COMPARATIVE PERFORMANCE OFHUDSON FACE MASK WITH NASAL PRONGS IN THEMANAGEMENT OF EARLY POST OPERATIVE HYPOXAEMIA

Abstract

Background
Early post operative hypoxaemia is common after general anaesthesia irrespective of the
site or duration of surgery when patients breaths room air during their initial recovery
period. Oxygen is an effective therapeutic agent when given at FiO2> 21% . It, however, needs to
be prescribed, given in an adequate dose, and through an appropriate device. Variable
performance devices, especially, Face Mask and Nasal Prongs are the most commonly used
oxygen therapy devices employed post operatively in the sub-region.
This study was a prospective randomized study designed to compare the performance of Face
Mask and Nasal Prongs in the management of early post operative hypoxia. We also
determined the incidence of hypoxia in the studied population.

Methods
One hundred and twenty patients with American Society of Anesthesiologists ( ASA) I and II
physical status, aged 18-80 yrs undergoing elective surgery under general anaesthesia relaxant
technique werestudied.General anaesthesia was induced with i.v sodium thiopentone5mg/kgand
endotracheal intubation was facilitated with0.1 mg/kg of pancuronium. Anaesthesia was
maintained with Isoflurane (1.5– 2%) in 100% oxygen, andi.vpancuronium. Patients were
ventilated via a closed circuit system.
Analgesia was administered with i.v Diclofenac 1mg/kg, i.v Tramadol 1mg/kg and i.v Paracetamol
20mg/kg. At the end of surgery, patients were reversed of residual neuromuscular block with i.v
atropine 0.02mg and neostigmine 0.04mg. Post extubation, patients were given 100% oxygen via
a close-fitting mask and using the anaesthetic machine for 3minutes (Time 0).
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The patients were fully awake and had SPO2≥97% before transfer to the recovery room. On arrival
in the recovery room, 120 patients were randomly allocated into two groups: group A (Face
Mask) and group B (Nasal Prong), when their SpO2 decreased to ≤ 94%. The oxygen flow rate
was 4L/min through each of the devices. The SpO2, systolic blood pressure, heart rate and
respiratory rate were measured. The patientcomfort while on each of the devices were measured
using a modified VAS.
Result

The mean oxygen saturation (SpO2) on arrival in the recovery room before commencement
of oxygen therapy was similar in both groups: Group A (93.2± 7.0%) vs Group B (93.3± 2.6%),
p= 0.461. The increase in oxygen saturation after commencement of oxygen therapy was
significantly faster with Nasal prong (0.63 ±1.42 min) than in the Face Mask (1.78 ±1.10min), p
= 0.001. The maximum SpO2 obtained was significantly higher with Nasal prong (98.77±1.29%)
than97.63 ±1.89%, achieved with Face Mask (p = 0.001).

The patients in the two groups were also found to show statistically significant
differencesin the haemodynamicchanges, occuringwithin minutes of commencement of oxygen
therapy in the recovery room. During this period, mean systolic blood pressure was 130.2±16.6 in
Group A versus 123.3 ±15.2 in Group B, p=0.002, while the mean heart rate was (109.5 ±10.6) in
Group A versus(102.1 ± 16.2) in Group B, p=0.004.
There was no incidence of hypoxia or desaturation during oxygen therapy with the two
devices in this study.There was also no significant association between early postoperative
hypoxemia and site of surgery, duration of surgery or volume of infusion administeredintra
operatively.Nasal Prongs was significantly more comfortable in 91.7% of patients compared to
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Hudson Face mask in 61.7% of the patients, using modified VAS. This was a statistically
significant difference (p = 0.001).
Conclusion
This study has demonstrated that Nasal Prongs delivers oxygen faster than the Face Mask andwas
more comfortable for the patients in early postoperative hypoxemia. It alsoresulted in a higher
SpO2 levels and lower heart rate and respiratory rate, when compared with the Face Mask.