Covid and Regional Anaesthesia

Currently we are at the peak of the second wave of pandemic. Availability of beds & oxygen is at nadir. The patients coming to us for surgery are the ones where surgery cannot wait. Mainly the load is obstetric. As a matter of COVID pandemic policy we are using regional anaesthesia unless contraindicated or the surgery demands general anaesthesia. The aim is to avoid/reduce aerosolization which is part & parcel of GA, despite the efforts to minimise it. The policy is to protect the anaesthesiologists, surgeons, OT staff & other patients as well. The present manuscript is to review the role of regional anaesthesia & its safe performance.


INTRODUCTION
Anaesthesiologists by virtue of their position at head end come under high-risk groups of healthcare providers. General anaesthesia involves airway interventions with aerosol generation [1,2,3]. The risk of infection to the anaesthesia provider is 6.6 times more [4]. In

Review Article
emergency & difficult airway scenarios the risk to the patient is also more from injury to failed intubation & post-operative pulmonary complications [5][6][7][8][9][10]. Lack of extended postoperative analgesia, associated nausea & vomiting, and the multiple drugs involved in balanced general anaesthesia having potential to interact with patient's medication which may include COVID medications are the drawbacks associated with GA. The American Society of Regional Anaesthesia (ASRA) [11], the European Society of Regional Anaesthesia and Pain Medicine (ESRA) and the European Society of Anaesthesiology (ESA) has published guidance on employing regional anaesthesia for patients with COVID-19. Our Indian counterpart AORA [12] (association of regional anaesthesia) has also come up with the statement.
The patient coming to us may be symptomatic or asymptomatic, rapid antigen negative or RTPCR (reverse transcriptase chain reaction) positive or negative, taking universal precautions is a must.

IS REGIONAL SAFE
The evidence suggests that regional anaesthesia including central neuraxial blockade can be safely administered in COVID patients & whatever the technique is chosen, it will not aggravate the COVID condition [13,14]. However, one must be watchful for hypotension which is likely to be an exaggerated response [15].

THE PATIENT STATUS
RTPCR -the gold standard -It detects nucleic acid of viral RNA. Sensitivity is 70%. So a negative test should not prelude standard protection protocol [16]. It can be supported by 2 negative RTPCR results in 48 hours & absence of suspected symptoms, or one negative test followed by negative HRCT 24 hr later [17]. This is practically impossible in most of the situations & patients are taken with a single RTPCR result. The lack of proper isolation facilities especially in peripheral settings & almost impossible task of testing the accompanying relatives of the patient further complicates the issue.
Rapid antigen-It only confirms a frank positive case in an emergency & negative does not rule out the disease.
The message is "Take universal precautions". Prevention is always better than cure.  [26].

THE POINTS TO BE NOTED DURING PAC
In a retrospective study of 34 patients with confirmed disease, it was found that there was a mortality of 20.5%, and ICU bed required for 44.1% of patients.

WHAT IS CONCEIVED ABOUT REGIONAL ANAESTHESIA? [27]
1. A reduction in aerosol-generating procedures (AGPs) and thereby both increased safety and a saving in the time, resource, and financial costs of personal protective equipment (PPE). 2. Preservation of immune function when compared with general anaesthesia 3. Improved postoperative analgesia minimising direct contact with caregivers, and earlier discharge. 4. Avoiding a general anaesthetic in patients with active COVID-19 undergoing urgent surgery is likely to be beneficial, but there is also a suggestion that mortality rates of patients with undiagnosed COVID-19 who subsequently undergo surgery is higher.
These facts are well established backed up by evidence.

WHAT ARE THE AREAS OF CAUTION TO BE CONSIDERED?
 Do we get more complacent with use of regional than with AGP generating procedures?  Is quiet patient under well conducted GA with full protection is better than RA as there is no coughing, no vomiting?
The disease spreads primarily via respiratory droplets and fomite transmission [28]. Droplets spread by gravityare up to <2 m. AGPs lead to more distant spread of the virus, & also remains airborne for a longer timer.
Coughing and sneezing are droplet-generating, but even talking and breathing also can generate aerosols. This must be remembered in an awake patient for whom droplet precautions alone would be used [29]. This is the most vulnerable group where a higher rate of infection has been found. [30].
PPE use is stratified into -1. Contact ,2. droplet, and 3. airborne precautions. Current guidance in such elective cases with a low risk of conversion to general anaesthesia remains to wear droplet precaution PPE only [31,32].

Simple Things Followed Strictly & Meticulously are Helpful: [34]
Limit the period of proximity between patient and healthcare worker while administering any regional.
Place a surgical mask on the patient.
Manipulation of oxygen therapy devices.
Limit/minimal sedation. (in view of possible low functional pulmonary reserve & subsequent complications) Adopt airborne precautions in all.

Few Tips about Nasal/ Mask Oxygenation
Install nasal oxygen catheters under the surgical mask.
Remember high gas flows can increase aerosol dispersion. So, keep it minimal [35].
Cough can also increase dispersion to even longer distances.
Face masks for supplementary oxygen administration replace nasal catheters efficiently and are preferable.
Surgical masks over face masks reduce aerosol dispersion.
Fresh gas flow administered to the patient should be as low as possible to maintain oxygen within normal parameters.
Prophylactic administration of an anti emetic drug is preferred to reduce the risk of vomiting and viral spread [12]

Caution with SAB
The SARS-CoV-2 virus has been isolated in the CSF; for this reason, avoid dripping during spinal anaesthesia [37] COVID-19 carriers, as already mentioned previously, can present hemodynamic instability, mainly after neuraxial blocks, and intense hypotension can occur [38,39]. Vasopressor may be required.
To date there are no specific recommendations as to management of post-puncture headache in patients withCOVID-19.
The sphenopalatine lymph node block should not be performed routinely because it can produce aerosols, increasing the risk of transmission of SARS-CoV-2 to health professionals.
The epidural blood patch should be considered carefully in view of the possibility of the virus in the CSF. There is the possibility of a significant introduction of viral load, with possible neurological complications [40] If required, it should be postponed to after recovery from infection.

Surgery on Upper Limb: [12]
Select a surgically congruent technique with least interference of respiratory function.
USG guidance is better than PNS to ensure success, even a combined technique, to avoid unanticipated GA.
Use sterile plastic drapes over the patient.
Ensure successful block/optimal operating conditions before the knife is on.
Can consider rescue blocks.
Brachial plexus block should be performed by the most experienced person. If in doubt, even experts should take into consideration the best possible USG image [41].

In patients with Demonstrable
Saturation of Less than 95%, Options for Proximal Humerus Surgery: 1. Ultrasound guided superior trunk block (12 15 ml) 2. Administer an ultrasound guided incremental interscalene brachial plexus block (ISB) through a catheter at C5 6, followed by a graded increase in LA volume in an aliquot of 3 ml at each time. This should be done under continuous monitoring of saturation and diaphragmatic excursions 3. Supraclavicular block: With ultrasound guided LA volume should not exceed more than 20 ml. However, with neurostimulation guided block the volume should not exceed more than 25 ml.

OBSTETRIC ANAESTHESIA [12]
 Pregnant patients from the containment zone will undergo RT PCR test as per ICMR guidelines  Consider neuraxial block as it minimizes the need for general anaesthesia in case of emergency caesarean section.  As the incidence of hypotension is likely to be higher, anaesthesiologist must be aware of the same.  The lower limit of platelet count for performing neuraxial procedures is 70,000 × 106/L17, to avoid spinal/epidural hematoma. However, respiratory compromise with general anaesthesia is much higher and hence neuraxial procedures at even lower platelet counts should be considered [42]  Though the risk of epidural or subarachnoid space seeding with viraemic blood, causing encephalitis or meningitis, is exceedingly rare, it remains a theoretical possibility [43,44]  Currently, there is no evidence to suggest vertical transmission, although transmission after birth due to contact with infectious respiratory secretions is possible [39]. It is advisable to separate the mother from the baby while diagnostic testing is being performed. Involve paediatricians early for caring for neonates born to COVID-19 mothers [45].  A recent report of a neonate born to a COVID-19 infected mother shows a possibility of in utero infection [45].  Meanwhile, ensure maximal level PPE (gown, gloves, facemask, and eye protection) for feeding and care  It is suggested, the elevated immunoglobulinM (IgM) are not transferred to the foetus via the placenta, during the 23 days between maternal infection and delivery [46 49] 7.1 Paediatric Regional Anaesthesia  The scope and play of regional anaesthesia is same as adults  Consider a good premedication unless contraindicated [50]. This will minimize the agitation and crying & contribution to more aerosolization  The face mask is not indicated in neonates and children in less than 2 years for the possibility of suffocation  The accepted practise to giving concomitant general anaesthesia shall hold sway for obvious reasons. Certainly, general anaesthesia with intubation and closed circuits with  appropriately sized filters would be preferred over face masks or LMA to minimize aerosol generation.  Practices of continuous epidural catheters and perineural catheters should be encouraged because of their opioid sparing effects.

Continuous Catheters: [12]
 We follow AORA Academy of Regional anaesthesia of India, published clinical guidelines for performance of regionals.

Safe practice is the best approach
Wear appropriate protection considering all possibilities.
Surgical mask to all patients.
Protect equipment like USG probe, machines with plastic covers.
Minimal personnel minimal drugs & equipment in the operation theatre.
Keep backup in ante room.

Appropriate technique appropriate experienced Anaesthesiologist
Prepare required drugs and put them in a dedicated plastic bag.
Use a block which will impact respiration least e.g., axillary block or infra-clavicular brachial plexus block.
Weigh Risks and benefits before using adjuvants and continuous perineural catheters.
Currently, there is no recommendation to adjust the doses of regional anaesthesia techniques.
Use US-guided peripheral nerve blocks.

No replacement to vigilance
Test the effect carefully before the knife is on to avoid conversion to GA Use the lowest oxygen supplement flow required to keep O2 saturation.
Check for/ rule out thrombocytopenia before neuraxial anaesthesia.
Be alert and ready for hypotension after neuraxial anaesthesia. Whenever possible, postpone epidural blood patch until recovery from acute infection.
After use, the US device must be disinfected.
Patient post-anaesthesia recovery should be performed on the same site where the procedure was performed.
Be ready for possible block failure and local anaesthetic systemic toxic reactions

CONCLUSION
The study discusses the policies to avoid/reduce aerosolization which is part & parcel of GA, despite the efforts to minimise it. The policy is to protect the anaesthesiologists, surgeons, OT staff & other patients as well.