*5.2.2 Vascular access*

*Special Considerations in Human Airway Management*

native [16, 41].

must be developed.

carries significant risks [16].

**5.2 Technical considerations**

*5.2.1 Fluid generation and handling*

removal of air bubbles [16, 17, 47].

tion success rate especially among new users [44, 45].

successfully tested on the ISS (project IVGEN) [16, 46].

intravenous fluids exist as a foamy liquid [16, 17].

*5.1.5 Choice of anaesthetic technique*

A notable mention: the depolarising muscle relaxant succinylcholine is contraindicated due to disuse atrophy of muscles and changes in the neuromuscular junction, and the increased risk of hyperkalemia after prolonged exposure to microgravity [17, 39]. Instead, rocuronium is recommended to be used as an alter-

One of the limiting aspects of the anaesthesia protocol for microgravity is that it should be carried out by a small crew of non-medical personnel, with limited training. In several low-income countries, anaesthetic procedures are regularly performed by non-medical personnel, with relatively low complications. Simplified versions of the protocols—one which can easily be followed by non-physicians—

The worst case scenario approach should be the basis for making the choice of the anaesthetic technique. It must be borne in mind that astronauts who may require anaesthesia in space may have to be managed by nonmedical personnel with limited training, in case the crew medical officer (CMO) is incapacitated or deceased. In addition, they maybe hypovolemic, deconditioned, at a risk for rhythm

Although ultrasound guided regional anaesthesia may be used safely and successfully, it requires considerable training [16, 38, 42, 43]. Spinal anaesthesia is not feasible in microgravity, its safety and efficacy is unpredictable because the heavy local anaesthetic solutions used depend on gravity. Epidural anaesthesia may be used, but it also requires considerable training and absolute asepsis, and therefore

General anaesthesia with endotracheal intubation is suitable for all types of surgical conditions and is the recommended choice of anaesthetic technique. Intubation, in general, is facilitated by use of general anaesthesia and muscle relaxants [16]. Furthermore, use of video laryngoscopy also increases the intuba-

Intravenous (IV) fluids have a limited shelf life and usually remain unused during that period. Shipping and storing them is expensive due to the added weight and the wastage of valuable storage volume. It is however expedient, and necessary to be able to generate IV fluids on demand using drinking water. This process was

Fluids and gases do not separate in space, owing to their different densities, which complicates fluid handling and drug preparation. Hence most drugs and

It is advisable that injectable drugs be carried in prefilled syringes. Needleless vial adapters that allow direct drug aspiration into the syringe without the need for a needle to pierce the vial septum are also preferred. Experiments have been successfully conducted by NASA Scientific and Technical Information Program for

Another important concern is that many medical devices such as anaesthetic vaporisers and suction equipment, that depend on gravity induced separation of

fluids and gases, do not function properly in microgravity [17, 37].

disturbances and gastric aspiration, and intolerant to succinylcholine [16].

**202**

During a medical emergency, vascular access may be difficult to obtain. In space, securing the body of the IV administrator as well as mastering fine motor skills to perform the required task can be a challenge. Also, microgravity causes small objects to float away. Sharp objects such as IV cannulae can present a potential hazard to the crew [47].

Using ultrasound to obtain central venous access either autonomously or robotically is currently under development. An intraosseous access kit has also been included in the ISS medical gear [16].
