Category Archives: Acute Med

Acute care of the medically sick adult

Acute Med, All Updates, ICU, PHARM, Resus

Family presence during resuscitation

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CPR-iconFamilies allowed to be present during attempted cardiopulmonary resuscitation had improved psychological outcomes at ninety days.
Adult family members of adult patients were studied in this randomized study from France.
Resuscitation team member stress levels and effectiveness of resuscitation did not appear to be affected by family presence.
Family Presence during Cardiopulmonary Resuscitation
N Engl J Med. 2013 Mar 14;368(11):1008-18
[EXPAND Abstract]


BACKGROUND: The effect of family presence during cardiopulmonary resuscitation (CPR) on the family members themselves and the medical team remains controversial.

METHODS: We enrolled 570 relatives of patients who were in cardiac arrest and were given CPR by 15 prehospital emergency medical service units. The units were randomly assigned either to systematically offer the family member the opportunity to observe CPR (intervention group) or to follow standard practice regarding family presence (control group). The primary end point was the proportion of relatives with post-traumatic stress disorder (PTSD)-related symptoms on day 90. Secondary end points included the presence of anxiety and depression symptoms and the effect of family presence on medical efforts at resuscitation, the well-being of the health care team, and the occurrence of medicolegal claims.

RESULTS: In the intervention group, 211 of 266 relatives (79%) witnessed CPR, as compared with 131 of 304 relatives (43%) in the control group. In the intention-to-treat analysis, the frequency of PTSD-related symptoms was significantly higher in the control group than in the intervention group (adjusted odds ratio, 1.7; 95% confidence interval [CI], 1.2 to 2.5; P=0.004) and among family members who did not witness CPR than among those who did (adjusted odds ratio, 1.6; 95% CI, 1.1 to 2.5; P=0.02). Relatives who did not witness CPR had symptoms of anxiety and depression more frequently than those who did witness CPR. Family-witnessed CPR did not affect resuscitation characteristics, patient survival, or the level of emotional stress in the medical team and did not result in medicolegal claims.

CONCLUSIONS: Family presence during CPR was associated with positive results on psychological variables and did not interfere with medical efforts, increase stress in the health care team, or result in medicolegal conflicts.

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Acute Med, All Updates, ICU, Resus

Age adjusted D-dimer cut-off values

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Age adjusted D-dimer cut-off values (age×10 µg/L) improve specificity without losing sensitivity for venous thromboembolism. This could spare many elderly patients unnecessary imaging. Full text is available free from the BMJ.
Diagnostic accuracy of conventional or age adjusted D-dimer cut-off values in older patients with suspected venous thromboembolism: systematic review and meta-analysis>
BMJ. 2013 May 3;346:f2492
[EXPAND Abstract]


OBJECTIVE: To review the diagnostic accuracy of D-dimer testing in older patients (>50 years) with suspected venous thromboembolism, using conventional or age adjusted D-dimer cut-off values.

DESIGN Systematic review and bivariate random effects meta-analysis.

DATA SOURCES: We searched Medline and Embase for studies published before 21 June 2012 and we contacted the authors of primary studies.

STUDY SELECTION: Primary studies that enrolled older patients with suspected venous thromboembolism in whom D-dimer testing, using both conventional (500 µg/L) and age adjusted (age × 10 µg/L) cut-off values, and reference testing were performed. For patients with a non-high clinical probability, 2 × 2 tables were reconstructed and stratified by age category and applied D-dimer cut-off level.

RESULTS: 13 cohorts including 12,497 patients with a non-high clinical probability were included in the meta-analysis. The specificity of the conventional cut-off value decreased with increasing age, from 57.6% (95% confidence interval 51.4% to 63.6%) in patients aged 51-60 years to 39.4% (33.5% to 45.6%) in those aged 61-70, 24.5% (20.0% to 29.7% in those aged 71-80, and 14.7% (11.3% to 18.6%) in those aged >80. Age adjusted cut-off values revealed higher specificities over all age categories: 62.3% (56.2% to 68.0%), 49.5% (43.2% to 55.8%), 44.2% (38.0% to 50.5%), and 35.2% (29.4% to 41.5%), respectively. Sensitivities of the age adjusted cut-off remained above 97% in all age categories.

CONCLUSIONS: The application of age adjusted cut-off values for D-dimer tests substantially increases specificity without modifying sensitivity, thereby improving the clinical utility of D-dimer testing in patients aged 50 or more with a non-high clinical probability.

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Acute Med, All Updates, ICU, Resus

Restricting transfusion in upper GI bleeding

Improved outcomes and reduced complications were associated with a restrictive transfusion strategy in patients with upper gastrointestinal bleeding. Note that patients with “massive exsanguinating bleeding” were excluded from the study so this shouldn’t be extrapolated to such presentations.
The benefit seemed to be most marked in patients with variceal haemorrhage, but not those with the most severe Child-Pugh class. In portal hypertensive-related bleeding, transfusion may increase portal pressure and exacerbate bleeding.
The patients were ‘scoped within 6 hours, and less than 10% received FFP or platelets. Both groups averaged over 5 litres of crystalloid in the first 72 hours.
Transfusion Strategies for Acute Upper Gastrointestinal Bleeding
N Engl J Med. 2013 Jan 3;368(1):11-21
[EXPAND Abstract]


BACKGROUND: The hemoglobin threshold for transfusion of red cells in patients with acute gastrointestinal bleeding is controversial. We compared the efficacy and safety of a restrictive transfusion strategy with those of a liberal transfusion strategy.

METHODS: We enrolled 921 patients with severe acute upper gastrointestinal bleeding and randomly assigned 461 of them to a restrictive strategy (transfusion when the hemoglobin level fell below 7 g per deciliter) and 460 to a liberal strategy (transfusion when the hemoglobin fell below 9 g per deciliter). Randomization was stratified according to the presence or absence of liver cirrhosis.

RESULTS: A total of 225 patients assigned to the restrictive strategy (51%), as compared with 61 assigned to the liberal strategy (14%), did not receive transfusions (P<0.001) [corrected].The probability of survival at 6 weeks was higher in the restrictive-strategy group than in the liberal-strategy group (95% vs. 91%; hazard ratio for death with restrictive strategy, 0.55; 95% confidence interval [CI], 0.33 to 0.92; P=0.02). Further bleeding occurred in 10% of the patients in the restrictive-strategy group as compared with 16% of the patients in the liberal-strategy group (P=0.01), and adverse events occurred in 40% as compared with 48% (P=0.02). The probability of survival was slightly higher with the restrictive strategy than with the liberal strategy in the subgroup of patients who had bleeding associated with a peptic ulcer (hazard ratio, 0.70; 95% CI, 0.26 to 1.25) and was significantly higher in the subgroup of patients with cirrhosis and Child-Pugh class A or B disease (hazard ratio, 0.30; 95% CI, 0.11 to 0.85), but not in those with cirrhosis and Child-Pugh class C disease (hazard ratio, 1.04; 95% CI, 0.45 to 2.37). Within the first 5 days, the portal-pressure gradient increased significantly in patients assigned to the liberal strategy (P=0.03) but not in those assigned to the restrictive strategy.

CONCLUSIONS: As compared with a liberal transfusion strategy, a restrictive strategy significantly improved outcomes in patients with acute upper gastrointestinal bleeding. (Funded by Fundació Investigació Sant Pau; ClinicalTrials.gov number, NCT00414713.).

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Acute Med, All Updates, Resus

Pleurodesis for spontaneous pneumothorax?

A Taiwanese study demonstrated a lower recurrence rate when primary spontaneous pneumothoraces requiring drainage received pleurodesis using minocycline(1). However, significantly more pleurodesed patients required opioid analgesia, and the success rates were less than are found with surgical methods, which are recommended in the West, where pleurodesis is reserved for patients unfit for surgery(2).
1. Simple aspiration and drainage and intrapleural minocycline pleurodesis versus simple aspiration and drainage for the initial treatment of primary spontaneous pneumothorax: an open-label, parallel-group, prospective, randomised, controlled trial
Lancet. 2013 Apr 13;381(9874):1277-82
[EXPAND Abstract]


BACKGROUND: Simple aspiration and drainage is a standard initial treatment for primary spontaneous pneumothorax, but the rate of pneumothorax recurrence is substantial. We investigated whether additional minocycline pleurodesis after simple aspiration and drainage reduces the rate of recurrence.

METHODS: In our open-label, parallel-group, prospective, randomised, controlled trial at two hospitals in Taiwan, patients were aged 15-40 years and had a first episode of primary spontaneous pneumothorax with a rim of air greater than 2 cm on chest radiographs, complete lung expansion without air leakage after pigtail catheter drainage, adequate haematological function, and normal renal and hepatic function. After simple aspiration and drainage via a pigtail catheter, patients were randomly assigned (1:1) to receive 300 mg of minocycline pleurodesis or no further treatment (control group). Randomisation was by computer-generated random numbers in sealed envelopes. Our primary endpoint was rate of pneumothorax recurrence at 1 year. This trial is registered with ClinicalTrials.gov (NCT00418392).

FINDINGS: Between Dec 31, 2006, and June 30, 2012, 214 patients were randomly assigned-106 to the minocycline group and 108 to the control group (intention-to-treat population). Treatment was unsuccessful within 7 days of randomisation in 14 patients in the minocycline group and 20 patients in the control group. At 1 year, pneumothoraces had recurred in 31 of 106 (29·2%) patients in the minocycline group compared with 53 of 108 (49·1%) in the control group (p=0·003). We noted no procedure-related complications in either group.

INTERPRETATION: Simple aspiration and drainage followed by minocycline pleurodesis is a safe and more effective treatment for primary spontaneous pneumothorax than is simple aspiration and drainage only. Minocycline pleurodesis should be an adjunct to standard treatment for primary spontaneous pneumothorax.

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2. Primary spontaneous pneumothorax: to pleurodese or not?
Lancet. 2013 Apr 13;381(9874):1252-4

Acute Med, All Updates, PHARM, Resus

Isolated LAFB and outcome

A small study followed up an older cohort of patients with isolated left anterior fascicular block on their ECG (isolated left axis deviation), without clinically manifest cardiovascular disease.

LAFB-litfl
Learn about LAFB at Life In The Fast Lane

LAFB was associated with an increased risk of atrial fibrillation, heart failure and death. LAFB is caused by conduction tissue fibrosis, and is a marker of other left heart fibrosis. The patients did not go on to develop left bundle branch block, and only 2 of 39 required pacing in 10 years, suggesting these outcomes were not due to progression of conduction disease.

Long-term Outcomes of Left Anterior Fascicular Block in the Absence of Overt Cardiovascular Disease
JAMA. 2013 Apr 17;309(15):1587-8

Acute Med, All Updates, PHARM, Resus

5 days of steroids for COPD exacerbation

A randomised trial showed 5 days of oral steroid therapy (40 mg prednisone) was non-inferior to 14 days’ duration in delaying the next exacerbation.
Short-term vs conventional glucocorticoid therapy in acute exacerbations of chronic obstructive pulmonary disease: the REDUCE randomized clinical trial
JAMA. 2013 Jun 5;309(21):2223-31
[EXPAND Abstract]


IMPORTANCE: International guidelines advocate a 7- to 14-day course of systemic glucocorticoid therapy in acute exacerbations of chronic obstructive pulmonary disease (COPD). However, the optimal dose and duration are unknown.

OBJECTIVE: To investigate whether a short-term (5 days) systemic glucocorticoid treatment in patients with COPD exacerbation is noninferior to conventional (14 days) treatment in clinical outcome and whether it decreases the exposure to steroids.

DESIGN, SETTING, AND PATIENTS: REDUCE: (Reduction in the Use of Corticosteroids in Exacerbated COPD), a randomized, noninferiority multicenter trial in 5 Swiss teaching hospitals, enrolling 314 patients presenting to the emergency department with acute COPD exacerbation, past or present smokers (≥20 pack-years) without a history of asthma, from March 2006 through February 2011.

INTERVENTIONS: Treatment with 40 mg of prednisone daily for either 5 or 14 days in a placebo-controlled, double-blind fashion. The predefined noninferiority criterion was an absolute increase in exacerbations of at most 15%, translating to a critical hazard ratio of 1.515 for a reference event rate of 50%.

MAIN OUTCOME AND MEASURE: Time to next exacerbation within 180 days.

RESULTS: Of 314 randomized patients, 289 (92%) of whom were admitted to the hospital, 311 were included in the intention-to-treat analysis and 296 in the per-protocol analysis. Hazard ratios for the short-term vs conventional treatment group were 0.95 (90% CI, 0.70 to 1.29; P = .006 for noninferiority) in the intention-to-treat analysis and 0.93 (90% CI, 0.68 to 1.26; P = .005 for noninferiority) in the per-protocol analysis, meeting our noninferiority criterion. In the short-term group, 56 patients (35.9%) reached the primary end point; 57 (36.8%) in the conventional group. Estimates of reexacerbation rates within 180 days were 37.2% (95% CI, 29.5% to 44.9%) in the short-term; 38.4% (95% CI, 30.6% to 46.3%) in the conventional, with a difference of -1.2% (95% CI, -12.2% to 9.8%) between the short-term and the conventional. Among patients with a reexacerbation, the median time to event was 43.5 days (interquartile range [IQR], 13 to 118) in the short-term and 29 days (IQR, 16 to 85) in the conventional. There was no difference between groups in time to death, the combined end point of exacerbation, death, or both and recovery of lung function. In the conventional group, mean cumulative prednisone dose was significantly higher (793 mg [95% CI, 710 to 876 mg] vs 379 mg [95% CI, 311 to 446 mg], P < .001), but treatment-associated adverse reactions, including hyperglycemia and hypertension, did not occur more frequently.
CONCLUSIONS AND RELEVANCE: In patients presenting to the emergency department with acute exacerbations of COPD, 5-day treatment with systemic glucocorticoids was noninferior to 14-day treatment with regard to reexacerbation within 6 months of follow-up but significantly reduced glucocorticoid exposure. These findings support the use of a 5-day glucocorticoid treatment in acute exacerbations of COPD.

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Acute Med, All Updates, ICU, Resus

Potential new therapy for acute heart failure

Interesting new drug to know about: Serelaxin, recombinant human relaxin-2. It’s hard to assess the clinical significance of the statistically significant findings. Let’s see if a benefit is replicated in future studies. It’s hard to imagine a normotensive patient that can’t be fixed with existing therapies though.
Serelaxin, recombinant human relaxin-2, for treatment of acute heart failure (RELAX-AHF): a randomised, placebo-controlled trial.
Lancet. 2013 Jan 5;381(9860):29-39
[EXPAND Abstract]


BACKGROUND: Serelaxin, recombinant human relaxin-2, is a vasoactive peptide hormone with many biological and haemodynamic effects. In a pilot study, serelaxin was safe and well tolerated with positive clinical outcome signals in patients with acute heart failure. The RELAX-AHF trial tested the hypothesis that serelaxin-treated patients would have greater dyspnoea relief compared with patients treated with standard care and placebo.

METHODS: RELAX-AHF was an international, double-blind, placebo-controlled trial, enrolling patients admitted to hospital for acute heart failure who were randomly assigned (1:1) via a central randomisation scheme blocked by study centre to standard care plus 48-h intravenous infusions of placebo or serelaxin (30 μg/kg per day) within 16 h from presentation. All patients had dyspnoea, congestion on chest radiograph, increased brain natriuretic peptide (BNP) or N-terminal prohormone of BNP, mild-to-moderate renal insufficiency, and systolic blood pressure greater than 125 mm Hg. Patients, personnel administering study drug, and those undertaking study-related assessments were masked to treatment assignment. The primary endpoints evaluating dyspnoea improvement were change from baseline in the visual analogue scale area under the curve (VAS AUC) to day 5 and the proportion of patients with moderate or marked dyspnoea improvement measured by Likert scale during the first 24 h, both analysed by intention to treat. This trial is registered at ClinicalTrials.gov, NCT00520806.

FINDINGS: 1161 patients were randomly assigned to serelaxin (n=581) or placebo (n=580). Serelaxin improved the VAS AUC primary dyspnoea endpoint (448 mm × h, 95% CI 120-775; p=0·007) compared with placebo, but had no significant effect on the other primary endpoint (Likert scale; placebo, 150 patients [26%]; serelaxin, 156 [27%]; p=0·70). No significant effects were recorded for the secondary endpoints of cardiovascular death or readmission to hospital for heart failure or renal failure (placebo, 75 events [60-day Kaplan-Meier estimate, 13·0%]; serelaxin, 76 events [13·2%]; hazard ratio [HR] 1·02 [0·74-1·41], p=0·89] or days alive out of the hospital up to day 60 (placebo, 47·7 [SD 12·1] days; serelaxin, 48·3 [11·6]; p=0·37). Serelaxin treatment was associated with significant reductions of other prespecified additional endpoints, including fewer deaths at day 180 (placebo, 65 deaths; serelaxin, 42; HR 0·63, 95% CI 0·42-0·93; p=0·019).

INTERPRETATION: Treatment of acute heart failure with serelaxin was associated with dyspnoea relief and improvement in other clinical outcomes, but had no effect on readmission to hospital. Serelaxin treatment was well tolerated and safe, supported by the reduced 180-day mortality

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Acute Med, All Updates, PHARM, Resus

Stroke thrombolysis outcomes from registry

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Data from a large national stroke registry are reported to show that in patients who received tPA, outcomes were worse the later it was given. From a registry of over a million patients, the study group included 58353 patients from 1395 sites treated after emergency department arrival with IV tPA within 4.5 hours of symptom onset. Reported odds ratios were small but statistically significant in this large sample size. There was a 4.9% rate of intracranial haemorrhage.
As there is no comparison with patients who did not receive tPA, one cannot conclude from this study that tPA is either beneficial or harmful. It may however be used as an argument that if you’re working in a centre where the patients are going to get the tPA, it’s advisable not to delay it.
Time to treatment with intravenous tissue plasminogen activator and outcome from acute ischemic stroke
JAMA. 2013 Jun 19;309(23):2480-8
[EXPAND Abstract]


IMPORTANCE: Randomized clinical trials suggest the benefit of intravenous tissue-type plasminogen activator (tPA) in acute ischemic stroke is time dependent. However, modest sample sizes have limited characterization of the extent to which onset to treatment (OTT) time influences outcome; and the generalizability of findings to clinical practice is uncertain.

OBJECTIVE: To evaluate the degree to which OTT time is associated with outcome among patients with acute ischemic stroke treated with intraveneous tPA.

DESIGN, SETTING, AND PATIENTS: Data were analyzed from 58,353 patients with acute ischemic stroke treated with tPA within 4.5 hours of symptom onset in 1395 hospitals participating in the Get With The Guidelines-Stroke Program, April 2003 to March 2012.

MAIN OUTCOMES AND MEASURES: Relationship between OTT time and in-hospital mortality, symptomatic intracranial hemorrhage, ambulatory status at discharge, and discharge destination.

RESULTS: Among the 58,353 tPA-treated patients, median age was 72 years, 50.3% were women, median OTT time was 144 minutes (interquartile range, 115-170), 9.3% (5404) had OTT time of 0 to 90 minutes, 77.2% (45,029) had OTT time of 91 to 180 minutes, and 13.6% (7920) had OTT time of 181 to 270 minutes. Median pretreatment National Institutes of Health Stroke Scale documented in 87.7% of patients was 11 (interquartile range, 6-17). Patient factors most strongly associated with shorter OTT included greater stroke severity (odds ratio [OR], 2.8; 95% CI, 2.5-3.1 per 5-point increase), arrival by ambulance (OR, 5.9; 95% CI, 4.5-7.3), and arrival during regular hours (OR, 4.6; 95% CI, 3.8-5.4). Overall, there were 5142 (8.8%) in-hospital deaths, 2873 (4.9%) patients had intracranial hemorrhage, 19,491 (33.4%) patients achieved independent ambulation at hospital discharge, and 22,541 (38.6%) patients were discharged to home. Faster OTT, in 15-minute increments, was associated with reduced in-hospital mortality (OR, 0.96; 95% CI, 0.95-0.98; P < .001), reduced symptomatic intracranial hemorrhage (OR, 0.96; 95% CI, 0.95-0.98; P < .001), increased achievement of independent ambulation at discharge (OR, 1.04; 95% CI, 1.03-1.05; P < .001), and increased discharge to home (OR, 1.03; 95% CI, 1.02-1.04; P < .001).
CONCLUSIONS AND RELEVANCE: In a registry representing US clinical practice, earlier thrombolytic treatment was associated with reduced mortality and symptomatic intracranial hemorrhage, and higher rates of independent ambulation at discharge and discharge to home following acute ischemic stroke. These findings support intensive efforts to accelerate hospital presentation and thrombolytic treatment in patients with stroke.

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Acute Med, All Updates, ICU

TracMan results

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The TracMan trial – a multicentre randomised trial of early vs late tracheostomy in ICU patients – has been published, showing no difference in the primary outcome of mortality.
A review of the trial is posted on the excellent PulmCCM blog:

There was no proven difference between groups in 30-day mortality (30.8% early vs. 31.5% late, primary outcome), nor in any other outcome including 2-year mortality.

Patients getting early tracheostomies required fewer days of sedation, and there was a suggestion of a reduction of -1.7 ventilator days with early trach (mean 13.6 days vs 15.2 days, p=0.06). However, ICU stays were exactly equal at a median 13 days.

Also, 7% of patients had significant bleeding attributed to their tracheostomies (defined as needing IV fluids or another intervention); this amounted to 11 patients in the early group and 8 in the late group.

PulmCCM is an excellent free resource that will deliver critical care updates to your inbox. It has a number of other useful features, like free board review questions – highly recommended!
Effect of early vs late tracheostomy placement on survival in patients receiving mechanical ventilation: the TracMan randomized trial
JAMA. 2013 May 22;309(20):2121-9
[EXPAND Abstract]


IMPORTANCE: Tracheostomy is a widely used intervention in adult critical care units. There is little evidence to guide clinicians regarding the optimal timing for this procedure.

OBJECTIVE: To test whether early vs late tracheostomy would be associated with lower mortality in adult patients requiring mechanical ventilation in critical care units.

DESIGN AND SETTING: An open multicentered randomized clinical trial conducted between 2004 and 2011 involving 70 adult general and 2 cardiothoracic critical care units in 13 university and 59 nonuniversity hospitals in the United Kingdom.

PARTICIPANTS: Of 1032 eligible patients, 909 adult patients breathing with the aid of mechanical ventilation for less than 4 days and identified by the treating physician as likely to require at least 7 more days of mechanical ventilation.

INTERVENTIONS: Patients were randomized 1:1 to early tracheostomy (within 4 days) or late tracheostomy (after 10 days if still indicated).

MAIN OUTCOMES AND MEASURES: The primary outcome measure was 30-day mortality and the analysis was by intention to treat.

RESULTS: Of the 455 patients assigned to early tracheostomy, 91.9% (95% CI, 89.0%-94.1%) received a tracheostomy and of 454 assigned to late tracheostomy, 44.9% (95% CI, 40.4%-49.5%) received a tracheostomy. All-cause mortality 30 days after randomization was 30.8% (95% CI, 26.7%-35.2%) in the early and 31.5% (95% CI, 27.3%-35.9%) in the late group (absolute risk reduction for early vs late, 0.7%; 95% CI, -5.4% to 6.7%). Two-year mortality was 51.0% (95% CI, 46.4%-55.6%) in the early and 53.7% (95% CI, 49.1%-58.3%) in the late group (P = .74). Median critical care unit length of stay in survivors was 13.0 days in the early and 13.1 days in the late group (P = .74). Tracheostomy-related complications were reported for 6.3% (95% CI, 4.6%-8.5%) of patients (5.5% in the early group, 7.8% in the late group).

CONCLUSIONS AND RELEVANCE: For patients breathing with the aid of mechanical ventilation treated in adult critical care units in the United Kingdom, tracheostomy within 4 days of critical care admission was not associated with an improvement in 30-day mortality or other important secondary outcomes. The ability of clinicians to predict which patients required extended ventilatory support was limited.

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Acute Med, All Updates, ICU, Resus, Ultrasound

Predicting volume responsiveness

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IVCiconOne of the current Holy Grails of ED critical care is to find a reliable measure of fluid responsiveness in those patients with impaired organ perfusion, such as those with severe sepsis. This would enable us to identify those patients whose cardiac output would be improved by fluid therapy, and avoid subjecting ‘non-responders’ to the risks associated with fluid overload. Thanks to the uptake of early goal-directed therapy in sepsis, under-resuscitation is now much less common in the ED. However a growing evidence base reveals the dangers of over-resuscitation. We have a responsibility to optimise fluid therapy as best we can with the equipment we have, according to the latest evidence.
Inferior Vena Cava Ultrasound
Some tests of fluid responsiveness rely on the effect of respiration-induced changes in pleural pressure on the circulation. Inferior vena cava (IVC) size and degree of inspiratory collapse correlate with central venous pressure (CVP), but CVP is not a reliable predictor of volume status or responsiveness. Skinny, collapsing IVCs detected on ultrasound suggest volume responsiveness, but the lack of this finding does not exclude fluid responsiveness. IVC size and measurement can be affected by patient position, probe position, and a variety of health states from athleticism to increased abdominal pressure.
Pulse Pressure Variation
Respiratory pulse pressure variation derived from an arterial line trace in mechanically ventilated patients who are adequately sedated and receiving large tidal volumes can predict fluid responsiveness too. Variability in tidal volume, the presence of spontaneous breathing activity in a ventilated patient, and cardiac dysrhythmia can all confound the usefulness of this method.
End expiratory occlusion
Another test in mechanically ventilated patients is the end expiratory occlusion test. A positive pressure inspiratory breath cyclically decreases the left cardiac preload. Occluding the circuit at end-expiration prevents this cyclic impediment in left cardiac preload and acts like a fluid challenge. A 15 second expiratory occlusion is performed and an increase in pulse pressure or (if you can measure it) cardiac index predicts fluid responsiveness with a high degree of accuracy. The patient must be able to tolerate the 15 second interruption to ventilation without initiating a spontaneous breath.
Passive Leg Raise
Passive leg raising (PLR) involves measuring cardiac output (or its surrogate, velocity-time integral, or VTI) before and after tilting the semirecumbent patient supine and raising the legs to 45 degrees. This ‘autotransfuses’ blood from the lower limbs to the core and acts as a reversible fluid challenge. An increase in VTI identifies fluid responders. It would be nice if a PLR-induced increase in blood pressure revealed the answer, but BP does not reliably inform us of changes in cardiac output.
All these tests have limitations. Pulse pressure variation fails in patients with low respiratory system compliance, such as is found in ARDS(1). End-expiratory occlusion and PLR work in low respiratory system compliance, but the former still requires mechanical ventilation, and the latter requires a means of estimating cardiac output or a surrogate – oesophageal Doppler, the velocity-time integral measured by transthoracic echocardiography, and femoral artery flow (measured by arterial Doppler) have all been used. Non-invasive cardiac output monitors that are not operator dependent exist, such as the NICOM(TM) bioreactance device. Bioreactance cardiac output measurement is based on an analysis of relative phase shifts of an oscillating current that occurs when this current traverses the thoracic cavity. Its advantages are that it is noninvasive, it does not require endotracheal intubation or an arterial line, and it provides a good estimate of stroke volume in patients with atrial fibrillation.
A recent study evaluating the combination of PLR with NICOM(TM) bioreactance monitoring revealed that another tool could indicate volume responsiveness: an increase in carotid blood flow after PLR, as measured by carotid Doppler flow imaging(2). A threshold increase in carotid Doppler flow imaging of 20% for predicting volume responsiveness had a sensitivity and specificity of 94% and 86%, respectively. This was studied in a heterogenous group of hemodynamically unstable patients, suggesting applicability to the kind of patients who present to the ED, although numbers were small so more validation is required.
End-tidal carbon dioxide
End-tidal carbon dioxide (ETCO2) levels depend on cardiac output. Increasing cardiac output with a fluid challenge or PLR increases ETCO2,as long as ventilatory and metabolic conditions remain stable. In a recent small study, a PLR-induced increase in ETCO2 ≥ 5 % predicted a fluid-induced increase in cardiac index ≥ 15 % with sensitivity of 71 % (95 % confidence interval: 48-89 %) and specificity of 100 (82-100) %(3). The maximal effects of PLR on CI and ETCO2 were observed within 1 min.
So what can I use?
In summary, differentiating fluid responders from non-responders in the ED remains a challenge. The method used depends on available equipment and expertise, and whether the patient is spontaneously breathing or mechanically ventilated. The NICOM(TM) shows great promise but until your department can afford one, ultrasound is the way to go; small collapsing IVCs suggest fluid responders. Learning to measure a VTI on transthoracic echo or carotid Doppler flow will help you assess the response to a PLR in spontaneously ventilating patients. If they’re mechanically ventilated, then looking for an ETCO2 rise after PLR could be a simpler alternative.

Fluid responsiveness assessment – options in the Emergency Department

Inferior Vena Cava Ultrasound
Helpful if skinny / large degree of respirophasic collapse – suggests fluid responsive – ventilated or spontaneous breathing

Passive Leg Raise
Good in ventilated or spontaneous breathing patients; need to measure cardiac output or a surrogate, such as VTI (echo), NICOM(TM), carotid Doppler flow, or ETCO2 (if ventilation and metabolic status constant)

Pulse Pressure Variation
Requires full mechanical ventilation; no good if low respiratory compliance / disturbed heart-lung interaction

End expiratory occlusion
Requires mechanical ventilation and patient tolerance of 15 seconds of apnoea. Acts like a passive leg raise so need a measure of cardiac output or surrogate

 
I look forward to more studies on these modalities, and to trying some of them in the resus room at every available opportunity.
 
1. Passive leg-raising and end-expiratory occlusion tests perform better than pulse pressure variation in patients with low respiratory system compliance
Crit Care Med. 2012 Jan;40(1):152-7
[EXPAND Abstract]


OBJECTIVES: We tested whether the poor ability of pulse pressure variation to predict fluid responsiveness in cases of acute respiratory distress syndrome was related to low lung compliance. We also tested whether the changes in cardiac index induced by passive leg-raising and by an end-expiratory occlusion test were better than pulse pressure variation at predicting fluid responsiveness in acute respiratory distress syndrome patients.

DESIGN: Prospective study.

SETTING: Medical intensive care unit.

PATIENTS: We included 54 patients with circulatory shock (63 ± 13 yrs; Simplified Acute Physiology Score II, 63 ± 24). Twenty-seven patients had acute respiratory distress syndrome (compliance of the respiratory system, 22 ± 3 mL/cm H2O). In nonacute respiratory distress syndrome patients, the compliance of the respiratory system was 45 ± 9 mL/cm H2O.

MEASUREMENTS AND MAIN RESULTS: We measured the response of cardiac index (transpulmonary thermodilution) to fluid administration (500 mL saline). Before fluid administration, we recorded pulse pressure variation and the changes in pulse contour analysis-derived cardiac index induced by passive leg-raising and end-expiratory occlusion. Fluid increased cardiac index ≥ 15% (44% ± 39%) in 30 “responders.” Pulse pressure variation was significantly correlated with compliance of the respiratory system (r = .58), but not with tidal volume. The higher the compliance of the respiratory system, the better the prediction of fluid responsiveness by pulse pressure variation. A compliance of the respiratory system of 30 mL/cm H2O was the best cut-off for discriminating patients regarding the ability of pulse pressure variation to predict fluid responsiveness. If compliance of the respiratory system was >30 mL/cm H2O, then the area under the receiver-operating characteristics curve for predicting fluid responsiveness was not different for pulse pressure variation and the passive leg-raising and end-expiratory occlusion tests (0.98 ± 0.03, 0.91 ± 0.06, and 0.97 ± 0.03, respectively). By contrast, if compliance of the respiratory system was ≤ 30 mL/cm H2O, then the area under the receiver-operating characteristics curve was significantly lower for pulse pressure variation than for the passive leg-raising and end-expiratory occlusion tests (0.69 ± 0.10, 0.94 ± 0.05, and 0.93 ± 0.05, respectively).

CONCLUSIONS: The ability of pulse pressure variation to predict fluid responsiveness was inversely related to compliance of the respiratory system. If compliance of the respiratory system was ≤ 30 mL/cm H2O, then pulse pressure variation became less accurate for predicting fluid responsiveness. However, the passive leg-raising and end-expiratory occlusion tests remained valuable in such cases.

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2. The use of bioreactance and carotid doppler to determine volume responsiveness and blood flow redistribution following passive leg raising in hemodynamically unstable patients
Chest. 2013 Feb 1;143(2):364-70
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BACKGROUND: The clinical assessment of intravascular volume status and volume responsiveness is one of the most difficult tasks in critical care medicine. Furthermore, accumulating evidence suggests that both inadequate and overzealous fluid resuscitation are associated with poor outcomes. The objective of this study was to determine the predictive value of passive leg raising (PLR)- induced changes in stroke volume index (SVI) as assessed by bioreactance in predicting volume responsiveness in a heterogenous group of patients in the ICU. A secondary end point was to evaluate the change in carotid Doppler fl ow following the PLR maneuver.

METHODS: During an 8-month period, we collected clinical, hemodynamic, and carotid Doppler data on hemodynamically unstable patients in the ICU who underwent a PLR maneuver as part of our resuscitation protocol. A patient whose SVI increased by . 10% following a fluid challenge was considered a fluid responder.

RESULTS: A complete data set was available for 34 patients. Twenty-two patients (65%) had severe sepsis/septic shock, whereas 21 (62%) required vasopressor support and 19 (56%) required mechanical ventilation. Eighteen patients (53%) were volume responders. The PLR maneuver had a sensitivity of 94% and a specificity of 100% for predicting volume responsiveness (one false negative result). In the 19 patients undergoing mechanical ventilation, the stroke volume variation was 18.0% 5.1% in the responders and 14.8% 3.4% in the nonresponders ( P 5 .15). Carotid blood fl ow increased by 79% 32% after the PLR in the responders compared with 0.1% 14% in the nonresponders ( P , .0001). There was a strong correlation between the percent change in SVI by PLR and the concomitant percent change in carotid blood fl ow ( r 5 0.59, P 5 .0003). Using a threshold increase in carotid Doppler fl ow imaging of 20% for predicting volume responsiveness, there were two false positive results and one false negative result, giving a sensitivity and specificity of 94% and 86%, respectively. We noted a significant increase in the diameter of the common carotid artery in the fluid responders.

CONCLUSIONS: Monitoring the hemodynamic response to a PLR maneuver using bioreactance provides an accurate method of assessing volume responsiveness in critically ill patients. In addition, the study suggests that changes in carotid blood fl ow following a PLR maneuver may be a useful adjunctive method for determining fluid responsiveness in hemodynamically unstable patients.

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3. End-tidal carbon dioxide is better than arterial pressure for predicting volume responsiveness by the passive leg raising test
Intensive Care Med. 2013 Jan;39(1):93-100
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PURPOSE: In stable ventilatory and metabolic conditions, changes in end-tidal carbon dioxide (EtCO(2)) might reflect changes in cardiac index (CI). We tested whether EtCO(2) detects changes in CI induced by volume expansion and whether changes in EtCO(2) during passive leg raising (PLR) predict fluid responsiveness. We compared EtCO(2) and arterial pulse pressure for this purpose.

METHODS: We included 65 patients [Simplified Acute Physiology Score (SAPS) II = 57 ± 19, 37 males, under mechanical ventilation without spontaneous breathing, 15 % with chronic obstructive pulmonary disease, baseline CI = 2.9 ± 1.1 L/min/m(2)] in whom a fluid challenge was decided due to circulatory failure and who were monitored by an expiratory-CO(2) sensor and a PiCCO2 device. In all patients, we measured arterial pressure, EtCO(2), and CI before and after a fluid challenge. In 40 patients, PLR was performed before fluid administration. The PLR-induced changes in arterial pressure, EtCO(2), and CI were recorded.

RESULTS: Considering the whole population, the fluid-induced changes in EtCO(2) and CI were correlated (r (2) = 0.45, p = 0.0001). Considering the 40 patients in whom PLR was performed, volume expansion increased CI ≥ 15 % in 21 “volume responders.” A PLR-induced increase in EtCO(2) ≥ 5 % predicted a fluid-induced increase in CI ≥ 15 % with sensitivity of 71 % (95 % confidence interval: 48-89 %) and specificity of 100 (82-100) %. The prediction ability of the PLR-induced changes in CI was not different. The area under the receiver-operating characteristic (ROC) curve for the PLR-induced changes in pulse pressure was not significantly different from 0.5.

CONCLUSION: The changes in EtCO(2) induced by a PLR test predicted fluid responsiveness with reliability, while the changes in arterial pulse pressure did not.

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