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Carbon Tetrachloride Toxicity
Clinical Assessment - History and Physical Exam

Course: WB2888
CE Original Date: December 31, 2017
CE Expiration Date: December 31, 2019
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Learning Objectives

After completing this section, you will be able to

  • Describe what is included in the initial history and physical exam of patients potentially exposed to carbon tetrachloride (CCl4).

Introduction

Symptoms and signs potentially associated with CCl4 exposure are nonspecific making a careful medical and exposure history essential to diagnosis.

The initial history and physical exam of patients potentially exposed to CCl4 can be used to

  • Determine possible sources and pathways of exposure to CCl4,
  • Detect symptoms and signs that could be attributable to CCl4 exposure, and
  • Reveal history of any preexisting or underlying condition(s) that might complicate the diagnostic and clinical approach to the patient.

This information guides development of a differential diagnosis and selection of laboratory/imaging studies, which are discussed in the next section.

Patient History

An exposure history should be taken as part of the patient medical history. This should cover occupational and non-occupational CCl4 exposure risks. See the "Sources of Additional Information" section later in this CSEM for links to ATSDR's Taking an Exposure History CSEM, Taking a Pediatric Exposure History CSEM, and Pediatric Principles CSEM. Additionally, a link is provided to the Exposure History Form, which is available for download in a "fillable" PDF form that can be printed and saved: Exposure History Form [PDF - 455 KB).

Environmental Exposure History

An environmental exposure history (non-occupational) for CCl4 can be used to obtain the following information:

  • Type of water supply,
  • Location and duration of residence,
  • Proximity to industry or National Priorities List (NPL) sites or both,
  • The patient's hobbies, and
  • History of exposure to other known hepatotoxic agents (e.g., medications and alcohol) .

Occupational Exposure History

The patient's occupational history is crucial. The information on the current occupation would be most valuable, especially in cases of acute toxicity. For each job held, the exposure history should include:

  • Name and location of the company,
  • Job title,
  • Description of chemical processes used,
  • Known toxic agents,
  • History of worker illness,
  • Enclosure of solvent-related processes,
  • Use of hood or other ventilation, and
  • Proper use of personal protective equipment (PPE).

Information on the specific constituents of the solvent-containing materials and other potentially hazardous substances used should be collected. This might necessitate requests for Safety Data Sheets (SDSs) from employers, suppliers, or manufacturers. Use and type of personal protective equipment should be determined. The occupational history should also include the patient's general assessment of the hygienic conditions of the work setting, including the availability of separate washing, changing, and eating facilities. Information about potential exposure(s) from the activities of coworkers should also be gathered from the patient.

Medical History

Medical history and a review of systems should include assessments of current and past diagnoses or symptoms of

  • Neurologic,
  • Hepatic,
  • Renal, and
  • Dermatologic disease.

It is important not to overlook the association between solvent exposure and conditions such as

  • Glomerulonephritis,
  • Contact dermatitis,
  • Cognitive impairment, and
  • Peripheral neuropathy [Rom and Markowitz 2007].

Patient's alcohol use should also be evaluated. The patient's complaints should be identified in terms of

  • Onset,
  • Duration,
  • Frequency and
  • Intensity.

Symptoms that vary in time with exposure are a function of the anesthetic property of organic solvents. Specially, dizziness, light-headedness, impaired concentration, and headaches that have a temporal relationship to solvent exposure are likely the result of acute CNS effects [Meredith et al. 1989; Rom and Markowitz 2007]. These symptoms are likely to resolve quickly after removal from the contaminated environment into a fresh air environment and might significantly improve or resolve by the time the patient is evaluated at a health care facility.

Physical Examination

After an acute exposure, the initial physical examination should concentrate on the neurologic system. Within 1 to 6 days after an acute exposure, the patient might develop severe hepatic necrosis and renal failure, which can affect the cardiovascular and pulmonary systems.

When performing the physical exam, emphasis should be placed on major organ systems likely affected by exposure to CCl4 (e.g., CNS, gastrointestinal, dermal, and hepatic). Note that lack of clinical findings on initial exam does not exclude potential carbon tetrachloride toxicity. The patient might show subclinical, delayed, or individual variability in the initial presentation.

Vital signs should be recorded, especially noting any abnormalities of heart rate or rhythm. Head, eyes, ears, nose, and throat should be examined noting any inflammation or irritation. The skin should be inspected, especially the hands, for signs of

  • Redness,
  • Drying,
  • Cracking, or
  • Fissuring.

Also check for signs of jaundice.

Chest examination should include assessment of the heart and lungs.

Abdominal exam should include palpation for liver and spleen size (i.e., hepatomegaly, hepatosplenomegaly, etc.) and tenderness.

A mental status examination should be conducted to evaluate

  • Alertness,
  • Orientation,
  • Cognition, and
  • Short-term memory.

Peripheral nerve function should be evaluated by assessing

  • Proprioception,
  • Deep tendon reflexes,
  • Motor strength,
  • Postural stability (Romberg test), and
  • Cutaneous sensibility to vibration, light touch, and pin prick (which should always be included in the evaluation).

Key Points

  • The occupational and environmental exposure history is essential to diagnosing CCl4 toxicity.
  • The physical examination should focus on major organ systems likely affected by exposure to CCl4 (e.g., CNS, gastrointestinal, dermal, and hepatic).
   

Progress Check

9. Which of the following is true regarding goals of the initial history and physical exam of patients potentially exposed to CCl4?

A. To determine possible sources and pathways of exposure to CCl4.
B. To detect symptoms and signs that might be attributable to CCl4exposure.
C. To obtain a history of any preexisting or underlying condition that might complicate the diagnostic and clinical approach to the patient.
D. All of the above.

Answer:

To review relevant content, see "Patient History" and "Physical Examination" in this section.

10. In general, patients over-exposed to CCl4 by any route PREDOMINANTLY exhibit which of the following manifestations?

A. CNS depression.
B. Hepatomegaly.
C. Pulmonary edema.
D. Nephritis.

Answer:

To review relevant content, see "Possible Signs and Symptoms of CCl4Toxicity" in this section.

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