Arterial minus end-tidal CO2 as a prognostic factor of hospital survival in patients resuscitated from cardiac arrest

AIMS: The purpose of this study was to determine the clinical value of arterial minus end-tidal CO(2) [P(a-et)CO(2)] and alveolar dead space ventilation ratio (V(dA)/V(t)) as indicators of hospital mortality in patients that have been resuscitated from cardiac arrest at emergency department. MATERIALS AND METHODS: Forty-four patients with a return of spontaneous circulation (ROSC) after cardiac arrest were studied in the emergency department of a university teaching hospital from March 2004 to February 2006. Mean arterial pressure (MAP), serum lactate, arterial blood gas studies, end-tidal CO(2) (EtCO(2)), P(a-et)CO(2), and V(dA)/V(t) were evaluated at 1 h after ROSC. We compared these variables between hospital survivors and non-survivors. RESULTS: The rates of ventricular fibrillation and pulseless ventricular tachycardia in hospital survivors were higher than those of non-survivors (53.0 and 9.7%, respectively, p=0.002). Hospital survivors had significantly higher MAP, lower serum lactate, lower P(a-et)CO(2), and lower V(dA)/V(t) value than non-survivors. Receiver operator characteristic (ROC) curves of serum lactate, P(a-et)CO(2), and V(dA)/V(t) showed significant sensitivity and specificity for hospital mortality. Specifically, lactate > or = 10.0 mmol/L, P(a-et)CO(2) > or = 12.5 mmHg, and V(dA)/V(t) > or = 0.348 were all associated with high hospital mortality (p=0.000, 0.001 and 0.000, respectively). CONCLUSIONS: This study showed that high serum lactate, high P(a-et)CO(2) and high V(dA)/V(t) during early ROSC in cardiac arrest patients suggest high hospital mortality. If future studies validate this model, the P(a-et)CO(2) and V(dA)/V(t) may provide useful guidelines for the early post-resuscitation care of cardiac arrest patients in emergency departments.     

A phased approach to cardiac arrest resuscitation involving ventricular fibrillation and pulseless ventricular tachycardia

With the release of the 2010 American Heart Association (AHA) Guidelines for cardiopulmonary resuscitation and emergency cardiac care, evidence regarding management of out-of-hospital cardiac arrest suggests a more fundamental approach. To aid in understanding and learning, this article proposes a method that optimizes the timing and delivery of evidence-proven therapies with a 3-phase approach for out-of-hospital resuscitation from ventricular fibrillation and pulseless ventricular tachycardia. Although this model is not a new concept, it is largely based on the 2010 AHA Guidelines, enhancing the philosophy of the "CAB" concept (Chest compressions/Airway management/Breathing rescue).     

The dynamic pattern of end-tidal carbon dioxide during cardiopulmonary resuscitation: difference between asphyxial cardiac arrest and ventricular fibrillation/pulseless ventricular tachycardia cardiac arrest

Introduction  

Partial pressure of end-tidal carbon dioxide (PetCO2) during cardiopulmonary resuscitation (CPR) correlates with cardiac output and consequently has a prognostic value in CPR. In our previous study we confirmed that initial PetCO2 value was significantly higher in asphyxial arrest than in ventricular fibrillation/pulseless ventricular tachycardia (VF/VT) cardiac arrest. In this study we sought to evaluate the pattern of PetCO2 changes in cardiac arrest caused by VF/VT and asphyxial cardiac arrest in patients who were resuscitated according to new 2005 guidelines.     

Survival rate and factors associated with 1-month survival of witnessed out-of-hospital cardiac arrest of cardiac origin with ventricular fibrillation and pulseless ventricular tachycardia: the Utstein Osaka project

OBJECTIVE: We reassessed 1-month survival of patients with witnessed out-of-hospital cardiac arrest (OHCA) of cardiac origin with ventricular fibrillation (VF) or pulseless ventricular tachycardia (VT) in Osaka, Japan, and identified factors associated with 1-month survival using updated data from 1998 to 2004 collected based on the Utstein Style. METHODS: Using the Utstein Osaka Project database, we analyzed 1028 cases which met the following criteria: (1) patient age 18 years or older; (2) presumed cardiac origin based on the definition of the Utstein Style; (3) witnessed by citizens; (4) VF or pulseless VT at the time of arrival of the ambulance. The main outcome measure was survival at 1 month after collapse. Variables to develop a predictive model for 1-month survival were selected by stepwise logistic regression. RESULTS: Survival at 1 month was 19.6%. Factors retained in the final logistic regression were age, sex, type of witness, and time interval from (a) ambulance call receipt to cardiopulmonary resuscitation (CPR) by the ambulance crew; (b) ambulance call to defibrillation; (c) CPR by the ambulance crew to hospital arrival. Area under the receiver-operating characteristic curve for the model developed with the six variables was 0.738 and Hosmer-Lemshow goodness-of-fit p-value was 0.94. CONCLUSION: We successfully developed a model to estimate the probability of 1-month survival using variables easy to collect in the early phase of resuscitation, and this model would help physicians and family members predict the likelihood of 1-month survival of OHCA patients on admission.     

On-line expiratory CO2 monitoring

Summary The single breath test for carbon dioxide (SBT-CO₂) is the plot of expired FCO₂ or CO₂% against expired volume. It can be monitored during anaesthesia and in the intensive care unit with modest additions to generally available equipment. This paper describes some aspects of a computer program for presenting SBT-CO₂ during controlled ventilation, in particular, the corrections to the primary data necessary for scientific accuracy. Examples are given of how the use of SBT-CO₂ has increased our understanding of factors which influence the arterial-endtidal PCO₂ difference (PaCO₂-P_E, CO₂). PaCO₂-P_E, CO₂ is, in a given individual, usually dependent on tidal volume and frequency. Changes in lung volume and manoeuvres such as opening the pleura also affect gas exchange. Monitoring CO₂ elimination gives a measure of metabolic rate if ventilation and pulmonary perfusion are maintained. This facilitates ventilatory therapy in situations where CO₂ production is greatly increased, e.g. sepsis and tetanus. On the other hand, if metabolism and ventilation are unchanged, a reduction in CO₂ elimination implies reduced pulmonary perfusion. This can be seen during increased right-left shunting, such as in surgery in patients with congenital heart disease.     

Use of beta-blockers for the treatment of cardiac arrest due to ventricular fibrillation/pulseless ventricular tachycardia: a systematic review

Introduction

Advanced Life Support guidelines recommend the use of epinephrine during Cardiopulmonary Resuscitation (CPR), as to increase coronary blood flow and perfusion pressure through its alpha-adrenergic peripheral vasoconstriction, allowing minimal rises in coronary perfusion pressure to make defibrillation possible. Contrasting to these alpha-adrenergic effects, epinephrine's beta-stimulation may have deleterious effects through an increase in myocardial oxygen consumption and a reduction of subendocardial perfusion, leading to postresuscitation cardiac dysfunction.

Objective

The present paper consists of a systematic review of the literature regarding the use of beta-blockade in cardiac arrest due to ventricular fibrillation (VF) and pulseless ventricular tachycardia (VT).

Methods

Studies were identified through MEDLINE electronic databases research and were included those regarding the use of beta-blockade during CPR.

Results

Beta-blockade has been extensively studied in animal models of CPR. These studies not only suggest that beta-blockade could reduce myocardial oxygen requirements and the number of shocks necessary for defibrillation, but also improve postresuscitation myocardial function, diminish arrhythmia recurrences and prolong survival. A few case reports described successful beta-blockade use in patients, along with two prospective human studies, suggesting that it could be safe and effectively used during cardiac arrest in humans.

Conclusion

Even though the existing literature points toward a beneficial effect of beta-blockade in patients presenting with cardiac arrest due to VF/pulseless VT, high quality human trials are still lacking to answer this question definitely.     

Relationship between respiration, end-tidal CO2, and BOLD signals in resting-state fMRI

A significant component of BOLD fMRI physiological noise is caused by variations in the depth and rate of respiration. It has previously been demonstrated that a breath-to-breath metric of respiratory variation (respiratory volume per time; RVT), computed from pneumatic belt measurements of chest expansion, has a strong linear relationship with resting-state BOLD signals across the brain. RVT is believed to capture breathing-induced changes in arterial CO₂, which is a cerebral vasodilator; indeed, separate studies have found that spontaneous fluctuations in end-tidal CO₂ (PETCO₂) are correlated with BOLD signal time series. The present study quantifies the degree to which RVT and PETCO₂ measurements relate to one another and explain common aspects of the resting-state BOLD signal. It is found that RVT (particularly when convolved with a particular impulse response, the “respiration response function”) is highly correlated with PETCO₂, and that both explain remarkably similar spatial and temporal BOLD signal variance across the brain. In addition, end-tidal O₂ is shown to be largely redundant with PETCO₂. Finally, the latency at which PETCO₂ and respiration belt measures are correlated with the time series of individual voxels is found to vary across the brain and may reveal properties of intrinsic vascular response delays.     

Correlations between hemodynamic, oxygenation and tissue perfusion parameters during asphyxial cardiac arrest and resuscitation in a pediatric animal model

Aim

To analyze the correlations between hemodynamic, oxygenation and tissue perfusion values in an infant animal model of asphyctic cardiac arrest (ACA).

Methods

A prospective observational animal study was performed in seventy one, two month-old piglets. CA was induced by removal of mechanical ventilation and was followed by advanced life support after at least 10 min. Correlations between hemodynamic [heart rate (HR), mean arterial pressure (MAP), cardiac index (CI), stroke volume index (SVI) and intrathoracic blood index (ITBI) measured by PiCCO method], blood gas values (arterial and central venous saturation), and tissue perfusion values [intramucosal gastric pH (pHi), and tissue oxygenation (cerebral and renal saturation)] were analyzed during asphyxia, resuscitation and after return of spontaneous circulation (ROSC).

Results

Among global hemodynamic parameters, the only moderate significant correlation observed was between CI and ITBI (r = .551). Among tissue oxygenation/perfusion values, a moderate to good significant correlation (r = .460-.763) between arterial oxygen saturation, central venous, renal and cerebral oxygen saturation was observed. Lactic acid, potassium (K) and pHi were correlated (r = .561-.639), but no correlation was found between them and tissue oxygenation parameters. Global hemodynamic parameters (CI, HR, MAP) did not correlate with renal and cerebral saturations and tissue perfusion parameters.

Conclusions

During ACA and after ROSC global hemodynamic parameters do not correlate with oxygenation and tissue perfusion values. Additional studies which assess the potential usefulness of tissue oxygenation/perfusion parameters during cardiac arrest and ROSC are needed.     

The incidence and significance of bacteremia in out of hospital cardiac arrest

Background

The most common etiology of cardiac arrest is presumed of myocardial origin. Recent retrospective studies indicate that preexisting pneumonia, a form of sepsis, is frequent in patients who decompensate with abrupt cardiac arrest without preceding signs of septic shock, respiratory failure or severe metabolic disorders shortly after hospitalization. The contribution of pre-existing infection on pre and post cardiac arrest events remains unknown and has not been studied in a prospective fashion. We sought to examine the incidence of pre-existing infection in out-of hospital cardiac arrest (OHCA) and assess characteristics associated with bacteremia, the goal standard for presence of infection.

Methods and results

We prospectively observed 250 OHCA adult patients who presented to the Emergency Department (ED) between 2007 and 2009 to an urban academic teaching institution. Bacteremia was defined as one positive blood culture with non-skin flora bacteria or two positive blood cultures with skin flora bacteria. 77 met pre-defined exclusion criteria. Of the 173 OHCA adults, 65 (38%) were found to be bacteremic with asystole and PEA as the most common presenting rhythms. Mortality in the ED was significantly higher in bacteremic OHCA (75.4%) compared to non-bacteremic OHCA (60.2%, p < 0.05). After adjustment for potential confounders, predictive factors associated with bacteremic OHCA were lower initial arterial pH, higher lactate, WBC, BUN and creatinine.

Conclusions

Over one-third of OHCA adults were bacteremic upon presentation. These patients have greater hemodynamic instability and significantly increased short-term mortality. Further studies are warranted to address the epidemiology of infection as possible cause of cardiac arrest.     

院前心脏停搏与院内心脏停搏复苏存活率的比较

目的：分析我院急诊中心心脏停搏患者心肺复苏（CPR）存活率及其影响因素,并比较院前发生心脏停搏与院内发生心脏停搏复苏存活率。方法：对我院急诊中心78例心搏骤停（cardiacarrest,CA）患者的资料进行回顾性分析,比较院前发生心搏骤停组和院内发生心搏骤停组的CPR开始时间（从心脏停搏至CPR开始时间）、气管插管时间、CPR持续时间、开始除颤时间、除颤次数、肾上腺素用量及存活率。结果：院前组复苏存活率2．86％,院内组复苏存活率11．62％。两组CPR开始时间、气管插管时间、存活率比较差异有统计学意义（P〈0．01）,CPR持续时间、除颤次数及肾上腺素用量比较差异无统计学意义。结论：院前心脏停搏较院内心脏停搏复苏存活率低,与“生命链”未彻底落实及急救水平低有关。普及全民急救知识,加强完善急救医疗体系建设,早期除颤及早期亚低温治疗,是提高CPR成功率及复苏存活率的重要措施。     

Non-invasive pulmonary blood flow measurement by means of CO2 analysis of expiratory gases

Two different methods of CO₂-derived non-invasive assessment of the pulmonary blood flow were evaluated. The principle of the formula, as proposed by Gedeon et al., is based on a rapid change in arterial CO₂ content and subsequent changes in endtidal PCO₂ and CO₂ elimination. Both methods were compared to thermodilution cardiac output in 44 postoperative patients after CABG. The first method consisted of a short period of hyperventilation followed by hypoventilation. Comparison with the thermodilution cardiac output showed a low correlation coefficient: using a measured arterial —end-tidal PCO₂ difference (E)r=0.397 was found. Entering a fixed E of 0.53 kPa resulted inr=0.454. These disappointing figures may be explained by procedural mistakes. The second method, based on partial rebreathing by means of adding an additional dead space of 220 ml for 30–45 s, correlated very well with the thermodilution findings. Correlation coefficients ofr=0.925 (measured E) andr=0.925 (fixed E) were found. Considering the simplicity of the method, the additional dead space approach seems to be an easy and reliable way to determine pulmonary blood flow.     

Low-flow CO2 removal integrated into a renal-replacement circuit can reduce acidosis and decrease vasopressor requirements

Introduction

Lung-protective ventilation in patients with ARDS and multiorgan failure, including renal failure, is often paralleled with a combined respiratory and metabolic acidosis. We assessed the effectiveness of a hollow-fiber gas exchanger integrated into a conventional renal-replacement circuit on CO₂ removal, acidosis, and hemodynamics.

Methods

In ten ventilated critically ill patients with ARDS and AKI undergoing renal- and respiratory-replacement therapy, effects of low-flow CO₂ removal on respiratory acidosis compensation were tested by using a hollow-fiber gas exchanger added to the renal-replacement circuit. This was an observational study on safety, CO₂-removal capacity, effects on pH, ventilator settings, and hemodynamics.

Results

CO₂ elimination in the low-flow circuit was safe and was well tolerated by all patients. After 4 hours of treatment, a mean reduction of 17.3 mm Hg (−28.1%) pCO₂ was observed, in line with an increase in pH. In hemodynamically instable patients, low-flow CO₂ elimination was paralleled by hemodynamic improvement, with an average reduction of vasopressors of 65% in five of six catecholamine-dependent patients during the first 24 hours.

Conclusions

Because no further catheters are needed, besides those for renal replacement, the implementation of a hollow-fiber gas exchanger in a renal circuit could be an attractive therapeutic tool with only a little additional trauma for patients with mild to moderate ARDS undergoing invasive ventilation with concomitant respiratory acidosis, as long as no severe oxygenation defects indicate ECMO therapy.     

Measurement of pulmonary CO2 elimination must exclude inspired CO2 measured at the capnometer sampling site

Objective. The pulmonary elimination of the volume of CO₂ per breath (VCO₂/br, integration of product of airway flow ( ) and PCO₂ over a single breath) is a sensitive monitor of cardio-pulmonary function and tissue metabolism. Negligible inspired PCO₂ results when the capnometry sampling site (SS) is positioned at the entry of the inspiratory limb to the airway circuit. In this study, we test the hypothesis that moving SS lungward will result in significant inspired CO₂ (VCO₂[I]), that needs to be excluded from VCO₂/br.Methods. We ventilated a mechanical lung simulator with tidal volume (V_T) of 800 mL at 10 breaths/min. CO₂ production, generated by burning butane in a separate chamber, was delivered to the lung. Airway and PCO₂ were measured (Capnomac Ultima, Datex), digitized (100 Hz for 60 s), and stored by microcomputer. Then, computer algorithms corrected for phase diferences between and PCO₂ and calculated expired and inspired VCO₂ (VCO₂[E] and VCO₂[I]) for each breath, whose difference equalled overall VCO₂/br. The lung and Y-adapter (where the inspiratory and expiratory limbs of the circuit joined) were connected by the SS and a connecting tube in varying order.Results. During ventilation of the lung model (V_T = 800 ml) with SS adjacent to the inspiratory limb, VCO₂[E] was 16.8± 0.4 ml and VCO₂[I] was 1.1 ±0.1 ml, resulting in overall VCO₂/br (VCO₂[E] —VCO₂[I]) of 15.7 ± 0.4 ml. If VCO₂[I] was ignored in the determination of VCO₂/br, then the %error that VCO₂[E] overestimated VCO₂/br was 7.2± 0.3%. This %error significantly increased (p < 0.05, Student's t-test) when V_T was decreased to 500 mL (%error = 12.4 ± 0.8%) or when SS was moved to the lungward side of a 60 mL connecting tube (VCO₂[I] = 2.8 ± 0.2, %error = 18.2 ± 1.6) or a 140 mL tube (VCO₂[I] = 5.9±03 mL, %error = 37.5±3.3).Conclusions. When the SS was moved lungward from the inspiratory limb, instrumental dead space (VD _INSTR) increased and, at end-expiration, contained exhaled CO₂ from the previous breath. During the next inspiration, this CO₂ was rebreathed relative to SS (i.e. VCO₂[I]), and contributed to VCO₂[E]. Thus, VCO₂[E] overestimated VCO₂/br (%error) by the amount of rebreathing, which was exacerbated by largerVD _INSTR (increased VCO₂[I]) or smaller V_T (increased VCO₂[I]-to-VCO₂/br ratio).     

Intra-operative risk and haemodynamic etfects of the CO2-pneumoperitoneum in laparoscopic surgery

The benetits of minimally invasive surgery led to an increasing rate of laparoscopic procedures in older patients. These patients profit most from the p.op. advantages of laparoscopic surgery. On the other hand they often display cardiovascular risks with the intra-operative risk of the CO₂-pneumoperitoneum still under discussion. Methods: The haemodynamic etfects of CO₂-pneumoperitoneum were investigated. Monitoring included cardiac output (CO), central venous pressure (CVP), pulmonary arterial pressure (PAP) and wedge pressure (PAWP), femoral venous pressure (FVP), intra-oesophageal pressure (IEP), systemic vascular resistance (SVR) and transmural right-atrial pressure (TMP), and was performed in a controlled, experimental model. Results: Establishing the pneumoperitoneum caused initially a 35% decrease in CO. SVR, as an indicator of cardiac afterload, increased clearly. The increased intra-abdominal pressure led to a reduction of venous retlux from the periphery and squeezed the venous reservoir within the abdominal cavity. Cardiac preload was altered, too. The elevated cardiac afterload adapted under pneumoperitoneum. After desufflation cardiac output rose far above normal. Conclusions: These results indicate a strong cardiac stress after insufflation and desufflation. This is caused by the increased intra-abdominal pressure rather than by systemic etfects of resorbed CO₂. Laparoscopic procedures in patients with clinical signs of cardiovascular insufficiency should only be performed with substantial intra-operative monitoring. Otherwise low pressure pneumoperitoneum and/or pressure and gasless laparoscopy could be considered.     

Association of body weight with total mortality and with ICD shocks among survivors of ventricular fibrillation in out-of-hospital cardiac arrest

AIM: Studies have shown an association between obesity and total mortality among people with and without coronary artery disease. This study reviews outcomes among obese survivors of ventricular fibrillation in out-of-hospital cardiac arrest. METHODS: All survivors of ventricular fibrillation in out-of-hospital cardiac arrest who presented in Rochester, MN from November 1990 to September 2006 were included and classified by body weight. Implantable cardioverter defibrillator shocks administered were determined by review of subsequent device interrogations. RESULTS: Among a study population of 226, 99 (44%) survived to hospital discharge with neurological recovery. Data to calculate body mass index were available in 213 cases (95%). There was no significant difference in the relative distribution of body weight between hospital survivors and non-survivors, nor in cardioverter defibrillator implantation rates. Mean follow-up was 5.8+/-4.4 years; 5-year survival was 80+/-5%, lower among underweight and normal compared with heavier individuals. The 5-year survival free of implantable cardioverter defibrillator shocks was 61+/-7%, with no weight-based difference in shocks. CONCLUSION: There was no apparent weight-based influence on resuscitation survival after ventricular fibrillation in out-of-hospital cardiac arrest. People of normal or low weight had a lower long-term survival and represent at population high risk from primarily non-cardiac diseases.     

Pre-hospital body surface potential mapping improves early diagnosis of acute coronary artery occlusion in patients with ventricular fibrillation and cardiac arrest

Aims

To determine whether 80-lead body surface potential mapping (BSPM) improves detection of acute coronary artery occlusion in patients presenting with out-of-hospital cardiac arrest (OHCA) due to ventricular fibrillation (VF) and who survived to reach hospital.

Methods and results

Of 645 consecutive patients with OHCA who were attended by the mobile coronary care unit, VF was the initial rhythm in 168 patients. Eighty patients survived initial resuscitation, 59 of these having had BSPM and 12-lead ECG post-return of spontaneous circulation (ROSC) and in 35 patients (age 69 ± 13 yrs; 60% male) coronary angiography performed within 24 h post-ROSC. Of these, 26 (74%) patients had an acutely occluded coronary artery (TIMI flow grade [TFG] 0/1) at angiography. Twelve-lead ECG criteria showed ST-segment elevation (STE) myocardial infarction (STEMI) using Minnesota 9-2 criteria – sensitivity 19%, specificity 100%; ST-segment depression (STD) ≥0.05 mV in ≥2 contiguous leads – sensitivity 23%, specificity 89%; and, combination of STEMI or STD criteria – sensitivity 46%, specificity 100%. BSPM STE occurred in 23 (66%) patients. For the diagnosis of TFG 0/1 in a main coronary artery, BSPM STE had sensitivity 88% and specificity 100% (c-statistic 0.94), with STE occurring most commonly in either the posterior, right ventricular or high right anterior territories.

Conclusion

Among OHCA patients presenting with VF and who survived resuscitation to reach hospital, post-resuscitation BSPM STE identifies acute coronary occlusion with sensitivity 88% and specificity 100% (c-statistic 0.94).     

A New Calibration Method that Compensates for the Effects of O2 and N2 on Infrared CO2 Analysers

Objective. This study evaluates a method for calibrating mainstream CO₂ analysers in which CO₂ partial pressure (P _CO2) is calculated as a function of the outputs of CO₂ and O₂ analysers. Methods. Three mass flow controllers were used to generate 25 different reference mixtures of O₂, N₂ and CO₂. Reference gas mixtures were combinations of P _CO2 = 2, 4, 6, 8, 10 kPa and O₂ partial pressure (P _O2) = 10, 20, 40, 60, 80 kPa (balance N₂). CO₂ and O₂ analyser data were fitted by a calibration equation which took into account the effects of oxygen partial pressure and nonlinearity of the CO₂ analyser. The calibration coefficients were tested in a separate validation data set with a variety of combinations of CO₂ and O₂. Results. Our new calibration method yields a standard deviation of CO₂ measurement error that is significantly lower than a CO₂-only calibration method in the validation data set (0.54% versus 2.72%, P < 0.05). P _CO2 measurement errors produced by the single gas calibration equation are significantly correlated with P _O2 in both the calibration (R = −0.9906, P < 0.05) and validation data sets (R = −0.9642, P < 0.05), but the errors given by our new calibration equation are independent of P _O2 (R = −0.0364, NS, and R = −0.0305, NS, for calibration and validation data sets respectively). Calibration with only CO₂ cannot eliminate the error related to the collision broadening effect of O₂, which in our CO₂ analyser is approximately a 1% underestimation of P _CO2 for every 10 kPa (75 mmHg) increase in P _O2. Conclusions. This study shows that non-dispersive infrared CO₂ analyser readings can be substantially affected by background oxygen. This effect can be corrected for by calibrating the CO₂ analyser with gases containing known proportions of both CO₂ and O₂.     

The SAMe-TT2R2 score and decision-making between a vitamin K antagonist or a non-vitamin K antagonist oral anticoagulant in patients with atrial fibrillation

Oral anticoagulation therapy is essential in patients with atrial fibrillation and clinicians need guidance on decision-making between the vitamin K antagonists (VKA), e.g. warfarin, or non-vitamin K antagonist oral anticoagulants. Observational studies have shown that patients who receive VKA therapy spend a significant percentage of their time with international normalized ratio values outside of the therapeutic range (time in therapeutic range, TTR <60%.) Recently, a clinical score has been developed with commonly encountered clinical features, the SAMe-TT₂R₂ score, to help decision-making with regard to whether a patient is likely to do well, or not, with a VKA. Those with a SAMe-TT₂R₂ score of 0–1 are likely to do well on a VKA, while those with a SAMe-TT₂R₂ score ≥2 are on probability going to achieve suboptimal TTR. In this article, we provide an overview of the main published retrospective and prospective studies that have validated the SAMe-TT₂R₂ score and its value for decision-making in daily clinical practice.     

Improved Accuracy Of Cardiac Output Estimation By The Partial CO2 Rebreathing Method

Objective  This study investigated the accuracy of the NICO monitor equipped with the newer software. Additionally, the effects of the increased dead space produced by the NICO monitor on ventilatory settings were investi- gated. Methods  Forty-two patients undergoing elective aortic reconstruction participated in this prospective, obser- vational study at a university hospital. Cardiac output was continuously monitored using both the NICO monitor and continuous cardiac output (CCO) measured by a pulmonary artery catheter. A NICO monitor equipped with ver. 4.2 software was used for the first 21 patients while a NICO monitor equipped with ver. 5.0 software was used for the rest of␣the patients. Cardiac output measured by bolus thermo- dilution (BCO) at 30 min intervals was used as a reference. Results  The bias ± precision of the NICO monitor was 0.18 ± 0.88 l/min with ver. 4.2 software (n = 182) and 0.18 ± 0.83 l/min with 5.0 software (n = 194). The accuracy of the NICO monitor is comparable to CCO, whose bias ± &!hairsp;precision against BCO is 0.19 ± 0.81 l/min (n = 376). At the␣same level of CO₂ production and minute ventilation, PaCO₂ was lower in the patients monitored by NICO with ver. 5.0 software than patients with ver. 4.2 software. Conclusions  This study demonstrated the improved perfor- mance of the NICO monitor with updated software. The performance of the NICO monitor with ver. 4.2 or later software is similar to CCO. However, the cardiac output measurement did not fulfill the criteria of interchangeability to the cardiac output measurement by bolus thermodilution. Updates to ver. 5.0 attenuated the effects of rebreathing introduced by the NICO monitor without compromising the accuracy of the cardiac output measurement. This study was presented at the Annual Meeting of the American Society of Anesthesiologists, 2004.10.26, Las Vegas, NV, USA. Kotake Y, Yamada T, Nagata H, Suzuki T, Serita R, Katori N, Takeda J, Shimizu H. Improved accuracy of cardiac output estimation by the partial CO₂ rebreathing method.     

Effect of moderate hyperventilation and induced hypertension on cerebral tissue oxygenation after cardiac arrest and therapeutic hypothermia

Aim

Improving cerebral perfusion is an essential component of post-resuscitation care after cardiac arrest (CA), however precise recommendations in this setting are limited. We aimed to examine the effect of moderate hyperventilation (HV) and induced hypertension (IH) on non-invasive cerebral tissue oxygenation (SctO₂) in patients with coma after CA monitored with near-infrared spectroscopy (NIRS) during therapeutic hypothermia (TH).

Methods

Prospective pilot study including comatose patients successfully resuscitated from out-of-hospital CA treated with TH, monitored with NIRS. Dynamic changes of SctO₂ upon HV and IH were analyzed during the stable TH maintenance phase. HV was induced by decreasing PaCO₂ from ∼40 to ∼30 mmHg, at stable mean arterial blood pressure (MAP ∼ 70 mmHg). IH was obtained by increasing MAP from ∼70 to ∼90 mmHg with noradrenaline.

Results

Ten patients (mean age 69 years; mean time to ROSC 19 min) were studied. Following HV, a significant reduction of SctO₂ was observed (baseline 74.7 ± 4.3% vs. 69.0 ± 4.2% at the end of HV test, p < 0.001, paired t-test). In contrast, IH was not associated with changes in SctO₂ (baseline 73.6 ± 3.5% vs. 74.1 ± 3.8% at the end of IH test, p = 0.24).

Conclusions

Moderate hyperventilation was associated with a significant reduction in SctO₂, while increasing MAP to supra-normal levels with vasopressors had no effect on cerebral tissue oxygenation. Our study suggests that maintenance of strictly normal PaCO₂ levels and MAP targets of 70 mmHg may provide optimal cerebral perfusion during TH in comatose CA patients.