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- Cardiac condition during cooling and rewarming periods of therapeutic hypothermia after cardiopulmonary resuscitation. [JOURNAL ARTICLE]
- BMC Anesthesiol 2014.:78.
Hypothermia has been used in cardiac surgery for many years for neuroprotection. Mild hypothermia (MH) [body temperature (BT) kept at 32-35°C] has been shown to reduce both mortality and poor neurological outcome in patients after cardiopulmonary resuscitation (CPR). This study investigated whether patients who were expected to benefit neurologically from therapeutic hypothermia (TH) also had improved cardiac function.The study included 30 patients who developed in-hospital cardiac arrest between September 17, 2012, and September 20, 2013, and had return of spontaneous circulation (ROSC) following successful CPR. Patient BTs were cooled to 33°C using intravascular heat change. Basal BT, systolic artery pressure (SAP), diastolic artery pressure (DAP), mean arterial pressure (MAP), heart rate, central venous pressure, cardiac output (CO), cardiac index (CI), global end-diastolic volume index (GEDI), extravascular lung water index (ELWI), and systemic vascular resistance index (SVRI) were measured at 36°C, 35°C, 34°C and 33°C during cooling. BT was held at 33°C for 24 hours prior to rewarming. Rewarming was conducted 0.25°C/h. During rewarming, measurements were repeated at 33°C, 34°C, 35°C and 36°C. A final measurement was performed once patients spontaneously returned to basal BT. We compared cooling and rewarming cardiac measurements at the same BTs.SAP values during rewarming (34°C, 35°C and 36°C) were lower than during cooling (P < 0.05). DAP values during rewarming (basal temperature, 34°C, 35°C and 36°C) were lower than during cooling. MAP values during rewarming (34°C, 35°C and 36°C) were lower than during cooling (P < 0.05). CO and CI values were higher during rewarming than during cooling. GEDI and ELWI did not differ during cooling and rewarming. SVRI values during rewarming (34°C, 35°C, 36°C and basal temperature) were lower than during cooling (P < 0.05).To our knowledge, this is the first study comparing cardiac function at the same BTs during cooling and rewarming. In patients experiencing ROSC following CPR, TH may improve cardiac function and promote favorable neurological outcomes.
- Torpor and hypothermia: reversed hysteresis of metabolic rate and body temperature. [JOURNAL ARTICLE]
- Am J Physiol Regul Integr Comp Physiol 2014 Sep 24.
Regulated torpor and unregulated hypothermia are both characterized by substantially reduced body temperature (Tb¬) and metabolic rate (MR), but they differ physiologically. Although the remarkable, medically interesting adaptations accompanying torpor (e.g., tolerance for cold and ischemia, absence of reperfusion injury and disuse atrophy) often do not apply to hypothermia in homeothermic species such as humans, the terms "torpor" and "hypothermia" are often used interchangeably in the literature. To determine how these states differ functionally and to provide a reliable diagnostic tool for differentiating between these two physiologically distinct states, we examined the interrelations between Tb and MR in a mammal (Sminthopsis macroura) undergoing a bout of torpor with those of the hypothermic response of a similar-sized juvenile rat (Rattus norvegicus). Our data show that under similar thermal conditions, 1) cooling rates differ substantially (~5-fold) between the two states; 2) minimum MR is ~7-fold higher during hypothermia than during torpor despite a similar Tb; 3) rapid, endogenously fuelled rewarming occurs in torpor but not hypothermia; and 4) the hysteresis between Tb/MR during warming and cooling proceeds in opposite directions in torpor and hypothermia. We thus demonstrate clear diagnostic physiological differences between these two states that can be used experimentally to confirm whether torpor or hypothermia has occurred. Furthermore, the data can clarify the results of studies investigating the ability of physiological or pharmacological agents to induce torpor. Consequently, we recommend using the terms "torpor" and "hypothermia" in ways that are consistent with the underlying regulatory differences between these two physiological states.
- Therapeutic Hypothermia (Different Depths, Durations, and Rewarming Speeds) for Acute Ischemic Stroke: A Meta-analysis. [JOURNAL ARTICLE]
- J Stroke Cerebrovasc Dis 2014 Sep 16.
Whether therapeutic hypothermia benefits patients with acute ischemic stroke (AIS) remains controversial. The aim of this study was to evaluate the efficacy and safety of the different depths, durations, and rewarming speeds of therapeutic hypothermia for AIS.The MEDLINE (OVID), EMBASE, and Cochrane Central Register of Controlled Trials were systematically searched for randomized controlled trials (RCTs) of therapeutic hypothermia for AIS from the inception of the databases to October 2013. After data extraction and quality assessment, a meta-analysis was performed using RevMan 5.1.A total of 6 RCTs involving 252 AIS patients were eligible for the meta-analysis. Subanalyses stratified by depth, duration, and rewarming speed of therapeutic hypothermia were also performed. Our results showed that therapeutic hypothermia was associated with an increased risk of pneumonia (risk ratio = 3.30, 95% CI 1.48-7.34; P = .003, P for heterogeneity = .91, I(2) = 0%). No significant difference was observed between the 2 groups in terms of neurologic outcomes, mortality, and other complications including symptomatic or fatal intracranial hemorrhage, deep vein thrombosis, and atrial fibrillation.These limited data suggest that therapeutic hypothermia does not significantly improve stroke outcomes and may lead to higher rates of pneumonia. Multicenter RCTs with larger samples are needed to confirm the current findings.
- [Case report - Hemodynamic variables of a deep hypothermic patient over the period of external rewarming]. [English Abstract, Journal Article]
- Anasthesiol Intensivmed Notfallmed Schmerzther 2014 Sep; 49(9):514-9.
Deep accidental hypothermia is a very rare emergency, most of these patients die despite of immediate and adaequate therapy. We report on a hypothermic patient who was in a stable hemodynamic condition and breathing spontaneously at a temperature of 25.5°C. He was rewarmed with non-invasive methods. We describe and discuss the hemodynamic variables of an advanced monitoring during the time of external rewarming.
- Milrinone ameliorates cardiac mechanical dysfunction after hypothermia in an intact rat model. [JOURNAL ARTICLE]
- Cryobiology 2014 Sep 12.
Rewarming from hypothermia is often complicated by cardiac dysfunction, characterized by substantial reduction in stroke volume. Previously we have reported that inotropic agents, working via cardiac β-receptor agonism may exert serious side effects when applied to treat cardiac contractile dysfunction during rewarming. In this study we tested whether Milrinone, a phosphodiesterase III inhibitor, is able to ameliorate such dysfunction when given during rewarming.A rat model designed for circulatory studies during experimental hypothermia with cooling to a core temperature of 15°C, stable hypothermia at this temperature for 3h and subsequent rewarming was used, with a total of 3 groups: 1) A normothermic group receiving Milrinone, 2) a hypothermic group receiving Milrinone the last hour of hypothermia and during rewarming, and 3) a hypothermic saline control group. Hemodynamic function was monitored using a conductance catheter introduced to the left ventricle.After rewarming from 15°C, stroke volume, cardiac output and total peripheral resistance returned to within baseline values in Milrinone treated animals, while these variables were significantly reduced in saline controls.Milrinone ameliorated cardiac dysfunction during rewarming from 15°C. The present results suggest that at low core temperatures and during rewarming from such temperatures, pharmacologic efforts to support cardiovascular function is better achieved by substances preventing cyclic AMP breakdown rather than increasing its formation via β-receptor stimulation.
- Hypothermia in Victims of the Great East Japan Earthquake: A Survey in Miyagi Prefecture. [JOURNAL ARTICLE]
- Disaster Med Public Health Prep 2014 Sep 12.:1-11.
A survey was conducted to describe the characteristics of patients treated for hypothermia after the Great East Japan Earthquake.Written questionnaires were distributed to 72 emergency medical hospitals in Miyagi Prefecture. Data were requested regarding inpatients with a temperature less than 36ºC admitted within 72 hours after the earthquake. The availability of functional heating systems and the time required to restore heating after the earthquake were also documented.A total of 91 inpatients from 13 hospitals were identified. Tsunami victims comprised 73% of the patients with hypothermia. Within 24 hours of the earthquake, 66 patients were admitted. Most patients with a temperature of 32ºC or higher were treated with passive external rewarming with blankets. Discharge without sequelae was reported for 83.3% of patients admitted within 24 hours of the earthquake and 44.0% of those admitted from 24 to 72 hours after the earthquake. Heating systems were restored within 3 days of the earthquake at 43% of the hospitals.Hypothermia in patients hospitalized within 72 hours of the earthquake was primarily due to cold-water exposure during the tsunami. Many patients were successfully treated in spite of the post-earthquake disruption of regional social infrastructure.(Disaster Med Public Health Preparedness. 2014;0:1-11).
- Is enteral feeding tolerated during therapeutic hypothermia? [JOURNAL ARTICLE]
- Resuscitation 2014 Sep 2.
To determine whether patients undergoing therapeutic hypothermia following cardiac arrest tolerate early enteral nutrition.We undertook a single-centre longitudinal cohort analysis of the tolerance of enteral feeding by 55 patients treated with therapeutic hypothermia following resuscitation from cardiac arrest. The observation period was divided into three phases: (1) 24h at target temperature (32-34°C); (2) 24h rewarming to 36.5°C; and (3) 24h maintained at a core temperature below 37.5°C.During period 1, patients tolerated a median of 72% (interquartile range (IQR) 68.7%; range 31.3 to 100%) of administered feed. During period 2 (rewarming phase), a median of 95% (IQR 66.2%; range 33.77 to 100%) of administered feed was tolerated. During period 3 (normothermia) a median of 100% (IQR 4.75%; range 95.25 to 100%) of administered feed was tolerated. The highest incidence of vomiting or regurgitation of feed (19% of patients) occurred between 24-48h of therapy.Patients undergoing therapeutic hypothermia following cardiac arrest may be able to tolerate a substantial proportion of their daily nutritional requirements. It is possible that routine use of prokinetic drugs during this period may increase the success of feed delivery enterally and this could usefully be explored.
- Remote Ischemic Preconditioning is a Safe Adjuvant Technique to Myocardial Protection But Adds No Clinical Benefit After On-Pump Coronary Artery Bypass Grafting. [Journal Article]
- Heart Surg Forum 2014 Aug 1; 17(4):E220-3.
To evaluate the impact of remote ischemic preconditioning (RIPC) on clinical outcome, biological markers of myocardial injury, and its safety in patients undergoing on-pump coronary artery bypass grafting (CABG).This study was conducted at Ch. Pervaiz Elahi Institute of Cardiology (CPEIC) in Multan. The study took place from March 2012 to June 2013. Patients were randomly placed into two groups. Group A (N = 32) did not undergo RIPC; Group B (N = 35) received RIPC after induction of anesthesia. Similar standard general anesthesia, cardiopulmonary technique, myocardial protection strategies, and surgical techniques were used in both groups except the protocol for RIPC. Following postoperative outcome, i.e. cardiac defibrillation after removal of aortic cross clamp during the period of rewarming, demand for intra-aortic balloon pump (IABP), demand for antiarrhythmic before leaving the operation room, postoperative creatine kinase-myocardial band (CK-MB) level (at 1h, 12h, 24h, and 48h after surgery), postoperative serum creatinine level on first postoperative day, postoperative ejection fraction (EF) on third postoperative day, in-hospital mortality, and one-year mortality were noted, prospectively. Safety of protocol of RIPC was estimated by limb ischemia monitored by pulse oximetry during and after procedure of RIPC and postoperative neurapraxia by nerve examination of right upper limb.Post aortic cross clamp release cardiac defibrillation, demand for IABP, demand for high inotropes, and use of antiarrhythmic in the operation room were statistically insignificant in the non-RIPC and RIPC group with P values of .54, .78, .16, and .16, respectively. Mean postoperative CK-MB level (IU/L) showed the following results: At 1h (Group A 20.94 + 1.66, Group B 20.57 + 1.54, P = .35), at 12h (Group A 27.13 + 1.85, Group B 28.05 + 3.04, P = .135), at 24h (Group A 27.63 + 1.7, Group B 27.85 + 2.2, P = .63), and at 48h (Group A 22.95 + 2.76, Group B 23.27 + 3.6, P = .69). First postoperative day serum creatinine (Group A 1.29 + 0.395, Group B 1.33 + 0.57, P = .77) and postoperative ejection fraction percentage on the third postoperative day (Group A 50.78 + 8.72, Group B 50.57 + 8.38, P = .92) showed no statistical difference between two groups. Postoperative low cardiac output state, in-hospital mortality, and one-year mortality also were statistically insignificant between the groups with P values of .93, .29, and .33, respectively. None of the patients in either group showed evidence of limb ischemia and neurapraxia of the right upper limb.RIPC is a safe technique, but it does not have additional clinical benefit after on-pump CABG surgery in the presence of a standard myocardial protective strategy.
- Apparent Diffusion Coefficient Scalars Correlate with Near-Infrared Spectroscopy Markers of Cerebrovascular Autoregulation in Neonates Cooled for Perinatal Hypoxic-Ischemic Injury. [JOURNAL ARTICLE]
- AJNR Am J Neuroradiol 2014 Aug 28.
Neurologic morbidity remains high in neonates with perinatal hypoxic-ischemic injury despite therapeutic hypothermia. DTI provides qualitative and quantitative information about the microstructure of the brain, and a near-infrared spectroscopy index can assess cerebrovascular autoregulation. We hypothesized that lower ADC values would correlate with worse autoregulatory function.Thirty-one neonates with hypoxic-ischemic injury were enrolled. ADC scalars were measured in 27 neonates (age range, 4-15 days) in the anterior and posterior centrum semiovale, basal ganglia, thalamus, posterior limb of the internal capsule, pons, and middle cerebellar peduncle on MRI obtained after completion of therapeutic hypothermia. The blood pressure range of each neonate with the most robust autoregulation was identified by using a near-infrared spectroscopy index. Autoregulatory function was measured by blood pressure deviation below the range with optimal autoregulation.In neonates who had MRI on day of life ≥10, lower ADC scalars in the posterior centrum semiovale (r = -0.87, P = .003, n = 9) and the posterior limb of the internal capsule (r = -0.68, P = .04, n = 9) correlated with blood pressure deviation below the range with optimal autoregulation during hypothermia. Lower ADC scalars in the basal ganglia correlated with worse autoregulation during rewarming (r = -0.71, P = .05, n = 8).Blood pressure deviation from the optimal autoregulatory range may be an early biomarker of injury in the posterior centrum semiovale, posterior limb of the internal capsule, and basal ganglia. Optimizing blood pressure to support autoregulation may decrease the risk of brain injury in cooled neonates with hypoxic-ischemic injury.
- Frostbite of the Hand. [REVIEW]
- J Hand Surg Am 2014 Sep; 39(9):1863-1868.
Frostbite is damage caused by the freezing of tissue owing to exposure to extreme cold. Clinically, it is often difficult to identify the severity of frostbite injury. There may be a wide discrepancy between the extent of damage to the skin versus that to the deeper structures. The initial clinical impression is usually worse than actual tissue damage. In addition to physical examination, diagnostic imaging, especially triple-phase bone scan, has been proposed to help differentiate between superficial and deep damage. Principles of treatment involve rapid rewarming to thaw the tissues and halt direct cellular damage, methods to minimize progressive dermal ischemia, and active wound care to promote timely healing. Pharmacological adjuncts, such as fibrinolytics, have been proposed to minimize tissue damage. Surgical therapy is postponed until there is clear demarcation between healthy and necrotic tissue.