Outcomes in General Anaesthesia versus Sedation
Levels of sedation can vary with the drugs being used, the response of
those drugs by the patients, their co-morbidities, and lifestyle/social
history such as alcohol use. Sedation can range from minimal to
conscious to deep should be performed by a clinician experienced in the
use and monitoring of patients under anaesthesia.
Table 2 shows the American Society of Anaesthesiologists Definition of
General Anaesthesia and Levels of Sedation/Analgesia
Renner et al studied the outcomes of patients at a single centre
undergoing TAVI with either GA or Conscious sedation (CS) with
anaesthesia performed by two experienced cardiac anaesthesiologists.
Both groups used low dose midazolam IV (intravenous) at 0.01-0.02 mg/kg
prior to the procedure. Both groups had an arterial line and central
venous catheter. Patients in the GA groups had either an endotracheal
intubation or a laryngeal mask airway (LMA). Those who had an
endotracheal intubation were able to have transoesophageal
echocardiography (TOE), whereas those with a LMA and in the CS group had
transthoracic echocardiography (TTE) before and after the procedure.
Total intravenous anaesthesia (TIVA) was used in the GA group with
either a bolus of propofol or etomidate on induction followed by
continuous infusion of propofol (3-5 mg/kg/hr) and remifentanyl (0.3-0.4
mcg/kg/min) and rocuronium as a muscle relaxant. The CS group used much
lower doses of propofol (0.3-0.5 mg/kg) and remifentanyl (0.02-0.06
mcg/kg/min) and 5-10 ml of 1% Mepivicaine was infiltrated to the groin
at the site of vascular access. 107 patients were in the GA group with a
mean age of 82 (6.1) years, and 93 patients in the CS group with a mean
age of 82 (6.4). There was no difference between groups in terms of
co-morbidities, New York Heart Association (NYHA) classification or
LogEuroSCORE. Conversion from CS to GA was needed in 5 cases: 4 due to
procedural complications and 1 due to agitation. Mean anaesthesia time
was significantly longer in the GA group, as expected more anaesthetic
agents such as propofol was used up in the GA group and so the need to
reach haemodynamic stability with the use of vasopressors and IV fluids
were more common in the GA group. Lower mean arterial pressure (MAP) was
noted in the GA group. Shorter intensive care unit (ICU) stays were
noted in the CS group, though there was no difference in length of stay
in hospital between the groups. There was no significant different in
30-day mortality between the groups. Even in those who were high risk
with a LogEuroSCORE >22 there was no difference in
intra-procedural characteristics between groups. 9.3% patients all of
whom were in the GA group required cardiopulmonary resuscitation.
[6]
Husser et al studied the outcomes of patients receiving TAVI with the
support of either GA or LA or CS (LACS). 16543 patients from multiple
centres across Germany were enrolled, mean age was 81 years and LACS was
used as the primary approach in 49% of cases. LACS was more likely to
be conducted in experienced TAVI centres. Procedural success was
achieved in 97.5%. The LACS group showed shorter procedural duration
and fluoroscopy time. Conversion to sternotomy and bleeding
complications were less frequent in the LACS group, though vascular
complications were higher. Rate of device embolization and malposition
was less in the LACS group. There was no difference in paravalvular leak
(PVL) between groups. Post procedural course was less complicated in the
LACS group such as delirium, respiratory failure, CPR. Duration of ICU
and hospital stay was shorter in the LACS group in population matched
analysis. 30-day mortality was less in the LACS group, though there was
no significant difference at 1 year mortality. [7] Miles et al in a
single centre study looked at the outcomes of GA and CS in patients
enrolled for TAVI. CS involved a remifentanyl infusion at 0.05
mcg/kg/min with a fascia iliaca block ilioinguinal block using 2 mg/kg
0.25% levobupivacaine. 118 patients were involved with 44 receiving CS.
There was a 17% reduction in anaesthetic time and a 29% reduction in
recovery room time in the CS group. Reduction in inotrope requirement
was seen in the CS group and no difference were seen in terms of
postprocedural complications between groups. 7% from the CS group
required ICU admission with one due to respiratory failure needing
tracheal intubation. 14% in the GA group need ICU admission. 4 patients
required conversion to GA. [8] Goren et al in a single centre study
involving 204 patients undergoing TAVI found significantly less use of
catecholamines and intravenous fluids in patients received sedation over
GA. Total procedural times were also less. Conversion to GA occurred in
4.6%. In hospital mortality and total length of stay were similar
between groups. [9]
Thiele et al performed a multi-centre randomised trial (SOLVE trial) of
patient undergoing TAVI with either GA or CS with LA. Patient included
had severe AS, age >75 years and high risk for surgical
valve replacement. GA was provided via TIVA with continuous infusion of
propofol and remifentanyl maintaining a BIS of 40-60. LA was provided by
the interventionalist. CS was given either by dexmedetomidine, propofol
or other nonbenzodiazepine drugs and titrated to keep BIS
>70. Ventilation was monitored with capnography and
supplemental oxygen was given. 225 patients were randomly assigned to
the GA group and 222 to CS. Mean age was 81.6+/-5.5 years, a median
logEuroSCORE of 14.8% and similar baseline characteristics between
groups. Conversion to GA from CS occurred in 5.9% with the reasons
being the need for CPR, respiratory insufficiency, and agitation.
Minimum oxygen saturation during anaesthesia and cerebral oxygen
saturation at the end of the procedure was significantly lower in the CS
group. As expected, the quantity of anaesthetic agents used were greater
in the GA group. At 30 days the rate of the composite primary end point
of all cause mortality, stroke, myocardial infraction, acute kidney
injury was similar between groups. Device time, procedural time, POD,
moderate to severe prosthetic valve regurgitation at 30 days and
cardiovascular mortality did not differ significantly between groups.
Mean length of ICU and hospital stays were similar. The need for
vasopressor and inotropes were greater in the GA group. [10]