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15 Sepsis andSeptic Shock
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tion, particularly during the early phase following penetrating injury, other signs such as shaking chills or rigors are more specic indicators of infection and in particular, the presence of bacteremia. Further clinical signs of infection depend on the site of infection and may range from erythema and drain­age or aspiration of pus (e.g. in surgical site infection) to cough, sputum changes and crackles on lung auscultation (such as in chest infection) to abdominal pain, guarding and rebound tenderness (e.g. in secondary peritonitis).
Although some biomarkers have been shown to perform well in differentiating between infectious and non-infectious, mostly community-acquired acute illnesses, the specicity of these laboratory investigations to identify an infection in patients following severe trauma is controversial. The trend of biomarkers such as C-reactive protein (CRP), interleukin­ 6 and procalcitonin (PCT) may, however, be used to assess the level of systemic inammation. A renewed and otherwise unexplained increase in the serum concentrations of these inammatory biomarkers, especially during the second or subsequent weeks after severe trauma, should prompt the physician to closely assess the patient for the presence of a new underlying infection. Laboratory investigations of spec­imens sampled from the site of a suspected infection (e.g. retained uid collection, cerebrospinal uid, pleural uid) may be diagnostic for selected infectious processes.
Microbiological (e.g. blood or urine cultures) and molec­ular biological (e.g. polymerase chain reaction-based tests) methods as well as imaging techniques (e.g. computer tomography) are used to conrm the presence of an underly­ing infection. Microbiological cultures with susceptibility patterns are critical to inform adequate antimicrobial ther­apy. Models to predict the risk of fungal infections such as the Candida Score combine clinical indicators with the nd-
ing of multifocal candida colonisation. Because of their high negative predictive value, they can be used to select high-risk patients for microbiological workup and biomarker sam­pling. In these patients, laboratory tests for detection of cell wall components of fungi such as the 1,3-beta--glucan test and galactomannan are useful and valuable laboratory adjuncts for the early diagnosis of posttraumatic invasive fungal infections.
15.3.2 Diagnosis ofAcute Organ Dysfunction
All patients sustaining penetrating trauma should be repeat­edly screened for the development of acute organ dysfunc­tion during their post-traumatic course. Sepsis-induced acute organ dysfunction has been dened as an acute change in the total Sequential Organ Failure Assessment score (Table15.1) of 2 points consequent to infection. A Sequential Organ Failure Assessment score count of 2 points is associated with an overall mortality risk of 10% in a general hospital population with suspected infection. Since the Sequential Organ Failure Assessment score requires the results of spe­cic laboratory investigations, simplied screening tools based on vital parameters have been suggested to assess patients for their risk of developing acute organ dysfunction from an underlying infection. Although these tools such as the quick Sequential Organ Failure Assessment score or early warning scores can predict the early mortality risk in patients with severe trauma, they have so far not been rigor­ously validated to screen trauma patients for the presence of sepsis. From a practical point of view, however, no screening tool can outperform good clinical acumen to detect new organ dysfunction. Therefore, patients following penetrating
Table 15.1 The sequential organ failure assessment score
Organ system 0 point 1 point 2 points 3 points 4 points Lungs PaO2/FiO2
(mmHg) Coagulation Platelets (G/L) Liver Bilirubin (mg/dL) <1.2 1.2–1.9 2–5.9 6–11.9 Cardiovascular
CNS Glasgow Coma
Renal Creatinine
CNS central nervous system, FiO2 fractional inspiratory oxygen concentration, MAP mean arterial blood pressure, PaO2 partial arterial oxygen pressure
a
Catecholamine doses are given as μg/kg/min for at least 1h
*
to convert creatinine mg/dL to micromol/L multiply by 88.4
a
Scale
(mg/dL)*
Urine output
(mL/d)
400
150
MAP70mmHg
15 13–14 10–12 6–9 <6
<1.2 1.2–1.9 2–3.4 3.5–4.9
<400 <300 <200 <100
<150 <100 <50 <20
MAP<70mmHg Dopamine>5
or dobutamine (any dose)
Dopamine
5.1–15 or epinephrine 0.1 or norepinephrine 0.1
<500 <200
12 Dopamine>15 or
epinephrine>0.1 or norepinephrine>0.1
5
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trauma should undergo repeated clinical assessments during their post-traumatic course. Given that, with few exceptions, acute organ dysfunctions can be diagnosed clinically, and laboratory investigations should primarily be used to conrm clinical impressions and assess whether denitions of acute organ dysfunction as indicated by an increase of the Sequential Organ Failure Assessment score of 2 points are being met.
15.4 Management Principles
Once sepsis is suspected or conrmed, timely and adequate therapeutic management is critical to facilitate survival and best possible functional recovery. A principled approach involving several elements needs to be adhered to in the management of sepsis and septic shock. Amongst main pil­lars of sepsis therapy are adequate source control, appropri­ate antimicrobial therapy and symptomatic management of acute organ dysfunction. Since sepsis outcome critically depends on the timeous nature with which it was recognised and adequate therapy initiated, early recognition and diagno­sis should be followed by prompt initiation of sepsis therapy with effective source control measures and organ support ideally occurring simultaneously. In view of the substantial mortality risk associated with sepsis and particularly septic shock, patients suffering from these conditions should be cared for in a monitored setting such as a high-dependency or intensive care unit.
The Surviving Sepsis Campaign (SSC) guideline, a joint initiative of the European Society of Intensive Care Medicine (ESICM) and the Society of Critical Care Medicine (SCCM) in the USA, provides evidence-based recommendations on the management of sepsis and septic shock. This guideline has recently been updated and the new iteration serves as a valuable resource for the management of sepsis and septic shock. Several important, helpful and benecial elements contained within this document are referred to in the subse­quent content of this chapter.
15.4.1 Treating theUnderlying Infection
As pointed out earlier, critical pillars in the management of patients with sepsis and septic shock include the important and fundamental concept of source control and antimicro- bial therapy. Important antimicrobial therapy considerations may be best addressed and covered by the terms “when, what, how, de-escalation and duration”. These elements are discussed below.
The timely administration of appropriate antimicrobial therapy is vitally important to reduce morbidity and mortal­ity from sepsis. Antimicrobial therapy should ideally begin
immediately or within the rst hour of recognition of septic shock or sepsis. Several observational studies have shown a mortality benet with each hour of early antimicrobial ther­apy administration in patients with septic shock. For patients with possible sepsis but without shock, rapid assessment of the likelihood of infection versus non-infectious illness should be undertaken. If concern for infection persists after a time-limited course of rapid investigation of the underlying aetiology, then antimicrobial therapy should be commenced within 3h from when sepsis was rst recognised. For patients with a low likelihood of infection and without shock, antimi­crobial therapy should be deferred and the patient should be closely monitored.
The initiation of antimicrobials should be directed to cover likely culprit microorganisms as well as being effec­tive at limiting superinfection and resistant microorganisms. The choice of agent(s) is based on a variety of factors and includes site of infection, patient history, details and timing of surgical procedures, previous antibiotic use, local patho­gen susceptibility patterns, immunosuppression and risk fac­tors for resistant microorganisms. Risk factors for resistance include antimicrobial exposure and acquisition of infection in a healthcare setting. Appropriate empiric coverage of the pathogens involved is particularly relevant as various studies have demonstrated a mortality reduction of approximately 50% with appropriate versus inappropriate antimicrobial choice. A vefold increase in hospital mortality was demon­strated in a 5700-patient retrospective study involving 22 dif­ferent institutions in patients with septic shock who received inappropriate antimicrobial therapy. In a study of hospital­acquired intra-abdominal infection, inadequate coverage was shown to an independent predictor of mortality. In patients with gram-negative sepsis, recent antibiotic exposure was associated with hospital mortality of 51% compared with 34% in those patients who had no recent exposure.
Relevant cultures of blood, urine, pulmonary secretions, wound drainage or other potential infection sites should be performed prior to initiation of antimicrobials, provided that obtaining the cultures does not delay antimicrobial adminis­tration. Appropriate cultures prior to initiation of antimicro­bial therapy are associated with improved outcomes. Blood cultures may be negative in as many as 50% of cases of sep­sis if empiric therapy is administered.
In general, in patients at high risk for MDR microorgan­isms, two gram-negative agents are advocated for empiric antimicrobial treatment to increase the likelihood of ade­quate coverage, while in patients with low risk for MDR microorganisms, use of a single agent for empiric treatment is deemed appropriate, as there is no compelling benet of using two agents, and the risks of antimicrobial-associated undesirable effects, Clostridioides difcile infection and the development of antimicrobial resistance are enhanced. Empiric double coverage of gram-negative bacilli is most
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important in patients at high risk for resistant microorgan­isms with severe illness, particularly septic shock.
Patients at high risk of methicillin-resistant Staphylococcus aureus (MRSA) should be considered for empiric use of agents with MRSA cover. Patient-related risk factors for MRSA include a prior history of MRSA infection or coloni­sation, recent intravenous antibiotic therapy, hemodialysis, history of recurrent skin infections or chronic wounds, pres­ence of invasive devices, recent hospital admission and severity of illness. The incidence of MRSA varies by geo­graphic region and by patient characteristics. For patients at low risk of MRSA, empiric use of antimicrobials with MRSA coverage is not advocated.
Over the past several years, there has been a signicant rise in the incidence of sepsis due to fungal organisms. Antifungal therapy should be considered in patients at high risk for such infections. Risk factors include the use of total parenteral nutrition, recent broad-spectrum antibiotics, per­forated abdominal viscus, anastomotic bowel leaks or break­down, peritoneal contamination with bowel content, immunosuppressed status or when clinical suspicion of fun­gal infection is high.
Patients should be assessed daily for opportunities to de- escalate antimicrobial therapy. This assists in limiting unnec­essary antibiotic exposure and the risk of developing resistant microorganisms. The practice is both safe and cost-effective. De-escalation involves using the narrowest spectrum antimi­crobial based on local susceptibility patterns. If the clinical course suggests that the illness is not actually due to infec­tion, the antimicrobials should be stopped. Antimicrobial de­escalation should form part of the discussion of daily rounds.
Shorter durations of antimicrobial therapy are recom- mended over longer durations. Limiting antimicrobial dura­tion to a period that is supported by prospective data also limits unnecessary antimicrobial therapy and its sequelae. The use of biomarkers such as CRP and procalcitonin (PCT) to guide antimicrobial therapy has been the subject of much debate and controversy. Clinical evaluation and acumen play a key role in determining the duration of antimicrobial administration. Biomarkers may, however, assist as a useful adjunct in helping to determine when to discontinue antimi­crobials. The decision to initiate antimicrobials is based on clinical judgement with available information. For most infections, a 5–7-day course of antimicrobial therapy is appropriate in conjunction with suitable and relevant source control. Longer courses may be required in certain circum­stances such as for Staphylococcus aureus bacteremia, endo­carditis, deep-seated bone and joint infections, fungal infections, immunocompromised hosts and if adequate source control cannot be achieved. Several well-performed prospective randomised trials now exist to guide shorter durations of antimicrobial therapy in a variety of disease pro-
cesses. In intra-abdominal infections, 4–8days of antimicro­bial therapy with suitable source control has been shown to be equivalent to any longer courses and similarly, 7–8days of treatment for ventilator-associated pneumonia.
For adults with sepsis and septic shock, the administration of beta-lactams using prolonged infusions following an ini­tial loading dose is now preferred over conventional bolus infusion. Prolonged infusions include extended infusions in which the antibiotic is infused over at least 50% of the dos­ing interval, as well as continuous infusions. Reduced short­term mortality has been demonstrated in two meta-analyses addressing prolonged infusion of beta-lactams. Additionally, antimicrobial dosing should be based on accepted pharma- cokinetic (PK) and pharmacodynamic (PD) principles and drug properties, as this is likely to result in effective and safe drug concentrations as compared to dosing provided in man­ufacturer’s product information. The utilisation of these prin­ciples and considerations, particularly in critically ill patients, is of benet in addressing such elements as aug­mented renal clearance, hypoalbuminemia, renal replace­ment therapy and extracorporeal circuits, all of which may affect the concentration of some antimicrobials (Fig.15.2). Therapeutic drug monitoring, where available, should be employed to further assist with optimal dosing of antimicrobials.
15.4.2 Source Control
Appropriate source control is a key principle and imperative in the management of sepsis and septic shock. The process may include drainage of an abscess, debridement of infected necrotic tissue, removal of infected devices including intra­vascular access devices or denitive control of a source of ongoing microbial contamination. Foci of infection readily amenable to source control include intra-abdominal abscesses and collections, gastrointestinal perforation(s), ischemic bowel, cholecystitis, obstructive uropathy associ­ated with abscess formation or pyelonephritis, necrotising soft tissue infections, other deep space infections such as empyema or septic arthritis, septic hematomas and implanted device infections. Source control should be achieved as soon as feasible following initial resuscitation and initiation of antimicrobial therapy as alluded to previously. An identied source should always be sampled and cultured for targeted therapy. Source control of infected foci has been shown to be associated with improved survival in several studies. This should ideally be achieved within a time frame not exceeding 6–12 h (preferably ≤ 6 h). Studies beyond this time frame have generally shown reduced survival. In a prospective study examining time to source control in patients with peri­tonitis and septic shock, time to initiation of surgery was
130
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Plasma antimicrobial concentrations in sepsis
Hypodynamic
circulation
Augmented
renal CL
These often coexist
Fig. 15.2 Pathophysiological changes in sepsis affecting antimicrobial concentrations
demonstrated to be an independent predictor of survival. Abdominal source control within 2h was associated with a
Leaky capillaries and/or
altered protein binding
Increased
extravascular water
Increased Vd
Low plasma
concentrations
Normal organ
function
Unchanged
Vd
Normal plasma concentrations
Vd = volume of distribution; CL = clearance
factors such as surgical or interventional staff availability may also be a factor in the ultimate decision.
98% 60-day survival as compared to no survivors in the group that waited for more than 6h for initiation of surgery. In necrotising soft tissue infections, delay in debridement
15.5 Organ Support
beyond 24h has been associated with clear effects on mortal­ity. The two most common clinical settings in which sur-
15.5.1 Fluid Therapy andHemodynamic
geons are involved in source control are in the treatment of peritonitis and soft tissue infections.
Inability to achieve adequate source control despite rapid resuscitation and initiation of appropriate antimicrobials may result in failure to obtain clinical stability or sustained patient improvement. With this consideration, prolonged efforts at medical stabilisation in lieu of source control for severely ill patients, particularly those with septic shock, are generally not advised. In general, the least invasive option that will effectively achieve source control should be pur­sued. Consideration should be given to open surgical inter­vention when other interventional approaches are inadequate or cannot be provided in a timely fashion. Surgical interven­tion may also be indicated when diagnostic uncertainty is present despite imaging studies, when success with percuta­neous procedures is uncertain and when the undesirable effects of a failed procedure are high. Institutional logistic
Hypovolemia due to endothelial dysfunction and interstitial uid accumulation is frequent in patients with sepsis. Reduced venous return results in decreased cardiac output with resultant tissue hypoperfusion and impaired oxygen delivery to organs. Restoring adequate intravascular volume status is, therefore, an essential step to secure adequate organ perfusion and oxygen supply. In view of the fact, however, that not all patients with sepsis are hypovolemic and that uid overload is as detrimental to organ function recovery and survival as hypovolemia, it is crucial to correctly identify sepsis patients in need for uid resuscitation.
The diagnosis of hypovolemia is largely based on tachy­cardia and clinical signs of peripheral hypoperfusion (e.g. cold peripheries, prolonged capillary rell time, fast and thready peripheral pulses, skin mottling) in the absence of
End organ
dysfunction (e.g.
renal or hepatic)
Decreased Vd
High plasma
concentrations
Support
Extracorporeal
circuits
Altered CL and
increased Vd of
sepsis
Plasma
concentrations
high or low
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symptoms of congestive heart failure (e.g. absence of engorged external jugular veins or ne bibasilar crackles on lung auscultation, no abdomino-jugular reux). The patho­physiological mechanisms causing oliguria in sepsis are far more complex than simple renal hypoperfusion. As a conse­quence, reduced urine output cannot be regarded as a reliable indicator of hypovolemia, particularly beyond 6–12h fol­lowing the onset of sepsis. Furthermore, it is important to underline that due to capillary leakage and loss of intravascu­lar uid into the interstitium, sepsis patients may present with clinical signs of hypovolemia despite the presence of peripheral oedema. Only in patients with clinical signs of hypovolemia should uid resuscitation be commenced. The latest SCC guideline recommends commencing with a uid bolus of 30 mL/kg within the rst 3 h of resuscitation. Although this is the average volume of uid a patient with sepsis is likely to need in order to restore intravascular vol­ume status, it appears prudent to closely re-evaluate the patient after each infusion of 500 mL and decide whether further uid loading is required or not. As there is typically a lag phase of approximately 15–30min until peripheral hypo­perfusion starts to reverse, it is valuable to adjust re­evaluation intervals to this period of time unless hypovolemic shock is present and further uid loading is clearly needed. Dynamic measures to assess uid responsiveness (prediction of the likelihood whether another uid bolus will increase stroke volume or not; e.g. stroke volume or pulse pressure variation, passive leg raise manoeuvre) can further help to inform the decision as to whether further uid boluses should be given or not. It is, however, important to remember that the primary goal of uid resuscitation is not to administer uids until the patient is no longer uid responsive, but to administer uids until peripheral perfusion is restored and lactate levels (if initially elevated) are decreasing. The SSC guideline recommends the use of balanced crystalloid solu­tions over normal saline as the rst-line uid for resuscita­tion although the recent BaSICS Trial showed no difference in 90-day mortality. Synthetic colloids such as starches and gelatins are not advocated as they may be associated with adverse effects on both renal and coagulation functions. In sepsis patients who have received large volumes of crystal­loids, albumin may be used to limit positive uid balances.
Recent data have shown that restoration of intravascular volume status will only improve capillary perfusion if uid resuscitation is initiated early after the onset of sepsis. The SSC guidelines recommend commencing uid resuscitation within 3h of diagnosing sepsis. Initiating uid resuscitation at a later stage (e.g. >48h following the onset of sepsis) is unlikely to benecially affect microcirculatory dysfunction and improve organ perfusion. This may be explained by the complex derangement of endothelial function in sepsis, including uncoupling of the macro- from the microcircula­tion in untreated or prolonged sepsis. These ndings support
the currently proposed approach of early aggressive uid resuscitation followed by a restrictive uid strategy to avoid excessive uid balances.
In case uid resuscitation does not result in restoration of adequate tissue perfusion or reversal of arterial hypotension, vasopressor drugs and ideally, invasive arterial blood pres­sure measurement are required. Norepinephrine (noradrena­line) is recommended as the rst-line vasopressor agent with an initial target of a mean arterial blood pressure of 65mmHg. To restore mean arterial blood pressure, norepinephrine should be started as early as possible. This can be initiated via a peripheral line if necessary, so that there is no delay until a central venous catheter has been secured. Based on the individual response, the mean arterial blood pressure tar­get should then be adjusted to the patient’s needs. Whereas some patients require higher mean arterial blood pressures, others will exhibit signs of adequate tissue and organ perfu­sion even when lower mean arterial blood pressures are tar­geted. Since higher doses of norepinephrine are known to cause a myriad of adverse cardiac side effects (e.g. tachycar­dia, tachyarrhythmias) in a dose-dependent fashion, particu­larly when cardiac comorbidities are present, it is recommended to add intravenous corticosteroids (e.g. 200mg of hydrocortisone per day) and consider the addition of vasopressin (where available) instead of escalating the dose of norepinephrine. Should the combination of norepi­nephrine and vasopressin not allow for adequate attainment of target blood pressure levels, the addition of epinephrine should be considered. As the mortality risk in these patients is very high, it is recommended to re-evaluate the targeted mean arterial blood pressure level necessary to allow for sur­vival. In many instances, acceptance of lower mean arterial blood pressures (e.g. 50–60mmHg) can be life-saving as this may allow for exit of the vicious circle of escalating vaso­pressor doses which then cause additional side effects further aggravating hemodynamic instability. This concept has been referred to as permissive hypotension.
In sepsis patients with signs of congestive heart failure or those in whom systemic hypoperfusion persists despite res­toration of intravascular uid status and adequate mean arte­rial blood pressures, the introduction of dobutamine or epinephrine should be considered. The use of levosimendan in patients with septic shock is discouraged because of the drug’s relevant vasodilatory side effects.
15.5.2 Ventilatory Support
In sepsis, impairment of lung function is common. This can be due to respiratory tract infection with associated alveolar damage and ventilation-perfusion mismatch, but may also occur in sepsis patients who have an extra-pulmonary infec­tious focus as a consequence of inammatory changes in the
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lungs. Similar to severe pneumonia, this can lead to diffuse alveolar damage, increases in extravascular lung water and ventilation-perfusion mismatch. Hypoxemia and reduced pulmonary compliance are frequent ndings in patients with sepsis irrespective of the underlying infection. Tachypnoea may accompany lung dysfunction but may also be a nonspe­cic sign of systemic inammation in sepsis. Taking these aspects into consideration, ventilatory support is frequently needed in patients with sepsis. The overall goals of care are to secure an oxygen saturation>90% and to avoid respira­tory decompensation due to an increased work of breathing. The SSC guidelines could not identify sufcient scientic evidence to provide guidance as to whether conservative (oxygen saturation 91–96%) or usual oxygen (oxygen satu­ration91%) targets should be applied.
Figure 15.3 summarises a pragmatic approach in keeping with current international recommendations to manage ven­tilatory dysfunction in patients with sepsis. Once a patient with sepsis develops acute respiratory distress syndrome (ARDS) and/or requires endotracheal intubation and inva­sive mechanical ventilation, it is imperative to use a low tidal volume ventilation strategy (6mL/kg ideal body weight) as this has repeatedly been shown to minimise ventilator­induced lung injury. Furthermore, the upper limit for plateau (in volume-controlled ventilation) or peak (in pressure­controlled ventilation) pressures should not exceed 30 cmH2O. In patients with moderate or severe sepsis­induced ARDS, it is recommended that a higher positive end-expiratory pressure (PEEP) strategy is preferred over a lower one and that traditional (instead of incremental PEEP titration) recruitment manoeuvres are used when lung de­recruitment is suspected. In addition, mechanical ventilation in the prone position for >12h daily and intermittent use of neuromuscular blocking agents are recommended in these patients too. When conventional mechanical ventilation fails to provide adequate ventilatory support, the use of veno­venous extracorporeal membrane oxygenation should be considered in experienced centres with the infrastructure in place to support its use.
mobilisation. Elements pertaining to mechanical ventilation and use of corticosteroids have already been alluded to earlier.
Renal Replacement Therapy
Septic shock is the most common cause of acute kidney injury (AKI) in the intensive care unit (ICU) accounting for approximately half of all AKIs and is associated with the highest mortality. Renal replacement therapy may be indi­cated for the treatment of uremia, uid overload and meta­bolic derangement such as hyperkalemia and metabolic acidosis. Early use of renal replacement therapy is theoreti­cally attractive as it may limit organ injury and uid over­load, as well as remove inammatory mediators responsible for the clinical manifestations of sepsis.
Venous Thromboembolism (VTE) Prophylaxis
Pharmacological prophylaxis using unfractionated heparin (UFH) or low-molecular-weight heparin (LMWH) is recom­mended in the absence of contraindications to the use of these agents. LMWH is recommended over UFH in patients with no contraindications to LMWH, assuming availability of both medications. Non-pharmacological prophylaxis includes graduated compression stockings (GCS), intermit­tent pneumatic compression (IPC) devices and passive and early mobilisation where appropriate. GCS and IPC devices may be used in the setting where contraindications to the use of pharmacologic prophylaxis exist and in high-risk patients for VTE.
Glucose Control
Blood glucose should be managed using a protocolised approach, commencing when blood glucose levels are >10mmol/L (180mg/dL), with a target blood glucose value of 10mmol/L (180mg/dL) aiming to keep the blood glu­cose in the range of 6–10mmol/L (108–180mg/dL) to avoid detrimental hypoglycemia. Measurements should be con­ducted every 1–2h until values and insulin infusion rates stabilise and then every 4h thereafter in patients receiving insulin infusions.
15.5.3 General Interventions
15.5.3.1 Other Supportive Therapies inPatients
withSepsis andSeptic Shock
Additional supportive therapies for patients with sepsis and septic shock are closely aligned with the general manage­ment of critically ill patients (Table15.2) and include such elements as renal replacement therapy, nutrition, glycemic control, venous thromboembolism prophylaxis, sedation and analgesia, use of neuromuscular blocking agents, stress ulcer prophylaxis, red blood cell transfusion, positioning and early
Sedation andAnalgesia
Continuous or intermittent sedation should be minimised in mechanically ventilated patients targeting specic titration end points from sedation scales. Common approaches include implementation of nurse-directed protocols, admin­istration of intermittent sedation and daily sedation interrup­tion. Short-acting sedatives including propofol and dexmedetomidine may result in improved outcomes.
Adequate pain control should be attained in all patients where necessary (analgesia-rst sedation), and lighter seda­tion targets aimed for in general.
Hypoxemic
Venlatory Respiratory Failure
CV
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no
Respiratory Failure
(SaO2≤90%)
Standard
Oxygen Therapy
CV
normalWOB
+no respiratory acidosis
yes
SaO2≤90%
ja
(increased WOB or acute respiratory acidosis)
±Hypoxemic Respiratory Failure
Non-Invasive Venlaon
no
CV
High Flow Nasal
Oxygen Therapy
CV
no
relevantly increased WOB,
severe respiratory acidosis or SaO
≤90%
yes
2
Invasive Mechanical Venlaon
CV
Fig. 15.3 Therapeutic approach to patients with sepsis-induced acute respiratory failure. SaO2, arterial oxygen saturation; WOB, work of breath- ing. Icons by Flaticom.com
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M. Mer and M. W. Dünser
Table 15.2 Core elements of general supportive care in patients with sepsis and septic shock
Intervention Comment Mechanical
ventilation
Renal replacement therapy
Nutrition Commence enteral feeding early Glucose control Maintain blood glucose < 10mmol/L
Venous thromboembolism prophylaxis
Blood transfusion If hemoglobin level <7.0g/dL (70g/L) in
Sedation and analgesia
Neuromuscular blocking agents
Stress ulcer prophylaxis
Corticosteroids Consider in patients with septic shock and
Positioning and mobilisation
Psychological support
UFH unfractionated heparin, LMWH low-molecular-weight heparin, ARDS acute respiratory distress syndrome, GI gastrointestinal
Lung protective ventilation strategy. Includes tidal volume 6mL/kg ideal body weight, plateau airway pressures 30cmH2O
As may be indicated for uid overload, metabolic derangement (severe uremia, hyperkalemia, acidosis)
(180mg/dL) UFH or LMWH (LMWH preferred);
mechanical prophylaxis, e.g. pneumatic compressive devices in select cases or where contraindications to pharmacologic prophylaxis exist; continue until patient fully mobile
stable non-bleeding patients Adequate pain control in all patients where
required and minimise sedation In setting of respiratory dyssynchrony to
facilitate mechanical ventilation in patients with moderate-severe ARDS
In patients with risk factors for GI bleeding
an ongoing requirement for vasopressor support where adequate uid resuscitation has occurred. Typical dose– hydrocortisone 200mg/day given as 50mg every 6 h intravenously or as a continuous infusion
Elevate head of bed 30–45° in mechanically ventilated patients; meticulous pressure area care-document; active early mobilisation
Ongoing patient encouragement where feasible and constructive and meaningful family interaction
Use ofNeuromuscular Blocking Agents
Neuromuscular blocking agents may be considered in mechanically ventilated septic patients with moderate-severe acute respiratory distress syndrome (ARDS) in the setting of respiratory dyssynchrony and to facilitate mechanical venti­lation. These agents may improve chest wall compliance, prevent dyssynchrony and reduce peak airway pressures. Intermittent neuromuscular blockade boluses are preferred to continuous infusions.
Nutrition
Early enteral feeding should be commenced in patients who can tolerate it within 48h provided that they are adequately resuscitated and hemodynamically stable. Either trophic/
hypocaloric or full enteral feeding strategies may be employed. If trophic/hypocaloric feeding is the initial strat­egy, then feeds should be advanced according to patient tol­erance to reach feeding goals. If enteral feeding is not fully established within a week, parenteral supplementation should be considered. A feeding protocol is useful to opti­mise delivery of enteral nutrition.
Stress Ulcer Prophylaxis
Stress ulcer and septic shock prophylaxis is recommended in patients with sepsis and septic shock who have risk factors for gastrointestinal (GI) bleeding. Risk factors for GI bleed­ing include mechanical ventilation 48 h, coagulopathy, renal replacement therapy, liver disease, multiple comorbidi­ties, and higher organ failure scores.
Red Blood Cell (RBC) Transfusion
Use of a restrictive over liberal transfusion policy is recom­mended in patients who have been fully and adequately resuscitated and where there is no ongoing bleeding. A restrictive transfusion strategy typically includes a hemoglo­bin concentration transfusion trigger of 7 g/dL (70 g/L). RBC transfusion however should not be guided by hemoglo­bin concentration alone. Assessment of the overall clinical status of a patient and consideration of various circumstances such as acute myocardial ischemia severe hypoxemia, or acute hemorrhage, is required.
Positioning andEarly Mobilisation
This includes elevating the head of the bed to between 30 and 45 degrees for mechanically ventilated patients and regular meticulous pressure area care. Active and early mobilisation should commence as soon as the patient is stable enough to participate. This assists in improving both mobility status and muscle strength. The role of physiotherapists is hugely relevant.
Based on currently available evidence, the SSC guideline specically recommends against the use of certain therapies and interventions (Table15.3).
Table 15.3 Therapies of the Surviving Sepsis Campaign guidelines recommends against using in patients with sepsis
• Polymyxin B hemoperfusion
• Intravenous immunoglobulins
• Renal replacement in patients without denitive indications for renal replacement therapy
• Intravenous vitamin C
• Sodium bicarbonate therapy to improve hemodynamics or to reduce vasopressor requirements in patients with septic shock and hypoperfusion-induced lactic acidosis
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15.6 Transition ofCare
Following recovery from sepsis, the transition from the intensive care unit to the normal ward is both an important step in the psychological healing process of the patient (mov­ing forward and not being dependent on life support any lon­ger), but also a critical one exposing the patient to certain risks, including respiratory and infectious complications. Respiratory complications often arise as a consequence of less intense physical and respiratory therapy outside of the intensive care unit. In addition, dysphagia as a result of pro­longed endotracheal intubation or tracheostomy is well known to make post-intensive care unit patients particularly vulnerable to respiratory complications including pulmonary infections. Due to the compensatory anti-inammatory response to both trauma and sepsis, patients recovering from these conditions are considered immunosuppressed and spe­cically prone to acquire further infections and septic epi­sodes. Despite being associated with very high mortality rates, recurrent septic episodes tend to occur in a fashion that is less acute and fulminant than the rst septic episode. This may put patients at high risk as the acuity and severity of recurrent sepsis may not be as overt or obvious and thus may be overlooked, with adequate management and early read­mission to an intensive care or high dependency unit being delayed.
It is, therefore, critical to identify the correct time point to transition care from an intensive to a non-intensive care set­ting and to prepare this step as best as possible. Although the optimum time to transfer a patient from the intensive care unit to a normal ward may depend on several institutional factors (including the availability of step-down or high dependency unit), the patient should be free of the need for organ support and stable for an adequate time period. Experience indicates that the longer the period of organ dysfunction has lasted, the longer this observational phase without need for organ sup­port should be (e.g. up to 48–72h in patients with prolonged critical illness). In selected patients, transition from an inten­sive to a non-intensive care setting may not only depend on the absence of organ dysfunction but also on the need for intensive nursing care or physical therapy (e.g. patients with high spinal cord injuries and reduced consciousness or those with critical illness acquired weakness). In order to make the transition process as safe as possible for the patient, the use of structured hand over processes from the intensive care unit to the ward is advocated. In addition, reconciliation of medica­tions at intensive care unit discharge as well as close follow­up during the rst days following discharge from the intensive care unit is recommended.
While respiratory and infectious complications pose immediate threats to patients recovering from sepsis, critical illness due to sepsis is associated with multiple long-term sequelae. These include, but are not limited to, reduced func-
tionality including pulmonary capacities, cognitive impair­ment and post-traumatic stress disorders. Furthermore, recent research has indicated that patients following an over­whelming pro-inammatory stimulus such as sepsis, exhibit increased levels of pro-inammatory mediators that last for weeks to months. This prolonged sub-clinical inammation is the likely explanation for the increased risk of cardiovas­cular events during the rst year following a septic episode. Early inclusion of sepsis survivors into rehabilitation programs as well as screening for economic, social and reli­gious support is currently recommended by the SSC guidelines.
15.7 Prevention ofPost-traumatic Sepsis
Prevention of post-traumatic sepsis mainly focusses on infection prevention. Since the pathogenesis of the dysregu­lated host response to infection resulting in sepsis is so far only poorly understood, no current strategy exists to prevent development of sepsis in patients acquiring an acute infec­tion. Although the concept of timely recognition and ade­quate management of infection appears biologically sound, it has not been proven that this can signicantly reduce the occurrence of sepsis.
Infection prevention in patients with penetrating trauma includes both prevention of wound infections and preven­tion of hospital-acquired infectious complications. The key steps to prevent deep and supercial wound infections fol­lowing penetrating trauma are optimal early (<6h) surgical wound care including aseptic techniques, disinfection, (high pressure) irrigation, debridement, appropriate timing of wound closure and negative pressure wound therapy as well as antibiotic prophylaxis. The efcacy of antibiotics to prevent infections in patients with penetrating injuries depends on several factors. Of particular relevance is appro­priate timing. Data have shown that antibiotic prophylaxis should be administered to patients with penetrating wounds to deep tissue structures as early as possible, preferably within the rst hour following injury. Antibiotic prophy­laxis delivered only during or even after surgery is signi­cantly less effective to decrease the rate of wound infections. Additionally, the choice of antibiotics depends on the injury site and contamination of underlying tissues. Furthermore, as prolonged duration of antibiotic prophylaxis has been shown to paradoxically increase the risk of subsequent infections, the duration of antibiotic prophylaxis in patients with penetrating injuries should not in general exceed sug­gested time frames (24h). In general, a single dose of pro­phylactic antimicrobial(s) is often all that is required unless there is signicant blood loss or the patient is subjected to prolonged surgery, in which case repeat dosing is indicated.
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after touching a patient’s surroundings
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Fig. 15.4 The ve moments of hand hygiene. Adapted from the World Health Organization. Icons by
Flaticom.com
M. Mer and M. W. Dünser
before a procedure
before touching a patient
after a procedure or body fluid
exposure risk
after touching a patient
Prevention of hospital-acquired infectious complications largely relies on strict hand hygiene (Fig.15.4). Dedicated bun­dles and protocols have been shown to decrease or even elimi­nate the risk of hospital-/ventilator-acquired pneumonia and central line-associated bloodstream infections, respectively. Consistent removal of urinary or central venous catheters and wound drains when they are no longer needed is another impor­tant step to prevent device-related infections. Therapeutic strat­egies to hasten recovery from critical illness such as targeted sedation, early mobilisation and adequate nutritional support are strategies to reduce the risk of post-traumatic infections. These elements have been addressed earlier.
Finally, vaccinations are highly effective in preventing late infections and fulminant sepsis (e.g. the overwhelming post-splenectomy infection syndrome) in patients following splenectomy. Vaccinations are recommended to be adminis­tered at 14days after trauma or prior to hospital discharge, whichever comes rst. Important exceptions include patients who require ongoing organ support or those undergoing major surgical procedures, as their immune systems may not sufciently respond to vaccination. In-hospital vaccination is recommended to include the pneumococcal 13-valent conju­gate, Haemophilus inuenzae type b (Hib), quadrivalent meningococcal and meningococcal serogroup B vaccines. It is safe to administer all vaccinations at the same time either as compound vaccines or using different injection sites. Importantly, the patient must be informed on the need to receive another dose of the pneumococcal 23-polysaccha­ride, quadrivalent meningococcal and meningococcal sero­group B vaccines 2months later, as well as further doses of the pneumococcal 23-polysaccharide and quadrivalent
meningococcal vaccine every 5years, and the seasonal inu­enza vaccine annually.
15.8 Conclusions
This chapter outlines the essentials and most current concepts and understanding of the relevant epidemiology, denitions, pathogenesis, diagnosis and investigation, and management principles of patients with sepsis and septic shock in a pragmatic and evidence-based fashion, and as may be pertinent to patients with penetrating trauma. Sepsis and septic shock are common and should be regarded as medical emergencies. Patients with penetrating trauma are at high risk for the development of sepsis and its associated sequelae. Early recognition, focussed uid administration and hemodynamic support, source control, and appropriate antimicrobial therapy are the cornerstones that offer the best possible survival outcomes for patients suffering from sepsis and septic shock. Appropriate supportive measures and post-sepsis care are important and integral components of care that further enhance outcomes. Adherence to these principles which are based on current best practice, is key to reducing the burden of resulting disease, death, and disability from sepsis and septic shock in patients with penetrating trauma.
Key Messages
• Sepsis and septic shock are common syndromes of immense clinical importance.
• Sepsis is a life-threatening organ dysfunction due to a dysregulated host response to infection.