Measuring brain temperature while maintaining brain normothermia in patients with severe traumatic brain injury

The aim of this study was to evaluate the relationship between superficial temporal artery temperature (Tt), rectal temperature (Tr) and intracranial temperature (ICT) when attempting to keep the brain in a normothermic condition in patients with severe traumatic brain injury (TBI). We also compared the incidence of temperature gradient reversal in patients who survived (survivors) and patients who did not (non-survivors) and the difference in temperature gradient reversal between survivors and non-survivors. Tr is normally lower than and ICT and temperature gradient reversal, when Tr exceeds ICT, has been demonstrated to be an early sign of brain death. A total of 28 patients with severe TBI were enrolled retrospectively in our study between November 2008 and February 2010. Each patient’s Tt, Tr and ICT was recorded every hour for 4 days. Our results show that the frequency of brain hyperthermia in our participants (ICT > 38 °C) was 17.7%. Using a paired t-test and Bland-Altman plots, it was shown that a significant temperature difference existed between Tt, Tr and ICT (p < 0.001). The use of Spearman’s correlation method revealed that Tt, Tr and ICT were positively correlated (p < 0.001). Brain death occurred in five patients at a mean of 9.6 hours (range: 8-12 hours) after a temperature gradient reversal between Tt, Tr and ICT. Fisher’s exact test showed that there was a significant difference in the incidence of temperature gradient reversal between Tt, Tr and ICT in survivors and non-survivors (p < 0.001). We conclude that a significant temperature difference exists between Tt, Tr and ICT when maintaining brain normothermia. The daily practice of non-invasive Tt measurement may cause doctors to underestimate ICT; reversal of the ICT and Tt and/or Tr temperatures could be an early marker of a poor prognosis for patients with severe TBI.     

Low arterial pressure during cardiopulmonary bypass in piglets does not decrease fluid leakage

BACKGROUND: Cardiopulmonary bypass (CPB) is associated with increased fluid filtration occasionally leading to post-operative organ dysfunction. One of the factors determining fluid filtration is the capillary hydrostatic pressure which depends on arterial pressure, venous pressure and pre- to post-capillary resistance ratio. The purpose of this study was to assess whether lowering of the mean arterial pressure and/or the central venous pressure could reduce fluid extravasation during normothermic and hypothermic CPB. METHODS: Seven piglets were given nitroprusside to a mean arterial pressure of 35-40 mmHg during 60 min of normothermic and 90 min of hypothermic CPB (LP group). They were compared with a control group (C group, n = 7) without blood pressure interventions. Blood chemistry, net fluid balance, plasma volume, colloid osmotic pressure in plasma and interstitial fluid, intravascular protein masses, fluid extravasation rate and total tissue water content were measured or calculated. RESULTS: Mean arterial pressure was significantly lower in the LP group than in the C group during CPB. Plasma volume tended to increase in the LP group (P > 0.05), but remained essentially unchanged in the C group. Net fluid balance in the LP group was more positive than in the C group 30 min after CPB start [1.02 (0.15) vs. 0.56 (0.13) ml/kg/min (Mean (SEM) P < 0.05)]. Fluid extravasation rate tended to be higher in the LP group and total tissue water content of the gastrointestinal tract, left myocardium and skin was significantly elevated compared with the C group. CONCLUSION: During CPB, lowering of the mean arterial pressure using nitroprusside did not reduce fluid extravasation. On the contrary, the data may implicate an increase in edema formation during low pressure CPB.     

Practical recommendations for patient blood management and the reduction of perioperative transfusion in joint replacement surgery

Data from the Australian Better Safer Transfusion programme show that about one‐third of patients undergoing hip or knee arthroplasty receive perioperative blood transfusions, placing them at increased risk for adverse clinical outcomes. Other concerns associated with allogeneic blood transfusion include the quality of stored red cell concentrates, the cost of provision of blood and the predicted local demographics, which mean that fewer donors will need to support a greater number of recipients. In view of the multiple challenges associated with allogeneic blood transfusion and its provision, we developed practical management recommendations for perioperative bleeding in joint replacement surgery, based on available evidence and expert consensus opinion, that aim to promote a new, responsible approach to transfusion management. Key recommendations are as follows. Patients' medical health, including haemoglobin and iron levels, needs to be evaluated and optimized preoperatively. Anticoagulant and antiplatelet therapy should be stopped if possible, unless indicated for secondary cardiovascular prevention or coronary stent patency, in which case careful consideration is required. If substantial blood loss is anticipated, intraoperative management with antifibrinolytic agents is recommended for bleeding prophylaxis. Normothermia should be maintained. Pharmacological and non‐pharmacological measures are recommended for post‐operative thromboprophylaxis. A blood management programme should be instituted for haemodynamically stable patients.     

Role of erythrocytes in short‐term rewarming kidney perfusion after cold storage

Short term normothermic reconditioning by machine perfusion after cold storage has shown beneficial effects in renal transplantation models. Systematic investigations concerning the inclusion of washed erythrocytes as oxygen carriers are lacking in this context. Porcine kidneys were subjected to 20 h of static cold storage. Prior to reperfusion, grafts were put on a machine for 2 h of oxygenated (95% O₂; 5% CO₂) rewarming perfusion. In one group (n = 6) washed erythrocytes were added to the perfusate after temperature has reached 20°C; the other group (n = 6) was run without additives. Control kidneys (n = 6) were immediately reperfused without treatment. Upon reperfusion in vitro, a more than twofold improvement of renal clearance of creatinine, urinary protein loss, fractional excretion of sodium, efficiency of oxygen utilization (TNa/VO₂) and a significant reduction of innate immune activation (HMGB1, tenascin C, expression of TLR4) was seen after machine perfusion, compared with the controls. However, no advantage could be obtained by the addition of erythrocytes and inner cortical tissue pO₂ always remained above normal values during cell‐free machine perfusion. Our data strongly argue in favor of a rewarming perfusion of cold stored donor kidneys but do not substantiate an indication for adding oxygen carriers in this particular setting.     

In-vivo and ex-vivo renal preservation

Summary A new renal perfusate of modified intracellular electrolyte composition made hyperosmolar with mannitol and requiring no additional additives was successfully used to preserve canine kidneys ex-vivo for 48 hours by initial perfusion and hypothermic storage. The new perfusate was also successful in protecting totally ischemic canine kidneys from the lethal effect of two-hours of normothermic exposure in-vivo. — The preservation technique is uncomplicated, the materials involved are inexpensive, and the preservation apparatus is readily transportable.Supported by the Max Kade Foundation, New York, New York.     

High-flow total body perfusion with severe hemodilution and normothermia in infants weighing less than 10 kg—Safe limits of hemodilution in cardiopulmonary bypass in infants

Cardiopulmonary bypass with 17 to 57 per cent dilution of hemoglobin for repair of ventricular septal defect (VSD) was applied to 26 infants weighing less than 10 kg at normal temperature. The higher flow rate was required to compensate the reduced oxygen carrying capacity and to maintain an adequate arterial pressure in proportion to a decrease of hemoglobin value. Perfusion index resulted in 3.0 to 6.5 L/m²/min in this series. When the dilution ratio of hemoglobin became more than 50 per cent and high flow rate was required, however, oxygen transfer ratio decreased remarkably on account of inadequate oxygen delivery and impaired venous return. In these cases, it was difficult to remove the diluent immediately after the operation in spite of powerful diuretic therapy. The results of the present study indicate that the safe limits of hemodilution is 50 per cent in cardiopulmonary bypass at normal temperature in infants.     

Normothermia in Arthroplasty

Background

Since the initial design of surgical theatres, the thermal environment of the operating suite itself has been an area of concern and robust discussion. In the 1950s, correspondence in the British Medical Journal discussed the most suitable design for a surgeon's cap to prevent sweat from dripping onto the surgical field. These deliberations stimulated questions about the effects of sweat-provoking environments on the efficiency of the surgical team, not to mention the effects on the patient. Although these benefits translate to implant-based orthopedic surgery, they remain poorly understood and, at times, ignored.

中低温减少体外循环下瓣膜置换术中丙泊酚剂量研究

目的以脑电频谱指数(BIS)为参考,探讨不同温度体外循环(CPB)下行瓣膜置换术患者丙泊酚的合适剂量。方法选择60例ASAⅡ-Ⅲ级择期行瓣膜置换术患者,根据术中最低鼻咽温分为2组:浅低温组(32℃,n=30)和中低温组(28℃,n=30)。术中调整丙泊酚剂量,保持BIS值处于40～60。分别于转机前(T1)、阻断升主动脉前(T2)、阻断升主动脉(T3)、开放升主动脉(T4)和停机后(T5)5个时间点,记录患者BIS值和丙泊酚剂量。结果患者均存活出院。组N患者转机前、停机后丙泊酚剂量分别为(4.6±1.3)mg/kg.hr和(4.3±1.6)mg/kg.hr,组H分别为(4.3±1.3)mg/kg.hr和(4.0±1.5)mg/kg.hr,差异均无统计学意义(P>0.05)。CPB转机开始后2组丙泊酚用量均较转机前明显减少,差异具有统计学意义(组N为2.4±1.2 mg/kg.hr,组H为1.2±0.5mg/kg.hr,P<0.01)。T3时间点中低温组较浅低温组下降明显,差异具有统计学意义(P<0.01)。无1例发生术中知晓现象。结论中低温CPB下行瓣膜置换术时,转机开始后应适量减少丙泊酚剂量。     

Efficacy of a Novel Prophylactic Barbiturate Therapy for Severe Traumatic Brain Injuries: Step-down Infusion of a Barbiturate with Normothermia

This study aimed to examine the beneficial effects of a novel prophylactic barbiturate therapy, step-down infusion of barbiturates, using thiamylal with normothermia (NOR+sdB), on the poor outcome in the patients with severe traumatic brain injuries (sTBI), in comparison with mild hypothermia (MD-HYPO). From January 2000 to March 2019, 4133 patients with TBI were admitted to our hospital. The inclusion criteria were: a Glasgow coma scale (GCS) score of ≤8 on admission, age between 20 and 80 years, intracranial hematoma requiring surgical evacuation of the hematoma with craniotomy and/or external decompression, and patients who underwent management of body temperature and assessed their outcome at 6–12 months. Finally, 43 patients were included in the MD-HYPO (n = 29) and NOR+sdB (n = 14) groups. sdB was initiated intraoperatively or immediately after the surgical treatment. There were no significant differences in patient characteristics, including age, sex, past medical history, GCS on admission, type of intracranial hematoma, and length of hospitalization between the two groups. Although NOR+sdB could not improve the patient’s poor outcome either at discharge from the intensive care unit (ICU) or at 6–12 months after admission, the treatment inhibited composite death at discharge from the ICU. The mean value of the maximum intracranial pressure (ICP) in the NOR+sdB group was <20 mmHg throughout the first 120 h. NOR+sdB prevented composite death in the ICU in patients with sTBI, and we may obtain novel insights into the beneficial role of prophylactic barbiturate therapy from suppression of the elevated ICP during the first 120 h.     

Relationship between prolonged neural suppression and cerebral hemodynamic dysfunction during hypothermia in asphyxiated piglets

Objectives

Hypothermia (HT) improves the outcome of neonatal hypoxic-ischemic encephalopathy. Here, we investigated changes during HT in cortical electrical activity using amplitude-integrated electroencephalography (aEEG) and in cerebral blood volume (CBV) and cerebral hemoglobin oxygen saturation using near-infrared time-resolved spectroscopy (TRS) and compared the results with those obtained during normothermia (NT) after a hypoxic-ischemic (HI) insult in a piglet model of asphyxia. We previously reported that a greater increase in CBV can indicate greater pressure-passive cerebral perfusion due to more severe brain injury and correlates with prolonged neural suppression during NT. We hypothesized that when energy metabolism is suppressed during HT, the cerebral hemodynamics of brains with severe injury would be suppressed to a greater extent, resulting in a greater decrease in CBV during HT that would correlate with prolonged neural suppression after insult.