CLINICAL REPORT
Monitored anesthesia care with dexmedetomidine
of a patient with severe pulmonary arterial hypertension
for inguinal hernioplasty
Hiromi Shinohara • Kiichi Hirota • Masami Sato •
Masahiro Kakuyama • Kazuhiro Fukuda
Received: 4 March 2010 / Accepted: 15 April 2010
 Japanese Society of Anesthesiologists 2010
Abstract The presence of severe pulmonary arterial
hypertension (PAH) is a significant risk factor of major
perioperative cardiovascular complications in patients
undergoing even non-cardiac surgery under anesthetic
management. The most important aspect of perioperative
care of PAH patients is to avoid pulmonary hypertensive
crisis, which can be induced by alveolar hypoxia, hypox-
emia, hypercarbia, metabolic acidosis, airway manipula-
tions, and activation of the sympathetic nervous system by
noxious stimuli. We report a case of successful monitored
anesthesia care supplemented by dexmedetomidine for
inguinal hernioplasty of a patient with severe PAH sec-
ondary to congenital heart disease.
Keywords Pulmonary arterial hypertension 
Monitored anesthesia care  Dexmedetomidine
Introduction
Perioperative patient management, including anesthetic
care, for patients with severe pulmonary arterial hyper-
tension (PAH) is among the most challenging of critical
care [1–3]. The anesthetic management of patients with
PAH leads to a number of difficult problems, especially
when regional anesthesia with central neuraxial blockade
techniques is considered to be contraindicated. We report
successful ilioinguinal/iliohypogastric block-assisted mon-
itored anesthesia care (MAC) supplemented by dexmede-
tomidine for inguinal hernioplasty of a patient with severe
PAH secondary to congenital heart disease.
Case report
A 21-year-old male (weight 38 kg; height 150 cm) was
scheduled to undergo hernioplasty for right inguinal hernia
with recurrent local swelling and pain. At the age of
1 month, he was diagnosed with atrial septal defect (ASD),
ventricular septal defect (VSD), and persistent left superior
vena cava. VSD closed spontaneously at the age of 1 year
and 4 months. He was diagnosed with pulmonary hyper-
tension at the age of 5 years. The latest heart catheteriza-
tion (2 months before the hernioplasty) revealed severe
PAH at rest under administration of 9 ng/kg/min prosta-
glandin I2 (PGI2) by way of superior vena cava and 250 mg
bosentan per day (Table 1). Cardiac function assessed by
cardioechography showed ASD and slight tricuspid
regurgitation. SpO2 was 90% under 2 L/min oxygen ther-
apy at rest. Dyspnea was functional class IV [4]. Six-
minute walk distance was about 500 m under oxygen
therapy. He was prescribed 2 L/min oxygen therapy at
night. His current medication consisted of spironolactone,
furosemide, allopurinol, and bosentan per os and continu-
ous infusion of PGI2 [5, 6]. He was medicated with neither
anticoagulant nor antiplatelet drug.
At the preoperative consultation, the patient was con-
sidered as ASA III [7]. Because of the high risk of general
anesthesia and regional anesthesia with central neuraxial
blocks from the points of view of circulation stability and
anticoagulated state due to PGI2 administration, MAC with
ultrasound-guided ilioinguinal/iliohypogastric block was
H. Shinohara  K. Hirota (&)  M. Sato  M. Kakuyama 
K. Fukuda
Department of Anesthesia, Kyoto University Hospital,
54 Shogoin-Kawaracho, Sakyo-Ku, Kyoto 606-8507, Japan
e-mail: hif1@mac.com
K. Hirota
Day Surgery Unit, Kyoto University Hospital, Kyoto, Japan
123
J Anesth
DOI 10.1007/s00540-010-0959-5

discussed and approved by the patient. The patient also
approved off-label use of dexmedetomidine for anesthesia.
On the day of surgery, he was admitted to our day surgery
unit on foot with continuous administration of 9 ng/kg/min
PGI2 and premedication with spironolactone, furosemide,
allopurinol, and bosentan. In the operation room, the
patient was positioned supine. SpO2 was 90%. PaO2 and
PaCO2 were 62 and 26.6 mmHg, respectively, with 3 L/
min oxygen therapy through facemask in supine position.
Expiratory air was sampled from nostrils to measure EtCO2
and respiratory rate. An ultrasound-guided ilioinguinal/
iliohypogastric block was performed after intravenous
injection of 2 mg midazolam. 20 mL 0.5% ropivacaine
was administered under real-time ultrasound imaging to
detect both the position of the needle tip and the spread of
the local anesthetic. Airway devices, including oral and
nasal airways, laryngeal mask airway, or cuffed oropha-
ryngeal airway, were not used. MAC was then induced
with intravenous administration of 0.4 lg/kg/h dexmede-
tomidine. After 15 min, the systemic blood pressure was
100/55 mmHg and the BIS number dropped from 95 to
around 60. HR and respiratory rate were stable around
60 bpm and 18 times/min, respectively. Dose of dex-
medetomidine was titrated between 0.2 and 0.3 lg/kg/h to
give a BIS value around 65, or between levels 3 and 4 of
the Ramsay sedation score (RSS) [8]. Blood gas analysis
after completion of sedation revealed PaO2 = 60 Hg and
PaCO2 = 30.0 mmHg. The hernioplasty with mesh plug
was performed supplemented with intermittent local infil-
tration of 0.5% ropivacaine (total 32 mL) by surgeons.
During the 71 min-operation, 4 mg ephedrine was injected
once to treat systemic hypotension (75/40 mmHg). After
the episode, the BP remained in the 85–95 mmHg systolic
range for the remainder of the anesthesia. Oxygen satura-
tion was around 90% throughout the anesthesia. Estimated
blood loss was little and a total of 400 mL of crystalloid
fluid was infused during 125 min anesthesia. After the
operation, administration of dexmedetomidine was dis-
continued and the patient was transferred to the post
anesthesia care unit (PACU). After 20 min, he emerged
from MAC (RSS: level 2). He did not complain of dyspnea
or wound pain at more than 20 mm of visual analogue
scale (VAS) during the PACU. He did not request any pain
killers in the ward. The patient was discharged on post
operation day 1 with continuous infusion of PGI2 without
any circulatory crisis.
Discussion
A primary objective of anesthetic management in patients
with PAH is to minimize increases in pulmonary vascular
resistance and to maintain systemic vascular resistance [1,
3]. Abrupt increases in pulmonary vascular resistance may
induce acute right ventricular failure or oxygen desatura-
tion followed by reduced cardiac output in patients with
intracardiac shunting. Pulmonary vascular resistance rap-
idly increases in response to a variety of stimuli, including
alveolar hypoxia, hypoxemia, hypercarbia, metabolic aci-
dosis, and activation of the sympathetic nervous system by
noxious stimuli [1, 2, 7]. Hypoxemia and alveolar hypoxia
are independent and additive pulmonary vasoconstrictors.
General anesthesia also may cause significant hemody-
namic instability in response to laryngoscopy, intubation,
surgical incision, and the anesthetics themselves. Tracheal
intubation has been reported to induce pulmonary hyper-
tensive crisis and death in patients with severe PAH,
especially at the time of induction of anesthesia. Positive-
pressure ventilation may inhibit systemic venous return and
can increase right ventricular afterload by closing of small
pulmonary arteries [1, 3, 9].
Regional anesthesia also may be an acceptable alterna-
tive to general anesthesia for patients undergoing periph-
eral procedures such as inguinal hernioplasty. However,
central neuraxial blocks may produce unacceptable
decreases in systemic vascular resistance in patients with
unrestrictive intracardiac shunts, and this action could
exacerbate right to left shunting. In addition, those are
contraindicated for the anticoagulated patients. Because of
administration of PGI2, which has a potent antiplatelet
effect, anesthesia adopting central neuraxial blocks was
avoided in this case.
Peripheral nerve blocks improve post-discharge anal-
gesia and reduce opioid-related side effects, thereby facil-
itating the fast-track recovery process. The combination of
local anesthesia and/or peripheral nerve blocks with intra-
venous sedative and analgesic drugs is commonly referred
to as MAC and has become popular in the ambulatory
setting [10]. Compared with general endotracheal and
central neuraxial anesthetic techniques, MAC-based tech-
niques can facilitate recovery in the ambulatory setting for
superficial surgical procedures. The local and peripheral
nerve blockage anesthetic technique that provides adequate
analgesia is also recommended to minimize the risk of side
effects and complications.
Table 1 Heart catheterization data
RAa LAa RVa mPAa aAoa CI
(L/min/m2)
Qp/Qs Rp/Rs
8/6 (5) 10/7 (5) 94/7 95/43 (63) 84/56 (67) 1.88 1.53 0.62
Heart catheterization result (2 months before the hernioplasty) is demonstrated
RA right atrium, LA left atrium, RV right ventricular, mPA main pulmonary
artery, aAo ascending aorta, CI cardiac index, Qp pulmonary blood flow, Qs
systemic blood flow, Rp pulmonary vascular resistance, Rs systemic vascular
resistance
a Values are in sys/dia (mean) mmHg
J Anesth
123