Postoperative Myocardial Ischaemia: Temporal Association With Nocturnal Hypoxaemia

Abstract

Three patients presenting for elective aortic surgery were studied before operation and for up to 3 days after operation with ambulatory electrocardiographic monitoring and nocturnal pulse oximetry. Supplementary oxygen was administered for the first 2 days after operation and withdrawn on the 3rd morning after operation. Heart rate remained increased for the first 3 days after operation. Two patients developed episodes of myocardial ischaemia during the first 48 h after operation while their arterial oxygen saturation remained greater than 90%. On the third day, and during the third night after operation, both the severity and duration of myocardial ischaemia increased markedly, associated with arterial hypoxaemia. A temporal relationship between decreases in oxygen saturation and fluctuations in ST segment level were observed in the three patients.

Obstructive Sleep Apnea Syndrome and Perioperative Complications: A Systematic Review of the Literature

“…REM sleep is also associated with increased sympathetic discharge leading to tachycardia, hemodynamic instability, and myocardial ischemia. [60][61][62][63][64] It is well known that most complications after the surgery occur in the first postoperative week, especially between postoperative days 2 and 5, corresponding to periods of REM rebound. Episodes of hypoxemia after surgery have been reported to occur mostly between postoperative nights 2 to 5.…”

Perioperative Management of Obstructive Sleep Apnea With Nasal Continuous Positive Airway Pressure

“…It has been suggested that OSAS may be a major cause of these unexpected cases of postoperative cardiac ischemia or death. 11,12 NCPAP is an effective treatment for obstructive sleep apnea. Despite the patient's diagnosis of severe obstructive sleep apnea, she did not experience airway obstruction or desaturation in the postoperative period when nasal CPAP was maintained up to the time of discharge.We suggest that a regimen of NCPAP initiated prior to surgery and resumed immediately after extubation may allow patients to be treated safely with conventional anesthetic and analgesic agents, and that OSAS patients who receive NCPAP may follow perioperative courses comparable to those of patients without OSAS.…”

The effects of hypoxaemia and recommendations for postoperative oxygen therapy

“…However, in a further study, in postoperative patients [ 181, myocardial ischaemia was related to episodic hypoxaemia in some patients and in others hypoxaemia was associated with tachycardia and arrhythmias (median Spo, 78%, range 60-89%). Oxygen administration will correct myocardial ischaemia in certain patients [8] [20]. In a model of myocardial ischaemia in the dog using critical constriction of a coronary artery, hypoxaemia (F102 0.1) caused an increase in heart rate, a decrease in stroke volume and depression of regional myocardial function [2 I].…”

“…The pulse oximeter finger probe is accurate to I % in the normal range but with a sudden hypoxic episode an Spo, reading of 55% may be 7% lower than the actual Sao, [7]. Using pulse oximetry there are reports of postoperative hypoxaemia with arterial oxygen saturations of less than 75% for periods of longer than 2 h [2,8,9]. The cause has now been shown to be a combination of: (a) Impaired control of both ventilation and upper airway patency due to the combined effects of opioids and sleep [2, lo].…”

“…However, in a further study, in postoperative patients [ 181, myocardial ischaemia was related to episodic hypoxaemia in some patients and in others hypoxaemia was associated with tachycardia and arrhythmias (median Spo, 78%, range 60-89%). Oxygen administration will correct myocardial ischaemia in certain patients [8], but some patients develop silent myocardial ischaemia when normoxic. While myocardial ischaemia and hypoxaemia may occur independently of each other, Gill et al suggest that ischaemia will occur if hypoxaemia is severe ( < 85%) and prolonged (> 5 min) [19].…”