Digital infrared thermographic imaging for remote assessment of traumatic injury

2011 ◽  
Vol 111 (6) ◽  
pp. 1813-1818 ◽  
Author(s):  
William H. Cooke ◽  
Gilbert Moralez ◽  
Chelsea R. Barrera ◽  
Paul Cox
Keyword(s):  
Stroke Volume ◽  
Respiratory Rate ◽  
Skin Temperature ◽  
Lower Body Negative Pressure ◽  
Traumatic Injury ◽  
Sign Detection ◽  
Thermographic Imaging ◽  
Thermographic Camera ◽  
Remote Assessment ◽  
Injured Patients

The purpose of this study was to test the hypotheses that digital infrared thermographic imaging (DITI) during simulated uncontrolled hemorrhage will reveal 1) respiratory rate and 2) changes of skin temperature that track reductions of stroke volume. In 45 healthy volunteers (25 men and 20 women), we recorded the ECG, finger photoplethysmographic arterial pressure, respiratory rate (pneumobelt and DITI of the nose), cardiac output (inert rebreathing), and skin temperature of the forehead during lower body negative pressure (LBNP) at three continuous decompression rates; slow (−3 mmHg/min), medium (−6 mmHg/min), and fast (−12 mmHg/min) to an ending pressure of −60 mmHg. Respiratory rates calculated from the pneumobelt (14.7 ± 0.9 breaths/min) and DITI (14.9 ± 1.2 breaths/min) were not different ( P = 0.21). LBNP induced an average stroke volume reduction of 1.3 ml/mmHg regardless of decompression speed. Maximal reductions of stroke volume and forehead temperature were −100 ± 12 ml and −0.32 ± 0.12°C (slow), −86 ± 12 ml and −0.74 ± 0.27°C (medium), and −78 ± 5 ml and −0.17 ± 0.02°C (fast). Changes of forehead temperature as a function of changes of stroke volume were best described by a quadratic fit to the data (slow R2 = 0.95; medium R2 = 0.89; and fast R2 = 0.99).Our results suggest that a thermographic camera may prove useful for the remote assessment of traumatically injured patients. Life sign detection may be determined by verifying respiratory rate. Determining the magnitude and rate of hemorrhage may also be possible based on future algorithms derived from associations between skin temperature and stroke volume.

scholarly journals Evidence for unloading arterial baroreceptors during low levels of lower body negative pressure in humans

2009 ◽  
Vol 296 (2) ◽  
pp. H480-H488 ◽  
Author(s):  
Qi Fu ◽  
Shigeki Shibata ◽  
Jeffrey L. Hastings ◽  
Anand Prasad ◽  
M. Dean Palmer ◽  
...  
Keyword(s):  
Steady State ◽  
Stroke Volume ◽  
Negative Pressure ◽  
Lower Body Negative Pressure ◽  
Right Atrial ◽  
Lower Body ◽  
Arterial Baroreflex ◽  
Arterial Baroreceptors ◽  
Low Levels ◽  
Cardiopulmonary Baroreceptors

Low levels (i.e., ≤20 mmHg) of lower body negative pressure (LBNP) have been utilized to unload “selectively” cardiopulmonary baroreceptors in humans, since steady-state mean arterial pressure and heart rate (HR) have been found unchanged at such levels. However, transient reductions in blood pressure (BP), followed by reflex compensation, may occur without detection, which could unload arterial baroreceptors. The purposes of this study were to test the hypothesis that the arterial baroreflex is engaged even during low levels of LBNP and to determine the time course of changes in hemodynamics. Fourteen healthy individuals (age range 20–54 yr) were studied. BP (Portapres and Suntech), HR (ECG), pulmonary capillary wedge pressure (PCWP) or pulmonary artery diastolic pressure (PDP) and right atrial pressure (RAP) (Swan-Ganz catheter) and hemodynamics (Modelflow) were recorded continuously at baseline and −15- and −30-mmHg LBNP for 6 min each. Application of −15-mmHg LBNP resulted in rapid and sustained falls in RAP and PCWP or PDP, progressive decreases in cardiac output and stroke volume, followed subsequently by transient reductions in both systolic and diastolic BP, which were then restored through the arterial baroreflex feedback mechanism after ∼15 heartbeats. Additional studies were performed in five subjects using even lower levels of LBNP, and this transient reduction in BP was observed in three at −5- and in all at −10-mmHg LBNP. The delay for left ventricular stroke volume to fall at −15-mmHg LBNP was about 10 cardiac cycles. An increase in systemic vascular resistance was detectable after 20 heartbeats during −15-mmHg LBNP. Steady-state BP and HR remained unchanged during mild LBNP. However, BP decreased, while HR increased, at −30-mmHg LBNP. These results suggest that arterial baroreceptors are consistently unloaded during low levels (i.e., −10 and −15 mmHg) of LBNP in humans. Thus “selective” unloading of cardiopulmonary baroreceptors cannot be presumed to occur during these levels of mild LBNP.

Breathing through an inspiratory threshold device improves stroke volume during central hypovolemia in humans

2008 ◽  
Vol 104 (5) ◽  
pp. 1402-1409 ◽  
Author(s):  
Kathy L. Ryan ◽  
William H. Cooke ◽  
Caroline A. Rickards ◽  
Keith G. Lurie ◽  
Victor A. Convertino
Keyword(s):  
Cardiac Output ◽  
Arterial Pressure ◽  
Stroke Volume ◽  
Lower Body Negative Pressure ◽  
Systolic Arterial Pressure ◽  
Intrathoracic Pressure ◽  
Subsequent Increase ◽  
Arterial Blood ◽  
Threshold Device ◽  
Inspiratory Resistance

Inspiratory resistance induced by breathing through an impedance threshold device (ITD) reduces intrathoracic pressure and increases stroke volume (SV) in supine normovolemic humans. We hypothesized that breathing through an ITD would also be associated with a protection of SV and a subsequent increase in the tolerance to progressive central hypovolemia. Eight volunteers (5 men, 3 women) were instrumented to record ECG and beat-by-beat arterial pressure and SV (Finometer). Tolerance to progressive lower body negative pressure (LBNP) was assessed while subjects breathed against either 0 (sham ITD) or −7 cmH2O inspiratory resistance (active ITD); experiments were performed on separate days. Because the active ITD increased LBNP tolerance time from 2,014 ± 106 to 2,259 ± 138 s ( P = 0.006), data were analyzed (time and frequency domains) under both conditions at the time at which cardiovascular collapse occurred during the sham experiment to determine the mechanisms underlying this protective effect. At this time point, arterial blood pressure, SV, and cardiac output were higher ( P ≤ 0.005) when breathing on the active ITD rather than the sham ITD, whereas indirect indicators of autonomic activity (low- and high-frequency oscillations of the R-to-R interval) were not altered. ITD breathing did not alter the transfer function between systolic arterial pressure and R-to-R interval, indicating that integrated baroreflex sensitivity was similar between the two conditions. These data show that breathing against inspiratory resistance increases tolerance to progressive central hypovolemia by better maintaining SV, cardiac output, and arterial blood pressures via primarily mechanical rather than neural mechanisms.

Studies on the adaptability of three breeds of sheep to a tropical environment modified by altitude IV. Role of the fleece in thermoregulation in German Merino ewes

1960 ◽  
Vol 55 (3) ◽  
pp. 311-315
Author(s):  
R. B. Symington
Keyword(s):  
Thermal Stress ◽  
Body Temperature ◽  
Respiratory Rate ◽  
Skin Temperature ◽  
Rectal Temperature ◽  
High Heat ◽  
Diurnal Fluctuation ◽  
Body Temperature Regulation ◽  
Southern Rhodesia

The influence of fleece on thermoregulation in German Merino ewes was investigated in Rhodesia. Comparative heat tolerances of Persian Blackhead, indigenous Native and shorn and unshorn Merino ewes were obtained during the hottest month of the year in Northern Rhodesia. The main thermolytic responses in unshorn, partially shorn and completely shorn Merino ewes were measured at 7.0 a.m.; 10.0 a.m.; 1.0 p.m. and 4.0 p.m. during April in Southern Rhodesia.1. Unshorn Merino ewes showed more and shorn Merino ewes less effective body temperature regulation than Persian or Native ewes. High heat tolerance in unshorn Merinos was due primarily to insulation by the fleece and not to more efficient physiological thermolysis than in hair breeds. No ewe showed signs of undue thermal stress and feed intake was not affected by heat.2. Increases in rectal temperature and respiratory rate between 7.0 a.m. and 1.0 p.m. of Merinos in Southern Rhodesia were related inversely to fleece length. Body temperature did not differ significantly at 1.0 p.m. owing to differential rates of increase in respiratory rate.3. Magnitude of the diurnal fluctuation in skin temperature was also related inversely to fleece length. Partially shorn ewes, however, began with and maintained highest skin temperature through the heat of the day. In all groups skin temperature fell after 10.0 a.m. although ambient temperature continued to rise. This fall could not be attributed to sweating since moisture secretion declined simultaneously.

scholarly journals Small reductions in skin temperature after onset of a simulated hemorrhagic challenge improve tolerance in exercise heat-stressed individuals

2018 ◽  
Vol 315 (3) ◽  
pp. R539-R546
Author(s):  
Claire E. Trotter ◽  
Faith K. Pizzey ◽  
Philip M. Batterson ◽  
Robert A. Jacobs ◽  
James Pearson
Keyword(s):  
Heat Stress ◽  
Mean Arterial Pressure ◽  
Skin Temperature ◽  
Healthy Subjects ◽  
Lower Body Negative Pressure ◽  
Stress Index ◽  
Lower Body ◽  
Vascular Conductance ◽  
Cumulative Stress ◽  
Cutaneous Vascular Conductance

We investigated whether small reductions in skin temperature 60 s after the onset of a simulated hemorrhagic challenge would improve tolerance to lower body negative pressure (LBNP) after exercise heat stress. Eleven healthy subjects completed two trials (High and Reduced). Subjects cycled at ~55% maximal oxygen uptake wearing a warm water-perfused suit until core temperatures increased by ~1.2°C before lying supine and undergoing LBNP to presyncope. LBNP tolerance was quantified as cumulative stress index (CSI; product of each LBNP level multiplied by time; mmHg·min). Skin temperature was similarly elevated from baseline before LBNP and remained elevated 60 s after the onset of LBNP in both High (37.72 ± 0.52°C) and Reduced (37.95 ± 0.54°C) trials (both P < 0.0001). At 60%CSI skin temperature remained elevated in the High trial (37.51 ± 0.56°C) but was reduced to 34.97 ± 0.72°C by the water-perfused suit in the Reduced trial ( P < 0.0001 between trials). Cutaneous vascular conductance was not different between trials [High: 1.57 ± 0.43 vs. Reduced: 1.39 ± 0.38 arbitrary units (AU)/mmHg; P = 0.367] before LBNP but decreased to 0.67 ± 0.19 AU/mmHg at 60%CSI in the Reduced trial while remaining unchanged in the High trial ( P = 0.002 between trials). CSI was higher in the Reduced (695 ± 386 mmHg·min) relative to the High (441 ± 290 mmHg·min; P = 0.023) trial. Mean arterial pressure was not different between trials at presyncope (High: 62 ± 10 vs. Reduced: 62 ± 9 mmHg; P = 0.958). Small reductions in skin temperature after the onset of a simulated hemorrhagic challenge improve LBNP tolerance after exercise heat stress. This may have important implications regarding treatment of an exercise heat-stressed individual (e.g., soldier) who has experienced a hemorrhagic injury.

Pre-hospital hypothermia is associated with transfusion risk after traumatic injury

CJEM ◽  
2020 ◽  
Vol 22 (S2) ◽  
pp. S12-S20
Author(s):  
Naheed K. Jivraj ◽  
Lilia Kaustov ◽  
Kennedy Ning Hao ◽  
Rachel Strauss ◽  
Jeannie Callum ◽  
...  
Keyword(s):  
Care Center ◽  
Tertiary Care ◽  
Traumatic Injury ◽  
Multivariable Analysis ◽  
Hospital Setting ◽  
Multivariable Logistic Regression Analysis ◽  
Trauma Patients ◽  
Injured Patients ◽  
Emergent Surgery ◽  
Rbc Transfusion

ABSTRACTObjectivesIn traumatically injured patients, excessive blood loss necessitating the transfusion of red blood cell (RBC) units is common. Indicators of early RBC transfusion in the pre-hospital setting are needed. This study aims to evaluate the association between hypothermia (<36°C) and transfusion risk within the first 24 hours after arrival to hospital for a traumatic injury.MethodsWe completed an audit of all traumatically injured patients who had emergent surgery at a single tertiary care center between 2010 and 2014. Using multivariable logistic regression analysis, we evaluated the association between pre-hospital hypothermia and transfusion of ≥1 unit of RBC within 24 hours of arrival to the trauma bay.ResultsOf the 703 patients included to evaluate the association between hypothermia and RBC transfusion, 203 patients (29%) required a transfusion within 24 hours. After controlling for important confounding variables, including age, sex, coagulopathy (platelets and INR), hemoglobin, and vital signs (blood pressure and heart rate), hypothermia was associated with a 68% increased odds of transfusion in multivariable analysis (OR: 1.68; 95% CI: 1.11-2.56).ConclusionsHypothermia is strongly associated with RBC transfusion in a cohort of trauma patients requiring emergent surgery. This finding highlights the importance of early measures of temperature after traumatic injury and the need for intervention trials to determine if strategies to mitigate the risk of hypothermia will decrease the risk of transfusion and other morbidities.

Differential sympathetic nerve and heart rate spectral effects of nonhypotensive lower body negative pressure

2001 ◽  
Vol 281 (2) ◽  
pp. R468-R475 ◽  
Author(s):  
John S. Floras ◽  
Gary C. Butler ◽  
Shin-Ichi Ando ◽  
Steven C. Brooks ◽  
Michael J. Pollard ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Stroke Volume ◽  
Negative Pressure ◽  
Sympathetic Nerve ◽  
Lower Body Negative Pressure ◽  
Muscle Sympathetic Nerve Activity ◽  
Venous Pressure ◽  
Harmonic Component ◽  
Lower Body

Lower body negative pressure (LBNP; −5 and −15 mmHg) was applied to 14 men (mean age 44 yr) to test the hypothesis that reductions in preload without effect on stroke volume or blood pressure increase selectively muscle sympathetic nerve activity (MSNA), but not the ratio of low- to high-frequency harmonic component of spectral power (PL/PH), a coarse-graining power spectral estimate of sympathetic heart rate (HR) modulation. LBNP at −5 mmHg lowered central venous pressure and had no effect on stroke volume (Doppler) or systolic blood pressure but reduced vagal HR modulation. This latter finding, a manifestation of arterial baroreceptor unloading, refutes the concept that low levels of LBNP interrogate, selectively, cardiopulmonary reflexes. MSNA increased, whereas PL/PH and HR were unchanged. This discordance is consistent with selectivity of efferent sympathetic responses to nonhypotensive LBNP and with unloading of tonically active sympathoexcitatory atrial reflexes in some subjects. Hypotensive LBNP (−15 mmHg) increased MSNA and PL/PH, but there was no correlation between these changes within subjects. Therefore, HR variability has limited utility as an estimate of the magnitude of orthostatic changes in sympathetic discharge to muscle.

Heat tolerance in dehydrated steers

1966 ◽  
Vol 66 (1) ◽  
pp. 57-60 ◽  
Author(s):  
W. Bianca
Keyword(s):  
Body Weight ◽  
Respiratory Rate ◽  
Skin Temperature ◽  
Heat Tolerance ◽  
Normal Level ◽  
Heat Production ◽  
Feed Intake ◽  
Metabolic Heat Production ◽  
Metabolic Heat ◽  
Initial Rise

Six steers kept in an environment of 15°C. were deprived of water for four consecutive days. This treatment, by depressing appetite, caused a reduction in voluntary hay intake to one-quarter of its normal level and a decrease in body weight by 10%.In spite of this reduction in feed intake, which must have been accompanied by a fall in metabolic heat production, the animals were less able to tolerate heat than when they were normally watered: during 4 hr. exposures to temperatures of 40.0°C. dry bulb and 32.5°C. wet bulb the waterdepleted animals showed higher values of rectal and skin temperature. This was associated with a slower initial rise and lower final values of respiratory rate (130 versus 155 respirations/min.).

scholarly journals Respiratory Variations in Pulse Pressure Reflect Central Hypovolemia during Noninvasive Positive Pressure Ventilation

2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
Ingrid Elise Hoff ◽  
Lars Øivind Høiseth ◽  
Jonny Hisdal ◽  
Jo Røislien ◽  
Svein Aslak Landsverk ◽  
...  
Keyword(s):  
Stroke Volume ◽  
Pulse Pressure ◽  
Mixed Model ◽  
Positive Pressure Ventilation ◽  
Linear Mixed Model ◽  
Lower Body Negative Pressure ◽  
Noninvasive Positive Pressure Ventilation ◽  
Positive Pressure ◽  
Additional Increase ◽  
Waveform Amplitude

Background. Correct volume management is essential in patients with respiratory failure. We investigated the ability of respiratory variations in noninvasive pulse pressure (ΔPP), photoplethysmographic waveform amplitude (ΔPOP), and pleth variability index (PVI) to reflect hypovolemia during noninvasive positive pressure ventilation by inducing hypovolemia with progressive lower body negative pressure (LBNP).Methods. Fourteen volunteers underwent LBNP of 0, −20, −40, −60, and −80 mmHg for 4.5 min at each level or until presyncope. The procedure was repeated with noninvasive positive pressure ventilation. We measured stroke volume (suprasternal Doppler), ΔPP (Finapres), ΔPOP, and PVI and assessed their association with LBNP-level using linear mixed model regression analyses.Results. Stroke volume decreased with each pressure level (−11.2 mL, 95% CI −11.8, −9.6,P<0.001), with an additional effect of noninvasive positive pressure ventilation (−3.0 mL, 95% CI −8.5, −1.3,P=0.009). ΔPP increased for each LBNP-level (1.2%, 95% CI 0.5, 1.8,P<0.001) and almost doubled during noninvasive positive pressure ventilation (additional increase 1.0%, 95% CI 0.1, 1.9,P=0.003). Neither ΔPOP nor PVI was significantly associated with LBNP-level.Conclusions. During noninvasive positive pressure ventilation, preload changes were reflected by ΔPP but not by ΔPOP or PVI. This implies that ΔPP may be used to assess volume status during noninvasive positive pressure ventilation.

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