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- The effect of adjusting tracheal tube cuff pressure during deep hypothermic circulatory arrest: A randomised trial. [Journal Article]
- Eur J Anaesthesiol 2014 Sep; 31(9):452-6.
Regular endotracheal tube cuff monitoring may prevent silent aspiration.We hypothesised that active management of the cuff of the tracheal tube during deep hypothermic cardiac arrest would reduce silent subglottic aspiration. We also determined to study its effect on postoperative mechanical ventilation and the incidence of postoperative positive tracheal cultures.A randomised clinical trial.The study was conducted in a University Teaching Hospital from September 2008 to November 2009.Twenty-four patients undergoing elective pulmonary endarterectomy were included in the study.After induction of general anaesthesia and tracheal intubation, the cuff of the tracheal tube was inflated to 25 cmH2O. Following this, 1 ml of methylene blue dye diluted in 2 ml of physiological saline was injected into the hypopharynx. Patients were randomly assigned to active cuff management during cooling and warming (where cuff pressure was monitored and the cuff was reinflated if it dropped below 20 cmH2O, or deflated if pressure exceeded 30 cmH2O) or passive monitoring (where cuff pressure was monitored but volume was not altered). Before weaning from cardiopulmonary bypass, fibreoptic bronchoscopy was performed. Silent aspiration was then diagnosed if blue dye was seen in the trachea below the cuff of the tube.The primary aim of this study was to determine the incidence of silent aspiration. Secondary outcomes included duration of postoperative mechanical ventilation of the lungs and incidence of positive culture of tracheal aspirate.Active cuff management patients were younger than controls (51.2 ± 11.6 vs. 63.2 ± 9 years, P = 0.028), but otherwise the two groups were similar. The primary endpoint was reached because we showed that silent aspiration was significantly less frequent in the study group (0/12 vs. 8/12 patients, P = 0.001). Significantly lower intracuff pressures were measured in the control group patients at several timepoints during cooling, just before hypothermic arrest and at all timepoints during rewarming.We recommend that the cuff of the tracheal tube should be checked regularly during surgery under deep hypothermia, and the cuff pressure adjusted as required.
- [Immunogenicity of allogeneic freezing periosteum and bone marrow]. [English Abstract, Journal Article]
- Zhongguo Xiu Fu Chong Jian Wai Ke Za Zhi 2014 May; 28(5):649-53.
To investigate the immunogenicity of freezing periosteum and bone marrow during allogeneic joint transplantation, and to explore proper pretreatment of allogeneic joint.The allogeneic periosteum and bone marrow were harvested from knee joints of 5 New Zealand white rabbits (aged, 6 months; weighing, 2.6-3.0 kg). After gradient cooling, the tissue was cryopreserved for 1 month. The freezing periosteum and bone marrow were grinded to pieces after rewarming to prepare the suspension of periosteum and bone marrow. Eighteen Chinchilla rabbits (aged, 6 months; weighing, 2.1-2.8 kg) were divided into 3 groups randomly: normal saline injection group (group A, n = 6), periosteum injection group (group B, n = 6), and bone marrow injection group (group C, n=6). The normal saline, periosteum suspension, and bone marrow suspension were injected into the peritoneal cavity in groups A, B, and C, respectively. The concentrations of interleukin 2 (IL-2), IL-6, and tumor necrosis factor alpha (TNF-alpha) in serum and the ratio of CD4' T cell/CD8+ T cell in venous blood were measured before injection, at 1 week and 2 weeks after injection.There was no significant difference in the concentration of IL-2 between before and after injection in the same group (P=0.241), and between groups (P = 0.055). The concentration of IL-6 after injection was significantly lower than that before injection in the same group (P = 0.040), but no significant difference was found between groups (P = 0.357). The concentration of TNF-a showed no significant difference between before and after injection in the same group (P = 0.925), but the concentration of TNF-a in group B was significantly higher than that in groups A and C (P < 0.05). The ratio of CD4+ T cell/CD8+ T cell of venous blood had no significant difference between before and after operation in the same group (P = 0.248), and between groups (P=0.646).The freezing periosteum and bone marrow are lowly immunogenic. In order to decrease the immunogenicity of the joint, preserving the periosteum and removing the marrow cavity are recommended.
- The "neurovascular unit approach" to evaluate mechanisms of dysfunctional autoregulation in asphyxiated newborns in the era of hypothermia therapy. [REVIEW]
- Early Hum Dev 2014 Jul 22.
Despite improvements in obstetrical and neonatal care, and introduction of hypothermia as a neuroprotective therapy, perinatal brain injury remains a frequent cause of cerebral palsy, mental retardation and epilepsy. The recognition of dysfunction of cerebral autoregulation is essential for a real time measure of efficacy to identify those who are at highest risk for brain injury. This article will focus on the "neurovascular unit" approach to the care of asphyxiated neonates and will address 1) potential mechanisms of dysfunctional cerebral blood flow (CBF) regulation, 2) optimal monitoring methodology such as NIRS (near infrared spectroscopy), and TCD (transcutaneous Doppler), and 3) clinical implications of monitoring in the neonatal intensive care setting in asphyxiated newborns undergoing hypothermia and rewarming. Critical knowledge of the functional regulation of the neurovascular unit may lead to improved ability to predict outcomes in real time during hypothermia, as well as differentiate non-responders who might benefit from additional therapies.
- Two case studies and a review of paroxysmal cold hemoglobinuria. [Journal Article]
- Lab Med 2014; 45(3):253-8.
Paroxysmal cold hemoglobinuria (PCH) is an acquired hemolytic anemia caused by immunoglobulin G (IgG) antibodies that sensitize red blood cells (RBCs) at cold temperatures by fixing complement to the RBCs causing intravascular hemolysis on rewarming. PCH usually appears in young children as recurrent high fevers, chills, and passage of red-brown urine. The diagnostic test for PCH is the Donath-Landsteiner test, an in vitro assay for biphasic hemolysis. Herein, we present 2 cases of PCH that occurred within 12 months of each other. We quickly diagnosed the second case and treated the patient successfully, in part due to our recognition of its characteristics based on the first case. PCH is a hemolytic anemia for which there is a specific diagnostic test; the timely recognition of this entity by physicians and laboratory staff will allow prompt, supportive therapy and will raise the odds of quick resolution of hemolysis.
- Plasma proteomic changes during hypothermic and normothermic cardiopulmonary bypass in aortic surgeries. [JOURNAL ARTICLE]
- Int J Mol Med 2014 Jul 15.
Deep hypothermic circulatory arrest (DHCA) is a protective method against brain ischemia in aortic surgery. However, the possible effects of DHCA on the plasma proteins remain to be determined. In the present study, we used novel high‑throughput technology to compare the plasma proteomes during DHCA (22˚C) with selective cerebral perfusion (SCP, n=7) to those during normothermic cardiopulmonary bypass (CPB, n=7). Three plasma samples per patient were obtained during CPB: T1, prior to cooling; T2, during hypothermia; T3, after rewarming for the DHCA group and three corresponding points for the normothermic group. A proteomic analysis was performed using isobaric tag for relative and absolute quantification (iTRAQ) labeling tandem mass spectrometry to assess quantitative protein changes. In total, the analysis identified 262 proteins. The bioinformatics analysis revealed a significant upregulation of complement activation at T2 in normothermic CPB, which was suppressed in DHCA. These findings were confirmed by the changes of the terminal complement complex (SC5b‑9) levels. At T3, however, the level of SC5b‑9 showed a greater increase in DHCA compared to normothermic CPB, while 48 proteins were significantly downregulated in DHCA. The results demonstrated that DHCA and rewarming potentially exert a significant effect on the plasma proteome in patients undergoing aortic surgery.
- Induced Hypothermia During Resuscitation From Hemorrhagic Shock Attenuates Microvascular Inflammation In The Rat Mesenteric Microcirculation. [JOURNAL ARTICLE]
- Shock 2014 Jul 18.
Microvascular inflammation occurs during resuscitation following hemorrhagic shock, causing multiple organ dysfunction and mortality. Pre-clinical evidence suggests that hypothermia may have some benefit in selected patients by decreasing this inflammation, but this effect has not been extensively studied.Intravital microscopy was used to visualize mesenteric venules of anesthetized rats in real time to evaluate leukocyte adherence and mast cell degranulation. Animals were randomly allocated to normotensive or hypotensive groups, and further subdivided into hypothermic and normothermic resuscitation (N=6 per group). Animals in the shock groups underwent mean arterial blood pressure reduction to 40-45 mmHg for 1 hour via blood withdrawal. During the first two hours following resuscitation by infusion of shed blood plus double that volume of normal saline, rectal temperature of the hypothermic groups were maintained at 32-34°C, while the normothermic groups were maintained between 36-38°C. The hypothermic group was then rewarmed for the final two hours of resuscitation.Leukocyte adherence was significantly lower after 2 hours of hypothermic resuscitation compared with normothermic resuscitation: (2.8±0.8 vs 8.3±1.3 adherent leukocytes, p=0.004). Following rewarming, leukocyte adherence remained significantly different between hypothermic and normothermic shock groups: (4.7±1.2 vs 9.5±1.6 adherent leukocytes, p=0.038). Mast cell degranulation index (MDI) was significantly decreased in the hypothermic (1.02±0.04 MDI) vs normothermic (1.22±0.07 MDI) shock groups (p=0.038) after the experiment.Induced hypothermia during resuscitation following hemorrhagic shock attenuates microvascular inflammation in rat mesentery. Furthermore, this decrease in inflammation is carried over after rewarming takes place.
- Extracorporeal-Assisted Rewarming in the Management of Accidental Deep Hypothermic Cardiac Arrest: A Systematic Review of the Literature. [REVIEW]
- Heart Lung Circ 2014 Jun 27.
A systematic review of the literature surrounding the use of Extra-Corporeal Assisted Rewarming (ECAR) in patients presenting with deep hypothermia or hypothermic cardiac arrest was undertaken using a structured protocol. Thirty-one papers were deemed suitable for review, 13 of these were of sufficient quality to permit systematic data analysis. The primary outcome measure was survival to hospital discharge. The secondary outcome measure was functional neurological status at last follow-up. Analysis revealed a 67.7% survival to discharge and a 61.5% rate of good neurological recovery for patients presenting with pure hypothermic cardiac arrest. This was in marked contrast to a 23.4% survival and a 9.4% rate of good neurological outcome in those presenting with a mixed hypoxic/hypothermic arrest. Other data revealed a survival benefit for patients presenting with deep hypothermia without cardiac arrest treated with ECAR compared to those treated with conventional rewarming techniques. Hypoxic arrest, serum potassium >10mmol/L and presenting rhythm of asystole were found likely be significant predictors of poor outcome. Innovative reperfusion and rewarming strategies are also reviewed.
- Hand temperature responses to local cooling after a 10-day confinement to normobaric hypoxia with and without exercise. [JOURNAL ARTICLE]
- Scand J Med Sci Sports 2014 Jul 15.
The study examined the effects of a 10-day normobaric hypoxic confinement (FiO2 : 0.14), with [hypoxic exercise training (HT); n = 8)] or without [hypoxic ambulatory (HA; n = 6)] exercise, on the hand temperature responses during and after local cold stress. Before and after the confinement, subjects immersed their right hand for 30 min in 8 °C water [cold water immersion (CWI)], followed by a 15-min spontaneous rewarming (RW), while breathing either room air (AIR), or a hypoxic gas mixture (HYPO). The hand temperature responses were monitored with thermocouples and infrared thermography. The confinement did not influence the hand temperature responses of the HA group during the AIR and HYPO CWI and the HYPO RW phases; but it impaired the AIR RW response (-1.3 °C; P = 0.05). After the confinement, the hand temperature responses were unaltered in the HT group throughout the AIR trial. However, the average hand temperature was increased during the HYPO CWI (+0.5 °C; P ≤ 0.05) and RW (+2.4 °C; P ≤ 0.001) phases. Accordingly, present findings suggest that prolonged exposure to normobaric hypoxia per se does not alter the hand temperature responses to local cooling; yet, it impairs the normoxic RW response. Conversely, the combined stimuli of continuous hypoxia and exercise enhance the finger cold-induced vasodilatation and hand RW responses, specifically, under hypoxic conditions.
- Hyperglycemia and Insulin Resistance in Cardiac Arrest Patients Treated with Moderate Hypothermia. [JOURNAL ARTICLE]
- J Clin Endocrinol Metab 2014 Jul 17.:jc20141449.
Context: It is unknown whether the hyperglycemia that follows cardiac arrest and during therapeutic hypothermia (TH) is due to the arrest or the TH, whether it is associated with adverse outcomes or whether its treatment affects outcomes. Objective: To determine the effects of TH on blood glucose (BG) levels in post-cardiac arrest patients and the effects of hyperglycemia on mortality. Design: Chart review of 62 patients undergoing TH after cardiac arrest between September, 2005 and April, 2008. BG levels from 72 hours before arrest to 48 hours after TH and IV insulin infusion rates were analyzed and correlated with survival to discharge from hospital. Setting: Tertiary, university referral center. Patients: Patients undergoing TH after cardiac arrest. Interventions: TH consisted of cooling as rapidly as possible to 33°C, holding that temperature for 24 hours, and then controlled rewarming to 37°C over 8 or 16 hours. Hyperglycemia was managed with intravenous insulin drip protocols. Main Outcome Measure: The relationship of cardiac arrest and hypothermia to hyperglycemia with a key secondary outcome being the relationship of hyperglycemia to survival to discharge. Results: Analysis of glucose patterns showed no independent effect of TH on BG levels. Mean BG levels between cardiac arrest and the initiation of hypothermia were higher in Non-survivors (253 ± 112 mg/dL, n=48) than in Survivors (192 ± 69 mg/dL, n=24, p=0.016). BG, insulin infusion rates and insulin resistance during hypothermia, during rewarming, and 24-48 hours after hypothermia were not significantly different between the two groups. Conclusions: In patients treated with TH, the TH had no independent effect on BG levels. Mortality was associated with increased BG levels after cardiac arrest but before initiation of TH or an insulin drip. Likely, it is the severity of stress from the cardiac arrest that causes the hyperglycemia in these patients.
- The Effects of Local and General Hypothermia on Temperature Profiles of the Central Nervous System Following Spinal Cord Injury in Rats. [JOURNAL ARTICLE]
- Ther Hypothermia Temp Manag 2014 Jul 14.
Local and general hypothermia are used to treat spinal cord injury (SCI), as well as other neurological traumas. While hypothermia is known to provide significant therapeutic benefits due to its neuroprotective nature, it is unclear how the treatment may affect healthy tissues or whether it may cause undesired temperature changes in areas of the body that are not the targets of treatment. We performed 2-hour moderate general hypothermia (32°C core) or local hypothermia (30°C spinal cord) on rats that had received either a moderate contusive SCI or laminectomy (control) while monitoring temperatures at three sites: the core, spinal cord, and cortex. First, we identified that injured rats that received general hypothermia exhibited larger temperature drops at the spinal cord (-3.65°C, 95% confidence intervals [CIs] -3.72, -3.58) and cortex (-3.64°C, CIs -3.73, -3.55) than uninjured rats (spinal cord: -3.17°C, CIs -3.24, -3.10; cortex: -3.26°C, CIs -3.34, -3.17). This was found due to elevated baseline temperatures in the injured group, which could be due to inflammation. Second, both general hypothermia and local hypothermia caused a significant reduction in the cortical temperature (-3.64°C and -1.18°C, respectively), although local hypothermia caused a significantly lower drop in cortical temperature than general hypothermia (p<0.001). Lastly, the rates of rewarming of the cord were not significantly different among the methods or injury groups that were tested; the mean rate of rewarming was 0.13±0.1°C/min. In conclusion, local hypothermia may be more suitable for longer durations of hypothermia treatment for SCI to reduce temperature changes in healthy tissues, including the cortex.