Postoperative respiratory arrhythmias: incidence and measurement.
BACKGROUND
Postoperative respiratory disturbances may be the result either of depression of respiratory drive, or alteration of respiratory pattern.


METHODS
Using an inductance plethysmograph, we continuously recorded the breathing in 52 patients for 4 h after major thoracic, abdominal, and body surface surgery. The ventilatory response to hypercapnia was measured preoperatively, and at the start and end of the observation period.


RESULTS
From a variety of statistical measures of respiratory depression, it was found that the occurrence of apnoeas (breath times >10 s), did not correlate with measures of respiratory drive, or with dose or route of administration of opioid, site of surgery, pain, or drowsiness. Instead, the incidence of apnoeas correlated most closely with measures of respiratory pattern (standard deviation of breath times (r=0.72), the mean breath time (r=0.63), approximate entropy of the breath times (r= -0.32)). Twenty-nine percent of patients had some breath times (Ttot) longer than 20 s.


CONCLUSIONS
We would conclude that changes in respiratory pattern are not closely correlated with changes in traditional measures of respiratory drive.
Sleigh
J W
JW
Department of Anaesthesia, Waikato Hospital, Hamilton, New Zealand.
D000005:Abdomen / Q000601:surgery; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000701:Analgesics, Opioid / Q000008:administration & dosage / Q000627:therapeutic use; D000704:Analysis of Variance; D001049:Apnea / Q000175:diagnosis / Q000209:etiology; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D006935:Hypercapnia / Q000503:physiopathology; D015994:Incidence; D001239:Inhalation / Q000502:physiology; D008297:Male; D008875:Middle Aged; D010149:Postoperative Pain / Q000503:physiopathology; D010991:Plethysmography; D011183:Postoperative Complications; D012123:Pulmonary Ventilation / Q000502:physiology; D012119:Respiration / Q000187:drug effects; D012120:Respiration Disorders / Q000175:diagnosis / Q000209:etiology*; D012143:Respiratory Physiological Phenomena / Q000187:drug effects; D012894:Sleep Stages / Q000502:physiology; D019616:Thoracic Surgical Procedures; D013990:Tidal Volume; D013997:Time Factors
D000701:Analgesics, Opioid