Case report

Perioperative hypertension due to undiagnosedaortic coarctation: are current standards of careadequate?

MICHAEL ROSE B SB S cc ( M( M e de d ) M B B S) M B B S* AND DAVID

MURRELL B MB M e d S c ie d S c i M B B S F R C A F A N Z C AM B B S F R C A F A N Z C A†

*Provisional Fellow in Anaesthesia Royal North Shore Hospital Sydney and †Senior StaffSpecialist, Department of Anaesthesia The Children’s Hospital at Westmead Sydney, NSW,Australia

SummaryA 12-year-old male presented for a superficial parotidectomy for

chronic parotitis. The patient had an unremarkable past medical

history and was admitted on the day of surgery for his procedure

without further anaesthetic or surgical review. During the patient’s

intraoperative course, higher than expected blood pressures were

noted and treated with clonidine. After further high blood pressure

readings in the postoperative care unit, close surveillance of blood

pressures for the following 24 h was arranged. The hypertension was

ongoing, and further examination and investigation confirmed the

diagnosis of coarctation of the aorta. We examine the possible reasons

for failure to diagnose this patient’s hypertension preoperatively and

suggest that there is a need for greater surveillance of blood pressures

in the paediatric population presenting for surgery. A discussion of

the significance of hypertension in paediatrics and recommendations

for minimum standards of care to address shortcomings in the

diagnosis and treatment of paediatric hypertension are proposed.

Keywords: paediatric hypertension; aortic coarctation; secondary

hypertension; blood pressure

Introduction

Hypertension is a heterogenous disease affecting

both adult and paediatric populations. Whilst detec-

tion of hypertension in adults is commonplace and

usually aimed at identifying essential hypertension,

blood pressure in the paediatric population is less

commonly measured and, if elevated, harder to

interpret and easily dismissed. It is more likely in

this population to be of secondary cause and the

manifestation of another potentially serious disease

entity. As anaesthetists, we have an important role in

paediatric blood pressure measurement and an even

greater responsibility to investigate abnormal read-

ings. We report a case of previously undiagnosed

coarctation of the aorta causing perioperative hyper-

tension and suggest that there is a need for greater

surveillance of blood pressure in the paediatric

population presenting for surgery.

Correspondence to: Michael Rose, Department of Anaesthesia andPain Management, Royal North Shore Hospital, Pacific Highway,St Leonards, NSW 2065, Australia (email: drmichaelrose@yahoo.com.au).

Pediatric Anesthesia 2004 14: 357–360

� 2004 Blackwell Publishing Ltd 357

Case report

A 40 kg, 12-year-old male presented for a right

superficial parotidectomy for swelling secondary to

chronic parotitis from duct obstruction. The request

for admission was from the surgeon’s private con-

sulting rooms and a preoperative health question-

naire completed by the parents revealed the patient

to be in good health, except for a recent ear infection

treated with antibiotics. Past medical history was

remarkable only for inguinal hernia repair at age 5

and adenotonsillectomy at age 6. There had been no

problems with general anaesthesia. The patient was

scheduled to be admitted on the day of surgery,

without further surgical or anaesthetic review.

Preoperatively, nursing staff recorded weight,

temperature and pulse, all within normal limits. A

blood pressure reading was not taken at this time.

The patient was then reviewed by the anaesthetist,

who assessed the medical history and discussed

likely anaesthetic and postoperative issues. No

formal clinical examination was undertaken. As the

patient was very anxious, oral premedication of

0.35 mgÆkg)1 midazolam was given 30 min prior to

induction of anaesthesia.

Anaesthesia was induced in the anaesthetic room

using a mixture of oxygen, nitrous oxide and

sevoflurane. Monitoring included pulse oximetry,

capnography and agent monitoring, but not blood

pressure. After gaining intravenous access, a dose of

0.1 mgÆkg)1 of vecuronium and 0.125 mgÆkg)1 mor-

phine were administered and the patient was intu-

bated uneventfully. The patient was then transferred

to the operating table and full monitoring including

ECG, noninvasive blood pressure (Datex Ohmeda

AS-3, right arm), pulse oximetry, capnography and

agent monitoring was established. Maintenance of

anaesthesia was facilitated by an oxygen/nitrous

oxide (0.5 : l) and isoflurane (endtidal concentration

approximately 1.2%) mixture. A second dose of

0.05 mgÆkg)1 morphine was administered 90 min

postinduction.

The initial blood pressure was 115/55 mmHg,

recorded approximately 15 min postinduction. Dur-

ing the first 3.5 h of the procedure, heart rate and

carbon dioxide were normal. The majority of blood

pressures recorded were above a systolic of 130 and

diastolic of 70 mmHg, ranging between 115/55 and

155/90 mmHg, recorded 3.5 h after induction. At

this time, with approximately 1.2 MAC of isoflura-

ne/nitrous oxide and minimal surgical stimulation,

clonidine was administered (60 lg IVI over 60 min).

This resulted in a lowering of blood pressure during

the remainder of the case. The final blood pressure

measured in the operating room was 115/55 mmHg.

The patient entered the postoperative care unit

approximately 5 h after induction of anaesthesia.

Initial blood pressure (measured by cuff on right

arm) was 159/63, followed 15 mins later by 193/72.

The patient was given a further dose of clonidine,

with good effect and a 24 h blood pressure chart

with 2 h measurement was commenced. The surgi-

cal team was advised of the anaesthetist’s concerns

regarding the elevated blood pressure and requested

to arrange referral and investigation if the patient’s

hypertension continued.

During the next 24-h period, blood pressure was

persistently mildly elevated (130–150/50–70 mmHg).

On one occasion, a single dose of 30 lg clonidine

was administered for a blood pressure of 155/

80 mmHg. Cardiology and renal consultsations were

subsequently organized and further history of a

‘benign heart murmur’ (diagnosed at age 3 by a

paediatrician but not investigated) was forthcoming.

Physical examination at this time found a grade 1–2/

6 mid-systolic murmur loudest at the left sternal

edge, radiating to the back. Femoral pulses were

present but difficult to palpate, and radiofemoral

delay was noted. Echocardiography was performed,

and a diagnosis of coarctation of the aorta was

confirmed. The patient was discharged home on the

second postoperative day with outpatient cardiology

follow-up, and for cardiac surgical review.

Discussion

This case of undiagnosed aortic coarctation causing

perioperative hypertension demonstrates many sys-

temic factors that lead to confusion about the

significance of intraoperative hypertension in a

surgical patient admitted without prior anaesthetic

review.

At no stage prior to induction of anaesthesia was

a full physical examination performed, which

may have revealed a cardiac murmur. As the

patient was referred for surgery directly from the

surgeon’s consulting rooms and assessed as being a

low-risk surgical candidate, a preanaesthetic clinic

358 M. ROSE AND D. MURRELL

� 2004 Blackwell Publishing Ltd, Pediatric Anesthesia, 14, 357–360

appointment and formal admission by a resident

medical officer were not undertaken. Preoperative

examination of the praecordium and lungs by the

anaesthetist is the usual practice at our institution

but did not occur in this case, largely as a result of

the patient’s late arrival to hospital and the time

necessary to address some complex issues relating

to his anxiety.

Similarly, no blood pressure recording was taken

preinduction. The current policy in the surgical

admission unit is to obtain a preoperative blood

pressure only on patients with a history of cardiac or

renal disease, or those presenting for tonsillectomy.

It is common practice at our institution, as with

many others, to only obtain blood pressure record-

ings in children postinduction, especially in the

absence of clinical concern.

These systemic factors combined to cloud the

significance of blood pressure recordings seen intra-

operatively and in the early postoperative period.

For this reason the patient’s blood pressure was

recorded over an extended period until such time as

enough measurements were available to establish a

trend. Alternatively, had elevated blood pressure

been noted immediately preoperatively, it might

have been attributed to excessive anxiety displayed

at this time. It is therefore suggested that blood

pressure measurement should be regarded as a

routine observation in all children, recorded at the

time of initial consultation wherever possible.

Significance of perioperative hypertensionin paediatrics

Hypertension has been estimated to be present in

approximately 1% of children and adolescents (1).

Assessing the significance of hypertension in paedi-

atrics, however, is confounded by potential inaccur-

acy in measurement, reporting and interpretation of

readings due to the lack of standards for defining

hypertension in children.

Errors in the measurement of blood pressure may

stem from inappropriate cuff size or position,

human or machine error, and movement of an

uncooperative patient, all of which may lead to

spurious blood pressure readings.

Surveys have revealed that there is little stan-

dardization in recording of blood pressure results. A

recent survey of British paediatricians revealed that

diastolic pressure was recorded at Korotkoff phase

IV by 51.4% of respondents, phase V by 31.9%, with

15.9% measuring both points (2). This is despite the

recommendation of a working group (The National

High Blood Pressure Education Program in the

United States) in 1996 (1) firmly recommending that

phase V should be used for diastolic measurement.

This exacerbates the difficulty in assessing the

significance of measured blood pressures.

There is further difficulty assessing the signifi-

cance of blood pressure measurements as a result of

variability within and between individuals (3), and

variability in published reference ranges that may or

may not be adjusted for age, weight, sex or pubertal

development. Hypertension has been defined arbi-

trarily using centile data alone (1) or centile data and

pathological features. Using this method it is poss-

ible to grade paediatric hypertension as being

borderline if systolic and/or diastolic pressures are

repeatedly greater than 90th centile and occasionally

greater than the 95th centile. Mild/moderate hyper-

tension is defined as greater than 95th centile and

without end organ involvement or severe if repeat-

edly above the 95th centile plus 15 mmHg or

elevation of blood pressure with target organ

involvement (4). Definitions of disease based upon

statistical estimates of normality are flawed as they

are statistical estimates without biological meaning

(3) and the same proportion of the population

remain hypertensive despite trends in that popula-

tion toward lower or higher pressures (i.e. if 95% is

taken, 5% will always be hypertensive) (4). Patho-

logical definitions, such as those including endorgan

involvement suffer from being late measures of

disease, and diagnosis is often delayed and may

require invasive tissue sampling.

High blood pressure recordings discovered peri-

operatively are not an uncommon phenomenon in

both adult and paediatric populations. Causes com-

mon to both include spurious hypertension (as a

result of equipment error, misplacement or incor-

rectly sized cuffs), pain, anxiety and the administra-

tion of pressor pharmacological agents. In the adult

population, essential or primary hypertension is

extremely common, hypertension persisting after

treatment of reversible triggers in the paediatric

population is less so, however, it is more likely to be

secondary (or nonessential) in nature (approximately

0.1% of the paediatric population) (3). As a result,

HYPERTENSION DUE TO UNDIAGNOSED AORTIC COARCTATION 359

� 2004 Blackwell Publishing Ltd, Pediatric Anesthesia, 14, 357–360

investigation of this group for the cause is more likely

than in adults to result in the diagnosis of a specific

renal (60–70%), renovascular (10%) (3), cardiac,

endocrine or metabolic disorder that may be amen-

able to specific treatment, especially in the presence of

both systolic and diastolic hypertension (5).

This case of coarctation of the aorta remaining

undiagnosed until age 12 is surprisingly not unusual.

Our institution sees approximately 10–15 newly

diagnosed cases of coarctation per year in children

beyond the first year of life (personal communica-

tion: G. Sholler, cardiologist, Children’s Hospital at

Westmead, Sydney Australia). Ing et al. (6) reported

50 consecutive patients older than 1 year, having

surgical correction of coarctation of the aorta and

noted a mean and median age of referral to a

cardiologist of 8.4 and 5.8 years, respectively. Of this

group, 26% were referred for cardiological review at

greater than 10 years of age. The authors also cited

abundant evidence that delayed diagnosis is associ-

ated with increased incidences of residual hyperten-

sion, morbidity and mortality. This evidence

underlines the importance of blood pressure screen-

ing in children and adolescents and the appropriate

investigation of abnormal results.

Without focusing too closely on exact definitions

of hypertension, an index of suspicion should be

maintained when anaesthetizing children. When

unexpectedly high blood pressure recordings are

found, they should not instantly be dismissed as

related to anxiety or pain, but further recordings

over time should be taken. If these pressures do not

alleviate suspicion, then investigation for a secon-

dary cause should proceed, with nonurgent surgery

deferred if necessary. Particular note should be

taken of children and adolescents with both diastolic

and systolic readings well above the 95th centile, as

these patients frequently have a specific underlying

cause of their hypertension (1).

This case provides an interesting insight into

systemic issues within a tertiary referral teaching

hospital that led to a child with aortic coarctation

being anaesthetized and undergoing surgery before

diagnosis or investigation of hypertension. It also

provides an illustration of how unexplained periop-

erative hypertension in the paediatric population

should be addressed and investigated due to the

high rate of potentially significant and often treata-

ble disorders associated with it.

We question whether current haphazard approa-

ches to measuring and interpreting blood pressure

in children are resulting in failure to detect serious

pathology and associated morbidity and mortality.

Following this concern, we would recommend the

following as a minimum standard of care:

1 Routine measurement on at least one occasion

between booking and admission prior to surgery

in all children between 3 years of age and adol-

escence (ages recommended in the 1977 (7) and

1987 (8) reports of the US Task Force).

2 Provision of dedicated admission procedures,

sufficient time and adequate facilities to allow

thorough clinical examination.

3 Careful postoperative scrutiny of children with

borderline blood pressure readings, using 24 h of

recorded measurements. Referral for investigation

if doubt persists.

4 Immediate referral and investigation of children

with pressures well above 95th centile readings.

5 Encouragement of debate in the international

anaesthetic literature of recommended strategies

for the detection of secondary hypertension in

children.

References1 National High Blood pressure Education Program Working

Group on Hypertension Control in Children and Adolescents.Update on the 1987 Task Force Report on high blood pressurein children and adolescents: a working group report from thenational high blood pressure education program. Pediatrics1996; 98: 649–658.

2 Lip GYH, Beevers M, Beevers DG et al. The measurement ofblood pressure and the detection of hypertension in childrenand adolescents. J Hum Hypertens 2001; 15: 419–423.

3 Goonasekera CDA, Dillon MJ. Measurement and interpretationof blood pressure. Arch Dis Child 2000; 82: 261–265.

4 Dillon MJ. Modern management of hypertension. In: MeadowR, ed. Recent Advances in Paediatrics, Vol 7. Edinburgh: ChurchillLivingstone, 1984: 35–53.

5 Sorof JM. Systolic hypertension in children: benign or beware?Pediatr Nephr 2001; 16: 517–525.

6 Ing FF, Starc TJ, Griffiths SP et al. Early diagnosis of coarctationof the aorta in children: a continuing dilemma. Pediatrics 1996;98: 378–382.

7 National Heart, Lung, and Blood Institute. Report of the taskforce on blood pressure control in children. Pediatrics 1977; 59:

797–820.8 National Heart, Lung, and Blood Institute. Report of the second

task force on blood pressure control in children – 1987. Pediat-rics 1987; 79: 1–25.

Accepted 19 August 2003

360 M. ROSE AND D. MURRELL

� 2004 Blackwell Publishing Ltd, Pediatric Anesthesia, 14, 357–360