(P1-72) Advanced Surgical Cooling Garment to Combat Heat Stress in CBW Ppe and Hot Surgical Environments

IntroductionHeat stress is an occupational hazard for all personnel requiring Personal Protective Equipment (PPE). Even “breathable PPE” increases measurable heat stress in active troops and surgical personnel. A novel negative-pressure, semipermeable surgical cooling vests for use in the operating theater was jointly developed by Mountain Laurel Biomedical, Hamilton Sundstrand, and Hartford Hospital.Materials and MethodsSurgical personnel alternated between wearing cooling garment vs no cooling under their surgical gowns (PPE) during surgical procedures lasting up to several hours. Tympanic temperatures were monitored for safety. A questionnaire was completed after the conclusion of surgery to assess perception of comfort. Trials began at ∼18 deg C, but ambient temperature was increased to 24 deg C (40–50% RH) for the third series of trials. Results: The study was terminated prematurely. After wearing the cooling vest, surgeons refused to complete additional control trials due to the heat. They demanded to use the cooling device for all surgery, even outside the protocol! Vest wearers remained dry and reported a statistically significant (p < 0.0001) greater level of comfort compared to control subjects. The weight, fit, and mobility restriction of the vest was not clinically significant.ConclusionActive cooling and drying using a negative pressure cooling vest improves subjective thermal comfort with minimal perceived impact on mobility during surgical procedures. This technology may have utility in other fields that utilize PPE. The Chemical Biological Warfare (CBW) ensemble, in particular, is a promising candidate. Heat stress from PPE ensemble even if “breathable” -Cooling at ∼100 watts with 18 deg C water -Semipermeable membrane allows condensation removal. Wearer stays cool and dry. -Negative pressure prevents coolant loss if punctured -Minimal perceived restriction of shoulder, neck, and waist range of motion - Light weight ∼1.5 lbs. (0.68 kg) - Quick disconnects allow options for cooling source.

Download Full-text

Sweat loss during heat stress contributes to subsequent reductions in lower-body negative pressure tolerance

Experimental Physiology ◽

10.1113/expphysiol.2012.068171 ◽

2012 ◽

Vol 98 (2) ◽

pp. 473-480 ◽

Cited By ~ 21

Author(s):

Rebekah A. I. Lucas ◽

Matthew S. Ganio ◽

James Pearson ◽

Craig G. Crandall

Keyword(s):

Heat Stress ◽

Negative Pressure ◽

Lower Body Negative Pressure ◽

Lower Body ◽

Sweat Loss ◽

Pressure Tolerance

Download Full-text

Development of a Cooling Garment With Encapsulated PCM

10.1115/imece2000-2237 ◽

2000 ◽

Author(s):

David P. Colvin ◽

Virginia S. Colvin ◽

Yvonne G. Bryant ◽

Linda G. Hayes ◽

Michael A. Spieker

Keyword(s):

Heat Stress ◽

Phase Change ◽

Protective Clothing ◽

Environmental Control ◽

Packed Bed ◽

High Heat ◽

Industrial Workers ◽

Latent Heat Storage ◽

Innovation Research ◽

Cooling Garment

Abstract Under SBIR (Small Business Innovation Research) programs from the U.S. Marine Corps, investigators at Triangle Research and Development Corporation (TRDC) have conducted research toward the development of a unique passive cooling garment to provide significant microclimate cooling to Marines dressed in NBC (Nuclear/Biological/Chemical) protective clothing. The patented PECS (Protective Environmental Control System) garment utilizes 3–4 mm diameter macroencapsulated phase change material (macroPCM) particles distributed throughout a lightweight and highly breathable vest garment to provide 1–3 hours of cooling in high heat stress environments. With polymer walls encapsulating the paraffin PCM, the macroPCMs provide a wearable, packed bed heat exchanger that is flexible, highly breathable, and undergoes its solid/liquid phase change from 25–28°C, where its high latent heat storage can reach 60 calories/gram. This cooling range is at elevated and more comfortable temperatures than gel media used in other passive microclimate garments, which store their cold near 0°C and can cause shivering and discomfort. Although other microclimate garments require refrigeration or freezers to thermally recharge the cooling media, the passive 5-lb PECS cooling garment can be thermally recharged in the field at room temperatures (15–20°C) without refrigeration. Although earlier publications described the principles for such a cooling garment, this publication is the first to describe the garment’s construction, development and testing. Extensive laboratory testing has included Marine volunteers on a treadmill in a heated environmental chamber while dressed in Level IV MOPP and Level A protective clothing and a gas mask. PECS has also been used by costumed characters at Walt Disney World to provide extended cooling within an extended heat stress environment. Besides military uses, passive macroPCM garments should find other applications; including: protective clothing for firefighters, industrial workers, costumed characters and persons with heat stress disabilities.

Download Full-text

THE ROLE OF CLOSED WOUND NEGATIVE PRESSURE SUCTION IN RADICAL SURGICAL PROCEDURES OF THE HEAD AND NECK

The Laryngoscope ◽

10.1288/00005537-196401000-00005 ◽

1964 ◽

Vol LXXIV (1) ◽

pp. 70???94

Author(s):

W. COPLEY MCLEAN

Keyword(s):

Head And Neck ◽

Surgical Procedures ◽

Negative Pressure ◽

Pressure Suction

Download Full-text

Should closed reduction of the dislocated hip be attempted after failed Pavlik harness treatment in developmental dysplasia of the hip?

Bone & Joint Open ◽

10.1302/2633-1462.28.bjo-2021-0088.r1 ◽

2021 ◽

Vol 2 (8) ◽

pp. 584-588

Author(s):

Matthew Arneill ◽

Aidan Cosgrove ◽

Elaine Robinson

Keyword(s):

Northern Ireland ◽

Surgical Procedures ◽

Closed Reduction ◽

Developmental Dysplasia ◽

General Anaesthetic ◽

Pavlik Harness ◽

Total Cohort ◽

Clinically Significant ◽

Dysplasia Of The Hip

Aims To determine the likelihood of achieving a successful closed reduction (CR) of a dislocated hip in developmental dysplasia of the hip (DDH) after failed Pavlik harness treatment We report the rate of avascular necrosis (AVN) and the need for further surgical procedures. Methods Data was obtained from the Northern Ireland DDH database. All children who underwent an attempted closed reduction between 2011 and 2016 were identified. Children with a dislocated hip that failed Pavlik harness treatment were included in the study. Successful closed reduction was defined as a hip that reduced in theatre and remained reduced. Most recent imaging was assessed for the presence of AVN using the Kalamchi and MacEwen classification. Results There were 644 dislocated hips in 543 patients initially treated in Pavlik harness. In all, 67 hips failed Pavlik harness treatment and proceeded to arthrogram (CR) under general anaesthetic at an average age of 180 days. The number of hips that were deemed reduced in theatre was 46 of the 67 (69%). A total of 11 hips re-dislocated and underwent open reduction, giving a true successful CR rate of 52%. For the total cohort of 67 hips that went to theatre for arthrogram and attempted CR, five (7%) developed clinically significant AVN at an average follow-up of four years and one month, while none of the 35 hips whose reduction was truly successful developed clinically significant AVN. Conclusion The likelihood of a successful closed reduction of a dislocated hip in the Northern Ireland population, which has failed Pavlik harness treatment, is 52% with a clinically significant AVN rate of 7%. As such, we continue to advocate closed reduction under general anaesthetic for the hip that has failed Pavlik harness. Cite this article: Bone Jt Open 2021;2(8):584–588.

Download Full-text

A Cooling Vest for Construction Workers

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.1061-1062.728 ◽

2014 ◽

Vol 1061-1062 ◽

pp. 728-732

Author(s):

Min Wu ◽

Joe Dong ◽

Andy Zhao ◽

Wai Ching Tang ◽

Willy Sher ◽

...

Keyword(s):

Heat Stress ◽

Body Temperature ◽

Phase Change ◽

Phase Change Material ◽

Construction Workers ◽

Cooling Garment ◽

Change Material

Construction workers are vulnerable to heat stress, and a number of heat-related injuries and deaths have been reported. This study thus introduces a phase change material (PCM) based cooling garment designed for construction workers. The PCM cooling garment will be effective in reducing the workers body temperature and can extend their maximum tolerable time on sites.

Download Full-text

Surgical Site Infections Following Ambulatory Surgery Procedures

50 Studies Every Anesthesiologist Should Know ◽

10.1093/med/9780190237691.003.0030 ◽

2018 ◽

pp. 158-162

Keyword(s):

Quality Improvement ◽

Surgical Procedures ◽

Ambulatory Surgery ◽

Surgical Site Infections ◽

High Volume ◽

Low Risk ◽

Inpatient Setting ◽

Cost Burden ◽

Actual Number ◽

Clinically Significant

This case focuses on surgical site infections by asking the question: What is the incidence of clinically significant surgical site infections (CS-SSIs) following low- to moderate-risk ambulatory surgery in patients at low risk for surgical complications? This retrospective analysis found that the overall rate of CS-SSIs following ambulatory surgery is relatively low, at approximately 3.09 per 1,000 ambulatory surgical procedures. However, because of the high volume of ambulatory cases annually, the actual number of acute care visits due to CS-SSIs is large in aggregate. More than 90% of the CS-SSIs in this analysis required treatment in an inpatient setting, demonstrating a substantial cost burden. Thus, surgical site infections merit quality improvement efforts to minimize their occurrence.

Download Full-text

Pharyngeal critical pressure in children with mild sleep-disordered breathing

Journal of Applied Physiology ◽

10.1152/japplphysiol.01444.2005 ◽

2006 ◽

Vol 101 (3) ◽

pp. 734-739 ◽

Cited By ~ 9

Author(s):

R. F. Fregosi ◽

S. F. Quan ◽

W. L. Morgan ◽

J. L. Goodwin ◽

R. Cabrera ◽

...

Keyword(s):

Negative Pressure ◽

Sleep Disordered Breathing ◽

Critical Pressure ◽

Upper Airway ◽

Obstructive Sleep ◽

Airway Collapsibility ◽

Adults And Children ◽

Measured Flow ◽

Clinically Significant ◽

Disordered Breathing

There is evidence that narrowing or collapse of the pharynx can contribute to obstructive sleep-disordered breathing (SDB) in adults and children. However, studies in children have focused on those with relatively severe SDB who generally were recruited from sleep clinics. It is unclear whether children with mild SDB who primarily have hypopneas, and not frank apnea, also have more collapsible airways. We estimated airway collapsibility in 10 control subjects (9.4 ± 0.5 yr old; 1.9 ± 0.2 hypopneas/h) and 7 children with mild SDB (10.6 ± 0.5 yr old; 11.5 ± 0.1 hypopneas/h) during stable, non-rapid eye movement sleep. None of the subjects had clinically significant enlargement of the tonsils or adenoids, nor had any undergone previous tonsillectomy or adenoidectomy. Airway collapsibility was measured by brief (2-breath duration) and sudden reductions in pharyngeal pressure by connecting the breathing mask to a negative pressure source. Negative pressure applications ranging from −1 to −20 cmH2O were randomly applied in each subject while respiratory airflow and mask pressure were measured. Flow-pressure curves were constructed for each subject, and the x-intercept gave the pressure at zero flow, the so-called critical pressure of the upper airway (Pcrit). Pcrit was significantly higher in children with SDB than in controls (−10.8 ± 2.8 vs. −15.7 ± 1.2 cmH2O; P < 0.05). There were no significant differences in the slopes of the pressure-flow relations or in baseline airflow resistance. These data support the concept that intrinsic pharyngeal collapsibility contributes to mild SDB in children.

Download Full-text

Impact of environmental stressors on tolerance to hemorrhage in humans

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.00235.2018 ◽

2019 ◽

Vol 316 (2) ◽

pp. R88-R100 ◽

Cited By ~ 4

Author(s):

Craig G. Crandall ◽

Caroline A. Rickards ◽

Blair D. Johnson

Keyword(s):

Heat Stress ◽

Blood Loss ◽

Cause Of Death ◽

Negative Pressure ◽

Lower Body Negative Pressure ◽

Environmental Stressors ◽

Lower Body ◽

Physiological Conditions ◽

Exercise Induced ◽

The Impact

Hemorrhage is a leading cause of death in military and civilian settings, and ~85% of potentially survivable battlefield deaths are hemorrhage-related. Soldiers and civilians are exposed to a number of environmental and physiological conditions that have the potential to alter tolerance to a hemorrhagic insult. The objective of this review is to summarize the known impact of commonly encountered environmental and physiological conditions on tolerance to hemorrhagic insult, primarily in humans. The majority of the studies used lower body negative pressure (LBNP) to simulate a hemorrhagic insult, although some studies employed incremental blood withdrawal. This review addresses, first, the use of LBNP as a model of hemorrhage-induced central hypovolemia and, then, the effects of the following conditions on tolerance to LBNP: passive and exercise-induced heat stress with and without hypohydration/dehydration, exposure to hypothermia, and exposure to altitude/hypoxia. An understanding of the effects of these environmental and physiological conditions on responses to a hemorrhagic challenge, including tolerance, can enable development and implementation of targeted strategies and interventions to reduce the impact of such conditions on tolerance to a hemorrhagic insult and, ultimately, improve survival from blood loss injuries.

Download Full-text

Divergent roles of plasma osmolality and the baroreflex on sweating and skin blood flow

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.00411.2011 ◽

2012 ◽

Vol 302 (5) ◽

pp. R634-R642 ◽

Cited By ~ 24

Author(s):

Aaron G. Lynn ◽

Daniel Gagnon ◽

Konrad Binder ◽

Robert C. Boushel ◽

Glen P. Kenny

Keyword(s):

Blood Flow ◽

Heat Stress ◽

Core Temperature ◽

Skin Blood Flow ◽

Negative Pressure ◽

Lower Body Negative Pressure ◽

Plasma Osmolality ◽

Whole Body ◽

Lower Body ◽

Change In Mean

Plasma hyperosmolality and baroreceptor unloading have been shown to independently influence the heat loss responses of sweating and cutaneous vasodilation. However, their combined effects remain unresolved. On four separate occasions, eight males were passively heated with a liquid-conditioned suit to 1.0°C above baseline core temperature during a resting isosmotic state (infusion of 0.9% NaCl saline) with (LBNP) and without (CON) application of lower-body negative pressure (−40 cmH2O) and during a hyperosmotic state (infusion of 3.0% NaCl saline) with (LBNP + HYP) and without (HYP) application of lower-body negative pressure. Forearm sweat rate (ventilated capsule) and skin blood flow (laser-Doppler), as well as core (esophageal) and mean skin temperatures, were measured continuously. Plasma osmolality increased by ∼10 mosmol/kgH2O during HYP and HYP + LBNP conditions, whereas it remained unchanged during CON and LBNP ( P ≤ 0.05). The change in mean body temperature (0.8 × core temperature + 0.2 × mean skin temperature) at the onset threshold for increases in cutaneous vascular conductance (CVC) was significantly greater during LBNP (0.56 ± 0.24°C) and HYP (0.69 ± 0.36°C) conditions compared with CON (0.28 ± 0.23°C, P ≤ 0.05). Additionally, the onset threshold for CVC during LBNP + HYP (0.88 ± 0.33°C) was significantly greater than CON and LBNP conditions ( P ≤ 0.05). In contrast, onset thresholds for sweating were not different during LBNP (0.50 ± 0.18°C) compared with CON (0.46 ± 0.26°C, P = 0.950) but were elevated ( P ≤ 0.05) similarly during HYP (0.91 ± 0.37°C) and LBNP + HYP (0.94 ± 0.40°C). Our findings show an additive effect of hyperosmolality and baroreceptor unloading on the onset threshold for increases in CVC during whole body heat stress. In contrast, the onset threshold for sweating during heat stress was only elevated by hyperosmolality with no effect of the baroreflex.

Download Full-text