The frequency and timing of respiratory depression in 1524 postoperative patients treated with systemic or neuraxial morphine.
OBJECTIVE
To describe the frequency and timing of intravenous patient-controlled analgesia (IV-PCA) or neuraxial morphine-induced postoperative respiratory depression.


METHODS
Audit of data captured by routine quality assurance of the acute pain protocols that were implemented by nurses performing routine postoperative care.


METHODS
The surgical wards of a university-affiliated, 700-bed, tertiary hospital.


METHODS
In real time, the data of all patients enrolled into our Acute Pain Service (APS) were entered and stored in the APS database. Thereafter, patients who had received IV morphine via a PCA device or neuraxial morphine between January 1999 and December 2002 were isolated. From this subset, all patients in whom a respiratory rate (RR) less than 10 breaths per minute was recorded were retrieved.


RESULTS
From a total of 4500 patients, IV or neuraxial morphine was administered to 1524 patients. Eighteen (1.2%) cases of an RR less than 10 breaths per minute were recorded (13 patients, 4 patients, and 1 patient in the IV-PCA, daily epidural morphine, and single-dose intrathecal morphine groups, respectively). A direct correlation between intraoperative fentanyl administration and postoperative respiratory depression was demonstrated between the IV-PCA (P = 0.03) and epidural groups (P = 0.05). The time from IV-PCA initiation or last neuraxial morphine administration until the diagnosis of respiratory depression ranged between 2 hours and 31.26 hours and 2 hours and 12.15 hours, respectively. Ten (55.6%) patients received naloxone.


CONCLUSIONS
Morphine-induced respiratory depression may occur at any time during the APS admission. However, the optimal frequency of intermittent RR monitoring is unknown. Furthermore, because multiple variables (age, sex, prior opioid administration, site of operation) may affect morphine-induced respiratory depression, further investigation must be performed to determine the ideal monitoring protocol.
Shapiro
Arie
A
Department of Anesthesiology, Critical Care and Pain Management, Meir Hospital, Kfar Saba 44281, Israel.
Zohar
Edna
E
Zaslansky
Ruth
R
Hoppenstein
David
D
Shabat
Shay
S
Fredman
Brian
B
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D015360:Analgesia, Epidural; D016058:Analgesia, Patient-Controlled; D000701:Analgesics, Opioid / Q000008:administration & dosage* / Q000009:adverse effects* / Q000627:therapeutic use; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000627:therapeutic use; D002648:Child; D003864:Depression, Chemical; D004008:Diclofenac / Q000627:therapeutic use; D005260:Female; D006635:Histamine H2 Antagonists / Q000627:therapeutic use; D006801:Humans; D007262:Infusions, Intravenous; D007278:Injections, Spinal; D008297:Male; D008875:Middle Aged; D009020:Morphine / Q000008:administration & dosage* / Q000009:adverse effects* / Q000627:therapeutic use; D010147:Pain Measurement; D010149:Postoperative Pain / Q000188:drug therapy; D011899:Ranitidine / Q000627:therapeutic use; D015656:Respiratory Mechanics / Q000187:drug effects*; D012189:Retrospective Studies
D000701:Analgesics, Opioid; D000894:Anti-Inflammatory Agents, Non-Steroidal; D006635:Histamine H2 Antagonists; D004008:Diclofenac; D009020:Morphine; D011899:Ranitidine