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At least 19 recordsLinked to original sources
PubMed2001

Inspired gas temperature during mechanical ventilation: effects of environmental temperature and airway temperature probe position.

OBJECTIVES: To determine the inspired gas temperature during mechanical ventilation with: (i) five different humidicrib temperatures; (ii) two airway temperature probe (ATP) positions; and (iii) four ATP adaptors. METHODOLOGY: An observational study in the Neonatal Intensive Care Laboratory, Westmead Hospital. The inspired gas temperature was measured at the proximal end of the endotracheal tube (ETT) during conventional mechanical ventilation using a Tele-thermometer. Inspired gas temperature measurements were made with: (i) the humidicrib temperature set at 30.8. 32.9, 35.2, 36.2. or 37.2 degrees C; (ii) the ATP either (A) positioned inside the humidicrib at the distal end of the inspiratory tubing or (B) positioned outside the humidicrib 50 cm proximal to the ETT, with the inspired gas temperatures set at 36.5 and 39.0 degrees C, respectively; and (iii) the measurements repeated with four different ATP adaptors at each humidicrib temperature and each ATP position. RESULTS: With the ATP inside the humidicrib, there were no significant differences between set and actual inspired gas temperature. However, with the ATP outside the humidicrib, there were significant decreases in inspired gas temperature at each humidicrib temperature. For instance, with the ATP outside the humidicrib and set at 39.0 degrees C, the inspired gas temperature decreased to 34.7+/-0.2 degrees C at a humidicrib temperature of 30.8 degrees C and to 37.7+/-0.2 degrees C at a humidicrib temperature of 37.2 degrees C. The type of ATP adaptor also had a significant effect on inspired gas temperature. CONCLUSIONS: With the ATP placed outside the humidicrib and with variations of humidicrib temperature, infants are likely to have inspired gas temperatures that are significantly different to the desired temperature. Certain ATP adaptors cause these variations in inspired gas temperature to be more pronounced. Extreme care must be used to avoid suboptimal inspired gas temperatures with these environmental variations and the ATP positioned outside the humidicrib.

Environment, Controlled↗
PubMed2000

Tissue temperatures and lesion size during irrigated tip catheter radiofrequency ablation: an in vitro comparison of temperature-controlled irrigated tip ablation, power-controlled irrigated tip ablation, and standard temperature-controlled ablation.

The limited success rate of radiofrequency catheter ablation in patients with ventricular tachycardias related to structural heart disease may be increased by enlarging the lesion size. Irrigated tip catheter ablation is a new method for enlarging the size of the lesion. It was introduced in the power-controlled mode with high power and high infusion rate, and is associated with an increased risk of crater formation, which is related to high tissue temperatures. The present study explored the tissue temperatures during temperature-controlled irrigated tip ablation, comparing it with standard temperature-controlled ablation and power-controlled irrigated tip ablation. In vitro strips of porcine left ventricular myocardium were ablated. Temperature-controlled irrigated tip ablation at target temperatures 60 degrees C, 70 degrees C, and 80 degrees C with infusion of 1 mL saline/min were compared with standard temperature-controlled ablation at 70 degrees C and power-controlled irrigated tip ablation at 40 W, and infusion of 20 mL/min. Lesion size and tissue temperatures were significantly higher during all modes of irrigated tip ablation compared with standard temperature-controlled ablation (P < 0.05). Lesion volume correlated positively with tissue temperature (r = 0.87). The maximum recorded tissue temperature was always 1 mm from the ablation electrode and was 67 +/- 4 degrees C for standard ablation and 93 +/- 6 degrees C, 99 +/- 6 degrees C, and 115 +/- 13 degrees C for temperature-controlled irrigated tip ablation at 60 degrees C, 70 degrees C, and 80 degrees C, respectively, and 112 +/- 12 degrees C for power-controlled irrigated tip ablation, which for irrigated tip ablation was significantly higher than tip temperature (P < 0.0001). Crater formation only occurred at tissue temperatures > 100 degrees C. We conclude that irrigated tip catheter ablation increases lesion size and tissue temperatures compared with standard ablation in the temperature-controlled mode at the same or higher target temperatures and in the power-controlled mode. Furthermore, tissue temperature and delivered power are the best indicators of lesion volume during temperature-controlled ablation.

Animals↗
PubMed1997

Effects of environmental temperature and heat production due to food intake on abdominal temperature, shank skin temperature and respiration rate of broilers.

1. Eight broilers were used to determine the effects of environmental temperature and the increased heat production attributable to food intake on thermoregulatory physiological responses. Heat production, abdominal temperature, shank skin temperature and respiration rate were measured. 2. Heat production rose with increase in food intake and environmental temperature. Abdominal temperature, shank skin temperature and respiration rate also increased but, at 36 degrees C, there was no difference in respiration rate between the different rates of food intake after exposure for 1 h. Also, heat production decreased with exposure time when the birds were exposed to 28 degrees C and 32 degrees C, but increased at 36 degrees C ambient temperature. 3. Although the effect of the increased heat production on thermoregulatory physiological responses was not greater than that of environmental temperature, the increase in heat production enhanced the effect of ambient temperature on thermoregulatory physiological responses. However, with increasing heat production, the greatest response in shank skin temperature was at 28 degrees C, in respiration rate at 32 degrees C and in abdominal temperature at 36 degrees C. 4. These results suggest that, at high environmental temperatures, arranging feeding management to restrict the increase in heat production may alleviate the effect of environmental temperature.

Abdomen↗
PubMed1990

Milk temperature in the claw piece of the milking machine and mammary surface temperature are predictors of internal mammary temperature in goats.

Mammary internal and surface temperatures and milk temperature were correlated using five lactating goats. Internal mammary temperature was estimated using temperature-sensitive transmitters placed deep within the parenchyma of each mammary half. External mammary temperature was estimated using infrared thermography of four mammary skin sites: T1, teat end; T2, teat base; G1, about 20 mm above the teat base; and G2, about 20 mm ventral to the base of the gland deep to the thigh. The thermistor bead used for estimating milk temperature was placed in the claw piece where the short milk tube of the liner attaches. This placement minimized cooling effects of milk contact surfaces. The overall correlations of milk temperature with mammary temperatures ranged from 0.45 to 0.64. Correlations among the six paired values for the four external sites ranged from 0.76 to 0.92. Milk and surface temperatures, milking time, and milk weight were employed in various combinations as covariables; these were calculated within animal, within half. Milk temperature was the single most important predictor of internal mammary temperature in all models. Milk temperature alone or combined with covariables can be used to predict internal mammary temperature.

Animals↗
PubMed1994

Monitoring intrathecal temperature: does core temperature reflect intrathecal temperature during aortic surgery?

Paraplegia secondary to spinal cord ischemia is a common occurrence following proximal aortic surgery. Recent research has suggested that modest reductions in neuronal temperature (ie, a 2 to 5 degrees C reduction) may protect the central nervous system from ischemic injury, and several medical centers are now using modest whole body hypothermia in an attempt to protect the spinal cord during aortic surgery. However, to date, there are no reports to validate that reductions in core temperature will reduce intrathecal temperature during aortic surgery. In the present study, the correlation between core temperature, assessed with a pulmonary artery thermistor, and intrathecal temperature, assessed with a lumbar intrathecal thermocouple, were evaluated. Both devices were corrected for bias using a mercury thermometer standard. It was found that there was excellent correlation between pulmonary artery temperature and intrathecal temperature during all portions of the surgery (r = 0.948; P < 0.001). The regression line for the relationship was defined by the formula: intrathecal temperature = 0.98 x pulmonary artery temperature + 0.65. Furthermore, there was excellent correlation between bias-corrected intrathecal temperature and the temperature measured by commercially available, bias-uncorrected thermistors placed in the esophagus (r = 0.869; P < or = 0.001), urinary bladder (r = 0.873; P < 0.001), and pulmonary artery (r = 0.929; P < 0.001). Based on these data, it is concluded that there is a close correlation between intrathecal temperature and core temperatures during proximal aortic surgery, and commercially available thermistors provide sufficient accuracy to assess spinal cord cooling during attempts to protect the spinal cord from ischemic injury.

Aortic Aneurysm, Abdominal↗
PubMedDate not supplied

[The dependence of the temperature response to pyrogens on the ambient temperature and the initial body temperature].

The dependence of the temperature response to injection of Freund's complete adjuvant (FCA) containing killed and dried Mycobacterium butyricum on ambient temperature within 8-10, 14-16, 20-22, 26-28 degrees C ranges and initial body temperature was studied in experiments on rats, guinea pigs, and rabbits. The duration of the hyperthermic response was maximal at an ambient temperature 14-16 degrees C, and its dynamics can be divided in 2 phases, initial febrile and subsequent subfebrile. An increase in rectal temperature after application of the agent was the higher the lower was its initial value and vice versa. The hyperthermic response to FCA did not occur at 8-10 degrees C.

Analysis of Variance↗
PubMed1977

Effect of temperature and temperature shifts on growth and branching of a wild type and a temperature sensitive colonial mutant (Cot 1) of Neurospora crassa.

Growth of a temperature sensitive colonial mutant (cot 1) of Neurospora crassa was compared with a wild type strain. The hyphal growth unit (the ratio between mycelial length and number of branches) of the wild type was not appreciably altered by temperature and there was a direct relationship between the specific growth rate (alpha) of these mycelia and their mean hyphal extension rate (E). The specific growth rate of cot 1 increased by about the same relative amount as the wild type between 15 degrees and 30 degrees C. Cot 1 grew and branched normally at 15 degrees and 25 degrees C but at 30 degrees C the hyphal growth unit and mean hyphal extension rate of the mutant mycelia were reduced. Thus, between 15-30 degrees C the ratio, E/alpha was constant for the wild type but not for cot 1. The effect of temperature and temperature shifts on extension zone length (2), extension zone expansion time (2t) and branching of leading hyphae of mature colonies were also studied. It is suggested that branching is governed by a mechanism which regulates the linear growth rate of hyphae; the cot 1 mutation may have a direct effect on wall extension or affect linear growth rate indirectly due to an influence on the transport of precursors to the tip.

Mutation↗
PubMed2002

[The temperature and temperature gradient distribution in the thermophysical model of the rabbit body subjected internal and external changes of temperature].

In a laboratory heat-physical model of the rabbit reflecting basic heat-physical parameters of animal body (weight, heat absorption and heat production, size of a relative surface, capacity heat-production etc.), the changes of radial distribution of temperature and size of a cross superficial temperature gradient of the body were investigated with various parities (ratio) of environmental temperature and size of capacity heat production imitated by an electrical heater. Superficial layer of the body dependent from capacity heat production and environmental temperature can serve for definition of general heat content changes in the body for maintaining its thermal balance within the environment.

Animals↗
PubMed1979

Comparative studies of wild-type and cold-mutant (temperature-sensitive) influenza viruses: independent segregation of temperature-sensitivity of virus replication from temperature-sensitivity of virion transcriptase activity during recombination of mutant A/Ann Arbor/6/60 with wild-type H3N2 strains.

RNA 1 (see end of Summary) of a cold-adapted and temperature-sensitive (ts) influenza virus mutant A/Ann Arbor/6/60 has a different mobility from RNA 1 of wild-type (wt) A/Ann Arbor/6/60 when subjected to electrophoresis through acrylamide/agarose gels in the absence of denaturing agents. Detection of this lesion in RNA 1 of the mutant virus was dependent on the temperature of the gel during electrophoresis. Because RNA 1 is believed to code for a protein involved in virus-specific RNA synthesis we compared phenotypes of virion transcriptases in the wt and mutant viruses. The enzyme of the mutant virus was found to be about 40% less active at 40 degrees C than the enzyme of the wt virus when related to their activities at 31 degrees C. Two cold-adapted ts recombinants which derive their RNA 1 from the mutant A/Ann Arbor/6/60 have virion transcriptases with a phenotype similar to that of their mutant parent. Three different cold-adapted ts recombinants, however, which also derive their RNA 1 from the mutant A/Ann Arbor/6/60, have virion transcriptases with a phenotype similar to that of wt virus. We conclude, therefore, that the conditional-lethal ts property of A/Ann Arbor/6/60 mutant and its recombinants is independent of the phenotypic marker observed for the A/Ann Arbor/6/60 mutant virion transcriptase, and that the lesion in RNA 1 of the mutant may also be unrelated to the observed difference between virion transcriptases of the mutant and wt A/Ann Arbor/6/60 viruses. The phenotypes of the virion transcriptases in recombinants did, however, correlate with the derivation of their RNA 2. This suggests that the increased temperature-sensitivity of virion transcriptase of the A/Ann Arbor/6/60 mutant is caused by either (1) a lesion (not necessarily conditionally lethal) that occurred in its RNA 2 during the course of cold-adaptation, or (2) a lesion in another gene whose product is a component of the virion transcriptase complex, but which lesion is only expressed phenotypically when there is a synergistic interaction in the transcriptase complex with the product of A/Ann Arbor/6/60 rna 2.

Cold Temperature↗
PubMed1986

Developmental temperature and life span in Drosophila melanogaster. I. Constant developmental temperature: evidence for physiological adaptation in a wide temperature range.

The concept of an inverse relationship between life span of adult Drosophila and their developmental temperature is probably the result of an unwarranted generalization. Rather, in a wild-type laboratory strain the present study revealed a plateau phase in this relationship between 16 and 29 degrees C in which life span of both male and female flies was roughly independent of developmental temperature. Below and above this range, life span dropped drastically, development being impossible below 12 and above 32.5 degrees C. Simultaneous study of growth characteristics showed that the plateau phase corresponded to a 'physiological' range of developmental temperature, development being apparently disturbed outside that range. Within that physiological range, the growth rate of the flies varied varied 2-fold, while life span remained constant corroborating our previous conclusion that growth rate per se does not determine life span.

Adaptation, Physiological↗
PubMed1999

Investigation of combwax of honeybees with high-temperature gas chromatography and high-temperature gas chromatography-chemical ionization mass spectrometry. I. High-temperature gas chromatography.

The combwaxes of the honeybee species Apis mellifera, Apis cerana, Apis dorsata, Apis laboriosa, Apis florea and Apis andreniformis have been examined by high-temperature gas chromatography. Combwax consists of a complex mixture of homologous neutral lipids. These compounds containing up to 64 carbons were chromatographed intact on a 10 m x 0.2 mm high-temperature stable SOP-50-PFD (50%-diphenyl/50%-1H,1H,2H,2H-perfluorodecylmethylpolysiloxane)-co ated Duran glass capillary column. The use of this stationary phase results in lower retention values and, at last, in lower thermal stress of the analytes. In order to minimize the discrimination effect due to adsorption and/or degradation, a two-step derivatization was performed resulting in the formation of tert.-butyldimethylsilyl esters of the long chain fatty acids and trimethylsilyl ethers of complex hydroxyesters, respectively. The derivatization procedure was optimized using a modification of the extended Donike test. In addition this test allows the quantification of the thermal stability of the derivatives performed. The derivatization procedure was applied for combwax analysis. More than 80 compounds were separated and their peak areas semiquantitatively exploited.

Animals↗
PubMed1993

Further studies of 31 temperature-sensitive mutants of mouse cytomegalovirus: thermal stability, replication and analysis of temperature-sensitive functions by temperature shift.

A study of 31 temperature-sensitive mutants of mouse cytomegalovirus has indicated that two mutants (tsm1, tsm31) may be defective in immediate-early/early functions, two (tsm2, tsm3) may be defective in early functions and six (tsm9, tsm18, tsm22, tsm23, tsm28, tsm30) may be defective in early/late functions while the remainder are late function-defective mutants as determined by temperature-shift experiments. Three mutants (tsm1, tsm2, tsm3) were more thermostable than wild-type virus while three (tsm16, tsm26, tsm28) were more thermolabile; the remainder were similar in their thermostability to wild-type virus.

Muromegalovirus↗
PubMed1979

Survival in subzero temperatures: two field experiments on temperature estimation and "snowhole" (survival hole) temperatures.

Two field experiments in a subarctic environment are described. Individuals consistently underestimated the degree of cold, because visual cues dominated sensory skin receptors in the subjective estimation of temperature. In snowholes (survival holes) temperatures rose 20 degrees C within 30 minutes of occupancy, but stabilized at freezing point. Implications for travel and survival in a subzero environment are described.

Cold Climate↗
PubMed2000

Investigation of combwax of honeybees with high-temperature gas chromatography and high-temperature gas chromatography-chemical ionization mass spectrometry. II: High-temperature gas chromatography-chemical ionization mass spectrometry.

Crude combwax of six various honey bee species have been analyzed by high-temperature gas chromatography (HTGC)-chemical ionization mass spectrometry after a two-step silylation procedure. An optimized chromatographic procedure, described previously, enables the separation of high-molecular mass lipid compounds resulting in a characteristic fingerprint of the combwaxes of different honeybee species. The coupling of HTGC to mass spectrometry requires appropriate instrumentation in order to achieve sufficient sensitivity at high elution temperatures and avoid loss of chromatographic resolution. Chemical ionization was carried out using methane as reagent gas in order to determine the molecular mass of the individual compounds by means of abundant quasi molecular ions. To confirm the presence of unsaturated wax esters, ammonia was used as reagent gas. More than 80 lipid constituents were separated and characterized by their mass spectra. Representative chemical ionization mass spectra of individual compounds are presented. Both, HTGC-flame ionization detection data and the results of the HTGC-mass spectrometric investigations enabled a rapid profiling of the individual classes of compounds in crude combwaxes.

Animals↗
PubMed1992

Hoof and distal limb surface temperature in the normal pony under constant and changing ambient temperatures.

Forelimb surface temperatures were continuously monitored in four clinically normal ponies exposed to: (i) constant ambient temperature; (ii) a biphasic change in ambient temperature; and (iii) an incremental increase in ambient temperature. Limb surface temperatures were recorded at the hoof, metacarpus and forearm, and rectal temperature was also measured. Under constant ambient temperature, limb surface temperatures remained relatively constant. A pyrexic episode occurred in one pony under constant ambient temperature conditions and was characterised by an onset phase in which rectal temperature gradually increased while limb surface temperatures concurrently decreased; a plateau phase in which rectal temperature was elevated but essentially constant although limb surface temperatures rose dramatically; and a febrilytic phase in which limb surface temperatures remained elevated while rectal temperature gradually decreased. A biphasic change in ambient temperature produced corresponding changes in limb surface temperature, but limb surface temperatures were less stable at the lower ambient temperatures. Surface temperature responses to incremental increases in ambient temperature were dependent on the baseline ambient temperature (before increase), and dramatic, spontaneous increases in limb surface temperatures were observed. Rectal temperatures in the normal animals remained relatively constant under all three ambient temperature regimens. It was concluded that clinical interpretation of limb surface temperatures in ponies required an awareness of ambient temperature conditions. For evaluation of vasodilator agents, constant ambient temperatures of at least less than 18 degrees C are suggested, and constant ambient temperatures exceeding 20 degrees C are recommended for the evaluation of vasoconstrictor agents.

Animals↗
PubMed2003

[Bladder temperature versus tympanic membrane and forehead skin temperature].

INTRODUCTION: The purpose of the study was to compare three different methods of assessing the core temperature: by measuring the bladder temperature, the tympanic temperature, (Braun Thermoscan 3000) and the forehead skin temperature (Philips SensorTouch). Measuring of the bladder temperature and the tympanic temperature are wellknown methods whereas measuring of the forehead skin temperature by the use of Sensor Touch is a fairly new method by which the temperature at the warmest area of the forehead is measured. MATERIAL AND METHODS: Forty-two randomly chosen adult patients who all had a bladder catheter with a thermometer and a normal urine output. The patients were admitted to an intensive care unit and none were intubated nasally. Otoscopy was performed prior to temperature measurement. The temperatures were measured almost simultaneously. At the same time a white blood cell count and the C-reactive-protein value was recorded. RESULTS: There was a good linear coherence between the bladder temperature and the tympanic temperature (r = 0.97). The linear coherence between the bladder temperature and the forehead skin temperature was poor (r = 0.59). We found a mean deviation of 0.07 degree C and a standard deviation of 0.3 degree C of the difference between the bladder temperature and the tympanic temperature (p = 0.19). The mean of the difference between the bladder temperature and the forehead skin temperature was 0.5 degree C and a standard deviation of 0.8 degree C (p = 0.0003). Furthermore the forehead skin thermometer was not able to measure temperatures < 35.0 degrees C. We found no statistically significant coherence between the core temperature and the white blood cell count or C-reactive-protein. DISCUSSION: Tympanic temperature was well coherent with bladder temperature--forehead skin temperature was poorly coherent with bladder temperature. By evaluating the core temperature in intensive care patients the tympanic temperature is a reliable alternative to the bladder temperature.

Adult↗