vascular resistance was calculated by dividing the mean blood pressure by the mean forearm blood flow recorded in the same time interval.
Downloaded from by guest on April 10, 2016
Forearm blood flow Blood flow was measured in the right forearm every I5 s by venous occlusion plethysmography using a mercury-in-rubber strain gauge (Whitney, 1953). In three additional experiments hand blood flow was measured in place of forearm blood flow using a water-filled plethysmograph (Greenfield, 1954).
acted as a pump for the system. The air was blown through a canister of anhydrous calcium chloride to dry it and was then cooled by being passed through a coil of copper tubing immersed in a vacuum flask containing a mixture of solid carbon dioxide and methanol. The temperature of the cooled air at the delivery funnel was between 0" and 10°C. The flow of air through the delivery tube measured by a rotameter was approximately 56 litreimin. The air stream was directed manually by positioning the air funnel about 6 cm from the target skin.
693
responses t o a stream of'cold air
Cardiovascular
Control values were calculated from the mean of the data obtained during the first 2 min of the 3 min control period. This precaution was taken in a n attempt to eliminate any anticipatory response immediately before the test procedure. The mean heart rate and blood flow levels during the first and second 30s periods of each 1 min procedure were calculated by averaging the values obtained during the respective intervals. The paired t test was used to determine the statistical significance of changes in the measurements from control to test procedure levels. A P value of less than 0.05 was considered to be significant.
Results
Cold air on the abdomen Blowing cold air onto the abdomen did not produce statistically significant changes in forearm blood flow or vascular resistance. Seven subjects demonstrated a reduction in vascular resistance (mean -14%; Fig. 2). Only
g n Downloaded from by guest on April 10, 2016
Cold air on the side of the face A stream of cold air directed at the side of the face produced significant changes in heart rate, forearm blood flow, and forearm vascular resistance during both the first and second 30 s of the procedure. The heart rate decreased by an average of 9* 1 % (mean+SE) for the whole minute (P
Cardiovascular responses in man to a stream of cold air' HAY WARD^, w . F . H O L M E S ~ ,and B . A . G O O D E N From the Department of Physiology and Pharmacology, University Hospital and Medical School, Clifton Boulevard, Nottingliatn
J. M.
The familiar problem of the precipitation of (-14°C) but six developed angina pectoris. The angina pectoris in cardiac patients on exposure aetiology of this phenomenon therefore remains to cold air or wind has recently attracted re- obscure. newed interest (British Medical Journal, 1974). Normal men breathing cold air (-16°C) An ice-cold stimulus applied to the forehead through the mouth have demonstrated an was observed by Neil1 et a1 (1974) to increase increase in stroke volume without a change in myocardial oxygen consumption and coronary heart rate or peripheral resistance (Leon er al, blood flow in patients with and without evi- 1970). The application of a plastic bag filled dence of heart disease. They attributed these with ice-chips to the forehead has been shown changes to the concomitant increase in systemic to evoke reflex peripheral vasoconstriction in arterial blood pressure. Subsequently, Hatten- the hand (Kontos and Wasserman, 1969) and hauer and Neil1 ( I 975) reported that coronary forearm (Abboud and Eckstein, 1966). disease patients who breathed cold air (-20°C) Since a variety of cold stresses has been used through the nose did not exhibit significant in these studies, their relevance and relationship changes in myocardial oxygen consumption to the problem of angina pectoris evoked by a and that the accompanying systemic changes cold wind is difficult to assess. None of the cold were minor. However, angina pectoris was stimuli mentioned closely resembles a cold wind evoked in four of 17 patients with coronary blowing on the face with the associated breathing disease. Similarly Sorensen (1 966) found no of this air. change in blood pressure, pulse or arterial The aim of the present study was to examine oxygen saturation in 15 coronary disease the cardiovascular responses of 12 healthy patients during mouth-breathing of cold air adults to a stream of cold air directed at the 'Reprint requests to B.A.G.. Department of Physiology and Pharmafront of the face, at the side of the face and at cology, University Hospital and Medical School, Clifton Boulevard, the abdomen separately. The subjects were Nortingharn NG7 2UH. Work carried out in part fulfilment of the requirements for the free to breathe this air through the nose. Heart Honours Degree of Bachelor of Medical Sciences, University o f rate, brachial arterial blood pressure, and Nottingham.
Downloaded from by guest on April 10, 2016
A U T H O R S ' S Y N O P S I S Cardiovascular responses to a stream of cold air (0-10°C) directed towards the face and abdomen separately were examined in 12 human subjects. Cold air directed at the side of the face produced a 36*6% increase in forearm vascular resistance and 22*4% reduction in blood flow. Cold air on the abdomen did not produce a significant change in vascular resistance. The results are discussed in relation to angina pectoris evoked by cold wind.
692 Hayward, Holmes, and Goodeti forearm blood flow were measured throughout these procedures. Forearm vascular resistance was calculated from the mean blood pressure and mean blood flow.
Methods The subjects in this study were 12 healthy adult volunteers, six males and six females, aged between 19 and 30 years. The room air temperature was maintained at approximately 25°C. During each experiment the following measurements were made.
Heart rate The electrocardiogram was recorded from two chest electrodes placed to approximate standard chest lead V,. The output was amplified and directed to one channel of an Oscillograph U V recorder (SE 2012). The other measurements were also recorded on the remaining channels.
Blood pressure Brachial arterial blood pressure was measured in the left arm by means of an automatic ultrasonic blood pressure monitor (Arteriosonde 1217) every 30 seconds. Hockberg and Salmon (1 97 1) compared this device (Arteriosonde) with the Korotkoff sounds method of measuring arterial blood pressure in 244 patients. The mean differences between the methods were 0.067 kPa and 0.013 kPa (0.5 mmHg and 0.1 mmHg) for systolic and diastolic pressure, respectively. Chest movements Movements of the chest wall were monitored by a stethograph consisting of a mercury-in-rubber strain gauge mounted across the chest at the level of the xiphisternum. Temperature of the air-stream A bead thermistor was attached at a distance of approximately 5 cm beyond the air delivery nozzle. Air stream device Room air was drawn into a vacuum cleaner which
Procedures Each experiment began with the subject seated upright on a couch. Male subjects were naked from the waist upwards and female subjects wore a bikini top. After application of the ECG electrodes, stethograph, forearm strain gauge, and blood pressure monitor the subject rested for 5 min before the experimental procedures began. There were three main procedures, each divided into a control period of 3 min, 1 min of air blown onto the target skin, and I min of recovery. The sequence of the procedures was varied from subject to subject, and the subjects were not aware of the planned order of the procedures. There were three main procedures. Cold air on the front o j t h e face The air stream was directed straight at the centre of the face. Cold air on the side of the face The air stream was directed at the left cheek. Cold air on the abdomen The air stream was directed at the umbilicus.
+
Cold air on the face mouth-breathing room air An additional procedure was performed in four subjects who produced a vasoconstrictor response to both the cold air on the front and side of the face procedures. Whilst exposed to cold air on the front of the face for 60 s, the subject breathed room air (25°C) through a mouth piece. Analysis of
data Mean arterial blood pressure was calculated from the formula: f (systolic pressure) + 2 (diastolic pressure). Vascular resistance was calculated by dividing the mean blood pressure by the mean forearm blood flow recorded in the same time interval.
Downloaded from by guest on April 10, 2016
Forearm blood flow Blood flow was measured in the right forearm every I5 s by venous occlusion plethysmography using a mercury-in-rubber strain gauge (Whitney, 1953). In three additional experiments hand blood flow was measured in place of forearm blood flow using a water-filled plethysmograph (Greenfield, 1954).
acted as a pump for the system. The air was blown through a canister of anhydrous calcium chloride to dry it and was then cooled by being passed through a coil of copper tubing immersed in a vacuum flask containing a mixture of solid carbon dioxide and methanol. The temperature of the cooled air at the delivery funnel was between 0" and 10°C. The flow of air through the delivery tube measured by a rotameter was approximately 56 litreimin. The air stream was directed manually by positioning the air funnel about 6 cm from the target skin.
693
responses t o a stream of'cold air
Cardiovascular
Control values were calculated from the mean of the data obtained during the first 2 min of the 3 min control period. This precaution was taken in a n attempt to eliminate any anticipatory response immediately before the test procedure. The mean heart rate and blood flow levels during the first and second 30s periods of each 1 min procedure were calculated by averaging the values obtained during the respective intervals. The paired t test was used to determine the statistical significance of changes in the measurements from control to test procedure levels. A P value of less than 0.05 was considered to be significant.
Results
Cold air on the abdomen Blowing cold air onto the abdomen did not produce statistically significant changes in forearm blood flow or vascular resistance. Seven subjects demonstrated a reduction in vascular resistance (mean -14%; Fig. 2). Only
g n Downloaded from by guest on April 10, 2016
Cold air on the side of the face A stream of cold air directed at the side of the face produced significant changes in heart rate, forearm blood flow, and forearm vascular resistance during both the first and second 30 s of the procedure. The heart rate decreased by an average of 9* 1 % (mean+SE) for the whole minute (P
