Pathophysiology

Instructions

• This week’s case study will introduce concepts related to the pulmonary system and shock states. Read the scenario and thoroughly complete the questions. Some of the answers will be short answers and may not require a lot of details. For example: what is the most common organism to cause a hospital acquired infection? The answer is pseudomonas aeruginosa. Answers to questions that relate to the pathogenesis of a disease must include specific details on the process. For example: How does hypoxia lead to cellular injury? Simply writing that a lack of blood flow, causes a lack of oxygen available to the cell and the cell cannot function without oxygen is not sufficient. This type of response is NOT reflective of an advanced understanding of the concept or graduate level work. This answer should discuss the cascade of events leading to the lack of oxygen and how it specifically impairs cellular function. All answers to these type of questions should address the effects at the cellular level, then the effects on the organ and then the body as a whole. Additionally describing the normal anatomical and/or physiologic processes underlying the pathogenesis will be necessary to thoroughly answer the question.

It is very likely that you will need to reference multiple sources to answer the questions thoroughly. Your text book will not necessarily have all the answers. Only professional sources may be used to complete the assignment. These include text books, primary and secondary journal articles from peer reviewed journals, government and university websites, and publications from professional societies who establish disease management guidelines and recommendations. Sources such as Wikipedia or other generic websites are not considered professional references and should not be used to complete the case studies.

• Reason for Consultation:
  Desaturation to 64% on room air 1 hour ago with associated shortness of breath.

History of Present Illness:
Mrs. X is 73-year-old Caucasian female who was admitted to the general surgery service 3 days ago for a leaking j-tube which was surgically replaced 2 days ago. This morning at 07:30, the RN reported that the patient was sleeping and doing fine, then the CNA made rounds at 0900 and Mrs. X was found to be mildly dyspneic.  Vital signs were checked at that time and were; temperature 38.6, pulse 120, respirations 20, blood pressure 138/38.  O2 sat was 64% on room air.  The general surgeon was notified by the nursing staff of the hypoxia, an order for a chest x-ray and oxygen therapy were given to the RN. The O2 sat is maintaining at 91-92% on 4L NC. The patient was seen and examined at 10:10 a.m.  She reported that she has had mild dyspnea for 2 days that has progressively gotten worse. She does not use oxygen at home.  Her respiratory rate at the time of this visit was 20 and she feels short of breath. She has felt this way in the past when she had pneumonia.  She is currently undergoing radiation treatment for laryngeal cancer and her last treatment was 1 to 2 weeks ago.  She reported that she has 2 to 3 treatments left.  She denied any chest pain or previous history of CHF. Review of her vital signs showed that she had been having intermittent fevers since yesterday morning.  Of note, she was admitted to the hospital 3 weeks ago for an atrial fibrillation with RVR for which she was cardioverted and has not had any further problems.  The cardiologist at that time said that she did not need any anticoagulation unless she reverted back into A-fib. 

Review of Systems: 
Constitutional:  Negative for diaphoresis and chills.  Positive for fever and fatigue.
HEENT:  Negative for hearing loss, ear pain, nose bleeds, and tinnitus.  Positive for throat pain secondary to her laryngeal cancer.  
Eyes:  Negative for blurred vision, double vision, photophobia, discharge and redness.  
Respiratory:  Positive for cough and shortness of breath. Negative for hemoptysis and wheezing.  
Cardiovascular:  Negative for chest pain, palpitations, orthopnea, leg swelling and PND.  
Gastrointestinal:  Negative for heartburn, nausea, vomiting, abdominal pain, diarrhea, constipation, blood in stool and melena.  
Genitourinary:  Negative for dysuria, urgency, frequency, hematuria and flank pain.  
Musculoskeletal:  Negative for myalgias, back pain and falls. 
Skin:  Negative for itching and rash.  
Neurological:  Negative for dizziness, tingling, tremors, sensory change and speech changes.  
Endocrine/hematologic/allergies:  Negative for environmental allergies or polydipsia.  Does not bruise or bleed easily.  
Psychiatric:  Negative for depression, hallucinations and memory loss.

Past Medical History: 

1.    Diabetes mellitus that was diagnosed 12 years ago with neuropathy. This resolved after gastric bypass surgery, which she had approximately 3 years ago.

2.    Laryngeal cancer

3.    Hypertension

4.    Hypercholesterolemia  

5.    Pneumonia

6.    Arthritis

7.    Hypothyroidism

8.    Atrial fibrillation  

9.    Acute renal failure

10.Chronic kidney disease, stage IV – 4 months ago a renal biopsy was completed, which showed focal acute tubular necrosis and patchy tubular atrophy, moderate to severe interstitial fibrosis with patchy acute and chronic interstitial nephritis, normal cellular glomeruli with no white microscopic evidence of a primary glomerulopathy. Baseline creatinine is 1.9.

11.Peptic ulcer disease

12.Skin cancer

13.Anemia

14.Osteoporosis

Past Surgical History:

15.Gastric bypass 4 years ago

16.Closure of mesenteric defect.

17.Radical neck resection on 1 year ago.

Family History:

18.Mother had diabetes diagnosed at age 55 and high blood pressure. Deceased.

19.Father had heart disease diagnosed at age 60. Deceased.

20.She had a sister with diabetes, thyroid disease, CKD, on dialysis, with unknown etiology.

Social History:
She denies any smoking or alcohol use.  She denies any drug use.

Medications:

21.Calcitriol 0.5 mcg PO every other day

22.Vitamin B12 2500 mcg sublingual every Monday and Thursday

23.Docusate sodium 100 mg PO BID

24.Fentanyl patch 100 mcg every 72 hours

25.Gabapentin 800 mg PO BID

26.Levothyroxine 50 mcg daily

27.Multivitamin 1 PO Daily

28.Oxybutynin 5 mg PO BID

29.Hydrocodone 5/325 1-2 tablets every 6 hours PRN pain

Allergies:
She is allergic to Cipro, which causes Uticaria and hives, contrast dye, honey and bee venom, adhesive, and sulfas, which causes hives

Physical Examination: 
Vital signs:  38.6, 120, 20, 138/38, 64% on room air.  She is maintaining O2 sat of 91 to 92 on 4 liters nasal cannula.  
Constitutional:  She is somnolent.  Oriented to person and place.  Appears ill and mildly dyspneic.
Head:  Normocephalic and atraumatic.  Nose:  Midline, right and left maxillary and frontal sinuses are nontender bilaterally. 
Oropharynx:  Clear and moist. No uvula swelling or exudate noted.  
Eyes:  Conjunctivae, EOM and lids are normal.  PERL. Right and left eyes are without drainage or nystagmus.  No scleral icterus.
Neck:  Normal range of motion and phonation.  Neck is supple.  No JVD.  No tracheal deviation present.  No thyromegaly or thyroid nodules.  No cervical lymphadenopathy noted bilaterally.
Cardiovascular:  rapid rate, S1 and S2 without murmur or gallop.  Brachial, radial, dorsalis pedis, and posterior tibial are 2+/4+ bilaterally.
Chest: Respirations are regular and even with mild dyspnea. Lungs are coarse and with some rales in the posterior bases.
Abdomen:  Soft.  Bowel sounds are active, nontender, no masses noted.  No hepatosplenomegaly noted.  No peritoneal signs.  
Musculoskeletal:  Full range of motion of the bilateral shoulders, wrists, elbows.
Neurologic:  Somnolent.  Cranial nerves II-XII are intact.
Skin:  Warm and dry.  
Psychiatric:  Mood and affect are normal.  Calm and cooperative.  Behavior, judgment is intact.

Laboratories and Diagnostics: 
WBC 7.2, Neutrophil 63% 
Creatinine 2.0, BUN 45, Na 144, Potassium 4.4 
BNP 242
Lactate 1.0
All other labs are unremarkable
Chest x-ray: Right lower lobe infiltrate 
EKG: NSR, no ST or T wave changes 

One hour after your saw Mrs. X, you get a call from the RN to report that her BP is now 75/40, pulse is 140, RR is 34 and dyspneic, temperature is 39.6 and she is minimally responsive.  Mrs. X is transferred to the MICU. 

Upon re-evaluation of Mrs. X you note that she is obtunded, struggling to breath, using accessory muscles and O2sats are 85% on a Non-rebreather. She is intubated and placed on a ventilator. A central line is placed and confirmation obtained via CXR. A foley is placed and fluid resuscitation has begun. 

WBC 20
Hgb 12
HCT 36
Platelets 98,000
Na 148
Chloride 110
Potassium 5.6
Glucose 190
Creatinine 3.0
BUN 68
Albumin 3.0
Anion Gap 21
Lactate 5.2
Procalcitonin 15, INR is 1.0, aPTT 23
ABG (prior to intubation) pH 7.28, PCO2 36, HCO3 17

EKG: Atrial Fibrillation with RVR at 156
CVP 3

Answer the following questions:  

30.What are 4 plausible differential diagnoses for Mrs. X’s hypoxemia that are specific to her clinical scenario? How would each diagnosis cause a hypoxemia?

31.What is your final diagnosis for the hypoxemia?

32.What are the most likely organisms to cause the diagnoses you identified in question 2?

33.Upon initial evaluation what category of sepsis was Mrs. X?

34.Upon re-evaluation what category of sepsis was Mrs. X?

35.Why is a gram negative bacteremia more serious than one caused by a gram positive organism?

36.What is the most likely source of Mrs. X sepsis?

37.What is a CVP and what does a value of 3 indicate? Why is Mrs. X CVP 3?

38.What is a Procalcitonin and what is its purpose?  

Hypoxemia: Causes, Symptoms, and Treatment
Hypoxemia is a medical condition which is characterized by a reduction in the levels of partial pressure of oxygen in the arterial blood. Scroll down to learn about the causes and symptoms of hypoxemia along with the treatment options.
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Our body needs oxygen to carry out the functions like cellular respiration and energy metabolism which are essential for its survival. One is therefore most likely to experience distressing symptoms in event of a decrease in the levels of oxygen. The term ‘hypoxemia’ refers to a medical condition that is characterized by a decrease in the partial pressure of oxygen in the arterial blood (PaO2). PaO2 is measured in millimeters of mercury (mm Hg or Torr). It refers to the pressure exerted by oxygen in a mixture of other gases. Arterial Blood Gas (ABG) testing helps measure PaO2.

Though these medical conditions are in some way related to reduction in the levels of oxygen in the body, these are distinct medical conditions. Here’s some information that will help you distinguish hypoxemia from the rest of the aforementioned conditions.

What is Hypoxemia?

This condition occurs when the pulmonary alveoli (microscopic sacs in lungs where exchange of oxygen and carbon dioxide takes place) are starved of oxygen. In this condition, a substantial decrease is observed in the levels of partial pressure of arterial oxygen. Under normal circumstances, partial pressure of oxygen in arterial blood should be within 95 to 100 mmHg. When the partial pressure of arterial oxygen in the blood falls below 80 mmHg, one is diagnosed with severe hypoxemia.

Also referred to as oxygen desaturation, hypoxemia should not be confused with medical conditions such as anoxia, asphyxia, hypoxia or anemia. Hypoxemia refers to a condition that is characterized by low oxygen content and low partial pressure of oxygen in arterial blood. The term ‘hypoxia’ refers to the deficiency of oxygen in the body as a whole or in some specific part of the body. ‘Asphyxia’ is a condition that is characterized by the absence of oxygen along with the accumulation of carbon dioxide. ‘Anoxia’ refers to the absence of oxygen in the body tissues or in the arterial blood. This implies extremely low levels of oxygen in the body. ‘Anemia’ is another medical condition that is characterized by a decrease in the number of red blood cells or low levels of hemoglobin in the blood. While the oxygen content in the arterial blood is low in people who are anemic, the partial pressure of oxygen in the arterial blood doesn’t decrease.

Arterial Oxygen Content

The arterial oxygen content can be calculated with the help of the following equation:

Arterial Oxygen Content = (Hgb x 1.36 x SaO2) + (0.0031 x PaO2)

In the equation given above, Hgb stands for the hemoglobin, SaO2 is the percentage of hemoglobin saturated with oxygen and (PaO2) refers to the partial pressure of arterial oxygen.

Symptoms

The symptoms of hypoxemia will vary depending on the extent to which the partial pressure has fallen.

Symptoms of Mild Hypoxemia

Restlessness
Anxiety
Disorientation, confusion, lassitude, and listlessness
Headaches

Symptoms of Acute Hypoxemia

Cyanosis (Skin appearing bluish due to insufficient oxygen)
Cheyne-Stokes respiration (irregular pattern of breathing)
Elevated blood pressure
Apnea (temporary cessation of breathing)
Tachycardia (increased rate of heartbeat, more than 100 per minute)
Hypotension (abnormally low blood pressure, below 100 diastolic and 40 systolic. Here, as an effect of an initial increase in cardiac output and rapid decrease later.)
Ventricular fibrillation (irregular and uncoordinated contractions of the ventricles)
Asystole (severe form of cardiac arrest, heart stops beating)
Polycythemia (abnormal increase in the number of red blood cells. The bone marrow may be stimulated to produce excessive RBCs in case of patients suffering from chronic hypoxemia)
Coma

Causes

Hypoxemia is usually triggered off by respiratory disorders.

Chronic obstructive pulmonary disease (COPD)
Airway obstruction
Acute respiratory distress syndrome
Pneumonia
Pneumothorax (collapsed lung)
Emphysema
Congenital heart defects
Pulmonary embolism (blood clot in lungs)
Pulmonary edema (fluid in lungs)
High altitude ascension could also lead to low partial pressure of oxygen in the arterial blood.

These are some of the conditions that could cause hypoxemia. Additionally, hypoxemia may also be caused as a result of one or a combination of the following

Hypoventilation: This refers to a condition wherein the oxygen (PaO2) content in the blood decreases and a marked increase in the levels of carbon dioxide is observed. This lowered PaO2 content can cause hypoxemia.

Low Inspired Oxygen: The FiO2 content in the blood is called the fraction of inspired oxygen in the blood. A decrease in this fraction of inspired oxygen may cause hypoxemia.

Right to Left Shunt: A right-to-left shunt refers to a condition in which there is a transfer of blood from the right side of the heart to its left side. An opening between the atria, ventricles, or blood vessels can lead to this. Structural defect or a problem in a heart valve can also result in right to left shunt.

Ventilation-Perfusion Mismatch: This is a condition in which an imbalance between the volume of gas expired by the alveoli (alveolar ventilation) and the pulmonary capillary blood flow is seen. This mismatch may cause hypoxemia.

Diffusion Impairment: In this condition, a marked reduction is seen in the oxygen movement from the alveoli to capillaries. This restricted movement may trigger hypoxemia.

More often than not, it is difficult to decide one single cause of hypoxemia in acute illnesses. It also becomes almost impossible to determine the extent of contribution of the causes of hypoxemia in such cases.

Treatment Options

Now that you have some idea about the circumstances under which one may develop hypoxemia, let’s move on to the treatment options for this pathological condition.

Mechanical Ventilation: Mechanical ventilation is a mechanism by which it is possible to aid or substitute spontaneous breathing mechanically. Continuous Positive Airway Pressure (CPAP) refers to a type of device that forces a steady stream of air into the nasal passage. This flow is set at a pressure that can overcome obstructions, thereby preventing the airway from closing. The pressure to be maintained should be determined through careful observation.

Supplemental Oxygen Therapy: In severe cases, it becomes essential to administer oxygen to the patient. Oxygen may be supplied through oxygen concentrators, cylinders or tanks. However, it is crucial to determine the precise levels of oxygen to be administered. Special care needs to be taken during supplemental oxygen therapy for infants. Supplemental oxygen therapy and CPAP are usually prescribed together as a treatment for hypoxemia. This is particularly effective for treating hypoxemia caused due to hypoventilation.

Transfusion of Packed RBCs: Packed red blood cells refers to the concentrate of red blood cells obtained after the removal of plasma in the blood. Packed red blood cells can be transfused as a treatment option for patients suffering from hypoxemia. This is known to increase the oxygen-carrying capacity of the blood. Sufficient care should be taken during the blood transfusion to avoid infections. This form of treatment cannot be used in case of patients who develop polycythemia (which is characterized by abnormally high RBC count) as a result of chronic hypoxemia.

Increasing Inspired Oxygen: This form of treatment is effective for hypoxemia that develops as a result of hypoventilation or due to the reduction in inspired oxygen.

Since hypoxemia can be caused by serious medical conditions, it is extremely essential to identify the underlying cause. Treating the underlying condition can certainly help to bring back the partial pressure of oxygen in arterial blood to normal. Drug therapy, oxygen therapy and lifestyle modification can certainly help in normalizing the partial pressure of oxygen in arterial blood.
Read more at Buzzle: http://www.buzzle.com/articles/hypoxemia-causes-symptoms-and-treatment.html

Common bacterial causes of sepsis are gram-negative bacilli (for example, E. coli, P. aeruginosa, E. corrodens, and Haemophilus influenzae in neonates). Other bacteria also causing sepsis are S. aureus, Streptococcus species, Enterococcus species and Neisseria; however, there are large numbers of bacterial genera that have been known to cause sepsis. Candida species are some of the most frequent fungi that cause sepsis. In general, a person with sepsis can be contagious, so precautions such as hand washing, sterile gloves, masks, and clothing coverage should be considered depending on the patient’s infection source.

What are the risk factors for sepsis?

The following groups are at increased risk for sepsis:

• The very young and the elderly are at greatest risk
• People who are very ill due to an infectious agent
• People in an intensive-care unit
• People with weakened or compromised immune systems
• People with devices such as IV catheters, breathing tubes, or other devices
• People with extensive burns
• People with severe trauma

 

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