Intensive care medicine deals with the critically ill; these patients usually have multiple organ failure, and complex medical conditions. The mortality in Australia and New Zealand among this population is approximately 16.1%, with approximately 24.2% having existing co-morbidities, and 23.4% of these patients experiencing sepsis or septic shock. Sepsis is a clinical syndrome that traditionally was regarded as a physiological maladaptive response to a foreign pathogen and ranges in disease severity from simple sepsis to septic shock, a life threatening condition, associated with multiple organ failure. Sepsis has profound effects on all systems of the body, and most notably the cardiovascular, renal and hepatic systems. There has been much research into the septic critically ill patient and recent developments in basic pharmacology and physiology has yielded results applicable to clinical practice. Sepsis may induce a state of increased cardiac output, which has significant effects on drug pharmacokinetics and pharmacodynamics. This increased cardiac output increases both renal and hepatic blood flow, and alters rates of antibiotic metabolism, and excretion. There are also alterations in the fluid compartments of the septic critically ill, that results in an altered volume of distribution, and ultimately decreased antibiotic concentrations at their site of action. This article will examine and review in detail the septic critically ill patient, and the effects that sepsis has on physiology and the resulting altered antibiotic pharmacokinetics and pharmacodynamics. Current knowledge suggests that the medical prescriber should be weary of antibiotic dosing in the septic critically ill, and consider alternative dosing regimes that are individualized to the patient in order to maximize efficacy. Show
Keywords: Critical care, sepsis, physiology, multiple organ, physiological maladaptive response, antibiotic dosing, antibiotic pharmacokinetics, cardiovascular, organ systems, proinflammatory mediators, immune-propagation, hydrophilic antimicrobial agents, preexisting cardiac disease, host immune system, vasoactive medications Sepsis and septic shock are medical emergencies and must be treated immediately. It's likely you'll be admitted to an intensive care unit (ICU) for urgent treatment and to carefully monitor your progress. In some cases treatment may begin in the emergency department. Oxygen therapyTo help you breathe more easily, you'll be given oxygen through a face mask, a tube inserted into your nose, or an endotracheal tube inserted into your mouth. If you have severe shortness of breath, a mechanical ventilator may be used. Increasing blood flowYou'll probably be given fluids directly into a vein. This will help raise your blood pressure by increasing the amount of fluid in your blood. To increase the blood flow to your vital organs, such as your brain, liver, kidneys and heart, you may be prescribed inotropic medicines or vasopressors. Inotropic medicinesInotropic medicines (inotropes), such as dobutamine, stimulate your heart. They increase the strength of your heartbeat, which helps get oxygen-rich blood to your tissues and organs, where it's needed. VasopressorsVasopressors include:
These medicines will cause your blood vessels to narrow, increasing your blood pressure and the flow of blood around your body. This will allow your vital organs to start functioning properly. AntibioticsAntibiotics are often used to treat the associated bacterial infection. The type of antibiotic used depends on the type of bacterial infection and where in the body the infection started. You may be started on antibiotics immediately to increase your chances of survival. Initially, two or three types of antibiotics may be used. The most effective type of antibiotic can be used once the bacterium responsible for the infection is identified. SurgeryIn severe cases of sepsis or septic shock, the large decrease in blood pressure and blood flow can kill organ tissue. If this happens, surgery may be required to remove the dead tissue. HistorySepsis or septic shock is systemic inflammatory response syndrome (SIRS) secondary to a documented infection (see Shock Classification, Terminology, and Staging). Detrimental host responses to infection occupy a continuum that ranges from sepsis to septic shock and multiple organ dysfunction syndrome (MODS). The specific clinical features depend on where the patient falls on that continuum. Symptoms of sepsis are often nonspecific and include the following:
These symptoms are not pathognomonic for sepsis syndromes and may be present in a wide variety of other conditions. Alternatively, typical symptoms of systemic inflammation may be absent in sepsis, especially in elderly individuals. In sepsis, symptoms may include decreased urine output and cyanosis (blueish discoloration of the lips and/or digits). Fever is a common symptom, though it may be absent in elderly or immunosuppressed patients. The hypothalamus resets in sepsis, so that heat production and heat loss are balanced in favor of a higher temperature. An inquiry should be made about fever onset (abrupt or gradual), duration, and maximal temperature. These features have been associated with increased infectious burden and severity of illness. However, fever alone is an insensitive indicator of sepsis; in fact, hypothermia is more predictive of illness severity and death. Chills are a secondary symptom associated with fever, developing as a consequence of increased muscular activity that produces heat and raises the body temperature. Sweating occurs when the hypothalamus returns to its normal set point and senses the higher body temperature, stimulating perspiration to evaporate excess body heat. Mental function is often altered. Mild disorientation or confusion is especially common in elderly individuals. Apprehension, anxiety, agitation, and, eventually, coma are manifestations of sepsis. The exact cause of metabolic encephalopathy is not known; altered amino acid metabolism may play a role. Hyperventilation with respiratory alkalosis is a common feature of patients with sepsis. This feature results from stimulation of the medullary respiratory center by endotoxins and other inflammatory mediators. Localizing symptoms referable to organ systems may provide useful clues to the etiology of sepsis. Such symptoms include the following:
Physical ExaminationThe hallmarks of sepsis and septic shock are changes that occur at the microvascular and cellular level with diffuse activation of inflammatory and coagulation cascades, vasodilation and vascular maldistribution, capillary endothelial leakage, and dysfunctional utilization of oxygen and nutrients at the cellular level. The challenge for clinicians is to recognize that this process is under way when it may not be clearly manifested in the vital signs or clinical examination. The physical examination should first involve assessment of the patient’s general condition, including an assessment of airway, breathing, and circulation (ie, the ABCs), as well as mental status. An acutely ill, flushed, and toxic appearance is observed universally in patients with serious infections. Examine vital signs, and observe for signs of hypoperfusion. Carefully examine the patient for evidence of localized infection. Ensure that the patient’s body temperature is measured accurately. Rectal temperatures should be obtained, as oral and tympanic temperatures are not always reliable. Fever may be absent, but patients generally have tachypnea and tachycardia. Pay attention to the patient’s skin color and temperature. Pallor or grayish or mottled skin are signs of poor tissue perfusion seen in septic shock. In the early stages of sepsis, cardiac output is well maintained or even increased. The vasodilation may result in warm skin, warm extremities, and normal capillary refill (warm shock). As sepsis progresses, stroke volume and cardiac output fall. The patients begin to manifest the signs of poor perfusion, including cool skin, cool extremities, and delayed capillary refill (cold shock). In sepsis, symptoms may include decreased urine output and cyanosis (blueish discoloration of the lips and/or digits). Petechiae or purpura (see the image below) can be associated with disseminated intravascular coagulation (DIC). These findings are an ominous sign.  Tachycardia is a common feature of sepsis and indicative of a systemic response to stress; it is the physiologic mechanism by which cardiac output, and thus oxygen delivery to tissues, is increased. Tachycardia indicates hypovolemia and the need for intravascular fluid repletion; however, an increased heart rate often persists in sepsis despite adequate fluid repletion. Narrow pulse pressure and tachycardia are considered the earliest signs of shock. Tachycardia may also be a result of fever itself. Tachypnea is a common and often underappreciated feature of sepsis. It is an indicator of pulmonary dysfunction and is commonly found in pneumonia and acute respiratory distress syndrome (ARDS), both of which are associated with increased mortality in sepsis. Stimulation of the medullary ventilatory center by endotoxins and other inflammatory mediators is a possible cause. As tissue hypoperfusion ensues, the respiratory rate also rises to compensate for metabolic acidosis. The patient often feels short of breath or appears mildly anxious. Altered mental status is another common feature of sepsis. It is considered a sign of organ dysfunction and is associated with increased mortality. Mild disorientation or confusion is especially common in elderly individuals. Other manifestations include apprehension, anxiety, and agitation. Profound cases may involve obtundation or comatose states. The cause of these mental status abnormalities is not entirely understood, but in addition to cerebral hypoperfusion, altered amino acid metabolism has been proposed as a causative factor. In septic shock, it is important to identify any potential source of infection. This is particularly important in cases where a site of infection can be removed or drained, as in certain intra-abdominal infections, soft-tissue abscesses and fasciitis, or perirectal abscesses. The following physical signs help localize the source of an infection:
ComplicationsEnd-organ failure is a major contributor to mortality in sepsis and septic shock. The complications with the greatest adverse effect on survival are ARDS, DIC, and acute kidney injury (AKI; previously termed acute renal failure [ARF]). Acute respiratory distress syndromeAcute lung injury (ALI)—mild ARDS, by the Berlin Definition [10] —leading to moderate or severe ARDS is a major complication of sepsis and septic shock. The incidence of ARDS is approximately 18% in patients with septic shock, and mortality approaches 50%. ARDS also leads to prolonged intensive care unit (ICU) stays and an increased incidence of ventilator-associated pneumonia. ARDS secondary to sepsis demonstrates the manifestations of underlying sepsis and the associated multiple organ dysfunction. Pulmonary manifestations include acute respiratory distress and acute respiratory failure resulting from severe hypoxemia caused by intrapulmonary shunting. Fever and leukocytosis may be present secondary to the lung inflammation. The severity of ARDS may range from mild lung injury to severe respiratory failure. The onset of ARDS usually is within 12-48 hours of the inciting event. The patients demonstrate severe dyspnea at rest, tachypnea, and hypoxemia; anxiety and agitation are also present. The frequency of ARDS in sepsis has been reported to range from 18% to 38% (with gram-negative sepsis, 18-25%). Sepsis and multiorgan failure are the most common cause of death in ARDS patients. Approximately 16% of patients with ARDS die of irreversible respiratory failure. Most patients who show improvement achieve maximal recovery by 6 months, with lung function improving to 80-90% of predicted values. Acute kidney injurySepsis is the most common cause of AKI (ARF), which affects 40-70% of all critically ill patients, depending on how AKI is defined (eg, according to the RIFLE [risk, injury, failure, loss, and end stage] or AKIN [Acute Kidney Injury Network] classifications]). [43] AKI complicates therapy and worsens the overall outcome. [53] There is an increased risk of mortality when urosepsis is present with sepsis and septic shock [54] ; however, the global prognosis for patients with urosepsis is better than that for those with sepsis from other infectious sites. Other complications in septic shockOther complications include the following:
Author Andre Kalil, MD, MPH Professor of Medicine, Department of Medicine, Section of Infectious Diseases, University of Nebraska College of Medicine; Director, Transplant ID Program, University of Nebraska Medical Center Disclosure: Nothing to disclose. Coauthor(s) Chief Editor Michael R Pinsky, MD, CM, Dr(HC), FCCP, FAPS, MCCM Professor of Critical Care Medicine, Bioengineering, Cardiovascular Disease, Clinical and Translational Science and Anesthesiology, Vice-Chair of Academic Affairs, Department of Critical Care Medicine, University of Pittsburgh Medical Center, University of Pittsburgh School of Medicine Michael R Pinsky, MD, CM, Dr(HC), FCCP, FAPS, MCCM is a member of the following medical societies: American College of Chest Physicians, American College of Critical Care Medicine, American Thoracic Society, European Society of Intensive Care Medicine, Society of Critical Care Medicine Disclosure: Received income in an amount equal to or greater than $250 from: Baxter Medical, Exostat, LiDCO<br/>Received honoraria from LiDCO Ltd for consulting; Received intellectual property rights from iNTELOMED. Acknowledgements Fatima Al Faresi, MD Dermatologist, Tawam Hospital, Al Ain, UAE Disclosure: Nothing to disclose. Barry E Brenner, MD, PhD, FACEP Professor of Emergency Medicine, Professor of Internal Medicine, Program Director, Emergency Medicine, Case Medical Center, University Hospitals, Case Western Reserve University School of Medicine Barry E Brenner, MD, PhD, FACEP is a member of the following medical societies: Alpha Omega Alpha, American Academy of Emergency Medicine, American College of Chest Physicians, American College of Emergency Physicians, American College of Physicians, American Heart Association, American Thoracic Society, Arkansas Medical Society, New York Academy of Medicine, New York Academy ofSciences,and Society for Academic Emergency Medicine Disclosure: Nothing to disclose. John L Brusch, MD, FACP Assistant Professor of Medicine, Harvard Medical School; Consulting Staff, Department of Medicine and Infectious Disease Service, Cambridge Health Alliance John L Brusch, MD, FACP is a member of the following medical societies: American College of Physicians and Infectious Diseases Society of America Disclosure: Nothing to disclose. Ismail Cinel, MD, PhD Visiting Associate Professor, Division of Critical Care Medicine, Robert Wood Johnson Medical School, University of Medicine and Dentistry of New Jersey Disclosure: Nothing to disclose. Clara-Dina Cokonis, MD Staff Physician, Department of Medicine, Division of Dermatology, Cooper Hospital University Medical Center Disclosure: Nothing to disclose. R Phillip Dellinger, MD Professor of Medicine, Program Director, Critical Care Medicine Fellowship Program, Robert Wood Johnson School of Medicine, University of Medicine and Dentistry of New Jersey; Head, Division of Critical Care Medicine, Medical Director, Medical/Surgical/Cardiovascular Surgical Intensive Care Unit, Cooper University Hospital Disclosure: Wyeth Consulting fee Consulting; BRAHMS Grant/research funds Other Clinical Trial; Artisan Grant/research funds Other Clinical Trial; Agenix Grant/research funds Other Clinical Trial Daniel J Dire, MD, FACEP, FAAP, FAAEM Clinical Professor, Department of Emergency Medicine, University of Texas Medical School at Houston; Clinical Professor, Department of Pediatrics, University of Texas Health Sciences Center San Antonio Daniel J Dire, MD, FACEP, FAAP, FAAEM is a member of the following medical societies: American Academy of Clinical Toxicology, American Academy of Emergency Medicine, American Academy of Pediatrics, American College of Emergency Physicians, and Association of Military Surgeons of the US Disclosure: Nothing to disclose. Dirk M Elston, MD Director, Ackerman Academy of Dermatopathology, New York Dirk M Elston, MD is a member of the following medical societies: American Academy of Dermatology Disclosure: Nothing to disclose. Michael R Filbin, MD Clinical Instructor, Department of Emergency Medicine, Massachusetts General Hospital Michael R Filbin, MD is a member of the following medical societies: American College of Emergency Physicians, Massachusetts Medical Society, and Society for Academic Emergency Medicine Disclosure: Nothing to disclose. Franklin Flowers, MD Chief, Division of Dermatology, Professor, Department of Medicine and Otolaryngology, Affiliate Associate Professor of Pediatrics and Pathology, University of Florida College of Medicine Franklin Flowers, MD, is a member of the following medical societies: American College of Mohs Micrographic Surgery and Cutaneous Oncology Disclosure: Nothing to disclose. Cory Franklin, MD Professor, Department of Medicine, Rosalind Franklin University of Medicine and Science; Director, Division of Critical Care Medicine, Cook County Hospital Cory Franklin, MD is a member of the following medical societies: New York Academy of Sciences and Society of Critical Care Medicine Disclosure: Nothing to disclose. Theodore J Gaeta, DO, MPH, FACEP Clinical Associate Professor, Department of Emergency Medicine, Weill Cornell Medical College; Vice Chairman and Program Director of Emergency Medicine Residency Program, Department of Emergency Medicine, New York Methodist Hospital; Academic Chair, Adjunct Professor, Department of Emergency Medicine, St George's University School of Medicine Theodore J Gaeta, DO, MPH, FACEP is a member of the following medical societies: Alliance for Clinical Education, American College of Emergency Physicians, Clerkship Directors in Emergency Medicine, Council of Emergency Medicine Residency Directors, New York Academy of Medicine, and Society for Academic Emergency Medicine Disclosure: Nothing to disclose. Hassan I Galadari, MD Assistant Professor of Dermatology, Faculty of Medicine and Health Sciences, United Arab Emirates University Hassan I Galadari, MD is a member of the following medical societies: American Academy of Dermatology, American Medical Association, American Medical Student Association/Foundation, and American Society for Dermatologic Surgery Disclosure: Nothing to disclose. William D James, MD Paul R Gross Professor of Dermatology, Vice-Chairman, Residency Program Director, Department of Dermatology, University of Pennsylvania School of Medicine William D James, MD is a member of the following medical societies: American Academy of Dermatology and Society for Investigative Dermatology Disclosure: Elsevier Royalty Other Paul Krusinski, MD Director of Dermatology, Fletcher Allen Health Care; Professor, Department of Internal Medicine, University of Vermont College of Medicine Paul Krusinski, MD is a member of the following medical societies: American Academy of Dermatology, American College of Physicians, and Society for Investigative Dermatology Disclosure: Nothing to disclose. Steven M Manders, MD Clinical Assistant Professor, Department of Dermatology, University of Pennsylvania; Associate Professor, Department of Internal Medicine, Division of Dermatology, University of Medicine and Dentistry of New Jersey Disclosure: Nothing to disclose. Steven Mink, MD Head, Section of Pulmonary Medicine, Department of Internal Medicine, St Boniface Hospital; Professor of Medicine, University of Manitoba, Canada Steven Mink, MD is a member of the following medical societies: Alpha Omega Alpha Disclosure: Nothing to disclose. Mark L Plaster, MD, JD Executive Editor, Emergency Physicians Monthly Mark L Plaster, MD, JD is a member of the following medical societies: American Academy of Emergency Medicine and American College of Emergency Physicians Disclosure: M L Plaster Publishing Co LLC Ownership interest Management position Sat Sharma, MD, FRCPC Professor and Head, Division of Pulmonary Medicine, Department of Internal Medicine, University of Manitoba; Site Director, Respiratory Medicine, St Boniface General Hospital Sat Sharma, MD, FRCPC is a member of the following medical societies: American Academy of Sleep Medicine, American College of Chest Physicians, American College of Physicians-American Society of Internal Medicine, American Thoracic Society, Canadian Medical Association, Royal College of Physicians and Surgeons of Canada, Royal Society of Medicine, Society of Critical Care Medicine, and World Medical Association Disclosure: Nothing to disclose. Francisco Talavera, PharmD, PhD Adjunct Assistant Professor, University of Nebraska Medical Center College of Pharmacy; Editor-in-Chief, Medscape Drug Reference Disclosure: Medscape Salary Employment Vicken Y Totten, MD, MS, FACEP, FAAFP Assistant Professor, Case Western Reserve University School of Medicine; Director of Research, Department of Emergency Medicine, University Hospitals, Case Medical Center Vicken Y Totten, MD, MS, FACEP, FAAFP is a member of the following medical societies: American College of Emergency Physicians and Society for Academic Emergency Medicine Disclosure: Nothing to disclose. Richard P Vinson, MD Assistant Clinical Professor, Department of Dermatology, Texas Tech University Health Sciences Center, Paul L Foster School of Medicine; Consulting Staff, Mountain View Dermatology, PA Richard P Vinson, MD is a member of the following medical societies: American Academy of Dermatology, Association of Military Dermatologists, Texas Dermatological Society, and Texas Medical Association Disclosure: Nothing to disclose. Eric L Weiss, MD, DTM&H Medical Director, Office of Service Continuity and Disaster Planning, Fellowship Director, Stanford University Medical Center Disaster Medicine Fellowship, Chairman, SUMC and LPCH Bioterrorism and Emergency Preparedness Task Force, Clinical Associate Progressor, Department of Surgery (Emergency Medicine), Stanford University Medical Center Eric L Weiss, MD, DTM&H is a member of the following medical societies: American College of Emergency Physicians, American College of Occupational and Environmental Medicine, American Medical Association, American Society of Tropical Medicine and Hygiene, Physicians for Social Responsibility, Southeastern Surgical Congress, Southern Association for Oncology, Southern Clinical Neurological Society, and Wilderness Medical Society Disclosure: Nothing to disclose. What are the pathophysiological changes associated with septic shock?Septic shock can lead to renal dysfunction, which can range from mild proteinuria to anuria and profound renal failure. Hypovolemia, renal vasoconstriction, hypotension, and nephrotoxic agents are the mechanisms by which acute kidney injury occurs.
Which physiological changes are seen in a patient with prolonged sepsis?With sepsis, patients typically have fever, tachycardia, diaphoresis, and tachypnea; blood pressure remains normal. Other signs of the causative infection may be present. As sepsis worsens or septic shock develops, an early sign, particularly in older people or the very young, may be confusion or decreased alertness.
What is the physiological response to sepsis?Sepsis results when an infectious insult triggers a localized inflammatory reaction that then spills over to cause systemic symptoms of fever or hypothermia, tachycardia, tachypnea, and either leukocytosis or leukopenia. These clinical symptoms are called the systemic inflammatory response syndrome.
Which of the following are the 3 effects of septic shock?Complications of septic shock can include: inability of the lungs to take in enough oxygen (respiratory failure) the heart not being able to pump enough blood around the body (heart failure) kidney failure or injury.
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Which physiological change in a patient with septic shock indicates a poor prognosis?
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