Tag Archives: diagnosis

Lung ultrasound for pneumothorax by paramedics

This UK study showed that paramedics could successfully acquire and identify lung ultrasound images after a two day course. The course covered the identification and management of patients who present with serious thoracic injury, with a specific focus on the use of thoracic ultrasound during early prehospital assessment. Standard 2D images for pleural sliding and comet tails and M-Mode for the ‘seashore sign’ were acquired, and colour Doppler was also used to assist in the identification of pleural sliding.

Objective This trial investigated whether advanced paramedics from a UK regional ambulance service have the ability to acquire and interpret diagnostic quality ultrasound images following a 2-day programme of education and training covering the fundamental aspects of lung ultrasound.

Method The participants were tested using a two-part examination; assessing both their theoretical understanding of image interpretation and their practical ability to acquire diagnostic quality ultrasound images. The results obtained were subsequently compared with those obtained from expert physician sonographers.

Results The advanced paramedics demonstrated an overall accuracy in identifying the presence or absence of pneumothorax in M-mode clips of 0.94 (CI 0.86 to 0.99), compared with the experts who achieved 0.93 (CI 0.67 to 1.0). In two-dimensional mode, the advanced paramedics demonstrated an overall accuracy of 0.78 (CI 0.72 to 0.83), compared with the experts who achieved 0.76 (CI 0.62 to 0.86). In total, the advanced paramedics demonstrated an overall accuracy at identifying the presence or absence of pneumothorax in prerecorded video clip images of 0.82 (CI 0.77 to 0.86), in comparison
with the expert users of 0.80 (CI 0.68 to 0.88). All of the advanced paramedics passed the objective structured clinical examination and achieved a practical standard considered by the examiners to be equivalent to that which would be expected from candidates enrolled on the thoracic module of the College of Emergency Medicine level 2 ultrasound programme.

Conclusion This trial demonstrated that ultrasound-naive practitioners can achieve an acceptable standard of competency in a simulated environment in a relatively short period of time.

Acquisition and interpretation of focused diagnostic ultrasound images by ultrasound-naive advanced paramedics: trialling a PHUS education programme
Emerg Med J, 2012 vol. 29 (4) pp. 322-326

Only when I laugh

A middle-aged martial arts enthusiast was training in Krav Maga, and participated in a high-contact punching and grappling sparring exercise in which his (younger, heavier) partner threw him to the ground and landed on him. During the throw the patient felt a ‘pop’ in his right side, and wondered whether he’d fractured a rib. During the subsequent five rounds against two additional sparring partners he noticed a clicking in the same area every time he was grappling, and pain in the right side when pushing up off the floor with his right arm. As a trained emergency physician, he assessed his own level of breathing comfort throughout the training to reassure himself he didn’t have a significant pneumothorax, and therefore elected to continue to fight in the interests of assessing his ability to defend himself while injured.

Pain on deep inspiration, coughing, and squeezing the chest suggested a fractured rib, so out of curiosity at work the next day he ultrasounded the area of maximum tenderness:

Discontinuity in cortex signifies rib fracture

Examination of the lung confirmed pleural sliding, B-lines, and ‘pearls on a string’, which excluded pneumothorax.

Sonography is more sensitive than radiography for the detection of rib fractures and may also detect costochondral junction injuries and disruption of costal cartilage1. This video from Hennepin County Medical Centre takes you through the simple procedure:

Although the management of rib fractures is no different from that of chest wall contusion, knowledge of the presence of fracture in this case is helpful to this patient in deciding when to return to the questionably sane ‘hobby’ of fighting bigger guys half his age.

The patient’s consent was obtained prior to the publication of the ultrasound image.

1. Sonography Compared with Radiography in Revealing Acute Rib Fracture
AJR Am J Roentgenol. 1999 Dec;173(6):1603-9.
Full text article

OBJECTIVE: This study was undertaken to compare the sensitivities of sonography and radiography for revealing acute rib fracture.

SUBJECTS AND METHODS: Chest radiography and rib sonography were performed on 50 patients with suspected rib fractures. Sonography was performed with a 9- or 12-MHz linear transducer. Fractures were identified by a disruption of the anterior margin of the rib, costochondral junction, or costal cartilage. The incidence, location, and degree of displacement of fractures revealed by radiography and sonography were compared. Sonography was performed again after 3 weeks in 37 subjects.

RESULTS: At presentation, radiographs revealed eight rib fractures in six (12%) of 50 patients and sonography revealed 83 rib fractures in 39 (78%) of 50 patients. Seventy-four (89%) of the 83 sonographically detected fractures were located in the rib, four (5%) were located at the costochondral junction, and five (6%) in the costal cartilage. Repeated sonography after 3 weeks showed evidence of healing in all reexamined fractures. Combining sonography at presentation and after 3 weeks, 88% of subjects had sustained a fracture.

CONCLUSION: Sonography reveals more fractures than does radiography and will reveal fractures in most patients presenting with suspected rib fracture. Further scientific studies are needed to clarify the appropriate role for sonography in rib fracture detection.

International recommendations for lung ultrasound

A multidisciplinary panel of 28 experts from eight countries reviewed the literature and came up with consensus guidelines in point-of-care lung ultrasound. There were some big names involved – all the big players in emergency/critical care ultrasound from around the World. Conspicuously absent were Matt and Mike from the Emergency Ultrasound Podcast, but maybe there was a maximum awesomeness limit or something.

Here are some snippets, taken out of context and without the grade of recommendation attached. Try to get hold of the original if you can, which might not be easy. I never understand it when ‘international recommendations’ are published as subscription-only articles. Either they want people to follow them or not. Oh well – here are some of their recommendations:


  • The sonographic signs of pneumothorax include the following: Presence of lung point(s); Absence of lung sliding; Absence of B-lines; Absence of lung pulse
  • The lung pulse refers to the subtle rhythmic movement of the visceral upon the parietal pleura with cardiac oscillations and is a rule-out sign for pneumothorax
  • In the supine patient, the sonographic technique consists of exploration of the least gravitationally dependent areas progressing more laterally.
  • Bedside lung ultrasound is a useful tool to differentiate between small and large pneumothorax, using detection of the lung point.

Interstitial syndrome

  • B-lines are defined as discrete laser-like vertical hyperechoic reverberation artifacts that arise from the pleural line (previously described as ‘‘comet tails’’), extend to the bottom of the screen without fading, and move synchronously with lung sliding.
  • The presence of multiple diffuse bilateral B-lines indicates interstitial syndrome. Causes of interstitial syndrome include the following conditions: Pulmonary edema of various causes; Interstitial pneumonia or pneumonitis; Diffuse parenchymal lung disease (pulmonary fibrosis)

Lung consolidation

  • The sonographic sign of lung consolidation is a subpleural echo-poor region or one with tissue-like echotexture.
  • Lung ultrasound is a clinically useful tool to rule in pneumonia; however, lung ultrasound does not rule out consolidations that do not reach the pleura.
  • In mechanically ventilated patients lung ultrasound should be considered as it is more accurate than portable chest radiography in the detection of consolidation.

Pleural effusion

  • Both of the following signs are present in almost all free effusions: A space (usually anechoic) between the parietal and visceral pleura; Respiratory movement of the lung within the effusion (‘‘sinusoid sign’’)
  • In opacities identified by chest radiography, lung ultrasound should be used because it is more accurate than chest radiography in distinguishing between effusion and consolidation.
  • Visualization of internal echoes, either of mobile particles or septa, is highly suggestive of exudate or hemothorax

BACKGROUND: The purpose of this study is to provide evidence-based and expert consensus recommendations for lung ultrasound with focus on emergency and critical care settings.

METHODS: A multidisciplinary panel of 28 experts from eight countries was involved. Literature was reviewed from January 1966 to June 2011. Consensus members searched multiple databases including Pubmed, Medline, OVID, Embase, and others. The process used to develop these evidence-based recommendations involved two phases: determining the level of quality of evidence and developing the recommendation. The quality of evidence is assessed by the grading of recommendation, assessment, development, and evaluation (GRADE) method. However, the GRADE system does not enforce a specific method on how the panel should reach decisions during the consensus process. Our methodology committee decided to utilize the RAND appropriateness method for panel judgment and decisions/consensus.

RESULTS: Seventy-three proposed statements were examined and discussed in three conferences held in Bologna, Pisa, and Rome. Each conference included two rounds of face-to-face modified Delphi technique. Anonymous panel voting followed each round. The panel did not reach an agreement and therefore did not adopt any recommendations for six statements. Weak/conditional recommendations were made for 2 statements, and strong recommendations were made for the remaining 65 statements. The statements were then recategorized and grouped to their current format. Internal and external peer-review processes took place before submission of the recommendations. Updates will occur at least every 4 years or whenever significant major changes in evidence appear.

CONCLUSIONS: This document reflects the overall results of the first consensus conference on “point-of-care” lung ultrasound. Statements were discussed and elaborated by experts who published the vast majority of papers on clinical use of lung ultrasound in the last 20 years. Recommendations were produced to guide implementation, development, and standardization of lung ultrasound in all relevant settings.

International evidence-based recommendations for point-of-care lung ultrasound
Intensive Care Med. 2012 Apr;38(4):577-91

Spinal imaging for the adult obtunded blunt trauma patient

‘You can’t clear the cervical spine until the patient wakes up!’ How often have you heard this said about a patient with severe traumatic brain injury who may not ‘wake up’ for weeks, if at all?

A controversial area, but many institutions now allow collar removal if a neck CT scan is normal. Does this rule out injury with 100% sensitivity? No – but it probably pushes the balance of risk towards removing the collar – an intervention with no evidence for benefit and plenty of reasons why it may be harmful to ventilated ICU patients. For example, clearing the cervical spine based on MDCT was associated with less delirium and less ventilator associated pneumonia, both of which have been associated with increased mortality in critically ill patients (this is referenced in the paper below).

The UK’s Intensive Care Society has had pragmatic guidelines along these lines since 2005, which can be found here. This month’s Intensive Care Medicine publishes an updated literature review providing some further support to this approach.

PURPOSE: Controversy exists over how to ‘clear’ (we mean enable the clinician to safely remove spinal precautions based on imaging and/or clinical examination) the spine of significant unstable injury among clinically unevaluable obtunded blunt trauma patients (OBTPs). This review provides a clinically relevant update of the available evidence since our last review and practice recommendations in 2004.

METHODS: Medline, Embase. Google Scholar, BestBETs, the trip database, BMJ clinical evidence and the Cochrane library were searched. Bibliographies of relevant studies were reviewed.

RESULTS: Plain radiography has low sensitivity for detecting unstable spinal injuries in OBTPs whereas multidetector-row computerised tomography (MDCT) approaches 100%. Magnetic resonance imaging (MRI) is inferior to MDCT for detecting bony injury but superior for detecting soft tissue injury with a sensitivity approaching 100%, although 40% of such injuries may be stable and ‘false positive’. For studies comparing MDCT with MRI for OBTPs; MRI following ‘normal’ CT may detect up to 7.5% missed injuries with an operative fixation in 0.29% and prolonged collar application in 4.3%. Increasing data is available on the complications associated with prolonged spinal immobilisation among a population where a minority have an actual injury.

CONCLUSIONS: Given the variability of screening performance it remains acceptable for clinicians to clear the spine of OBTPs using MDCT alone or MDCT followed by MRI, with implications to either approach. Ongoing research is needed and suggestions are made regarding this. It is essential clinicians and institutions audit their data to determine their likely screening performances in practice.

Clinical review: spinal imaging for the adult obtunded blunt trauma patient: update from 2004
Intensive Care Med. 2012 Mar 10. [Epub ahead of print]

Prehospital echo predicts arrest outcome

In hospital, the detection of cardiac standstill with ultrasound predicts a fatal outcome from cardiac arrest with a high degree of accuracy. A similar finding has been made in the prehospital setting. Interestingly, it was a better predictor than other commonly recognised factors associated with outcome: the presence of asystole, down time, bystander CPR, or end-tidal CO2 levels.

Introduction. The prognostic value of emergency echocardiography (EE) in the management of cardiac arrest patients has previously been studied in an in-hospital setting. These studies mainly included patients who underwent cardiopulmonary resuscitation (CPR) by emergency medicine technicians at the scene and who arrived at the emergency department (ED) still in a state of cardiac arrest. In most European countries, cardiac arrest patients are normally treated by physician-staffed emergency medical services (EMS) teams on scene. Transportation to the ED while undergoing CPR is uncommon. Objective. To evaluate the ability of EE to predict outcome in cardiac arrest patients when it is performed by ultrasound-inexperienced emergency physicians on scene.

Methods. We performed a prospective, observational study of nonconsecutive, nontrauma, adult cardiac arrest patients who were treated by physician-staffed urban EMS teams on scene. Participating emergency physicians (EPs) received a two-hour course in EE during CPR. After initial procedures were accomplished, EE was performed during a rhythm and pulse check. A single subxiphoid, four-chamber view was required for study enrollment. We defined sonographic evidence of cardiac kinetic activity as any detected motion of the myocardium, ranging from visible ventricular fibrillation to coordinated ventricular contractions. The CPR had to be continued for at least 15 minutes after the initial echocardiography. No clinical decisions were made based on the results of EE.

Results. Forty-two patients were enrolled in the study. The heart could be visualized successfully in all patients. Five (11.9%) patients survived to hospital admission. Of the 32 patients who had cardiac standstill on initial EE, only one (3.1%) survived to hospital admission, whereas four out of 10 (40%) patients with cardiac movement on initial EE survived to hospital admission (p = 0.008). Neither asystole on initial electrocardiogram nor peak capnography value, age, bystander CPR, or downtime was a significant predictor of survival. Only cardiac movement was associated with survival, and cardiac standstill at any time during CPR resulted in a positive predictive value of 97.1% for death at the scene.

Conclusion. Our results support the idea of focused echocardiography as an additional criterion in the evaluation of outcome in CPR patients and demonstrate its feasibility in the prehospital setting.

Cardiac Movement Identified on Prehospital Echocardiography Predicts Outcome
Prehosp Emerg Care. 2012 Jan 11. [Epub ahead of print]

Ultrasound for pneumonia

Lung ultrasound done by a single keen individual had better test characteristics than CXR in diagnosing pneumonia as defined by discharge diagnosis.
The lung ultrasound was considered to be positive for pneumonia if it showed consolidation (including air bronchograms) or a focal interstitial syndrome (localised increased density of ‘B’ lines)

Objective The aim of this study was to evaluate the diagnostic accuracy of bedside lung ultrasound and chest radiography (CXR) in patients with suspected pneumonia compared with CT scan and final diagnosis at discharge.

Design A prospective clinical study.

Methods Lung ultrasound and CXR were performed in sequence in adult patients admitted to the emergency department (ED) for suspected pneumonia. A chest CT scan was performed during hospital stay when clinically indicated.

Results 120 patients entered the study. A discharge diagnosis of pneumonia was confirmed in 81 (67.5%). The first CXR was positive in 54/81 patients (sensitivity 67%; 95% CI 56.4% to 76.9%) and negative in 33/39 (specificity 85%; 95% CI 73.3% to 95.9%), whereas lung ultrasound was positive in 80/81 (sensitivity 98%; 95% CI 93.3% to 99.9%) and negative in 37/39 (specificity 95%; 95% CI 82.7% to 99.4%). A CT scan was performed in 30 patients (26 of which were positive for pneumonia); in this subgroup the first CXR was diagnostic for pneumonia in 18/26 cases (sensitivity 69%), whereas ultrasound was positive in 25/26 (sensitivity 96%). The feasibility of ultrasound was 100% and the examination was always performed in less than 5 min.

Conclusions Bedside chest ultrasound is a reliable tool for the diagnosis of pneumonia in the ED, probably being superior to CXR in this setting. It is likely that its wider use will allow a faster diagnosis, conducive to a more appropriate and timely therapy.

Lung ultrasound is an accurate diagnostic tool for the diagnosis of pneumonia in the emergency department
Emerg Med J. 2012 Jan;29(1):19-23

Potassium levels and AMI death

An association is demonstrated between abnormal (both high and low) serum potassium levels and in-hospital mortality in patients with acute myocardial infarction. These findings do not necessarily imply a causal relationship, since abnormal potassium levels might be a marker of increased risk of death due to other illness factors rather than a risk of death per se.

Acknowledging that a randomised trial of potassium replacement is unlikely to happen, the authors pragmatically advise:

Our data suggest that the optimal range of serum potassium levels in AMI patients may be between 3.5 and 4.5 mEq/L and that potassium levels of greater than 4.5 mEq/L are associated with increased mortality and should probably be avoided.

Context Clinical practice guidelines recommend maintaining serum potassium levels between 4.0 and 5.0 mEq/L in patients with acute myocardial infarction (AMI). These guidelines are based on small studies that associated low potassium levels with ventricular arrhythmias in the pre−β-blocker and prereperfusion era. Current studies examining the relationship between potassium levels and mortality in AMI patients are lacking.

Objective To determine the relationship between serum potassium levels and in-hospital mortality in AMI patients in the era of β-blocker and reperfusion therapy.

Design, Setting, and Patients Retrospective cohort study using the Cerner Health Facts database, which included 38 689 patients with biomarker-confirmed AMI, admitted to 67 US hospitals between January 1, 2000, and December 31, 2008. All patients had in-hospital serum potassium measurements and were categorized by mean postadmission serum potassium level (<3.0, 3.0-<3.5, 3.5-<4.0, 4.0-<4.5, 4.5-<5.0, 5.0-<5.5, and ≥5.5 mEq/L). Hierarchical logistic regression was used to determine the association between potassium levels and outcomes after adjusting for patient- and hospital-level factors.

Main Outcome Measures All-cause in-hospital mortality and the composite of ventricular fibrillation or cardiac arrest.

Results There was a U-shaped relationship between mean postadmission serum potassium level and in-hospital mortality that persisted after multivariable adjustment. Compared with the reference group of 3.5 to less than 4.0 mEq/L (mortality rate, 4.8%; 95% CI, 4.4%-5.2%), mortality was comparable for mean postadmission potassium of 4.0 to less than 4.5 mEq/L (5.0%; 95% CI, 4.7%-5.3%), multivariable-adjusted odds ratio (OR), 1.19 (95% CI, 1.04-1.36). Mortality was twice as great for potassium of 4.5 to less than 5.0 mEq/L (10.0%; 95% CI, 9.1%-10.9%; multivariable-adjusted OR, 1.99; 95% CI, 1.68-2.36), and even greater for higher potassium strata. Similarly, mortality rates were higher for potassium levels of less than 3.5 mEq/L. In contrast, rates of ventricular fibrillation or cardiac arrest were higher only among patients with potassium levels of less than 3.0 mEq/L and at levels of 5.0 mEq/L or greater.

Conclusion Among inpatients with AMI, the lowest mortality was observed in those with postadmission serum potassium levels between 3.5 and <4.5 mEq/L compared with those who had higher or lower potassium levels.

Serum Potassium Levels and Mortality in Acute Myocardial Infarction
JAMA Jan 11 2012,307(2):115-213

Predicting massive transfusion

Do you have access to thromboelastometry in your Emergency Department? Further research by some of the first discoverers of acute traumatic coagulopathy involved using this tool to identify acute traumatic coagulopathy at 5 mins and predict the need for massive transfusion. Measures of coagulopathy more familiar to ED staff such as the INR took longer or (when point-of-care testing was employed) were less accurate.

OBJECTIVE: To identify an appropriate diagnostic tool for the early diagnosis of acute traumatic coagulopathy and validate this modality through prediction of transfusion requirements in trauma hemorrhage.

DESIGN: Prospective observational cohort study.

SETTING: Level 1 trauma center.

PATIENTS: Adult trauma patients who met the local criteria for full trauma team activation. Exclusion criteria included emergency department arrival >2 hrs after injury, >2000 mL of intravenous fluid before emergency department arrival, or transfer from another hospital.


MEASUREMENTS: Blood was collected on arrival in the emergency department and analyzed with laboratory prothrombin time, point-of-care prothrombin time, and rotational thromboelastometry. Prothrombin time ratio was calculated and acute traumatic coagulopathy defined as laboratory prothrombin time ratio >1.2. Transfusion requirements were recorded for the first 12 hrs following admission.

MAIN RESULTS: Three hundred patients were included in the study. Laboratory prothrombin time results were available at a median of 78 (62-103) mins. Point-of-care prothrombin time ratio had reduced agreement with laboratory prothrombin time ratio in patients with acute traumatic coagulopathy, with 29% false-negative results. In acute traumatic coagulopathy, the rotational thromboelastometry clot amplitude at 5 mins was diminished by 42%, and this persisted throughout clot maturation. Rotational thromboelastometry clotting time was not significantly prolonged. Clot amplitude at a 5-min threshold of ≤35 mm had a detection rate of 77% for acute traumatic coagulopathy with a false-positive rate of 13%. Patients with clot amplitude at 5 mins ≤35 mm were more likely to receive red cell (46% vs. 17%, p < .001) and plasma (37% vs. 11%, p < .001) transfusions. The clot amplitude at 5 mins could identify patients who would require massive transfusion (detection rate of 71%, vs. 43% for prothrombin time ratio >1.2, p < .001).

CONCLUSIONS: In trauma hemorrhage, prothrombin time ratio is not rapidly available from the laboratory and point-of-care devices can be inaccurate. Acute traumatic coagulopathy is functionally characterized by a reduction in clot strength. With a threshold of clot amplitude at 5 mins of ≤35 mm, rotational thromboelastometry can identify acute traumatic coagulopathy at 5 mins and predict the need for massive transfusion.

Functional definition and characterization of acute traumatic coagulopathy.
Crit Care Med. 2011 Dec;39(12):2652-2658

Delayed diagnosis of aortic dissection

Being female or having atypical pain is associated with delays to diagnosis of aortic dissection. This recent study also shows that arrival in a non-tertiary hospital is another factor associated with delayed diagnosis. Patients may present with fever, abdominal pain, or heart failure (due to acute aortic insufficiency) that lead the clinician down alternative diagnostic algorithms. The strongest factors associated with operative delay were prolonged time from presentation to diagnosis, race other than white, and history of coronary artery bypass surgery.

Worth remembering at this point that in 2010 the AHA published Guidelines for the Diagnosis and Management of Patients With Thoracic Aortic Disease

Background- In acute aortic dissection, delays exist between presentation and diagnosis and, once diagnosed, definitive treatment. This study aimed to define the variables associated with these delays.

Methods and Results- Acute aortic dissection patients enrolled in the International Registry of Acute Aortic Dissection (IRAD) between 1996 and January 2007 were evaluated for factors contributing to delays in presentation to diagnosis and in diagnosis to surgery. Multiple linear regression was performed to determine relative delay time ratios (DTRs) for individual correlates. The median time from arrival at the emergency department to diagnosis was 4.3 hours (quartile 1-3, 1.5-24 hours; n=894 patients) and from diagnosis to surgery was 4.3 hours (quartile 1-3, 2.4-24 hours; n=751). Delays in acute aortic dissection diagnosis occurred in female patients; those with atypical symptoms that were not abrupt or did not include chest, back, or any pain; patients with an absence of pulse deficit or hypotension; or those who initially presented to a nontertiary care hospital (all P<0.05). The largest relative DTRs were for fever (DTR=5.11; P<0.001) and transfer from nontertiary hospital (DTR=3.34; P<0.001). Delay in time from diagnosis to surgery was associated with a history of previous cardiac surgery, presentation without abrupt or any pain, and initial presentation to a nontertiary care hospital (all P<0.001). The strongest factors associated with operative delay were prolonged time from presentation to diagnosis (DTR=1.35; P<0.001), race other than white (DTR=2.25; P<0.001), and history of coronary artery bypass surgery (DTR=2.81; P<0.001).

Conclusions- Improved physician awareness of atypical presentations and prompt transport of acute aortic dissection patients could reduce crucial time variables.

Correlates of Delayed Recognition and Treatment of Acute Type A Aortic Dissection: The International Registry of Acute Aortic Dissection (IRAD)
Circulation. 2011 Nov 1;124(18):1911-1918

‘Cryptic shock’ important but not always very cryptic

Patients with severe sepsis and an elevated lactate who appear to be normotensive had a mortality similar to those presenting with hypotension. This is demonstrated in a new study on patients who were recruited to a study I have reported before.

The so-called ‘cryptic shock’ group was defined by a systolic BP of at least 90 mmHg, suggesting to me not so much that normotension and hypotension are prognostically equivalent, but that we should perhaps redefine hypotension in sepsis, as we should probably be doing in trauma. Alternatively (and preferably), the BP should be interpreted in the context of what is known to be or likely to be normal for that patient. For example, a systolic BP of 105 mmHg in a 75 year old male would be be ringing serious alarm bells for me in a febrile patient, and I would be working them up for severe sepsis from the start. Interestingly in this study, the cryptic shock group had a higher proportion of patients with diabetes and/or end stage renal disease – diagnoses one would expect to be associated with hypertension – and the median (and IQR) systolic BP in this group was 108 (92, 126). So, although this shock may have been ‘cryptic’ as opposed to ‘overt’ by the definition applied in the paper (a cut off of 90 mmHg), it is likely that some of the patients in the cryptic group were hypotensive compared with their usual blood pressure.

These observations do not detract from a key message the authors include in their discussion, with which I wholeheartedly agree:

“These data highlight the need to screen patients for signs of occult hypoperfusion, and given the high mortality rate associated with an elevated serum lactate, also suggest that patients with biochemical evidence of inadequate oxygen delivery despite normal blood pressure should be included in early sepsis resuscitation pathways.”

This paper makes an important contribution to the sepsis literature by warning against the dismissal of an elevated serum lactate in the setting of apparent haemodynamic stability as being a less acutely ill patient than one presenting with overt hypotension. It provides a reminder to check the lactate in patients with infection and signs of systemic inflammatory response, since this may provide the only early evidence of hypoperfusion.

Outcomes of patients undergoing early sepsis resuscitation for cryptic shock compared with overt shock

Resuscitation. 2011 Oct;82(10):1289-1293

Introduction We sought to compare the outcomes of patients with cryptic versus overt shock treated with an emergency department (ED) based early sepsis resuscitation protocol.

Methods Pre-planned secondary analysis of a large, multicenter ED-based randomized controlled trial of early sepsis resuscitation. All subjects were treated with a quantitative resuscitation protocol in the ED targeting 3 physiological variables: central venous pressure, mean arterial pressure and either central venous oxygen saturation or lactate clearance. The study protocol was continued until all endpoints were achieved or a maximum of 6 h. Outcomes data of patients who were enrolled with a lactate ≥4 mmol/L and normotension (cryptic shock) were compared to those enrolled with sustained hypotension after fluid challenge (overt shock). The primary outcome was in-hospital mortality.

Results A total of 300 subjects were enrolled, 53 in the cryptic shock group and 247 in the overt shock group. The demographics and baseline characteristics were similar between the groups. The primary endpoint of in-hospital mortality was observed in 11/53 (20%, 95% CI 11–34) in the cryptic shock group and 48/247 (19%, 95% CI 15–25) in the overt shock group, difference of 1% (95% CI −10 to 14; log rank test p = 0.81).

Conclusion Severe sepsis with cryptic shock carries a mortality rate not significantly different from that of overt septic shock. These data suggest the need for early aggressive screening for and treatment of patients with an elevated serum lactate in the absence of hypotension.