core temperature monitoring: essential for an optimized ... · core temperature monitoring:...

Department of Infection Prevention 11/2015 Egil Lingaas

Oslo University Hospital

Core temperature monitoring: essential for an optimized

perioperative care

Egil Lingaas

Department of Infection Prevention


Oslo, Norway

SEORNA, Stockholm, November 26th 2015



Background

Surgical patients are at risk of developing

hypothermia at any stage of the

perioperative pathway.

Inadvertent perioperative hypothermia is a

common but preventable complication,

which is associated with poor outcomes for

patients.



Adverse outcomes of perioperative hypothermia

Morbid myocardial outcomes

Surgical site infection

Coagulopathy

Increased allgogeneic transfusions

Negative nitrogen balance

Delayed wound healing

Delayed postanesthetic recovery

Prolonged hospitalisation

Shivering

Patient discomfort



Inadvertent perioperative

hypothermia Implementing NICE guidance

2008

NICE clinical guideline 65



Patients at higher risk of perioperative

hypothermia

Any two of the following:

ASA grade II to V

preoperative temperature below 36.0°C

undergoing combined general and regional

anaesthesia

undergoing major or intermediate surgery

at risk of cardiovascular complications.

NICE



Definition of hypothermia

• Hypothermia: a patient core temperature

of below 36,0°C

• Preoperative: 1 hour before induction of

anaesthesia

• Intraoperative: the total anaesthesia time

• Postoperative: 24 hours after entry into

the recovery area in the theatre suite

NICE



Each patient should be assessed for their risk of inadvertent perioperative hypothermia and potential adverse consequences before transfer to the theatre suite. = measurement of temperature

Preoperative phase

NICE



Preoperative warming

forced air warming should be started

preoperatively on the ward or in the emergency

department (unless there is a need to expedite

surgery because of clinical urgency)

Forced air warming should be maintained

throughout the intraoperative phase

If the patient’s temperature is below 36.0°C

in the hour before they leave the ward

or emergency department

NICE



Intraoperative phase

The patient’s temperature

should be measured and

documented before

induction of anaesthesia

and then every 30 minutes

until the end of surgery.

Induction of anaesthesia

should not begin unless

the patient’s temperature

is 36.0°C or above.



Postoperative phase

The patient’s temperature should be measured

and documented on admission to the recovery

room and then every 15 minutes

Ward transfer should not be arranged unless the

patient’s temperature is 36.0°C or above

If the patient’s temperature is below 36.0°C, they

should be actively warmed using forced air warming

until they are discharged from the recovery room or

until they are comfortably warm. NICE


Oslo University Hospital Arkilic CF et al. Anesth Analg 2009;91:662

Why don’t just ask the anesthesiologist?

In fact, someone did ….


Oslo University Hospital Arkilic CF et al. Anesth Analg 2009;91:662

Are anaesthesiologists able to estimate patient thermal status?


Oslo University Hospital Torossian A. Eur J Anaestesiol 2007;24:668

October 13th 2004:

8081 patients in 316 hospitals in 16 European

countries

Temperature was monitored in 19.4 % of patients

Active warming was used for 38.5 % of patients



So, where to measure ….?

And with what technology….?

Methods for temperature measurement

Expansion

–Mercury, alcohol etc.

Liquid crystal

Infrared sensor

Electronic

–Thermistor

–Thermocouple

Heat flux (without active thermoelement)

Zero heat flux (with active thermoelement

Non-invasive methods (skin) Axilla

Usually 1-2 oC lower than actual core

temperature

Measurement errors frequent

Slow

Forehead

1. Liquid crystal - thermochrome substance

changing colour according to the temperature

Not accurate enough

2. Thermistors and thermocouples

About 2 o C must be added, but still a rather

inaccurate estimate of core temperature

Non-invasive methods (skin, contd)

Temporal artery

Inaccuracy caused by environmental

temperature and sweating

Generally not recommended for clinical

needs



Temporal artery thermometry

Kimberger O et al. Anest Analg 2007;105:1042

The sensitivity for detecting hypothermia (< 35.5oC) was 0.29,

and the specificity was 0.93.

The positive predictive value for hypothermia was 0.31, and the

negative predictive value was 0.95

CONCLUSIONS:

The results of this study do not support the use of temporal

artery thermometry for perioperative core temperature

monitoring;

the temporal artery thermometer does not provide information

that is an adequate substitute for core temperature measurement

by a bladder thermometer.



Temporal artery thermometry

Hebbar K al. Pediatr Crit Care Med 2005;6:557



Minimally invasive methods Oral

Dependent on patient compliance

Not very reliable

influenced by previous food intake, mucosal inflammation, air circulation in mouth

Continuous measurement not feasible

Tympanic 1. Infrared/indirect

Very inaccurate and artifact-prone (position cerumen etc.

2. Direct

Uncomfortable for patient

Risk of tympanic perforation



Infrared aural canal thermometers

Imamura M et al. Acta Anaesthesiol Scand 1998;42:1222



Infrared aural canal thermometers

Imamura M et al. Acta Anaesthesiol Scand 1998;42:1222

Conclusion: We conclude that none of the tested aural canal

infrared thermometers was sufficiently accurate and precise for

perioperative use



Minimally invasive methods (contd)

Rectal Better than other minimally invasive methods

High temporal latency depending on the filling of

the ampulla recti, with delays up to 1 h.

Still less accurate than aesophageal and bladder

temperature measurement



Most non-invasive methods are

unpresise

Temperature Measurement

Core Sites

–Pulmonary artery

–Distal esophagus

–Nasopharynx

–Tympanic membrane by thermocouple

Other generally-reliable sites

–Bladder



All “core sites” are more or less

invasive



Invasive methods for core temperature

measurement

Nasopharyngeal Option primarily for the anaesthezised ventilated

patient

Offers adequate accuracy (1)

Uncomfortable in non-anaesthezied patients

Not suitable for pre-operative measurement

(1) Maxton FL et al. J Adv Nurs 2004;45:214




measurement (contd.)

Esophageal High accuracy

Easy to attach to patient

Not very prone to artifacts

Rather uncomfortable for the anaesthezised

ventilated patient





measurement (contd.)

Bladder temperature High accuracy, but may produce false values with

low urine output

Low risk of dislocation



Oslo University Hospital Sato H et al. Eur J Anesthesiol 2008;25:805

Urinary bladder temperature



Urinary bladder temperature

Sato H et al. Eur J Anesthesiol 2008;25:805

Offset (oesophageal – urinary bladder):

– 0.13 + 0,32 - 0.46 + 0.45

Bland and Altman comparison:



The gold standard core temperature

The temperature measured next to the

heart (e.g. pulmonary artery)

Brain temperature

Both methods are extremely invasive



Non-invasive measurement of

core temperature



Zero Heat Flux

Based on thermic isolation of an area of the skin

and an actively warming thermoelement

that is heated until there is no more heat transfer

between the patient and the environment.


Oslo University Hospital Lees DE et al. Southern Med J 1980; 73:1322

Zero Heat Flux

Zero-heat flux thermometry

Warm Core

Cool

Environment

Heater

This point is the same

temperature…

...as this point

Skin

Insulator

Insulator

Isothermal

tunnel

Bringing the core to the surface

30 seconds

3 minutes

1 minute


Oslo University Hospital Lees DE et al. Southern Med J 1980; 73:1322

Zero Heat Flux


Oslo University Hospital Kimberger O et al. J Anaesth 2009;103:226

Results:

98 % of all values were within + 0.5 oC of oesophageal temperature.

Sensitivity and specificity for detection of hypothermia were 0.77 and

0.93 respectively.

Conclusions:

The new double-sensor thermometer is sufficiently accurate to be

consideres an alternative to distal oesophageal core temperature

measurement, and may be particularly useful in patients undergoing

regional manaesthesia


Oslo University Hospital Teunissen LPJ et al. Physiol Measurement 2011;32:559

Zero Heat Flux



Zero Heat Flux

Oesophageal

Rectal

Zero heat flux

Forehead skin



Zero Heat Flux



Continuous monitoring by zero heat flux methodology

during 30 whipple operations

Conclusions

The use of temperature monitoring for control of

core temperature is important for patient safety

during surgery.

Monitoring should start before surgery (at the

ward), and continue throughout the perioperative

phase.

Zero heat flux technology eliminates the need for

invasive monitoring, is monitoring core temperature

and facilitates continuous monitoring througout the

perioperative period

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