Chapter 2

Measuring clinical parameters

Richard Aspinall

CHAPTER CONTENTS

Introduction

Procedure: To measure the body temperature

Procedure: To measure the pulse rate by palpation of the femoral artery

Procedure: To measure the pulse rate using a stethoscope

Procedure: To measure the pulse rate by palpation of the chest

Procedure: To measure the pulse rate using an oesophageal stethoscope

Procedure: To measure the respiratory rate by direct observation

Procedure: To measure the respiratory rate using a stethoscope

Procedure: To measure the respiratory rate using an oesophageal stethoscope

Procedure: To assess capillary refill time (CRT)

Procedure: To measure the electrical activity of the heart using an electrocardiogram (ECG)

Procedure: To measure the percentage of oxygen (oxygen saturation) in the blood using a pulse oximeter

Procedure: To measure central venous pressure (CVP)

Procedure: To measure arterial blood pressure using a non-invasive technique

Procedure: To measure carbon dioxide levels using a mainstream capnograph

Procedure: To measure carbon dioxide levels using a sidestream capnograph

Procedure: To measure urine production

Procedure: To measure tear production

Procedure: To measure intraocular pressure (IOP)

INTRODUCTION

Diagnosis of a patient's condition is based on a thorough clinical examination followed by a range of diagnostic tests. Part of the clinical examination includes the measurement of certain basic indicators of the body's function, known as the clinical parameters. Among the easiest to measure and therefore the most commonly performed are body temperature, pulse or heart rate and respiratory rate. Once these are known, they are compared to normal values for that species and the significance of the result is evaluated in the context of the symptoms. Later, once treatment has started, the parameters can be monitored and used as indicators of the progress of the disease.

Clinical parameters such as the percentage of blood gases or blood pressure require the use of complicated equipment but are essential measurements during anaesthesia and for monitoring the progress of the critically ill and hospitalized patient.

Measurement of clinical parameters and the monitoring of changes in their levels are essential parts of patient care. The veterinary surgeon must be able to rely on the veterinary nurse being able to perform the procedure correctly and accurately, and be confident that the nurse understands that when the results are abnormal, some action must be taken to return them to normal.

This chapter describes the methods of measuring these parameters in detail so that the veterinary nurse can approach the process with a degree of understanding and use the more complicated apparatus without fear.

Procedure: To measure the body temperature (Table 2.1)

Equipment

Mercury or digital thermometer.

Table 2.1

Normal clinical parameters in the dog and cat

Clinical parameter Dog Cat Body temperature 38.3–38.7 °C 38.0–38.5 °C Pulse rate 60–180 beats/min 110–180 beats/min Respiratory rate 10–30 breaths/min 20–30 breaths/min Capillary refill time 1–2 seconds 1–2 seconds Oxygen saturation Close to 99% Close to 99% Arterial blood pressure: systolic/diastolic Puppy: 108/60 mmHg Kitten: 123/63 mmHg   Adult: 141/81 mmHg Adult: 129/70 mmHg Central venous pressure 3–7 cm H2O 3–7 cm H2O Carbon dioxide concentration End-tidal: 35–54 mmHg End-tidal: 32–35 mmHg   Inspired: less than 8 mmHg Inspired: less than 8 mmHg Volume of urine produced 1–2 ml/kg bodyweight/hour 1–2 ml/kg bodyweight/hour Volume of tears produced 15–25 ml/min when measured using Schirmer strips 15–25 ml/min when measured using Schirmer strips Intraocular pressure 25 mmHg 25 mmHg

1. Action: Place the animal in a comfortable standing position on a table.

    Rationale: If the patient feels uncomfortable or insecure it will try to escape.

2. Action: Ask an assistant to restrain the dog gently by placing one arm around the neck and the other around the chest. Ensure that the dog is relaxed and quiet. Cats should be held lightly with both hands around the shoulders, or place one hand under the chin and the other around its chest, pulling it close to your body.

    Rationale: In this position, the animal will feel comfortable and unrestricted; however, the assistant will be able to react quickly if it tries to jump off the table.

3. Action: Select either a mercury or digital thermometer.

    Rationale: Choice of instrument depends on availability.

4. Action: Lubricate the end with K-Y jelly or a similar lubricant.

    Rationale: Lubrication reduces the discomfort of insertion into the rectum.

5. Action: Shake the mercury down to the bulb or check that the digital thermometer is switched on and displaying a reading.

    Rationale: If the mercury is not shaken down the new reading will be inaccurate.

6. Action: Gently, but firmly, insert the instrument into the rectum through the anus. A slight rotating action may help entrance through the rectal sphincters. Cats, particularly, may require patient gentle pressure before the sphincters relax.

    Rationale: In animals, the oral route is not practical but the rectal route is easy and well tolerated.

7. Action: Leave the thermometer in position for at least 30 seconds.

    Rationale: The mercury has to have time to warm up and expand.

8. Action: Clean the end of the thermometer by wiping with a paper cloth or cotton wool.

    Rationale: This prevents transmission of disease to another animal the next time the thermometer is used.

9. Action: Read the mercury thermometer by looking for the line of mercury against the scale. Read off the figures on the digital thermometer.

    Rationale: The glass of the thermometer magnifies the mercury line and makes it easier to read.

10. Action: Record the reading on the hospital record or clinical record.

    Rationale: To monitor rises or falls in the body temperature.

11. Action: Shake down the mercury or reset the digital reading.

    Rationale: To prepare the thermometer for use in the future.

12. Action: Place the bulb of the instrument in the disinfectant container.

    Rationale: This prevents transmission of disease to another animal the next time the thermometer is used.

Procedure: To measure the pulse rate by palpation of the femoral artery (Table 2.1)

1. Action: Place the animal in a comfortable standing position on a table.

    Rationale: If the patient feels uncomfortable or insecure it will try to escape.

2. Action: Ask an assistant to restrain...