Animal and human calorimetry

List of principal symbols and abbreviations used Preface Introduction Historical Calorific equivalents Bomb calorimetry 3.1.1. Adiabatic bomb calorimetry 3.1.2. Ballistic bomb calorimetry The oxidation of foodstuffs and excreta 3.2.1. Carbohydrate 3.2.2. Fat 3.2.3. Protein 3.2.4. Incomplete oxidation 3.2.5. A shorter approach Review of published values 3.3.1. Calorific factors 3.3.2. Tables and equations for respiratory exchange measurements 3.3.3. Calculation from carbon-nitrogen balance 3.3.4. Metabolic water Summary and recommendations Indirect calorimeters Confinement systems 4.1.1. The Rowett Research Institute confinement respiration chambers a. Chambers and ventilation b. Pressure control c. Gas sampling, analysis and calculation 4.1.2. Pressure control by volume adjustment 4.1.3. Design theory IX xii 1 6 24 24 24 28 30 30 31 32 32 34 38 38 43 47 48 49 50 52 52 52 53 53 54 54 iv Contents 4.2 Closed-circuit 57 4.2.1. Small animal respirometers 57 a. Constant pressure systems 57 b. Constant volume systems 59 4.2.2. Large animal respiration chambers 62 4.2.3. Human respiration chambers 68 a. The Atwater and Benedict respiration chamber 68 4.2.4. Spirometers 71 a. Types of spirometer 72 b. The use of a spirometer 73 c. Spirometers as oxygen reservoirs 74 d. Spirometers for large animals 74 e. Calibration and errors 75 4.3 Total collection systems 76 4.3.1. Rigid collecting chambers 76 4.3.2. Bag systems 78 a. The Douglas bag 78 b. Other types of bag 82 4.4 Open-circuit systems 83 4.4.1. Portable systems (sample collection) 83 a. The Kofranyi-Michaelis (K-M) or Max Planck respirometer 83 b. The integrating motor pneumotachograph (IMP) 86 c. The Miser 88 d. The Oxylog 89 e. Tracheal cannulation techniques 90 4.4.2. Ventilated flow-through systems 93 a. Open-circuit chambers 94 b. Ventilated hoods 95 c. Masks and mouthpieces 96 d. Ventilation and air-conditioning 96 e. Gas mixing 97 f. Measurement of flowrate 98 g. Methods of gas analysis 98 h. A portable flow-through system - the metabolic rate monitor 99 4.5 Calculation methods 100 4.5.1. Steady-state conditions 102 a. Oxygen consumption from oxygen analysis and carbon dioxide absorption 102 b. Oxygen consumption when all respiratory gases are analysed 104 c. Carbon dioxide and methane production 105 d. Respiratory quotient 106 e. Metabolic rate 106 Contents 4.5.2. Dynamic conditions 4.5.3. Practical aspects 4.6 Other indirect systems 4.6.1. Labelled carbon 4.6.2. Doubly labelled water 4.6.3. Measurements that correlate with heat production 4.7 Summary 5 Direct calorimeters 5.1.1. The psychrometric chart 5.2 Types of direct calorimeters 5.2.1. Isothermal calorimeters 5.2.2. Heat-sink calorimeters 5.2.3. Convection calorimeters 5.2.4. Differential calorimeters 5.3 Gradient-layer calorimeters 5.3.1. The Hannah Research Institute large animal calorimeter a. The animal chamber b. Ventilation c. Air sampling d. Water cooling system e. Instrumentation f. Initial calibration g. Routine calibration and operation h. Performance 5.3.2. Gradient layers a. Basic sensitivity b. Spacing of measuring points c. Speed of response d. Resistance-thermometer layers e. Thermocouple layers f. Construction 5.3.3. Animal chambers a. Air leaks b. Heat leaks c. Illumination d. Animal-restraining structures 5.3.4. Ventilation a. Ventilation rate b. Platemeters c. Thermopiles d. Fans, heaters, ducting, etc. 5.3.5. Temperature control 108 111 112 113 114 117 118 120 120 122 122 126 127 127 128 128 129 133 134 136 137 138 139 140 141 142 142 143 144 146 152 153 153 154 154 155 155 155 156 161 161 163 vi Contents 5.4 Heat-sink calorimeters 5.4.1. The Dunn calorimeter a. The structure and ventilation b. Water circulation c. Estimation of heat losses d. Calibration 5.4.2. Other heat-sink calorimeters 5.4.3. Suit calorimeters 5.5 Convection calorimeters 5.6 Differential calorimeters 5.7 Evaporative heat loss 5.8 Other energy exchanges 5.9 Body heat storage 5.9.1. Mean skin temperature 5.9.2. Mean body temperature 6 Instrumentation 6.1 Instruments for basic measurements 6.1.1. Voltage 6.1.2. Temperature 6.1.3. Humidity a. Wet- and dry-bulb psychrometers b. Dewcells c. Peltier cooled mirrors 6.1.4. Pressure 6.2 Equipment for gas analysis 6.2.1. Chemical analysis a. Haldane analysis b. Scholander gas analyser 6.2.2. Physical analysers a. Oxygen electrodes or polarographic cells b. Paramagnetic oxygen analysers c. Infra-red gas analysers d. Mass spectrometers e. Thermal conductivity f. Fuel cells g. Gas chromatography 6.3 Instruments for the measurement of volume and flow 6.3.1. Measurement of volume a. Wet gasmeters b. Dry gasmeters c. Wright respirometer 6.3.2. Volume flowrate a. Turbine flowmeters b. Pneumotachograph c. Orifice flowmeters 165 165 165 166 167 168 168 169 172 175 176 180 181 181 183 184 185 185 185 187 187 188 188 190 190 191 191 194 196 197 200 209 214 215 216 217 218 219 219 222 225 226 226 226 227 Contents vii 6.3.3. Mass flowrate 227 a. Critical flowmeters 227 b. Thermal flowmeters 228 6.3.4. Variable-area flowmeters 230 6.4 Recorders and data loggers 232 6.5 Other instrumentation 234 6.5.1. Food supply 234 6.5.2. Collection of excreta 235 6.5.3. Safety aspects 237 7 Calibrations and standards 238 7.1 Standardisation of basic measurements 238 7.2 Calibration of gas analysers 238 7.2.1. Introduction 238 7.2.2. Sample conditioning 239 7.2.3. Calibration requirements 242 7.2.4. Standard gases 245 a. Zero gas 245 b. Dry fresh air 245 7.2.5. Calibration-gas mixtures 245 a. Static methods 246 b. Dynamic methods 246 c. Checking the composition of calibration mixtures 249 7.2.6. Linearity checks of oxygen analysers 251 a. By means of gas mixtures 251 b. By variation of pressure in the analytical cell 252 7.2.7. Calibration of pressure-sensitive oxygen analysers by the variable-pressure method 253 7.2.8. Calibration of carbon dioxide and methane analysers 259 a. Linearity checks 259 b. Routine calibration 261 7.3 Calibration of flowmeters 261 7.3.1. Soap-bubble flowmeters 262 7.3.2. Wet gasmeters 265 7.3.3. Critical-orifice flowmeters 268 7.3.4. Spirometers and gasometers 271 7.3.5. Gravimetric calibration 272 7.3.6. Dilution method 273 7.3.7. Calibration of flowmeters that measure pulsatile flow 273 7.4 Whole system checks 274 7.4.1. Recovery of heat 274 7.4.2. Recovery of carbon dioxide 275 7.4.3. Recovery of oxygen 276 a. Nitrogen injection 276 b. Steel-wool burners 278 viii Contents 1AA. Combined methods 280 a. Alcohol burners 280 b. Agreement between direct and indirect calorimetry 281 7.4.5. Calibration: the golden rules 282 7.5 Some additional problems encountered 282 8 Some complete open-circuit systems 284 8.1 Using a simple voltage recorder 284 8.2 Switched-range recorder and twin-channel oxygen analyser 287 8.3 Systems using divided reservoirs 287 8.4 The Leeds indirect flow-through calorimeters 289 8.4.1. The semi-automated human calorimeter 290 8.4.2. The semi-automated, multichamber small animal calorimeter 292 8.4.3. The computer-controlled multichamber small animal calorimeter 296 Appendices Al Calculation of calorific factors from elemental composition 299 A2 Solution of equations for heat production, and carbohydrate and fat metabolised 300 A3 Report of the Brouwer Committee (1965) 302 A4 Analysis of heat flow through gradient layers 305 1. The basic insulating layer 305 2. The metal foil covering the insulating layer 306 3. Reduced temperature gradient due to lateral heat flow in the thermocouple tape 306 4. Direct heat flow through the metal bridges 308 5. Heat flow at the edges of platemeters 308 A5 Some physical properties of materials used in constructing calorimeters 311 References 312 Index 335