Sepsis and Shock

source: Pocket Medicine, 2022

Shock

• Tissue hypoxia due to ↓ tissue perfusion and hence ↓ tissue O2 delivery and/or ↑ O2 consumption or inadequate O2 utilization
• Typical signs include HoTN (SBP <90 mmHg or drop in SBP >40 mmHg), tachycardia, oliguria (UOP <0.5 cc/kg/h), Δ mentation, metabolic acidosis ± ↑ lactate
• Hard to diagnose as ↑ SVR can maintain SBP, but tissue perfusion poor; shock index (HR/SBP) >0.9 and pulse pressure [(SBP - DBP)/SBP] <25% clues to significant shock

Hemodynamic Profiles of Various Forms of Shock (NEJM 2013;369:1726)

Type of Shock	right atrium	PCWP	cardiac output	systemic vascular resistance
Hypovolemic	↓	↓	↓	↑
Cardiogenic	normal or ↑	↑	↓	↑
RV infarct/massive pulmonary embolism	↑	normal or ↓	↓	↑
Tamponade	↑	↑	↓	↑
Distributive	variable	variable	usually ↑ (can be ↓ in sepsis)	↓
Surrogates: right atrium ≈ jugular venous pressure (1 mmHg = 1.36 cm H2O); pulmonary edema on CXR implies ↑ PCWP; UOP ∝ cardiac output (barring AKI); delayed capillary refill (ie, >2-3 sec) implies ↑ systemic vascular resistance

Definitions

Sepsis

• Life-threatening organ dysfxn (SOFA ≥2) due to infection
• Quick SOFA (qSOFA): ≥2 of the following: RR ≥22, ΔMS, SBP ≤100 mmHg

Septic shock

• Sepsis-induced circulatory and cellular/metabolic abnormalities severe enough to ↑ mortality; hypotension requiring pressors for MAP ≥65 and lactate >2 despite adequate fluid resuscitation

Sequential Organ Failure Assessment (SOFA): ↑ points for worsening organ dysfxn: respiration (↓ P:F ratio); coag (↓ plt); liver (↑ bili); CV (↓ MAP or ↑ pressors); CNS (↓ GCS); renal (↑ Cr or ↓ UOP)

MANAGEMENT (Crit Care Med 2021;49:e1063)

Fluids

• Aggressive IV fluid resuscitation (30 mL/kg) admin in boluses w/in 3 h of presentation
• Crystalloid as good as colloid for resuscitation (JAMA 2013;310:1809; NEJM 2014;370:1412)
• No consistently seen benefit of balanced crystalloid (lactated Ringer's, Plasma-Lyte) vs. normal saline in terms of mortality, organ failure or need for RRT (NEJM 2018;378:829 & 2022:386:815)
• NaHCO3 may ↓ mortality & need for renal replacement therapy if AKI & pH <7.2 (Lancet 2018;392:31)
• Predictors of fluid responsiveness: pulse pressure variation >13% with respiration (Chest 2008;133:252); resp. variation in IVC diam, or >10% ↑ in pulse pressure w/ passive leg raise. Static CVP poor surrogate.
• After early resuscitation, if ALI/ARDS, target CVP 4-6 mmHg because additional fluids may be harmful → ↑ ventilator/ICU days (NEJM 2006;354:2564; Chest 2008;133:252)

Pressors & inotropes

• MAP target 65 mmHg as good as 80-85 and ↓ AF (NEJM 2014;370:1583; JAMA 2020;323:938)
• Norepinephrine: ↓ arrhythmia & mortality c/w dopamine (NEJM 2010;362:779; Crit Care Med 2012;40:725) and is pressor of choice in septic shock
• Vasopressin: adding to norepi (vs. using high-dose norepi) ↓ risk of AF & RRT by ˜¼ (JAMA 2018;319:1889)
• If refractory vasoplegia: angiotensin II (Giaprezza), methylene blue, steroids (vide infra)
• If targets (see below) not reached after adequate fluids and pressors, consider inotropes

Targets

• Lactate clearance (≥20%/2 h) as effective as ScvO2 to guide resusc. (JAMA 2010;303:739)
• Targeting capillary refill time ≤3 sec (check q30min) as good if not better than lactate clearance (JAMA 2019;321:654)

Antibiotics

• Start empiric IV abx as soon as possible after recognition of severe sepsis or septic shock; every hr delay in abx admin a/w 7.6% ↑ in mortality (Crit Care Med 2006;34:1589), abx admin w/in 3 h of presentation in the ED a/w ↓ in-hospital mortality (NEJM 2017;376:2235)
• If possible, obtain 2 sets of BCx before urgently starting abx (but do not delay abx)
• Broad gram-positive (incl MRSA) & gram-neg (incl highly resistant) coverage, ± anaerobes
• Procalcitonin-guided cessation (not initiation) ↓ mortality (Crit Care Med 2018;46:684)
• Empiric micafungin in critically ill Pts w/ Candida colonization & sepsis of unknown etiology ↓ invasive fungal infxns & tended ↑ invasive fungal infxn-free survival, espec. in Pts w/ 1,3-b-D-glucan >80 (JAMA 2016;316:1555)

Steroids (Crit Care Med 2018;46:1411)

• Hydrocortisone 50 mg IV q6 + fludrocortisone 50 μg via NGT daily in septic shock ↓ duration of shock and may ↓ mortality (NEJM 2018; 378:797 & 809)
• Consider in Pts w/ refractory shock on escalating doses of pressors

Early Goal-Directed Therapy (EGDT)

• Historically: IVF & pressors for MAP ≥65 mmHg, CVP 8-12 mmHg, UOP ≥0.5 mL/kg/h; inotropes & PRBCs for ScvO2 ≥70% in 6 h (NEJM 2001;345:1368)
• However, now in era of early abx and adequate fluid resuscitation, no ↓ in mortality w/ EGDT vs. current usual care, and ↑ hospital costs (NEJM 2017; 376:2223)