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20 Current Essentials of Critical Care Pulse Oximetry Essential Concepts • Finger, ear, or other cutaneous probe measures transmission or reflectance of red and infrared light through tissue • Pulsatile absorbance (“beat-to-beat”) determines percentage of oxyhemoglobin in blood • Oxyhemoglobin, carboxyhemoglobin, and methemoglobin read as “oxyhemoglobin” • Pulsatile waveform essential for calculation; low perfusion, hy-potension, arterial disease, motion artifacts interfere with mea-surement • Correlates well with arterial blood O2 saturation Essentials of Management • Use for routine monitoring of patients in ICU and during en-doscopy, bronchoscopy, minor surgery, suctioning, sleep apnea episodes, bronchodilator therapy • Use to adjust supplemental oxygen therapy, including mechan-ical ventilation • Provides estimate of arterial oxygenation; still need arterial blood gases for PaCO2 and pH. • Do not use to exclude significant carboxyhemoglobinemia (eg, after smoke inhalation) • May not be accurate during cardiopulmonary resuscitation • Attach to ear lobe or finger according to manufacturer’s in-structions • Check for pulsatile waveform on monitor (if provided) • If waveform is poor or pulse oximeter does not provide an ad-equate reading, try other locations Pearl Very high methemoglobin levels have the peculiar effect of causing the pulse oximeter to read 75% regardless of concentration or oxy-genation. Reference Lee WW et al: The accuracy of pulse oximetry in the emergency department. Am J Emerg Med 2000;18:427. [PMID: 10919532] Chapter 1 Monitoring & Support 21 Upper GI Bleeding, Prevention Essential Concepts • 10–25% incidence of shallow, stress-induced ulceration of gas-tric mucosa with subclinical or clinically important upper GI bleeding in critically ill patients; associated with poor outcome, increased mortality • May have clinical bleeding or persistent unexplained fall in he-moglobin • Risk factors: mechanical ventilation, coagulopathy, thrombocy-topenia, renal failure, burns, postsurgical, possibly lack of en-teral feeding, aspirin; may be due to cytokine-mediated decrease in upper GI mucosal resistance to gastric acid, H pylori, multi-organ system failure, impaired hemostasis, medications, de-creased mucosal blood flow Essentials of Management • Give prophylactic therapy for all patients receiving mechanical ventilation, with thrombocytopenia, qualitative platelet dys-function, coagulopathy, significant burns, renal or liver failure • Consider in all patients in ICU, especially if hypotension, low cardiac output, inability to feed enterally • Sucralfate, a nonantacid, possibly associated with less nosoco-mial pneumonia; may be less effective • For antacid therapies, best results with pH . 4.0 (measurement of pH not clinically indicated) • Ranitidine, 150 mg IV per day, continuous infusion or every 8 hours, or famotidine 20 mg IV every 12 hours; adjust for renal insufficiency. • Alternative: pantoprazole 40 mg IV daily for 5–7 days, then switch to oral pantoprazole or omeprazole Pearl Patients with highest risk for stress-related upper GI bleeding are those receiving mechanical ventilation and those with disorders tend-ing to lead to bleeding. Reference Steinberg KP: Stress-related mucosal disease in the critically ill patient: risk factors and strategies to prevent stress-related bleeding in the intensive care unit. Crit Care Med 2002;30(6 Suppl):S362. [PMID: 1207266] This page intentionally left blank 2 ICU Supportive Care for Specific Medical Problems Burn Patients.................................................................................... 25 Chronic Renal Failure Patients.......................................................... 26 Pregnant Patients............................................................................. 27 Solid Organ Transplant Recipients................................................... 28 23 This page intentionally left blank ... - tailieumienphi.vn
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