Sepsis
/In today’s podcast, we try to provide an update on sepsis for OB/GYN’s. It’s a long one but hopefully full of lots of good information for your practice and knowledge.
Sepsis definitions have changed recently, put forth in 2016 the Third International Consensus Conference for the Definitions of Sepsis and Septic Shock Task Force. These marked a major departure from previous iterations, which were defined by the “SIRS” or “Systemic Inflammatory Response Syndrome” criteria. This also ushered in a new scoring system for sepsis evaluation, known as the Sequential Organ Failure Assessment tool, and a quick bedside version known as qSOFA.
Common obstetric and gynecologic etiologies include urinary tract infections and pyelonephritis; chorioamnionitis/endometritis; wound infections and necrotizing fasciitis; septic abortions; toxic shock syndrome; and ruptured tuboovarian abscess. Non-obstetric or non-gynecologic causes should also be considered. Some of these more common etiologies include gastrointestinal causes, such as appendicitis, diverticulitis, or peritonitis; respiratory causes, such as influenza or pneumonia; and skin infections including cellulitis.
In our hospital, we remember the primary interventions for sepsis using the acronym “BLAST”: Blood Cultures, Labs/Lactate, Antibiotics, Saline, Time.
B: Blood Cultures; L: Lactate/Laboratories
With the suspicion for sepsis, laboratory evaluation is essential. CBC, BMP, lactic acid, and blood cultures are often part of the initial workup.
Lactic acid production partially results from the shift of aerobic to anaerobic cellular metabolism, so it functions as a proxy marker of poor tissue perfusion. In sepsis, higher lactic acid levels have been associated with worsened outcomes. Surviving Sepsis Campaign guidelines do recommend guiding resuscitation to lactate normalization. The SMFM consensus statement does recommend lactate measurement for suspected sepsis in pregnancy.
Blood cultures are important to obtain upfront, prior to the initiation of antibiotic therapy. Even with an initial antibiotic exposure, blood cultures can become useless. Two sets of peripheral blood cultures, with each set consisting of aerobic and anaerobic cultures, are recommended (13). If an infection site is suspected and can be easily accessed for culture in a timely manner, cultures are recommended prior to antibiotic initiation.
In obstetric patients, the most common causes of sepsis include septic abortion, chorioamnionitis and postpartum endometritis, urinary tract infections, pneumonia, and gastrointestial origins such as appendicitis.
A: Antibiotics
Empiric antimicrobial therapy should be broad in coverage, but also directed towards the most likely source, if one is known. The SMFM consensus statement, the Surviving Sepsis Campaign, and the SEP-1 core measure promote administration of appropriate antibiotic therapy within three hours of presentation. Mortality risk in septic shock appears time-dependent with respect to antibiotic therapy based on observational data.
Combination or “double coverage” therapy for critically ill or neutropenic patients (using two antibiotics to cover the same spectrum of pathogen) is not recommended. However, one notable exception is a source of sepsis more commonly encountered by gynecologists: toxic shock syndrome (TSS).
TSS results from the production of noxious exotoxins by Streptococcus and is described with retained objects, such as tampons, in the vagina. The antibiotic therapy of choice in this case is a combination of penicillin and clindamycin, as clindamycin acts as a transcription inhibitor to the production of bacterial exotoxins.
S: Saline
Crystalloid fluid is the choice for initial resuscitation in severe sepsis or septic shock. The landmark trial on early-goal directed therapy (EGDT), published by Rivers in 2001, randomized patients to standard therapy versus targeted fluid therapy with placement of both central venous and arterial lines, with strict goals for mean arterial pressure (MAP), central venous pressure (CVP,) venous oxygen saturation, hematocrit, and urine output. Fluid administered prior to randomization in both arms was 20-30 cc/kg over 30 minutes. This has ultimately become the standard of care for initial fluid resuscitation.
In pregnancy, this may be overly aggressive, and predispose patients to pulmonary edema; thus, the SMFM consensus statement on sepsis in pregnancy recommends an initial bolus of 1-2 L. Frequent reevaluation of volume status should be performed.
T: Time
The SEP-1 core measure from CMS is predicated on two major time points, with time starting at the time of patient presentation with severe sepsis or septic shock. The SEP-1 bundle requirements at three hours and six hours are shown in Figure 2. The entirety of the “BLAST” protocol covers the initial, “three hour” time point.
The next marker is six hours, which states there should be a redrawn lactate if there was a diagnosis of severe sepsis or septic shock. There also should be a full physical examination, The reexamination can include central venous pressure measurement, central venous oxygen measurement, a bedside cardiovascular ultrasound, or a passive leg raise test as well. For obstetricians and gynecologists, likely the physical examination and passive leg raise are the most easily performed. This may not work in pregnancy due to aortocaval compression; thus, SMFM recommends continued bolus with small fluid volumes (250 - 500 cc) and close monitoring of vital signs to determine if patients are fluid responsive.
If patients in septic shock do not respond to fluid and are persistently hypotensive despite adequate fluid resuscitation, the SEP-1 core measure requires administration of vasopressors by the six hour mark. Norepinephrine is the primary choice in sepsis both in and out of pregnancy. Norepinephrine is associated with lower rates of arrhythmia and overall mortality compared with other vasopressors.
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We go into a lot more detail in the podcast on some additional points, but be sure to check out the SMFM Sepsis guideline for all the deep reading on this topic!