Effects of cold modality application with static and intermittent pneumatic compression on tissue temperature and systemic cardiovascular responses

Skin temperature of the knee was effectively reduced when using a new continuous cold-flow cryocompression device: a randomised controlled crossover trial

OBJECTIVE

To determine which temperature settings on a new continuous cold-flow cryocompression device effectively reduce knee skin temperature to 10-15 °C, where pain and swelling are expected to be attenuated.

DESIGN

Randomised controlled crossover trial.

SETTING

University laboratory.

PARTICIPANTS

32 healthy adult participants recruited (1 dropout) with no contraindications to cryocompressive therapy.

INTERVENTION

A k-type thermocouple was used to record skin temperature at baseline and every five minutes during a 30-minute cryocompression treatment in a control condition and when using four different device temperature settings (6 °C, 8 °C, 10 °C, and 12 °C) on a continuous cold-flow cryocompression device. Conditions were labelled Control, Con-6, Con-8, Con-10, and Con-12, respectively.

MAIN OUTCOME MEASURES

Skin temperature change (°C) throughout cryocompression; time taken (mins) to achieve skin temperature < 15 °C; and the difference between final skin temperature and device temperature setting (°C).

RESULTS

Median (IQR) skin temperature after cryocompression was 32.1 °C (29.3-33.4), 12.8 °C (12.1-14.6), 14.3 °C (13.8-15.7), 16.1 °C (15.2-17.3), and 17.7 °C (16.9-18.9) for the Control condition and Con-6, Con-8, Con-10 and Con-12, respectively. It took 20 min (Con-6) and 25 min (Con-8) for skin temperature to reach < 15 °C. A median (IQR) difference of 6.8 °C (6.1-8.6), 6.3 °C (5.8-7.7), 6.1 °C (5.2-7.3), and 5.7 °C (4.9-6.9) for Con-6, Con-8, Con-10, and Con-12, respectively was observed between device temperature setting and final skin temperature.

CONCLUSIONS

The device is recommended as it reduced skin temperature to the therapeutic range of 10-15 °C during a 30-minute treatment when using the 6 °C or 8 °C device temperature settings. Future research should determine optimal treatment lengths for cryocompression. CONTRIBUTION OF THE PAPER.

Immediate Effect of Cryo-Compression Therapy on Biomechanical Properties and Perfusion of Forearm Muscles in Mixed Martial Arts Fighters

Mixed martial arts (MMA) fighters use their arms and hands for striking with the fists, grappling, and defensive techniques, which puts a high load on the forearms and hand muscles. New methods are needed to decrease the risk of injury and increase the effectiveness of regeneration. This study aimed to assess the effectiveness of cryo-compression (CC) therapy of different times (3 and 6 min) on forearm muscles in MMA fighters by investigating muscle pain, stiffness, tension, elasticity strength, and perfusion. Twenty professional male MMA fighters aged 26.5 ± 4.5 years, with training experience of 10.3 ± 5.0 years, were enrolled on an experimental within-group study design. The participants underwent CC therapy at a temperature of 3 °C and compression of 75 mmHg for 3 min and, in the second session, for 6 min. The investigated parameters were in the following order: (1) perfusion in non-reference units (PU), (2) muscle tone (T-[Hz]), (3) stiffness (S-[N/m]), (4) elasticity (E-[arb]), (5) pressure pain threshold (PPT-[N/cm]), and (6) maximum isometric force (Fmax [kgf]) at two time points: (1) at rest-2 min before CC therapy (pre) and (2) 2 min after CC therapy (post). There were significant differences between 3 and 6 min of CC therapy for PU and T. Meanwhile, F, E, PPT, and S were significantly different when comparing pre- to post-conditions. These results provide evidence that CC therapy is a stimulus that significantly affects parameters characterizing muscle biomechanical properties, pain threshold, strength, and tissue perfusion.

A randomised crossover trial of five cryocompression devices' ability to reduce skin temperature of the knee

BACKGROUND

The application of cold and pressure to the knee is a common part of post-operative rehabilitation. Skin temperature should be reduced to within 10-15 °C to optimise the therapeutic benefits of cryocompression. The purpose of this study was to investigate the ability of five different cryocompression devices to reduce skin temperature to within this therapeutic range.

MATERIALS AND METHODS

32 healthy adult participants (mean (SD): age 26.3 (7.9) years; BMI 24.8 (2.7) kg/m2; 20 males) were recruited for this randomised crossover study. Skin temperature was measured 20 mm distal to the patella using a k-type thermocouple every five minutes during a 30-minute treatment with one of five different cryocompression devices (Physiolab S1, GameReady, Cryo/Cuff, VPulse, and a Gel Wrap). Changes in skin temperature over time were compared to baseline within and between conditions. A subjective rating of comfort was also recorded for each device.

RESULTS

The Physiolab S1 and GameReady devices caused significantly lower skin temperatures compared to the VPulse, Gel Wrap, and Cryo/Cuff after 30 minutes (p<0.05). 87-96% reported a positive comfort rating for the Physiolab S1, VPulse, Cryo/Cuff and Gel Wrap, whereas 53% of participants reported a positive comfort rating for the GameReady.

CONCLUSIONS

Only the Physiolab S1 and GameReady devices reduced skin temperature of the knee to within the target range of 10-15 °C. The Physiolab S1 was reportedly more comfortable than the GameReady. Clinicians should be aware of the performance differences of different cryocompression devices to understand which is most likely to provide an effective dose of cold therapy to a joint.

The role of a cryocompression device following total knee arthroplasty to assist in recovery: a randomised controlled trial

PURPOSE

The study sought to investigate the effectiveness of a cryocompression Game Ready™ (GR) versus usual care protocol (UC) on early post-operative recovery following total knee arthroplasty.

METHODS

This study prospectively randomised 72 total knee arthroplasties to a 2-week (from day 0) intervention of GR treatment (n = 36, 63.9% females) or UC of ice with static compression (n = 36, 45.7% females). Knee flexion and extension range of motion (ROM), a visual analogue pain scale and limb circumference were documented at day 1, 2 and 14, as well as 6 weeks post-surgery. Medication usage and length of hospital stay were documented. Patient-reported outcome measures (PROMs) included the Knee Injury and Osteoarthritis Outcome Score and a Patient Satisfaction Questionnaire. Statistical analysis using linear mixed modelling and analysis of variance table with Satterthwaite's method were used along with two-tailed t-tests.

RESULTS

There were no significant group-by-time interactions regarding any of the outcomes. The GR group had 19% lost to follow-up at 2 weeks, while the UC group had 8%. The GR group demonstrated significantly better knee extension ROM at day 1 (p = 0.048) and day 14 (p = 0.007) compared with the UC group. There were no group differences (n.s.) observed in pain, flexion ROM, limb circumference, opioid use or PROMs. Overall, higher pain levels resulted in increased opioid intake (p = 0.002), older patients used significantly less opioids (p < 0.001) and males reported significantly less pain than females (p = 0.048). No adverse effects were observed due to either protocol.

CONCLUSION

Despite patients gaining significantly more knee extension during the initial two-week intervention period when using GR compared to UC, this effect was likely due to chance. No further significant differences were observed between the groups during or after cession of the intervention.

LEVEL OF EVIDENCE

Level 2.

Dynamic intermittent compression cryotherapy with intravenous nefopam results in faster pain recovery than static compression cryotherapy with oral nefopam: post-anterior cruciate ligament reconstruction

PURPOSE

To evaluate the effectiveness of dynamic intermittent compression cryotherapy (DICC) (CryoNov®) with an intravenous nefopam-based pain management protocol (DCIVNPP) in reducing post-operative pain following anterior cruciate ligament reconstruction (ACLR) compared to static compression cryotherapy (SCC) (Igloo®) and oral Nefopam.

METHODS

This was a retrospective analysis of prospectively collected data including 676 patients who underwent primary ACLR in 2022. Patients were either in the DCIVNPP group or in the SCC (control group), and were matched for age, sex, and Lysholm and Tegner scores (338 per arm). The primary outcome was pain on the visual analogue scale (VAS), analyzed in relation to the minimal clinically important difference (MCID) and the Patient Acceptable Symptom State (PASS) thresholds for VAS. The secondary outcome was side effects.

RESULTS

Postoperative pain in the DCIVNPP group was less severe on the VAS than in the control group (p < 0.05). The maximum difference in the VAS between groups was 0.57, which is less than the MCID threshold for VAS. The DCIVNPP group crossed the PASS threshold for VAS on Day 3, sooner than the control group. The side effect profiles were similar in both groups except for higher rates of dizziness and malaise in the DCIVNPP group, and higher rates of abdominal pain in the control group. Most of the side effects decreased over time in both groups, with no significant side effects after Day 3.

CONCLUSION

DCIVNPP effectively allows for faster pain recovery than in the control group. The difference in side effects between the protocols may be due to mode of administration of nefopam.

LEVEL OF EVIDENCE

III.

Efficacy of a commercial dry sleeve cryotherapy system for cooling the equine metacarpus

OBJECTIVE

To determine the ability of a commercial cryotherapy system (Game Ready Equine) to cool the metacarpal subcutaneous tissue and the superficial digital flexor tendon (SDFT) in horses.

STUDY DESIGN

Experimental study.

ANIMALS OR SAMPLE POPULATION

Six healthy adult horses.

METHODS

Thermocouples were implanted into the metacarpal subcutaneous tissues and the SDFT of six horses. Two treatments (cryotherapy or cryotherapy with 5-50 mmHg intermittent compression) were randomly assigned to forelimbs and performed for 20 minutes. Temperatures were compared to the target range of 10-19°C and between groups.

RESULTS

Only one limb in the cryotherapy/compression group reached the target range after cryotherapy. Temperatures did not differ between treatment groups at time 0. Lowest temperatures achieved in the subcutaneous tissue (p = .0043) and SDFT (p = .005) were 4.9 and 7.6°C lower when intermittent compression was applied. Similarly, applying compression induced a maximum change in temperature of approximately 7.0°C in the subcutaneous tissue (p = .014) and 10.2°C in the SDFT (p = .0001).

CONCLUSION

The cryotherapy system did not cool equine subcutaneous tissue or SDFT to the target temperature range, except in one limb. Combining cryotherapy with intermittent compression did result in lower temperatures and a greater change in temperature of the subcutaneous tissue and SDFT.

CLINICAL SIGNIFICANCE

When using this cryotherapy system, the addition of intermittent compression should be considered to achieve lower temperatures and potentially greater reduction in inflammation. Further studies are warranted to determine the effect of longer treatment times, higher compression settings, and the optimal temperature for benefits in normal and diseased equine tissues.

Comparison of a Cryopneumatic Compression Device and Ice Packs for Cryotherapy Following Anterior Cruciate Ligament Reconstruction

Background

The purpose of the current study was to evaluate and compare the effectiveness of a cryopneumatic compression device with that of standard ice packs following arthroscopic anterior cruciate ligament (ACL) reconstruction, with a primary focus on early postoperative pain.

Methods

Participants were divided into two groups: cryopneumatic compression device group (CC group) and standard ice pack group (IP group). Patients in the CC Group (28 patients) received a cryopneumatic compression device (CTC-7, Daesung Maref) treatment, while patients in the IP group (28 patients) received standard ice pack cryotherapy postoperatively. All cryotherapy was applied three times (every 8 hours) per day for 20 minutes until discharge (postoperative day 7). Pain scores were assessed preoperatively and at 4, 7, and 14 days after surgery, and the primary outcome for analysis was pain at postoperative day 4 assessed using a visual analog scale (VAS). Other variables were opioid and rescue medication use, knee and thigh circumferences, postoperative drainage, and joint effusion quantified by a three-dimensional magnetic resonance imaging (MRI) reconstruction model.

Results

The mean pain VAS score and difference in VAS relative to the preoperative measurements for postoperative day 4 were significantly lower in the CC group than in the IP group (p = 0.001 and p = 0.007, respectively). The sum of postoperative drainage and effusion quantified by MRI showed a significant reduction of postoperative effusion in the CC group compared to the IP group (p = 0.015). The average total rescue medication consumption was comparable between the two groups. Circumferential measurements at days 7 and 14 postoperatively relative to those at day 4 (index day) demonstrated no significant differences between the groups.

Conclusions

Compared to standard ice packs, application of cryopneumatic compression was associated with a significant reduction in VAS pain scores and joint effusion during the early postoperative period following ACL reconstruction.

Cryotherapy and compression in sports injury management: a scoping review

Background/Aims

For the management of sports injury, cryotherapy is commonly applied, yet modalities differ extensively in application including levels of compression. The aim of this study was to provide a comprehensive review of the current position in the literature on contemporary cryo-compression applications for musculoskeletal sports injury management.

Methods

A total of eight databases were searched: Sport Discus, Science Direct, CINHAL, Scopus, PubMed, Cochrane, ProQuest and MEDLINE. Publications were restricted to 30 years and had to be in the English language. Medical subject headings, free-text words, and limiting descriptors for concepts related to cryotherapy and compression for sports injury were applied. Inclusion criteria determined at least one modality of cryotherapy treatment applied simultaneous to compression or as a comparison, relevant to sports injury management. Modalities included cryo-compressive devices and gel/ice packs, in association with concomitant compression. Male, female, healthy and injured participants were included. Two reviewers independently selected eligible articles, resulting in 22 studies meeting the inclusion criteria following full-text appraisal.

Results

Inconsistent methodologies, low sample sizes and variability in outcome measures provided uncertainty over optimum protocols. A lack of previous understanding in the protocols in the available literature for isolated cryotherapy/compression applications prevents understanding of the therapeutic benefits of combined cryo-compression. No definitive agreement behind optimal cryo-compression applications were identified collectively from studies other than the consensus that compression aids the magnitude of cooling.

Conclusions

Although compression appears a useful adjunct to cooling modalities for the management of sports injury, no definitive agreement on optimum compression concurrent with cooling protocols were drawn from the studies. This was because of several methodological gaps in reporting throughout studies, highlighting a lack of studies that represent applications of compression and cryotherapy within a sporting context or applied nature within the available research.

Recovery profiles of eccentric hamstring strength in response to cooling and compression

INTRODUCTION

The effectiveness of different forms of cryotherapy and combined compression (cryo-compression) commonly used in sport to enhance recovery following exercise are not fully understood. Therefore, the exploration of protocols that use contemporary cryo-compression is warranted. The purpose of the study was to investigate the effectiveness of using a cryo-compression device to recover hamstrings eccentric strength following a fatiguing exercise.

METHODS

Eighteen healthy male adult footballers were randomly allocated to receive cryo-compression or rest following a lower limb fatiguing protocol. Cryo-compression was applied for 15-min, target temperature of 10 °C, and high intermittent pressure (5-75 mm Hg) using the Game Ready® device. Rest consisted of 15-min in a prone position on a plinth. To induce hamstring fatigue, participants performed the Yo-Yo intermittent fatigue test (IFT). Skin surface temperature (T_sk) and hamstring eccentric strength measures were taken at three time points; pre-IFT, immediately post-fatigue test (IPFT), and immediately post-intervention (IPI) (rest or Game Ready®). Participants returned one week later and performed the Yo-Yo IFT again and were exposed to the opposite intervention and data collection.

RESULTS

Significant decreases in T_sk over the posterior thigh were reported for all timepoints compared to pre cryo-compression temperatures (p=<0.05). Overall data displayed no significant main effects for timepoint or condition for PT or AvT (p=<0.05). There was no timepoint × condition interaction for PT or AvT (p=<0.05). Collapse of the data by condition (CC/R) demonstrated no significant effect for time for PT or AvT (p=>0.05).

CONCLUSIONS

No significant changes in HES occurred after exposure to cryo-compression or rest applied immediately following the Yo-Yo IFT. Further investigations to maximise beneficial application of contemporary cryo-compression applications in sport are required. Multiple measures of performance over rewarming periods, within competitive training schedules after sport-specific training are required to develop optimal cooling protocols for recovery.

Continuous-flow cryocompression therapy penetrates to bone level in hip fracture patients in a numerical simulation

BACKGROUND

The aim of this study was to define deep tissue temperature during cryotherapy in postoperative hip fracture patients, by using measured skin temperature as input parameter for a simple numerical model. Second, an association was investigated between pain and tissue temperature distribution, to assess cryotherapy-induced analgesia of soft tissue-derived pain.

METHODS

Data from 35 participants in an ongoing trial was used. In three subjects who consented on optional measurements, skin temperature was measured in 3 days during and after cryotherapy. A simple numerical model was developed to calculate tissue temperature distribution during cryotherapy.

RESULTS

Inter and intrasubject skin temperature displayed high variation: trochanter 11-27 °C, mid-femur 11-24 °C, distal femur 10-16 °C. Predicted temperatures decreased to 20 °C at 1 cm, 26 °C at 2 cm, and 30 °C at 3 cm tissue depth. Smallest soft tissue layer was measured at the trochanter; 42% had less than 30 mm and 21% had less than 20 mm. Numeric rating scale pain varied (mean = 2.14; SD = 1.92), and no association was found between pain and decrease in temperature (r = 0.064; p = 0.204).

CONCLUSIONS

Cryotherapy was predicted to reduce temperature up to 3 cm; in cachectic patients, this reaches the bone, where it might have implications for bone tissue healing when treated for a prolonged period of time. Cryotherapy-induced analgesia is likely to originate from skin analgesia rather than analgesia of muscle or bone-derived pain.

Effectiveness of Salted Ice Bag Versus Cryocompression on Decreasing Intramuscular and Skin Temperature

CONTEXT

Rest, ice, compression, and elevation are commonly recommended immediately after injury. Traditionally, ice bag (IB) with elastic wrap compression has been utilized; however, recently intermittent cryocompression units are being used. Limited research has evaluated tissue temperature decreases with intermittent cryocompression units.

OBJECTIVE

Evaluate magnitude of muscle and skin cooling.

DESIGN

Repeated-measures counterbalanced study.

SETTING

University research laboratory.

PATIENTS OR OTHER PARTICIPANTS

Twelve healthy college-aged participants (4 males and 8 females; age = 23.08 [1.93] y; height = 171.66 [9.47] cm; mass = 73.67 [13.46] kg; subcutaneous thickness = 0.90 [0.35] cm) without compromised circulation or injury.

INTERVENTION(S)

Salted IB, GameReady (GR), and PowerPlay-ice bag (PP-ice) were applied to the posterior aspect of the nondominant calf for 30 minutes; participants underwent each treatment in counterbalanced order.

MAIN OUTCOME MEASURE(S)

Muscle temperature measured via 21-gauge catheter thermocouple; skin temperature measured via a surface thermocouple. Temperatures were recorded at baseline and during a 30-minute treatment. Correlations were evaluated between muscle and skin temperatures.

RESULTS

Nonsignificant treatment × time interaction and nonsignificant main effect of treatment for intramuscular cooling. Mean Decrease From Baseline: IB, 6.4°C (±2.8); GR, 5.4°C (±1.1); PP-ice, 4.8°C (±2.8). Nonsignificant treatment × time interaction for skin cooling (F_20,200 = 1.440, P = .65, ηp2=.346 , and observed β = 0.773), but significant main effect for treatment (F_10,100 = 5.279, P = .03, ηp2=.883 , and observed β = 1.00). Mean Decrease From Baseline: IB, 17.0°C; GR, 16.4°C; PP-ice, 14.6°C. No significant correlation between intramuscular and skin temperatures in any condition at any time point. No significant correlation between adipose tissue thickness and maximum temperature decrease with any modality.

CONCLUSIONS

Salted IB with elastic wrap compression, GR, and PP-ice produced equivalent intramuscular temperature decreases during the treatment period.

Examination of Intramuscular and Skin Temperature Decreases Produced by the PowerPlay Intermittent Compression Cryotherapy

CONTEXT

Previous research has found ice bags are more effective at lowering intramuscular temperature than gel packs. Recent studies have evaluated intramuscular temperature cooling decreases with ice bag versus Game Ready and with the PowerPlay system wetted ice bag inserts; however, intramuscular temperature decreases elicited by PowerPlay with the standard frozen gel pack inserts have not been examined.

OBJECTIVE

Evaluate the rate and magnitude of cooling using PowerPlay with frozen gel pack (PP-gel) option, PowerPlay with wetted ice bag (PP-ice) option, and control (no treatment) on skin and intramuscular temperature (2 cm subadipose).

DESIGN

Repeated-measures counterbalanced study.

SETTING

University research laboratory.

PATIENTS OR OTHER PARTICIPANTS

Twelve healthy college-aged participants (4 men and 8 women; age = 23.08 (1.93) y, height = 171.66 (9.47) cm, mass = 73.67 (13.46) kg, and subcutaneous thickness = 0.90 (0.35) cm).

INTERVENTION(S)

PowerPlay (70 mm Hg) with either wetted ice bag or frozen gel pack was applied to posterior aspect of nondominant calf for 30 minutes; control lay prone for 30 minutes. Participants underwent each treatment in counterbalanced order (minimum 4 d, maximum 10 d between).

MAIN OUTCOME MEASURE(S)

Muscle temperature was measured via 21-gauge catheter thermocouple (IT-21; Physitemp Instruments, Inc). Skin temperature was measured via surface thermocouple (SST-1; Physitemp Instruments, Inc).

RESULTS

Significant treatment-by-time interaction for muscle cooling (F_10,80 = 11.262, P = .01, [Formula: see text], observed β = 0.905) was observed. PP-ice cooled faster than both PP-gel and control from minutes 12 to 30 (all Ps < .05); PP-gel cooled faster than control from minutes 18 to 30 (all Ps < .05). Mean decreases from baseline: PP-ice = 4.8°C (2.8°C), PP-gel = 2.3°C (0.8°C), and control = 1.1°C (0.4°C). Significant treatment-by-time interaction for skin cooling (F_10,80 = 23.920, P = .001, [Formula: see text], observed β = 0.998) was observed. PP-ice cooled faster than both PP-gel and control from minutes 6 to 30 (all Ps < .05); PP-gel cooled faster than control from minutes 12 to 30 (all Ps < .05). Mean decreases from baseline: PP-ice = 14.6°C (4.8°C), PP-gel = 4.0°C (0.9°C), and control = 1.0°C (1.0°C).

CONCLUSIONS

PP-ice produces clinically and statistically greater muscle and skin cooling compared with PP-gel and control.

Postoperative continuous-flow cryocompression therapy in the acute recovery phase of hip fracture surgery-A randomized controlled clinical trial

BACKGROUND

The acute recovery phase after hip fracture surgery is often complicated by severe pain, postoperative blood loss with subsequent transfusion, and delirium. Prevalent comorbidity in hip fracture patients limit the use of opioid-based analgesic therapies, yielding a high risk for inferior pain treatment. Postoperative cryotherapy is suggested to provide an analgesic effect, and to reduce postoperative blood loss. In this prospective, open-label, parallel, multicentre, randomized controlled, clinical trial, we aimed to determine the efficacy of continuous-flow cryocompression therapy (CFCT) in the acute recovery phase after hip fracture surgery.

METHODS

Patients with an intra or extracapsular hip fracture scheduled for surgery were included. Subjects were allocated to receive postoperative CFCT or usual care. The primary endpoint was numeric rating scale (NRS) pain the first 72 postoperative hours. Secondly, analgesic use; postoperative haemoglobin change and transfusion incidence; functional outcome; length of stay; delirium incidence; location of rehabilitation; patient-reported health outcome; complications and feasibility were assessed.

RESULTS

Sixty-one subjects in the control group, and 64 subjects in the CFCT group were analysed. Within the CFCT group, post treatment NRS pain declined 0.31 (p=0.07) at 24h, 0.28 (p=0.07) at 48h, and 0.47 (p=0.002) at 72h relative to pre treatment NRS pain. Sensitivity analysis at 72h showed that NRS pain was 0.92 lower in the CFCT group when compared to the control group (1.50 vs. 2.42; p=0.03). Postoperative analgesic use was comparable between groups. Between postoperative day one and three haemoglobin declined 0.29mmol/l in the CFCT group and 0.51mmol/l in controls (p=0.06), and transfusion incidence was comparable. The timed up and go test and length of stay were also comparable between both groups. Complications, amongst delirium and cryotherapy-related adverse events were not statistically significantly different. Discharge locations did not differ between groups. At outpatient follow-up subjects did not differ in patient-reported health outcome scores. Subjects rated CFCT satisfaction with an average of 7.1 out of 10 points.

CONCLUSIONS

No evidence was recorded to suggest that CFCT has an added value in the acute recovery phase after hip fracture surgery. If patients complete the CFCT treatment schedule, a mild analgesic effect is observed at 72h.

Hypothermia reduces VEGF-165 expression, but not osteogenic differentiation of human adipose stem cells under hypoxia

Cryotherapy is successfully used in the clinic to reduce pain and inflammation after musculoskeletal damage, and might prevent secondary tissue damage under the prevalent hypoxic conditions. Whether cryotherapy reduces mesenchymal stem cell (MSC) number and differentiation under hypoxic conditions, causing impaired callus formation is unknown. We aimed to determine whether hypothermia modulates proliferation, apoptosis, nitric oxide production, VEGF gene and protein expression, and osteogenic/chondrogenic differentiation of human MSCs under hypoxia. Human adipose MSCs were cultured under hypoxia (37°C, 1% O2), hypothermia and hypoxia (30°C, 1% O2), or control conditions (37°C, 20% O2). Total DNA, protein, nitric oxide production, alkaline phosphatase activity, gene expression, and VEGF protein concentration were measured up to day 8. Hypoxia enhanced KI67 expression at day 4. The combination of hypothermia and hypoxia further enhanced KI67 gene expression compared to hypoxia alone, but was unable to prevent the 1.2-fold reduction in DNA amount caused by hypoxia at day 4. Addition of hypothermia to hypoxic cells did not alter the effect of hypoxia alone on BAX-to-BCL-2 ratio, alkaline phosphatase activity, gene expression of SOX9, COL1, or osteocalcin, or nitric oxide production. Hypothermia decreased the stimulating effect of hypoxia on VEGF-165 gene expression by 6-fold at day 4 and by 2-fold at day 8. Hypothermia also decreased VEGF protein expression under hypoxia by 2.9-fold at day 8. In conclusion, hypothermia decreased VEGF-165 gene and protein expression, but did not affect differentiation, or apoptosis of MSCs cultured under hypoxia. These in vitro results implicate that hypothermia treatment in vivo, applied to alleviate pain and inflammation, is not likely to harm early stages of callus formation.

Cryotherapy-Induced Persistent Vasoconstriction After Cutaneous Cooling: Hysteresis Between Skin Temperature and Blood Perfusion

The goal of this study was to investigate the persistence of cold-induced vasoconstriction following cessation of active skin-surface cooling. This study demonstrates a hysteresis effect that develops between skin temperature and blood perfusion during the cooling and subsequent rewarming period. An Arctic Ice cryotherapy unit (CTU) was applied to the knee region of six healthy subjects for 60 min of active cooling followed by 120 min of passive rewarming. Multiple laser Doppler flowmetry perfusion probes were used to measure skin blood flow (expressed as cutaneous vascular conductance (CVC)). Skin surface cooling produced a significant reduction in CVC (P < 0.001) that persisted throughout the duration of the rewarming period. In addition, there was a hysteresis effect between CVC and skin temperature during the cooling and subsequent rewarming cycle (P < 0.01). Mixed model regression (MMR) showed a significant difference in the slopes of the CVC-skin temperature curves during cooling and rewarming (P < 0.001). Piecewise regression was used to investigate the temperature thresholds for acceleration of CVC during the cooling and rewarming periods. The two thresholds were shown to be significantly different (P = 0.003). The results show that localized cooling causes significant vasoconstriction that continues beyond the active cooling period despite skin temperatures returning toward baseline values. The significant and persistent reduction in skin perfusion may contribute to nonfreezing cold injury (NFCI) associated with cryotherapy.

Effects of ice massage of the head and spine on heart rate variability in healthy volunteers

OBJECTIVE

Ice massage (IM) is one of the treatment procedures used in hydrotherapy. Though its various physiological/therapeutic effects have been reported, effects of IM of the head and spine on heart rate variability (HRV) have not been studied. Thus, this study evaluated the effects of IM of the head and spine on HRV in healthy volunteers.

METHODS

Thirty subjects were randomly divided into 3 sessions: (1) IM, (2) tap water massage (TWM) and (3) prone rest (PR). Heart rate (HR) and HRV were assessed before and after each intervention session.

RESULTS

A significant increase in the mean of the intervals between adjacent QRS complexes or the instantaneous HR (RRI), square root of mean of sum of squares of differences between adjacent normal to normal (NN) intervals (RMSSD), number of interval differences of successive NN intervals greater than 50 milliseconds (NN50), proportion derived by dividing NN50 by total number of NN intervals along with significant reduction in HR after IM session; significant increase in RRI along with significant reduction in HR after TWM, and a significant increase only in RMSSD after PR were observed. However, there was no significant difference between the sessions.

CONCLUSION

Results of this study suggest that 20 min of IM of the head and spine is effective in reducing HR and improving HRV through vagal dominance in healthy volunteers.