While assessing a client on the first postoperative day following a total thyroidectomy, t… — NCLEX-RN

While assessing a client on the first postoperative day following a total thyroidectomy, the nurse observes the client experiencing severe anxiety, visible muscle twitching, and circumoral paresthesia. The rapid response team is activated, and a stat arterial blood gas (ABG) analysis is drawn, reporting the following values: pH $7.54$ , $PaCO_2$ $26$ $mm Hg$ , $HCO_3^-$ $23$ $mEq/L$ , and $PaO_2$ $96$ $mm Hg$ . Based on these findings, which initial action is most appropriate to mitigate the risk of impending seizures or tetany?

Instruct the client to breathe slowly and deeply into a paper bag or cupped hands.Answer
B
Prepare for the immediate administration of an intravenous sodium bicarbonate infusion.
C
Lower the head of the bed to a flat, supine position to enhance cerebral perfusion.
D
Initiate high-flow supplemental oxygen therapy via a non-rebreather mask.

Answer

The correct action is to instruct the client to breathe slowly into a paper bag or cupped hands to correct the respiratory alkalosis.

The client is exhibiting signs of uncompensated respiratory alkalosis (pH > 7.45 and PaCO2 < 35 mm Hg) driven by hyperventilation (anxiety/panic). In an alkalotic state, hydrogen ions dissociate from albumin molecules in the blood. This leaves empty binding sites on the albumin, which calcium ions quickly fill, sharply decreasing the amount of biologically active, free 'ionized' calcium. For a client who is already at peak risk for hypocalcemia following a total thyroidectomy (due to potential parathyroid gland injury), this sudden drop in ionized calcium rapidly precipitates acute tetany, manifesting as circumoral paresthesia and muscle twitching. Coaching the client to breathe into a paper bag allows the rebreathing of carbon dioxide. This corrects the hypocapnia and alkalosis, subsequently releasing calcium from albumin and rapidly increasing the free ionized calcium to mitigate the immediate risk of seizures.

Step-by-Step Solution

Analyze the arterial blood gas (ABG) values to determine the primary physiological derangement.

The pH is elevated (

7.54

) and the

PaCO_2

is decreased (

26

mm Hg

), indicating uncompensated respiratory alkalosis due to hyperventilation.

Accurate interpretation of diagnostic data is required to identify the root cause of the acute deterioration.

Correlate the acid-base imbalance with the surgical history and clinical symptoms.

Alkalosis causes hydrogen ions to dissociate from albumin, allowing more calcium to bind to these proteins. This sharply decreases active ionized calcium.

Understanding this physiological relationship explains why the hyperventilation is causing acute tetany (muscle twitching, paresthesia) in a client already at risk for hypocalcemia post-thyroidectomy.

Select the most appropriate immediate intervention to reverse the specific pathophysiological mechanism.

Having the client rebreathe their expired carbon dioxide corrects the hypocapnia and shifts the blood pH back toward normal, which releases calcium back into its ionized, active state.

Correcting the respiratory alkalosis is the fastest, most direct method to stabilize the ionized calcium and prevent a life-threatening seizure while pharmacological interventions are being prepared.

Key Concept

The physiological relationship between respiratory alkalosis, protein binding, and ionized hypocalcemia in post-surgical clients.

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