The Intensive Care Manual - part 1 pdf

[...]... unit has about 1 second in which to exchange ch 01. qxd 11 /7/ 01 4 4:08 PM Page 4 The Intensive Care Manual (a) FIGURE 1 1 Physiology of oxygenation in lung under normal circumstances (a), during ˙ ˙ V/Q mismatch (b), and shunt (c) ch 01. qxd 11 /7/ 01 4:08 PM Page 5 1 / Respiratory Failure and Oxygen Delivery (b) I I , FIGURE 1 1 (continued) 5 ch 01. qxd 11 /7/ 01 6 4:08 PM Page 6 The Intensive Care Manual (c)... ch 01. qxd 11 /7/ 01 4:07 PM Page 1 CHAPTER 1 The Critically Ill Patient: Overview of Respiratory Failure and Oxygen Delivery MICHAEL J APOSTOLAKOS INTRODUCTION OXYGEN DELIVERY RESPIRATORY FAILURE OXYGEN CONSUMPTION Hypoxemia Hypercapnia SUMMARY 1 Copyright 20 01 The McGraw-Hill Companies Click Here for Terms of Use ch 01. qxd 11 /7/ 01 2 4:07 PM Page 2 The Intensive Care Manual INTRODUCTION The care of the. .. conditions intervene (Table 1 1) , the body’s ability to supply increases in ventilation is compromised, and therefore, hypercapnia can occur This may lead to respiratory failure ch 01. qxd 11 /7/ 01 10 4:08 PM Page 10 The Intensive Care Manual OXYGEN DELIVERY Oxygenation is simply one factor in oxygen delivery, which is one of the most important aspects to understand in the care of critically ill patients... = Cardiac output × (CaO2 − CvO2) Where CvO2 represents the content of oxygen in the venous blood The venous blood, however, is only 75% saturated, with a PvO2 of approximately 40 mm Hg By using the equations above, this calculates to an oxygen concentra- ch 01. qxd 11 /7/ 01 12 4:08 PM Page 12 The Intensive Care Manual tion of approximately 13 6 mL/L The oxygen consumption calculates to approxi˙ mately 250... Approaches to the Central Venous Circulation Central Venous Pressure Monitoring THORACIC BIOIMPEDANCE PLETHYSMOGRAPHY AND ESOPHAGEAL DOPPLER TECHNOLOGY MUCOSAL TONOMETRY CAPNOGRAPHY SUMMARY 15 Copyright 20 01 The McGraw-Hill Companies Click Here for Terms of Use ch02.qxd 11 /7/ 01 16 4:08 PM Page 16 The Intensive Care Manual INTRODUCTION Care of critically ill patients requires vascular access for either therapeutic... ovale When there is a patent foramen ovale and right-sided heart pressure is increased, blood can be shunted across the atria from the right side of the heart to the left side of the heart causing shunt and hypoxemia This can be diagnosed by a contrast echocardiogram ch 01. qxd 11 /7/ 01 8 4:08 PM Page 8 The Intensive Care Manual ASSESSMENT OF HYPOXEMIA When assessing hypoxemia, an understanding of the normal... barometric pressure PH2O is the partial pressure of water R is the respiratory quotient The A-a gradient is normally less than 10 mm Hg on room air In adults over age 65, normal values may extend up to 25 mm Hg Case Example An example of the usefulness of calculating the A-a gradient is demonstrated in the following case: A 2 1- year-old patient was admitted to the ICU from the emergency department (ED) with... through catheters of a least 20-gauge to prevent hemolysis; the rate of flow of transfusing blood can be significantly improved by dilution with saline, thereby decreasing viscosity ch02.qxd 11 /7/ 01 20 4:08 PM Page 20 The Intensive Care Manual The size of a catheter can be expressed in either gauge or French units, which are measures of external diameter Gauges range from 14 to 27 with the smallest... of ch 01. qxd 11 /7/ 01 4:08 PM Page 11 1 / Respiratory Failure and Oxygen Delivery 11 FIGURE 1 2 Oxyhemoglobin dissociation curve Note parameters, which shift curve to right and thus favor unloading oxygen 2,3-diphosphoglycerate (2,3 DPG), and an increased PCO2, all shift the oxyhemoglobin dissociation curve to the right (indicating a decreased affinity to bind oxygen) The opposite conditions shift the. .. be separated from the other causes of hypoxemia in that they are the only ones associated with a normal alveolar-aterial (A-a) oxygen gradient The alveolar-arterial (A-a) gradient is the difference between PAO2 and PaO2 The A-a gradient may be calculated from the following equation: A − a gradient = FIO2 (PB − PH2O) − PaCO2 R − PaO2 Where FIO2 is the fraction of inspired oxygen PB is the barometric pressure . apply to any claim or cause whatsoever whether such claim or cause arises in contract, tort or other- wise. abc McGraw-Hill 0-0 7 -1 3827 4-7 DOI: 10 .10 36/00 713 82747 This book is dedicated to our loving. Humanities Director, Surgical Intensive Care Unit Rochester, NY CHAPTER 11 : APPROACH TO GASTROINTESTINAL PROBLEMS IN THE INTENSIVE CARE UNIT Contributors xi fm 01. qxd 11 /7/ 01 4:07 PM Page xi JAMES. Professor of Anesthesiology/Critical Care Department of Anesthesiology/Critical Care Wake Forest University School of Medicine Winston-Salem, NC x Contributors fm 01. qxd 11 /7/ 01 4:07 PM Page x CHAPTER