Witnessed out-of-hospital cardiac arrest- effects of emergency dispatch recognition

BACKGROUND

Survival from an out-of-hospital cardiac arrest (OHCA) depends on the sequence of interventions in "the chain of survival". If OHCA is recognized in the emergency medical communication centre (EMCC), the proper emergency medical service (EMS) should be dispatched and cardiopulmonary resuscitation (CPR) instructions should be given to a bystander. The study aimed to examine the impact of OHCA recognition in the EMCC on survival rates and the main elements of the chain of survival.

METHODS

Data from the Helsinki University Hospital's registry of OHCA patients between 1997 and 2013 were studied. Altogether, 2054 EMCC-handled and bystander-witnessed OHCA proven events of cardiac origin were analysed.

RESULTS

In 80.5% of the victims, two EMS units were correctly dispatched and the OHCA was classified as recognized. Achieved return of spontaneous circulation (ROSC) and survival to hospital discharge were 49% and 23%, respectively, if cardiac arrest was recognized by the EMCC and 40% and 16% when it was not (P = 0.003 and 0.002). Dispatchers gave CPR instructions in 60% of the recognized OHCA cases. Bystander-performed CPR increased over time and was given in 58% of the recognized OHCAs and also in 17% of the unrecognized events. EMS delays were shorter if OHCA was recognized as opposed to unrecognized (8 min with an IQR 6.5-10 min vs. 9 min with an IQR 6.5-11 min; P = 0.001).

CONCLUSIONS

Recognition of OHCA by the EMCC was significantly associated with an increased rate of bystander-performed CPR, reduced EMS response time, and increased OHCA patient ROSC and survival rates.

Assessment of plasma endostatin to predict acute kidney injury in critically ill patients

BACKGROUND

We evaluated whether plasma endostatin predicts acute kidney injury (AKI), need for renal replacement therapy (RRT), or death.

METHODS

Prospective, observational, multicenter study from 1 September 2011 to 1 February 2012 with data from 17 intensive care units (ICUs) in Finland.

RESULTS

A total of 1112 patients were analyzed. We measured plasma endostatin within 2 h of ICU admission. Early AKI (KDIGO stage within 12 h of ICU admission) was found in 20% of the cohort, and 18% developed late AKI (KDIGO criteria > 12 h from ICU admission). Median (IQR) admission endostatin was higher in the early AKI group, 29 (19.1, 41.9) ng/ml as compared to 22.4 (16.1, 30.1) ng/ml for the late AKI group, and 18 (14.0, 23.6) ng/ml for non-AKI patients (P < 0.001). Endostatin level increased with increasing KDIGO stage. Significantly higher endostatin levels were found in patients with sepsis as compared to those without. Predictive properties for AKI, RRT, and mortality were low with corresponding areas under the receiver operating characteristic curve (AUC) of 0.62, 0.67, and 0.59. Sensitivity analyses among patients with chronic kidney disease or sepsis did not improve the predictive ability of endostatin. Adding endostatin to a clinical AKI prediction model (illness severity score, urine output, and age) insignificantly changed the AUC from 0.67 to 0.70 (P = 0.14).

CONCLUSIONS

Endostatin increases with AKI severity but has limited value as a predictor of AKI, RRT and 90-day mortality in patients admitted to ICU. Moreover, endostatin does not improve AKI risk prediction when added to a clinical risk model.

Quality of cardiopulmonary resuscitation on manikins: on the floor and in the bed

BACKGROUND

In general, in-hospital resuscitation is performed in a bed and out-of-hospital resuscitation on the floor. The surface under the patient may affect the cardiopulmonary resuscitation (CPR) quality; therefore, we evaluated CPR quality (the percentage of chest compressions of correct depth) and rescuer's fatigue (the mean compression depth minute by minute) when CPR is performed on a manikin on the floor or in the bed.

METHODS

Forty-four simulated cardiac arrest scenarios of 10 min were treated by intensive care unit (ICU) nurses in pairs using a 30 : 2 chest compression-to-ventilation ratio. The rescuer who performed the compressions was changed every 2 min. CPR was randomly performed either on the floor or in the bed without a backboard; in both settings, participants kneeled beside the manikin.

RESULTS

A total number of 1060 chest compressions, 44% with correct depth, were performed on the floor; 1068 chest compressions were performed in the bed, and 58% of these were the correct depth. These differences were not significant between groups. The mean compression depth during the scenario was 44.9+/-6.2 mm (mean+/-SD) on the floor and 43.0+/-5.9 mm in the bed (P=0.3). The mean chest compression depth decreased over time on both surfaces (P<0.001), indicating rescuer fatigue, but this change was not different between the groups (P=0.305).

CONCLUSIONS

ICU nurses perform chest compression as effectively on the floor as in the bed. The mean chest compression depth decreases over time, but the surface had no significant effect.

Nationwide survey of resuscitation education in Finland

AIMS

Good-quality cardiopulmonary resuscitation (CPR) is highlighted in the International Resuscitation Guidelines, but clinically the quality of CPR is often poor. Education of CPR has a major role in the primary skills imparted to students. Different methods can be used to teach CPR quality. We evaluated the current status of their usage in Finland institutes teaching students of emergency medicine at different levels.

METHODS

The following institutes were included in an anonymous survey: medical schools (teaching future physicians), universities of applied sciences (paramedics), colleges (emergency medical technicians) and emergency services college (fire-fighters). Hours of teaching theory lessons of CPR and hours of small group training were evaluated. In particular, we focussed on the teaching methods for adequate chest compression rate and depth.

RESULTS

Twenty-one of 30 institutes responded to the questionnaire. The median for hours of theory lessons of CPR was 8h (range: 2-28 h). The median for hours of small group training was 10 (range: 3-40 h). The methods of teaching adequate chest compression rate were instructors' visual estimation in 28.5% of the institutions, watch in 33.3%, metronome in 9.5% and manikins' graphic in 28.5% of institutions. The methods of teaching adequate chest compression depth were instructors' visual estimation in 33.3%, in manikins light indicators in 23.8% and manikins' graphics in 52.3% of institutions.

CONCLUSION

The hours of theoretic lessons and small group training vary widely among different institutes. In one-third of institutions, the instructor's visual estimation was a sole method used to teach adequate chest compression rate and depth. Different technical methods were surprisingly seldom used.

Influence of chest compression rate guidance on the quality of cardiopulmonary resuscitation performed on manikins

AIMS

The adequate chest compression rate during CPR is associated with improved haemodynamics and primary survival. To explore whether the use of a metronome would affect also chest compression depth beside the rate, we evaluated CPR quality using a metronome in a simulated CPR scenario.

METHODS

Forty-four experienced intensive care unit nurses participated in two-rescuer basic life support given to manikins in 10min scenarios. The target chest compression to ventilation ratio was 30:2 performed with bag and mask ventilation. The rescuer performing the compressions was changed every 2min. CPR was performed first without and then with a metronome that beeped 100 times per minute. The quality of CPR was analysed with manikin software. The effect of rescuer fatigue on CPR quality was analysed separately.

RESULTS

The mean compression rate between ventilation pauses was 137+/-18compressions per minute (cpm) without and 98+/-2cpm with metronome guidance (p<0.001). The mean number of chest compressions actually performed was 104+/-12cpm without and 79+/-3cpm with the metronome (p<0.001). The mean compression depth during the scenario was 46.9+/-7.7mm without and 43.2+/-6.3mm with metronome guidance (p=0.09). The total number of chest compressions performed was 1022 without metronome guidance, 42% at the correct depth; and 780 with metronome guidance, 61% at the correct depth (p=0.09 for difference for percentage of compression with correct depth).

CONCLUSIONS

Metronome guidance corrected chest compression rates for each compression cycle to within guideline recommendations, but did not affect chest compression quality or rescuer fatigue.

The effects of changes to the ERC resuscitation guidelines on no flow time and cardiopulmonary resuscitation quality: A randomised controlled study on manikins

AIM OF THE STUDY

The European Resuscitation Council (ERC) guidelines changed in 2005. We investigated the impact of these changes on no flow time and on the quality of cardiopulmonary resuscitation (CPR).

MATERIALS AND METHODS

Simulated cardiac arrest (CA) scenarios were managed randomly in manikins using ERC 2000 or 2005 guidelines. Pairs of paramedics/paramedic students treated 34 scenarios with 10min of continuous ventricular fibrillation. The rhythm was analysed and defibrillation shocks were delivered with a semi-automatic defibrillator, and breathing was assisted with a bag-valve-mask; no intravenous medication was given. Time factors related to human intervention and time factors related to device, rhythm analysis, charging and defibrillation were analysed for their contribution to no flow time (time without chest compression). Chest compression quality was also analysed.

RESULTS

No flow time (mean+/-S.D.) was 66+/-3% of CA time with ERC 2000 and 32+/-4% with ERC 2005 guidelines (P<0.001). Human factor interventions occupied 114+/-4s (ERC 2000) versus 107+/-4s (ERC 2005) during 600-s scenarios (P=0.237). Device factor interventions took longer using ERC 2000 guidelines: 290+/-19s versus 92+/-15s (P<0.001). The total number of chest compressions was higher with ERC 2005 guidelines (808+/-92s versus 458+/-90s, P<0.001), but the quality of CPR did not differ between the groups.

CONCLUSIONS

The use of a single shock sequence with guidelines 2005 has decreased the no flow time during CPR when compared with guidelines 2000 with multiple shocks.

Intensive care of the elderly in Finland

BACKGROUND

The ageing of the population will increase the demand for health care resources. The aim of this study was to determine how age affects resource consumption and outcome of intensive care in Finland.

METHODS

Data on 79,361 admissions to 26 Finnish intensive care units (ICUs) during the years 1998-2004 were analysed. The severity of illness was measured using Simplified Acute Physiology II scores and the intensity of care using Therapeutic Intervention Scoring System scores.

RESULTS

The median age was 62 years; 8.9% of patients were aged 80 years or over. The hospital mortality rate was 16.2% in the overall patient population, but 28.4% in patients aged 80 years or over. Old age was an independent risk factor for hospital mortality. The mean intensity of care was at its highest in the age groups 60-69, 70-74 and 75-79 years. It was notably lower for patients aged 80 years or over. If the need for intensive care remains unchanged in each age group, the change in the age distribution of the Finnish population will increase the demand for ICU beds by 19% by the year 2020 and by 25% by the year 2030.

CONCLUSION

The hospital mortality rate increases with increasing age. The mean intensity of care is lower for the oldest patients than for patients aged less than 80 years. The ageing of the population will probably cause a remarkable increase in the need for intensive care in the near future.

Propofol causes more hypotension than etomidate in patients with severe aortic stenosis: a double-blind, randomized study comparing propofol and etomidate

BACKGROUND

Vasodilatation and hypotension are thought to be harmful in patients with severe aortic stenosis. Etomidate is preferred to propofol for anaesthesia induction in haemodynamically unstable patients, but may disturb cortisol synthesis. We assessed the haemodynamic effects of etomidate vs. propofol as anaesthesia induction agents, and the effects of these drugs on cortisol concentrations, in patients with severe aortic stenosis. The main end-point of the study was the incidence of hypotension.

METHODS

Sixty-six patients with severe aortic stenosis scheduled for elective aortic valve replacement were enrolled in the study. The patients were randomized to receive either propofol or etomidate for induction of anaesthesia. Haemodynamic parameters, i.e. mean arterial pressure (MAP), pulmonary capillary wedge pressure (PCWP) and cardiac index (CI), were measured. If MAP decreased below 70 mmHg for more than 30 s, phenylephedrine was administered. Serum cortisol concentrations were also measured.

RESULTS

MAP decreased in all patients (P < 0.001). MAP decreased to a greater extent in patients receiving propofol than in those receiving etomidate (P = 0.006). Patients receiving propofol needed phenylephedrine more often than those receiving etomidate (20/30 vs. 8/30, P = 0.002). CI and PCWP decreased in both groups (P < 0.001), with no difference between the groups. Patients receiving etomidate had a lower serum cortisol concentration immediately after the operation than those receiving propofol (P < 0.001), but no differences between the groups were observed on the first post-operative morning.

CONCLUSION

Propofol is twice as likely as etomidate to evoke hypotension in anaesthesia induction of patients with severe aortic stenosis; however, etomidate transiently decreases post-operative serum cortisol concentrations.

Excess mortality in winter in Finnish intensive care

BACKGROUND

In the general population, mortality from acute myocardial infarctions, strokes and respiratory causes is increased in winter. The winter climate in Finland is harsh. The aim of this study was to find out whether there are seasonal variations in mortality rates in Finnish intensive care units (ICUs).

METHODS

We analysed data on 31,040 patients treated in 18 Finnish ICUs. We measured severity of illness with acute physiology and chronic health evaluation II (APACHE II) scores and intensity of care with therapeutic intervention scoring system (TISS) scores. We assessed mortality rates in different months and seasons and used logistic regression analysis to test the independent effect of various seasons on hospital mortality. We defined 'winter' as the period from December to February, inclusive.

RESULTS

The crude hospital mortality rate was 17.9% in winter and 16.4% in non-winter, P = 0.003. Even after adjustment for case mix, winter season was an independent risk factor for increased hospital mortality (adjusted odds ratio 1.13, 95% confidence interval 1.04-1.22, P = 0.005). In particular, the risk of respiratory failure was increased in winter. Crude hospital mortality was increased during the main holiday season in July. However, the severity of illness-adjusted risk of death was not higher in July than in other months. An increase in the mean daily TISS score was an independent predictor of increased hospital mortality.

CONCLUSION

Severity of illness-adjusted hospital mortality for Finnish ICU patients is higher in winter than in other seasons.

Red blood cell and tissue water content in experimental thermal injury

Oedema formation and changes in local blood flow are known phenomena in burns. The relationship between these two is not clearly described. The aim of this study was firstly to examine both the contents of red blood cells and tissue water in skin and subcutaneous fat after experimental burns of different depths in pigs, and secondly, to confirm our recent findings of the increased dielectric constant of skin and subcutaneous fat reflecting considerable oedema formation, especially in fat after thermal injury.

METHODS

Superficial, partial and full thickness contact burns were created to pigs and followed for 24h. Radioactive Cr-51 labelling of red cells was used to estimate the number of red cells in tissue, and the absolute amount of water was determined by lyophilization.

RESULTS

A decreased number of labelled red cells in skin and an increase in tissue water in subcutaneous fat were found regardless of burn depth. The highest water amount in fat was found in the partial thickness burns.

CONCLUSION

All burn depths resulted in a diminished number of labelled red blood cells in skin and a significant increase in the absolute water amount in subcutaneous fat at 24h post injury. The findings in fat support our recent findings of highly elevated dielectric constants measured by the new in vivo method of dielectric measurements.

The proportion of intensive care unit admissions related to alcohol use: a prospective cohort study

BACKGROUND

Alcohol abuse is a risk factor for serious illnesses, and a history of chronic alcohol abuse adversely affects the outcome of critically ill patients. It is not known what proportion of intensive care unit (ICU) admissions is related to alcohol use. Therefore, we investigated the proportion of emergency admissions related to alcohol.

METHODS

A prospective cohort study was conducted in a university hospital ICU. All adult patients (n = 893) who underwent emergency admission to our ICU during a period of 1 year were studied.

RESULTS

The admitting physician determined whether there was a relationship between alcohol use and admission. ICU and hospital mortality and ICU length of stay (LOS) were recorded. The Therapeutic Intervention Scoring System (TISS) was used for ICU resource use estimation. There was a relationship between alcohol use and admission in 24% (215/893) of admissions and, in 156/893 admissions (17.5%), this seemed to be definite. ICU LOS was 1.2 days (0.7; 2.3) (median; interquartile range) for alcohol-related and 1.8 days (0.9; 3.6) for other admissions (P < 0.001). Patients with alcohol-related admissions consumed 17.8% of ICU patient-days and 18.7% of all accumulated TISS scores. ICU (8.8 vs. 10.5%, P = 0.603) and hospital (19.1 vs. 20.2%, P = 0.769) mortalities were no different between alcohol-related and other admissions.

CONCLUSION

ICU admission is very often related to long-term chronic and/or occasional alcohol use.

Impact of gender on treatment and outcome of ICU patients

BACKGROUND

Gender modifies immunologic responses caused by severe trauma or critical illness. The aim of this study was to investigate the impact of gender on hospital mortality, length of intensive care unit (ICU) stay, and intensity of care of patients treated in ICUs.

METHODS

Data on 24,341 ICU patients were collected from a national database. We measured severity of illness with Acute Physiology and Chronic Health Evaluation II (APACHE II) scores and intensity of care with Therapeutic Intervention Scoring System (TISS) scores. We used logistic regression analysis to test the independent effect of gender on hospital mortality. We compared the lengths of ICU stay and the intensity of care of men and women.

RESULTS

Male gender was associated with increased hospital mortality among postoperative ICU patients [adjusted odds ratio 1.33 (95% confidence interval 1.12-1.58, P = 0.001)] but not among medical patients [adjusted odds ratio 1.02 (95% confidence interval 0.92-1.13, P = 0.74)]. Male gender was associated with an increased risk of death particularly in the oldest age group (75 years or older) and among the patients with relatively low APACHE II scores (<16). Mean length of ICU stay was 3.2 days for men and 2.6 days for women (P < 0.001). Male patients comprised 61.7% of the study population but consumed 66.0% of days in intensive care.

CONCLUSION

Male gender contributes to poor outcome in postoperative ICU patients. Approximately two-thirds of ICU resources are consumed by male patients.

Microdialysis for detection of dynamic changes in tissue histamine levels in experimental thermal injury

Histamine is an important mediator contributing to oedema formation after thermal injury. Tissue histamine concentrations have been previously determined by analyzing tissue biopsies. The microdialysis method enables continuous collection of samples from the extracellular tissue fluid. In this experimental burn study on pigs samples from the extracellular fluid for histamine analysis were collected from superficial, partial thickness and full thickness burn sites during a 24-h period. There was a burn depth-related increase in histamine concentrations during the first 2 h post injury. Deep burns induced a more profound initial increase in tissue histamine concentration than the partial thickness and superficial burns. Histamine concentrations at all burn sites declined until 12 h post injury. There was a second rise in tissue histamine concentrations between 12 and 24 h post injury without a rise in plasma histamine concentrations. Histamine concentrations at all burn sites were higher than at the non-burned control sites. The microdialysis technique is an easily applicable method of collecting on-line samples from burned tissue. This method provides a useful tool in investigating the effects of different treatment modalities on the secretion of substances into interstitial fluid within burned tissue.

Lack of effect of ranitidine on gastric luminal pH and mucosal PCO2 during the first day in the ICU

BACKGROUND

Histamine(2) (H(2))-blocking agents can attenuate intragastric CO(2)-production by reducing gastric acid secretion and preventing the interaction between H(+) and bicarbonate. However, gastric acid production may be impaired in acute circulatory failure due to poor mucosal perfusion, and H(2)-blockade could further impair mucosal perfusion.

METHODS

Forty patients with acute circulatory and/or respiratory failure, age 61 +/- 16 years (mean +/- SD), APACHE II score 21 +/- 7, and SOFA score 8 +/- 3, received randomly either ranitidine, 50 mg (R) or placebo (P) every 8 h. Gastric intraluminal pH (gpH; antimony probe with external reference electrode) and mucosal pCO(2) (prCO(2), semicontinuous air-tonometry) were measured during 24 h, and blood gases were taken at 6-h intervals.

RESULTS

Gastric intraluminal pH was 4.3 +/- 2.4 in P and 5.1 +/- 1.6 in R (NS). Mean prCO(2) was 6.8 +/- 2.7 kPa in P and 7.4 +/- 2.1 kPa in R, and mucosal-arterial pCO(2) gradient (Delta pCO(2)) was 2.2 +/- 2.9 kPa and 2.4 +/- 2.4 kPa, respectively (NS). Within-patient variabilities of gpH and prCO(2) were not influenced by ranitidine. A posthoc analysis revealed that non-survival in R was associated with a low mucosal pHi after 24 h (P = 0.002). This was explained by a low arterial pH but not by differences in gpH or prCO(2).

CONCLUSION

In acute respiratory and circulatory failure, H(2) blockade has an inconsistent impact on gpH and does not reduce variabilities of gpH or prCO(2).

The progression of burn depth in experimental burns: a histological and methodological study

This study was designed to create a reproducible model for experimental burn wound research in pigs. Previously, the thicker paraspinal skin has been used. We used the more human-like ventral skin to create burns of different depths. Contact burns were created to 11 pigs using a brass plate heated to 100 degrees C in boiling water. Different contact times were used to create burns of different depths. In pigs 1-6, the follow-up time was 72 h and in pigs 7-11 24 h. Burn depth was determined by histology. Histologically, samples were classified into five anatomical layers: epidermis, upper one-third of the dermis, middle third of the dermis, deepest third of the dermis and subcutaneous fat. The location of both thromboses and burn marks were evaluated, respectively. The 1 s contact time lead to a superficial thermal injury, 3 s to a partial thickness and 9 s to a full thickness injury. A progression of burn depth was found until 48 h post-injury. The intra-observer correlation after repeated histological analyses of burn depths by the same histopathologist and the repeatability of burn depth creation yielded kappa coefficients 0.83 and 0.92, respectively.

CONCLUSION

a reproducible burn model for further research purposes was obtained.

Dobutamine compensates deleterious hemodynamic and metabolic effects of vasopressin in the splanchnic region in endotoxin shock

BACKGROUND

Vasopressin is a potent vasopressor in septic shock, but it may impair splanchnic perfusion. We compared the effects of vasopressin alone and in combination with dobutamine on systemic and splanchnic circulation and metabolism in porcine endotoxin shock.

METHODS

Twelve pigs were randomized to receive either vasopressin (VASO, n = 6) or vasopressin in combination with dobutamine (DOBU, n = 6) during endotoxin shock (E. coli endotoxin infusion). Endotoxin infusion rate was increased to induce hypotension after which vasoactive drugs were started. We aimed to keep systemic mean arterial pressure (MAP) >70 mmHg by vasopressin; the goal of dobutamine infusion was to prevent decrease in cardiac output often associated with vasopressin infusion. Regional blood flows, oxygen delivery and consumption, arterial and regional lactate concentrations were measured.

RESULTS

Mean arterial pressure >70 mmHg was achieved in both the VASO and DOBU groups. After the primary decrease of cardiac output by vasopressin, systemic blood flow remained stable in vasopressin-treated animals. However, vasopressin as a monotherapy decreased portal venous blood flow. This was prevented by dobutamine. Vasopressin also induced splanchnic lactate release and arterial hyperlactatemia, which were not observed when dobutamine was combined with vasopressin.

CONCLUSION

Dobutamine prevents adverse hemodynamic and metabolic effects of vasopressin in septic shock.

Pressure-volume relationships in acute lung injury: methodological and clinical implications

BACKGROUND

Pressure-volume relationships (PV curves) are the only available method for bedside monitoring of respiratory mechanics. Alveolar recruitment modifies the results obtained from the PV curves. We hypothesized that method-related differences may influence PV-curve guided ventilatory management.

METHODS

Twelve acute lung injury (ALI) patients [PaO2/FiO2 13.0 +/- 1.5 kPa (97.6 +/- 11.3 mmHg), bilateral pulmonary infiltrates] were studied. Two PV curves [one at variable, and another at constant level of positive end-expiratory pressure (PEEP)] were obtained from each patient using constant inspiratory flow and end-inspiratory and -expiratory occlusions. Upper and lower inflection points (UIP, LIP) were estimated. Recruitment due to PEEP and during inflation was assessed by respiratory inductive plethysmography (RIP).

RESULTS

(1) Pressure-volume curves at constant PEEP tended to provide higher LIP values compared with curves at variable PEEP (mean difference +/- SEM 5.1 +/- 1.9 cmH2O); and (2) recruitment occurred throughout the PV curve with no relationship with LIP or UIP.

CONCLUSION

Pressure-volume curves obtained using variable PEEP translate a different physiological reality and seem to be clinically more relevant than curves constructed at constant PEEP. If curves constructed at constant PEEP are used to set the ventilator, unnecessarily high PEEP levels may be used. Respiratory inductive plethysmography technology may be used for monitoring of recruitment at the bedside.

Results and costs of intensive care in a tertiary university hospital from 1996-2000

BACKGROUND

Costs of intensive care may be 20% of all hospital costs. Population aging likely increases the demand for intensive care services, while health care has financial limitations. Therefore data about outcome and costs of intensive care are needed. We studied changes in patient characteristics, outcome, intensity of care and costs of intensive care in a tertiary university hospital in Finland.

METHODS

We analyzed retrospectively data of patients admitted to the ICU between 1 January 1996 and 31 December 2000 using the patient data management system. Postoperative and ICU patients were analyzed separately. Data included age, Apache II score, cause of intensive care admission, length and intensity of ICU care. ICU, hospital and 6-month mortality were analyzed. Intensity of care was assessed by TISS points and the annual costs of intensive care were evaluated.

RESULTS

The number of ICU admissions from 1996-2000 was 11,323. The proportions of ICU and postoperative patients were 39% and 61%, respectively. The mean age of the patients did not change. The mean Apache II score increased over time both in the ICU and postoperative patients. There was no change in crude hospital mortality. Total ICU costs decreased from 8,660,000 euros (in 1997) to 7,480,000 euros (in 2000). In the ICU patients, the costs of hospital survival decreased towards the end of the study period.

CONCLUSIONS

We treated more severely ill patients with unchanged outcome but at lower costs towards the end of the study period. Costs of intensive care are not necessarily increasing.

Dopexamine reverses colonic but not gastric mucosal perfusion defects in lethal endotoxin shock

BACKGROUND

Whilst dopexamine appears to increase overall splanchnic blood flow in postoperative and septic patients, the effects on gastric mucosal perfusion are controversial and based on concomitantly increasing mucosal to arterial PCO(2) gradients (PdCO(2)). We hypothesized that dopexamine alters splanchnic blood flow distribution and metabolism during experimental endotoxin shock and modifies the inflammatory response induced by endotoxin.

METHODS

In an experiment with anaesthetized normovolaemic, normoventilated pigs, 21 animals were randomized into: (i). subacute lethal endotoxin shock for 14 h (n=7 at baseline); (ii). endotoxin shock with dopexamine infusion (aiming to exceed baseline cardiac output, n=7); or (iii). controls (n=7). Regional blood flow and metabolism were monitored.

RESULTS

Endotoxin produced a hypodynamic phase followed by a normo/hyperdynamic, hypotensive phase. Despite increasing systemic blood flow in response to dopexamine, proportional splanchnic blood flow decreased during the hypodynamic phase. Dopexamine gradually decreased fractional coeliac trunk flow, while fractional superior mesenteric arterial flow increased. Dopexamine induced early arterial hyperlactataemia and augmented the gastric PdCO(2) gradient while colonic luminal lactate release and colonic PdCO(2) gradient were reversed. Dopexamine did not modify the inflammatory response as evaluated by arterial IL-1beta and IL-6 concentrations.

CONCLUSIONS

Dopexamine protects colonic, but not gastric mucosal epithelium in experimental endotoxin shock. This may be related to redistribution of blood flow within the splanchnic circulation.

Myocardial function and haemodynamics in extensive burn trauma: evaluation by clinical signs, invasive monitoring, echocardiography and cytokine concentrations. A prospective clinical study

BACKGROUND

The objectives of this study were to (1). describe the haemodynamic profile of patients with extensive burns during the early fluid resuscitation phase, (2). evaluate myocardial performance by invasive monitoring and echocardiography and (3). analyze the relations between serum cytokine (IL-6, IL-8, TNF) and natriuretic peptide (ANP, BNP) concentrations and myocardial function in these patients.

METHODS

Prospective, clinical study in a tertiary care burn centre. Invasive haemodynamic measurements including a pulmonary artery catheter, echocardiography, blood samples for cytokine and atriopeptide analyses. The follow-up time was up to 72 h postinjury.

RESULTS

According to echocardiography, patients were hypovolaemic despite aggressive (median 7,9 ml kg(-1) h(-1), range 3.3-11.7) fluid resuscitation and adequate urine output (median 0.9 ml kg(-1) h(-1), range 0.46-1.35) during the first day postinjury. There were no consistent findings of hyperlactatemia, metabolic acidosis or low mixed venous oxygen saturations. Daily highest and lowest values of cardiac index and stroke volume index increased and the lowest and highest values of systemic vascular resistance decreased. Cardiac performance (stroke volume index) improved during the study period even though there were no initial signs of myocardial depression in echocardiography. Three patients received a dobutamine infusion based on clinical judgement. There was no consistent association between haemodynamic changes and plasma cytokine concentrations.

CONCLUSION

Persisting hypovolaemia is evident in the resuscitation phase of extensive burns despite aggressive fluid therapy and the lack of classic signs of hypoperfusion. Cardiac performance improves during the first days after extensive burn injury without association with plasma cytokine profile.

High-dose thiopental in the treatment of refractory status epilepticus in intensive care unit

The authors studied prospectively the effects of thiopental anesthesia on seizure control, hemodynamics, and the course of intensive care in 10 patients with refractory status epilepticus. Clinical and electrophysiological seizures were terminated in every patient. Hemodynamically, thiopental was well tolerated, but slow recovery from anesthesia prolonged the need for intensive care.

Paramedic helicopter emergency service in rural Finland - do benefits justify the cost?

BACKGROUND

The benefit of the Helicopter Emergency Medical Service (HEMS) is not well documented. The aim of our study was to investigate the potential health benefits of HEMS, and their relation to cost of the service in a rural area in Finland. We also evaluated whether the patient benefit is due to early Advanced Life Support (ALS) procedures performed on-scene, or due to rapid transport of patients to definitive care.

METHODS

We reviewed all helicopter missions during 1 year (1999). Based on given prehospital care, we divided these missions into various categories. At the time of discharge, in-hospital records were reviewed for patients who received prehospital ALS care in order to estimate the potential benefit of HEMS.

RESULTS

There were 588 missions. In 40% (n = 233/588), the mission was aborted. ALS care was given on-scene to 206 patients. It was estimated that in this group lives of three patients (1.5%) were saved, and 42 (20%) patients, mostly with cardiovascular disease, otherwise benefited from the service. The majority (84%) of the patients benefited from on-scene ALS procedures only. The cost for beneficial mission was euro 28 444.

CONCLUSION

A minority of all patients did benefit from HEMS. Benefit was related to early ALS care and the cost per beneficial mission was 28 444.

Gastric mucosal systemic partial pressure of carbon dioxide (PCO(2)) gradient in experimental endotoxin shock in swine--comparison of two methods

OBJECTIVES

Clinically applicable methods for continuous monitoring of visceral perfusion/metabolism do not exist. Gastric mucosal end-tidal partial pressure of carbon dioxide (PCO(2)) gradient has been used, but it has limitations, especially in patients with lung injury and increased dead space ventilation. We studied the agreement between gastric mucosal end-tidal (DPCO(2gas)) and gastric mucosal arterial PCO(2) (D((t-a))PCO(2)) gradients, and especially the effect of dead space ventilation (V(d)/V(t) ratio) on the agreement. We hypothesized that DPCO(2gas) can be used as a semi-continuous indicator of mucosal arterial PCO(2) gradient in sepsis.

DESIGN

A randomized, controlled animal experiment.

SETTING

National laboratory animal center.

INTERVENTIONS

Twelvehour infusion of endotoxin in landrace pigs.

MEASUREMENTS AND RESULTS

We measured end-tidal PCO(2) continuously, gastric mucosal PCO(2) every 10 min (gas tonometry) and arterial PCO(2) every 120 min. Carbon dioxide production and the V(d)/V(t) ratio were determined by indirect calorimetry. In the endotoxin group ( n=7) cardiac index increased and systemic vascular resistance decreased. Endotoxemia increased dead space ventilation by 27% ( p=0.001). Both DPCO(2gas) and D((t-a))PCO(2)increased significantly in the endotoxin group ( p<0.0001 and p=0.049, respectively). Control animals remained stable throughout the experiment. When we compared DPCO(2gas) and D((t-a))PCO(2)(Bland-Altman analysis), the bias and precision were 0.9 and 0.9 kPa in the control group and 2.0 and 2.2 kPa in the endotoxin group, respectively. The disagreement between DPCO(2gas) and D((t-a))PCO(2) increased as the V(d)/V(t) ratio increased.

CONCLUSIONS

DPCO(2gas) is a clinically applicable method for continuous monitoring of visceral perfusion/metabolism. Septic lung injury and increased dead space ventilation decrease the accuracy of the method, but this may not be clinically important.

Attenuation of lung inflammation by adrenergic agonists in murine acute lung injury

BACKGROUND

Acute lung injury leading to a systemic inflammatory response greatly increases mortality in critically ill patients. Cardiovascular management of these patients frequently involves beta-adrenergic agonists. These agents may alter the inflammatory response. Therefore, the authors tested the hypothesis that beta-adrenergic agonists alter the pulmonary inflammatory response during acute lung injury in mice.

METHODS

Five-week-old CD-1 mice received continuous infusions of 10 microg x kg(-1) x min(-1) dobutamine, 6 microg x kg(-1) x min(-1) dopexamine, or vehicle via intraperitoneal mini osmotic pumps, followed immediately by intratracheal instillation of approximately 2 microg/kg endotoxin (or phosphate-buffered saline control). Six hours later the mice were killed, and lung lavage was performed. Interleukin-6 and -10 concentrations in lung homogenates were measured using enzyme-linked immunosorbent assay. Interleukin-6 and macrophage inflammatory protein-2 mRNA was measured using reverse-transcription polymerase chain reaction.

RESULTS

Interleukin-6 protein and mRNA significantly increased after intratracheal endotoxin (P < 0.001), and the fraction of neutrophils in lung lavage fluid increased in endotoxin-treated (41 +/- 25%) versus control mice (2 +/- 4%, P < 0.05). Treatment of endotoxic mice with dobutamine significantly decreased interleukin-6 protein (P < 0.05) and mRNA (P < 0.05) expression. Dopexamine had similar but less pronounced effects. Dobutamine decreased interleukin-10 expression, whereas dopexamine did not. In endotoxemic mice, both dobutamine and dopexamine decreased induction of macrophage inflammatory protein-2 mRNA (P < 0.05) and reduced the fraction of neutrophils in lung lavage fluid (P < 0.05).

CONCLUSIONS

In endotoxin-induced acute lung injury, beta-adrenergic agonists can significantly decrease proinflammatory cytokine expression, decrease induction of chemokine mRNA, and decrease the resultant neutrophil infiltrate in the lung.

Gastric mucosal end-tidal PCO2 difference as a continuous indicator of splanchnic perfusion

Gastric mucosal and arterial blood PCO2 must be known to assess mucosal perfusion by means of gastric tonometry. As end-tidal PCO2 (PE'CO2) is a function of arterial PCO2, the gradient between PE'CO2 and gastric mucosal PCO2 may reflect mucosal perfusion. We studied the agreement between two methods to monitor gut perfusion. We measured the difference between gastric mucosal PCO2 (air tonometry) and PE'CO2 (= DPCO2gas) and the difference between gastric mucosal PCO2 (saline tonometry) and arterial blood PCO2 (= DPCO2sal) in 20 patients with or without lung injury. DPCO2gas was greater than DPCO2sal but changes in DPCO2gas reflected changes in DPCO2sal. The bias between DPCO2gas and DPCO2sal was 0.85 kPa and precision 1.25 kPa. The disagreement between DPCO2gas and DPCO2sal increased with increasing dead space. We propose that the disagreement between the two methods studied may not be clinically important and that DPCO2gas may be a method for continuous estimation of splanchnic perfusion.

Stress test and gastric-arterial PCO2 measurement improve prediction of successful extubation

OBJECTIVE

Correct early prediction of successful extubation decreases morbidity and mortality. The use of single time point measurements and surrogate markers of true extubation success limits weaning studies. Our aim was to determine whether a "stress test" improves prediction of extubation outcome and to determine the most predictive variables.

DESIGN

Observational study.

SETTING

Intensive care unit of a teaching hospital.

PATIENTS

A convenience sample of 68 patients judged to be ready for extubation.

INTERVENTIONS

We decreased pressure support from 5 to 0 cm H2O for 1 hr before extubation (stress test) while patients were on 5 cm H2O continuous positive airway pressure.

MEASUREMENTS AND MAIN RESULTS

We measured respiratory frequency, tidal volume, ratio of respiratory frequency to tidal volume (f/VT), airway occlusion pressure after onset of inspiration (P0.1), and gastric-arterial PCO2 (deltaPg-aCO2 both on 5 cm H2O and 0 cm H2O pressure support. Then all patients were extubated. Failure of extubation was defined as reintubation within 24 hrs. Seventeen patients (25%) failed extubation. With pressure support of 5 cm H2O and continuous positive airway pressure of 5 cm H2O, most predictors were not different between patients who failed and patients who were successfully extubated. After the stress test, deltaPg-aCO2 was 2 (-5; 15) mm Hg (median; quartiles) in successfully extubated patients vs. 28 (-9; 48) in failures (p = .0003), tidal volume was 473 (387; 558) vs. 400 (323; 435) mL (p = .02), and P0.1 was 2.8 (2; 4.1) vs. 4.1 (2.7; 5.3) mm Hg (p = .03), respectively. The stress test increased specificity of deltaPg-aCO2 from 0.45 to 0.94 and positive predictive value from 0.85 to 0.97. The specificity and positive predictive values for f/VT after the stress test were 0.23 and 0.78.

CONCLUSIONS

A simple stress test improves prediction of extubation outcome. deltaPg-aCO2 has superior specificity and positive predictive value compared with other variables. The use of true clinical outcome (i.e., extubation) instead of the use of surrogate markers (e.g., tachypnea) distinguishes these results from previous studies.

Gastric-arterial PCO2 gradient does not reflect systemic and splanchnic hemodynamics or oxygen transport after cardiac surgery

Gastric mucosal-arterial PCO2 gradient (P(g-a)CO2) is used to assess splanchnic perfusion and oxygenation. We evaluated whether P(g-a)CO2 reflects whole body (Q) and splanchnic (Qsp) blood flow, oxygen delivery (DO2) and consumption (VO2) after coronary artery by pass graft (CABG) operation. Thirty patients received dobutamine or dopexamine to increase cardiac index, 15 patients enalapril or sodium nitroprusside to lower blood pressure, and 30 patients were controls. We measured Q, Qsp (hepatic vein catheter and indocyanine green), and gastric mucosal PCO2 (nasogastric tonometer) before and after interventions. Multiple linear regression model showed that none of the changes in Q, Qsp, and splanchnic or systemic DO2 and VO2 significantly explained changes in P(g-a)CO2 (deltaP(g-a)CO2). All independent variables together explained only 7% of deltaP(g-a)CO2. Increased splanchnic blood flow (0.65 +/- .19 vs. 0.94 +/- .31 L/min/m2, P < 0.001) and increased splanchnic DO2 (101 +/- 28 vs. 143 +/- 42 mL/min/m2, P < 0.001) during catecholamine infusions were associated with increased P(g-a)CO2 (8 +/- 8 vs. 11 +/- 7 mmHg, P = 0.003). P(g-a)CO2 does not reflect whole body or splanchnic blood flow, DO2 or VO2 after CABG operations. The physiology of P(g-a)CO2 is complex and therefore it is difficult for clinicians to interpret changes in gastric mucosal-arterial PCO2 gradient in individual patients after cardiac surgery.

Could anti-inflammatory actions of catecholamines explain the possible beneficial effects of supranormal oxygen delivery in critically ill surgical patients?

OBJECTIVE

To evaluate the literature regarding antiinflammatory actions of cytokines, evaluate randomized controlled trials (RCTs) of supranormal oxygen delivery, and suggest alternative mechanism(s) for possible beneficial effects of supranormal oxygen delivery in critically ill surgical patients.

DESIGN

Literature review using Medline and review of selected illustrative studies.

MAIN RESULTS

Catecholamines (epinephrine, norepinephrine, isoproterenol, and dopamine) in general inhibit tumor necrosis factor-alpha (TNF) production and may enhance interleukin-6 (IL-6) and IL-10 production. Phosphodiesterase inhibitors also inhibit TNF and may enhance IL-10. All studies used models (cell, animal, or humans infused with endotoxin) of sepsis. RCTs of supranormal oxygen delivery show decreased mortality in high-risk surgical patients; however, prevention or reversal of tissue hypoxia may not be the mechanism of benefit. Antiinflammatory effects of catecholamines are a potential and, to date, unexplored mechanism of the benefit of supranormal oxygen delivery in critically ill surgical patients.

CONCLUSIONS

Catecholamines may modulate cytokine response beneficially and could be a mechanism of decreased morbidity and mortality of supranormal oxygen delivery in high-risk surgical patients.

Acute respiratory distress syndrome: frequency, clinical course, and costs of care

OBJECTIVE

To define the occurrence rate of acute respiratory distress syndrome (ARDS) using established criteria in a well-defined general patient population, to study the clinical course of ARDS when patients were ventilated using a "lung-protective" strategy, and to define the total costs of care.

DESIGN

A 3-yr (1993 through 1995) retrospective descriptive analysis of all patients with ARDS treated in Kuopio University Hospital.

SETTING

Intensive care unit in the university hospital.

PATIENTS

Fifty-nine patients fulfilled the definition of ARDS: Pao2/Fio2 <200 mm Hg (33.3 kPa) during mechanical ventilation and bilateral infiltrates on chest radiograph.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

With a patient data management system, the day-by-day data of hemodynamics, ventilation, respiratory mechanics, gas exchange, and organ failures were collected during the period that Pao2/Fio2 ratio was <200 mm Hg (33.3 kPa). The frequency of ARDS was 4.9 cases/100,000 inhabitants/yr. Pneumonia and sepsis were the most common causes of ARDS. Mean age was 43+/-2 yrs. At the time of lowest Pao2/Fio2, the nonsurvivors had lower arterial and venous oxygen saturations and higher arterial lactate than survivors, whereas there were no differences between the groups in other parameters. Multiple organ dysfunction preceded the worst oxygenation in both the survivors and nonsurvivors. The intensive care mortality was 37%; hospital mortality and mortality after a minimum 8 months of follow-up was 42%. The most frequent cause of death was multiple organ failure. The effective costs of intensive care per survivor were US $73,000.

CONCLUSIONS

The outcome of ARDS is unpredictable at the time of onset and also at the time of the worst oxygenation. Keeping the inspiratory pressures low (30-35 cm H2O [2.94 to 3.43 kPa]) reduces the frequency of pneumothorax, and might lower the mortality. Most patients are young, and therefore the costs per saved year of life are low.

The effect of dobutamine infusion on splanchnic blood flow and oxygen transport in patients with acute pancreatitis

OBJECTIVES

To measure the blood flow distribution and oxygen transport in pancreatitis and to evaluate the regional effects of increased systemic blood flow.

DESIGN

Nonrandomized controlled trial.

SETTING

A general intensive care unit in a tertiary care center.

PATIENTS

10 patients with pancreatitis requiring mechanical ventilation were studied after fluid resuscitation, and for the response to dobutamine, the patients served as their own controls. For the baseline, 11 patients scheduled for elective abdominal surgery served as a control group.

INTERVENTIONS

Systemic and regional hemodynamics were measured after fluid resuscitation to predefined hemodynamic endpoints. In patients with pancreatitis, the measurement was repeated after cardiac output had been increased by at least 25% by dobutamine.

MEASUREMENTS AND RESULTS

Hepatosplanchnic blood flow was estimated using regional catheterization and the dye dilution method. In patients with pancreatitis, the cardiac index did not differ from that of the control group (3.9 +/- 0.8 vs 4.1 +/- 0.71.min-1.m-2;NS). Accordingly, there was no difference in the splanchnic blood flow (1.1 +/- 0.4 vs 1.2 +/- 0.51.min-1.m-2;NS). Systemic and splanchnic oxygen consumption was increased in patients with pancreatitis (179 +/- 25 vs 147 +/- 27 ml.min-1.m-2, p < 0.05 and 68 +/- 15 vs 49 +/- 19 ml.min-1.m-2, p < 0.05), and systemic and splanchnic oxygen extraction was higher (0.34 +/- 0.08 vs 23 +/- 0.05, p < 0.01 and 0.46 +/- 0.18 vs 0.28 +/- 0.08, p < 0.05, respectively). Dobutamine had inconsistent effects on splanchnic blood flow: in individual patients, splanchnic blood flow even decreased substantially.

CONCLUSIONS

In severe pancreatitis, oxygen consumption is increased in the splanchnic region; increased splanchnic oxygen demand is not always met by adequately increased blood flow. Increasing the systemic blood flow with dobutamine does not improve perfusion in the splanchnic bed.

Lactate metabolism and regional lactate exchange after cardiac surgery

Tissue perfusion is at risk during cardiac surgery and in the immediate postoperative period. The association of low blood flow with metabolic acidosis and accumulation of lactate perioperatively has been well established. With the improvements in cardiopulmonary bypass and overall hemodynamic management, severe peri- and postoperative hypoperfusion has become rare. Despite the rarity of severe postoperative complications, several lines of evidence suggest that episodes of less severe hypoperfusion and borderline tissue oxygenation are relatively common, although generally well tolerated. Measurement of blood lactate levels is widely used to assess the adequacy of tissue perfusion. The interpretation of elevated blood lactate levels is limited by several confounding variables. Acute changes in acid-base balance, interorgan substrate flux, peripheral and visceral tissue perfusion, and hepatic lactate uptake will all influence blood lactate levels and may occur during and after cardiac surgery. Peri- and postoperative hyperlactatemia are rare occurrences and their presence may indicate inadequate tissue perfusion. Based on regional blood flow and lactate exchange measurements, we suggest that hyperlactatemia after cardiac surgery is a sign of inadequate or marginal tissue perfusion of the hepatosplanchnic region, as well as other tissues. In this article we briefly review: a) the normal physiology of lactate metabolism and the various causes of hyperlactatemia; b) studies on lactate levels during and after cardiac surgery; c) the evidence of insufficient or marginal tissue perfusion peri- and postoperatively; and d) the pathophysiology of postoperative increases in blood lactate based on regional lactate kinetics.

Splanchnic oxygen transport after cardiac surgery: evidence for inadequate tissue perfusion after stabilization of hemodynamics

OBJECTIVE

To evaluate the adequacy of visceral oxygen transport and gastric pHi after open heart surgery in patients with stable hemodynamics.

DESIGN

Nonrandomized control trial.

SETTING

A general intensive care unit in a tertiary care center.

PATIENTS

Sixteen postoperative cardiac surgery patients were studied after stabilization of systemic hemodynamics.

INTERVENTIONS

The effect of dobutamine infusion (6 mu g kg-1 min-1) on systemic and regional oxygen transport was studied in ten patients, with six patients serving as controls. Systemic oxygen consumption was measured by indirect calorimetry and splanchnic and femoral blood flow, by continuous infusion of indocyanine green using regional catheters and gastric mucosal pHi by gastric tonometer.

MEASUREMENTS AND RESULTS

Gastric mucosal acidosis was observed in half of the patients. Dobutamine increased cardiac output (3.2 +/- 0.6 vs 4.4 +/- 0.7 l x min-1 x min-2; P <0.05), splanchnic blood flow (0.68 +/- 0.28 vs 0.91 +/- 0.28 l x min-1 x m-2; p <0.05) and femoral blood flow (0.25 +/- 0.08 vs 0.32 +/- 0.11 l x min-1 x m-2; p <0.05). Changes in splanchnic oxygen delivery and consumption were parallel in the two study groups. In response to dobutamine, gastric pHi did not change (7.30 +/- 0.08 vs 7.31 +/- 0.06; NS), while in the control group, gastric pHi tended to decrease (7.32 +/- 0.04 vs 7.28 +/- 0.06; NS). Systemic oxygen consumption increased in response to dobutamine (141 +/- 11 vs 149 +/- 11 ml x min-1 x m-2; P <0.05) but did not change in the control group.

CONCLUSIONS

We conclude that a mismatch between splanchnic oxygen delivery and demand may be present despite stabilization of systemic hemodynamics after cardiac surgery. This is suggested by the parallel changes in splanchnic oxygen delivery and consumption. Dobutamine is likely to improve splanchnic tissue perfusion at this phase.

Estimation of splanchnic blood flow by the Fick principle in man and problems in the use of indocyanine green

OBJECTIVES

Measurement of splanchnic blood flow is necessary to evaluate the effect of therapeutic interventions on splanchnic tissue perfusion. Systemic indocyanine green (ICG) clearance has been used to estimate splanchnic blood flow, but the results may be compromised by altered hepatic dye extraction. We evaluated the applicability of simultaneous estimation of splanchnic and femoral blood flow by dye dilution and regional blood sampling in intensive care patients.

METHODS

240 simultaneous determinations of regional blood flow were conducted in different patient groups (cardiac surgery, ARDS, pancreatitis, septic shock, preoperative controls). The measurement protocol consists of catheterizations of hepatic vein, femoral artery and vein and primed constant infusion of two different ICG preparations.

RESULTS

The method was used successfully in a wide variety of patients. Steady-state dye concentration and sufficient dye extraction was achieved in each group of patients. The coefficient of variation of splanchnic blood flow estimation was 7 +/- 1% and of femoral blood flow estimation 6 +/- 0%. There was a great intra- and interindividual variation of ICG extraction. Use of dobutamine modified the extraction in most patients but did not lessen the performance of the method. ICG extraction was markedly lower and the coefficient of variation of both femoral and splanchnic blood flow markedly higher with propylene glycol-dissolved ICG preparation as compared with the freeze-dried.

CONCLUSIONS

The prerequisites for the method of primed, constant infusion of indocyanine green with hepatic vein catheterization are achieved in intensive care patients. The results of splanchnic blood flow estimations based on techniques with peripheral blood sampling should be interpreted with caution, and the use of ICG clearance as a flow-related indicator without the measurement of ICG extraction cannot be justified because of the great variability of dye extraction. Certain indocyanine green preparations may greatly modify the results of the regional blood flow determinations.

Metabolic stress modifies the thermogenic effect of dobutamine in man

OBJECTIVE

To study if metabolic stress modifies the thermogenic effect of dobutamine.

DESIGN

Prospective, increasing dose, pharmacologic study.

SETTING

Laboratory of the Department of Intensive Care Unit at a university hospital.

SUBJECTS

Twelve normal volunteers.

INTERVENTIONS

Dobutamine hydrochloride was infused to 12 healthy male volunteers starting at a dose of 2 micrograms/min/kg and gradually increased to 4 and 6 micrograms/min/kg. Each dose of dobutamine was infused for 20 mins. Metabolic stress was induced in six of the 12 volunteers using a triple hormone infusion (epinephrine, cortisol, and glucagon) before dobutamine, and was continued at a constant rate during the dobutamine infusion. The remaining six volunteers served as the control group and received only dobutamine.

MEASUREMENTS AND MAIN RESULTS

Oxygen consumption (VO2) was measured using a metabolic monitor. Arterial blood pressure was measured noninvasively, and cardiac output was monitored by Doppler echocardiography. Plasma concentrations of dopamine, norepinephrine, and epinephrine were measured in both groups. In the triple hormone group, blood was sampled to measure concentrations of insulin, glucagon, cortisol, free fatty acids, and glycerol to ensure the presence of a metabolic stress reaction. At the maximum dose, dobutamine induced a 19% increase (from 140 +/- 17 to 166 +/- 17 mL/min/m2) in VO2 in the control group and an 11% increase (from 167 +/- 10 to 184 +/- 13 mL/min/m2) in the triple hormone group (p < .05 between the two groups) compared with baseline. No change in the respiratory exchange ratio was seen. The triple hormone infusion alone induced hypermetabolism, a marked hemodynamic response, and increased lipolysis.

CONCLUSIONS

Stress, induced by a triple hormone infusion, diminishes the thermogenic effect of dobutamine. In the clinical setting, a > 10% to 15% increase in VO2 in response to dobutamine may not be explained just by the thermogenic effect of the drug.

Gastric mucosal pH does not reflect changes in splanchnic blood flow after cardiac surgery

Despite the widespread use of gastric tonometry to assess splanchnic oxygen transport, no human data are available on the relationship between splanchnic blood flow, splanchnic oxygen delivery and gastric mucosal pH. We have studied the effect of splanchnic blood flow and oxygen delivery on gastric mucosal pHi after cardiac surgery. During the first postoperative hours of intensive care, dopexamine was infused to increase cardiac output in eight patients, while six patients served as controls. Gastric mucosal pH (gastric tonometry), splanchnic blood flow and splanchnic oxygen delivery and consumption (dye dilution) were measured. Dopexamine administration significantly increased splanchnic blood flow (0.72 vs 1.02 litre min-1 m-2) (P < 0.05) and oxygen delivery (117 vs 161 ml min-1 m-2) (P < 0.05) compared with baseline values. However, splanchnic oxygen consumption remained unchanged and gastric mucosal pH levels decreased (7.30 vs 7.25) (P < 0.05). The proportion of splanchnic blood flow of cardiac output did not change in response to infusion of dopexamine, that is dopexamine did not favour blood flow distribution to the splanchnic region. In the control group there were no changes in splanchnic blood flow and oxygen delivery, while splanchnic oxygen consumption increased (36 vs 39 ml min-1 m-2) (P < 0.05) and gastric mucosal pH tended to decrease (7.33 vs 7.29) (ns). We conclude that after cardiac surgery gastric mucosal pH did not reflect changes in splanchnic blood flow and oxygen delivery suggesting heterogeneous or inadequate blood flow distribution within the splanchnic region.

Effect of vasoactive treatment on the relationship between mixed venous and regional oxygen saturation

OBJECTIVE

To evaluate the relationship between the mixed venous (SvO2), hepatic, and femoral venous oxygen saturations before and during sympathomimetic drug infusions.

DESIGN

Case series.

SETTING

Tertiary care center.

PATIENTS

Twenty-four ICU patients: postoperative open-heart surgery patients (n = 12), patients with septic shock (n = 8), and patients with acute respiratory failure (n = 4).

INTERVENTIONS

In postoperative open-heart surgery patients and patients with respiratory failure, cardiac output was increased by at least 25% following therapy with either dobutamine or dopamine. Patients with septic shock were treated with either dopamine or norepinephrine to correct hypotension.

MEASUREMENTS AND MAIN RESULTS

Vasoactive drug infusions increased cardiac index and oxygen delivery by 34% and oxygen consumption by 8%. SvO2 increased (62.6 +/- 6.7% vs. 69.5 +/- 6.0%, p less than .001). Although cardiac index was the most important determinant of SvO2, the correlation between cardiac index and SvO2 was weak (r2 = .32). The hepatic and femoral venous saturations also increased (49.0 +/- 12.1% vs. 59.4 +/- 9.8%, p less than .01, and 51.9 +/- 16.6% vs. 63.4 +/- 9.8%, p less than .001, respectively) in response to vasoactive treatment. The mean gradient between SvO2 and hepatic venous saturation was 11.9 +/- 8.7% and was independent of the clinical condition and baseline SvO2. The hepatic venous oxygen saturation increased in parallel with SvO2 regardless of the initial SvO2 value.

CONCLUSIONS

The individual values of SvO2 have no predictive value concerning regional oxygen transport. The parallel increase in SvO2 and hepatic venous oxygen saturation suggests that the vasoactive treatment did not compromise splanchnic oxygenation.