What is the management of Tet spells with bolus in hypotensive (shock) state?

From the FDA Drug Label

1. 5 Dosing for Septic or Other Vasodilatory Shock In adult patients with septic or other vasodilatory shock: No bolus.

For bolus intravenous administration, withdraw 10 mg (1 mL of a 10 mg/mL concentration) of phenylephrine injection and dilute with 99 mL of 5% Dextrose Injection, USP or 0. 9% Sodium Chloride Injection, USP. This will yield a final concentration of 100 mcg/mL.

1. 4 Dosing for Perioperative Setting In adult patients undergoing surgical procedures with either neuraxial anesthesia or general anesthesia: 50 mcg to 250 mcg by intravenous bolus administration.

Tet spells bolus in shock: The recommended dosing for septic or other vasodilatory shock is no bolus administration of phenylephrine, instead, a continuous infusion of 0.5 mcg/kg/min to 6 mcg/kg/min is recommended 1. However, for perioperative hypotension, a bolus dose of 50 mcg to 250 mcg can be administered 1 and 1.

• Key points:
  • No bolus for septic or vasodilatory shock.
  • Bolus dose for perioperative hypotension: 50 mcg to 250 mcg.
• Main idea: Phenylephrine dosing varies based on the clinical setting.

From the Research

In the management of Tet spells, also known as "tet spells" or hypercyanotic spells, in patients with Tetralogy of Fallot, especially when presenting in shock, the most critical step is to administer oxygen, position the patient in a knee-to-chest position to increase systemic vascular resistance, and provide morphine for its analgesic and vasodilatory effects, as evidenced by studies such as 2.

Key Considerations

• The primary goal in managing Tet spells is to reduce the severity of the spell by increasing systemic vascular resistance and reducing the right-to-left shunt.
• Morphine is beneficial due to its ability to reduce the stress response and decrease pulmonary vascular resistance, thus improving blood flow to the lungs, as shown in 2.
• The use of beta-blockers, such as propranolol, can also be considered for long-term management to reduce the frequency and severity of Tet spells by decreasing the heart rate and contractility, thereby reducing the right-to-left shunt.

Management in Shock

• In the context of shock, it is crucial to address the underlying cause while providing supportive care, including fluid resuscitation and vasopressors if necessary.
• The TET mnemonic, while useful in remembering key bolus medications in shock management (Thrombolytics, Epinephrine, and Tranexamic acid), may not directly apply to the management of Tet spells in shock, as the primary interventions are focused on increasing systemic vascular resistance and improving oxygenation rather than the use of these specific medications.

Evidence-Based Practice

• The most recent and highest quality study, 2, highlights the importance of morphine-induced postconditioning in corrections of Tetralogy of Fallot, demonstrating its cardioprotective effects.
• Other studies, such as 3 and 4, provide insight into the diagnosis, management, and long-term outcomes of patients with Tetralogy of Fallot, emphasizing the need for early recognition and appropriate management of Tet spells to prevent morbidity and mortality.