Previous work in severe sepsis/septic shock patients has shown that a decrease in lactate concentration by at least 10% during emergency department resuscitation predicts survival. Since this is a potential alternative resuscitation goal to a central venous oxygen saturation (ScvO2) of 70% (as per surviving sepsis campaign guidelines), lactate clearance was compared with ScvO2 in a randomised non-inferiority trial of 300 patients.
All patients were managed in the ED and received fluids, antibiotics, and vasopressors as needed. Then lactate clearance or ScvO2 were measured, and if the respective goals of 10% or 70% were not met, packed cells or dobutamine were given depending on haematocrit. Lactate clearance was the percentage decrease in lactate between two venous specimens taken two hours apart.
Interestingly only 29 patients received either packed cells or dobutamine. Each group was similar in terms of time to antibiotic therapy and amount of fluid given. Patients in the group resuscitated to a lactate clearance of 10% or higher had 6% lower in-hospital mortality than those resuscitated to an ScvO2 of at least 70% (95% CI for this difference, –3% to 15%) exceeding the –10% predefined noninferiority threshold.
The authors conclude ‘these data support the substitution of lactate measurements in peripheral venous blood as a safe and efficacious alternative to a computerized spectrophotometric catheter in the resuscitation of sepsis.’
Lactate clearance vs central venous oxygen saturation as goals of early sepsis therapy: a randomized clinical trial
JAMA. 2010 Feb 24;303(8):739-46
Category Archives: ICU
Stuff relevant to patients on ICU
Chlorhexidine-alcohol surgical site prep
In contrast to the situation with skin preparation for intravascular catheters, there have been no recommendations for surgical practice. A randomised controlled trial compared chlorhexidine–alcohol (2% chlorhexidine gluconate and 70% isopropyl alcohol or ‘ChloraPrep’) with povidone–iodine in 849 patients undergoing surgery. The overall rate of surgical-site infection was significantly lower in the chlorhexidine–alcohol group than in the povidone–iodine group (9.5% vs. 16.1%) and chlorhexidine–alcohol was significantly more protective than povidone–iodine against both superficial incisional infections (4.2% vs. 8.6%) and deep incisional infections (1% vs. 3%) but not against organ-space infections (4.4% vs. 4.5%)
Chlorhexidine-Alcohol versus Povidone-Iodine for Surgical-Site Antisepsis
N Engl J Med. 2010 Jan 7;362(1):18-26
Noradrenaline vs Dopamine in Shock
Another nail in dopamine’s coffin? In a blinded randomised controlled trial in shocked patients1, there was no difference in mortality when dopamine was compared with noradrenaline as the initial vasopressor. However the dopamine group had a significantly higher incidence of dysrythmia. In addition, mortality was higher in the predefined subgroup of 280 patients with cardiogenic shock. The results of this European study of 1679 patients are very similar to those of a similar but open-label American trial in 252 patients published recently2.
1. Comparison of Dopamine and Norepinephrine in the Treatment of Shock
NEJM 2010;362(9):779-89
2. Efficacy and Safety of Dopamine versus Norepinephrine in the Management of Septic Shock
Shock. 2009 Oct 21. [Epub ahead of print]
Supraclavicular approach to subclavian vein
A series of subclavian vein catheterisations is described in patients using the supraclavicular approach, with a high success rate and few complications. 290 of the 370 patients were mechanically ventilated at the time of the procedure
How they did it:
- The point of needle insertion was identified 1 cm cephalad and 1 cm lateral to the junction of the lateral margin of the clavicular head of the sternocleidomastoid muscle with the superior margin of the clavicle (claviculosternocleidomastoid angle)
- The direction of the needle was indicated by the line that bisects the claviculosternocleidomastoid angle with elevation 5–15 degrees above the coronal plane.
- The needle was advanced slowly with a constant negative pressure in the syringe.
- The vein was usually punctured between the clavicle and the attachment of the anterior scalene muscle to the first rib.
- The subclavian artery is situated posterior and slightly superior to the vein; if palpable, the pulse of the artery could be the important landmark
- The depth of catheter insertion was 14 cm for right side and 18 cm for left side catheterization.
Supraclavicular approach is an easy and safe method of subclavian vein catheterization even in mechanically ventilated patients: analysis of 370 attempts
Anesthesiology. 2009 Aug;111(2):334-9
EMRAP.TV has a video on supraclavicular central line insertion here
Some causes of a raised lactate
A high serum lactate does not necessarily mean a bad prognosis: it all depends on the cause.
I made this diagram as a mnemonic for the causes of high lactates:
Additional information added 1st June 2011: One cause of an elevated lactate may be artefactual, secondary to interference with the assay (used on ABG machines) by ethylene glycol. The assay may also be subject to interference from certain drugs at toxic levels such as isoniazid, acetaminophen and thiocyanate. This information is from the Renal Fellow Network.
Subarachnoid haemorrhage guidelines
Guidelines on Subarachnoid Haemorrhage are available from the American Heart Association / American Stroke Association.
Most of the summaries are included below.
The initial bleed
The severity of the initial bleed should be determined rapidly because it is the most useful indicator of outcome after aneurysmal SAH, and grading scales that rely heavily on this factor are helpful in planning future care with family and other physicians
Case review and prospective cohorts have shown that for untreated, ruptured aneurysms, there is at least a 3% to 4% risk of rebleeding in the first 24 hours—and possibly significantly higher—with a high percentage occurring immediately (within 2 to 12 hours) after the initial ictus, a 1% per day to 2% per day risk in the first month, and a long-term risk of 3% per year after 3 months. Urgent evaluation and treatment of patients with suspected SAH are therefore recommended
Diagnosis
- A high level of suspicion for SAH should exist in patients with acute onset of severe headache
- CT scanning for suspected SAH should be performed, and lumbar puncture for analysis of CSF is strongly recommended when the CT scan is negative
- Selective cerebral angiography should be performed in patients with SAH to document the presence and anatomic features of aneurysms
- MRA and CTA may be considered when conventional angiography cannot be performed in a timely fashion
The degree of neurological impairment using an accepted SAH grading system can be useful for prognosis and triage and should be recorded in the ED. Examples include the Hunt and Hess Scale, Fisher Scale, Glasgow Coma Scale, and World Federation of Neurological Surgeons Scale.
Medical Measures to Prevent Rebleeding After SAH
- Blood pressure should be monitored and controlled to balance the risk of stroke, hypertension-related rebleeding, and maintenance of cerebral perfusion pressure
- Bedrest alone is not enough to prevent rebleeding after SAH. It may be considered a component of a broader treatment strategy, along with more definitive measures
- Although older studies demonstrated an overall negative effect of antifibrinolytics, recent evidence suggests that early treatment with a short course of antifibrinolytic agents combined with a program of early aneurysm treatment followed by discontinuation of the antifibrino- lytic and prophylaxis against hypovolemia and vasospasm may be reasonable, but further research is needed. Furthermore, antifibrinolytic therapy to prevent rebleeding may be considered in certain clinical situations, eg, in patients with a low risk of vasospasm and/or a beneficial effect of delaying surgery.
Surgical treatment
- Surgical clipping or endovascular coiling should be per- formed to reduce the rate of rebleeding after aneurysmal SAH
- Wrapped or coated aneurysms and incompletely clipped or coiled aneurysms have an increased risk of rehemorrhage compared with those that are completely occluded and therefore require long-term follow-up angiography. Com- plete obliteration of the aneurysm is recommended whenever possible
- For patients with ruptured aneurysms judged by an experienced team of cerebrovascular surgeons and endovascu- lar practitioners to be technically amenable to both endovascular coiling and neurosurgical clipping, endovascular coiling can be beneficial. Nevertheless, it is reasonable to consider individual characteristics of the patient and the aneurysm in deciding the best means of repair, and management of patients in centers offering both techniques is probably indicated
- Although previous studies showed that overall outcome was not different for early versus delayed surgery after SAH, early treatment reduces the risk of rebleeding after SAH, and newer methods may increase the effectiveness of early aneurysm treatment. Early aneurysm treatment is reasonable and is probably indicated in the majority of cases
Management of Cerebral Vasospasm
- Oral nimodipine is indicated to reduce poor outcome related to aneurysmal SAH. The value of other calcium antagonists, whether administered orally or intravenously, remains uncertain.
- Treatment of cerebral vasospasm begins with early management of the ruptured aneurysm, and in most cases, maintaining normal circulating blood volume and avoiding hypovolemia are probably indicated
- One reasonable approach to symptomatic cerebral vasospasm is volume expansion, induction of hypertension, and hemodilution (triple-H therapy)
- Alternatively, cerebral angioplasty and/or selective intraarterial vasodilator therapy may be reasonable after, together with, or in the place of triple-H therapy, depending on the clinical scenario
Management of Hydrocephalus
Temporary or permanent CSF diversion is recommended in symptomatic patients with chronic hydrocephalus after SAH
Ventriculostomy can be beneficial in patients with ven- triculomegaly and diminished level of consciousness after acute SAH
Management of Seizures
The administration of prophylactic anticonvulsants may be considered in the immediate posthemorrhagic period
Management of Hyponatremia
- Administration of large volumes of hypotonic fluids and intravascular volume contraction should generally be avoided after SAH
- Monitoring volume status in certain patients with recent SAH using some combination of central venous pressure, pulmonary artery wedge pressure, fluid balance, and body weight is reasonable, as is treatment of volume contraction with isotonic fluids
- The use of fludrocortisone acetate and hypertonic saline is reasonable for correcting hyponatremia
- In some instances, it may be reasonable to reduce fluid administration to maintain a euvolemic state
Guidelines for the Management of Aneurysmal Subarachnoid Hemorrhage: A Statement for Healthcare Professionals From a Special Writing Group of the Stroke Council, American Heart Association
Stroke 2009;40;994-1025 (Full Text)
Other AHA Stroke Guidelines
Standards for Capnography in Critical Care
The Intensive Care Society has published guidelines on the use of capnography in critical care. The recommendations are:
- Capnography should be used for all critically ill patients during the procedures of tracheostomy or endotracheal intubation when performed in the intensive care unit.
- Capnography should be used in all critically ill patients who require mechanical ventilation during inter-hospital or intra- hospital transfer.
- Rare situations in which capnography is misleading can be reduced by increasing staff familiarity with the equipment, and by the use of bronchoscopy to confirm tube placement where the tube may be displaced but remains in the respiratory tract.
Other findings:
- Capnography offers the potential for non-invasive measurement of additional physiological variables including physiological dead space and total CO2 production.
- Capnography is not a substitute for estimation of arterial CO2.
- Careful consideration should be given to the type of capnography that should be used in an ICU. The decision will be influenced by methods used for humidification, and the advantages of active or passive humidification should be reviewed.
- Capnometry is an alternative to capnography where capnography is not available, for example where endotracheal intubation is required in general ward areas.
ScvO2 in sepsis: high is bad too
ScvO2 values are obtained by measuring the oxygen saturation in venous blood returning to the heart, and reflect the balance between oxygen delivery and oxygen consumption.
Low (<70%) ScvO2 values were targeted by Rivers in his Early Goal Directed Therapy study: by improving the macrocirculation with fluids, vasoactive drugs, and packed red cells the aim is to improve oxygen delivery to tissues, and therefore a higher oxygen saturation is found in the venous blood returning to the heart in adequately resuscitated patients. The story is more complex, however, as mechanisms of oxygen supply (macrocirculatory flow), distribution (microcirculatory flow), and processing (mitochondrial function) must all function at an adequate level to maintain normal physiology.
Although low ScvO2 values may be a marker for macrocirculatory failure, high ScvO2 values may reflect microcirculatory or mitochondrial failure.
A multicentre study demonstrated a higher mortality on patients whose ScvO2 in the ED was high (90-100%) compared with those with a normal ScvO2.
Mortality associated with three groups according to their highest recorded ScvO2 in the ED was:
Hypoxia group (ScvO2 <70%) – 40% mortality (95% CI 29-53)
Normoxia group (ScvO2 71-89%) – 21% mortality (95% CI 17-25)
Hyperoxia group (ScvO2 90-100%) – 34% mortality (95% CI 25-44)
The study design could not control for many potential confounders, but this opens the door for further study, and reminds us that the unthinking pursuit of a single physiological target may miss the bigger clinical picture.
Multicenter Study of Central Venous Oxygen Saturation (ScvO2) as a Predictor of Mortality in Patients With Sepsis
Annals of Emergency Medicine 2010;55(1):40-46
Therapeutic hypothermia with simple measures
Thirty-eight post-cardiac arrest patients were effectively cooled to the target temperature range of 32-34 celsius using intravenous cold saline and ice packs to groin, axillae, and neck. The ice packs were frozen 250 ml saline bags wrapped in pillow cases. If shivering occurred muscle relaxation with rocuronium was used until the target temperature was reached. Interestingly, rebound hyperthermia occurred in 8/34 patients.
Although a small study, these data reassure those of us who induce therapeutic hypothermia without the use of dedicated cooling equipment.
Cold saline infusion and ice packs alone are effective in inducing and
maintaining therapeutic hypothermia after cardiac arrest
Resuscitation 2010;81:15–19
Updated Nutrition Guidelines
The Canadian Clinical Practice Guidelines for nutrition in the critically ill patient were updated in 2009 and the summary can be found here