|Year : 2016 | Volume
| Issue : 4 | Page : 245-249
Critical care bundles: Significance and outcomes
Pradeep Pendyala1, Padmanabha TVSP Murthy2
1 Department of Anesthesiology, Malla Reddy Institute of Medical Sciences, Suraram, Hyderabad, India
2 Department of Anaesthesia, Armed Forces Medical College (AFMC), Pune, Maharashtra, India
|Date of Web Publication||23-Dec-2016|
Former HOD, Assistant Professor, Department of Anesthesiology, Malla Reddy Institute of Medical Sciences, Suraram, Hyderabad - 500 055, Telangana
Source of Support: None, Conflict of Interest: None
A critical care bundle comprises a group of interventions which have been shown to improve outcome, which are achievable, measurable and not yet performed in the majority of patients. The principle is that the benefit to a patient of the whole care bundle is greater than the sum of the parts.
Keywords: Sepsis resuscitation bundle, sepsis management bundle, surviving sepsis
|How to cite this article:|
Pendyala P, Murthy PT. Critical care bundles: Significance and outcomes. J NTR Univ Health Sci 2016;5:245-9
| Bundles|| |
The Institute for Healthcare Improvement  in collaboration with Surviving Sepsis Campaign developed two "bundles" or packages of care for the treatment of those with severe sepsis.
The severe sepsis resuscitation bundle is to be complete in 6 h following the recognition of severe sepsis.
The severe sepsis management bundle is to be complete in 24 h.
Essentially, a care bundle is a package of care. A typical care bundle will have between four and eight elements of care. From a research point of view, the beauty of a care bundle is that it is easily measurable: A patient will either satisfy the whole care bundle or he/she will not.
For a care bundle to be effective, it must satisfy the following criteria: 
In other words, a care bundle comprises a group of interventions that have been shown to improve outcome and which are achievable, measurable, and have not yet performed in the majority of patients. The principle is that the benefit to a patient of the whole care bundle is greater than the sum of the parts.
- Each element must be based on sound evidence.
- The delivery of each element must be in need of improvement.
- To deliver, each element must be achievable in terms of resources.
- No element should be a major source of controversy.
- The bundle as a whole must do more good than harm.
- The delivery of each element must be measurable.
| The surviving sepsis campaign resuscitation bundle|| |
In its raw form, the resuscitation bundle is summarized as follows:
- Measurement of serum lactate.
- Blood culture prior to antibiotic administration.
- Administration of broad spectrum antibiotics within 1 h of admission.
- Treatment of hypotension/increased lactate with fluids:
In case of persistent hypotension despite adequate fluid resuscitation and/or increased lactate of more than 4 mmol/L, adequate central venous pressure and central venous oxygen saturation should be maintained. Central venous pressure (CVP) more than 8 mmHg and central venous oxygen saturation of more than 70% or mixed venous saturation of more than 65% should be maintained.The bundle is designed to be completed within 6 h following the onset of severe sepsis.
- Delivering an initial amount of 20 mL/kg crystalloid or equivalent.
- Vasopressor for hypotension not responding to fluids.
- Maintenance of mean arterial pressure (MAP) more than 65 mmHg.
| Elements of the resuscitation bundle|| |
Lactate or lactic acid is the product of anaerobic metabolism of glucose by the tissues. This process is less efficient than aerobic metabolism in terms of adenosine triphosphate (ATP) production per unit of substrate, and occurs when insufficient oxygen is delivered to the tissues. There is good evidence that lactate carries prognostic value. Patients with lactate measurement in excess of 4 mmol/L had a mortality of around 40%, compared with under 15% for patients with a lactate of <2 mmol/L. Lactate is particularly useful when measured serially to guide response to resuscitation and fluid therapy. It should be noted that lactate is not specific to organ hypoperfusion secondary to severe sepsis. Indeed, some units prefer serum procalcitonin as a more specific marker.  It is perfectly acceptable to use a surrogate marker of tissue hypoperfusion in achieving the resuscitation bundle.
Blood cultures obtained prior to antibiotic administration
Two or more blood cultures are recommended, one drawn percutaneously and one through each vascular access device if it has been in for longer than 48 h. The rationale behind this is that if the culture from the access device is positive earlier than that for the percutaneous sample, the device may well be the source of infection.  Similarly, if the same organism is isolated from more than one culture, the chance that this is the organism responsible for the sepsis is elevated.  It is also recommended that consideration be given to sampling of other biofluids such as cerebrospinal fluid, sputum, urine, synovial fluid, pleural fluid where the clinical signs point to a source of infection.
The surviving sepsis campaign (SSC) bundle stipulates that antibiotics should be given within 1 h. There is ample evidence to support early and appropriate antibiotic administration, such that it can be argued that this is one of the most important aspects of either care bundle. A large retrospective study showed that in patients with septic shock, delay in the administration of antibiotic was associated with an increase in mortality of 7.6% for each hour's delay.  Antibiotics should be administered according to local pathogen profiles, taking into account the knowledge of local resistance patterns and organisms. One or more broad spectrum antibiotics should be administered in the first instance, with a review and probable change to a narrower spectrum once the causative organism has been isolated.
Fluids should be administered intravenously in volumes of 500-1,000 mL if crystalloids are used, and 300-500 mL if colloids are used. There is little evidence to support the use of colloids over crystalloids , Colloids have a smaller volume of distribution than crystalloids and thus, less volume is required to achieve the same degree of intravascular volume expansion. Patients with severe sepsis frequently require large volumes of fluids for adequate resuscitation, and are likely to have ongoing requirements far exceeding the usual maintenance fluids for at least the first 24 h. Input will almost always exceed output within this early phase, and fluid balance is a poor estimate of fluid requirement at this stage. It is appropriate to give large volumes of fluid, particularly in the presence of shock, provided the patient is monitored closely and frequently reassessed for signs of fluid overload and pulmonary edema. In hypoperfused patients, a minimum volume of 20 mL/kg is recommended as an initial bolus. Patients with shock will frequently require volumes of up to 60 mL/kg in resuscitation; for an average adult male, this represents nearly 5 L of intravenous fluid.
Early goal-directed therapy
The remainder of the resuscitation bundle falls under the umbrella of early goal-directed therapy (EGDT). The concept of goal-directed therapy in anesthesia and critical care is not new.  Essentially, the term refers to the manipulation of physiology through intervention to achieve predetermined goals. Early intervention may help prevent a catastrophic and irreversible decline. This is logical because the rationale behind resuscitating a patient is to prevent further organ dysfunction and failure. If resuscitation is delayed until after cell dysfunction and death are present, then strategies such as these designed to provide the cells with more oxygen will not work.
Oxygen supply and delivery
In septic shock the abnormalities in the circulation - intravascular volume depletion, peripheral vasodilatation, capillary shunting, edema, impaired mitochondrial oxygen transport, and myocardial depression, along with the increased metabolism, lead to an imbalance between the delivery of oxygen to the tissues and oxygen demand. Put in another way, the tissues require more oxygen than they can receive. This leads to global tissue hypoxia, cell dysfunction, and cell death, eventually leading to multiple organ failure. The resuscitation strategy looks to restore the balance between oxygen supply and demand. This is achieved by improving cardiac preload, afterload, and contractility.
| The first goal: CVP >8 MMHG|| |
Patients with sepsis who continue to be hypotensive (or have a high lactate in excess of 4 mmol/L) despite an initial bolus of 20 mL/kg crystalloid have septic shock. They should have a central venous catheter ("central line") inserted. Their central venous pressure (CVP) should be measured and resuscitation should be commenced with fluid boluses of 500-1,500 mL every 30 min to achieve and maintain a CVP greater than 8 mmHg. Fluid boluses should be repeated as required. This can be thought of as the first goal or first resuscitation end point. Central venous catheters must be placed under strict aseptic technique and by personnel with appropriate training and skills.
| The second goal: Map >65 MMHG or systolic >90 MMHG|| |
If the CVP is greater than 8 mmHg, the patient is adequately "filled" but if the MAP is less than 65 mmHg or systolic less than 90 mmHg, the patient has septic shock. A vasopressor (a drug to constrict the blood vessels, mainly arterioles) infusion of noradrenaline should be started to maintain a MAP of at least 65 mmHg in these circumstances. The aim of this intervention, in the presence of adequate intravascular resuscitation, is to ensure adequate perfusion (blood supply) to the organs.
This can be thought of as the second goal or second resuscitation end point, aiming to keep MAP at above 65 mmHg.
| The third goal: SCVO 2 >70%|| |
Central venous oxygen saturation (ScvO 2 ) is measured by taking blood in a heparinized syringe (a normal blood gas syringe is fine) from the central venous line and the oxygen saturation is measured using the blood gas analyzer. The result will be the oxygen saturation of central venous blood or ScvO 2 . It can be considered as a surrogate for measuring the balance between oxygen delivery and demand. If low (<70%), the tissues are extracting too much oxygen from each milliliter of blood that passes. This may be due to a very high oxygen demand or too low an oxygen delivery.
IfScvO 2 is low (in practice this situation is not the norm even in septic shock) then interventions which may help include increasing the oxygen content of the blood and increasing cardiac output.
The first recommendation in the event of a low ScvO 2 is thus to transfuse the patient to achieve a hematocrit of >30% (approximating to a hemoglobin concentration of >10 g/dL).
If the patient is not anemic, or if a repeat ScvO 2 after transfusion remains low, the next strategy to redress the imbalance between oxygen delivery and demand is to increase the cardiac output to improve oxygen delivery. To enhance cardiac output, an inotropic infusion of dobutamine is started.
A dobutamine infusion is started at 2.5 μg/kg/min and increased by 2.5 μg/kg/min every 30 min until the ScvO 2 is greater than 70%, or until the maximum dose of 20 μg/kg/min is reached.
Mixed venous oxygen saturation (SvO 2 ) measured from a pulmonary artery catheter is the measurement which would most accurately reflect the imbalance between oxygen supply and demand. However, it has been shown and is widely accepted that central venous oxygen saturation (ScvO 2 ) measured from a central venous catheter gives a good approximation. 
| The surviving sepsis campaign management bundle|| |
The management bundle consists of a set of four tasks to be completed within 24 h of the onset of severe sepsis. It largely relates to critical care. It should not, however, be viewed as following the resuscitation bundle; efforts should be made to implement it concurrently. These include the following.
There is some evidence that steroids administered at physiological dosage (for example, hydrocortisone 50 mg qds) to patients that are shock-resistant to fluid resuscitation and require the administration of vasopressors are of benefit. ,,
Due to the potentially deleterious proinfective properties of these agents and a tendency to exacerbate myopathy common in critical care patients, this trial prompted the downgrading of this recommendation to level 2.
Activated protein C
Recombinant activated protein C is recommended for use in patients with severe sepsis at particularly high risk of death. A number of means to assess this risk have been used including the presence of the failure of two or more organs, refractory shock, and an Acute Physiology and Chronic Health Evaluation II (APACHE II) score (a physiological scoring system used in critical care: Acute physiology and chronic health evaluation) of >25.
However, severe sepsis and response to protein C are time-sensitive. It would be illogical to wait and watch a patient deteriorate to an arbitrarily defined physiology score before commencing potentially life-saving treatment. The SSC guidelines recommend that organizations create and follow local policies.
The coagulation cascade and inflammatory pathways play key roles in the development of multiple organ failure due to severe sepsis. Drotrecogin alpha (activated) has anti-inflammatory and antithrombotic properties and promotes fibrinolysis, which helps to explain its benefit in these patients, and also its known side-effect of bleeding occurring during infusion.
Tight glycemic control
The initial recommendation to control blood glucose arose from work by van den Berghe et al.,  in which intensive care patients randomized to receive tight glycemic control by insulin infusion (blood glucose between 80 mg/dL and 110 mg/dL) showed a statistically significant mortality reduction from 8% to 4.6%. This was, however, in a closed, predominantly cardiac surgical unit. On repeating the trial in a medical patient population, the same investigators found no outcome benefit in terms of mortality. 
It has been known for some time that ventilator-associated lung injury (VALI), a sterile inflammatory process, which can lead to fibroproliferation and permanent damage is exacerbated by barotrauma (excessive airway pressures) and cyclical volutrauma (cycling from large to small lung volumes).
The acute respiratory distress syndrome network (ARDSnet) mechanical ventilation study  demonstrated that tidal volumes during mechanical ventilation of 6 mL per kg body weight were associated with better outcomes than tidal volumes of 12 mL/kg. Other studies , have shown benefits in limiting plateau airway pressures. The recommendation within the management bundle is to limit plateau airway pressures to <30 cm H 2 0.
In practice with modern ventilators, this is relatively straightforward to achieve in many patients. Patients with more severe lung injury or with progression to acute respiratory distress syndrome (ARDS) may present more of a challenge. Strategies such as permissive hypercapnia (allowing the carbon dioxide blood tension to rise to supranormal levels through sacrificing minute ventilation for lung protection) may be of assistance as may techniques such as prone ventilation and high frequency oscillator ventilation (HFOV).
| Challenges in achieving the care bundles|| |
Never before have changes in clinical care pathways for a diverse population been intended to apply across entire hospitals globally. Challenges in achieving these goals remain challenges not only regarding the practical aspects and resource availability but also in knowledge and acceptance.
Academic debate is clearly healthy and essential in order to produce the right guidelines to ensure that they remain current, and to implement them in the right way. Debate has surrounded many aspects of the SSC recommendations and bundles. Some of the criticisms addressed to the studies underpinning the recommendations have been presented above.
A care bundle aims to achieve maximum impact by taking a list of recommendations and selecting those which are deliverable, measurable, supported by strong evidence of improving outcomes, and which are currently not used well.
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Conflicts of interest
There are no conflicts of interest.
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