In a patient undergoing PCI in the cath lab who is already receiving dopamine and norepinephrine infusions, can low‑dose phenylephrine be added to support norepinephrine according to current guidelines?

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Huwag Magdagdag ng Phenylephrine sa Kasalukuyang Regimen

Hindi dapat magdagdag ng low-dose phenylephrine sa norepinephrine at dopamine sa isang pasyenteng nasa cath lab para sa PCI—ang tamang escalation ay vasopressin o epinephrine, hindi phenylephrine. 1

Bakit Hindi Phenylephrine ang Tamang Sagot

  • Ang Surviving Sepsis Campaign ay nagbibigay ng Grade 1C strong recommendation LABAN sa paggamit ng phenylephrine bilang first-line o routine vasopressor, dahil maaari nitong taasan ang blood pressure sa monitor habang sinisira ang microcirculatory flow at tissue perfusion. 1

  • Ang phenylephrine ay pure alpha-agonist na walang cardiac stimulation—maaari nitong pababain ang cardiac output sa pamamagitan ng reflex bradycardia at increased afterload, na delikado sa isang pasyenteng may ongoing ischemia sa cath lab. 1, 2

  • Ang phenylephrine ay impairs microcirculatory perfusion sa shock patients, na maaaring magpasama ng tissue hypoxia kahit tumaas ang arterial pressure. 2

Ang Tamang Escalation Algorithm

Unang Hakbang: I-optimize ang Norepinephrine

  • Ang norepinephrine ay dapat na first-line vasopressor, na sinimulan sa 0.05–0.1 µg/kg/min at titrated upang makamit ang MAP ≥ 65 mmHg. 1

  • Siguraduhing may adequate fluid resuscitation (minimum 30 mL/kg crystalloid) bago mag-escalate ng vasopressors. 1

Ikalawang Hakbang: Magdagdag ng Vasopressin

  • Kapag ang norepinephrine ay umabot na sa 0.1–0.25 µg/kg/min at ang MAP ay nananatiling < 65 mmHg, magdagdag ng vasopressin 0.03 units/min (fixed dose)—hindi ito dapat gamitin bilang monotherapy. 1

  • Huwag lumampas sa 0.03–0.04 units/min dahil ang mas mataas na doses ay nagdudulot ng cardiac, digital, at splanchnic ischemia nang walang karagdagang hemodynamic benefit. 1

Ikatlong Hakbang: Magdagdag ng Epinephrine (Hindi Phenylephrine)

  • Kung ang MAP ay hindi pa rin naaabot kahit may norepinephrine + vasopressin, magdagdag ng epinephrine na nagsisimula sa 0.05 µg/kg/min, titrating hanggang 0.3 µg/kg/min. 1, 3

  • Ang epinephrine ay may beta-adrenergic cardiac stimulation na makakatulong sa cardiac output, kumpara sa phenylephrine na pure vasoconstrictor lamang. 3

Ikaapat na Hakbang: Isaalang-alang ang Dobutamine

  • Kung ang MAP ay adequate (≥ 65 mmHg) ngunit may persistent signs ng tissue hypoperfusion (elevated lactate, low urine output, altered mental status), magdagdag ng dobutamine 2.5–20 µg/kg/min upang mapabuti ang cardiac output. 1

Ang Tanging Tatlong Sitwasyon Kung Kailan Pwedeng Gamitin ang Phenylephrine

Ang phenylephrine ay reserved lamang para sa: 1, 2

  1. Kapag ang norepinephrine ay nagdudulot ng serious life-threatening arrhythmias
  2. Kapag ang cardiac output ay documented na mataas ngunit ang blood pressure ay nananatiling mababa
  3. Bilang salvage therapy kapag lahat ng ibang agents ay nabigo na

Ang Problema sa Dopamine sa Regimen

  • Ang dopamine ay hindi dapat gamitin bilang first-line agent dahil nauugnay ito sa 11% absolute increase in mortality at mas mataas na incidence ng arrhythmias kumpara sa norepinephrine. 1, 3

  • Ang 2020 COVID-19 guidelines ay explicitly recommends AGAINST using dopamine kapag available ang norepinephrine, na may strong recommendation. 3

  • Ang low-dose dopamine para sa "renal protection" ay strongly contraindicated (Grade 1A)—walang benefit at dapat iwasan. 1, 3

Monitoring Requirements sa Cath Lab

  • Maglagay ng arterial catheter para sa continuous blood pressure monitoring habang ginagamit ang vasopressors. 1

  • I-monitor ang tissue perfusion markers tuwing 2–4 hours: lactate clearance, urine output ≥ 0.5 mL/kg/h, mental status, skin perfusion, at capillary refill. 1

  • Gumamit ng bedside echocardiography upang ma-assess ang cardiac output at ventricular function habang nag-titrate ng vasopressors, lalo na sa pasyenteng may cardiac dysfunction. 1

Common Pitfalls na Dapat Iwasan

  • Huwag gumamit ng phenylephrine bilang routine third agent—ito ay maaaring magtaas ng blood pressure numbers habang sinisira ang actual tissue perfusion. 1

  • Huwag mag-escalate ng vasopressin lampas sa 0.03–0.04 units/min upang subukang iwasan ang pagdagdag ng third agent—ang mas mataas na doses ay nagdudulot ng ischemic complications. 1, 3

  • Huwag magdagdag ng dopamine sa complex vasopressor regimen—ito ay magpapataas ng arrhythmia risk ng 2–3 fold at maaaring magpasama ng mortality. 3

References

1
Guideline

Vasopressor Management in Septic Shock

Praxis Medical Insights: Practical Summaries of Clinical Guidelines, 2026

2
Guideline

Management of Vasopressors and Inotropes in Neurogenic Shock

Praxis Medical Insights: Practical Summaries of Clinical Guidelines, 2025

3
Guideline

Management of Severe Shock with Vasopressors

Praxis Medical Insights: Practical Summaries of Clinical Guidelines, 2026

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Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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