|LETTER TO EDITOR
|Year : 2016 | Volume
| Issue : 11 | Page : 864-866
The significance (or the insignificance) of wide pulse pressure
Ying Hui Low, Charles S Brudney, Srinivas Pyati
Department of Anesthesiology, Duke University Medical Center and Durham VA Medical Center, Durham NC 27710, USA
|Date of Web Publication||9-Nov-2016|
Department of Anesthesiology, Duke University Medical Center and Durham VA Medical Center, Durham NC 27710
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Low YH, Brudney CS, Pyati S. The significance (or the insignificance) of wide pulse pressure. Indian J Anaesth 2016;60:864-6
We would like to describe a case where we observed an extremely low diastolic pressure and an exaggerated pulse pressure of unclear aetiology. This case concerns an 85-year-old male with a forearm squamous cell lesion who presented for resection. Preoperatively, he did not report any symptoms of valvular heart disease, although mild aortic incompetence was reported in previous echocardiography. His medical history was significant for moderate chronic obstructive pulmonary disease, coronary artery disease, well-controlled hypertension and normal heart rate. Pre-operative laboratory results were normal. Pertinent medications included aspirin 163 mg daily, amlodipine 10 mg daily, metoprolol 50 mg twice a day, terazosin 10 mg and carbamazepine 200 mg thrice a day for orofacial pain.
On the day of surgery, his first recorded blood pressure (BP) was 128/33 mm Hg (mean arterial pressure [MAP] 60 mm Hg) on arrival to the operation theatre (OT) (preoperative BP was 107/66 mm Hg). His diastolic BP (DBP) did not increase and pulse pressure did not change after a 250 ml bolus of crystalloid. At this time, he had a normal, alert mental status and no neurological deficits were appreciated. After an otherwise uneventful, induction of anaesthesia with propofol, fentanyl and rocuronium, he was maintained on sevoflurane anaesthesia. An arterial line was placed for invasive BP monitoring. During the entire duration (about 6 h), his non-invasive BP (NIBP) monitor and arterial line measurements correlated. His BP ranged between systolic BP (SBP) of 81-118 mm Hg and DBP of 28-39 mm Hg (MAP 32-55 mm Hg), and his heart rate was between 50 and 85 beats/min in sinus rhythm. There were no difficulties in oxygenation or ventilation.
At the end of the case, the trachea was extubated and patient transported to the Intensive Care Unit (ICU) for postoperative monitoring.
On arrival to the ICU, he once again demonstrated an exaggerated low DBP and widened pulse pressure [Figure 1], at one point having a recorded BP of 92/14 mm Hg (MAP 13 mm Hg) and 87/45 mm Hg (mean 59 mm Hg). HR was 89 beats/min with sinus rhythm and oral temperature was 36.8°C. For the next 6 h, the range of his BPs was between 104-134 mmHg systolic and 16-29 mm Hg diastolic (MAPs 42-60 mm Hg), heart rate 79-94 beats/min and oxygen saturation 97%-99%. A transthoracic echocardiogram was carried out to investigate whether he had undiagnosed worsening of his aortic regurgitation; however this only revealed mild aortic insufficiency, with an estimated left ventricular ejection fraction >55% and no other significant cardiac pathology. He was administered a 250 ml bolus of crystalloids on arrival without a change of diastolic pressure, after which he was placed on maintenance crystalloid fluid only. By post-operative day 1, his BP normalised to 107/80 mm Hg without any further intervention.
|Figure 1: (Philips IntelliVue MP90): A sample of the patient's vital signs on arrival in the Intensive Care Unit post-operatively showing persistently widened pulse pressure and very low diastolic blood pressure|
Click here to view
In adults, a wide pulse pressure may be the result of cardiovascular pathology, for example, severe aortic regurgitation or severe atherosclerotic disease. , These, however, would be expected to lead to chronic recordings of a wide pulse pressure, not just during the perioperative period. A search of the existing literature revealed that widened pulse pressure is mainly associated with atherosclerotic disease and stiffening of arterioles, resulting in an amplification of the pressure transmitted along peripheral vessels  and may not accurately reflect central pressures. An increased pulse pressure is also associated with an increased risk of heart failure,  increased risk of stroke after cardiac surgery,  and an increased risk of fatal and non-fatal adverse cerebral and cardiac outcomes in patients undergoing cardiac surgery. 
We propose that, based on physiologic mechanisms, the potential causes of a wide pulse pressure in surgical patients include: (1) Severe intravascular hypovolaemia or vasoplegia that should respond to volume repletion or discontinuation of anaesthetic agents. (2) A hyperdynamic circulation during sepsis, anaphylaxis or liver failure, when there are severe vasodilation and increased cardiac output, can also lead to a widened pulse pressure. Sepsis would be accompanied by other signs of an inflammatory syndrome and a possibly known infectious source. Anaphylaxis would often be associated with clinical signs and can be confirmed by raised tryptase levels. (3) Hypothermia-causing severe systemic vasoconstriction could temporarily exacerbate a pre-existing mild or moderate aortic regurgitation. (4) In an underdamped arterial BP monitoring system, systolic measurements will be higher and diastolic measurements lower than actual pressures, but the MAP will stay relatively unaffected. This will lead to a discrepancy with SBP and DBP on arterial line although similar MAP on invasive and NIBP measurements will be seen.
In the present case, the aetiology of an extremely low diastolic pressure and wide pulse pressure remains unclear. The patient had mild aortic insufficiency on transthoracic echocardiogram, was normothermic, had no other evidence of, or causes to suspect ongoing sepsis or liver failure, and the DBP was not fluid-responsive. The significance of unexplained wide pulse pressure in our patient only resulted in increased attention by providers towards the arterial trace without any adverse consequence in the patient. The aforementioned case adds to the literature pool of unexplained physiological disturbances that occur routinely in the perioperative period that may sometimes require 'inactivity and watchful expectancy'.
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