K . Komeswaran et al .: J Extra Corpor Technol 2024 , 56 , 114 – 119 115 effectiveness , such as inhaled volatile anesthetics ( IVA ) and / or Extracorporeal Membrane Oxygenation ( ECMO ) [ 8 ].
Recent literature from the Extracorporeal Life Support Organization ( ELSO ) registry has reported among the small population that receive ECMO for SA , survival rates are as high as 94 % [ 8 , 9 ]. There is even less reported data describing the benefit and appropriate timing when using IVA as a rescue therapy for SA [ 10 – 12 ]. While ECMO and IVA are both considered “ rescue therapy ”, it is unclear from existing literature if the use of IVA prevents the further need for ECMO support and if there is a comparative difference in mortality between the two therapies .
In our study , we look at a series of patients with status asthmaticus who received either IVA , ECMO , or both as rescue therapy after failing conventional bronchodilator therapies . Our aim was to compare clinical parameters of individual patients who received IVA and subsequently ECMO as rescue therapies and to describe the morbidities and mortality rates among patients who received these therapies in our institution . Our study will add to the small existing literature on use of unconventional rescue therapies for SA and specifically report outcomes on patients who received IVA prior to ECMO .
Materials and methods Study design
This is a retrospective descriptive study of children between 2 and 18 years of age , seen at an urban academic tertiary care Children ’ s Hospital PICU . Using a combination of the Virtual Pediatric Systems ( VPS ) database and our institution ’ s Extracorporeal Life Support Organization ( ELSO ) data , patients who were admitted to the PICU between January 2014 and July 2020 with an ICD 10 code of SA who received IVA and or ECMO were identified . A retrospective chart review was done which identified a total of 1772 children with status asthmaticus admitted during this time period . Patients with status asthmaticus who received IVA and or ECMO were included in our study . A total of seven patients who received these rescue therapies were identified . These patients were then categorized into three cohorts : 1 ) patients who received IVA alone , 2 ) patients who first received IVA and then subsequently received ECMO , and 3 ) patients who received ECMO alone . The need for informed consent was waived , and institutional review board approval was obtained . ECMO circuits used in our unit had a Rotaflow pump and were primed with blood . Anesthesia ventilators to administer volatile anesthetics were co-managed with the help of anesthesiologists . Sevoflurane and Isoflurane were utilized at a starting dose of 0.5 % and titrated to achieve the desired therapeutic effect . Patient data collected included demographic characteristics , therapeutic interventions before rescue therapy , ventilatory parameters , ICU and hospital length of stay , days on ECMO , ventilator days , number of days on sedation , and oxygen support complications , and mortality . The initial and subsequent blood gas parameters and ventilatory data chosen were PEEP , mean airway pressure ( MAP ), peak inspiratory pressure ( PIP ), pH , PaO 2 , andPaCO 2 . The initial lab and ventilatory data were the closest reported documentation before IVA or ECMO was initiated . The subsequent labs and ventilatory data were within 4 h after the initiation of rescue therapy .
Statistics
The identified cohort was small and is presented as a comparison among invasive rescue therapies , but the small sample size precluded meaningful statistical comparisons between all groups . When appropriate , data were described using median values with 25th and 75th interquartile or as percentages .
Results
A total of 1772 children with status asthmaticus were admitted to our PICU during the time frame of our study . Seven children with SA were included , who received only IVA ( n = 1 ), IVA and then ECMO ( n = 5 ) or ECMO alone ( n = 1 ). Demographic and clinical features are compared between the three groups in Table 1 . All children were in the young childhood range ( 2 – 8 years ). Five of the 6 patients were males . All children received standard asthma therapies of steroids , albuterol , magnesium sulphate and aminophylline prior to escalation with similar dosing ranges for all therapies . There were no established criteria which determined how patients who did not respond to conventional therapies were escalated . The patient on IVA alone received it for 166 h and the mean hours on IVA was much less ( 50 h ) for those who went on to receive ECMO with all 5 patients coming off IVA once cannulated . The mean hours on ECMO were 168 among those who received IVA prior and much longer ( 456 h ) than the patient who received ECMO alone . This specific patient was complex with a history of prematurity and developed acute respiratory distress syndrome after initial presentation for SA .
Table 2 describes each of the five patients who received inhaled anesthesia and then subsequently ECMO . Four of the five ECMO patients were cannulated percutaneously onto venovenous ( VV ) ECMO , which is our institution ’ s practice for ECMO cannulation when possible . One patient went on VV initially and one was converted to venoarterial ( VA ) secondary due to cardiac tamponade on ECMO . This was the only patient who died secondary to neurological injury during this event and withdrawal of ECMO support due to poor neurological prognosis . The patient who was placed on VA initially despite IVA had worsening pCO 2 to almost 250 mm Hg , and ECHO revealed significant right-sided cardiac failure from pulmonary hypertension caused by hyperinflation and therefore VA was chosen . Timing of ECMO initiation , length of IVA use , and hours of mechanical ventilation were all variable among each patient . One patient on ECMO was found to have developed an occipital subdural hematoma , noted two days after decannulation which did not require any neurosurgical intervention with spontaneous resolution on repeat imaging . One patient on VA ECMO had a large acute non-hemorrhagic infarct of left middle and posterior cerebral arteries found on post ECMO imaging as well , which did lead to right-sided hemiplegia .