The Science Journal of the American Association for Respiratory Care

2007 OPEN FORUM Abstracts

DETECTION OF RESPIRATORY DEPRESSION PRIOR TO EVIDENCE OF HYPOXEMIA IN PROCEDURAL SEDATION

J. Bazin1


Introduction:
Capnography monitors ventilation, oximetry measures arterial oxygenation and perfusion(SpO2). Here we report recognition of respiratory depression by capnography prior to SpO2 alert. The result of the capnography alone drove the clinical intervention.

Case Summary:
A 62-yr old female underwent endoscopic retrograde cholangiopancreatography (ERCP). Patient was monitored by ECG, NIBP, SpO2, RR and EtCO2. Exhaled CO2 was sampled using the Smart BiteBloc™ (Oridion sampling line and bite block system) while also providing O2 at 3 lpm. Capnography waveform and measured RR and EtCO2 values were posted on the Oridion Microcap Plus monitor. Sedation induced with IV alfentanil 500 mcg and propofol 150 mg. Propofol IV at 500 mg/hr maintained sedation.
At 8 minutes post-induction SpO2 95%, capnograph indicated apnea. Intervention of jaw subluxation and reduction of propofol to 400 mg/hr to correct. At minute 20 (five minutes post IV bolus of alfentanil 500mcg) hypoventilation was indicted (RR of 6 and etCO2 of 44mm Hg) with SpO2 at 96%. In response, propofol drip was stopped and O2 increased to 5L/min. At 25 minutes, propofol was resumed at 300 mg/hr.

Discussion: During the ERCP, capnography continuously monitored patient ventilation and indicated respiratory depression before other monitoring parameters indicated physiological compromise. The capnography data was used to drive clinical interventions and improved patient safety with a positive outcome. This case report on sedation with supplemental oxygen delivery underlines the superior sensitivity of capnography, compared with other monitoring modalities, to recognize early respiratory depression. Early recognition of compromised ventilation creates an opportunity for earlier clinical intervention in order to prevent hypoventilation induced hypoxemia.

Monitored Parameters During Sedation for ERCP
 Baseline Start Min. 5 Min. 8* Min. 9 Min.15 Min.17 Min.20* Min.25* Min.30
NIBP mmHg 134/85 143/85 110/83 127/85 138/92 154/95 128/77 112/75 115/82 126/77
HR/min 72 78 67 73 83 82 66 68 72 75
Sp02% 98 98 96 97 97 98 97 96 95 98
RR/ min 18 22 18 None 15 20 12 6 10 15
etCO2mmHg 32 30 36 0 38 28 39 44 45 38

*Data which drove a clinical intervention such as jaw subluxation , adjustment of propofol drip rate, and adjustment of O2 delivery rate


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