Impact of Opioid Free Anesthesia on Outcome After DIEPflap Surgery
Condition: Major and Minor Surgical Complications
Study type: Observational [Patient Registry]

Summary: 
      The Deep Inferior Epigastric Perforator free flap (DIEPflap) involves the transfer of
      abdominal tissue to the breast using microsurgery. Flap failure is rare today, but is
      devastating.

      Blood flow in a DIEPflap decreases during the first hours. Many anesthetic factors like low
      cardiac output, hypothermia and surgical stress cause vasoconstriction or thrombosis.

      A stable anesthesia during these long procedures improves flap perfusion. Postoperative
      nausea and vomiting (PONV) is frequent and might have an impact.

      Opioid free anesthesia (OFA) reduces PONV. The anti-inflammatory and vasodilator effects of
      the drugs dexmedetomidine and lidocaine might improve free flap perfusion.

      The primary outcome counted all complications. The secondary outcomes were PONV, pain, opioid
      consumption, skin flap temperature and length of hospital stay.

      Patients get according to attending anesthesiologist an opioid or opioid free anesthesia
      without any randomization but based on availability of competence.
    

Detailed description: 
      The investigators included all patients in the hospital database.belgium who underwent
      DIEPflap surgery between Jan 2014 and April 2019. All patients entering the hospital provided
      consent to allow retrospective data analysis without patient identification.

      Because patient assignment to an operating day was determined without knowing who would
      perform the anesthesia on a few exceptions, the choice of opioid free anesthesia (OFA) or
      opioid anesthesia (OA) in most cases was random. Patients were classified as receiving OFA
      when no opioids were given pre- or intra- operatively until wound closure. Opioids given
      after wound closure were counted as post-operative opioids. Patients who received a lower
      dose of intra-operative opioids by using additives were still classified as OA.
      Post-operative opioid free analgesia was classified as receiving no opioids after wound
      closure until discharge from hospital in patients not receiving medium- or long-acting
      opioids, pre- or intra-operatively.

      The method of reaching OFA remained stable since 2014. Dexmedetomidine was given in a first
      loading dose of 0.3 mcg/kg 15 minutes before induction, a second loading dose of 0.1 mcg/kg
      at induction followed by an infusion of 0.1 mcg/kg/h for maintenance. Lidocaine is given as a
      loading dose of 1 mg/kg at induction followed by 1 mg/kg/h for maintenance. A Ketamine
      loading dose of 0.1 mg/kg is given at induction with an extra bolus of 0.7 mg/kg (or max 50
      mg) before incision followed by an infusion of 0.1mg/kg/h.

      Post-operative analgesia was further improved by continuing very low doses of dexmedetomidine
      (0.05 mcg/kg/h), ketamine (0.05 mg/kg/h), and lidocaine (0.5 mg/kg/h) for the first hours
      (maximum 5 hours) with the possibility of giving a bolus of 10 mg lidocaine, 1 mg ketamine
      and 1 mcg dexmedetomidine every 15 minutes.

      OA was induced with sufentanil (0.1 - 0.3 mcg/kg) and continued with extra boli (0.1 - 0.2
      mcg/kg) or a continuous infusion of remifentanil (0.20 - 0.35 mcg/kg/h). Since 2014 more and
      more additives like clonidine, dexmedetomidine, ketamine and lidocaine were given as a single
      additive at the induction to reduce the total dose of intraoperative opioid use. Nevertheless
      these patients were still counted as OA.

      All patients getting OFA got a strict goal directed fluid therapy with an average amount of
      fluids between 600 and 1200 ml. Patients on OA got a more liberal fluid therapy resulting in
      total amounts between 3000 and 5000 ml. For each patient the total amount of fluids given
      intra operative and the duration of the surgical procedure is calculated.

      Following demographic data was retrieved: age, body mass index (BMI), American society of
      anesthesiology (ASA) score, incidence of hypertension, smoking or history of recent smoking,
      motion sickness or previous PONV. A bilateral DIEPflap is noted as bilat versus unilat and
      depending on the use of opioids postoperative an Apfel score is calculated. The number of
      anti emetic drugs given before any PONV took place and the number given after PONV is
      calculated, the incidence of nausea and the incidence of vomiting is measured. The maximum
      visual analog score (VAS) during the first 24 hours and the total equivalent dose of morphine
      used in the first 24 hours is measured.

      Postoperative flap skin temperature was measured every hour in the first 24 hours and
      compared to a reference skin temperature close by.

      Perioperative complications during the first post-operative month were graded according to a
      score (CLAVIEN), (DINDOO).

      DIEPflap failure was defined as the need for a revision procedure that fails in preserving
      the flap and requires a new or other flap procedure.

      The investigators calculated length of hospital stay (LOS) as the total number of nights in
      hospital after surgery.

      The investigators retrieved all measured factors potentially related to complications of
      grade I to grade V or healthcare utilization outcomes from the database and medical records.
      Post-operative opioids were defined as the total dose of opioids used during the first 24
      hours post-operatively, calculated as iv morphine equivalents. The following were considered
      equivalent to 1 mg iv morphine: 1 mg iv or subcutaneous piritramide, 10 mg iv tramadol, or 2
      mg sublingual oxycodone.
    

Intervention name(s): opioid free anesthesia
Intervention type(s): Other
Intervention description(s): general anesthesia blocking reflexes without using an opioid
Intervention MeSH terms: Analgesics, Opioid; Anesthetics
Observational model: Cohort
Time perspective: Prospective
Sampling method: Non-Probability Sample
Study population: 
        woman who are admitted for breast reconstruction using the diepflap (free flap)