Urinary cytokines correlate with acute kidney injury in critically ill COVID-19 patients.

BACKGROUND: Acute kidney injury is common in COVID-19 patients admitted to the ICU. Urinary biomarkers are a non-invasive way of assaying renal damage, and so far, urinary cytokines are not fully investigated. The current study aimed to assess urinary cytokine levels in COVID-19 patients. METHODS: Urine was collected from COVID-19 patients (n = 29) in intensive care and compared to a preoperative group of patients (n = 9) with no critical illness. 92 urinary cytokines were analyzed in multiplex using the Olink Target 96 inflammation panel and compared to clinical characteristics, and urinary markers of kidney injury. RESULTS: There were strong correlations between proinflammatory cytokines and between urinary cytokines and urinary kidney injury markers in 29 COVID-19 patients. Several cytokines were correlated to kidney injury, 31 cytokines to AKI stage and 19 cytokines correlated to maximal creatinine. CONCLUSIONS: Urinary inflammatory cytokines from a wide range of immune cell lineages were significantly upregulated during COVID-19 and the upregulation correlated with acute kidney injury as well as urinary markers of kidney tissue damage.

Inadequate prophylactic effect of low-molecular weight heparin in critically ill COVID-19 patients.

PURPOSE: The aim of this study was to investigate potential markers of coagulopathy and the effects of thromboprophylaxis with low-molecular-weight heparin (LMWH) on thromboelastography (TEG) and anti-factor Xa in critically ill COVID-19 patients. MATERIAL AND METHODS: We conducted a prospective study in 31 consecutive adult intensive care unit (ICU) patients. TEG with and without heparinase and anti-factor Xa analysis were performed. Standard thromboprophylaxis was given with dalteparin (75-100 IU/kg subcutaneously). RESULTS: Five patients (16%) had symptomatic thromboembolic events. All patients had a maximum amplitude (MA) > 65 mm and 13 (42%) had MA > 72 mm at some point during ICU stay. Anti-factor Xa activity were below the target range in 23% of the patients and above target range in 46% of patients. There was no significant correlation between dalteparin dose and anti-factor Xa activity. CONCLUSIONS: Patients with COVID-19 have hypercoagulability with high MA on TEG. The effect of LMWH on thromboembolic disease, anti-factor Xa activity and TEG was variable and could not be reliably predicted. This indicates that standard prophylactic doses of LMWH may be insufficient. Monitoring coagulation and the LMWH effect is important in patients with COVID-19 but interpreting the results in relation to risk of thromboembolic disease poses difficulties.

Coronary angiographic findings after cardiac arrest in relation to ECG and comorbidity.

INTRODUCTION: The relations between specific ECG patterns and coronary angiographic findings in cardiac arrest patients with different comorbidities are not properly assessed. More evidence is needed to identify patients with the highest risk for acute coronary artery disease as a cause of the cardiac arrest. This study aims to describe the coronary artery findings after cardiac arrest in relation to ECG and comorbidity. METHOD: A retrospective study of out-of-hospital cardiac arrest patients, with coronary angiography performed within 28 days. ECG on admission, comorbidity, PCI attempts and angiographic findings are described. Data were retrieved from national registries in Sweden. RESULTS: Among 1133 patients with available ECG and angiography information the mean age was 64 years. The rate of shockable rhythm was 79%. The total incidence of any significant stenosis in cardiac arrest patients without ST-elevation who underwent coronary angiography within 28 days was 71%. The incidence of any stenosis in patients with normal ECG was 62.1% and in patients with LBBB, 59.3%. In patients with ST-depression or RBBB, PCI attempts were made in 47.1% and 42.4% respectively, compared with 33.3% in patients with normal ECG. Among patients without ST-elevation, those with diabetes mellitus and those with initial shockable rhythm respectively, 84.8% and 71.5 had at least one significant stenosis. CONCLUSION: Our study suggests, that evaluation of ECG patterns and comorbidities in out-of-hospital cardiac arrest patients without ST-segment elevation may be important to identify those with a high risk of coronary artery lesions that could benefit from early revascularization.

Characteristics of jugular bulb oxygen saturation in patients after cardiac arrest: A prospective study.

BACKGROUND: Using cerebral oxygen venous saturation post-cardiac arrest (CA) is limited because of a small sample size and prior to establishment of target temperature management (TTM). We aimed to describe variations in jugular bulb oxygen saturation during intensive care in relation to neurological outcome at 6 months post- CA in cases where TTM 33°C was applied. METHOD: Prospective observational study in patients over 18 years, comatose immediately after resuscitation from CA. Patients were treated with TTM 33°C M and received a jugular bulb catheter within the first 26 hours post-CA. Neurological outcome was assessed at 6 months using the Cerebral Performance Categories (CPC) and dichotomized into good (CPC 1-2) and poor outcome (CPC 3-5). RESULTS: Seventy-five patients were included and 37 (49%) patients survived with a good outcome at 6 months post-CA. No differences were found between patients with good outcome and poor outcome in jugular bulb oxygen saturation. Higher values were seen in differences in oxygen content between central venous oxygen saturation and jugular bulb oxygen saturation in patients with good outcome compared to patients with poor outcome at 6 hours (12 [8-21] vs 5 [-0.3 to 11]% P = .001) post-CA. Oxygen extraction fraction from the brain illustrated lower values in patients with poor outcome compared to patients with good outcome at 96 hours (14 [9-23] vs 31 [25-34]% P = .008). CONCLUSIONS: Oxygen delivery and extraction differed in patients with a good outcome compared to those with a poor outcome at single time points. Based on the present findings, the usefulness of jugular bulb oxygen saturation for prognostic purposes is uncertain in patients treated with TTM 33°C post-CA.

Acute brain lesions on magnetic resonance imaging in relation to neurological outcome after cardiac arrest.

BACKGROUND: Magnetic resonance imaging (MRI) of the brain including diffusion-weighted imaging (DWI) is reported to have high prognostic accuracy in unconscious post-cardiac arrest (CA) patients. We documented acute MRI findings in the brain in both conscious and unconscious post-CA patients treated with target temperature management (TTM) at 32-34°C for 24 h as well as the relation to patients' neurological outcome after 6 months. METHODS: A prospective observational study with MRI was performed regardless of the level of consciousness in post-CA patients treated with TTM. Neurological outcome was assessed using the Cerebral Performance Categories scale and dichotomized into good and poor outcome. RESULTS: Forty-six patients underwent MRI at 3-5 days post-CA. Patients with good outcome had minor, mainly frontal and parietal, lesions. Acute hypoxic/ischemic lesions on MRI including DWI were more common in patients with poor outcome (P = 0.007). These lesions affected mostly gray matter (deep or cortical), with or without involvement of the underlying white matter. Lesions in the occipital and temporal lobes, deep gray matter and cerebellum showed strongest associations with poor outcome. Decreased apparent diffusion coefficient, was more common in patients with poor outcome. CONCLUSIONS: Extensive acute hypoxic/ischemic MRI lesions in the cortical regions, deep gray matter and cerebellum detected by visual analysis as well as low apparent diffusion coefficient values from quantitative measurements were associated with poor outcome. Patients with good outcome had minor hypoxic/ischemic changes, mainly in the frontal and parietal lobes.

Epidermal exfoliation of over 95% after a burn in an 18-month-old boy: Case report and review of the literature.

This report concerns an 18-month-old boy who presented with a 6% total body surface area scald. The subject of this report is unique in that he developed the largest exfoliation described in literature. After 3 days an epidermal exfoliation with the appearance of a deliberately inflicted scald developed. As the exfoliation progressed to over 95% total body surface area the suspicion of child abuse or neglect could be abandoned. The diagnosis Staphylococcal scalded skin syndrome was set, due to the finding of Staphylococcus aureus on swabs, the lack of mucosal engagement, and the patient's age. The boy's skin healed within 3 weeks. The few reports published are all case reports and most frequently described visually infected burns with smaller epidermal exfoliations, and clinically based exfoliation diagnosis. S. aureus often cause burn wound infections that can lead to complications caused by cross-infection. It is important for burn surgeons and intensive care specialists to be aware of the increased possibility of Staphylococcal scalded skin syndrome occurring in patients who have a reduced barrier to infection such as burn patients and also, that the diagnosis can be difficult to make.

CPR-related injuries after manual or mechanical chest compressions with the LUCAS™ device: a multicentre study of victims after unsuccessful resuscitation.

AIM: The reported incidence of injuries due to cardiopulmonary resuscitation using manual chest compressions (manual CPR) varies greatly. Our aim was to elucidate the incidence of CPR-related injuries by manual chest compressions compared to mechanical chest compressions with the LUCAS device (mechanical CPR) in non-survivors after out-of-hospital cardiac arrest. METHODS: In this prospective multicentre trial, including 222 patients (83 manual CPR/139 mechanical CPR), autopsies were conducted after unsuccessful CPR and the results were evaluated according to a specified protocol. RESULTS: Among the patients included, 75.9% in the manual CPR group and 91.4% in the mechanical CPR group (p=0.002) displayed CPR-related injuries. Sternal fractures were present in 54.2% of the patients in the manual CPR group and in 58.3% in the mechanical CPR group (p=0.56). Of the patients in the manual CPR group, there were 64.6% with at least one rib fracture versus 78.8% in the mechanical CPR group (p=0.02). The median number of rib fractures among patients with rib fractures was 7 in the manual CPR group and 6 in the mechanical CPR group. No CPR-related injury was considered to be the cause of death. CONCLUSION: In patients with unsuccessful CPR after out-of-hospital cardiac arrest, rib fractures were more frequent after mechanical CPR but there was no difference in the incidence of sternal fractures. No injury was deemed fatal by the pathologist.

High-frequency jet ventilation shortened the duration of gas embolization during laparoscopic liver resection in a porcine model.

BACKGROUND: Positive pressure mechanical ventilation causes rhythmic changes in thoracic pressure and central blood flow. If entrainment occurs, it could be easier for carbon dioxide to enter through a wounded vein during laparoscopic liver lobe resection (LLR). High-frequency jet ventilation (HFJV) is a ventilating method that does not cause pronounced pressure or blood flow changes. This study aimed to investigate whether HFJV could influence the frequency, severity, or duration of gas embolism (GE) during LLR. METHODS: Twenty-four anaesthetized piglets underwent lobe resection and were randomly assigned to either normal frequency ventilation (NFV) or HFJV (n=12 per group). During resection, a standardized injury to the left hepatic vein was created to increase the risk of GE. Haemodynamic and respiratory variables were monitored. Online blood gas monitoring and transoesophageal echocardiography were used. GE occurrence and severity were graded as 0 (none), 1 (minor), or 2 (major), depending on the echocardiography results. RESULTS: GE duration was shorter in the HFJV group (P=0.008). However, no differences were found between the two groups in the frequency or severity of embolism. Incidence of Grade 2 embolism was less than that found in previous studies and physiological responses to embolism were variable. CONCLUSION: HFJV shortened the mean duration of GE during LLR and was a feasible ventilation method during the procedure. Individual physiological responses to GE were unpredictable.

Elevated PEEP without effect upon gas embolism frequency or severity in experimental laparoscopic liver resection.

BACKGROUND: Carbon dioxide (CO(2)) embolism is a potential complication in laparoscopic liver surgery. Gas embolism (GE) is thought to occur when central venous pressure (CVP) is lower than the intra-abdominal pressure (IAP). This study aimed to investigate whether an increased CVP due to induction of PEEP could influence the frequency and severity of GE during laparoscopic liver resection. METHODS: Twenty anaesthetized piglets underwent laparoscopic left liver lobe resection and were randomly assigned to either 5 or 15 cm H(2)O PEEP (n=10 per group). During resection, a standardized injury to the left hepatic vein [venous cut (VC)] was created to increase the risk of GE. Haemodynamic and respiratory variables were monitored, and online arterial blood gas monitoring and transoesophageal echocardiography (TOE) were used. The occurrence and severity of embolism was graded as 0 (none), 1 (minor), or 2 (major), depending on the TOE results. RESULTS: No differences were found between the two groups regarding the frequency or severity of GE, during either the VC (P=0.65) or the rest of the surgery (P=0.24). GE occurred irrespective of the CVP-IAP gradient. CONCLUSIONS: Mechanisms other than the CVP-IAP gradient seemed during laparoscopic liver surgery to contribute to the formation of CO(2) embolism. This is of clinical importance to the anaesthetists.

Plasma tau protein in comatose patients after cardiac arrest treated with therapeutic hypothermia.

BACKGROUND: Neurological outcome after cardiac arrest (CA) is difficult to predict in the acute phase. In this pilot study, we assessed blood levels of tau protein as a prognostic marker for the neurological outcome after 6 months in patients treated with hypothermia after resuscitation from CA. METHODS: 22 unconscious patients resuscitated after CA were treated with mild hypothermia (32-34°C) for 26 h. Blood samples were collected at 2, 6, 12, 24, 48, and 96 h after CA, and the concentration of tau protein was analyzed. Neurological outcome was assessed with the Glasgow-Pittsburgh cerebral performance category (CPC) scale at intensive care unit (ICU) discharge and after 6 months. The higher of the two CPC scores was used. RESULTS: At ICU discharge, 21/22 patients were alive, of whom 10 had a good (CPC 1-2) outcome. After 6 months, 15/22 patients were alive, of whom 14 had a good outcome. Tau protein levels were higher among those with a poor outcome at 48 h and 96 h. At 96 h sampling, tau concentration predicted a poor outcome (CPC 3-5) with a sensitivity of 71% and a specificity of 93%. CONCLUSIONS: Although in a pilot study, a late increase in plasma tau protein seems to be associated with a worse outcome after hypothermia treatment after CA, although more studies are needed.

Brain temperature in volunteers subjected to intranasal cooling.

PURPOSE: Intranasal cooling can be used to initiate therapeutic hypothermia. However, direct measurement of brain temperature is difficult and the intra-cerebral distribution of temperature changes with cooling is unknown. The purpose of this study was to measure the brain temperature of human volunteers subjected to intranasal cooling using non-invasive magnetic resonance (MR) methods. METHODS: Intranasal balloons catheters circulated with saline at 20°C were applied for 60 min in ten awake volunteers. No sedation was used. Brain temperature changes were measured and mapped using MR spectroscopic imaging (MRSI) and phase-mapping techniques. Heart rate and blood pressure were monitored throughout the experiment. Rectal temperature was measured before and after the cooling. Mini Mental State Examination (MMSE) test and nasal inspection were done before and after the cooling. Questionnaires about the subjects' personal experience were completed after the experiment. RESULTS: Brain temperature decrease measured by MRSI was -1.7 ± 0.8°C and by phase-mapping -1.8 ± 0.9°C (n = 9) at the end of cooling. Spatial distribution of temperature changes was relatively uniform. Rectal temperature decreased by -0.5 ± 0.3°C (n = 5). The physiological parameters were stable and no shivering was reported. The volunteers remained alert during cooling and no cognitive dysfunctions were apparent in the MMSE test. Postcooling nasal examination detected increased nasal secretion in nine of the ten volunteers. Volunteers' acceptance of the method was good. CONCLUSION: Both MR techniques revealed brain temperature reductions after 60 min of intranasal cooling with balloons circulated with saline at 20°C in awake, unsedated volunteers.

High intra-abdominal pressure during experimental laparoscopic liver resection reduces bleeding but increases the risk of gas embolism.

BACKGROUND: Various recommendations exist regarding intra-abdominal pressure (IAP) during laparoscopic liver resection. A high IAP may reduce bleeding but at the same time increase the risk of gas embolism. This study investigated the effects of two different IAPs during laparoscopic left liver lobe resection in piglets. METHODS: Sixteen piglets underwent laparoscopic left liver lobe resection using carbon dioxide pneumoperitoneum of either 8 or 16 mmHg (8 per group). A combination of CUSA System 200™ and LigaSure™ instruments was used for parenchymal division. During resection, a standard injury to the left liver vein was also created to increase the risk of bleeding and/or gas embolism during the operation. Heart rate, cardiac output, and arterial, pulmonary arterial, pulmonary capillary wedge and central venous pressures were measured. Arterial blood gases were monitored continuously. Transoesophageal echocardiography was video recorded to detect and quantify gas embolism within the right cardiac ventricle. The duration of operation and bleeding were noted. RESULTS: High IAP resulted in reduced bleeding (P = 0·016), but gas embolism occurred more frequently (P = 0·001) than with low IAP. Gas embolism disturbed gas exchange, with an increase in arterial pressure of carbon dioxide, and a decrease in arterial partial pressure of oxygen and pH. These effects were sustained for at least 30 min after surgery. CONCLUSION: High IAP reduces the amount of bleeding but increases the risk of gas embolism. Monitoring for gas embolism is therefore indicated if a high IAP is used during laparoscopic liver resection.

Gas embolism during laparoscopic liver resection in a pig model: frequency and severity.

BACKGROUND: Laparoscopic liver surgery is evolving rapidly. Carbon dioxide embolism is a potential complication. The aim of this work was to study the frequency and severity of gas embolism (GE) during laparoscopic liver lobe resection in a pig model and the resulting cardiovascular and respiratory changes. METHODS: Fifteen anaesthetized piglets underwent laparoscopic left liver lobe resection. Haemodynamic and respiratory variables were monitored, including systemic and pulmonary arterial pressures, end-tidal CO2, and pulmonary dead space. Online blood gas monitoring and a transoesophageal echocardiography (TOE) were used. GE was graded semi-quantitatively as grade 0 (none), grade 1 (minor), or grade 2 (major), depending on the TOE results. RESULTS: In 10 of 15 piglets, GE occurred. In total, 33 separate episodes of GE were recorded. All 13 episodes of grade 2 and three of grade 1 were serious enough to cause mainly respiratory, but also haemodynamic effects. Mostly, grade 1 GE caused only minor respiratory or haemodynamic changes. Most variables were affected during grade 2 GE; the most important were Pa(o(2)), Pa(co(2)), end-tidal CO2, Vd/Vt, and mean pulmonary arterial pressure. CONCLUSIONS: GE occurred frequently during laparoscopic liver resection in this experimental study. Approximately half of the embolisms were serious enough to cause respiratory or haemodynamic disturbances or both. Pending further human studies, a combination of several monitoring techniques, with narrow limits for the alarm settings, will ensure correct interpretation of the complex physiological response to GE and reveal it early enough to alert the anaesthetist and the surgeon to the ongoing problem.

Sex differences in cerebral injury after severe haemorrhage and ventricular fibrillation in pigs.

BACKGROUND: Experimental studies of haemorrhagic shock have documented a superior haemodynamic response and a better outcome in female animals as compared with male controls. Such sexual dimorphism has, nevertheless, not been reported after circulatory arrest that follows exsanguination and shock. We aimed to study differences in cerebral injury markers after exsanguination cardiac arrest in pre-pubertal piglets. The hypothesis was that cerebral injury is less extensive in female animals, and that this difference is independent of sexual hormones or choice of resuscitative fluid. METHODS: Thirty-two sexually immature piglets (14 males and 18 females) were subjected to 5 min of haemorrhagic shock followed by 2 min of ventricular fibrillation and 8 min of cardiopulmonary resuscitation, using three resuscitation fluid regimens (whole blood, hypertonic saline and dextran, or acetated Ringers' solution plus whole blood and methylene blue). Haemodynamic values, cellular markers of brain injury and brain histology were studied. RESULTS: After successful resuscitation, female piglets had significantly greater cerebral cortical blood flow, tended to have lower S-100beta values and a lower cerebral oxygen extraction ratio. Besides, in female animals, systemic and cerebral venous acidosis were mitigated. Female piglets exhibited a significantly smaller increase in neuronal nitric oxide synthase (nNOS) and inducible nitric oxide synthase (iNOS) expression in their cerebral cortex, smaller blood-brain-barrier (BBB) disruption and significantly smaller neuronal injury. CONCLUSION: After resuscitation from haemorrhagic circulatory arrest, cerebral reperfusion is greater, and BBB permeability and neuronal injury is smaller in female piglets. An increased cerebral cortical iNOS and nNOS expression in males implies a mechanistic relationship with post-resuscitation neuronal injury and warrants further investigation.

Intranasal cooling with or without intravenous cold fluids during and after cardiac arrest in pigs.

BACKGROUND: Intranasal balloon catheters circulated with cold saline have previously been used for the induction and maintenance of selective brain cooling in pigs with normal circulation. In the present study, we investigated the feasibility of therapeutic hypothermia initiation, maintenance and rewarming using such intranasal balloon catheters with or without addition of intravenous ice-cold fluids during and after cardiac arrest treatment in pigs. MATERIAL AND METHODS: Cardiac arrest was induced in 20 anaesthetised pigs. Following 8 min of cardiac arrest and 1 min of cardiopulmonary resuscitation (CPR), cooling was initiated after randomisation with either intranasal cooling (N) or combined with intravenous ice-cold fluids (N+S). Hypothermia was maintained for 180 min, followed by 180 min of rewarming. Brain and oesophageal temperatures, haemodynamic variables and intracranial pressure (ICP) were recorded. RESULTS: Brain temperatures reductions after cooling did not differ (3.8 +/- 0.7 degrees C in the N group and 4.3 +/- 1.5 degrees C in the N+S group; P=0.47). The corresponding body temperature reductions were 3.6 +/- 1.2 degrees C and 4.6 +/- 1.5 degrees C (P=0.1). The resuscitation outcome was similar in both groups. Mixed venous oxygen saturation was lower in the N group after cooling and rewarming (P=0.024 and 0.002, respectively) as compared with the N+S group. ICP was higher after rewarming in the N group (25.2 +/- 2.9 mmHg; P=0.01) than in the N+S group (15.7 +/- 3.3 mmHg). CONCLUSIONS: Intranasal balloon catheters can be used for therapeutic hypothermia initiation, maintenance and rewarming during CPR and after successful resuscitation in pigs.

Outcome, timing and adverse events in therapeutic hypothermia after out-of-hospital cardiac arrest.

BACKGROUND: Therapeutic hypothermia (TH) after cardiac arrest protects from neurological sequels and death and is recommended in guidelines. The Hypothermia Registry was founded to the monitor outcome, performance and complications of TH. METHODS: Data on out-of-hospital cardiac arrest (OHCA) patients admitted to intensive care for TH were registered. Hospital survival and long-term outcome (6-12 months) were documented using the Cerebral Performance Category (CPC) scale, CPC 1-2 representing a good outcome and 3-5 a bad outcome. RESULTS: From October 2004 to October 2008, 986 TH-treated OHCA patients of all causes were included in the registry. Long-term outcome was reported in 975 patients. The median time from arrest to initiation of TH was 90 min (interquartile range, 60-165 min) and time to achieving the target temperature (< or =34 degrees C) was 260 min (178-400 min). Half of the patients underwent coronary angiography and one-third underwent percutaneous coronary intervention (PCI). Higher age, longer time to return of spontaneous circulation, lower Glasgow Coma Scale at admission, unwitnessed arrest and initial rhythm asystole were all predictors of bad outcome, whereas time to initiation of TH and time to reach the goal temperature had no significant association. Bleeding requiring transfusion occurred in 4% of patients, with a significantly higher risk if angiography/PCI was performed (2.8% vs. 6.2%P=0.02). CONCLUSIONS: Half of the patients survived, with >90% having a good neurological function at long-term follow-up. Factors related to the timing of TH had no apparent association to outcome. The incidence of adverse events was acceptable but the risk of bleeding was increased if angiography/PCI was performed.

Scandinavian clinical practice guidelines for therapeutic hypothermia and post-resuscitation care after cardiac arrest.

BACKGROUND AND AIM: Sudden cardiac arrest survivors suffer from ischaemic brain injury that may lead to poor neurological outcome and death. The reperfusion injury that occurs is associated with damaging biochemical reactions, which are suppressed by mild therapeutic hypothermia (MTH). In several studies MTH has been proven to be safe, with few complications and improved survival, and is recommended by the International Liaison of Committee on Resuscitation. The aim of this paper is to recommend clinical practice guidelines for MTH treatment after cardiac arrest from the Scandinavian Society of Anaesthesiology and Intensive Care Medicine (SSAI). METHODS: Relevant studies were identified after two consensus meetings of the SSAI Task Force on Therapeutic Hypothermia (SSAITFTH) and via literature search of the Cochrane Central Register of Controlled Trials and Medline. Evidence was assessed and consensus opinion was used when high-grade evidence (Grade of Recommendation, GOR) was unavailable. A management strategy was developed as a consensus from the evidence and the protocols in the participating countries. RESULTS AND CONCLUSION: Although proven beneficial only for patients with initial ventricular fibrillation (GOR A), the SSAITFTH also recommend MTH after restored spontaneous circulation, if active treatment is chosen, in patients with initial pulseless electrical activity and asystole (GOR D). Normal ethical considerations, premorbid status, total anoxia time and general condition should decide whether active treatment is required or not. MTH should be part of a standardized treatment protocol, and initiated as early as possible after indication and treatment have been decided (GOR E). There is insufficient evidence to make definitive recommendations among techniques to induce MTH, and we do not know the optimal target temperature, duration of cooling and rewarming time. New studies are needed to address the question as to how MTH affects, for example, prognostic factors.

Intracerebral monitoring in comatose patients treated with hypothermia after a cardiac arrest.

BACKGROUND: Induced mild hypothermia (32-34 degrees C) has proven to reduce ischemic brain injury and improve outcome after a cardiac arrest (CA). The aim of this investigation was to study the occurrence of increased intracranial pressure (ICP) and neurochemical metabolic changes indicating cerebral ischemia, after CA and cardiopulmonary resuscitation (CPR), when induced hypothermia was applied. METHODS: ICP, brain chemistry and brain temperature were monitored during induced hypothermia and re-warming in four adult unconscious patients with restoration of spontaneous circulation after CA and CPR. RESULTS: ICP was occasionally above 20 mmHg. Neurochemical changes indicating cerebral ischemia (increased lactate/pyruvate ratio) and excitoxicity (increased glutamate) were found after CA, and signs of ischemia were also observed during the re-warming phase. A biphasic increase in glycerol was seen, which may have been a result of both membrane degradation and overspill from the general circulation. CONCLUSIONS: Intracerebral microdialysis and ICP monitoring may be used in selected patients not requiring anticoagulants and PCI to obtain information regarding the common disturbances of intracranial dynamics after CA. The results of this study underline the importance of inducing hypothermia quickly after CA and emphasize the need for developing tools for guidance of the re-warming.

Intranasal selective brain cooling in pigs.

BACKGROUND: Special clinical situations where general hypothermia cannot be recommended but can be a useful treatment demand a new approach, selective brain cooling. The purpose of this study was to selectively cool the brain with cold saline circulating in balloon catheters introduced into the nasal cavity in pigs. MATERIAL AND METHODS: Twelve anaesthetised pigs were subjected to selective cerebral cooling for a period of 6 h. Cerebral temperature was lowered by means of bilaterally introduced nasal balloon catheters perfused with saline cooled by a heat exchanger to 8-10 degrees C. Brain temperature was measured in both cerebral hemispheres. Body temperature was measured in rectum, oesophagus and the right atrium. The pigs were normoventilated and haemodynamic variables were measured continuously. Acid-base and electrolyte status was measured hourly. RESULTS: Cerebral hypothermia was induced rapidly and within the first 20 min of cooling cerebral temperature was lowered from 38.1+/-0.6 degrees C by a mean of 2.8+/-0.6 to 35.3+/-0.6 degrees C. Cooling was maintained for 6 h and the final brain temperature was 34.7+/-0.9 degrees C. Concomitantly, the body temperature, as reflected by oesophageal temperature was decreased from 38.3+/-0.5 to 36.6+/-0.9 degrees C. No circulatory or metabolic disturbances were noted. CONCLUSIONS: Inducing selective brain hypothermia with cold saline via nasal balloon catheters can effectively be accomplished in pigs, with no major disturbances in systemic circulation or physiological variables. The temperature gradients between brain and body can be maintained for at least 6 h.

Laparoscopic parenchymal division of the liver in a porcine model: comparison of the efficacy and safety of three different techniques.

BACKGROUND: Bleeding is a known and CO2 embolization a suggested risk factor for increased morbidity after laparoscopic liver resection. Devices for laparoscopic liver parenchymal transection must be evaluated for safety in this context. METHOD: Twelve piglets underwent laparoscopic surgery during CO2 pneumoperitoneum, each animal receiving three 6 cm long transections into the liver parenchyma made with ultrasonic dissector, ultrasonic shears and vessel sealing system, respectively. Endpoints were bleeding, operation time and gas embolization. The transections and embolization events, evaluated with transesophageal echocardiography, were video recorded. Bleeding and embolization were also assessed on video tapes and operating time measured. Arterial blood gases were recorded on line. RESULTS: The ultrasonic dissector was least advantageous in terms of bleeding and operation time. Gas embolization was more frequent with the vessel sealing system than with the ultrasonic dissector and ultrasonic shears. During two episodes of gas embolization, pCO2 increased and pO2 and pH decreased. CONCLUSIONS: Use of all three devices is feasible. Bleeding and operation time are greatest with the ultrasonic dissector. Gas embolization occurs during transection, though in most instances it is completely harmless. Laparoscopic liver surgery with these techniques used may pose a risk of gas embolization with clinical implications. Monitoring for such events is probably to be recommended.