The incidence and significance of accidental hypothermia in major trauma--a prospective observational study

Background

Serious sequelae have been associated with injured patients who are hypothermic (<35 °C) including coagulopathy, acidosis, decreased myocardial contractility and risk of mortality.

Aim

Establish the incidence of accidental hypothermia in major trauma patients and identify causative factors.

Method

Prospective identification and subsequent review of 732 medical records of major trauma patients presenting to an Adult Major Trauma Centre was undertaken between January and December 2008. Multivariate analysis was performed using logistic regression. Significant and clinically relevant variables from univariate analysis were entered into multivariate models to evaluate determinants for hypothermia and for death. Goodness of fit was determined with the use of the Hosmer-Lemeshow statistic.

Main results

Overall mortality was 9.15%. The incidence of hypothermia was 13.25%. The mortality of patients with hypothermia was 29.9% with a threefold independent risk of death: OR (CI 95%) 3.44 (1.48-7.99), P = 0.04. Independent determinants for hypothermia were pre-hospital intubation: OR (CI 95%) 5.18 (2.77-9.71), P < 0.001, Injury Severity Score (ISS): 1.04 (1.01-1.06), P = 0.01, Arrival Systolic Blood Pressure (ASBP) < 100 mm Hg: 3.04 (1.24-7.44), P = 0.02, and wintertime: 1.84 (1.06-3.21), P = 0.03.Of the 87 hypothermic patients who had repeat temperatures recorded in the Emergency Department, 77 (88.51%) patients had a temperature greater than the recorded arrival temperature. There was no change in recorded temperature for four (4.60%) patients, whereas six (6.90%) patients were colder at Emergency Department discharge.

Conclusion

Seriously injured patients with accidental hypothermia have a higher mortality independent of measured risk factors. For patients with multiple injuries a coordinated effort by paramedics, nurses and doctors is required to focus efforts toward early resolution of hypothermia aiming to achieve a temperature >35 °C.     

Therapeutic hypothermia after cardiac arrest: A retrospective comparison of surface and endovascular cooling techniques

Objectives

Therapeutic hypothermia (32-34 °C) is recommended for comatose survivors of cardiac arrest; however, the optimal technique for cooling is unknown. We aimed to compare therapeutic hypothermia using either surface or endovascular techniques in terms of efficacy, complications and outcome.

Design

Retrospective cohort study.

Setting

Thirty-bed teaching hospital intensive care unit (ICU).

Patients

All patients (n = 83) undergoing therapeutic hypothermia following cardiac arrest over a 2.5-year period. The mean age was 61 ± 16 years; 88% of arrests occurred out of hospital, and 64% were ventricular fibrillation/tachycardia.

Interventions

Therapeutic hypothermia was initiated in the ICU using iced Hartmann's solution, followed by either surface (n = 41) or endovascular (n = 42) cooling; choice of technique was based upon endovascular device availability. The target temperature was 32-34 °C for 12-24 h, followed by rewarming at a rate of 0.25 °C h⁻¹.

Measurements and main results

Endovascular cooling provided a longer time within the target temperature range (p = 0.02), less temperature fluctuation (p = 0.003), better control during rewarming (0.04), and a lower 48-h temperature load (p = 0.008). Endovascular cooling also produced less cooling-associated complications in terms of both overcooling (p = 0.05) and failure to reach the target temperature (p = 0.04). After adjustment for known confounders, there were no differences in outcome between the groups in terms of ICU or hospital mortality, ventilator free days and neurological outcome.

Conclusion

Endovascular cooling provides better temperature management than surface cooling, as well as a more favorable complication profile. The equivalence in outcome suggested by this small study requires confirmation in a randomized trial.     

Survival does not improve when therapeutic hypothermia is added to post-cardiac arrest care

Background

We investigated whether the use of therapeutic hypothermia improves the outcome after cardiac arrest (CA) under routine clinical conditions.

Method

In a retrospective study, data of CA survivors treated from 2003 to 2010 were analysed. Of these, 143 patients were treated with hypothermia at 33 ± 0.5 °C for 24 h according to predefined inclusion criteria, while 67 who did not fulfil these criteria received comparable therapy without hypothermia.

Results

210 patients were included, 143 in the hypothermia group (HG) and 67 in the normothermia group (NG). There was no significant difference in mortality between the groups; 69 (48.2%) in the HG died in the first four weeks, compared to 30 patients (44.8%) in the NG (p = 0.659). Patients in the NG were older and more seriously ill, and CA occurred more often in-hospital. Binary logistic regression revealed ventricular fibrillation (p = 0.044), NSE serum level <33 ng ml⁻¹ (p < 0.001), age (p = 0.035) and witnessed cardiac arrest (p = 0.043) as independent factors significantly improving survival after CA, whereas hypothermia was not (p = 0.69). The target temperature was maintained for a significantly longer time (19.5 h vs. 15.2 h; p = 0.003) in hypothermia patients with a favourable outcome than in those with an unfavourable outcome.

Conclusion

There was no improvement in survival rates when hypothermia was added to standard therapy in this case series, as compared to standard therapy alone. The time at target temperature may be of relevance. We need better evidence in order to expand the recommendations for hypothermia after CA.     

Mild hypothermia reduces acute mortality and improves hemodynamic outcome in a cardiogenic shock pig model

Introduction

Cardiogenic shock is the main cause of death in patients hospitalized due to an acute myocardial infarction. Mild hypothermia reduces metabolism and could offer protective effects for this condition. The aim of our study was to investigate if mild therapeutic hypothermia would improve outcome and hemodynamic parameters in an ischemic cardiogenic shock pig model.

Methods

Twenty-five pigs (40-50 kg) were anesthetized and a normothermic temperature of 38 °C was established utilising an endovascular cooling catheter in a closed-chest model. A Swan-Ganz catheter was placed in the pulmonary artery. Hemodynamic parameters were continuously monitored and blood gases were sampled every 30 min. Ischemia was induced by inflation of a PCI balloon in proximal LAD for 40 min. Sixteen pigs that have fulfilled predefined shock criteria were randomized to hypothermia (n = 8), or normothermia (n = 8). Hypothermia (33 °C) was induced after onset of reperfusion by using an endovascular temperature modulating catheter and was maintained until termination of the experiment.

Results

The pigs in the hypothermia group were cooled to <34 °C in approximately 45 min. 5/8 pigs in the normothermia group died while all pigs in the hypothermia group survived (p < 0.01). Stroke volume and blood pressure were significantly higher in the hypothermia group (p < 0.05), whereas heart rate was significantly lower in the hypothermia group (p = 0.01). Cardiac output did not differ among the groups (p = 0.13). Blood gas analysis revealed higher mixed venous oxygen saturation, pH, and base excess in the hypothermia group indicating less development of metabolic acidosis (p < 0.05).

Conclusions

In this pig model, mild therapeutic hypothermia reduces acute mortality in cardiogenic shock, improves hemodynamic parameters and reduces metabolic acidosis. These findings suggest a possible clinical benefit of therapeutic hypothermia for patients with acute cardiogenic shock.     

Therapeutic hypothermia attenuates acute lung injury in paraquat intoxication in rats

Aim of the study

Paraquat intoxication induces acute lung injury and numerous fatalities have been reported. The mechanism of toxic effect of paraquat is oxidative injury and inflammation. Therapeutic hypothermia has been known to have antioxidant and anti-inflammatory effects. This study was designed to evaluate the effect of therapeutic hypothermia on paraquat intoxication.

Methods

Male Sprague-Dawley rats were given 50 mg/kg of paraquat intraperitoneally and divided into the normothermia (36-38 °C) group and the hypothermia (30-32 °C) group after 1 h of paraquat administration. The hypothermia group underwent 2 h of hypothermia followed by 2 h of rewarming. In the survival study, mortality was observed for 24 h after paraquat administration. An in the second experiment, lung tissues and plasma were harvested at 6 h after paraquat administration.

Results

The 12 h survival rate was significantly higher in the hypothermia group than in the normothermia group (100% vs. 50%, p < 0.05), but survival rates for 24 h were not different. Acute lung injury score was lower in the hypothermia group than in the normothermia group (p < 0.05). Thmalondialdehyde contents of lung tissues, plasma interleukin-6 and nitrite/nitrate concentrations were significantly decreased in the HT group compared to the NT group (p < 0.05).

Conclusion

Therapeutic hypothermia delayed early mortality and attenuated acute lung injury in paraquat intoxication.     

Serum matrix metalloproteinases in patients resuscitated from cardiac arrest. The association with therapeutic hypothermia

Aim

To study the systemic levels of matrix metalloproteinases (MMP) -7, -8 and -9 and their inhibitor TIMP-1 in cardiac arrest patients and the association with mild therapeutic hypothermia treatment on the serum concentration of these enzymes.

Methods

MMP-7, -8 and -9 and tissue inhibitor of metalloproteinases-1 (TIMP-1) were analysed in blood samples obtained from 51 patients resuscitated from cardiac arrest. The samples were taken at 24 and 48 h from restoration of spontaneous circulation (ROSC). The biomarker levels were compared between patients (N = 51) and healthy controls (N = 10) and between patients who did (N = 30) and patients who did not (N = 21) receive mild therapeutic hypothermia.

Results

MMP-7 (median 0.47 ng/ml), MMP-8 (median 31.16 ng/ml) and MMP-9 (median 253.00 ng/ml) levels were elevated and TIMP-1 levels suppressed (median 78.50 ng/ml) in cardiac arrest patients as compared with healthy controls at 24 h from ROSC. Hypothermia treatment associated with attenuated elevation of MMP-9 (p = 0.001) but not MMP-8 (p = 0.02) or MMP-7 (p = 0.69). Concentrations of MMPs -7, -8 and -9 correlated with the leukocyte count but not with C-reactive protein (CRP) or neurone-specific enolase (NSE) levels.

Conclusion

We demonstrated that the systemic levels of MMP-7, -8 and -9 but not TIMP-1 are elevated in cardiac arrest patients in the 48 h post-resuscitation period relative to the healthy controls. Patients who received therapeutic hypothermia had lower MMP-9 levels compared to non-hypothermia treated patients, which generates hypothesis about attenuation of inflammatory response by hypothermia treatment.     

Fluid therapy and acute kidney injury in cardiogenic shock after cardiac arrest

Aim of the study

It has recently been suggested that acute kidney injury (AKI) may strongly be influenced by post-resuscitation disease and cardiogenic shock (CS), and may not just be a consequence of cardiac arrest and time without spontaneous circulation. AKI also has been suggested as a strong independent predictor of in-hospital mortality. Therefore the present study aimed at investigating the effect of fluid management on the incidence of AKI in patients with cardiogenic shock after cardiac arrest treated by mild therapeutic hypothermia.

Methods

Fluid therapy and the incidence of acute kidney injury (AKI) was retrospectively reviewed in 51 patients with cardiogenic shock after cardiac arrest comparing patients with and without hemodynamic (PPV, SVV) and volumetric (ELWI, GEDI) monitoring.

Results

There was no significant difference in baseline or cardiac arrest characteristics between hemodynamic monitored patients and conventional monitored patients. 28 patients were monitored by standard monitoring, in 23 patients monitoring was complemented by a PICCO system. In the first 24 h of treatment the total amount of fluid was significantly higher in patients under PICCO monitoring compared to conventional monitoring (4375 ± 1285 ml vs. 5449 ± 1438 ml, p = 0.007). This was associated with a significant reduction in the incidence of AKI (RIFLE ‘I’/‘F’: PICCO-group: 1 (4.3%) vs. conventional group 8 (28.6%), p = 0.03).

Conclusion

The presented data suggest that volume therapy guided by volumetric (ELWI, GEDI) and arterial waveform derived variables (PPV, SVV) can reduce the incidence of AKI in patients with cardiogenic shock after cardiac arrest treated with mild therapeutic hypothermia.     

Clinical predictors of survival in patients treated with therapeutic hypothermia following cardiac arrest

Introduction

Therapeutic hypothermia has been shown to provide neuroprotection and improved survival in patients suffering a cardiac arrest. We report outcomes of consecutive patients receiving therapeutic hypothermia for cardiac arrest and describe predictors of short and long-term survival.

Methods

Eighty patients receiving therapeutic hypothermia between January 2005 and December 2008 were identified and categorized as those who survived and died. Outcomes and predictors of survival were determined.

Results

Forty-five patients (56%) survived to hospital discharge and were alive at 30 days and among survivors 41 (91%) were alive 1 year after discharge. Survivors were younger, were more likely to present with VF, required less epinephrine during resuscitation, were more likely to have preserved renal function, and were less likely to be taking beta-blockers and ACE inhibitors. Predictors of survival included VF on presentation (OR 14.9, CI 2.7-83.2, p = 0.002), pre-cardiac arrest aspirin use (OR 9.7, CI 1.6-61.1, p = 0.02), return of spontaneous circulation <20 min (OR 9.4, CI 2.2-41.1, p = 0.003), absence of coronary artery disease (OR 5.3, CI 1.1-24.7, p = 0.002) and preserved renal function.

Conclusion

Therapeutic hypothermia is useful in the treatment of patients suffering a cardiac arrest. Several clinical factors may aid in predicting patients who are likely to survive after a cardiac arrest.     

The Chinese Behavior Pain Scale for critically ill patients: Translation and psychometric testing

Background

Common pain assessment tools might not be the suitable tools to measure ventilated, critically ill patients’ pain. The Behavioral Pain Scale measures observable behavior indicative of pain experienced by mechanically ventilated patients.

Objective

This study was conducted to generate a Chinese-language version of the Behavioral Pain Scale and to test its psychometric properties.

Design

This study was a prospective psychometric study.

Settings/participants

: Seventy patients were recruited from two intensive care units in a medical center.

Methods

After instrument translation, psychometric testing which included inter-rater reliability, test-retest reliability, and construct validity was conducted. The construct validity was tested using criterion and discriminant validation strategies. A receiver-operating characteristic curve analysis was conducted to evaluate the ability of the translated tool to correctly detect pain. Measurement of body temperature and endotracheal suctioning were, respectively, selected as the non-painful and painful procedures. Two research nurses observed patients’ pain-related behaviors when they were at rest and before/during the non-painful/painful procedures.

Results

The Chinese translation captured the content of the original tool with appropriate adaptation to the cultural context. The inter-rater and test-retest reliabilities were confirmed by good Pearson correlations (r = .50-1.00, p < .001) and high agreement percentages (72.9-100.0%). The criterion validity was confirmed by (a) the score during the painful procedure for patients who considered it to be painful being higher than the score for patients who considered it not to be painful (t = 2.28, p = .03), and (b) an increase in the score occurred for two (2.9%) patients during the non-painful procedure and for 68 (97.1%) patients during the painful procedure. The discriminant validity was confirmed by post hoc comparisons in a one-way ANOVA: the scores during the painful procedure were higher than the scores on other occasions (F = 377.7, p < .001). The receiver-operating characteristic curve analysis showed that the translated tool had moderate accuracy.

Conclusions

The Chinese-language version of the Behavior Pain Scale was shown to be reliable and valid for adult patients on mechanical ventilation in medical intensive care units when exposed to rest, a non-painful procedure, and a painful procedure. An assessment tool including pain-related observable indicators can be used as one source to assess a patient's pain, especially with ventilated or non-communicative patients.     

Association between a quantitative CT scan measure of brain edema and outcome after cardiac arrest

Background

Cerebral edema is one physical change associated with brain injury and decreased survival after cardiac arrest. Edema appears on computed tomography (CT) scan of the brain as decreased X-ray attenuation by gray matter. This study tested whether the gray matter attenuation to white matter attenuation ratio (GWR) was associated with survival and functional recovery.

Methods

Subjects were patients hospitalized after cardiac arrest at a single institution between 1/1/2005 and 7/30/2010. Subjects were included if they had non-traumatic cardiac arrest and a non-contrast CT scan within 24 h after cardiac arrest. Attenuation (Hounsfield Units) was measured in gray matter (caudate nucleus, putamen, thalamus, and cortex) and in white matter (internal capsule, corpus callosum and centrum semiovale). The GWR was calculated for basal ganglia and cerebrum. Outcomes included survival and functional status at hospital discharge.

Results

For 680 patients, 258 CT scans were available, but 18 were excluded because of hemorrhage (10), intravenous contrast (3) or technical artifact (5), leaving 240 CT scans for analysis. Lower GWR values were associated with lower initial Glasgow Coma Scale motor score. Overall survival was 36%, but decreased with decreasing GWR. The average of basal ganglia and cerebrum GWR provided the best discrimination. Only 2/58 subjects with average GWR < 1.20 survived and both were treated with hypothermia. The association of GWR with functional outcome was completely explained by mortality when GWR < 1.20.

Conclusions

Subjects with severe cerebral edema, defined by GWR < 1.20, have very low survival with conventional care, including hypothermia. GWR estimates pre-treatment likelihood of survival after cardiac arrest.     

Hypokalemia during the cooling phase of therapeutic hypothermia and its impact on arrhythmogenesis

Background

Mild to moderate therapeutic hypothermia (TH) has been shown to improve survival and neurological outcome in patients resuscitated from out-of-hospital cardiac arrest (OHCA) with ventricular fibrillation (VF) as the presenting rhythm. This approach entails the management of physiological variables which fall outside the realm of conventional critical cardiac care. Management of serum potassium fluxes remains pivotal in the avoidance of lethal ventricular arrhythmia.

Methods

We retrospectively analyzed potassium variability with TH and performed correlative analysis of QT intervals and the incidence of ventricular arrhythmia.

Results

We enrolled 94 sequential patients with OHCA, and serum potassium was followed intensively. The average initial potassium value was 3.9 ± 0.7 mmol l⁻¹ and decreased to a nadir of 3.2 ± 0.7 mmol l⁻¹ at 10 h after initiation of cooling (p < 0.001). Eleven patients developed sustained polymorphic ventricular tachycardia (PVT) with eight of these occurring during the cooling phase. The corrected QT interval prolonged in relation to the development of hypothermia (p < 0.001). Hypokalemia was significantly associated with the development of PVT (p = 0.002), with this arrhythmia being most likely to develop in patients with serum potassium values of less than 2.5 mmol l⁻¹ (p = 0.002). Rebound hyperkalemia did not reach concerning levels (maximum 4.26 ± 0.8 mmol l⁻¹ at 40 h) and was not associated with the occurrence of ventricular arrhythmia. Furthermore, repletion of serum potassium did not correlate with the development of ventricular arrhythmia.

Conclusions

Therapeutic hypothermia is associated with a significant decline in serum potassium during cooling. Hypothermic core temperatures do not appear to protect against ventricular arrhythmia in the context of severe hypokalemia and cautious supplementation to maintain potassium at 3.0 mmol l⁻¹ appears to be both safe and effective.     

Feasibility and safety of combined percutaneous coronary intervention and therapeutic hypothermia following cardiac arrest

Review

Mild therapeautic hypothermia (MTH) has been associated with cardiac dysrhythmias, coagulopathy and infection. After restoration of spontaneous circulation (ROSC), many cardiac arrest patients undergo percutaneous coronary intervention (PCI). The safety and feasibility of combined MTH and PCI remains unclear. This is the first study to evaluate whether PCI increases cardiac risk or compromises functional outcomes in comatose cardiac arrest patients who undergo MTH.

Methods

Ninety patients within a 6-h window following cardiac arrest and ROSC were included. Twenty subjects (23%) who underwent PCI following MTH induction were compared to 70 control patients who underwent MTH without PCI. The primary endpoint was the rate of dysrhythmias; secondary endpoints were time-to-MTH induction, rates of adverse events (dysrhythmia, coagulopathy, hypotension and infection) and mortality.

Results

Patients who underwent PCI plus MTH suffered no statistical increase in adverse events (P = .054). No significant difference was found in the rates of dysrhythmias (P = .27), infection (P = .90), coagulopathy (P = .90) or hypotension (P = .08). The PCI plus MTH group achieved similar neurological outcomes (modified Rankin Scale (mRS) ≤3 (P = .42) and survival rates (P = .40). PCI did not affect the speed of MTH induction; the target temperature was reached in both groups without a significant time difference (P = .29).

Conclusion

Percutaneous coronary intervention seems to be feasible when combined with MTH, and is not associated with increased cardiac or neurological risk.     

Perfluorocarbon induced intra-arrest hypothermia does not improve survival in a swine model of asphyxial cardiac arrest

Background

Pulseless electrical activity is an important cause of cardiac arrest. Our purpose was to determine if induction of hypothermia with a cold perfluorocarbon-based total liquid ventilation (TLV) system would improve resuscitation success in a swine model of asphyxial cardiac arrest/PEA.

Methods

Twenty swine were randomly assigned to control (C, no ventilation, n = 11) or TLV with pre-cooled PFC (n = 9) groups. Asphyxia was induced by insertion of a stopper into the endotracheal tube, and continued in both groups until loss of aortic pulsations (LOAP) was reached, defined as a pulse pressure less than 2 mmHg. The TLV animals underwent asphyxial arrest for an additional 2 min after LOAP, followed by 3 min of hypothermia, prior to starting CPR. The C animals underwent 5 min of asphyxia beyond LOAP. Both groups then underwent CPR for at least 10 min. The endpoint was the resumption of spontaneous circulation maintained for 10 min.

Results

Seven of 9 animals achieved resumption of spontaneous circulation (ROSC) in the TLV group vs. 5 of 11 in the C group (p = 0.2). The mean pulmonary arterial temperature was lower in total liquid ventilation animals starting 4 min after induction of hypothermia (TLV 36.3 ± 0.2 °C vs. C 38.1 ± 0.2 °C, p < 0.0001). Arterial pO₂ was higher in total liquid ventilation animals at 2.5 min of CPR (TLV 76 ± 12 mmHg vs. C 44 ± 2 mmHg; p = 0.03).

Conclusion

Induction of moderate hypothermia using perfluorocarbon-based total liquid ventilation did not improve ROSC success in this model of asphyxial cardiac arrest.     

Association between transient acute kidney injury and morbidity and mortality after lung transplantation: A retrospective cohort study

Purpose

Acute kidney injury (AKI) is a common occurrence after lung transplantation (LTx). Whether transient AKI or early recovery is associated with improved outcome is uncertain. Our aim was to describe the incidence, factors, and outcomes associated with transient AKI after LTx.

Materials and Methods

We performed a retrospective cohort study of all adult recipients of LTx at the University of Alberta between 1990 and 2011. Our primary outcome transient AKI was defined as return of serum creatinine below Kidney Disease–Improving Global Outcome AKI stage I within 7 days after LTx. Secondary outcomes included occurrence of postoperative complications, mortality, and long-term kidney function.

Results

Of 445 LTx patients enrolled, AKI occurred in 306 (68.8%) within the first week after LTx. Of these, transient AKI (or early recovery) occurred in 157 (51.3%). Transient AKI was associated with fewer complications including tracheostomy (17.2% vs 38.3%; P < .001), reintubation (16.4% vs 41.9%; P < .001), decreased duration of mechanical ventilation (median [interquartile range], 69 [41-142] vs 189 [63-403] hours; P < .001), and lower rates of chronic kidney disease at 3 months (28.5% vs 51.1%, P < .001) and 1 year (49.6% vs 66.7%, P = .01) compared with persistent AKI. Factors independently associated with persistent AKI were higher body mass index (per unit; odds ratio [OR], 0.91; 95% confidence interval, 0.85-0.98; P = .01), cyclosporine use (OR, 0.29; 0.12-0.67; P = .01), longer duration of mechanical ventilation (per hour [log transformed]; OR, 0.42; 0.21-0.81; P = .01), and AKI stages II to III (OR, 0.16; 0.08-0.29; P < .001). Persistent AKI was associated with higher adjusted hazard of death (hazard ratio, 1.77 [1.08-2.93]; P = .02) when compared with transient AKI (1.44 [0.93-2.19], P = .09) and no AKI (reference category), respectively.

Conclusions

Transient AKI after LTx is associated with fewer complications and improved survival. Among survivors, persistent AKI portends an increased risk for long-term chronic kidney disease.     

Severe QTc prolongation under mild hypothermia treatment and incidence of arrhythmias after cardiac arrest--a prospective study in 34 survivors with continuous Holter ECG

Background

Mild hypothermia treatment (32-34 °C) in survivors after cardiac arrest (CA) is clearly recommended by the current guidelines. The effects of cooling procedure towards QT interval have not been evaluated so far outside of case series. In a prospective study 34 consecutive survivors after cardiac arrest were continuously monitored with Holter ECG over the first 48 h.

Patients and methods

A total of 34 patients were analysed and received mild therapeutic hypothermia treatment (MTH) according to the current guidelines and irrespective of the initial rhythm. At admission to hospital and in the field in case of OHCA, a 12-lead ECG was performed in all patients.

Results

During cooling the incidence of ventricular tachycardia was low (8.8%) and in none of the patients Torsade de pointes occurred. The QTc interval was within normal range at first patient contact with EMS in the field (440.00 ms; IQR 424.25-476.75; n = 17) but during hypothermia treatment the QTc interval was significantly prolonged at 33 °C after 24 h of cooling (564.47 ms; IQR 512.41-590.00; p = 0.0001; n = 34) and decreased after end of hypothermia to baseline levels (476.74 ms; 448.71-494.97; p = 0.15).

Conclusion

The QTc interval was found to be significantly prolonged during MTH treatment, and some severe prolongations >670 ms were observed, without a higher incidence of life-threatening arrhythmias, especially no Torsade des pointes were detected. However, routine and frequent ECG recording with respect to the QTc interval should become part of any hypothermia standard operation protocol and should be recommended by official guidelines.     

Antiplatelet effect of clopidogrel is reduced in patients treated with therapeutic hypothermia after cardiac arrest

Background

The platelet inhibitor clopidogrel is administered to patients treated with therapeutic hypothermia following cardiac arrest due to acute coronary syndromes. Interactions with proton pump inhibitors and genetics are factors with a known potential to attenuate the platelet inhibition of clopidogrel. In patients treated with therapeutic hypothermia, reduced gastrointestinal function and hypothermia may also reduce the effect of clopidogrel. To investigate the net platelet inhibition of clopidogrel, we have measured the platelet reactivity index in patients treated with therapeutic hypothermia.

Methods and results

Twenty-five Caucasian patients treated with clopidogrel and therapeutic hypothermia were prospectively included. Therapeutic hypothermia was defined as 33-34 °C and delivered for 24 h. Clopidogrel loading doses (300-600 mg) were administered enterally the day of admission and followed by 75 mg daily. Blood samples were collected on day 1 (n = 25) and day 3 (n = 16). The samples were analysed for inhibition by clopidogrel with a vasodilator stimulated phosphoprotein phosphorylation kit. On day 1 and day 3, platelet reactivity index was 0.77 ± 0.09 and 0.57 ± 0.16, respectively. The number of patients with a satisfactory antiplatelet effect (defined as platelet reactivity index <0.5) were 0 (0%) and 5 (31%), respectively.

Conclusion

In patients treated with therapeutic hypothermia after cardiac arrest, the effect of clopidogrel on platelets was virtually nonexistent on day 1 after administration, with some improvement on day 3.     

Extra corporeal life support makes advanced radiologic examinations and cardiac interventions possible in patients with cardiac arrest

Objectives

Extra corporeal life support (ECLS) with a mobile system is an option in the treatment of cardiac arrest often of unknown reason. After commencing ECLS the search for a provoking origin may include advanced radiologic examinations before deciding further treatment.

Methods

Fifty-eight patients with circulatory arrest were treated with ECLS. In 15 cases the patient went through CT scans of the cerebrum, thorax and abdomen, pulmonary angiography, and or invasive cardiologic examinations. Two patients were transported in ambulance and helicopter on ECLS before the examinations.

Results

The underlying diagnosis in the 15 patients were: lung embolism (n = 6), accidental hypothermia (n = 2), myocardial infarction (n = 2), WPW syndrome (n = 1), sepsis (n = 1), disseminated intravascular coagulation (n = 2), high voltage accident (n = 1). Only in the last mentioned patient the CT scan was indicative of major brain damage, and further treatment was stopped. Five of the 15 examined patients survived. The diagnoses in the survivors were lung embolism (n = 2), myocardial infarction (n = 1), WPW syndrome (n = 1), and accidental hypothermia (n = 1). The results of the radiologic examinations had great influence on all treatments.

Conclusions

It is possible to make radiological examinations i.e., CT scans, pulmonary and coronary angiography in patients suffering heart arrest of unknown origin with the use of ECLS in order to improve patient treatment in this very high-risk population.     

The infusion of opioids during terminal withdrawal of mechanical ventilation in the medical intensive care unit

Context

Most deaths in intensive care units occur after limitation or withdrawal of life-sustaining therapies. Often these patients require opioids to assuage suffering; yet, little has been documented concerning their use in the medical intensive care unit.

Objectives

To determine the dose and factors influencing the use of opioids in patients undergoing terminal withdrawal of mechanical ventilation in this setting.

Methods

Data were prospectively collected from 74 consecutive patients expected to die soon after extubation. The doses of morphine, effect on time to death, and relation of dose to diagnostic categories were analyzed.

Results

The mean (±standard deviation) dose of morphine given to patients during the last hour of mechanical ventilation was 5.3 mg/hour. Patients dying after extubation received 10.6 mg/hour just before death. Immediately before extubation, the dose correlated directly with chronic medical opioid use and sepsis with respiratory failure and inversely with coma after cardiopulmonary resuscitation or a primary neurological event. After terminal extubation, the final morphine dose correlated directly with the presence of sepsis with respiratory failure and chronic pulmonary disease. The mean time to death after terminal extubation was 152.7 ± 229.5 minutes without correlation with premorbid diagnoses. After extubation, each 1 mg/hour increment of morphine infused during the last hour of life was associated with a delay of death by 7.9 minutes (P = 0.011).

Conclusion

Premorbid conditions may influence the dose of morphine given to patients undergoing terminal withdrawal of mechanical ventilation. Higher doses of morphine are associated with a longer time to death.     

Do smokers with chronic obstructive pulmonary disease report their smoking status reliably? A comparison of self-report and bio-chemical validation

Background

Chronic obstructive pulmonary disease (COPD) is predominantly caused by cigarette smoking and is considered a worldwide preventable chronic illness. Smoking cessation is considered the primary intervention for disease management and nurses should play a major role in assisting patients to stop smoking. Currently there is a lack of professional consensus on how cessation interventions should be evaluated. The vast array of biochemical markers reported in the literature can be confusing and can make the comparisons of results difficult.

Objective

To validate self-report data on smoking with exhaled carbon monoxide in patients with chronic obstructive pulmonary disease over twelve months.

Design

We performed a secondary analysis of a previously published randomized controlled trial evaluating nursing interventions to assist respiratory patients to stop smoking.

Setting

Northern Ireland's Regional Respiratory Centre.

Participants

A total of 91 cigarette smokers attending secondary care for the treatment for COPD participated in the study.

Method

Self-reported smoking status and cigarettes smoked per day were compared to exhaled carbon monoxide readings at baseline, 2, 3, 6, 9 and 12 months. The cut-off value of ≤10 ppm was used to identify non-smokers. The p-values are based on Pearson's correlation coefficient and Kappa Coefficient as appropriate.

Results

Findings suggest self-reported smoking status and cigarette consumption amongst patients with chronic obstructive pulmonary disease was highly consistent with exhaled carbon monoxide results (p = 0.001-0.003).

Conclusion

The majority of patients with chronic obstructive pulmonary disease reliably report their cigarette consumption.     

Therapeutic hypothermia is associated with improved neurologic outcome and survival in cardiac arrest survivors of non-shockable rhythms

Background

Therapeutic hypothermia improves neurologic outcomes in patients resuscitated from cardiac arrest due to ventricular fibrillation. However, its role in patients with cardiac arrest due to non-shockable rhythms (pulseless electrical activity (PEA) and asystole) is unclear. We hypothesized that therapeutic hypothermia favorably impacts neurologic outcome and survival in patients resuscitated from cardiac arrest due to non-shockable rhythms.

Methods

Retrospectively collected data on consecutive adult patients admitted to Hartford Hospital from 1/1/2004 to 11/1/2010 who survived a cardiac arrest due to PEA or asystole were analyzed. Patients who underwent therapeutic hypothermia (1/1/2007-11/1/2010) formed the hypothermia group while patients admitted prior to the institution of therapeutic hypothermia (1/1/2004-1/1/2007) at Hartford Hospital formed the control group. The primary end-point was measured using the Pittsburgh cerebral performance category (CPC) scale and patients were assessed for a good (CPC 1 and 2) or poor (CPC 3-5) neurological outcome prior to discharge from hospital. A secondary end-point was measured as survival at discharge from hospital.

Results

Of 100 post-cardiac arrest patients included in the study, 15/52 (29%) patients in the hypothermia group had a good neurologic outcome as compared to 5/43 (10%) patients in the control group (P = 0.021). On multivariate analysis, the odds ratio for good neurologic outcome and survival at discharge from the hospital with therapeutic hypothermia as compared to control were 4.35 (95% CI 1.10-17.24, P = 0.04) and 5.65 (CI 1.66-19.23, P = 0.006) respectively.

Conclusion

Therapeutic hypothermia is associated with favorable neurologic outcome and survival in patients resuscitated after cardiac arrest due to non-shockable rhythms.