Radiation exposure of Intensive Care Trauma Patients
Ross Freebairn
Outline
Nuclear Powered Intensive Care
Radiation Exposure of Intensive Care Trauma Patients
Ross Freebairn
Intensive Care Services
Hawke's Bay Hospital, Hastings, NZ
Rainbow Warrior, Auckland July 1985
1985- Rainbow Warrior
* Greenpeace ship en route to Mururoa atoll to protest against French nuclear testing and the radiation damage in the Pacific.
* Sunk in Auckland Harbour - in the an act of State-sponsored terrorism by French agents.
Risks of Radiation Damage in NZ
Terminology
Cumulative Effective Dose (CED)
= ? (Dose Length Product x Tissue weighting factor)
- Takes into account the different biological effects of absorbed radiation on
different body organs
- Expressed as milli-Sieverts (mSv)
Tissue weighting factors
Routine CXR in ICU
* Of 645 CXRs performed in medical patients,
- 127 (19.7%) led to one or more management changes.
* In the 66 surgical patients with ICU stay <48 hrs,
- 15.4% of routine CXRs changed management.
* 35 surgical patients with an ICU stay > 48 hours,
- 26% of 100 routine films changed management.
* Chahine-Malus, N et al Crit Care 5:5, 271-5 (2001)
* Of 74 mechanically ventilated ICU patients,
- 13 (17.6%) new major findings discovered only by CXR.
* Hall, JB, White, SR and Karrison, T Efficacy of daily routine chest
radiographs in intubated, mechanically ventilated patients.Crit Care Med 19:5,
689-93 (1991)
Routine CXR
* Several studies have done a very limited cost accounting of the potential
savings
- The overall impact on patient outcome has not been investigated.
- A true assessment of cost-effectiveness has yet to be determined.
* However
- Radiation exposure ( 0.02mSv) is low.
* What about other radiological investigations?
Radiation Doses Equivalent
CT Scans: How bad?
* CT accounts for the single largest radiation exposure in trauma patients.
* I CT Body = 500 CXR
* Exposure to 100 mSv could result in a solid organ cancer or leukemia in 1 of
100 people.
Trauma Resuscitation
* A = airway
* B= breathing
* C= circulation
The New Resuscitation
* A = airway
* B= breathing
* C= CT scan
Trauma guidelines: Abdo
Trauma guidelines: Abdo
Traumatic Resuscitation
* A = accuse
* B= blame
* C= criticize
The problem
* Multiple injured trauma patients receive a substantial dose of radiation.
* Radiation exposure is cumulative.
* The low individual risk of cancer becomes a greater public health issue when
multiplied by a large number of examinations.
- 29 000 cancers and 14500 deaths annually in the USA.
* Though CT scans are an invaluable resource and are becoming more easily
accessible, they should not replace careful clinical examination and should be
used only in appropriate patients.
Has CT usage increased in trauma ?
* Calculate the cumulative effective radiation dose received by ventilated
trauma patients from admission to discharge from ICU.
* Compare 2 time periods
- compare the number of CT's performed
- cumulative effective dose
Methods
- A retrospective analysis of patient clinical and radiological data
- 2 cohorts of 40 consecutive adult trauma admissions ventilated during ICU
admission to Hawkes Bay ICU
- starting 1/1/04 and 1/1/09
Results: the 2 cohorts compared
Total CT scans during ICU stay
Total Radiation in ICU (mSv)
Median and Quartiles
Daily Radiation in ICU (mSv)
Median and Quartiles
So what does this mean?
* There has been an increase in the radiation dose exposure of ICU trauma
patients in recent years, largely due to complexity of the CT scans.
* Increased radiation exposure is consistent with other studies.
* What evidence is there of benefit?
Similar studies
* CT accounts for the single largest radiation exposure in trauma patients
Hui, CM et al. Can J Surg 2009; 52:147-152
* Increase in the mean number of CT exams per patient in 2007 compared with 2003
(4.41 v 3.44)
Salottolo, K et al. Crit Care Med 2009; 37: 1336-1340
Alternatives
* MRI:
- Access (timeliness)
- Access (monitoring & resuscitation)
* FAST/ US scan:
- Reliability & reproducibility
- Only detects presence of fluid.
*
Alternatives
* MRI:
- Access (timeliness)
- Access (monitoring & resuscitation)
* FAST/ US scan:
- Reliability & reproducibility
- Only detects presence of fluid.
* Sequential Clinical Examination
Avoid routine repeat scans
Of 692 patients
* In no patient without clinical deterioration did a change in management arise
from a repeat routine Head CT
* A Glasgow Coma Scale score less than 15 (13 or 14),
* age higher than 65 years,
* multiple traumatic lesions found on first head CT,
* interval <90 minutes from arrival to first head CT
- predicted independently a worse RRHCT.
Routine repeat Head CT is unnecessary in MHI.
Velmahos, G et al Routine repeat head CT for minimal head injury is unnecessary.
J Trauma (2006) 60:3, 494-9;
But -repeat routine CT scans are being advocated
* Routine follow-up CT scans
- beneficial in those patients with MBI
- worsening CT findings may lead to
* higher levels of medical management
* neurosurgical intervention.
* Some patients may be asymptomatic
* a prospectively randomized multi- centered trial would be beneficial.
* Bee, TK, et al Necessity of repeat head CT and ICU monitoring in patients with
minimal brain injury.Trauma 66:4, 1015-8 (2009)
Monitoring Use
* Prospectively monitor CT requests:
- What is expected to be found
- What intervention / management change will result from scan
- Audit the scan indications , scan results, and interventions that arise .
Marie Curie
* 1903, awarded Nobel prize in Physics
- with Pierre Curie, and Henri Becquerel
* 1911 awarded Nobel prize in Chemistry
* 1934 died from aplastic anaemia almost certainly contracted from exposure to
radiation.
* Much of her work had been carried out in a shed, without taking any safety
measures.
* She had carried test tubes containing radioactive isotopes in her pocket
remarking on the pretty blue-green light that the substances gave off in the
dark.
|
Ministry of Health
