Environmental
- The volatile anaesthetic gases are potent greenhouse gases – with a global warming potential hundreds to thousands times that of carbon dioxide
- Nitrous oxide (N2O) is also a potent greenhouse gas, with a very long lifespan in the atmosphere, and damages the ozone layer
- These gases contribute to global climate change
- Desflurane is by far the most damaging gas, and its concentration has been steadily increasing in the Earth’s atmosphere
- Desflurane also requires a heated vaporizer – 2x 100W heating elements
- Even when on standby and not in use, it uses 24W of electricity
- In a year, standby power use alone is 756,864 kilojoules or 757 megajoules (MJ) – 210 kWh – even more when it is actually used
- Most large screen LCD TV’s 120+cm (48+”) use less than 200 kWh per year – 10 hours usage + 14 hours standby per day
- One hour of desflurane is equivalent to 235-470 miles (375-750 km) travelled in a modern car – NOT including the electricity use above
- Adding N2O to reduce desflurane use is ineffective as N2O contributes the same amount to global warming
- Sevoflurane is approximately 10-20 times less harmful compared to desflurane
- Adding N2O to sevoflurane INCREASES greenhouse emissions by up to 19 times
- Volatile anaesthetics also contribute to operating room pollution
- Prolonged exposure to low concentrations of these gases can be an occupational hazard
- Exposure to trace amounts of anaesthetic gases may cause genetic damage equivalent to smoking 11-20 cigarettes per day
- 2008 study assessing sevoflurane genotoxicity in anaesthetists exposed to minute (0.2 parts per million) amounts of sevoflurane
- Volatiles may be implicated in Alzheimer’s dementia by inducing amyloid protein related factors
- This promotion of Alzheimer’s can actually be attenuated by propofol
- Concerns regarding miscarriages, foetal malformations, fertility
- 2011 study (survey) from Canada – increased congenital cardiac anomalies
- Prolonged exposure to low concentrations of these gases can be an occupational hazard
- Propofol, even taking include the additional disposables required, and the electricity used to run the pumps, is 4 orders of magnitude less harmful than desflurane. That’s ten thousand times less!
- The main environmental impact with propofol appears to be electricity to run the pumps. This can be negated by using renewable energy sources. Manufacturing of propofol and waste associated with discarded propofol seems to have negligible impact.
- Further information can be found here
Economical
- Historically, TIVA using propofol and remifentanil was more expensive when it comes to drug aquisition costs. In the 1980’s and 90’s, the volatile agent halothane and isoflurane were inexpensive compared to these new intravenous drugs.
- However, due to
- Remifentanil coming off patent
- Propofol prices falling
- Remifentanil prices falling
- New volatile agents such as desflurane costing more
- A Propofol/Remifentanil TIVA anaesthetic can be cheaper than sevoflurane, and more than 10 times cheaper than desflurane
- The exact costings are highly variable, but the above takes into account some wastage of the intravenous drugs.
- Propofol 200mg ($0.72) compares favourably to sevoflurane ($2.50 per hour at 1L/min) and desflurane ($22 per hour at 1L/min). Desflurane at 6% at 6L/min is over $2 per minute.
- Prices are in $AUD at 2016 prices at one institution
- Prices do vary worldwide as well, but the historical price premium for TIVA is rapidly diminishing
- Reduction in anti-emetic use is also seen with propofol TIVA, further reducing drug costs
- Improved recovery profile may translate to shorter stays in recovery rooms and day surgery centres, reducing staffing costs
Clinical
There are many clinical advantages to propofol TIVA, and these are well documented. [PubMed]
To summarise:
- Reduced PONV (post operative nausea and vomiting) [PubMed]
- Does NOT trigger malignant hyperthermia (a serious life threatening reaction with volatile anaesthetics that has a high mortality rate)
- Improved quality of awakening (reduced emergence delirium)
- Reduced incidence of airway complications (laryngospasm, bronchospasm) [PubMed]
- Does not potentiate neuromuscular blockers. Desflurane worse than sevoflurane. TIVA least. [PubMed]
- Reducing residual paralysis
- Less requirements for anticholinergic muscle relaxant reversal drugs [PubMed]
- Does not inhibit insulin secretion, and therefore less intraoperative hyperglycaemia [PubMed]
- May help prevent cancer recurrence and death from cancer recurrence in cancer surgery. Improved long term survival if TIVA used during cancer surgery instead of volatile gases
- Many studies showing that volatiles potentiate cancer growth (or inhibit the body fighting cancer)
- Propofol may have a protective effect (boosts the immune system against cancer)
- Some studies have found up to 50% increase in survival with TIVA versus volatile gases
- Gastric cancer (study out of China) – improved survival p<0.001; hazard ratio 0.65
- Oesophageal cancer (study from South Korea) – volatiles associated with worse overall survival; hazard ratio 1.58; p<0.001
- Breast cancer (study from South Korea) – lower rate of recurrence – hazard ratio 0.55; p=0.037
- Mixed – Breast cancer, colorectal, gynaecological (study from London, UK) – volatiles associated with hazard ratio 1.59 for death; p<0.001
- Breast, colon and rectal (study from Sweden) – 9% increase colon cancer survival p<0.001
- Further studies are underway to quantify this benefit, the actual benefit is still unknown
- Many studies above are not randomised – while they show an association, it does not equate to causation
- It has led to an increase of clinical trials in the past decade, as well as increased interest in the use of TIVA for cancer patients
- See this page for further details
- Reduced intraoperative bleeding and blood loss
- Studies in ENT surgeries suggest reduced blood loss
- Volatiles impair platelet activation by binding to platelet receptor integrin [PubMed]
- Volatiles impair platelet activation by binding to platelet receptor integrin [PubMed]
- Studies in ENT surgeries suggest reduced blood loss
- Reduced pain after surgery
- Some studies have reported less pain after surgery, when TIVA is used
- Propofol reduces opioid induced hyperalgesia compared with volatile agents
- May lead to less chronic pain after surgery (less pain at 3 months after surgery)
- Further trials are currently underway
- Maintains organ perfusion (avoids uncoupled vasodilation)
- Reduces ventilation perfusion mismatch in the pulmonary circulation (maintains HPV – hypoxic pulmonary vasoconstriction)
- TIVA has been preferred by many in thoracic surgery
- Reduces ICP changes in neurosurgery
- TIVA is almost ubiquitous in neurosurgery
- Lower intracranial volume improves surgical access
- Enables intraoperative neurophysiological monitoring
- TIVA is almost ubiquitous in neurosurgery
- Reduces uterine blood loss in post partum haemorrhage
- Volatiles can cause uterine atony and increases bleeding
- Reduces ventilation perfusion mismatch in the pulmonary circulation (maintains HPV – hypoxic pulmonary vasoconstriction)
- Volatile anaesthetics are controversial / relatively contraindicated in
- Neuromuscular dystrophies where the diagnosis is unclear
- Central core disease risk of malignant hyperthermia
- Central core disease risk of malignant hyperthermia
- Xeroderma pigmentosum
- Genotoxic / disease aggravation
- Long QT syndrome
- Risk of torsades de pointes, malignant arrhythmias
- Liver disease / Hepatotoxicity
- Well known with halothane, sevoflurane seems safer – although mild transient injury reported. Multiple case reports of liver damage with desflurane
- Clinical significance unclear
- Well known with halothane, sevoflurane seems safer – although mild transient injury reported. Multiple case reports of liver damage with desflurane
- Kidney disease / Renal toxicity
- Well known with methoxyflurane, concerns with Compound A causing kidney injury with sevoflurane
- Clinical significance unclear
- Manufacturers and US FDA recommend against low flow < 1L/min anaesthesia, and to use 2L/min or greater after 2 hours
- The higher flow rates reduce Compound A accumulation, but at the expense of increasing sevoflurane usage and its release into the atmosphere
- Clinical significance unclear
- Well known with methoxyflurane, concerns with Compound A causing kidney injury with sevoflurane
- Neuromuscular dystrophies where the diagnosis is unclear
- TIVA is well suited to anaesthesia in “remote” areas
- No vaporisers or gas scavenging equipment required
- Can reduce the risk of accidental awareness in difficult airway cases (when ventilation is difficult or interrupted) as intravenous route ensures delivery of anaesthetic
- Obviously the converse is also true in that TIVA can also cause awareness if intravenous delivery is interrupted or inadequate